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

TEEL

Bar

Designation

Nominal Diameter

Nominal Area

Nominal Weight

kg/m

Dia. 10

0.617

Dia. 12

113

0.888

Dia. 14

154

1.21

Dia. 16

201

1.58

Dia. 18

254

2.00

Dia. 20

314

2.47

Dia. 22

380

2.98

Dia. 25

491

3.85

Dia. 28

616

4.83

Dia. 32

804

6.31

Dia. 36

1018

7.99

Dia. 40

1257

9.87

Dia. 45

1590

12.49

Dia. 50

1963

15.4

Table 5-5: Standard wire reinforcement - nominal weights and areas

Wire

designation

Nominal

diameter

Nominal

area

Nominal

weight

kg/m

Area (mm

/m)

Center-to-center spacing, mm

100

150

200

250

300

350

400

MW13

4.0

12.6

0.099

252

168

126

MW16

4.5

15.9

0.125

318

212

159

106

MW20

5.0

19.6

0.154

392

261

196

131

MW24

5.5

23.8

0.187

476

317

238

159

119

MW28

6.0

28.3

0.222

566

377

283

189

142

113

MW33

6.5

33.2

0.260

664

443

332

221

166

133

111

MW38

7.0

38.5

0.302

770

513

385

257

193

154

128

110

TEEL

Wire

designation

Nominal

diameter

Nominal

area

Nominal

weight

kg/m

Area (mm

/m)

Center-to-center spacing, mm

100

150

200

250

300

350

400

MW44

7.5

44.2

0.347

884

589

442

295

221

177

147

126

111

MW50

8.0

50.3

0.396

1006

671

503

335

252

201

168

144

126

MW57

8.5

56.7

0.445

1134

756

567

378

284

227

189

162

142

MW64

9.0

63.6

0.499

1272

848

636

424

318

254

212

182

159

MW71

9.5

70.9

0.556

1418

945

709

473

355

284

236

203

177

MW78

10.0

78.5

0.617

1570

1047

785

523

393

314

262

224

196

MW87

10.5

86.6

0.680

1732

1155

866

577

433

346

289

247

217

MW95

11.0

95.0

0.746

1900

1267

950

633

475

380

317

271

238

MW104

11.5

103.9

0.815

2078

1385

1039

693

520

416

346

297

260

MW113

12.0

113.1

0.888

2262

1508

1131

754

566

452

377

323

283

MASONRY

This work shall consist of furnishing, placing, and constructing concrete blocks, brick masonry, and
rock masonry in accordance with these specifications and conforming to the dimensions shown in
the Contract documents.

6.1

Reference Standards and Codes

Standards and codes for masonry works shall be as specified in these specifications, in the
Contract documents, if any, and the following, in their latest edition:

AASHTO

American Association of State Highway and Transportation Officials - Roadside
Design Guide;

AASHTO

Standard Specifications for Transportation Materials and Methods of Sampling
and Testing;

ASTM

American Society for Testing and Materials;

FHWA

Federal Highway Administration, Eastern Federal Lands Highway Divison, 1996;

BSI

British Standards Institution;

BS EN

European Standards.

Table  6-1  and  Table  6-2  presents  American  Association  of  State  Highway  and  Transportation
Officials  (AASHTO),  American  Society  for  Testing  and  Materials  (ASTM),  British  (BS),  and
European  (BS  EN)  Standards  that  are  related  to  materials  for  masonry  works.  It  also  includes
designations and titles.

Table 6-1: Designations and titles for AASHTO and ASTM standards that apply to masonry

works

AASHTO

DESIGNATION

ASTM

DESIGNATION

TITLE

AASHTO M

114-07

ASTM C62 - 12

Standard Specification for Building Brick (Solid Masonry
Units Made from Clay or Shale).

ASTM C55 - 11

Standard Specification for Concrete Building Brick.

ASTM C90 -

11b

Standard Specification for Loadbearing Concrete Masonry
Units.

