Tools, Equipment and Materials for Blocklaying and Concreting
This domain tests identification, correct use, care and, above all, judgement about whether a tool or material is fit for the job. Expect picture-free descriptions (“a trowel with a 250–280 mm blade used for…”) and short specification questions on sand, cement and blocks.
Hand tools and their jobs
- Bricklayer’s trowel, 250–280 mm blade: spreading and cutting mortar.
- Pointing trowel: filling and finishing joints.
- Club hammer (2–4 lb) with bolster: cutting and trimming blocks.
- Spirit level, 600 mm for courses and 1.2 m for longer runs; plumb bob and line for verticality.
- Line and pins, jointers, hawk, wooden float (floating) and steel trowel (final finish), straight edge, gauge rod, builder’s square.
- Wheelbarrow, head pan, shovel, pickaxe, rammer, mixing board.
Plant
Site mixers are rated in bag batches (a typical tilting-drum mixer takes a one- or two-bag batch). Also: poker vibrator, plate compactor, block-moulding machine, block cutter, bar bender and cutter, and a water hose used as a water level.
Materials and specification
- Cement: 50 kg bags of 42.5R or 32.5 (pozzolana). Store on pallets 150 mm off the ground, no more than 8–10 bags high, oldest used first, and use within about three months. Reject lumpy or caked cement.
- Sand: sharp, clean, well graded, silt content not more than about 5% for good mortar and concrete.
- Coarse aggregate: clean 20 mm crushed stone, graded, free of clay and organic matter.
- Water: potable, free of oil, salt and organic matter.
- Sandcrete blocks: 450 × 225 × 150 mm for load-bearing walls, 450 × 225 × 100 mm for non-load-bearing partitions; use blocks at least 7 days old (28 days for full strength).
Worked example
A field silt test on a sand sample: 50 mm of sand in a measuring cylinder, water added to the 100 mm mark, shaken and left to settle for one hour. The silt layer measures 3 mm, so silt = 3/50 × 100 = 6%. The 5% limit is exceeded, so the sand is rejected or washed before use. Reasoning: silt coats the grains, raises the water demand and weakens the hardened mortar, so appearance alone is not enough evidence.
Traps that cost marks
Choosing cement by colour or brand rather than class; forgetting that a bag is 50 kg when converting to cubic metres; ignoring bulking of damp sand in volume batching; describing a tool without saying what it does; forgetting tool care - trowels cleaned and oiled, levels wiped dry, hoses drained.