Abu Dhabi, United Arab Emirates. STANDARD CONSTRUCTION SPECIFICATIONS (PART 1 - ROADS, Second Edition 2020)

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3. Filling Baskets

Kinks and folds in the wire mesh shall be removed prior to filling the gabion cages, which
shall be aligned per the Contract plans and then filled with stone placed and compacted to
meet the unit weight requirements of Paragraph 4 below.

Stone  shall  be  placed  in  compacted  layers  not  more  than  350  mm  deep  then  tamped  or
vibrated. If cross-connecting wires are required, the Contractor shall adjust the number and
depth  of  layers  so  that  wires  occur  between  the  compacted  layers  of  stone.  Internal
connecting wires shall be placed in each unrestrained exterior basket cell greater than 0.3 m
high,  including  interior  basket  cells  left  temporarily  unrestrained.  Internal  connecting  wires
shall be placed concurrently with rock placement.

Stone shall be placed in close contact in the unit to minimise voids. Gabion cages may be
filled by machine with sufficient hand work to accomplish requirements of this specification.
Exposed face or faces shall be hand-placed using selected stones to prevent bulging of the
gabion cell and to improve appearance.

Care shall be taken to protect the vertical panels and diaphragms from being bent during
filling operations. Last lifts of stone in each cell shall be level with the top of the gabion to
properly close the lid and provide an even surface for the next course.

4. Unit Weight Requirements and Test

One unit weight test shall be conducted by the Contractor to test for each 380 m3 of gabions
placed. Specified frequencies of the provided tests may be reduced by the Engineer,
provided the specified minimum unit weight has been consistently achieved.

Either of the following unit weight tests shall be conducted to prove the density of completed
gabions:

i. A filled gabion basket shall be selected from the completed structure and weighed

ii. A gabion basket shall be filled with stone from a loaded truck that has been weighed.

After filling, the truck and unused stone shall be weighed again. Differences between the
weights shall be used to determine the weight per m

of the stone in the gabion.

Minimum unit weights of the filled gabion basket shall be 1,600 kg/m3. Should the unit weight
be less than required, the Engineer shall reject the gabion and require the Contractor to pass
additional unit weight tests before completing other gabions.

5. Gabion Basket Erection

Empty gabion baskets shall be placed on the foundation and adjacent baskets interconnected
along the top and vertical edges using permanent fasteners. Where lacing wire is used, wire
shall be wrapped with alternating single and double loops every-other mesh opening, and
not more than 150 mm apart. Where spiral binders are used, ends shall be crimped to secure
the binders in place. Where alternate fasteners are used, they shall be spaced in every mesh
opening and not more than 150 mm apart.

Each row or tier of baskets shall be reasonably straight and shall conform to alignment and
grade. Hexagonal mesh baskets shall be stretched endwise before filling. Each basket shall
be filled completely so that the secured lid rests upon layer of stones. Each basket shall be
laced securely to all adjacent baskets and its lid then laced or clipped to the sides, ends, and
diaphragms, in the manner described above.

Gabion cage corners shall be securely wired together to provide a uniform surface and
ensure that the surface does not resemble a series of blocks or panels.

All selvage wires at the end of adjacent baskets shall be laced together. Bottom selvage of
the basket being constructed on a previously constructed basket shall be laced to the top of
that basket. Empty gabions stacked on filled gabions shall be laced to the filled gabion at the

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front, side, and back. Vertical joints between baskets of adjacent rows and layers shall be
staggered by at least one cell length.

After filling the baskets, the Contractor shall secure the lids to the sides, ends, and
diaphragms in the manner described above. All exposed basket surfaces shall be smooth
and neat with no sharp rock edges projecting through the wire mesh.

Backfilling behind or around gabions shall conform to Section 2.5 of Chapter 2, Earthworks,
using an acceptable, lightweight mechanical or vibratory compactor within 1-m of the gabion
baskets. Fine grained soil backfill shall be separated from the stone filled baskets by a layer
of geotextile fabric and aggregate material meeting the requirements of Table 2-4 of Chapter
2, Earthworks, unless otherwise shown on the Contract plans or approved by the Engineer.

All necessary bolts, nuts, and hardware shall be supplied by the Contractor for complete
assembly of the units into a continuous wall of connected units. Gabion walls shall be erected
according to the fabricator's or manufacturer's instructions. On curves, the proper curvature
for the face shall be obtained by using shorter stringers in the front or rear panels. Walls shall
be constructed to within ±25 mm from the lines and elevations shown on the Contract plans.

6. Gabion Mattress Erection

Gabions forming aprons and revetments shall be filled by random stones packed in the first
layer and selected stones used for the top layer, so as to resemble normal stone riprap. Least
dimension of stones for gabion mattress applications shall be as shown on the Contract
plans, typically 75 mm to 300 mm.

7.4 Slope Protection

This  work  shall  consist  of  preparing  the  foundation  and  applying  materials  to  protect  a  slope  in
accordance  with  the  Contract  plans,  Particular  Specifications  and  requirements  of  these
Specifications, as approved by the Engineer. Work shall conform with the locations, lines, grades,
and dimensions as shown on the Contract plans or as staked by the Engineer or any other innovative
but  economical  solution  not  mentioned  herein  but  approved  by  the  Engineer  and  the  DoT/
Mnucipalities at no extra cost to client. Various approaches to slope protection are discussed herein
and as follows:

•

Slope paving, Section 7.4.1

•

Wire mesh slope protection, Section 7.4.2

•

Riprap slope protection, Section 7.4.3

•

Coarse aggregate covering, Section 7.4.4

7.4.1 Slope Paving

7.4.1.1

Description

This work consists of covering a graded slope with cast-in-situ-reinforced concrete, brick, precast
concrete blocks, grouted rock, or cellular concrete blocks

7.4.1.2

Materials

Materials shall conform to the requirements of the Contract plans, the Engineer, and these
Specifications, including those sections specifically noted in Table 7-22. Other materials required
shall be as specified in the particular specifications.

