Abu Dhabi, United Arab Emirates. STANDARD CONSTRUCTION SPECIFICATIONS (PART 2 - ROAD STRUCTURES, 2020)

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Table 21-3: Normal-weight concrete slump test limits at the time of placement

Type of Work

Nominal Slump (mm) Maximum Slump (mm)

Formed Elements:

Sections more than 300 mm thick

Sections 300 mm thick or less

– 75

– 100

125*

Cast-in-place piles and drilled shafts not vibrated

125

– 200

225

Concrete placed under water

125

– 200

225

Filling for riprap

– 175

200

•

*When GGBS is used the maximum slump may increase to 180.

When Type F or G high-range, water-reducing admixtures are used, the Contractor may exceed the
slump limits in

Table 21-3, as permitted by the Engineer.

When the consistency of the concrete is found to exceed the nominal slump, the Contractor shall
adjust the mixture of subsequent batches to reduce the slump to a value within the nominal range.
Batches of concrete with a slump exceeding the maximum specified shall not be used in the work.

If concrete of adequate workability cannot be obtained by the use of the minimum cement content
and WC ratio allowed, adjustment shall be made with an approved admixture, and the WC ratio shall
be maintained as low as possible as per approved concrete mix design.

21.4.3

Cement Control for Concrete Mixing

Cement content minimums shall conform to the requirements of Table 4-16 of Chapter 4, Concrete
Works, of these Standard Specifications

;

or as otherwise specified in the Contract documents. Actual

cement content used shall sufficiently produce concrete of the required strength, consistency, and
performance.

21.4.4

Concrete Admixtures

Concrete admixtures shall comply with ASTM C494 / C494M

– 12 or BS EN 480-2:1997, and shall

be added to the concrete mix at the time of batching the concrete and in accordance with the
Manufacturer

’s written procedure, and as approved by the Engineer. Copies of the Manufacturer’s

written procedure shall be furnished to the Engineer prior to use of any admixture. Any deviations
from these written procedures shall be submitted to the Engineer for approval. Admixtures shall not
be added to the concrete with the modified procedure until the Engineer has approved them in
writing.

When the Contractor proposes to use admixtures from different admixture manufacturers, the
Contractor shall provide evidence from the Manufacturers to the Engineer that the admixture will be
compatible and does not adversely affect the air-void system, strength, durability, and performance
of the hardened concrete. Test results complying with ASTM C457 / C457M - 11 shall serve as
evidence to satisfy this requirement.

Concrete admixtures shall not be used at site.

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21.4.5

Mineral Admixtures

Mineral admixtures shall be used in the amounts specified in the Contract documents. When mineral
admixtures are neither specified in the Contract documents nor prohibited, they shall be comparable
to the specified type of cement, and the Contractor shall comply with the requirements of Section
4.3.6 of Chapter 4, Concrete Works, of these Standard Specifications

21.4.6

Chemical Admixtures

Chemical admixtures shall be used as specified in the Contract documents. Otherwise, such
admixtures may be used, at the option and expense of the Contractor, and when permitted by the
Engineer, to increase the workability or alter the time-of-set of the concrete. Using calcium chloride
shall not be permitted. Chemical admixtures for concrete shall be tested in accordance with ASTM
C494 / C494M

– 12.

Methods and equipment for measuring and adding additives shall be approved by the Engineer.
Equipment at the batching plant that does not accurately dispense the correct amount of additive in
an acceptable manner shall not be approved.

21.4.7

Corrosion Inhibitor for Structural Concrete Works

Liquid concrete admixture shall be provided by the Contractor as required by the Contract documents
to protect the steel reinforcement from corrosion induced by carbonation, chloride and atmospheric
attack as specified herein and directed by the Engineer. The Contractor shall add to all Cast-In-Place
(CIP) structural concrete works a corrosion inhibitor as recommended by the Manufacturer, as
specified in Table 4.7 of Chapter 4, Concrete Works, of these Standard Specifications, and as
approved by the Engineer. The corrosion Inhibitor shall possess the following properties:

1. Proven effective when tested in accordance to ASTM G109 - 07 for a testing period not less

than 10 years

2. Complies to requirements of ASTM C494 / C494M

– 12

3.  Complies to the requirements of ASTM C1582 / C1582M - 11
4.  Proven effective in modified cracked beam testing
5.  Established international and regional track-record in excess of 20 years
6.  Protects both anodic and cathodic components of the corrosion cell
7.  Homogeneous; settlement should not be observed with time
8.  The  Manufacturer  shall  be  ISO  9001  and  ISO  14001  certified  for  the  design  and

manufacturing of corrosion protection systems and concrete protection products with a valid
(up-to-date) certificate.

9. Approved and certified by BBA, MPA Stuttgart or equivalent.

21.5

Manufacture of Concrete

Ready-mixed concrete production and concrete produced by stationary plant shall conform to the
requirements of AASHTO M157 and the requirements of Section 4.3 of Chapter 4, Concrete Works,
of these Standard Specifications.

21.5.1

Delivery of Concrete

To ensure continuous delivery, at the rate required for the Project, the company supplying concrete
shall have sufficient plant capacity and transporting apparatuses. Concrete delivery rates during
concreting operations shall be such as to provide for the proper handling, placing, and finishing of
the concrete. These rates shall ensure that the interval between batches does not exceed 20 minutes
and shall sufficiently prevent joints within a monolithic pour caused by placing fresh concrete against
concrete in which the initial set has already occurred. Delivery and handling methods shall facilitate
concrete placing with minimal re-handling and without damaging the structure or the concrete.

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21.5.2

Concrete Sampling and Testing

In addition to the requirements and standard methods provided in Section 4.3 of Chapter 4, Concrete
Works, of these Standard Specifications

compliance with the requirements indicated in this section

shall be determined in accordance with the following standard methods of the AASHTO, ASTM, or
BS EN:

•

Sampling Fresh Concrete, AASHTO R 60-12 (ASTM C172 / C172M - 10)

•

Weight per Cubic Metre, Yield, and Air Content (Gravimetric) of Concrete, AASHTO T

121M/T 121-12 (ASTM C138 / C138M - 12)

•

Sieve Analysis of Fine and Coarse Aggregate, AASHTO T27-11 (ASTM C136 - 06)

•

Slump of Portland Cement Concrete, AASHTO T 119M/T 119-11 (ASTM C143 / C143M -

10a)

•

Testing Fresh Concrete, Slump-Test, BS EN 12350-2:2009

•

Air Content of Freshly Mixed Concrete by the Pressure Method, AASHTO T 152-12 (ASTM

C231 / C231M - 10)

•

Specific Gravity and Absorption of Fine Aggregate, AASHTO T 84-10 (ASTM C128 - 12)

•

Specific Gravity and Absorption of Coarse Aggregate, AASHTO T 85-10 (ASTM C127 - 12)

•

Determining Density of Structural Lightweight (Low-Density) Concrete, ASTM C567 / C567M

- 11

•

Making and Curing Concrete Test Specimens in the Laboratory, AASHTO T 126 (ASTM

C192 / C192M - 07)

•

Making and Curing Concrete Test Specimens in the Field, AASHTO T 23-08 (ASTM C31 /

C31M - 12)

•

Testing Hardened Concrete, Compressive Strength of Test Specimens, BS EN 12390-

3:2009

21.5.2.1

Concrete Sampling

One set consisting of nine (9) cubes (15cm) shall be made in accordance with BS EN 12390-1:2000
and BS EN 12390-2:2009 from a sample taken from each randomly selected batch of concrete.
Samples shall be taken at the point of discharge from the delivery truck. Unless otherwise instructed
by the Engineer the rate of sampling of randomly selected batches from same plant shall be as given
in Table 21-4, but not less than one sample shall be taken on each day that concrete of that class is
used.

The nine cubes shall be numbered consecutively and marked with the date, the section of work from
which it was taken and any other information required and dispatched to the approved laboratory for
testing for compressive strength.

Table 21-4: Rates of sampling and testing from same plant

Number of trucks

Rate

(1) Truck

(1) set

(2-4) Trucks

(2) sets

(5-10) Trucks

(3) sets

(11-40) Trucks

(4) sets

> 40

One set for each 100 m

21.5.2.2

Frequency of Testing for Concrete Aggregates

Unless otherwise instructed by the Engineer, the aggregates in use shall be regularly tested in a
laboratory acceptable to the Engineer at a frequency not less than that indicated in Table 21-5:

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Table 21-5: Frequency of aggregate testing

Test

Frequency

Remarks

Particle size distribution by sieve analysis

Weekly

More frequently at start of production

Clay, fine silt, et.

Weekly

Sand equivalent of fine aggregate

Bi-weekly

Fineness modulus of fine aggregate

Bi-weekly

Clay lumps

Bi-weekly

Flakiness index

Bi-weekly

Reducing to weekly when stable.

Elongation index

Bi-weekly

Reducing to weekly when stable.

Specific Gravity of coarse and fine
aggregates

Weekly

Reducing to bi-weekly when stable.

Water absorption

Weekly

Reducing to bi-weekly when stable.

Bulk density and voids of aggregate

Weekly

Organic impurities

Weekly

Aggregate crushing value

Weekly

10% fines

Weekly

Aggregate Impact Value

Weekly

Los Angeles abrasion resistance

Bi-weekly

Sulfate content

Bi-weekly

Chloride content

Bi-weekly

Voided Shell Content

Bi-weekly

Reducing to monthly when stable

Cement

– Aggregate Reactivity

Initially for each source and as directed by the
Engineer

Sulfate soundness

Monthly

Drying Shrinkage

Initially for each source and as directed by the
Engineer

Others

As required by the Engineer

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21.5.3

Evaluation of Concrete Strength

21.5.3.1

Concrete Strength Tests

Cubes Nos. 1, 5 and 9 shall be tested after 7 days. If the average of the three 7-day test cubes is
below the minimum requirement, the Contractor must immediately stop all concreting until checks
are made on the material and equipment and immediately rectify any defect which has become
apparent as the result of such checking. If the Contractor elects to remove and replace the defective
concrete without waiting for the results of the 28-day test, concreting can then continue entirely at
the responsibility of the Contractor. Cubes Nos. 2 and 8, 3 and 7, and 4 and 6 will be considered
three individual samples or sets and after 28 days of curing shall be tested as specified above. If
either of the cubes in any set shows definite evidence, other than low strength, of improper sampling,
molding, handling, curing or testing, said cube shall be discarded and the strength test shall consist
of the strength of the remaining cubes.

21.5.3.2

Requirements for Controlling Construction Operations

For determining adequacy of cure and protection, and for determining when loads or stresses can
be applied to concrete structures, test cubes shall be cured at the structure site under conditions that
are not more favourable than the most unfavourable conditions for the portions of the structure that
they represent, as described in AASHTO T 23-08 (ASTM C31 / C31M - 12), Article 9.4. Sufficient
test cubes, as specified in Article 21.5.2.1, shall be made and tested at the appropriate ages to
determine when operations, such as release of falsework, application of prestressing forces, or
placing the structure in service, can occur.

21.5.3.3

Requirements for the Acceptance of Concrete

All concrete shall be accepted based on adherence to the requirements of this chapter and Section
4.3.12 of Chapter 4, Concrete Works, of these standard specifications.

When determining compliance of concrete with a specified strength, test cubes shall be cured under
controlled conditions, as described in Article 9.3 of AASHTO T 23-08 (ASTM C31 / C31M - 12); and
shall be tested at the specified age.

Final acceptance of the concrete works is based on 28 days' testing on the three sets of two cubes
each.  The  work  is  considered  in  compliance  if  the  average  of  the  three  sets  of  cubes  equals  or
exceeds the minimum specified for the class of concrete being placed, and if the average of the two
cubes in any one set does not fall below the specified minimum strength by more than 3.4 MPa. If
the  results  of  the  28-day  testing  are  unsatisfactory,  the  Contractor,  in  accordance  with  the
instructions of the Engineer, shall conduct tests in the suspect parts of the structure. The concrete
may be test loaded in-situ or cylindrical test cores may be drilled out and tested in accordance with
BS  EN  12390-3:2009.  Should  the  tests  prove  that  the  concrete  is  unsatisfactory  or  below  the
standards specified, the Engineer may order the concrete to be removed and replaced with concrete
of the specified quality. All the above shall be at the expense and responsibility of the Contractor.