ASTM C139 -

Standard Specification for Concrete Masonry Units for
Construction of Catch Basins and Manholes.

ASTM C780 -

Standard

Test

Method

for

Preconstruction

and

Construction Evaluation of Mortars for Plain and
Reinforced Unit Masonry.

AASHTO T 22-

Compressive Strength of Cylindrical Concrete Specimens.

ASTM C39 /

C39M - 11

Standard Test Method for Compressive Strength of
Cylindrical Concrete Specimens.

ASTM C270 -

Standard Specification for Mortar for Unit Masonry.

ASTM A884 /

A884M - 06

Standard Specification for Epoxy Coated Steel Wire and
Welded Wire Reinforcement.

Table 6-2: Designations and titles for BS and BS EN standards that apply to masonry works

BS Designation

BS EN

Designation

Title

BS EN 1015-

10:1999

Methods of test for mortar for masonry. Determination of
dry bulk density of hardened mortar.

6.2

Concrete Block and Brick Masonry

6.2.1

Description

Concrete block and brick masonry shall consist of concrete blocks or brick laid in cement mortar,
and may be unreinforced or reinforced with steel. Block and brick pavements are not included
under this designation.

6.2.2

Materials

6.2.2.1

Concrete Block

Concrete blocks shall be hard, durable, and clean with sharp, well-defined edges, and free from
any cracks, flaws, or other defects. Unless otherwise specified in the Contract Documents, their
dimensions shall be 400 mm long by 200 mm wide by 200 mm tall, or such other dimensions shall
be approved by the Engineer.

Unless otherwise specified in the Contract Documents or approved in writing by the Engineer, all
concrete block for masonry construction shall be Type I moisture controlled units (Grade N-I) that
meet the requirements of ASTM C90

– 11b. The value of

f΄

(specified compressive strength of

masonry) shall be as shown in the Contract Documents and shall be verified by means of prism
testing. Prism shall be a sample assembly of masonry units, mortar joints and grout.

Concrete block units should be protected from rain or other moisture during storage on or off the
job site to ensure that they will meet the Type I moisture requirements at the time they are placed
during construction.

6.2.2.2

Brick

Brick for masonry construction shall conform to the Specification for Building Brick (solid masonry
units made from clay or shale) AASHTO M 114 -07 (ASTM C62 - 12), Concrete Building Brick
(ASTM C55 - 11), or Solid Load-Bearing Concrete Masonry Units (ASTM C90

– 11b). Type and

grade of the brick to be furnished shall be as specified in the Contract Documents.

Bricks shall have a fine-grained, uniform, and dense structure, free from lumps of lime, laminations,
cracks, checks, soluble salts, or other defects that may in any way impair their strength, durability,
appearance, or usefulness for the purpose intended. Bricks shall emit a clear, metallic ring when
struck with a hammer.

6.2.2.3

Concrete Masonry Units

Concrete masonry units for use in manholes, inlets, and similar structures shall meet the
requirements of ASTM C139 - 10.

6.2.2.4

Reinforcing Steel

Reinforcing steel shall be of the strength, spacing, dimensions and type as shown in the Contract
plans. Reinforcing steel used in the construction of concrete block or brick masonry structures shall
conform to the applicable requirements for reinforcing in Chapter 5, Reinforcing Steel, of these
standard specifications.

6.2.2.5

Mortar and Grout

Mortar and grout ingredients and mix design shall meet the requirements of Article 4.3.10.4 of
Chapter 4, Concrete Works, of these standard specifications, for the class and application types as
otherwise specified in these Standard Specifications, as shown on the Contract plans or as
included in the Particular Specifications.

a. Sampling and Testing

Grout and mortar testing shall meet the sampling and testing requirements specified in Article
4.3.10.4 of Chapter 4, Concrete Works, of these standard specifications, and as may be modified
by the requirements below, if so directed by the Engineer.