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Table 7-22: Materials for concrete slope paving

Material

Specifications Requirements

Bedding course

Gradation

Liquid limit

AASHTO T 27, AASHTO T 11

AASHTO T 89

Concrete and its constituent materials

Section 4.3 of Chapter 4, Concrete
Works

Grout

Article 4.3.10.4 of Chapter 4,
Concrete Works

Shotcrete for slope paving

Cement, water, aggregate;

Wire mesh reinforcement

Article 4.3.10.5 of Chapter 4,
Concrete Works

Section 4.3 of Chapter 4, Concrete
Works

Section 7.4.2

Concrete masonry blocks, precast concrete blocks,
brick, cellular concrete blocks, mortar

Section 6.2.2 of Chapter 6, Masonry

Rock* and mortar for rock masonry

Section 6.3.2 of Chapter 6, Masonry

Geotextile for separation or soil stabilization

Article

2.5.2.9

Chapter

Earthworks

Topsoil

Article

2.2.2.5

Chapter

Earthworks

*Rock for slope paving shall conform to the requirements of Article 6.3.2.1 of Chapter 6,
Masonry, unless otherwise shown on the Contract plans or directed of the Engineer.

7.4.1.3

Construction Requirements

a. Footing and Preparation of Slope

Surfaces requiring slope protection shall be thoroughly compacted and neatly trimmed to conform to
the line, grade, and detail in the Contract plans. Minimum required compaction for slopes where
bedding course is installed shall be 3 passes of a lightweight mechanical tamper, roller, or vibratory
system.

Excavation and backfill for the slope foundation shall be constructed in accordance with Article
2.4.2.11of Chapter 2, Earthworks. Footings, if required, shall be unreinforced concrete, as shown in
the Contract plans. No curing or strength testing of the footing concrete is required, and a wood float
finish is acceptable. Footing costs shall be incidental to the slope protection with no separate
measurement or payment.

When required, geotextile shall be placed per Section 2.7 of Chapter 2, Earthworks. Ends of the
geotextile shall be buried for anchorage. Strips shall be pinned at 1.5 m intervals to hold the
geotextile lap in place until concrete is placed. Any torn or punctured geotextile shall be repaired or
replaced in accordance with Section 2.7.3 of Chapter 2, Earthworks.

b. Installing Brick, Precast Concrete Blocks, and Grouted Rock

Brick, precast concrete blocks, or rock shall be placed in the following manner:

•

In a uniform plane

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•

Starting at the bottom of the slope

•

Such that they rest firmly and evenly against the slope with no rocking

•

In horizontal parallel courses with the longest dimension placed parallel to the bottom of the

slope and flat faces along the plane of the finished slope protection

•

Such that joints in successive courses do not align with joints in the preceding course

After each brick or block is placed, mortar shall be applied on the exposed sides in such quantities
that when the adjacent brick or block is placed and rammed into position, the mortar is within 13 mm
of the surface and not protruding above the top.

Brick and masonry block joints shall be 13 mm wide, or less. Grouted rock joints shall be 25 mm
wide, or less. All mortar stain shall be cleaned from the surface.

For grouted rock installation, rocks shall be placed as described above, and then grouted in sections.
A heavy flat steel sheet dropped from a height of 2 m may be used to flatten and level the rock
surface after placement of the rock and prior to grouting.

c. Architectural Grouted Rock Placement

Work shall be performed as described in Sub-article b, of Article 7.4.1.3, with the following additional
requirements:

1. Rock shall conform to one of the classes of masonry work defined in Section 6.3.3 of Chapter

6, Masonry

2. Grout shall be Class G6, meeting the requirements of Article 4.3.10.4 of Chapter 4, Concrete

Works

Rock shall be installed by masons experienced in the work. Documentation of each mason’s
experience shall be provided by the Contractor upon request of the Engineer

4. Rock shall be selected for appearance; colour; grain pattern; and smooth, large, flat surfaces

to be placed on top. Rock selection shall be in accordance with the Contract plans and the
direction of the Engineer

5. Rock shall be placed on a mortar bed conforming to the thickness requirements in Section

6.3.3 of Chapter 6, Masonry. Unless otherwise shown on the Contract plans, mortar shall meet
the requirements of Section 6.3.2 of Chapter 6, Masonry, and may be preblended or mixed on-
site. Mortar beds shall not lay longer than 45 minutes or until mortar begins to set before placing
rock.

6. Freshly placed rock shall be damp cured for at least 72 hours prior to grouting.

7. Pointing and grouting material shall be the same as for the mortar bed.

8. Test sections shall be prepared for approval of the Engineer regarding colour, shape,

smoothness, technique, and overall aesthetic. Test sections shall be required for each set of
different sizes or colours or patterns, as required on the Contract plans or the Particular
Specifications.

9. Test sections shall be either of the following:

•

Placed on the worksite. In this case, acceptable test sections may be incorporated into the

works after approval by the Engineer, and unacceptable test sections shall be removed and
replaced until the test section is approved by the Engineer

•

Placed on test panels measuring at least 3 m on a side. Backings shall be either plywood

or existing ground at a location outside the worksite. In this case, test sections shall be
removed and redone, if unacceptable

10. Acceptable test sections shall be preserved and protected from damage, including sunlight,

until all permanent installations have received the Engineer

’s approval

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d. Placing Cellular Concrete Blocks

Cellular concrete blocks shall be placed according to the Contract plans, starting in a trench or
against a suitable anchorage at the bottom of the slope. Each block shall be laid perpendicular to
the slope and bed firmly against adjoining blocks. Misaligned joints or breaks at slope changes shall
be filled with grout. Individual blocks shall not be grouted to each other.