21.5.3.4

Requirements for the Control of Mix Design

Whenever the average of three consecutive strength tests that were made to determine acceptability
of the concrete falls to less than 1.03 MPa below the specified strength, or any single strength test
falls more than 1.38 MPa below the specified strength, the Contractor shall, at the Contractor's
expense, make corrective changes in the materials, mix proportions, or concrete manufacturing
procedures before placing additional concrete from that class. Such changes shall be approved by
the Engineer prior to use.

a. Precast Concrete Cured by Waterproof Cover Method, Steam, or Radiant Heat

When a precast concrete member is cured by the waterproof cover method, steam, or radiant heat,
the compressive strength test cubes made for any of the above purposes shall be cured under
conditions similar to the member. Such concrete shall be considered acceptable whenever a test

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indicates that the concrete has reached the specified compressive strength if such strength is
reached no later than the specified age for the compressive strength.

Test cubes shall be cured by only one of the following methods:

•

For concrete with specified design compressive strengths less than or equal to 41.4 MPa,

test cubes shall be stored next to the member and under the same covers so that the cubes
are exposed to the same temperature conditions as the member.

•

For all specified concrete strengths, test cubes shall be match-cured in chambers in which

the temperature  of  the  chamber  is  correlated  with  the  temperature  in  the  member  prior  to
release  of  the  prestressing  strands.  Temperatures  of  the  chamber  and  member  shall  be
verified  by  use  of  temperature  sensors  in  the  chamber  and  member.  Unless  specified
otherwise,  temperature sensors  in I-beams shall  be  located  at the  centre  of gravity  of the
bottom flange. For other members, the temperature sensors shall be located at the centre of
the thickest section. Locations shall be specified in the Contract documents. After release of
the  prestressing  strands,  cubes  shall  be  stored  in  a  similar  temperature  and  humidity
environment as the member.

21.6

Protection of Concrete during Placing and Curing

Precautions  shall  be  taken  as  needed  to  protect  concrete  from  damage  due  to  weather  or  other
environmental  conditions  during  placing  and  curing  periods.  Concrete  damaged  by  weather
conditions shall be either repaired to an acceptable condition or removed and replaced.

21.6.1

Rain Protection

Under conditions of rain, the placing of concrete shall not commence, or shall stop, unless adequate
protection is provided to prevent damage to the surface mortar or damaging flow or wash of the
concrete surface.

21.6.2

Hot-weather Protection

The recommendations of the American Concrete Institute Standard "Guide to Hot Weather
Concreting", ACI 305R-10

, and “Cooling and Insulating Systems for Mass Concrete”, ACI 207.4R-

05, shall be followed. Proposals for hot weather concreting shall be included with the submissions
for trial mixes.

Concrete mixture temperatures immediately before placement shall be between 10 degrees Celsius
and 32 degrees Celsius, except as otherwise provided herein.

When the ambient temperature is above 32 degrees Celsius, the forms, reinforcing steel, steel-beam
flanges, and other surfaces that will come in contact with the mix shall be cooled to below 32 degrees
Celsius by means of a water spray

— or other approved methods.

Concrete temperatures at time of placement shall be maintained within the specified temperature
range by any combination of the following:

•

Shading the materials storage areas or the production equipment;

•

Cooling the aggregates by sprinkling with water that conforms to the requirements of Article

4.4.1.3 of Chapter 4, Concrete Works, of these Standard Specifications;

•

Shading the steel reinforcement;

•

White painting the transit mixer and covering it with hasin;

•

Reducing the time between placing of concrete and start of curing to minimum possible;

•

Using chilled water of a temperature below 4

˚ C;

•

Cooling the aggregates or water by refrigeration or replacing a portion of the mix water with

ice that is flaked or crushed to the extent that the ice will completely melt while mixing of the
concrete; and,

•

Injecting liquid nitrogen.

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21.6.3

Special Requirements for Bridge Decks

When placing concrete in bridge decks or other exposed slabs, the Contractor shall ensure that the
evaporation rate does not exceed the bleeding rate. In no case the evaporation rate shall be more
than 0.5 kg per square metre per hour. The evaporation rate maybe estimated from ACI 308R-01
chart shown in Figure 21-1.

When necessary, the Contractor shall take one or more of the following actions to reduce the
evaporation rate:

•

Construct windbreaks or enclosures to effectively reduce the wind velocity throughout the

area of placement;

•

Use fog sprayers upwind of the placement operation to effectively increase the relative

humidity; and,

•

Reduce the temperature of the concrete according to Section 21.6.3.

Figure 21-1: Evaporation rate nomograph from ACI 308

During periods of low humidity, wind, or high temperatures, and prior to the application of curing
materials, the Contractor shall protect concrete being placed and finished for bridge decks from
damage due to rapid evaporation. Such protection shall prevent premature crusting of the surface
or an increase in drying cracking. Such protection shall be provided by raising the humidity of the
surrounding air with fog sprayers operated upwind of the deck, by employing wind-breaks or sun-

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shades, additionally reducing the temperature of the concrete, scheduling placement during the
cooler times of days or nights, or any combination thereof.

For bridge decks that are located over or adjacent to salt water or when specified in the Contract
documents, the maximum temperature of the concrete at the time of placement shall be 27 degrees
Celsius.

21.6.4

Concrete Exposed to Salt Water

Unless  otherwise  specified  in  the  Contract  documents,  concrete  for  structures  exposed  to  salt  or
brackish water shall comply with the requirements of Class C40/20 concrete. Such concrete shall be
mixed for a period of not less than two minutes and the water content of the mixture shall be carefully
controlled  and  regulated  so  as  to  produce  concrete  of  maximum  impermeability.  To  produce
maximum  density  and  a  complete  lack  of  rock  pockets,  the  concrete  shall  be  thoroughly
consolidated,  as  necessary.  Unless  otherwise  indicated  in  the  Contract  documents,  the  clear
distance from the face of the concrete to the reinforcing steel shall be not  less than 100 mm. No
construction joints shall be formed between levels of extreme low and high water, or the upper limit
of  wave  action,  as  determined  by  the  Engineer.  Between  these  levels,  the  forms  shall  not  be
removed,  or  other  means  provided,  to  prevent  salt  water  from  coming  in  direct  contact  with  the
concrete  for  a  period  of  not  less  than  30  days  after  placement.  Except  for  the  repair  of  any  rock
pockets and the plugging of form-tie holes, the original surface

— as the concrete comes from the

forms

— shall be left undisturbed. Special handling shall be provided for precast members to avoid

even slight deformation cracks.

21.6.5

Concrete Exposed to Sulphate Soils or Sulphate Water

When the Contract documents identify the area as containing sulphate soils or sulphate water, the
concrete that will come in contact with such soil or water shall be Class C40/20 and shall be mixed,
placed, and protected from contact with soil or water, as required for concrete exposed to salt water;
however, the protection period shall be not less than 72 hours.

21.7

Handling and Placing Concrete

Concrete shall be handled, placed, and consolidated by methods that shall not cause segregation of
the mix and will result in a dense homogeneous concrete that is free of voids and rock pockets. The
Contractor-selected methods shall not cause the displacement of reinforcing steel, or other
materials, to become embedded in the concrete. Concrete shall be placed and consolidated prior to
initial set and in no case more than 1.5 hours after the cement was added to the mix. This time limit
maybe increased to 2.0 hours when plasticizer type F, G, or D is used. Concrete shall not be re-
tempered.

Concrete shall not be placed until the Engineer has inspected and approved the forms, all materials
to be embedded, and the adequacy of the foundation material for spread footings. Prior to
commencing placement, the Contractor shall remove all mortar from pervious placements, debris,
and foreign material from the forms and steel. Immediately before placing the concrete against the
forms and subgrade, it shall be thoroughly moistened with water. Temporary form spreader devices
may be left in place until concrete placement precludes their need, after which they shall be removed.

Placement of concrete for each section of the structure shall be done continuously without
interruption between planned construction or expansion joints. Delivery rates, placing sequences,
and methods shall be such that fresh concrete is always placed and consolidated against previously
placed concrete before its initial set has occurred.

During and after the placement of concrete, care shall be taken not to injure the concrete or break
the bond with reinforcing steel. Workers shall not walk in fresh concrete. Platforms for workers and
equipment shall not be supported directly on any reinforcing steel. Once the concrete is set, forces
shall not be applied to the forms or to reinforcing bars that project from the concrete until the concrete
is of sufficient strength to resist damage.

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21.7.1

Placement Sequences

Whenever a concrete placement plan or schedule is specified or approved, the sequence of
placement shall conform to the approved plan. Unless otherwise specifically permitted by the
Contract documents, the requirements of the following specifications shall apply.

21.7.1.1

Vertical Members

Concrete for columns, substructure and culvert walls, and other similar vertical members shall be
placed and allowed to set and settle for a period of time before placing concrete for integral horizontal
members

— such as caps, slabs, or footings. Settling periods shall adequately allow the completion

of settlement due to loss of bleed water and shall be not less than 12 hours for vertical members
measuring more than 4.5 m in height and not less than 30 minutes for members measuring more
than 1.5 m, but not more than 4.5 m in height. When friction collars or falsework brackets are
mounted on vertical members, and unless otherwise approved, the vertical member shall have been
in place at least seven days and shall have attained its specified strength before loads from horizontal
members are applied.

21.7.1.2

Superstructures

Unless otherwise permitted, no concrete shall be placed in the superstructure until substructure
forms have been stripped sufficiently to determine the character of the supporting substructure
concrete.

T-beams and Deck Girder Spans

Concrete for T-beam or deck girder spans whose depth measures less than 1.2 m may be placed in
one continuous operation or may be placed in two separate operations; first, to the top of the girder
stems; and second, to completion. For T-beam or deck girder spans whose depth measures 1.2 m
or more, and unless the falsework is non-yielding, such concrete shall be placed in two operations,
and at least five days shall elapse after placement of stems before the top deck slab is placed.

Concrete Box Girders

Concrete for box girders may be placed in two or three separate operations consisting of bottom
slabs, girder stems, and top slabs. In either case, the bottom slab shall be placed first and, unless
otherwise permitted by the Engineer, the top slab shall not be placed until the girder stems have
been in place for at least five days.

Concrete sequence placement for the cast-in-place, multiple-cell box girders at bridges shall be as
follows:

The bottom slab, the exterior and interior web portions and the diaphragm portions shall be placed
monolithically, as indicated on the Contract drawings, and as specified herein.
Placement of the top slab shall occur. Top slabs shall not be placed until the girder webs have been
in place for at least five days.

Vertical  construction  joints  in  all  portions  of  the  multiple  cell  box  girders  shall  be  minimized  and,
where proposed, shall preferably be placed at 0.2 of the span length on either side of a supporting
pier.  Positive  moment  areas  shall  be  placed  first  followed  by  the  placement  of  concrete  for  the
negative  moment  area  over  the  pier.  Dependent  upon  the  volume  of  concrete,  additional  vertical
construction joints may be used

— subject to the Engineer’s approval.

A  concrete  pour  sequence  plan  shall  be  prepared  by  the  Contractor  for  each  superstructure  and
submitted to the Engineer for approval prior to commencing any bridge superstructure work.  Pour
sequence  plans  shall  show  the  locations  of  all  construction  joints  that  shall  be  bonded  joints,  as
specified herein. Concrete pours within each element shall be alternated to eliminate shrinkage to
the greatest extent possible.

Concrete placement in each pour shall start at the low point and shall continue upgrade, unless
otherwise permitted by the Engineer.

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Joints created due to the stopping of work shall be avoided as far as possible. Such joints shall be
constructed as directed by the Engineer, when necessary.

At deck median locations indicated on the Contract drawings, the Contractor shall apply a
commercial quality, bond-breaking compound to construction joint surfaces.

