CTVET Ghana Certificate II - Blocklaying & Concreting key terms

Items worn by a worker to reduce the risk of injury, such as a hard hat, safety boots, goggles, gloves, dust mask and high-visibility vest. It is the last line of defence after hazards are removed or controlled.

Any condition, substance or activity on site with the potential to cause harm, injury, illness or damage to property. Examples include open excavations, unstable scaffolding, silica dust and live electrical cables.

A careful examination of what on site could harm people and a decision on how serious the risk is and what controls are needed. It is recorded and reviewed as work changes.

A short, informal safety briefing given to the work gang at the start of a shift or task, covering the specific hazards of that day's work and the precautions to take. Attendance is usually recorded.

The maximum load a sling, scaffold platform, hoist or lifting accessory is designed to carry safely under normal conditions. It is marked on the equipment and must never be exceeded.

A temporary working platform with standards, ledgers, transoms, boards and guardrails, erected so that blocklayers can work safely at height. It must be erected, inspected and tagged by competent persons.

A document supplied with a chemical product such as cement, lime, admixture or curing compound, listing its hazards, safe handling, first-aid measures and storage requirements. Workers should read it before first use.

A tool containing sealed glass vials partly filled with liquid and an air bubble; the bubble centred between marks shows that a surface is truly horizontal or vertical. Long levels are used for courses and short ones for small work.

A narrow straight edge with a plumb line or vial used to check that a wall face is truly vertical. It is held against the work and the gap or lean is observed along its length.

A wide, chisel-like steel blade with a handle, used with a club hammer for cutting bricks and blocks to size. The blade is placed on the cut line and struck sharply on both faces.

A short-handled hammer with a heavy double-faced head, used to drive a bolster when cutting masonry and to tap blocks into line. Its weight gives the controlled blow needed without excessive swing.

A flat steel blade with a wooden or plastic handle, used to pick up mortar, spread beds and joints, and tap bricks or blocks into position. The pointed heel is used for buttering and trimming mortar.

A flat board, usually about one metre square, on which mortar is delivered and kept workable during bricklaying. It is raised off the ground to prevent contamination and to save the mason's back.

The process of transferring the building's position, size and levels from the drawings onto the ground using pegs, lines and profiles, so that excavation and construction start in the right place.

A fixed reference point or level from which other heights and depths on a project are measured. It may be a benchmark, a mark on a permanent structure or a site peg, and must not be disturbed.

A line marked on the ground, fixed by pegs and string, defining the outer face or centre line of a wall or the boundary within which the structure must be built.

A pair of horizontal boards fixed to stakes outside the corners of the building, carrying nails that hold the building lines. Lines are stretched between profiles to control wall position and thickness.

A setting-out technique for producing a right angle using a triangle with sides in the ratio 3:4:5. Measuring 3 m, 4 m and 5 m along the lines confirms the corner is square.

A brickwork bond in which all bricks are laid lengthwise along the wall, with each course offset by half a brick so that vertical joints do not align. It is common in half-brick walls and blockwork.

A strong brickwork bond made of alternating courses of stretchers and headers. It gives good longitudinal strength and is often used for walls one brick thick and above.

The horizontal layer of mortar on which a brick or block is laid. Its thickness, usually about 10 mm, must be even so that courses stay level and the wall carries load uniformly.

The vertical mortar joints between bricks or blocks in a course. They should be filled solid and aligned vertically from course to course unless the bond requires an offset.

The corner brick or block that is specially selected and laid to form a true, plumb and square corner. Quoins are built first and the rest of the wall is lined to them.

A bond made entirely of bricks laid with their short ends facing the wall face, giving a strong wall of one-brick thickness. It is often used for curved work and footings.

A finely ground powder that, when mixed with water, sets and hardens by chemical reaction and binds aggregates together. Ordinary Portland cement is the usual type on site.

A mixture of cement, fine aggregate, coarse aggregate and water that hardens into a stone-like mass. Its strength depends on the proportions used, the water-cement ratio and proper curing.

The mass or volume of water divided by the mass of cement in a mix. A lower ratio generally gives stronger, more durable concrete, but too little water makes the mix unworkable.

How easily a fresh concrete or mortar mix can be mixed, transported, placed and compacted without segregation. It is commonly judged by the slump test or by the feel of the mix.

A site test in which fresh concrete is placed in a standard cone, the cone is lifted, and the drop in height of the concrete is measured. It indicates workability and consistency, not strength.

The removal of trapped air from freshly placed concrete or mortar by vibration, tamping or rodding, so that it fills the formwork and surrounds reinforcement. Poor compaction leaves voids and weakens the work.

The separation of the ingredients of a concrete or mortar mix, for example coarse aggregate settling apart from the paste. It is caused by over-wet mixes, long drops or excessive handling.

Keeping newly placed concrete or mortar moist and at a suitable temperature for a period after placing, so that the cement hydrates fully and the required strength and durability develop. It may use water, plastic sheeting or curing compound.

Steel bars or mesh placed in concrete to resist tensile and shear forces that plain concrete cannot carry. It must be clean, correctly positioned and surrounded by enough concrete cover.

The thickness of concrete between the outer surface of the reinforcement and the nearest concrete face. Adequate cover protects the steel from corrosion and fire and ensures the bars bond to the concrete.

The temporary mould of timber, plywood or metal that holds fresh concrete in shape and position until it has set sufficiently. It must be strong, tight against leakage and easy to strike without damaging the concrete.

The ratio between a distance on a drawing and the real distance it represents, for example 1:50. A candidate must choose the correct scale to read or set out dimensions accurately.

A priced document listing the work items, their descriptions and measured quantities, prepared from the drawings so that contractors can price a project and be paid for work done.

The process of measuring quantities of work from drawings and specifications, such as cubic metres of concrete or square metres of blockwork, and entering them in a dimension sheet for pricing.

A precast masonry unit, commonly of concrete or clay, larger than a brick and used for walls. Its size, density and strength class must match the drawing and structural requirements.