Topsoil shall be spread loosely over the cellular block slope paving, partially filling the cell openings.
If required, turf establishment shall be performed as shown on the Contract plans.

e. Cast-in-situ Reinforced Concrete

Prior to concrete placement, surfaces shall be damp, but application shall not be made on any
surface on which freestanding water exists.

Wire mesh reinforcement shall be placed continuously through joints with minimum laps of one mesh
spacing, or 150 mm, whichever is greater. Laps shall be securely fastened at the ends. During the
placement of the concrete, the reinforcement shall be secured so as to provide at least 30 mm of
cover.

Concrete placement shall begin at the bottom of the slope. Methods for depositing and compacting
concrete shall result in a compact, dense, and impervious concrete with a uniform plane surface.
Horizontal joints shall be parallel to the bottom of the slope. Vertical joints shall be perpendicular to
the horizontal joints. Cold joints shall not require filler.

Newly constructed concrete shall be finished per Article 7.6.4.4 with additional details as shown in
the Contract plans. Outside edges of the slab and all joints shall be finished with a 6 mm radius
edging tool.

Curing shall be performed in accordance with Article 3.8.3.8 of Chapter 3, Pavement.

Additional requirements for poured concrete slope protection shall be as follows:

•

Concrete shall be the class shown in the Contract plans, or Class C15/20, in conformance with

Chapter 4, Concrete Works.

•

Toe walls shall be constructed as necessary or indicated on the Contract plans or at the

direction of the Engineer.

For shotcrete slope protection, the Contractor shall comply with the requirements of Section 7.3.3.

7.4.2 Wire Mesh Slope Protection

7.4.2.1

Description

This work constructs wire mesh slope protection in accordance with these Specifications and the
details, lines and dimensions shown on the Contract plans, as approved by the Engineer.

7.4.2.2

Materials

All metal material used in the construction of wire mesh slope protection shall be new and galvanised.
Imperfectly galvanised material or material upon which serious abrasion of galvanising occurs will
not be acceptable. Materials shall further conform to the requirements of Table 7-23 and Table 7-24.

Wire mesh for slope protection shall be either diamond chain-link or hexagonal double-twisted,
conforming to the respective requirements of Table 7-23. Wire shall be galvanised prior to weaving
and mesh shall be of nonraveling construction. Edges shall be selvedged so as to prevent unraveling
and develop the full strength of the mesh.

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Table 7-23: Material requirements for wire mesh reinforcement

Property

Requirements for

Diamond Chain-Link

Requirements for Hexagonal Double-

Twisted

Meeting the requirements
of:

AASHTO M 181

ASTM A641M, Class 3, finish 5, soft
temper

Steel wire diameter

3.8 mm

3.0 mm**

Galvanizing*

ASTM A392, zinc
coating shall be ≥250
g/m

uncoated wire

surface

Zinc coating ASTM A641M tested in
accordance with ASTM A370.
High grade or special high grade in
accordance with ASTM B6, Table 1.
Weight determined by ASTM A90.

Size of opening in mesh

90 mm by 140 mm

85 mm by 115 mm, about 60 cm

Selvedges

Nominal diameter

Knuckled

3.9 mm

Lacing wire

Diameter

N/A

Same type as for mesh

2.2 mm**

Minimum tensile strength
per ASTM A370

N/A

415 MPa

*Galvanizing shall be done before weaving.

**After galvanising.

Acceptance of all materials shall be based on certificates of compliance submitted to the Engineer
for approval.

Table 7-24: Material requirements for wire mesh slope protection components

Material

Requirement

Wire Rope

Material

Diameter

Standard

Zinc-coated steel structural wire rope

15.9 mm

ASTM A603, Class A, ASTM A475

Hardware

Rings

Lightweight wire rope thimbles

Wire rope clips

Galvanizing

Rings, thimbles, wire rope clips, U-
bolts

Castings

Forgings

Drop-forged steel, heat treated after forging

Approximately 6.3 kg per 100

Drop-forged steel or cast steel

AASHTO M 232M, Class C

AASHTO M 232M, Class A

AASHTO M 232M, Class B

Hog rings and tie wire

Manufactured from 2.9 mm of steel wire meeting
Federal Specification QQ-W-461H, AISI numbers

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Material

Requirement

1010 and 1015, finish five; of medium hardness and
tensile strength; Class 3 coating

Grout for anchors

Class G3, per Article 4.3.10.4 of Chapter 4, Concrete
Works

Anchor rods

Material

Eye construction

Galvanization

ASTM A36M

Drop-forged or formed with a full-penetration weld
and shall develop 100 % of rod strength

ASTM A153M

7.4.2.3

Construction Requirements

a. Anchors

Contractor shall install anchors of the type shown in conformance to the layout shown in the Contract
plans. Spacings and numbers of the anchors and wire ropes, as shown in the Contract plans, are
approximate only, and the Engineer will give the Contractor the required spacing to hold the wire
mesh against the slope. Backfill material shall be thoroughly compacted.

b. Wire Rope Assembly

Wire rope assembly shall be in place before the wire mesh is attached. Bottom wire rope shall not
be tensioned. No wire rope splicing will be allowed.

c. Wire Mesh

Wire mesh shall be fastened to the completed wire rope assembly as shown in the Contract plans.