21.7.1.3

Arches

Arch ring concrete shall be placed in such a manner as to load the centring uniformly and
symmetrically. Arch rings shall be cast in transverse sections of such size that each section can be
cast in a continuous operation. Section arrangements and placement sequences shall be as
approved and shall avoid the creation of initial stress in the reinforcement. These sections shall be
bonded together by suitable keys or dowels. Arch barrels for culverts and, unless prohibited by the
Contract documents, other arches may be cast in a single, continuous operation.

21.7.1.4

Box Culverts

In general, the base slab or footings of box culverts shall be placed and allowed to set before the
remainder of the culvert is constructed. For culverts whose wall height measures 1.5 m or less, the
sidewalls and top slabs may be placed in one continuous operation. For higher culvert walls, the
requirements for vertical members shall apply.

21.7.1.5

Tunnels and Underpasses

Tunnel and underpass concrete shall be placed by pumping and shall be discharged into the work
through a pipe inserted into the formed space. Discharge lines shall be graduated to indicate the
depth of filling at any time. Special care shall be taken to force concrete into all irregularities in work
surfaces and to completely fill tunnel/underpass walls and crown. Only experienced operators shall
operate placing equipment. Pumped concrete shall be vibrated by the Contractor. Concrete shall not
be pumped through aluminium alloy pipe.

21.7.1.6

Tunnels and Underpasses on Rock Surfaces

Rock surfaces against or upon which concrete is to be placed shall be clean; free of oil and other
objectionable  coatings,  water,  mud,  debris,  dummy  rock,  and  loose  semidetached  or  unsound
fragments;  and  shall  be  sufficiently  rough  to  assure  satisfactory  bond  with  the  concrete.
Discontinuities shall be cleaned to hard rock on the sides, and to a depth that is approved by the
Engineer.  All  overbreak  beyond  the  excavation  limit  shown  in  the  Contract  documents  shall  be
backfilled with shotcrete or concrete at the Contractor's expense.

21.7.1.7

Precast Elements

The sequence of placement for concrete in precast elements shall be such that sound, well
consolidated concrete that is free of settlement or shrinkage cracks is produced throughout the
member. Placing and compacting prestressed concrete members shall conform to Section 21.7.2,
Section 21.7.3, and Section 21.14.3

21.7.2

Concrete Placing Methods

Concrete shall be placed in its final position, as nearly as possible, and the Contractor shall not use
vibrators for extensive shifting of the weight of fresh concrete.

Concrete shall be placed in horizontal layers of a thickness not exceeding the capacity of the vibrator
to consolidate the concrete and merge it with the previous lift. In no case shall the depth of a lift
exceed 600 mm. Concrete placement rates shall not exceed those rates assumed for the design of
the forms

— as corrected for the actual temperature of the concrete being placed.

When placing operations involve dropping the concrete more than 1.5 m, the concrete shall be
dropped through a tube fitted with a hopper head

— or through other approved devices — to prevent

segregation of the mix and spattering of mortar on steel and forms above the elevation of the lift

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being placed. This requirement shall not apply to cast-in-place piling when concrete placement is
completed before initial set occurs in the first placed concrete.

21.7.2.1

Concrete Placing Equipment

All equipment used to place concrete shall be of adequate capacity and designed and operated so
as to prevent segregation of the mix or loss of mortar. Such equipment shall not cause vibrations
that might damage freshly placed concrete. Aluminium parts of the equipment shall not come in
contact with the concrete. Between uses, the Contractor shall clean the mortar coating inside placing
equipment that has set or dried out before its use is resumed.

Chutes shall be lined with smooth watertight material and, when steep slopes are involved, shall be
equipped with baffles or reverses.

Operation of concrete pumps shall product a continuous stream of concrete without air pockets.
When pumping is completed, the concrete remaining in the pipeline, if it is to be used, shall be
ejected in such a manner that there will be no contamination of the concrete or separation of the
ingredients.

Conveyor belt systems shall be as approved by the Engineer, and shall not exceed a total length of
168 m, measured from end to end of the total assembly. Belt assemblies shall be arranged so that
each section discharges into a vertical hopper arrangement to the next section. To keep segregation
to a minimum, scrapers shall be situated over the hopper of each section so as to remove mortar
adhering to the belt and to deposit it into the hopper. Conveyor belt system discharge ends shall be
equipped with a hopper and a chute

— or suitable deflectors — which shall allow the concrete to

drop vertically into the deposit area.

21.7.3

Consolidation Methods

All concrete, except concrete placed underwater and concrete otherwise exempt, shall be
consolidated by mechanical vibration immediately after placement.

Except as noted herein, vibration shall be internal. External form vibrators may be used for thin
sections when the forms have been designed for external vibration.

Vibrators shall be of approved type, design, and of a size appropriate for the work. They shall be
capable of transmitting vibration to the concrete at frequencies of not less than 75 Hz.

A sufficient number of vibrators shall be provided by the Contractor to properly compact each batch
of concrete immediately after it is placed in the forms. Additionally, the Contractor shall have at least
one spare vibrator immediately available in case of breakdown.

To  thoroughly  work  the  concrete  around  the  reinforcement  and  embedded  fixtures  and  into  the
corners  and  angles  of the forms,  the  Contractor shall  manipulate the  vibrators.  Vibration  shall  be
applied at the point of deposit and in the area of freshly deposited concrete; and the Contractor shall
insert  vibrators  into  and  withdraw  them  from  the  concrete  slowly.  Finally,  vibration  shall  be  of
sufficient duration and intensity to thoroughly consolidate the concrete but shall not be continued so
as to cause segregation.

Shall localized areas of grout form, vibration shall be halted. Vibrators applications shall be uniformly
spaced and not farther apart than 1.5 times the radius over which the vibration is visibly effective.
Vibration shall not be applied directly to, or through the reinforcement to, sections or layers of
concrete that have hardened to the degree that the concrete ceases to be plastic under vibration.
Vibrators shall not be used to transport concrete in the forms.

Where immersion-type vibrators are used to consolidate concrete around epoxy-coated reinforcing
steel, the vibrators shall be equipped with rubber or another non-metallic coating.

Vibration shall be supplemented by such spading as is necessary to ensure smooth surfaces and
dense concrete along form surfaces and in corners and locations impossible to reach with the
vibrators.

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When approved by the Engineer, the Contractor may consolidate small noncritical elements by using
suitable rods and spades.

21.7.4

Underwater Placement

Generally, the Engineer shall not permit the placement of concrete in/or underwater. Where the
Engineer specifically approves the placement of concrete in/or underwater, the Contractor shall
submit

its proposed construction procedure for placing the concrete for the Engineer’s approval

before proceeding with the work.

Methods for placing concrete in/or underwater shall keep as much of the concrete out of direct
content with the water as possible to avoid any rapid movement or agitation of the exposed surface.

Underwater concrete placement shall be continuous from start to finish. Concrete surfaces shall be
kept as nearly horizontal as practicable. To ensure thorough bonding, each succeeding layer of seal
shall be placed before the preceding layer has taken initial set. For large pours, more than one tremie
or pump shall be used to ensure compliance with this requirement.

To prevent segregation, concrete placed underwater shall be carefully placed in a compact mass, in
its final position, by means of a tremie, concrete pump, or other approved method; and shall not be
disturbed after being deposited. Still water shall be maintained at the point of deposit and the forms
underwater shall be watertight. Cofferdams shall be vented during placement and while curing the
concrete to equalize the hydrostatic pressure and thus prevent water from flowing through the
concrete.

21.7.4.1

Underwater Concrete Placement Equipment

Tremies shall consist of a watertight tube with a diameter measuring not less than 250 mm and fitted
with a hopper at the top. Aluminium pipes shall not be used. Tremies shall be supported so as to
permit  free  movement  of  the  discharge  end  over  the  entire  top  surface  of  the  work  and  so  as  to
permit rapid lowering, when necessary, to retard or stop the flow of concrete. To prevent water from
entering the tube before it is filled with concrete, the Contractor shall seal the discharge ends closed
at  the  start  of  work.  After  placement  begins,  the  tremie  tube  shall  be  kept  full  of  concrete  to  the
bottom  of  the  hopper.  If  water  enters  the  tube  after  placement  has  begun,  the  tremie  shall  be
withdrawn, the discharge end resealed, and the placement restarted. When a batch is dumped into
the  hopper,  the  flow  of  concrete  shall  be  induced  by  slightly  raising  the  discharge  end,  always
keeping it in the deposited concrete. Flows shall be continuous until the work is completed. When
cofferdam struts prevent the tremie's lateral movement, the Contractor shall use one tremie in each
bay.

Concrete pumps used to place concrete underwater shall include a device at the end of the discharge
tube to seal out water while the tube is first being filled with concrete. Once the flow of concrete has
begun, the Contractor shall keep the end of the discharge tube full of concrete and below the surface
of the deposited concrete until placement is completed.

Detailed propo

sals for concreting shall be submitted by the Contractor for the Engineer’s approval.

Where concrete is to be placed in/or underwater, the actual mix proportions and selection of
aggregates shall ensure a resulting concrete with good flow and cohesion characteristics.

Underwater cement content shall be 25 percent greater than for a comparable mix for use in dry
conditions; and, the Engineer shall approve the minimum works cube strength for all concrete for the
comparable mixes used in dry conditions.

21.7.4.2

Underwater Concrete Placement Cleanup

Dewatering  may  proceed  after  test  specimens  cured  under  similar  conditions  indicate  that  the
concrete  has  sufficient  strength  to  resist  the  expected  loads.  All  laitance,  or  other  unsatisfactory
materials, shall be removed from the exposed surface by scraping, chipping, or other means  that
shall not injure the concrete surface before placing foundation concrete.

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21.7.5

Reinforced-concrete Bridge Slabs

This work shall form and construct reinforced-concrete bridge slabs in accordance with this chapter,
the requirements of this section, and the Contract documents.

Unless otherwise shown in the Contract drawings, all cast-in-place reinforced-concrete bridge slabs
shall be Class C40/20.

21.7.5.1

Construction of Reinforced-concrete Bridge Slabs

Cast-in-place Slabs

Conventional forms, permanent metal deck forms, or prestressed concrete panels shall be used by
the Contractor as indicated in the Contract plans and in accordance with Article 1.20.8.2 of Chapter
1, General Requirements, and as approved by the Engineer. Permanent metal deck or conventional
forms shall be used by the Contractor for thickened slabs, diaphragms, or other regions

— as shown

in the Contract plans where prestressed concrete panels are not used.

Slabs shall be constructed as shown in the Contract plans and in accordance with the following
pertinent requirements:

•

Chapter 4, Concrete Works, of these Standard Specifications;

•

Chapter 5, Reinforcing Steel, of these Standard Specifications;

•

Chapter 21, Concrete Structures, of these Standard Specifications; and,

•

Chapter 22, Prestressing Systems, of these Standard Specifications.

Surface evenness, the method of testing, and finishing of the surface shall comply with the
requirements specified in Section 21.10, Finishing Plastic Concrete.

Extending Existing Slabs

Existing slabs shall be extended by the Contractor in accordance with Section 21.23, Extending
Concrete Structures.

Prestressed Concrete Deck Panels

Where the Project requires the use of prestressed concrete deck panels, the Contractor shall profile
each  beam  to  determine  the  actual  camber,  or  sag,  of  the  beams  before  placing  the  panels.  To
obtain the required cover over the slab reinforcement, and the required slab thickness, the profile
grade line, panel elevation, and bearing seat elevations shall be adjusted, as needed. When a profile
grade line adjustment is necessary, the Contractor shall make adjustments over suitable increments,
depending on span lengths, so that the revised grade line will produce a uniform profile and good
riding  qualities.  Grade  adjustments  shall  be  approved  by  the  Engineer  prior  to  placement  by  the
Contractor. When adjusting the grade line, the actual beam camber shall be considered in adjacent
spans  or  slab  placements.  Abutment  back-  and  wing  wall  portions  shall  be  placed  after  the
Contractor adjusts the profile grade line.

21.7.6

Approach Slabs

Approach slabs consisting of cast-in-place concrete shall be furnished and installed by the
Contractor, as indicated in the Contract drawings and as directed by the Engineer. Concrete placed
at approach slabs shall consist of Class C40/20 concrete

— unless otherwise specified in the

Contract documents. All materials for the concrete in approach slabs shall comply with the
requirements of this chapter.