1. Mortar

Unless otherwise specified in the Particular Specifications or shown on the Contract plans,
mortar shall have a minimum 28-day compressive strength of 12.5 mPa, based on the
average of three specimens tested in accordance with the requirements of ASTM C780 -
11. Field samples shall be obtained using the following procedure:

i. Spread 12.5 mm or the thickness of the mortar joint of mortar on masonry units.

ii. After one minute, remove the mortar and compress it into a 50 mm by 100 mm cylinder

(or equivalent cube as per test procedure per BS EN 1015-10:1999) in two layers using
the flat end of a rod or fingers, being sure to see that the mold is solidly filled.

iii. Lightly tap the cylinder immediately, and maintain it in a damp condition.

iv. After 48 hours, remove the mold and store it in clean water until testing.

2. Grout

When required by the Contract documents or requested by the Engineer, the Contractor
shall manufacture grout prisms for testing. Prisms shall be manufactured at the site during
construction using the following procedure:

i. Place masonry units that have the same moisture condition as those already placed on a

non-absorptive base to form a void for a square prism, with a height twice the side of the
masonry unit and a minimum side of 75 mm.

ii. Line the side faces of the prism with a permeable paper or porous separator to allow

water passage through the liner into the masonry units.

iii. Fill the prism with a fully-representative grout sample in two layers. Puddle each layer to

eliminate air voids.

iv. Level off the specimen and maintain it in a damp condition.

v. Remove the prisms from the masonry units after 48 hours and deliver them to the

Engineer.

Grout prisms shall be tested in accordance with the provisions of AASHTO T 22 - 10
(ASTM C39/C39M - 11). Grout shall have attained a compressive strength of 13.8 MPa at
28 days, unless otherwise specified in the Contract Documents.

6.2.3

Construction

6.2.3.1

General

a. Brick Masonry

Foundations shall be constructed firm and dry. All brick shall be damp at the time of laying. Bricks
shall be laid in courses in full, close, uniform joints of mortar. Adjoining courses shall break joints
by one-half length, as near as practicable. Courses shall be level in all places, except where

otherwise  directed.  All  exposed  surfaces  shall  be  smooth  and  clean,  and  the  tie  joint  shall  not
exceed 12.5 mm in width. Broken or chipped bricks shall not be used in the faces of the masonry.
Joints  shall  be  cleaned  and  pointed  before  the  mortar  sets.  Exposed  surfaces  of  the  bricks  shall
not be smeared with mortar forced out of the joints or that used in pointing, but shall be kept clean
and  free  from  mortar  stains.  For  straight  masonry  walls,  at  least  one  course  in  seven  shall  be  a
header course.

b. Concrete Block Masonry

When shown on the Contract plans and/or in the Particular Specifications, masonry walls may be
constructed of hollow concrete blocks instead of bricks. Applicable construction details shall be the
same as for brick masonry.

c. Manholes, Inlets, and Catch Basins

Brick  masonry  for  manholes,  inlets,  and  catch  basins  shall  conform  to  details  shown  on  the
Contract  plans.  Construction  requirements  shall  be  as  specified  in  Section  12.4  of  Chapter  12,
Storm  Water  Drainage,  of  these  standard  specifications.  Where  shown  on  the  Contract  plans,  a
plaster coat shall be applied to the faces of these and similar structures. Mortar for this coat shall
be  of  the  same  mix  as  used  in  laying  the  brick,  and  the  coat  shall  be  no  less  than  6  mm  thick.
Before  applying  the  plaster  coat,  the  brick  shall  be  thoroughly  wetted  and  the  surface  allowed  to
dry sufficiently to ensure a proper bond of the plaster coat.

Full mortar beds shall be provided for setting castings required by the Contract plans. Castings
shall be set carefully to the required elevations.

6.2.3.2

Mixing Mortar

Proportions of materials, water retention, workability, and related requirements shall be in such a
manner as to produce the specified strength. Before commencing work, the Contractor shall have
the mortar mix approved by the Engineer. Mortar mix and mixing requirements shall meet the
requirements included in Article 4.3.10.4 of Chapter 4, Concrete Works, of these standard
specifications, and as specified herein.