Hog rings on the vertical lap splices shall be placed in a single row centred on the splice.

Horizontal splices joining 2 rolls of mesh shall be made by removing a horizontal end wire and
reweaving through the ends of the fabric to form a continuous mesh.

All top and bottom laps shall be made by folding the mesh to the outside, away from the slope, to
avoid the possibility of falling material hanging up in the folds.

Bottom of the mesh shall be located so that material dislodged under the mesh can drain freely from
the bottom, yet will not flow or bounce onto the roadway. Ends of all tie wires shall be secured to the
mesh with a minimum of 1.5 turns.

Wire mesh shall not be tensioned in any direction, but is to remain loose so as to increase its
dampening effect on rolling rocks. Any mesh or wire rope damaged due to the Contractor

’s

operations shall be replaced by the Contractor at no expense to the Owner.

7.4.3 Riprap Slope Protection

7.4.3.1

Description

This work furnishes and places riprap for slope protection, as shown on the Contract plans. Riprap
shall consist of broken stone, broken concrete rubble, or concrete in sacks. Riprap classes shall be
as defined herein.

7.4.3.2

Material

Riprap rock shall be hard, durable, angular rock that is resistant to weathering and water action and
free of organic or other unsuitable material as approved by the Engineer. Shale, rock with shale
seams, or other fissile or fissured rock that may break into smaller pieces in the process of handling

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and placing shall not be used. Riprap rock shall conform to the gradations in Table 7-25. Grading of
the riprap shall be determined by the Engineer by visual inspection of the load before it is dumped
into place; or, if so ordered by the Engineer, by dumping individual loads on a flat surface and sorting
and measuring the individual rocks contained in the load.

Table 7-25: Classes of riprap, defined by gradation

Percent of Rock by Mass

20 %

30 %

40 %

10 %*

Class 1

Mass (kg)

[Size (mm)**]

10 to 15

[150 to 200]

5 to 10

[125 to 150]

0.5 to 5

[50 125]

0 to 0.5

[0 to 50]

Class 2

Mass (kg)

[Size (mm)**]

25 to 50

[200 to 250]

10 to 25

[150 to 200]

1 to 10

[75 to 150]

0 to 1

[0 to 75]

Class 3

Mass (kg)

[Size (mm)**]

100 to 150

[350 to 400]

50 to 100

[250 to 350]

5 to 50

[125 to 250]

0 to 5

[0 to 125]

Class 4

Mass (kg)

[Size (mm)**]

250 to 350

[450 to 500]

100 to 250

[350 to 450]

10 to 100

[150 to 350]

0 to 10

[0 to 150]

Class 5

Mass (kg)

[Size (mm)**]

700 to 1,000

[650 to 700]

350 to 700

[500 to 650]

25 to 350

[200 to 500]

0 to 25

[0 to 200]

Class 6

Mass (kg)

[Size (mm)**]

850 to 1,600

[700 to 850]

500 to 850

[550 to 700]

50 to 500

[250 to 550]

0 to 50

[0 to 250]

*Spalls and rock fragments graded to provide a stable dense mass shall be furnished by the Contractor.

**Approximate cubic dimension. Volume of a rock with these cubic dimensions has a mass approximately
equal to the mass specified. Rock with breadth and thickness at least one-third its length shall be furnished.

Quarry spalls shall consist of broken stone or broken concrete rubble. Riprap and quarry spalls
consisting of broken stone or concrete rubble shall be free from segregation, seams, cracks, and
other defects tending to destroy its resistance to weather and shall conform to Table 7-26.

Table 7-26: Quality requirements for riprap and quarry spalls

Aggregate property

Test Method

Requirement

Los Angeles wear, 500

Rev.

AASHTO T 96

50 % maximum

Specific gravity

AASHTO T 85

2.55 minimum

Absorption

AASHTO T 85

4.2 % maximum

Coarse durability index

AASHTO T 210

50 minimum

Should the riprap contain insufficient spalls, the Contractor shall furnish and place supplementary
spall material from a source approved by the Engineer, at the Contractor

’s expense.

Grout shall meet the requirements set out in Article 4.3.10.4 of Chapter 4, Concrete Works, and grout
and shall be of the class specified in the Contract plans.

a. Hand-placed Riprap

Hand-placed riprap shall be as nearly rectangular as possible, and 60 % of the stones shall have a
cubic dimension of not less than 300 mm. No stone shall be used that is less than 150 mm thick.

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b. Sack Riprap

Sack riprap shall consist of concrete placed in sacks made of at least AASHTO M 182, Class 3
burlap, having a capacity of approximately 0.05 m

. Each sack shall be filled with concrete.

Concrete for sack riprap exposed to fresh water and salt water shall be Class C20. Aggregate
gradation for sack riprap shall conform to the following, or as approved by the Engineer:

•

100 % passing the 50-mm sieve

•

45 % to 89 % passing the 6-mm sieve

•

0 % to 12 % passing the 0.075-mm sieve

c. Quarry Spalls

Quarry spalls shall meet the requirements for grading in Table 7-27.

Table 7-27: Quarry spalls gradation

Sieve Size

Percent Passing

200 mm

100 %

75 mm

≤40 %

18 mm

≤10 %

7.4.3.3

Construction Requirements

a. Excavation and Preparation for Riprap

Foundations for riprap shall be excavated below probable scour, or to the elevation shown in the
Contract plans, and no rock shall be laid nor concrete placed until the footing is approved by the
Engineer.