21.7.6.1

Approach Slab Construction

Concrete approach slabs shall be placed on an aggregate base course, as specified in Section 3.2.2
of Chapter 3, Pavement, of these Standard Specifications.

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All approach slab concrete shall be placed in accordance with the applicable clauses under this
chapter. Surface evenness and methods for testing and finishing the surface shall comply with the
requirements specified in Section 21.10, Finishing Plastic Concrete.

21.7.7

Blinding Concrete

Blinding concrete shall be furnished and installed by the Contractor, as indicated in the Contract
drawings, as specified herein, and as directed by the Engineer.

Blinding concrete shall be constructed with Class C15/20 concrete and shall comply with all
requirements of this chapter.

21.7.7.1

Blinding Concrete Construction

Construction of all blinding concrete shall comply with the requirements of this chapter, or as directed
by the Engineer.

21.7.8

Screed Concrete

Screed concrete shall be furnished and installed by the Contractor, as indicated in the Contract
drawings, as specified herein, and as directed by the Engineer.

The  screed  concrete  shall  consist  of  one  part  Sulfate  Resistant  Portland  Cement  (SRC)  to  three
parts sand by volume. The ingredients shall conform to and be mixed as specified for Class C40/20
concrete  in  Section  4.3  of  Chapter  4,  Concrete  Works,  of  these  Standard  Specifications.  The
concrete  substrate  onto  which  the  screed  is  to  be  applied  shall  be  broom-finished,  cleaned,  and
coated  with  proper  bonding  agent  prior  to  application  as  specified  in  this  chapter  and  Chapter  4,
Concrete Works, of these Standard Specifications.

21.7.8.1

Crack Control Additive

The screed concrete shall be mixed with a crack controlling additive of high performance
micropolypropylene fiber complying with ASTM C1116 / C1116M - 10a Type II at a mixing rate of
1.0 kg per 1 cubic meter of screed mix or as recommended by the Manufacturer and approved by
the Engineer. Mixing shall be in accordance with the M

anufacturer’s recommendation and as

approved by the Engineer.

21.7.9

Mass Concrete - Thermal Control

Mass concrete placement shall be defined as any pour in which the concrete being cast has
dimensions of 1.00 metre or greater in all three directions (x, y, and z). For all mass concrete pours,
the mix temperature shall not exceed 25

C as measured immediately prior to placement of the

concrete into the forms. Further, the Contractor shall be required to maintain a core temperature of
68

C or less and a temperature differential of 20 degrees or less between the interior and exterior

of all mass pour elements during curing.

Mass concrete construction shall conform to the requirement and recommendation specified in ACI
Publication 207.1R-05

“Guide to Mass Concrete” and ACI 207.2R-07” Report on Thermal and

Volume Change Effects on Cracking of Mass Concrete

”.

The Contractor shall provide temperature monitoring devices to record temperature development
between the interior and exterior of the element at points approved by the Engineer and shall monitor
the mass pours to measure temperature differential. Temperature monitoring shall continue until the
interior temperature is within a differential of 20

C with the lowest ambient temperature for a

maximum of two weeks.

A proper thermal control plan shall be submitted by the Contractor describing the procedures to be
used to minimize the temperature differentials and to be approved by the Engineer. The independent
thermal control plan shall be submitted during the concrete mix design stage, and shall include the
following:

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a. Concrete Mix: The mix design shall be optimized with supplementary cementitious

materials like GGBS, PFA, etc. to reduce the heat of hydration.

b. Mass Concrete: Placing methods and time of placement at hot & cold weather ,

control of concrete delivery and placement temperatures , monitoring the core and
ambient temperatures by sensing probes placed at appropriate locations, curing
methods to control temperature differentials, use of insulation, placing of concrete lifts
along with successive timings, water cooling or water retention methods etc.

c. Formwork: Wooden forms shall be used, delayed form removal, protruding steel bars

to be utilized as heat sinks to draw heat out of core concrete, etc.

d. Corrective Measures: Corrective measures shall be proposed in case of failure to

comply with the methodology and revised thermal control reports.

The Engineer shall be provided with a copy of each set of readings as they are taken and a
temperature chart for each mass pour element showing temperature readings vs. time. Prior to
placing any mass concrete on the Project, the Contractor shall submit for approval:

a. An analysis of the anticipated thermal developments within mass pour placements

using the proposed materials and casting methods.

b. A plan outlining specific measures to be taken to control the temperature differential

within the limits noted above.

c. Their proposed monitoring system.
d. If the Contractor is proposing a special concrete mix design as part of the temperature

control plan, this mix design shall also be submitted for

the Engineer’s review and

approval.

If monitoring indicates that the proposed measures are not controlling the concrete core temperature
below 68

C and the concrete temperature differential within the 20 degrees specified, the Contractor

shall make the necessary revisions to the plan and submit the revised plan for approval.

The Contractor shall assume all risks connected with the placing of mass pour concrete and approval
of the Contractor’s plan will in no way relieve the Contractor of the responsibility for satisfactory
results. Should any mass concrete placed under this specification proves unsatisfactory, the
Contractor will be required to make the necessary repairs or remove and replace the material at the
Contractor’s expense.

Accumulation of water on the surface due to any cause during compaction shall be prevented as far
as possible and any such water shall be removed before further concrete is placed.

All costs associated with special temperature controls for mass concrete placement shall be included
at the Contractor's expense, and shall be without additional specific compensation. Requirements
for control of temperatures in mass concrete pours included in this article shall be in addition to any
other applicable requirements found in the Contract plans and Contract documents.

21.7.10

Removal of Falsework and Forms

Falsework and forms are temporary works that shall comply with the requirements of Section 1.20,
Chapter 1, General Requirements of these standard specifications.

The Contractor shall not remove falsework or forms without the Engineer’s approval. Any implicit or
explicit permission in these specifications to remove falsework or forms shall not relieve the
Contractor of responsibilities regarding damages to the concrete works that result from the
Contractor’s removal of the falsework or forms.

To determine when to remove falsework and forms, the Contractor shall consider conditions that
influence the early strength of concrete, including the location and character of work structures,
weather, and materials used in concrete mixes.

To remove falsework and forms, the Contractor shall not use any methods that are likely to
overstress the concrete or damage concrete surfaces. The Contractor shall remove supports in a
way that uniformly and gradually applies stresses to a concrete work.

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After removing formwork, the Contractor shall promptly request the Engineer’s inspection of concrete
works and surfaces. The Contractor shall carry out any remedial treatment to surfaces that the
Engineer requests without delay. The Engineer may reject any concrete surface that the Contractor
treats before such inspection.

The following defects and conditions may require repair or cleaning:

1.  Crazing
2.  Cracks
3.  Spalls
4.  Pop outs
5.  Air Bubbles
6.  Honeycombing
7.  Holes left by rods and bolts
8.  Surface deficiencies that penetrate to the reinforcement
9.  Fins and other objectionable projections on the surface
10. Stains and discolorations that cannot be removed by cleaning

The Engineer may require the Contractor to remove and replace entire portions of defective concrete
that cannot be easily repaired or cleaned.

The Contractor shall remove falsework for arch bridges uniformly and gradually, beginning at the
crown and working toward the springing. At the same time, the Contractor shall remove the falsework
for adjacent arch spans.

Forms that support decks for box girders and forms in hollow abutments may remain in place when
no permanent access into such cells is available. Before reusing formwork, the Contractor shall
thoroughly clean it and make it ready to the satisfaction of the Engineer.

The Contractor shall remove forms that do not support the dead load of concrete members and forms
for railings and barriers 24 hours after the placement of concrete. Exposed concrete surfaces shall
be protected from damage.

After use and removal, forms and falsework shall remain the property of the Contractor. Work areas
shall be restored to their original or planned conditions and cleaned of all debris.

For structures of two or more spans, the sequence of falsework removal shall be as specified or
approved in Contract documents.

21.7.10.1 Time of Removal

The Contractor shall time the removal of formwork to best suit curing and to prevent elastic
shortening, shrinkage, or creep.

The Contractor shall not remove forms and supports until sufficient time has passed after concrete
placement, as indicated in Table 21-6.

Table 21-6: Time of removal

Structural member

Time of
Removal

Forms and falsework that provide support for the following structures:

•

Spans over than 4.3 metres (slab spans, pan girders, reinforced concrete

box (RCB) decks, or pier caps)

14 days

•

Spans of 4.3 metres or less (bridges decks on girders, RCB decks, and

diaphragms)

10 days

•

Pile bent pier caps that are not yet supporting girders

10 days

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Structural member

Time of
Removal

Forms that do not support the dead weight of concrete:

•

Side forms for abutments and pier caps, sides of beams, slabs,

walls, and columns (unloaded)

24 hours

•

Interior cells of box girders, railings, and barriers

12 hours

Special notes on project plans that detail the removal of forms and falsework under arches,
continuous spans, and other special structures including pre-stressed concrete beams shall have
precedence over the time limits for removal of forms and falsework shown in Table 21-6.

The Engineer may accelerate the removal for supporting forms or falsework (except those for
columns, walls, side forms for abutment, pier caps, railing and barriers), requesting such removal as
soon as concrete has attained 80 % of its specified strength.

Time of removal for forms and falsework must meet the following additional requirements:

1. Forms shall not be removed until concrete has sufficient strength to prevent damage to the

surface.

2. Falsework for post-tensioned portions of structures shall not be released until the prestressing

steel has been tensioned.

3. Falsework that supports any span of a continuous or rigid frame bridge shall not be released until

the aforementioned requirements have been satisfied for all of the structural concrete in that
span and in the adjacent portions of each adjoining span for a length equal to at least one-half
the length of the span for which falsework is to be released.

4. Unless other specifications or approvals apply, falsework shall be released before the placement

of railings, copings, or barriers for all types of bridges. For arch bridges, the time of falsework
release relative to the construction of elements of the bridge above the arch shall be as shown
on the plans or as directed by the Engineer.

21.7.10.2 Extent of Removal

The Contractor shall remove all falsework and forms except under the following conditions:

1. If portions of driven falsework piles are more than 300 mm below the subgrade within roadbeds,

more than 600 mm below the original ground or finished grade outside of roadbeds, or more than
600 mm below the established limits of any navigation channel

2.  If the removal of footing forms  would endanger the safety of cofferdams or other work
3.  If forms support enclosed cells where access is not provided
4.  If deck forms in the cells of box girder bridges do not interfere with the future installation of utilities

shown in Contract documents

21.8

Construction Joints

Construction joints shall be made only where specified in the Contract documents, or shown in the
pouring schedule, unless otherwise approved. All planned reinforcing steel shall extend
uninterrupted through joints. In the case of emergencies, the Contractor shall place the construction
joints as directed by the Engineer; and, if directed, additional reinforcing steel dowels shall be placed
across the joint. Such additional steel shall be furnished and placed at the Contractor's expense.
Injection of construction joints shall be carried out in accordance with Section 21.9.3.

21.8.1

Horizontal Joints

Generally, horizontal joints shall be made by pouring the concrete slightly above the grade of the
construction joint, and after the surface has reached its final set, the surface shall be prepared as

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outlined in Section 21.8.421.8.3, Bonding. Insert formwork shall be used to obtain neat, horizontal
lines.

21.8.2

Vertical Joints

Vertical joints shall be formed with substantial bulkheads or headers, as required. Feather-edged
joints shall not be permitted.

21.8.3

Bonding

Unless otherwise specified in the Contract documents, horizontal joints may be made without keys,
and vertical joints shall be constructed with shear keys. Surfaces of fresh concrete at horizontal
construction joints shall be rough-floated sufficiently to thoroughly consolidate the surface and left
intentionally in a roughened condition. Shear keys shall consist of formed depressions in the surface
covering approximately one-third of the contact surface. Key forms shall be bevelled so that removal
shall not damage the concrete.