Mortar shall be hand- or machine-mixed, as may be required by the Engineer. In the preparation of
hand-mixed  mortar,  the  sand  and  cement  shall  be  thoroughly  mixed  together  in  a  clean,  tight
mortar  box  until  the  mixture  is  of  uniform  color,  after  which  clean  water  shall  be  added  in  such
quantity  as  to  form  a  stiff  plastic  mass.  Machine-mixed  mortar  shall  be  prepared  in  an  approved
mixer  and  shall  not  be  mixed  less  than  three  minutes  or  more  than  10  minutes.  Mortar  shall  be
used within 1.5 hours after mixing and before final setting begins. Re-tempering of mortar shall be
performed as necessary to maintain proper consistency during placement.

6.2.3.3

Laying Block and Brick

Blocks  or  bricks  shall  be  laid  in  such  a  manner  as  will  thoroughly  bond  them  into  the  mortar  by
means of the “shove-joint” method; “buttered” or plastered joints shall not be permitted. All clay or
shale  brick  shall  be  thoroughly  saturated  with  water  before  being  laid.  Dampening  of  concrete
masonry  units  before  or  during  construction  shall  not  be  permitted  unless  approved  by  the
Engineer.  Headers  and  stretchers  shall  be  arranged  to  thoroughly  bond  the  mass,  and  unless
otherwise  specified,  alternate  headers  and  stretchers  shall  be  used  with  consecutive  courses
breaking joints. Other types of bonding, as for ornamental work, shall be as may be specified in the
Particular Specifications or as shown on the Contract plans.

All joints shall be completely filled with mortar. They shall not be less than 6 mm wide and not more
than 19 mm thick, with the thickness uniform throughout. All joints shall be finished properly as the
work progresses, using the “weather” joint. Exposed faces shall be neatly struck.

No spalls or bats shall be used except for shaping around irregular openings or when unavoidable
to finish out a course, in which case full bricks shall be placed at the corners, with the bats placed
in the interior of the course.

Each masonry unit shall be adjusted to its final position while the mortar is still soft and plastic.
Units that are disturbed after the mortar has stiffened shall be removed and laid again in fresh
mortar.

Vertical cells to be filled with grout shall be aligned to provide a continuous unobstructed opening.

Piers and walls may be built of solid brick work, or may consist of a brick or block shell backed with
concrete or other suitable material as shown on the Contract plans. All details of the construction
shall be in accordance with approved practices and to the satisfaction of the Engineer.

6.2.3.4

Placement of Reinforcement

Prior to and during grouting, the reinforcing steel shall be securely held in position at the top and
bottom and at intermediate points not exceeding 200 bar diameters or 3 meters apart. Bars shall
be maintained clear of the cell walls and within ±12.5 mm of their planned position transverse to
the wall and within ±50 mm of their planned position longitudinal to the wall.

6.2.3.5

Grouting of Voids

Grouted masonry shall be constructed in such a manner that all elements of the masonry acts
together as one structural element.

Prior to grouting, the grout space shall be clean so that all spaces to be filled with grout do not
contain mortar projections greater than 12.5 mm, mortar droppings, or other foreign material. Grout
shall be placed so that all spaces to be grouted do not contain voids.

Grout materials and water content shall be controlled to provide adequate fluidity for placement
without segregation.

Size and height limitations of the grout space or cell on the average shall not be less than as
shown in Table 6-3. Higher grout pours or smaller cavity widths or cell sizes than shown in Table 6-
3 may be used when approved by the Engineer, if it is demonstrated that grout spaces are properly
filled.

When required by Table 6-3, cleanouts shall be provided in the bottom course at every vertical bar,
but shall not be spaced more than 813 mm on center for solidly grouted masonry. Cleanouts shall
be of sufficient size to allow removal of debris.