Excavation below the level of the intersection of the slope to be protected and the adjacent original
ground or the channel floor or slope shall meet the requirements for ditch excavation in accordance
with Article 2.4.2.9 of Chapter 2, Earthworks. All excavation or backfill above the level of the
intersection described above and all dressing of the slope to be protected shall be included in the
Contract price for the class of riprap to be placed. Before placing riprap, the slopes shall be dressed
to the lines and grades as staked.

Where required, geotextile fabric shall be placed loosely, not stretched, prior to riprap placement as
shown on the Contract plans and in accordance with Section 2.7 of Chapter 2, Earthworks. Strips of
fabric shall overlap at least 600 mm at each joint. On horizontal joints, the uphill strip shall overlap
the downhill strip. On vertical joints, the upstream strip shall overlap the downstream strip.

Geosynthetic fabric shall be protected at all times during construction from exposure to sunlight, and
total exposure shall not exceed 14 calendar days.

When  the maximum  size  of  the rock  to  be  placed  on  fabric  exceeds  450  mm,  the  fabric  shall  be
protected during the placement of the rock by a layer of bedding material spread uniformly on the
fabric to a minimum depth of 150 mm. Compaction of the bedding shall not be required. Rocks shall
be placed carefully on the bedding material and fabric in such a manner as not to damage the fabric.
If,  in  the  opinion  of  the  Engineer,  the  fabric  is  damaged  or  displaced  to  the  extent  that  it  cannot
function  as  intended,  the  Contractor  shall  remove  the  rock;  regrade  the  area,  if  necessary;  and
replace the fabric at no additional expense to the Owner.

b. Loose Riprap

Loose riprap shall be placed in such a manner that all relatively large stones are essentially in contact
with each other, and all voids filled with the finer materials to provide a well graded compact mass.

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Stone shall be dumped on the slope in a manner that will ensure the riprap attains its specified
thickness in one operation. When dumping or placing, the Contractor shall use care to avoid
disturbing the underlying material.

Placing in layers parallel to the slope will not be permitted. A 300-mm tolerance for loose riprap will
be allowed from slope plane and grade line in the finished surface. Hand placing or rearranging of
individual rock may be necessary to obtain the specified results.

c. Hand-placed Riprap

Stones shall be laid by hand on prepared slopes to such thickness as may be ordered by the
Engineer. Riprap shall be started at the toe of the embankment by digging a trench and placing a
course of the largest stones therein. Each stone shall be placed so that it rests on the slope of the
embankment and not wholly on the stone below, and it shall be thoroughly tamped or driven into
place. Exposed face of all hand-placed riprap shall be made as smooth as the shape and size of the
stones will permit and shall not vary more than 75 mm from a plane surface on the required slope.

d. Keyed Riprap

Keyed riprap, also called plated riprap, is rock placed on a prepared surface and set into place by
impact pressure to seat the rocks together and form a relative flat and uniform rock surface. Rock
shall first be placed per Sub-article b, of Article 7.4.3.3. Then, the riprap is set into place by exerting
impact pressure with a hydraulic-powered bucket or an approximate 2,000 kg flat-faced mass.
Impact shall be repeated until the rock is firmly seated and forms a reasonably uniform surface
without reducing the effective sizes of the rocks. Levelling or plating process shall not be to an impact
force that breaks the rock.

e. Sack Riprap

Sack riprap shall be deposited in the trench and on the slope of the embankment to be protected in
accordance with the Contract plans or as ordered by the Engineer. Concrete shall be placed in the
sacks to a uniform volume leaving sufficient room for effectively tying the sacks.

Sacks shall then be placed in longitudinal rows in the trench and on the slope to lie parallel with the
slope. In placing the sacks on the slope, their outside faces shall be laid against a heavy timber
header or screed so that each layer will be true to the line and grade. Tied ends of the sack shall be
turned under and the sack firmly pressed into place against the header or screed.

Sacks in longitudinal rows shall be placed with the bottom of one sack adjacent to the top of the next
sack. Joints shall be staggered in successive rows.

f. Quarry Spalls

Quarry spalls shall be placed in ditches and on slopes to be protected, in accordance with the
Contract plans or as directed by the Engineer. After placement, the quarry spalls shall be compacted
to be uniformly dense and unyielding.

g. Filter Blanket

When required, a filter blanket shall be placed on the prepared slope or area to the full thickness
shown on the Contract plans using methods that will not cause segregation of particle sizes within
the bedding. Surfaces of the finished layer shall be even and free from mounds or windrows.
Additional layers of filter material, when required, shall be placed using methods that will not cause
mixing of the materials in the different layers.

h. Grouted Riprap

Grouted riprap is rock placed or keyed on a prepared surface with the voids filled with grout. Rock
shall first be placed in accordance with Sub-articles b or d, of Article 7.4.3.3. Then, the Contractor
shall thoroughly moisten the rocks and wash excess fines from the riprap or to the underside of the

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riprap. Grout shall be placed to prevent segregation, beginning at the lowest elevation of the riprap.
All voids shall be filled without unseating the rocks.

Grout may be delivered to the place of final deposit by any means that will ensure uniformity and
prevent segregation of the grout. If penetration of grout is not obtained by gravity flow into the
interstices, the grout shall be spaded or rodded to completely fill the voids in the rock blanket.
Pressure grouting shall not unseat the stones, and during placing by this method, the grout shall be
spaded or rodded into the voids.

Penetration of the grout shall be to the depth shown on the Contract plans. When a rough surface is
specified, stone shall be brushed until 25 % to 50 % of the depth of the maximum size stone is
exposed. For a smooth surface, grout shall fill interstices to within 13 mm of the surface.