All  construction  joints  shall  be  cleaned  of  surface  laitance,  curing  compounds,  and  other  foreign
materials  before  fresh  concrete  is  placed  against  the  surface  of  the  joint.  Abrasive  blast  or  other
approved  methods  shall  be  used  to  clean  horizontal  construction  joints  to  the  extent  that  clean
aggregate  is  exposed.  All  construction  joints  shall  be  flushed  with  water  and  allowed  to  dry  to  a
surface-dry condition immediately prior to placing concrete.

21.8.4

Bonding and Dowelling to Existing Structures

When the Contract documents specify that new concrete be bonded to existing concrete structures,
the existing concrete shall be cleaned and flushed, as specified in Section 21.8.3, Bonding. When
the Contract documents show reinforcing dowels grouted into holes drilled in the existing concrete
at such construction joints, the holes shall be drilled by methods that shall not shatter or damage the
concrete adjacent to the holes. Drilled-hole diameters shall measure 6 mm larger than the nominal
diameter of the dowels, unless shown otherwise in the Contract documents. Grout shall consist of a
neat,  cement  paste  created  from  Portland  cement  and  water,  with  water  content  that  shall  not
measure  more  than  0.36  litre/kg  of  cement.  Re-tempering  of  the  grout  shall  not  be  permitted.
Immediately  prior  to  placing  the  dowels,  the  Contractor  shall  clean  the  holes  of  dust  and  other
deleterious materials, and thoroughly saturate them with water and remove all free water, then the
holes shall be dried to a saturated surface-dry condition. Sufficient grout shall be placed in the holes
so that no voids remain after the dowels are inserted. Grout shall be cured for a period of at least
three days, or until dowels are encased in concrete.

When specified in the Contract documents, or approved by the Engineer, epoxy may be used in lieu
of Portland cement grout for the bonding of dowels in existing concrete. When used, epoxy shall be
mixed and placed in accordance with the Manufacturer's recommendations.

21.8.5

Forms at Construction Joints

When forms at construction joints overlap previously placed concrete, they shall be retightened
before depositing new concrete.

Straight bulkheads or grade stripes shall be the Contractor’s tool

for neatly forming the face edges of all joints that are exposed to view. If straight bulkheads or grade
stripes are not available, the Contractor may otherwise carefully finish the face edges true to line
and elevation.

21.8.6

Waterstops at Construction Joints

Waterstops shall be installed at all construction joints in accordance with Article 21.9.1.6 and Article
21.9.2.4.

21.9

Expansion and Contraction Joints

Expansion and contraction joints shall be constructed at the locations, and in accordance with the
details, specified in the Contract documents; and include open joints, filled joints, joints sealed with

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sealants or water stops, joints reinforced with steel armour plates or shapes, and joints with
combinations of each of these features.

When preformed elastomeric compression joint seals or bridge deck joint seal assemblies are
required, they shall conform to the requirements of Chapter 26, Bridge Deck Joint Systems.

21.9.1

Expansion and Contraction Joint Materials

21.9.1.1

Pre-moulded Expansion Joint Fillers

Pre-moulded fillers shall conform to one of the following specifications:

•

Specification for Preformed Expansion Joint Fillers for Concrete Paving and Structural

Construction, AASHTO M 213-01 (2010) (ASTM D1751 - 04(2008)).

•

Specification for Preformed Sponge Rubber and Cork Expansion Joint Fillers for Concrete

Paving and Structural Construction, AASHTO M 153-06 (R2011) (ASTM D1752 - 04a(2008)).
Type II (cork) shall not be used when resiliency is required.

•

Specification for Preformed Expansion Joint Filler for Concrete, AASHTO M 33-99 (2012)

(ASTM D994 / D994M - 11).

21.9.1.2

Polystyrene Board Fillers

Board  fillers  shall  be  expanded  polystyrene  with  a  minimum  flexural  strength  of  0.24  MPa,  as
determined by  ASTM C203 -  05a(2012) and compressive yield strengths measuring  between 0.1
MPa to 0.3 MPa at five percent compression. When specified in the Contract documents, or where
required to prevent damage during concrete placement, the surface of polystyrene board shall be
faced  with  3-mm  thick  hardboard  conforming  to  American  National  Standards  Institute  (ANSI)
A135.4. Density of the polystyrene board shall be as specified in the Contract documents.

21.9.1.3

Contraction Joint Material

Material placed in contraction joints shall consist of asphalt-saturated felt paper or another approved
bond-breaking material.

21.9.1.4

Pourable Joint Sealants

Pourable sealants placed along the top edges of contraction or filled expansion joints shall conform
to one of the following:

•

Hot-poured sealants shall conform to AASHTO M 282-99 (2012) (ASTM D3406 - 95(2006));

except when the sealant comes in contact with asphaltic material, then it shall conform to
AASHTO M301-01.

•

Cold-poured sealant shall be silicone-type, conforming to Federal Specification TT - S-1543,

Class A. Sealants shall be a one-part, low-modulus silicone rubber-type with an ultimate
elongation of 1,200%.

•

Polyethylene foam strips used when shown in the Contract documents shall consist of

commercial quality with a continuous, impervious, glazed top surface, suitable for retaining
the liquid sealant at the proper elevation in the joint while hardening.

21.9.1.5

Metal Armour

Expansion joint armour assemblies shall be fabricated from steel in conformance with the
requirements of Section 30.5 of Chapter 30, Miscellaneous Metal. Assemblies shall be accurately
fabricated and straightened at the shop after fabrication and galvanizing, as necessary, to conform
to the concrete section.

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21.9.1.6

External and Internal Waterstops

Waterstops shall consist of the type, size, and shape specified in the Contract documents. They shall
be dense, homogeneous, and without holes or other defects. Waterstops shall be furnished by a
manufacturer with a minimum of ten years experience in the Middle East.

Shop drawings for the waterstops network shall be submitted by the Contractor for the approval of
the Engineer. Samples of the proposed materials shall be submitted. Technical backup services and
supervision on site during the application of the waterstops shall be provided by the Manufacturer.

External waterstops in base slab expansion joints shall be minimum 350mm wide with four bulbs
and ten parallel lines of fins. The Centre box section shall be 25mm wide and flat to accept a filler
board. The waterstop shall have an outer nailing flange with reinforced and profiled edge to resist
tear when fixed to shuttering with double headed nails, and provide additional key when cast into the
concrete.

External waterstops in base slab construction and contraction joints shall be minimum 350mm wide
with four bulbs and ten parallel lines of fins. The waterstop shall incorporate a central fin, 22mm high,
as shutter stop. The waterstop shall have an outer nailing flange with a reinforced and profiled edge
to resist tear when fixed to shuttering with double headed nails, and provide additional key when
cast into the concrete.

Internal waterstops in wall and roof expansion joints shall have a centre box to accommodate
movement, be minimum 350mm wide with four bulbs and ten parallel lines of fins. The centre box
section shall be flat to accept a filler board. The web shall have a thickened central section to transfer
stresses to the centre bulbs. The waterstop shall have a reinforced eyeleted outer flange for secure
fixing of the waterstop into position.

Internal waterstops in wall and roof construction and contraction joints shall be minimum 350mm
wide with four bulbs and ten parallel lines of fins. The web shall have a thickened central section to
transfer stresses to the centre bulbs. The waterstop shall have a reinforced eyeleted outer flange for
secure fixing of the waterstop into position.

Waterstops shall only be supplied by manufacturers operating a BS EN ISO 9001 quality assurance
scheme.

Rubber Waterstops

Rubber waterstops shall be formed from synthetic rubber made exclusively from neoprene,
reinforcing carbon black, zinc oxide, polymerization agents, and softeners. This compound shall
contain not less than 70% by volume of neoprene. Tensile strengths shall not be less than 19 MPa
with an elongation at breaking of 600%. Shore durometer indication, or hardness, shall be between
50 and 60. Tensile strengths shall not be less than 65% of the original after seven days in air at a
temperature of 70 degrees Celsius, ±1 degree

— or after four days in oxygen at 70 degrees Celsius,

±1 degree, and 2 MPa pressure.

To ensure the production of a uniform section with a permissible variation in dimension of ±0.8 mm,
the Manufacturer shall form the rubber waterstops with an integral cross section in suitable moulds.
No splices will be permitted in straight strips. Additionally, strips and special connection pieces shall
be well cured in a manner that creates dense, homogeneous cross sections that are free from all
porosity. Junctions in the special connection pieces shall be full moulded. During the vulcanizing
period, the joints shall be securely held by suitable clamps. Materials at the splices shall be dense
and homogeneous throughout the cross section.

Polyvinyl Chloride Waterstops

Polyvinyl chloride (PVC) waterstops shall be manufactured by the extrusion process from an
elastomeric plastic compound, the basic resin that consists of PVC. These compounds shall contain
any additional resins, plasticizers, stabilizers, or other materials needed to ensure that, when the
material is compounded, it will meet the performance requirements given in this specification. No
reclaimed PVC or other material shall be used.

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Materials shall comply with the physical requirements presented in Table 21-7, when tested under
the indicated ASTM test method.

Table 21-7: ASTM test method requirements for PVC materials

Size

ASTM D5947 - 11

Water Absorption

ASTM D570 -
98(2010)e1

0.02

Tear Resistance

ASTM D624 - 00(2012)

39.40 N/mm

Specific Gravity

ASTM D792 - 08

1.40 maximum

Durometer Hardness

ASTM D2240 - 05(2010) 75 ± 5

Tensile Strength

ASTM D638 - 10

13.80 MPa
mini

Elongation

ASTM D638 - 10

350%

Cold Brittleness

ASTM D746 - 07

-37oC

Stiffness in Flexure

ASTM D747 - 10

4.8 MPa

Effect on Alkali after 7 days (Weight Change & Hardness
Change)

ASTM D543 - 06

+ 0.10%
+ 1 Point

Tensile strength after Accelerated Extraction

CRD-C 572-74

12.75 MPa

Elongation after Accelerated Extraction

CRD-C 572-74

350%

Copper Waterstops

Sheet copper shall conform to the specifications for copper sheet, strip, plate, and rolled bar;
AASHTO M 138M/M 138-08 (ASTM B152 / B152M - 09); and shall meet the embrittlement test of
Section 10 of AASHTO M 138M/M 138-08 (ASTM B152 / B152M - 09).

Testing of Waterstops Material

All waterstop materials shall be tested by the Manufacturer, either in company-owned or affiliated
laboratories

— or in a recognized commercial laboratory — and shall submit three certified copies

of the test results to the Engineer.

21.9.2

Expansion and Contraction Joint Installation

21.9.2.1

Open Joints

Open joints shall be constructed by the insertion and subsequent removal of a wood strip, metal
plate, or other approved material. Template insertion and removal shall be accomplished without
chipping or breaking concrete corners. When not protected by metal armour, open joints in decks
and sidewalks shall be finished with an edging tool. Upon completion of concrete finishing work, all
mortar and other debris shall be removed from open joints.

21.9.2.2

Filled Joints

When filled joints are specified in the Contract documents, pre-moulded-type fillers shall be used
unless polystyrene board is specifically called for. Filler for each joint shall consist of as few pieces
of material as possible. Abutting edges of filler material shall be accurately held in alignment with
each other and tightly fitted or taped, as necessary, to prevent the intrusion of grout. Joint filler
material shall be anchored to one side of the joint by waterproof adhesive or other methods so as to
prevent it from working out of the joint, but not interfere with the compression of the material.

21.9.2.3

Sealed Joints

Prior to the installation of pourable joint sealants, the Contractor shall remove all foreign material
from the joint, shall cut back the filler material to the depth shown or approved, and clean the surface
of the concrete that will be in contact with the sealant with light sandblasting. When required, a
polyethylene foam strip shall be placed in the joint to retain the sealant and isolate it from the filler
material. Sealant materials shall then be mixed and installed in accordance with the Manufacturer's
directions; and any material that fails to bond to the sides of the joint within 24 hours after placement
shall be removed and replaced by the Contractor.

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21.9.2.4

Waterstops

Waterstops shall be furnished and installed in accordance with the details indicated on the Contract
drawings, the provisions of this section, and as directed by the Engineer.

Waterstops shall conform to the cross section and to the minimum dimensions indicated on the
Contract drawings.

