Definitions and abbreviations
PM: Project Manager
CM: Construction Manager
PE: Project Engineer
QCE: Quality Control Engineer
SE: Site Engineer
QA QC: Quality Assurance and Quality Control
PPE: Personal Protective Equipment
HSE: Health, Safety, and Environment
ITR: Inspection Test Report
ITP: Inspection Test Plan
Safety Requirements for Block Work
- Prior to the construction of the block wall, a scaffold spanning the work area is constructed up to the level of the construction.
- The scaffold is to be designed to be able to hold the material that is to be used in the block wall construction.
- Scaffolding will be erected so that it will allow each mason free access without being tied off.
- All workers working at height will have to wear safety harnesses with lanyards.
- The area where the block work activities are in progress will be barricaded.
Masonry block work method of Installation
- Ensure that block work material, sample and method statement, and masonry accessories are approved.
- Masonry delivered to the site shall be carefully unloaded & handled to prevent chipping and breakage and random sample to be sent for testing.
- Masonry block work units shall be stored in a dry location on plank platforms of adequate size.
- Verify that all reinforcing, anchors, dowels, lintels, flashings, and other built-in items are on hand, of proper size, and locations established.
- Before the commencement of block work ascertain the nature and location of all MEP openings and built-in items.
- A Mock-up wall of typical wall type shall be constructed and approval to be taken from the client.
- After approval of block work mock-up proceed with masonry works.
- Concrete block masonry work shall match with approved mock-up wall.
Block work procedure:
- The surveyor will mark out the layout for the block work using current layout drawings
- In a dry and hot climate, masonry units will be wetted before laying in order to prevent quick drying and shrinkage of cement-based mortars.
- 200 thick thermal blocks shall be used for all the external walls or as per approved shop drawings details
- An approved Damp Proof Course (DPC) material shall be pre-laid into the base of the wall along the alignment of the block wall. The width of the DPC material shall be the same as the particular thickness of the blocks specified on the approved shop drawing.
- The first layer of blocks to be solid blocks and it should be fully set out with proper alignment
- Blocks shall be properly laid on a full bed of mortar. Mortar joint thickness for the general-purpose mortar will be 8mm to 12mm
Mortar Mixing for Wall Block Work:
- The mortar mix ratio is 1:6 OPC / Sand for CMU blocks and 1:4 OPC / Sand for thermal blocks or as specified.
- Add and mix thoroughly and uniformly in enough water to make mortar tightly ball in man’s hand and to lightly ooze through fingers as the hand is closed
- Mix no more mortar at a time than can be used within one and a half hours.
- Mortar not used within the one and half hour time shall be disposed of. Do not re-temper mortar.
- Place masonry to lines and levels indicated by the surveyor.
- Masonry units shall be set out with a storey rod so that coursing lines up at steel shelf angles, sills, heads of windows, and doors with full courses.
- Masonry units will be assembled together and overlapped, so the vertical joints are staggered from course to course. At the corners and wall intersections, the overlapping should be the minimum width of the units. Only cut dimension units will be used at these locations.
- Horizontal anchors for the masonry block walls will be respected as per the specifications
- All the horizontal joints shall be leveled and vertical joints shall be aligned during construction
- Cutting of masonry will be done by a power-driven masonry saw.
- Walls shall be kept level at all times. Do not install any portion of the wall more than 1.2 m in height on any particular day. Carry up walls in a uniform manner, no part being raised more than 1000 mm above any adjacent un-built course, and no area of walling higher than 600 mm, above any course which is not fully set Angles and reveals shall be kept true, square, and plumb. Broken walls must be laid up with a lead.
- Walls shall be constructed as true planes and when tested with a 3000 mm straight edge placed anywhere on the wall in any direction shall be true to place within 3mm and plumb within 4 mm. Each horizontal joint shall be level and at the same height in all walls around the room and true to the lines and dimensions indicated on the drawings. Unsatisfactory work shall be removed and replaced.
- Intersecting concrete block walls shall be tied together in a masonry bond. Extend masonry partitions, unless shown otherwise, to within 20 mm of the underside of the structure. Fill the 20 mm gap with insulation under 25% compression, so placed that space is left on each side of the finished wall to accept joint sealant.
- Install reinforced concrete lintels over openings in concrete block walls. Lintels shall a minimum of 200 mm bearing on supporting masonry. Install solid concrete masonry bearing blocks at the jambs of all concrete blocks. The bearing blocks are to be of the same material as the adjacent wall surfaces.
How to provide lateral support:
- Intersecting bearing walls shall be tied together with a prefabricated “Tee Section” of wall reinforcement or strap anchor set in the second bed course and every third course thereafter, the full height of the wall.
- Tops of masonry walls up to 45 mm thick shall be secured to cast-in-place concrete slabs above with strap anchors securely fixed to the slab and securely embedded into mortar joints of the wall. Space anchors not more than 600 mm apart.
- Block work more than 6 m in height shall be reinforced with a reinforced concrete stiffening framework comprising 200 x 200 mm verticals at a 4.00-meter center and 200 x 300 mm horizontals at mid-height or at every 3.00 meters in case wall height is bigger than 5.00 meters as per the approved shop drawings. When the distance between the structural columns is more than 6.0 meters that is the width of the panel Block masonry is more than 6.0meter, and the height and the height of the panel is more than 4.0 m, provide non-structural columns (200×200) not exceeding 6.0 m on centers as stiffeners.
- Stiffener columns and beams shall be provided according to the approved shop drawings and should be approved before any casting of stiffener columns and lintels.
MEP Cut out in Block Walls:
- Maintain openings as per the drawing and cut units to accommodate frames, conduits, fixtures, recesses, and other MEP work inside the wall block work.
Doors in Block Walls:
- As Work progresses, install metal door frames, fabricated metal frames, window frames anchor bolts, plates, conduits, pipes, and other built-in items into Work.
- All frameworks shall be anchored both jams and set plumb and true. Block work shall be built to the respective dimension, thickness and height mentioned on the drawing
Curing Block Walls:
- Damp cure the block works for 3 days, lintels and sills for 7 days as per the project manager’s specifications.
Cleaning of block work:
- As the work proceeds, carefully remove mortar splashes from masonry surfaces and adjoining surfaces. After completing each section of the wall block work, clean down surfaces and make good where required.
Materials required for these works:
- Solid and/or Hollow Concrete Masonry Blocks
- Thermal Blocks
- Damp Proof Course
- Steel masonry accessories, head ties, lateral ties, etc.
- Cement-based Non-shrink grout etc.
Plant and equipment required for these works:
- Nail Gun
- Table Grinder for block cutting
- Scaffolding Platforms
- Electric drills
- Trowels & Hand tools
- Mixer machine
- Masonry saw
- Mason square
- 3m long Aluminium straight edge
- Spirit level
- Water level
- Measuring tape
- Line dory
- Plumb bob
- Calibrated survey instruments.
The capacity/size of the above equipment shall be judged in accordance with site conditions, requirements, and availability at the time of execution of block work activity.