Curing of the grout shall be in accordance with the requirements of Sub-article f, of Article 7.3.3.3 .
At the option of the Contractor, shotcrete conforming to the requirements of Article 4.3.10.5 of
Chapter 4, Concrete Works, may be furnished in lieu of grout.

Each layer of grouted riprap shall be 1.5 m or less in thickness. Contractor shall allow 3 days curing
time before adding the next layer of riprap and grout. Weep holes shall be provided through the
grouted riprap, as required by the Contract plans or the Engineer. Grouted riprap shall be cured by
placing wet blankets to keep it moist for 3 days after the work is completed.

7.4.4 Coarse Aggregate Covering

This work consists of a layer of coarse aggregate placed to a uniform depth to the limits and for the
depth shown on the Contract plans as approved by the Engineer.

Selection of aggregate sizes and colour requirements

— or other required architectural attributes —

shall be as shown in the Contract plans or as directed by the Engineer. Unless otherwise indicated,
coarse  aggregate  shall  be  size  4  coarse  aggregate  as  defined  in  Article  4.3.7.3  of  Chapter  4,
Concrete Works. Course aggregate used for surface covering shall be approved by the  Engineer
prior to installation.

Areas on which the coarse aggregate covering is to be placed shall be shaped to a reasonably true
surface prior to placement. Coarse gravel shall be spread by any suitable means that shall not crush
it and shall be shaped to a smooth uniform finished grade.

7.5 Concrete Kerbs, Gutters, Parapets, and Barriers

7.5.1 Description

This work constructs reinforced concrete kerb, kerb and gutter, gutter, parapet, median barrier, and
side  barrier  to  the  type,  dimensions,  and  details  shown  in  the  Contract  plans  or  directed  by  the
Engineer.  This  work  includes  both  temporary  and  permanent  applications.  Barrier,  parapet,  kerb,
and gutter may be on grade or structures. Construction shall conform to the details, lines and grades
shown  on the  Contract plans,  as  required  in these  Specifications,  and  as  may  be  required  in the
Particular Specifications, as approved by the Engineer.  Construction methods shall be one of the
following:

•

Cast-in-situ fixed-form

•

Cast-in-situ slip-form

•

Precast

This work may also include the removal, storage, and resetting of temporary barrier at the locations
shown on the Contract plans or as approved by the Engineer.

7.5.2 Materials

Unless otherwise specified in the Contract plans or by the Engineer, materials shall conform to the
requirements of Table 7-28.

ONSTRUCTION

Table 7-28: Material requirements for concrete barriers, parapets, kerbs, and gutters

Material

Requirement Specifications

Concrete and its constituent materials;
premolded joint filler; joint sealer; water-
reducing admixture
Reinforcing steel

Section 4.3 of Chapter 4, Concrete Works

Chapter 5, Reinforcing Steel

Paint formulas

Articles 8.2.2.7 or 8.2.2.8 of Chapter 8, Traffic
Markings and Signs.

Water-repellent compound

Table 24-13 of Chapter 24, Painting

Wire rope

Material
Galvanization
Weave
Minimum diameter
Minimum breaking strength

Class 6 x 19
Improved plow steel
ASTM A603
Right regular lay and fibre core
16 mm
13.6 metric tons

Anchor bolts

Nuts for anchor bolts
Lubrication
Washers for anchor bolts

ASTM F1554 and S2, S3, and S4*; Grade 105
AASHTO M 291M, Grade DH
AASHTO M 291M, and S2(*)(**)
ASTM F436

Unfinished bolts

Nuts for unfinished bolts

Washers for unfinished bolts

ASTM A307 Grade A or B

ASTM A563 Grade A

ASTM F844

Grout for permanent precast barrier

Meet the requirements for grout for ground anchors,
Article 4.3.10.4 of Chapter 4, Concrete Works

*Supplemental requirements are designated with an S prefix.
**Documentation shall include the name, method of application, and dilution of the lubricant
applied to the nuts.

All hardware shall be galvanised per AASHTO M 232M, tested by the manufacturer, marked or
identified per the relevant specification, and inspected prior to shipping to the site of the works.

A manufacturer’s certificate of compliance that demonstrates conformance to these specifications
and the applicable standards referenced herein shall be submitted by the Contractor to the Engineer
for approval. A sample of the anchor bolt, nut, and washer shall be provided by the Contractor for
testing, if requested by the Engineer.

Minimum concrete strengths for various applications shall be as described in Table 7-29.

Table 7-29: Minimum required concrete strengths for kerb, gutter, parapet, and barrier

Application

Minimum Concrete Requirements

Cast-in-situ kerb, kerb and gutter, gutter not at driveway
entrances

Class C20

Cast-in-situ kerb, kerb and gutter, gutter along driveway
entrances

Class C30

Precast kerb, parapet, and barrier

Class C30

All barriers and parapets

Class C30

Pavement, cap, or slab between concrete barriers

Class C15

ONSTRUCTION

For precast kerb, cement content shall be at least 400 kg/m

, and the aggregate gradation shall meet

the requirements for nominal maximum size 19 mm aggregate as shown in Article 4.3.7.4 of Chapter
4, Concrete Works.

7.5.3 Construction Requirements

Unless otherwise indicated on the Contract plans or specified in the Particular Specifications, kerbs,
gutters, kerb and gutter, parapets, and barriers shall conform to the following:

•

Constructed in straight line segments

•

Cast-in-situ, if located on superstructures or approach slabs, and constructed after the deck is

complete and all post-tensioning has been accomplished

•

Cast-in-situ using fixed forms if installed in conjunction with light standard foundations and sign

bridge foundations

Maximum allowable deviation from a 3 m straightedge held longitudinally on all surfaces shall be 6
mm. For single sloped barrier the maximum allowable deviation from a straightedge held along the
vertical sloped face of the barrier shall be 6 mm.