Adequate water stops of metal, rubber, or plastic shall be placed as specified in the Contract
documents. Where movement at the joint is provided for, the waterstops shall be of a type permitting
such movement without damage. They shall be spliced, welded, or soldered to form continuous
watertight joints.

No site welding of waterstops and no splices will be permitted in straight strips. Additionally, strips
and special connection pieces shall be well cured in a manner that creates dense, homogeneous
cross sections that are free from all porosity. All junctions in the special connection pieces shall be
fully moulded. During the vulcanizing period, the Contractor shall secure the joint with suitable
clasps. Materials at the splices shall be dense and homogeneous throughout the cross sections.

Field splices for rubber waterstops shall be either vulcanized, mechanical, using stainless steel parts;
or made with a splicing union of the same stock as the waterstop, at the option of the Contractor.

Field splices for PVC waterstops shall be performed by heat sealing the adjacent surfaces in
accordance with the Manufacturer's recommendations. A thermostatically controlled electric source
of heat shall be used to make all splices and shall sufficiently melt, but not char, the plastic.

The waterstop network shall provide an integral four bulb system with constant width throughout.
Standard intersections shall be used to accommodate changes in direction. On site jointing shall be
carried out using metal jigs provided by the Manufacturer to ensure alignment and continuity of
section.

To avoid bucking or distortion of the web or flange during waterstop installation, the Contractor shall
cut and splice them at changes in directions, as may be necessary.

Field splices shall develop water tightness equal to that of the unspliced material and have a tensile
strength of not less than 50 percent of the unspliced material.

Precautions shall be taken so that the waterstops shall be neither displaced nor damaged by
construction operations, or other means. While the waterstop is being embedded in concrete, the
Contractor shall keep all surfaces free from oil, grease, dried mortar

— or any other foreign matter.

Means shall be used to ensure that all portions of the waterstop designed for embedment shall be
tightly enclosed by dense concrete.

Waterstops shall be properly placed and tensioned prior to start concrete work. If, after placing the
concrete the waterstops are materially out of position or shape, the Contractor shall remove the
surrounding concrete, rest the waterstop, and replace the concrete

— at its own expense.

21.9.2.5

Expansion Joint Armour Assemblies

Armour assemblies shall be installed so the top surface matches the plane of the adjacent finished
concrete surface throughout the length of the assembly. Positive methods shall be employed in
placing the assemblies to keep them in correct position during the placing of the concrete. Openings
at expansion joints shall be that designated in the Contract documents at normal temperature, or as
directed by the Engineer for other temperatures; and, the Contractor shall take care to avoid
impairment of the clearance in any manner.

21.9.2.6

Sheet Packing, Preformed Pads, and Board Fillers

Tempered hardboard shall conform to Federal Specification LLL-B-810, Type II; and shall be smooth
on one side and plain. Hardboards shall measure at a minimum thickness of 3 mm, unless shown or
specified otherwise.

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Expanded polystyrene shall be a commercially available polystyrene board. Expanded polystyrene
shall have a flexural strength of 240 kPa, minimum, determined in conformance with the
requirements in ASTM C203 - 05a(2012) and compressive yield strengths of between 110 kPa and
275 kPa, at 5% compression.

When  shown  in  the  Contract  documents,  surfaces  of  expanded  polystyrene  shall  be  faced  with
hardboard,  which  shall  measure  at  a  minimum  thickness  of  3  mm,  conforming  to  Federal
Specification  LLL-B-810,  any  type.  Other  facing  materials  may  be  used,  provided  they  furnish
equivalent protection. Boards shall be held in place by nails, waterproof adhesives, or other means
approved by the Engineer.

21.9.3

Injection of Expansion and Construction Joints

Re-injectable PVC hoses comprising of a hollow core and lateral openings covered by neoprene
strips and webbed nylon mesh (or equivalent) shall be installed at all horizontal and vertical
expansion and construction joints, in all structural elements exposed to water such as base slab,
walls, and all underground structures as indicated in the Contract plans.

The outside diameter of the hose shall be a minimum of 24 mm with a longitudinal internal injection
hole diameter of 10 mm and discharge openings of 5 mm diameter at a maximum spacing of 300
mm centre to centre. The hose shall be placed to the total length of expansion and construction joints
with entry port and vent ends terminating in a junction box. The re-injectable hose shall be cleanable
and re-injectable. The hose shall be clamped into position with clips spaced at 250 mm apart.

21.9.3.1

Construction Joints

The concrete substrate along the length of the construction joint shall be free of debris and from any
form of contaminants. Sharp areas shall be grinded off and loose concrete shall be removed by the
Contractor.

The Contractor shall place the re-injectable hoses between the internal and external waterstops and
fix them firmly into the substrate.

Initial injection of construction joints shall be carried out by the Contractor before demobilizing the
dewatering  system  and  immediately  after  achieving  the  28  days  compressive  strength.  Approved
cementatious flowable  grout  shall  be  used for  injection.  Installation  of  hose  and  injection  of grout
shall be carried out exactly as per the  M

anufacturer’s instructions. Volumes of grout injected and

pressure used to inject shall be recorded. All injection hoses shall be flushed out after the above
mentioned injection is carried out to allow future re-injection.

21.9.3.2

Expansion Joints

The Contractor shall install and fix the re-injectable hoses on both edges of internal waterstop. For
all  expansions  joints  initial  injection  shall  be  carried  out  immediately  after  achieving  the  28  days
compressive  strength.  Approved  acrylic  gel  (or  equivalent),  having  ultra  low  viscosity,  high
expandability, strength, and accommodation of joint movements, shall be used. Installation of the
hose  and  injection  of  the  resin  shall  be  carried  out  as  per  the  M

anufacturer’s recommendations.

Volumes of acrylic gel injected and pressure used to inject shall be recorded. All injection hoses shall
be flushed out after the above mentioned injection is carried out to allow future re-injection.

21.9.3.3

Injection of Leaking Joints

The Contractor shall identify the leakage locations on the joints of the structure and re-inject hoses
satisfactorily in the leaking joints until all leaks have been stopped.

No additional payment will be made by the Owner for these items and they shall be placed at the
Contractor’s expense.

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21.10

Finishing Plastic Concrete

Unless otherwise specified in the Contract documents, after the Contractor has consolidated the
concrete

— and prior to the application of cure — all surfaces of concrete that are not placed against

forms shall be struck-off to the planned elevation or slope and the surface finished by floating with a
wooden float sufficiently to seal the surface. While the concrete is still in a workable state, the
Contractor shall carefully tool all expansion and construction joints with an edger. Joint filler shall be
left exposed

21.10.1

Roadway Concrete Surface Finish

All bridge decks, approach slabs, and other concrete surfaces used by traffic shall be finished to a
smooth skid-resistant surface in accordance with this chapter. During finishing operations, the
Contractor shall provide suitable and adequate work bridges for proper performance of the work,
including the application of fog sprays and curing compound, and for inspecting the work.

21.10.1.1 Striking off and Floating

After  the  concrete  is  placed  and  consolidated  according  to  the  specifications  in  Section  21.7,
Handling  and  Placing  Concrete,  bridge  decks  or  top  slabs  of  structures  shall  be  finished  by  the
Contractor  using  approved  power-driven  finishing  machines.  If  the  Engineer  approves  them,  the
Contractor may use hand-finishing methods for short bridges measuring 15 m or less in length

— or

for irregular areas where the use of a machine would be impractical.

All surfaces shall be struck-off by equipment supported by and travelling on rails or headers. Rails,
headers, and strike-off equipment shall be of sufficient strength and be adjusted so that the concrete
surface, after strike-off, will conform to the planned profile and cross section. Rails or headers shall
be set on non-yielding supports and shall be completely in place and firmly secured for the scheduled
length  for  concrete  placement  before  placing  of  concrete  will  be  permitted.  Rails  for  finishing
machines  shall  extend  beyond  both  ends  of  the  scheduled  length  for  concrete  placement  for  a
sufficient distance to permit the float of the finishing machine to fully clear the concrete to be placed.
Rails or headers shall be adjustable for elevation and shall be set to allow for anticipated settlement,
camber,  and  deflection  of  falsework

— as necessary — to obtain a finished surface true to the

required grade and cross section. They shall be of a type and shall be so installed that no springing
or deflection will occur under the weight of the finishing equipment and shall be so located that
finishing equipment may operate without interruption over the entire surface. Rails or headers shall
be adjusted, as necessary, to correct for unanticipated settlement or deflection that may occur during
finishing operations. If rail supports are located within the area where concrete is being placed, the
Contractor shall remove them to at least 50 mm below the finished surface, as soon as they are no
longer needed, and shall fill the void with fresh concrete.

Before the delivery of concrete, the finishing machine, or the hand-operated strike-off tool, shall be
operated over the entire area to check for excessive rail deflections and for proper deck thickness
and cover on reinforcing steel. This check will also verify operation of all equipment. Any necessary
corrections shall be made before beginning concrete placement.

Concrete finishing machine shall include, but not by way of limitation, the following:

a. Finishing machine shall be of a type approved by the Engineer, power driven and equipped

with at least two screeds, and shall be fully and accurately adjustable to produce a crowned
or flat surface. The finishing machine shall be designed and operated to strike-off, screed,
and consolidate and shall have a minimum of one reciprocating, non-vibratory screed.
Finishing machines shall have ample strength and sufficient power and be so geared as to
operate consistently, regularly, and smoothly.

b. Concrete finisher floats shall be attached to the finishing machine. They shall be equipped

with independent wheels that ride on the rails and shall be of sufficient weight as to not flex
under the pressure of the concrete. Floats shall be easily adjustable from crown to flat and
shall be a minimum of 76 cm in length with a minimum 60 cm in contact with the concrete.
Float pans shall be suspended from the frame, float freely on the concrete and shall be

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capable of being adjusted in both height and width. Float pans, once adjusted, shall be
equipped hydraulically, or by other suitable means so that they may be raised from the
operator's platform and when lowered shall automatically return to their pre-set positions.

c. Finishing machines shall be so constructed that the travel of the floating mechanism can be

adjusted to conform to the concrete cross section indicated in the Contract drawings or
formed by the finishing machine.

d. Concrete bridge roadway decks and approach slabs shall be struck off and screeded with a

finishing machine; the use of a vibratory screed shall not be permitted.

e. Consolidating methods for the concrete shall be as approved by the Engineer; and the use

of vibrating equipment shall be subject to the approval of the Engineer.

Finishing of concrete placed in bridge decks shall consist of striking off the surface of the concrete
as placed, floating the surface so struck off, and finishing as specified herein.

Concrete placement in bridge roadway decks shall not be permitted until the Engineer is satisfied
that the rate of producing and placing concrete will be sufficient to complete the proposed operations
within the scheduled time, that experienced finishing machine operators are employed to finish the
deck, and that fogging equipment and all necessary finishing tools and equipment are on-site and in
satisfactory condition for use. Finishing machines shall be set up sufficiently in advance of use to
permit inspection by the Engineer during the daylight hours before each pour.

All concrete on the bridge decks and approach slabs shall be formed and placed by the Contractor
to comply with all lines, levels, and profiles

— as indicated in the Contract drawings. This process

shall include all depressions or notches to receive expansion joints, as indicated and as specified in
Section 21.9, Expansion and Contraction Joints.

Immediately prior to placing bridge deck concrete or approach slabs, the Contractor shall check all
forms, falsework, and wedges and shall make all necessary adjustments. Care shall be exercised to
ensure that settlement and deflection, due to the added weight of the bridge deck concrete, shall be
a minimum. Suitable means, such as telltales, shall be provided by the Contractor to readily permit
measurement by the Engineer of settlement and deflection as it occurs.

If settlement, or other unanticipated events occur, which in the opinion of the Engineer shall prevent
obtaining  bridge  deck  or  approach  slabs  that  comply  with  the  requirements  of  these  Standard
Specifications,  placing  of  deck  concrete  shall  be  discontinued  until  corrective  measures  that  are
satisfactory  to  the  Engineer  are  provided.  If  the  Contractor  fails  to  provide  satisfactory  measures
prior to initial set of the concrete in the affected area, the placing of concrete shall be discontinued
and a bulkhead installed at a location determined by the Engineer. All concrete in place beyond the
bulkhead shall be removed.