Units may be laid to the full height of the grout pour, and grout shall be placed in a continuous pour
in grout lifts not exceeding 1.8 meters. If construction joints are used in columns of grout, they shall
be located at least 38 mm below the level of a mortar bed joint.

Segregation of the grout materials and damage to the masonry shall be avoided during the
grouting process.

Grout shall be consolidated before the loss of plasticity in a manner to fill the grout space. Grout
pours greater than 300 mm in height shall be mechanically reconsolidated to minimize voids due to
water loss. Grout not mechanically vibrated shall be puddled.

In non-structural elements, mortar of pouring consistency may be substituted for grout when the
masonry is constructed and grouted in pours of 300 mm or less.

Vertical barriers of masonry may be built across the grout space. Grouting of any section of wall
between barriers shall be completed in one day with no interruption longer than one hour.

Table 6-3: Grouting limitations

Least Clear Dimensions

Grout

Type

Grout Pour Maximum

Height

metre

Width of Grout Space,

Cell

Dimensions,

mm × mm

Cleanouts

Required

Fine

0.3

38 × 50

Least Clear Dimensions

Grout

Type

Grout Pour Maximum

Height

metre

Width of Grout Space,

Cell

Dimensions,

mm × mm

Cleanouts

Required

Fine

1.5

38 × 50

Fine

2.4

38 × 76

Yes

Fine

3.6

44 × 76

Yes

Fine

7.3

76 × 76

Yes

Coarse

0.3

38 × 76

Coarse

1.5

63 × 76

Coarse

2.4

76 × 76

Yes

Coarse

3.6

76 × 76

Yes

Coarse

7.3

76 × 101

Yes

6.2.3.6

Copings, Bridge Seats, and Backwalls

In general, tops of retaining walls, abutment wingwalls, and similarly exposed brick or block work
shall be provided, with either a stone or concrete coping as specified in the Contract documents.
Underside of coping shall have a batter or drip bead at least 25 mm beyond the face of the block or
brick  work  wall.  Coping  on  an  abutment  backwall  shall  commonly  have  no  projection  beyond  its
bridge  seat  face.  Unless  otherwise  specified,  when  concrete  is  used,  it  shall  conform  to  the
requirements  for  Class  C35/20  concrete  specified  in  Section  4.3.9  and  other  applicable
requirements  of  Chapter  4,  Concrete  works.  For  thin  copings,  mortar  of  the  same  proportions  as
used for laying the block or brick may be used to produce precast sections no less than 0.9 m or
more than 1.5 m in length. No coping shall be less than 100 mm thick.

Copings of piers and abutment bridge seats may be of ashlar stone work or of concrete conforming
to the requirements of Articles 6.2.3.7 and 6.2.3.8 respectively. Unless otherwise shown in the
Contract documents, concrete shall be used.

6.2.3.7

Ashlar Stone Copings

Ashlar masonry is composed of rectangular stones laid with mortar in horizontal courses. Ashlar
masonry shall consist of first-class cut stone masonry laid in regular courses, and shall include all
work in which the individual stones (as distinguished from rubble masonry) are dressed or tooled to
exact dimensions.

Stone for ashlar masonry shall be reasonably fine grained and uniform in color. Preferably, stone
shall be from a quarry, the product of which is known to be of satisfactory quality. Stone shall be of
such character that it can be brought to such lines and surfaces, whether curved or plane, as may
be required. Any stone having defects that have been repaired with cement or other materials shall
be rejected.

Each stone shall be free from depressions and projections that might weaken or prevent it from
being properly bedded, and shall be of a shape to meet the requirements for the class of masonry
specified.

Stones for copings of wall, pier, and abutment bridge seats shall be carefully selected and be fully-
dimensioned stones. On piers, not more than two stones shall be used to make up the entire width
of coping. Copings of abutment bridge seats shall be of sufficient width to extend at least 100 mm
under the backwall. Each step forming the coping of a wingwall shall be formed by a single stone
that shall overlap the stone forming the step immediately below it by at least 300 mm.