Segments of cast-in-situ barrier, parapet or kerb may be joined to precast barrier, parapet or kerb
where transitions, split barriers or gaps shorter than 3 m require it. At each joint of this type, the cast-
in-situ segment shall include hardware that ties both its ends to abutting precast sections.

7.5.3.1

Preparation of the Foundation

Foundations for kerb, gutter, kerb and gutter, parapet, and barrier shall be either prepared subgrade
or pavement. Subgrade shall be firm, unyielding material that consists of the following:

•

Shaped to the line, grade, and cross section shown in the Contract plans

•

Thoroughly compacted

•

Watered thoroughly, leaving no standing water just before concrete is placed

Prepared subgrade surfaces shall be proof-rolled to check for unstable areas and areas requiring
additional compaction. Unsuitable material shall be removed per Article 2.4.2.7 of Chapter 2,
Earthworks. Any excavated surfaces for the concrete bedding shall be watered and compacted to a
minimum of 95 % maximum density.

Clamps, spreaders, and braces shall be used where required to insure rigid forms. When the
roadway section slopes away from the gutter, the slope of the gutter shall be formed to match the
roadway cross slope.

All old pavements and any portion of new pavements constructed under this Contract, which are
covered with oil or grease within the kerb limits, shall be further cleaned as follows:

1. Pavement shall be flushed with water

2. Where patches of oil, tar, or grease occur, these areas shall be scrubbed with a solvent-type

cleaner and brush or broom

3. Pavement surfaces shall then be thoroughly rinsed

7.5.3.2

Kerb Painting

Kerb painting shall be accomplished in accordance with Sub-articles 8.2.3.3b, 8.2.3.3e and 8.2.3.3h
of Chapter 8, Traffic marking and Signs. Kerbs along main roads, sector roads, and parking areas
shall be painted as shown on the Contract plans. Lengths for each band shall be 1.20 m. Paint shall
be on the exposed kerb surfaces after kerb and pavement are in place or as directed by the Engineer.

All kerb paint shall be applied to a minimum dry film thickness of 150 microns (in 2 coats) and achieve
a minimum tensile adhesion of 2.0 MPa.

ONSTRUCTION

In accordance with the TCDM, kerb painting treatment in Abu Dhabi denotes parking classifications
and restrictions. The colours used indicate the following:

•

Kerbs painted grey

- standard kerb

-new kerbing is not to be painted

•

Kerbs painted blue and black

-standard parking charges apply

•

Kerbs painted blue and white

-premium parking charges apply

•

Kerbs painted yellow and grey

-parking prohibited

-to be applied at sectors where paid parking is operated

•

Kerbs painted yellow

-visibility marking (junctions, entry/exits, intersections,

roundabouts, and traffic separation islands)

•

Kerbs painted red

-parking prohibited (adjacent to fire hydrants)

•

Kerbs painted blue

-parking for disabled persons

7.5.3.3

Cast-in-situ Fixed-form

a. Formwork

Forms  shall  be  steel  or plywood  that  is  coated with  plastic.  Formwork  and  details,  including  form
liners, shall comply with the requirements of  Section 1.20.8 of  Chapter  1, General Requirements,
and shall be capable of being removed without injuring the green concrete. Forms used more than
once shall be thoroughly cleaned and any forms that have become worn, splintered, or warped shall
not be used again.

Side forms shall rest throughout their length on firm ground. Top of any form or the Contract face of
a straight form shall not vary from a true plane by more than 6 mm in 3 m. Forms for use on curves
shall be capable of installation to within 12 mm of the true curve and if the radius is less than 50 m,
shall be either flexible material or shaped to fit the curve. Forms shall be designed so that they may
be securely fastened together in the correct position.

Formwork shall be properly cleaned and oiled prior to the placement of concrete. Formwork, in
general, shall remain in place for at least 12 hours after concrete placement, except that formwork
shall be removed as required to permit texturing.

Forms  may  be  placed  using  machine  methods,  if  approved  by  the  Engineer,  provided  that  the
Contractor  consistently  produces  an  acceptable  finished  product,  true  to  line,  grade  and  cross
section.

Removal of forms shall be by a method acceptable to the Engineer and shall be performed to avoid
excessive shock and straining of the concrete.

b. Concrete Placement

Concrete placement and vibration shall conform to the requirements of Section 4.4.1 of Chapter 4,
Concrete Works.

Small amounts of consolidated concrete totalling not more than 0.06 m

in volume, and spaced at

least 3 m apart, may be used to support reinforcing steel within barrier forms, and they shall provide
50 mm minimum clearance to the outside face of the barrier.

Edge chamfers shall be formed by attaching chamfer strips to the forms.

c. Expansion and Dummy Joints

Expansion joints shall be placed as shown on the Contract plans and at the following locations:

1. Beginning and ends of kerb returns

ONSTRUCTION

2. Kerb abutting drainage structures

3. Kerb abutting bridges

4. Radius points

5. Cold joints with existing kerbs and gutters

6. Every 4.5 m or less for kerb, gutter, and kerb and gutter

7. Every 30 m for barriers with dummy joints every 3 m

Expansion joints shall cover the full cross section with 10 mm premoulded joint filler, except between
kerb or gutter and cement concrete pavement. Expansion joints shall be a 6 mm-thick, 150 mm deep
premoulded joint filler placed between the surfaces to prevent cracking.