Concrete for bridge decks shall be placed in a uniform heading approximately normal to the structure
centreline or, in the case of screeds supported on transverse headers, parallel to the centreline

—

as directed by the Engineer. Concrete placing rates shall be limited to that which can be finished
before the beginning of initial set.

Immediately after the concrete has been placed and consolidated, the surface shall be struck off with
the finishing machine until the required surface is obtained.

Finishing machines shall go over each area of the surface as many times as required to obtain the
required profile and cross section. A slight excess of concrete shall be kept in front of the cutting
edge of the screed at all times. This excess shall be carried all the way to the edge of the pour or
form and shall not be worked into the slab. It shall be wasted.

After strike-off, the surface shall be finished with a float, roller, or other approved device to remove
any local irregularities and to leave sufficient mortar at the surface of the concrete for later texturing.

During finishing operations, excess water, laitance, or foreign materials brought to the surface during
the course of the finishing operations shall not be reworked into the slab, but shall be removed
immediately upon appearance by means of a squeegee or straightedge drawn from the centre of the
slab toward either edge.

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Adding water to the concrete surface to assist in finishing operations shall not be permitted to avoid
shrinkage cracks.

Prior to their use, the strike-off method and equipment shall be subject to approval by the Engineer,
who  can  withdraw  his  approval  if  performance  is  not  satisfactory.  Selected  equipment  shall  be
capable  of  finishing  roadway  decks  within  the  surface  tolerances  set  forth  in  these  standard
specifications. Improper adjustment  and  operation  that  results  in  unsatisfactory  consolidation  and
smoothness shall be corrected immediately. Unsatisfactory performance may be cause for rejection
of the equipment and removal of the in-place concrete.

In areas inaccessible to a finishing machine

— and where permitted by the Engineer — the

Contractor may float the roadway or approach slab surfaces to a smooth, uniform surface following
the completion of the strike-off by hand methods by means of floats measuring 3 m or more in length.
When a finishing machine is used, the finished surface shall be floated in a similar manner

— unless

otherwise directed by the Engineer. Adequate floats shall be used to remove roughness and minor
irregularities left by the strike board or finishing machine and to seal the concrete surface. Excessive
working of the concrete surface shall not be permitted by the Engineer. All floats shall be used in
such a manner that each transverse pass overlaps the previous pass by a distance of at least one-
half the length of the float.

When hand-operated float boards are used, they shall measure 3.5 m to 4.5 m long, and shall be
ribbed and trussed to provide a rigid float. They shall also be equipped with adjustable handles at
each end. Float shall consist of wood not less than 25 mm thick and a minimum of 200 mm wide.
Adjusting screws spaced at no more than 600 mm on centres shall be provided between the float
and the rib. Float boards shall be maintained free of twist and true at all times.

Hand-operated float boards shall be operated from transverse finishing bridges, which shall
completely span the bridge roadway deck or approach slab area being floated, and a sufficient
number of finishing bridges shall be provided to permit operation of the floats without undue delay.
Not less than two transverse finishing bridges shall be provided when hand-operated float boards
are used. When a finishing machine is used for longitudinal floating, one finishing bridge equivalent
to the transverse finishing bridge specified herein shall be furnished for use by the Engineer.

All finishing bridges shall be of rigid construction and shall be free of wobble and spring when used
by the operators of longitudinal floats. They shall also be easily moved.

21.10.1.2 Straight Edging

After the floating has been completed, but while the concrete is still plastic, the slab surface shall be
tested with a 3-m metal straightedge, which shall be held in contact with the surface in successive
positions parallel to the bridge roadway deck or approach slab centreline and then at right-angles.
Testing shall occur throughout the whole area, from one side of the deck or slab to the other. These
tests shall be in successive stages of not more than one-half the length of the straightedge. Any
depressions found shall be filled at once with freshly mixed concrete, struck off, consolidated, and
refinished. High areas shall be cut down and refinished. Testing and refinishing shall continue until
the entire surface is found to be free from deviations of more than 3 mm from the testing edge of the
straightedge. For deck surfaces that are to be overlaid with 25 mm or more of another material, such
deviation shall not exceed 10 mm in 3 m. Deviations in excess of these requirements shall be
corrected before the concrete sets.

Allowances shall be made for crown, camber, and vertical curvature. Any straight-edging and
corrective work performed on the plastic concrete shall not relieve the Contractor of testing the
smoothness requirements on the hardened concrete, as outlined hereinafter.

21.10.1.3 Texturing

Surfaces shall be given a skid-resistant texture by either burlap or carpet dragging, brooming, tinning,
or by a combination of these methods. Such equipment required to produce the final surface texture
shall be secured to the finishing machine. Texturing operations shall be so executed that the surface
is uniform in appearance and free from rough and porous spots, irregularities, and depressions.

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Employed methods shall be as specified in the Contract documents, or as approved by the Engineer.
Surfaces that are to be covered with a waterproofing membrane deck seal shall not be coarse
textured, but rather finished to a smooth surface, free of mortar ridges and other projections.

This operation shall be done after floating and at such time, and in such manner, that the desired
texture will be achieved while minimizing displacement of the larger aggregate particles.

Dragged

If the surface texture is to be a drag finish, the surface shall be finished by dragging a seamless strip
of damp burlap over the full width of the surface. Sufficient layers of burlap made up of sufficient
lengths shall create the burlap drag that will connect with the concrete to slighting groove the surface.
It shall be moved forward with a minimum bow of the lead edge. Drags shall be kept damp, clean,
and free of particles of hardened concrete. As an alternative to burlap, the Engineer may approve or
direct that carpet or artificial turf of an approved type and size be substituted.

Broomed

If the Contract documents require the surface texture to consist of a broom finish, the surface shall
be broomed when the concrete has hardened sufficiently. Brooms shall be of an approved type and
strokes shall be square across the slab, from edge to edge, with adjacent strokes slightly overlapped.
Strokes  shall  be  made  by  drawing  the  broom  without  tearing  the  concrete  but  producing  regular
corrugations  not  more  than  3  mm  in  depth.  Surfaces,  as  thus finished,  shall  be  free from  porous
spots,  irregularities,  depressions,  and  small  pockets  or  rough  spots  that  may  be  caused  by
accidentally  disturbing  particles  of  coarse  aggregate  embedded  near  the  surface  during  the  final
brooming operation.

Tined

If the surface is to be tined, the tinning shall be in a transverse direction using a wire broom, comb,
or finned-float having a single row of tines or fins. Tinning grooves shall be between 1.5 mm and 5
mm wide and between 3 mm and 5 mm deep, spaced 12 mm to 20 mm on centres. Tinning shall be
discontinued 300 mm from the curb line on bridge decks. Areas adjacent to the curbs shall be given
a light broom finish longitudinally. As an alternative, tinning may be achieved using an approved
machine designed specifically for tinning or grooving concrete pavements.

21.10.1.4 Surface Testing and Correction

After the concrete has hardened, the Engineer will inspect finished deck roadway surfaces that shall
not be overlain with a wearing surface. Any variations in the surface that exceed 3 mm from a 3 m
straightedge will be marked and corrected by the Contractor by the use of concrete planning or
grooving equipment that produces a textured surface equal in roughness to the surrounding
unground concrete without shattering or otherwise damaging the remaining concrete.

21.10.2

Pedestrian Walkway Surface Finish

After placement of the concrete for sidewalks and decks of pedestrian structures, it shall be
consolidated and the surface shall be struck off by means of a strike board and floated with wooden
or cork float. If directed, the surface shall then be lightly broomed in a transverse direction. An edging
tool shall be used on edges and expansion joints. Surfaces shall not vary more than 3 mm under a
1.5 m straightedge and shall have a granular or matte texture that shall not be slippery when wet.

Sidewalk surfaces shall be laid out in blocks with an approved grooving tool, as specified in the
Contract documents

— or as directed by the Engineer.

21.10.3

Trowelled and Brushed Finish

Surfaces that are specified in the Contract documents to be trowelled shall first be finished as
specified under Section 21.10, Finishing Plastic Concrete. Then, after the concrete is partially set,

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the surface shall be finished to a smooth surface by trowelling with a steel trowel until a slick surface
that is free of bleed water is produced and then brushed with a fine brush using parallel strokes.

21.10.4

Surfaces under Bearings

When metallic masonry plates are placed directly on the concrete, or on filler material less than 3
mm thick, the surface shall first be finished with a float finish. After the concrete has set, the area
that will be in contact with the masonry plate shall be ground to provide full and even bearing. When
such plates are set on filler material between 3 mm and 12 mm thick, the concrete surface shall be
steel-trowel finished without brushing and the flatness of the finished surface shall not vary from a
straightedge laid on the surface in any direction within the limits of the masonry plate by more than
1.5 mm. Surfaces that fail to conform to the required flatness shall be ground until acceptable.

Surfaces under elastomeric bearings and under metallic masonry plates that are supported on
mortar or filler pads measuring 12 mm or greater in thickness shall be finished by wood floating to a
flat and even surface free of ridges.

21.11

Curing Concrete

All newly placed concrete shall be cured so as to prevent loss of water by use of one or more of the
methods specified herein. Except for high-performance concrete (HPC) used in cast-in-place
construction

— where performance criteria in addition to concrete compressive strengths are

specified

— curing shall commence immediately after the free water has left the surface and finishing

operations are completed. For HPC, water curing shall commence immediately after finishing
operations are complete. If the surface of the concrete begins to dry before the selected cure method
can be applied, the surface of the concrete shall be kept moist by a fog spray applied so as not to
damage the surface.

Curing by other than waterproof cover, steam, or radiant-heat methods with precast concrete shall
continue uninterrupted for seven days

— except for when pozzolans in excess of 10 percent, by

weight, of the Portland cement are used in the mix. When such pozzolans are used, the curing period
shall be 10 days with an appropriate curing suitable for pozzolans such as the insulated curing, all
as per approved thermal control plan. For other than top slabs of structures serving as finished
pavements and HPC concrete, the above curing periods may be reduced and curing terminated
when test cubes cured under the same conditions as the structure indicate that concrete strengths
of at least 70% of that specified have been reached.

When deemed necessary by the Engineer during periods of hot weather, water shall be applied to
concrete surfaces being cured by the liquid membrane method or by the forms-in-place method, until
the Engineer determines that a cooling effect is no longer required. Such application of water shall
be at no cost to the Owner.

21.11.1

Curing Concrete Materials

21.11.1.1 Water

Water shall conform to the requirements of Section 4.3.8 of Chapter 4, Concrete Works, of these
Standard Specifications.

21.11.1.2 Liquid Membranes

Liquid membrane-forming compounds for curing concrete shall conform to the requirements of
AASHTO M 148-05 (ASTM C309 - 11).

21.11.1.3 Waterproof Sheet Materials

Waterproof paper, polyethylene film, and white burlap polyethylene sheets shall conform to the
requirements of AASHTO M 171-05 (ASTM C171 - 07).

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21.11.2

Curing Concrete Methods

21.11.2.1 Forms-in-place Method

Formed surfaces of concrete may be cured by retaining the forms in place without loosening for the
required time.

21.11.2.2 Water Method

For this method, concrete surfaces shall be kept continuously wet by ponding, spraying, or covering
with materials that are kept continuously and thoroughly wet. Such materials may consist of cotton
mats, multiple layers of burlap, or other approved materials that do not discolour or otherwise
damage the concrete.

21.11.2.3 Liquid-membrane Curing Compound Method

This method shall not be used on surfaces where a rubbed finish is required or on surfaces of
construction joints, unless it is removed by sand blasting prior to placement of concrete against the
joint. Type 2, white pigmented, liquid membranes may be used only on the surfaces of bridge decks,
on surfaces that shall not be exposed to view in the completed work, or on surfaces where their use
has been approved by the Engineer.