Tops  of  copings  shall  be  given  a  bevel  cut  at  least  50 mm  wide,  and  beds,  bevel  cuts,  and  tops
shall  be  fine-finished.  Vertical  joints  shall  be  smooth-finished,  and  the  copings  shall  be  laid  with
joints  no  more  than  6.5 mm  thick.  Preferably,  undersides  of  projecting  copings  shall  have  a  drip
bead.

Joints in copings shall be located so as to provide no less than a 300 mm bond with the stones of
the under course, and so that no joint will come directly under the superstructure masonry plates.

a. Shipment and Storage of Stone

Quarry operations and delivery of stone to the point of use shall be organized to ensure deliveries
well ahead of masonry operations. Sufficiently large stocks of the specified stone shall be kept on
the site at all times to permit adequate selection of stone by the masons.

All stone shall be kept free from dirt, oil, or any other injurious material that may prevent the proper
adhesion of the mortar or detract from the appearance of the exposed surfaces.

b. Surface Finishes of Stone

Stone surface finishes are defined as follows:

1. Smooth-finished: Having a surface in which the variations from the pitch line do not exceed

1.5 mm.

2. Fine-finished: Having a surface in which the variations from the pitch line do not exceed 6.5

mm.

3. Rough-finished: Having a surface in which the variations from the pitch line do not exceed

12.5 mm.

4. Scabbled: Having a surface in which the variations from the pitch line do not exceed

19 mm.

5. Rock-faced: Having an irregular projecting face without indications of tool marks.

Projections beyond the pitch line shall not exceed 76 mm and no part of the face shall
recede back of the pitch line.

c. Selection and Placing of Stone

Each  stone  shall  be  cleaned  and  thoroughly  saturated  with  water  before  being  set,  and  the  bed
that  is  to  receive  it  shall  be  clean  and  well  moistened.  All  stones  shall  be  well-bedded  in  freshly
made mortar. Mortar joints shall be full and the stones carefully settled in place before the mortar
has  set.  No  spalls  shall  be  permitted  in  the  beds.  No  pinning  up  of  stones  with  spalls  shall  be
permitted in beds.

Stone shall not be dropped upon or slid over the wall, nor will hammering, rolling, or turning of
stones on the wall be permitted. Stone shall be carefully set without jarring the stone already laid,
and shall be handled with a Lewis tool or other appliance that will not cause disfigurement.

In case any stone is moved or the joint broken, the stone shall be taken up, the mortar thoroughly
cleaned from the bed and joints, and the stone reset in fresh mortar.

d. Dowels and Cramps

Where required, coping stone, stone in the wings of abutments, and stone in piers shall be secured
with wrought-iron cramps or dowels as indicated in the Contract plans.

Dowel holes shall be drilled through each stone before the stone is placed and, after it is in place,
such dowel holes shall be extended by drilling into the underlying course not less than 150 mm.

Cramps shall be of the shapes and dimensions shown in the Contract plans or approved by the
Engineer. They shall be inset in the stone so as to be flush with the surfaces.

Cramps and dowels shall be set in lead, care being taken to completely fill the surrounding spaces
with the molten metal, or shall be rigidly anchored by other means approved by the Engineer.

6.2.3.8

Concrete Copings

Copings, bridge seats, and backwalls shall be of the material specified in the Contract documents,
and when not otherwise specified, shall be of C35/20 concrete, which shall conform to the
requirements of Section 4.3.9 and other applicable requirements of Chapter 4, Concrete Works, of
these standard specifications.

Concrete copings shall be made in sections extending the full width of the wall, no less than
300 mm thick, and from 1.5 to 3.0 m long, or as shown on the Contract plans. Sections may be
cast-in-place or precast and set in place in full mortar beds.

