Method Statement for Masonry Block Work | Work Procedure | Blockwork Construction Details | Method Sequence for Block Masonry Work
In this Article today we will talk about the Method Statement for Masonry Block Work | Work Procedure for Masonry Block Work | Method Sequence for Block Masonry Work | Blockwork Wall Construction Details | Block Work in Construction | Concrete Block Work | Types of Block Work.
What is Block Work ?
Block work is most important work for the construction of any building. Concrete blocks are very common building components that are used worldwide. There is a wide variety of size and type used within the construction industry today. Let us look at some examples of units used in block work. Blocks are produced in a range of shapes and sizes.
The face side is usually 450 x 225, the thickness varies from 60 mm up to 150 mm and the weight from 6.3 to 15 kg. They are produced in solid, hollow and multi-cut format. Multi-cuts enable a bolster cut to be made without wastage. Walling built with pre-cast blocks may be divided into two main categories i.e. Load bearing and non- load bearing.
Types of Blocks:
Load bearing blocks are pre-cast in moulds and compacted with the aid of vibration, or moulding machines involving the use of compressed air, or a combination of both. These blocks are usually made of concrete comprised of cement and aggregate. The cement is usually Port and cement and a variety of aggregates are used. Method Statement for Masonry Block Work
Non load bearing block can also be pre-cast in moulds. but others are produced in slab format and cut to size when set. These blocks are usually made with variety of lightweight materials and cement such as Breeze or Clinker waste coke or ash and cement, Burnt clay etc. Method Statement for Masonry Block Work
Advantages of Concrete Block:
Concrete blocks are Versatile, durable and strong, Completely fire resistant, Excellent sound insulation. Also ideal background for dry lining wet finishes and fixings. Inherent thermal mass acts as heat store. These are proven and familiar building method with no risk. Widely and readily available and Cost effective.
Block Work Method of Statement:
Is to define the requirements for supply and laying of concrete block work for the buildings and utilities under the contract no GTC.101/ED/01 Engineering, Procurement, Installation and Commissioning (EPIC) of ____________ Project – Buildings and utilities and support service Phase 1-Utilities.
Concrete block work for buildings and utilities in Service Base Area, Service Berth and F.S.O Marine area and Telecom building.
- Project Approved Drawings
- Qatar Petroleum Standard Specification for Civil Works Vol. I, Section 4
- British Standards BS 6073, BS 4027, BS 12, Bs 1200 table 1, BS 4887, BS 1243 Table-3, BS 743 type-C, BS 3416-type 1, Class A
Required tools for block work:
Below is the equipment involved in the construction of the block works / cavity walls:-
- Nail Gun Method Statement for Masonry Block Work
- Table Grinder for block cutting
- Scaffolding Platforms Electric drills
- Trowels & Hand tools
- Mixer machine
- Wheel barrow
- Masonry saw
- Mason square
- 3m long Aluminum 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.
- Blocks: Solid and Hollow Concrete Masonry Blocks
- Wall Ties
- Damp Proof Course
- Bituminous Paint
- Reinforcement for Block Work
- Mortar Mixes
Specification for Materials:
- Concrete block work shall conform to requirements of BS 6073 . Crushing strength test report shall be submitted to QP engineer for approval before the block are delivered to site. Work Procedure for Masonry Block Work
- Block shall be hollow or solid as per drawings.
- The average compressive strength of 10 sample blocks shall be of 7N/mm2 and no individual bock shall be less than 5.6N/mm2.
- The thickness of the webs and walls shall not be less than 50mm and the volume of the cavities in the block shall not exceed 50% of the gross volume of the block.
- All surfaces shall be flat and rectangular and adjacent surfaces shall be at right angles to one another. Work Procedure for Masonry Block Work
- Unless otherwise specified all block faces shall provide a satisfactory bond for motor, plastering or rendering.
- Each block manufactured from sulphate resisting cement shall be color coded with a green identifying mark.
- Fine and coarse natural aggregates shall comply generally with BS 882.
- The chloride content of the fine and coarse aggregates, tested in accordance with BS 812, part 4, shall not exceed 1.0% of the weight of cement used in manufacturer of the block. Work Procedure for Masonry Block Work
- Sand for motor shall be selected beach or dune sand, washed clean and free from clay, chalk, shells, organic materials and other impurities. The sand shall comply in all respects with BS 1200, table-1.
- Cement shall be Portland cement to BS 12, sulphate resisting cement shall comply with BS 4027. Blockwork Wall Construction Details
- It shall be Potable.
- Wall ties shall be Stainless steel/galvanized steel vertical twist type complying with BS 1243 table 3 Blockwork Wall Construction Details
Damp Proof Course:
- DPC shall be asbestos based bitumen to comply with BS 743 type 3 or plastic type to the approval of the QP-engineer.
