METHOD STATEMENT
FOR CONCRETE MASONRY UNIT
1. Scope:
This procedure relates the concrete masonry unit assemblies and these required properties
including mortar and reinforcement accessories.
2. REFERENCE DOCUMENTS
2.1. Documents establish by the contractor
A. Execution documents (SBG/SENLABO BTP)
Dar specifications 04810
Material test report
Design mix
B. Documents du Plan Quality (SBG/SENLABO BTP)
ITP
NCR
2.2. Acceptance criteria’s of blocks
Compressive strength 13.1 MPa for net area or 7.5 MPa for gross area
Size +/- 10mm on nominal size
No crack, no chips, and no deformed shape
Fire rate if require
Density 2002 kg/cu.m
2.3. Acceptance criteria’s of wall
Tolerance:
Cross section dimension 12mm to 6mm
Location of wall +/- 12mm
Location in elevation +/- 6mm in the story heath or +/- 12mm in the total
For bed joint and top surface do not varied 6mm in 3m or 12mm maximum
For vertical line and surface do not varied from plumb by more than 6mm in 3 m; 9mm
in 6m an 12mm au maximum
For vertical line such as corner door and expansion joint and control joint do not vary
from plumb by 3 mm in 3m ; 6mm in 6m or 12 mm maximum
For line surface do not varied from do not varied from straight by more than 6mm in 3
m; 9mm in 6m an 12mm au maximum
For joint bed +/- 3mm in indicated joint stickiness and 12mm maximum
3. PREVIOUS OPERATIONS
Cleaning the surfaces of slab or ground beams where the wall will be build
scarified if it is smooth
The surveyor give the alignment and the exact location of the wall
4. MANPOWER
Site engineer
Surveyor
Foreman
Masons
Helpers/ labors
5. MASONRY EQUIPMENT
scaffoldings with complete accessories and approved by the engineer
Tooling of masonry (trowel, plumb line, and hammer. Ruler, niveau….)
Mortar contains, Brush, sponge
Sawing block machine
Mortar mixer
Material
Approved blocks
Approved and tested sand
Cement
Admixture
Reinforcement and accessories
6. PROCEDURE FOR MASONRY LAYING AND REINFORCEMENT
6.1 Laying masonry walls
Lay unit after cleaning all faces and use only block of correct size
Bricks shall be laid on a full bed of mortar and all cross joints and collar joints should be
filled.
Immediately after the brick is laid, excess mortar should be struck off the external face of
the work and off the internal face of leaves of cavity walls.
Solid and cellular blocks shall normally be laid on a full bed of mortar and cross joints and
collar joints should be filled.
All beds of mortar shall be level and straight and vertical joints formed so as to present a
uniform pattern of bond.
Units shall be adjusted in position only while the mortar is still soft and plastic.
Any unit disturbed after mortar has begun to set shall be removed, cleaned and re-laid
with fresh mortar.
Damaged units shall not be re-used.
No portion of masonry shall be built up more than 7 blocks high at a time.
Work which is stopped and later resumed shall not be toothed and bonded together, but
the work shall be racked back in preparation for re-commencement.
All masonry to receive plaster, stucco or any other such applied finish shall have
sufficiently rough-keyed surfaces and/or joints.
Exposed masonry shall be of uniform texture and color or a uniform blend within the
ranges accepted for these characteristics and shall be obtained from one source or
manufacturer.
No section of the work shall be constructed with a mixture of units from differing
sources. Batches from the same manufacturer or source shall be mixed to ensure that no
patchiness results from allowable natural manufacturing variations in color.
The absorption rates of masonry units shall be adjusted by previously wetting to ensure a
good solid bond with the mortar.
The external surface of buried CUM shall be coated with approved bituminous paint to
prevent capillary water climbing
6.2- Composite masonry
Provides ties as shown installed in horizontal joint min 0.25m and max 610 mm
Provides masonry joint reinforcement installed in horizontal mortar joints
Provides masonry header bonding
Provides interlocking masonry unit in corner
Provides individual or rigid metal in intersection and abutting walls
6.3- Masonry joint reinforcement
Extending 305mm beyond opening in additional to continuous reinforcement;
Interrupt joint reinforcement at control and expansion joints unless otherwise indicate
Provides continuity at wall by using prefabricated T-shaped units
Provides continuity at comers by using prefabricated L-shaped units
Cut and bend reinforcement unit as directly by manufacturers for continuity at returns,
offsets columns fireproofing, pipe enclosures and other special conditions.
6.4-Anchors masonry to structural steel and concrete
Provides an open spaces not less than 25mm wide between masonry and structural steel
Anchor masonry with anchor embedded in masonry joint and attaché to structure
Spaces anchors as indicated, but not more than 610 mm vertically and 915mm horizontally
6.5- Control and expansion joints
Install control expansion joint material in unit masonry as masonry progresses. Do not allow
material to span control and expansion joints without provision to allow for in-place
concrete wall or partition movement
6.6-Lintels
Will be install where shown and where the opening of more than 305mm for brick-size units
and 610mm for block-size units are shown without structural steel or other supporting lintels
6.7- Flashing, weep holes, cavity drainage and vents
Install embedded flashing and weep holes in masonry at shelf angles lintels and ledges other
obstruction to downward flow of water in wall and where indicated ,install vents at self
angles ,ledges ,and other obstructions to flow of air in cavities and where indicated.
6.8-Repairing and cleaning pointing
All unconfirmed units will be removed and replace
Point up joint, including corners, opening, and adjacent construction to provides a neat,
uniform appearances
Clean unit masonry as work progresses by dry brushing to remove mortar fins and smears
before tooling joints
Cure masonry wall with water up to 3 days