6.2.3.9

Weep Holes

All  walls  and  abutments  shall  be  provided  with  weep  holes.  Unless  otherwise  specified  in  the
Contract  documents  or  directed  by  the  Engineer,  the  weep  holes  shall  be  placed  at  the  lowest
points  where  free  outlets  can  be  obtained,  and  shall  be  spaced  no  more  than  3.0 m  center-to-
center. At each weep hole, a minimum of 0.057 m

of permeable material encapsulated with filter

fabric shall be placed.

6.3

Rock Masonry

6.3.1

Description

Rock masonry shall consist of rock laid in a bed of mortar, dressed, pointed, cured, and
constructed in conformance to the Contract plans, the Particular Specifications, the direction of the
Engineer, and these Standard Specifications.

6.3.2

Materials

Rock masonry materials shall conform to the requirements established in Table 6-4.

Table 6-4: Material requirements for rock masonry

Material

Requirements

Cement, fly ash, admixtures

Section 4.3 of Chapter 4, Concrete Works.

Mortar

Article 4.3.10.4 of Chapter 4, Concrete Works

ASTM C270 - 12, Type M or S only

Class G6 grout

Article 4.3.10.4 of Chapter 4, Concrete Works

Maximum water-to-cement ratio of 0.44.

6.3.2.1

Rock for Masonry Structures

Contractor shall furnish sound, durable rock that meets the requirements of the  Contract plans or
as required in the Particular Specifications.  Rock native to the vicinity of the work similar in texture
and  colour  to  native  rock  is  preferred.  Dimensioned  masonry  rock  shall  be  free  of  reeds,  rifts,
seams,  laminations,  and  minerals  that  may  cause  discolouration  or  deterioration.  Rock  with
depressions or projections that might weaken it or prevent it from being properly bedded shall not
be used.  Contractor shall submit samples to the Engineer for approval and construction shall not
begin until written approval is received.

Rocks  shall  be  furnished  in  the  sizes  and  face  areas  necessary  to  produce  the  general
characteristics and appearance indicated on the  Contract plans. Unless otherwise specified, rock
fragments shall meet the dimensional requirements in Table 6-5.

Table 6-5: Physical requirements for rock for masonry

Dimension

Requirements

Minimum thickness

125 mm

Minimum width

300 mm or 1.5 times the thickness, whichever is greater

Minimum length

1.5 times the width

At least half of the rocks shall have a volume greater than, or equal to, 0.03 m

. When headers are

required, furnish headers with lengths no less than the width of bed of the widest adjacent stretcher
plus 300 mm.

6.3.3

Construction Requirements

Excavation and backfill shall be performed per  Sections 2.4 and 2.5 of Chapter 2, Earthworks, of
these standard specifications. Foundation bed shall be prepared normal to, or in steps normal to,
the  face  of  the  masonry.  Where  foundation  masonry  is  used,  the  bearing  surface  shall  be
thoroughly cleaned and shall be wetted immediately before spreading the mortar bed.

Prior to placing rocks, the Contractor shall clean and moisten the bed.

Unless otherwise shown on the Contract plans, mortar shall be proportioned and supplied per
ASTM C270 - 12, Type M or S only, and may be preblended or mixed on site. Mortar bed shall not
lay longer than 45 minutes or until mortar begins to set before placing rock.

Rocks shall be placed to provide a uniform pattern and color. To provide sufficient variety of rocks
for the masons, the Contractor shall maintain an adequate inventory of the rock on site. When rock
is added, the new rock shall be mixed with the existing rock in a uniform pattern and color. All
rocks shall be cleaned thoroughly and moistened immediately before placing. When removing and
resetting rock masonry, the Contractor shall use hand tools to clean the exposed faces of the rocks
of all mortar before resetting.

Mortar shall be spread to the thicknesses of beds and joints for face stones shown in Table 6-6.
Bed of each course shall be uniform in thickness.

Joints in dimensioned masonry shall be vertical. In all other masonry, joints may be at angles with
the vertical from 0

to 45

Cross beds for vertical walls shall be level. Beds for battered walls may vary from level to normal to
the batter line of the face of the wall.