- Shall be cold applied black bitumen coating solution to BS 3416 type 1, class A.
Reinforcement for Block Work:
- Reinforcement required to be built into block work and horizontal joints shall be galvanized steel expanded metal type, minimum 24 gauge to the widths specified.
- Mortar mixes shall be accurately gauged by volume using approved gauge boxes.
- The ingredients shall first be mixed dry until thoroughly mixed to a uniform color before water is added to the mix.
- All mortar shall be used within 30 minutes of mixing. No mortar, which has achieved its initial set, shall be used in the work, and no water is to be added to the mortar, after the initial mix. Blockwork Wall Construction Details
- Mortar samples shall be prepared and tested in accordance with BS 4551 and as instructed by the QP-engineer.
- For work below floor slab level and work in contact with the ground: 1 part sulphate-resisting cement: 3 parts sand.
- For all other work : 1 part ordinary Portland cement : 6 parts sand.
- Block work shall be constructed generally in accordance with BS 5628 part 1.1978.
- The area is to be cleaned, all loose materials to be removed.
- Before starting of block work, the area is to be washed with water.
- All block shall be thoroughly wetted with water before they are laid and tops of walls left from previous day work shall be similarly wetted before the new work commences.
- Block work shall rise at the rate of four courses per 900mm. A maximum of 6 courses being built in a section in any one day.
- Walls shall be built in stretcher bond unless otherwise specified.
- Cutting of blocks shall be kept to a minimum. When cutting of blocks is essential, a bolster shall be used in preference to a trowel.
- All units shall be laid on a full bed of mortar in perfectly horizontal courses. All perpend joints shall be in perfect vertical alignment and well filled by buttering the ends of the unit and then sliding into position against its neighbor. Collar joints shall be filled by buttering the stretcher side. Method Sequence for Block Masonry Work
- All joints shall be solidly filled and the thickness of the joints shall not exceed 10mm. All mortar joints shall be finished flush with the general face of the wall unless otherwise specified. Blockwork Wall Construction Details
- Hollow block at jambs, reveals of opening etc shall be filled solid with concrete.
- Curing of block work should be done for at least 7 days.
- The movement joints to be 12mm wide as per position indicated on the drawings. The joints shall be straight vertical and formed with uncut faces of the blocks to each side.
- Expansion joints are to be as per positions indicated on the drawing.
- The expansion joints shall be filled with bitumen impregnated fiberboard to finish 15mm back from each face of the wall. Blockwork Wall Construction Details
- All exposed edges of the expansion joints shall be pointed with two part gun-grade poly sulphide sealing compound 15mm deep neatly finished flush with the wall face and colored if specified on the drawings.
Block Work Abutting Structural Concrete:
- Where block work abuts structural concrete columns or walls and the like it shall be tied to the concrete with bitumen coated steel ties at 225 mm vertical centers. The ties shall be 50 X 3 X 600 mm girth once bent, one end shall be securely short filed to concrete and the other and solidly built into the block work, unless otherwise specified.
Reinforced Block Work:
- Where specified on the drawings walls shall be reinforced with horizontal joints reinforcement at the vertical intervals specified.
- The width of joints reinforcement will be that recommended by the manufacturer for each thickness of wall. Method Sequence for Block Masonry Work
- The joints reinforcement shall be completely bedded in the mortar and lapped at least 75 mm at joints in the length. At corners the joints reinforcement shall be cut neatly and butted together but not lapped.
Damp Proof Course and Treatments:
- Check for the requirement of DPC as per approved drawings. If DPC is required it shall be laid horizontally in external and internal walls at ground floor level in positions indicated on the drawings. Method Sequence for Block Masonry Work
- Damp-proof courses shall be laid horizontally in external walls at the last roof level and above openings. Vertical damp-proof courses shall be built into external cavity walls at jambs of openings and in the positions indicated on the drawings.
- Horizontal damp- proof courses shall be laid on a continuous bed of cement and sand (1:3) mortar and lapped minimum 150mm at joints in the length and lapped the full width of the wall at corners and passing. Work Procedure for Masonry
- All concealed wall surfaces below DPC level shall be painted with two coats bitumen paint and enclosed in minimum 1000 gauge polythene sheet membrane, the polythene sheet measure shall be tightly dressed up against the wall face and turned over the top of the block work for a width of alt least 50mm under damp-proof courses internally and on the wall courses immediately below the finished ground level externally. The polythene sheet membrane shall lap a minimum 100mm at all joints.
Protection to Block Work:
- Block Work shall be protected from damage by wet weather with QP approval coverings extending down both sides of exposed walls.
- All work shall be protected against rapid drying out by an approved method.
- Necessary steps to protect work to prevent damage by the building operations
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 lanyard. The area where the block work activities are in progress will be barricaded.
- Inspection Reports
- Mortar test certificate
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