When membrane curing is used, the exposed concrete shall be thoroughly sealed immediately after
the free water has left the surface. Formed surfaces shall be sealed immediately after the forms are
removed and necessary finishing has completed. These solutions shall be applied by power-
operated atomizing spray equipment in one or two separate applications. Hand-operated sprayers
may be used for coating small areas. Membrane solutions containing pigments shall be thoroughly
mixed prior to use and agitated during application. If the solution is applied in two increments, the
second application shall follow the first application within 30 minutes. To ensure a uniform coverage
at the rate of 0.27 litre/m

, the Contractor shall provide satisfactory equipment together with the

means to properly control and assure the direct application of the curing solution on the concrete
surface.

If rain falls on the newly coated concrete before the film has dried sufficiently to resist damage, or if
the film is damaged in any other manner during the curing period, a new coat of the solution shall be
applied to the affected portions equal in curing value to that specified above.

21.11.2.4 Waterproof Cover Method

This method shall cover the surface with a waterproof sheet material so as to prevent moisture loss
from the concrete. It may be used only when the covering can be secured adequately to prevent
moisture loss.

During installation, concrete shall be wet at the time the cover is installed; the sheets shall be of the
widest practicable width; adjacent sheets shall overlap a minimum of 150 mm and shall be tightly
sealed with pressure sensitive tape, mastic, glue, or other approved methods to form a complete
waterproof cover of the entire concrete surface. Waterproof sheets shall be secured so that wind
shall not displace it. Shall any portion of the sheets be broken or damaged before expiration of the
curing period, the broken or damaged portions shall be immediately repaired. Sections that have lost
their waterproof qualities shall not be used.

21.11.2.5 Steam or Radiant-heat Curing Method

This method may be used only for precast concrete members manufactured in established plants.

Steam curing or radiant-heat curing shall be done under a suitable enclosure to contain the live
steam or the heat. Steam shall be low-pressure and saturated. Temperature recording devices shall
be employed to verify that temperatures are uniform throughout the enclosure and within the limits
specified in the Contract documents. When HPC is used in prestressed concrete members

— where

a concrete compressive strength greater than 41.4 MPa is specified

— the Contractor shall place

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temperature-sensing devices within the concrete to verify that temperatures are uniform and within
the limits specified.

Initial applications of the steam, or of the heat, shall not occur prior to initial set of the concrete except
to maintain the temperature within the curing chamber above the specified minimum temperature.
Initial set times may be determined by the Standard Method of Test for Time of Setting of Concrete
Mixtures by Penetration Resistance, AASHTO T 197M/T 197-11 (ASTM C403 / C403M - 08).

During the waiting period, the temperature within the curing chamber shall not be less than 10
degrees Celsius and live steam, or radiant heat, may be used to maintain the curing chamber at the
proper minimum temperature. During this period, the concrete shall be kept wet.

Application of live steam shall not be directed on the concrete or on the forms so as to cause localized
high  temperatures.  During  the  initial  application  of  live  steam  or  of  radiant  heat,  the  temperature
within the concrete shall increase at an average rate not exceeding  22 degrees Celsius per hour
until the curing temperature is reached. Maximum curing temperatures within the concrete shall not
exceed 71 degrees Celsius and shall be held until the concrete has reached the desired strength. In
discontinuing the steam application, the concrete temperature shall not decrease at a rate to exceed
22 degrees Celsius per hour until a temperature of 11 degrees Celsius above the temperature of the
air to which the concrete will be exposed has been reached.

Radiant heat may be applied by means of pipes circulating steam, hot oil, or hot water

— or by

electric heating elements. Radiant-heat curing shall be done under a suitable enclosure to contain
the heat, and moisture loss shall be minimized by covering all exposed concrete surfaces with plastic
sheeting or by applying an approved liquid-membrane curing compound to all exposed concrete
surfaces. Top surfaces of concrete members to be used in composite construction shall be clear of
residue of the membrane curing compound so as not to reduce bonds below design limits. Surfaces
of concrete members to which other materials will be bonded in the finished structure shall be clear
of residue of the membrane curing compound so as not to reduce bond below design limits.

For prestressed members, the transfer of the stressing force to the concrete shall be accomplished
immediately after the steam or heat curing has been discontinued.

21.11.2.6 Insulated Curing Method

The insulated curing method shall be in accordance of the requirements of Article 4.4.2.6 of Chapter
4, Concrete Works, of these standard specifications.

21.11.3

Bridge Decks

Top  surfaces  of  bridge  decks  shall  be  cured  by  a  combination  of  the  liquid-membrane  curing
compound method and the water method, and/or insulated curing method. Liquid membranes shall
be  Type  2,  as  defined  in  AASHTO  M  148-05  (ASTM  C309  -  11),  white  pigmented,  and  shall  be
applied from finishing bridges progressively and immediately after finishing operations are complete
on  each  portion  of  the  deck.  Water  cures  shall  be  applied  not  later  than  four  hours  after  the
completion of deck finishing or for portions of the decks on which finishing is completed.

HPC, where performance criteria in addition to concrete compressive strengths are specified, tends
to have little bleed, especially when the low-water to cementitious materials ratio is used with mineral
admixtures.  Additional  performance  criteria  may  include  shrinkage,  chloride  permeability,  de-icer
scaling resistance, abrasion resistance, or heat of hydration. As a result, the evaporation protection
of  the  bleed  water  on  the  fresh  concrete  is  lost.  Therefore,  when  HPC  is  used  in  cast-in-place
construction of bridge decks, water cure shall be applied immediately after the finishing of any portion
of the deck is complete and shall remain in place for a minimum period of seven days irrespective of
concrete  strength.  If  conditions  prevent  immediate  application  of  the  water  cure,  an  evaporation
retardant  shall  be  applied  immediately  after  completion  of  finishing  or  fogging  shall  be  used  to
maintain  a  high,  relative  humidity  above  the  concrete  to  prevent  drying  of  the  concrete  surface.
Following the water-cure period, liquid-membrane curing compound may be applied to extend the
curing period.

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21.12

Finishing Formed Concrete Surfaces

Surface finishes for formed concrete surfaces shall be classified as follows:

•

Class 1: Ordinary surface finish

•

Class 2: Rubbed finish

•

Class 3: Tooled finish

•

Class 4: Sandblast finish

•

Class 5: Wire brush or scrubbed finish

All concrete shall be given a Class 1 finish and, in addition, if further finishing is required, such other
type of finish as is specified.

If not otherwise specified in the Contract documents, exposed surfaces of piers, barriers, parapets,
curbs, underside of copings, backwalls above bridge seats and such other surfaces where smooth,
uniform surfaces are specified except the soffits of superstructures and the interior faces and
bottoms of concrete girders shall be given a Class 2 finish.

Class 3, 4, or 5 finishes shall be applied only where specified in the Contract documents.

The surface finish on piers shall include all exposed surfaces below the bridge seat to 300 mm below
the finish ground line.

21.12.1

Class 1: Ordinary Surface Finish

Immediately following the removal of forms, the Contractor shall remove all fins and irregular
projections from all surfaces that are to be exposed or waterproofed. Bulges and offsets in such
surfaces shall be removed with carborundum stones or discs.

Localized, poorly bonded rock pockets or  honeycombed concrete shall be removed and replaced
with  sound  concrete  or packed mortar,  as  specified  in  Section  21.18,  Mortar  and Grout. If,  in the
opinion of the Engineer, rock pockets are of such an extent or character as to affect the strength of
the structure materially or to endanger the life of the steel reinforcement, the Engineer may declare
the  concrete  defective  and  require  the  removal  and  replacement  of  the  portions  of  the  structure
affected.

On all surfaces, the cavities produced by form ties; other holes, broken corners, or edges; and other
defects shall be thoroughly cleaned and, after having been thoroughly saturated with water, shall be
carefully pointed and trued with a mortar conforming to Section 21.18. For exposed surfaces, white
cement  shall  be  added  to  the  mortar  in  an  amount  sufficient  to  result  in  a  patch  that,  when  dry,
matches the surrounding concrete. Mortar used in pointing shall be not more than one hour old; and
the  concrete  shall  be  rubbed,  if  required,  or  the  cure  continued  as  specified  in  Section  21.10,
Finishing  Plastic  Concrete.  Construction  and  expansion  joints  in  the  completed  work  shall  be  left
carefully tooled and free of mortar and concrete. Joint fillers shall be left exposed for the full length
with clean and true edges.

Resulting surfaces shall be true and uniform. Appearances of repaired surfaces that are not
satisfactory shall be rubbed as specified in Section 21.12.2, Class 2: Rubbed Finish.

21.12.2

Class 2: Rubbed Finish

After the removal of forms, the rubbing of concrete shall begin as its condition will permit. Immediately
before starting this work, the concrete shall be thoroughly saturated with water. Sufficient time shall
have  elapsed  before  the  wetting  down  to  allow  the  mortar  used  in  the  pointing  of  rod  holes  and
defects  to  thoroughly  set.  Surfaces  to  be  finished  shall  be  rubbed  with  a  medium-coarse
carborundum stone, using a small amount of mortar, which shall be composed of cement and fine
sand, mixed in proportions used in the concrete being finished. Rubbing shall be continued until form
marks,  projections,  and  irregularities  have  been  removed;  voids  have  been  filled;  and  a  uniform
surface has been obtained. Pastes produced by this rubbing shall be left in place.

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After the completion of additional work that could affect the surface, the final finish shall be obtained
by rubbing with a fine carborundum stone and water. This rubbing shall be continued until the entire
surface is of a smooth texture and uniform colour.

After the final rubbing is completed and the surface has dried, it shall be rubbed with burlap to remove
loose powder and shall be left free from all unsound patches, paste, powder, and objectionable
marks.

When metal, fibre, lined, or plywood forms in good condition are used, the requirement for a Class
2 finish may be waived by the Engineer when the uniformity of colour and texture obtained with Class
1 finishing are essentially equal to that which could be attained with the application of a Class 2
finishing. In such cases, grinding with powered disc grinders or light sandblasting with fine sand or
other means approved by the Engineer may be utilized in conjunction with Class 1 finishing.

21.12.3

Class 3: Tooled Finish

Finish of this character for panels and other like work may be secured by the use of a bush hammer,
pick, crandall, or other approved tool. Air tools, preferably, shall be employed. No tooling shall be
done until the concrete has set for at least 14 days and as much longer as may be necessary to
prevent the aggregate particles from being picked out of the surface.

21.12.4

Class 4: Sandblasted Finish

Thoroughly cured concrete surfaces shall be sandblasted with hard, sharp sand to produce an even,
fine-grained surface in which the mortar has been cut away, leaving the aggregate exposed.

21.12.5

Class 5: Wire-brushed or Scrubbed Finish

As soon as the forms are removed, and while the concrete is still comparatively green, the Contractor
shall thoroughly and evenly scrub the surface with stiff wire or fibre brushes, using a solution of
muriatic acid in the proportion of one-part acid to four parts water by volume until the cement film or
surface is completely removed and the aggregate particles are exposed. This process shall leave
an even, pebbled texture that presents an appearance grading from that of fine granite to course
conglomerate

— depending upon the size and grading of the aggregate used. When the scrubbing

has progressed sufficiently to produce the texture desired, the entire surface shall be thoroughly
washed with water to which a small amount of ammonia has been added, to remove all traces of
acid.

21.12.6

Concrete Architectural Rustication

Concrete architectural rustication in piers, abutments, wingwalls and retaining walls shall be
constructed as indicated on the Contract plans, as specified herein, or as directed by the Engineer.

Concrete architectural rustication which shall include but not be limited to concrete form liners, rough
texture finish, or any finishes shown on the Contract plans, in piers, abutments, wingwalls and
retaining walls is a decorative treatment and as such is not designed to support any superimposed
loads during construction or upon completion of the Works.

21.12.6.1 Materials

All materials shall comply with the requirements of Section 4.3 of Chapter 4, Concrete Works, of
these Standard Specifications, and this chapter.

21.12.6.2 Formwork

Formwork  for  the  pier,  wingwall,  and  abutment  rustication  shall  be  constructed  of  fibreglass  or
approved  metal.  The  Contractor  shall  submit  shop  drawings  of  his  proposed  formwork  to  the
Engineer  for  approval  in  accordance  with  the  requirements  of  the  Contract  documents.  The  form
release oil shall be nonstaining.

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