Rocks shall be laid with the longest face horizontal and the exposed face parallel to the masonry
face, and then the joints shall be flushed with mortar.

Contractor shall take care to not jar or displace rocks that are already set. If a rock is loosened
after the mortar has taken initial set, it shall be removed, cleaned of mortar, and relaid with fresh
mortar.

Dressing shall remove all thin or weak portions.  Face rock bed and joint lines shall be dressed to
the maximum variation from true line shown in Table 6-6.  The Contractor shall dress face rock as
follows:

a. Dress bed surfaces to a depth of 75 mm, normal to the face, after which the departure from

normal may not exceed 25 mm in 300 mm for dimensioned masonry or 50 mm in 300 mm
for all other classes.

b. Dress joint surfaces normal to the face to a depth of 50 mm, after which the departure from

normal may not exceed 25 mm in 300 mm.

Table 6-6: Rock masonry classes and construction requirements

Class

Stones and

Laying

Bed

Thickne

(mm)

Joint

Thickne

(mm)

Dressing

(mm from true

line, angle to bed)

Rounding

corners where

bed and joint

lines meet

Dimensione

d masonry

Stones are cut in

≥ 2 dimensions,

laid in broken-

course pattern

10 to 25

19 to 25

Reasonably true,

normal to bed

No rounding

Class A

masonry

Stones are

shaped, dressed

to 5 mm

13 to 50

13 to 38

5 mm,

≥ 45

to bed

surface

No rounding

Class B

masonry

Stones are

shaped, dressed

to 20 mm

13 to 50

20 mm, ≥ 45

bed surface

Radii ≤ 25 mm

Rubble

masonry

Stones vary in

size and shape,

laid in random

courses

13 to 64

40 mm, ≥ 45

bed surface

Radii ≤ 40 mm

To  finish  exposed  surfaces,  the  Contractor  shall  remove  all  drill  or  quarry  marks  from  exposed
faces  and  pitch  face  stones  to  the  line  along  all  beds  and  joints.    Classes  for  finishing  exposed
faces  are  as  defined  in  Table  6-7,  and  shall  be  executed  as  shown  in  the  Contract  plans  or  the
Particular Specifications, or as directed by the Engineer.

Table 6-7: Rock masonry finishing classes

Class

(abbreviation)

Approximate

spacing for point

depressions

Maximum surface

variation from the pitch

line

Appearance

Fine pointed (FP)

10 mm

±3 mm

Medium pointed
(MP)

15 mm

±5 mm

Coarse pointed
(CP)

30 mm

±10 mm

Split or seam face
(S)

+20 mm

-0mm

Smooth, no tool marks

Rock faced (RF)

+Defined*

-0 mm

Irregular, no tool marks,
projections with no
concave surfaces below
the pitch line

*Projections beyond the pitch line shall be specified, i.e. “Class 40RF” means no projections exceeding
40mm beyond the pitch line. Where a "variable rock face" is specified, the Contractor shall uniformly
distribute stones of the same height of projection.

To point  new joints, the Contractor shall crown the mortar  in the joints on top surfaces slightly at
the  centre  of  the  masonry  for  drainage.  For  raked  joints,  the  Contractor  shall  squarely  rake  all
mortar in exposed face joints and beds to the required depth. For weather joints, the joints shall be
slightly  raked.  Mortar shall  not remain  flush  with  the rock  faces.  All  face  rock  shall  be  cleaned  of
mortar stains while the mortar is fresh. After the mortar sets, the Contractor shall clean again using
wire brushes and acid. Masonry shall be protected during hot or dry weather kept wet for at least 3
days after the work is completed.

To repoint joints, the Contractor

shall remove loose mortar from joints using a small mason’s

chisel, small pneumatically-power chisel, or other raking tool approved by the Engineer. Power

Abu Dhabi, United Arab Emirates. STANDARD CONSTRUCTION SPECIFICATIONS (PART 1 - ROADS, Second Edition 2020) - page 30