Contraction joints shall be placed every 3 m, except where closure requires a lesser interval, but
they shall not be closer than 1.2 m. They may be formed with forms or by sawing or by using sheet
metal templates, with the following requirements:

1. Sheet metal templates:

•

Shall be of the dimensions, and set to the lines, shown in the Contract plans

•

Shall hold firmly during concrete placement

•

Shall remain in place until the concrete has set sufficient to hold its shape

•

Shall be removed while the forms are still in place

2. Sawn joints shall be completed:

•

As soon as the concrete has hardened to the degree that excessive ravelling will not occur

•

Before shrinkage cracking begins

d. Curing and Finishing

Curing for barriers shall conform to Method A, supplying continuous moisture, per Article 4.4.2.1 of
Chapter 4, Concrete Works, and the additional requirements or exceptions of this section. Membrane
curing compound shall not be used on barriers.

Kerb, gutter, and kerb and gutter shall be cured for at least 72 hours by one of the methods specified
for cement concrete pavement curing in Article 3.8.3.8 of Chapter 3, Pavement.

Exposed kerb and gutter surfaces shall be finished with a trowel and edger. Within 24 hours after
concrete placement, forms on the roadway face of kerbs shall be removed, and the concrete treated
with a float finish. Tops and faces of the kerbs shall receive a light brush finish, and the top of the
gutters shall receive a broom finish. Minor defects shall be filled with Class M6 mortar per Article
4.3.10.4 of Chapter 4, Concrete Works. Plastering shall not be allowed on the face of the kerb.

To finish cast-in-situ, fixed-form barriers, the Contractor shall complete the following procedure:

While the forms are in place, the Contractor shall:

1. Brush the top surface with a fine bristle brush

2. Cover the top surface with heavy, quilted blankets

3. Spray water on the blankets and forms at intervals short enough to keep them thoroughly wet

for 72 hours

After removing the forms, the Contractor shall:

1. Remove all lips and edgings with sharp tools or chisels

2. Fill all holes with mortar

3. True up corners of openings

ONSTRUCTION

4. Remove concrete projecting beyond the true surface by stoning or grinding

After removing the forms, the Contractor shall cover the barrier with heavy, quilted blankets, not
burlap, and keep the blankets continuously wet for at least 7 days. During this time, the Contractor
may perform the required finishing work if the entire structure is kept covered and wet except the
immediate work area. Otherwise, no finishing work may be done until at least 10 days after pouring.

After the 10-day curing period, the Contractor shall remove all form-release agent, mud, dust, and
other foreign substances from the structure by either light sandblasting and washing with water, or
by spraying with a high-pressure water jet. Water jet equipment shall use clean fresh water and shall
produce at least 105 kg/cm

at the nozzle with a discharge of at least 11 litres per minute. Water jet

nozzles shall have a 25-degree tip and shall be held no more than 230 mm from the surface being
washed.

After cleaning, the Contractor shall use brushes to rub Class M6 mortar into air holes and small
crevices on all surfaces, except the brushed top. As soon as the mortar takes its initial set, the
Contractor shall rub it off with a piece of sacking or carpet. Structure shall then be covered with wet
blankets for at least 48 hours.

Completed concrete surfaces shall be even in colour and texture with a uniformly smooth, dense
surface, no rock pockets, and no holes larger than 6 mm across.

7.5.3.4

Cast-in-situ, Slip-formed Kerb, Parapet, and Barrier

Slip-formed, also called extruded, cement concrete kerb, gutter, kerb and gutter, parapet, and barrier
shall conform to the applicable requirements of Chapter 4, Concrete Works, for materials, placement
and testing. Slip-formed work shall be placed, shaped, and compacted to the required line and grade
as shown in the Contract plans or as directed by the Engineer with approved equipment. When
placing of concrete is suspended for more than 45 minutes, a construction joint shall be formed and
its location shall not be at a Contraction joint.

A trial slip form placement for each type of kerb, parapet, or barrier shall be performed for acceptance
by the Engineer to demonstrate the adequacy of the slip-form equipment and the Contractor

’s

operation. Trial sections may be included as part of the finished work and left in place if accepted by
the Engineer. Otherwise trial sections shall be broken up, removed, and disposed of, as approved
by the Engineer.

Slip-form equipment shall be approved by the Engineer prior to use and shall consist of the following:

a. Self-propelled

b. Capable of shaping and thoroughly compacting concrete to the required cross section

c. Easily adjustable vertically during the forward motion of the machine to provide variable heights

necessary to conform to the required grade

d. Capable of continually comparing the slip-form work to the grade guideline by way of a pointer

or gauge attached to the machine

If required by the Engineer, the Contractor shall demonstrate that the specific slip-form equipment
proposed for use can satisfactorily place the concrete mix. If, at any time, the placement results are
not satisfactory to the Engineer, the use of the slip-form equipment shall be discontinued. Additional
equipment and small tools necessary for completing the work shall be provided by the Contractor.
Supply of concrete to the machine shall be sufficient for uninterrupted placement to the full width and
depth of the mould on the slip-form machine.

A water-reducing admixture may be used in the concrete mix, provided the finished kerb and gutter
retain the required line and shape.

Cement concrete kerb on pavement shall be anchored to the existing pavement by steel tie bars
placed 300 mm on each side of every joint. Tie bars shall meet the dimensions shown in the Contract
plans. Joints in the kerb shall be spaced at 3-m intervals. Joints shall be cut vertically and to the
depth shown in the Contract plans.

Abu Dhabi, United Arab Emirates. STANDARD CONSTRUCTION SPECIFICATIONS (PART 1 - ROADS, Second Edition 2020) - page 46