WBBSE Madhyamik Vocational Construction key terms

A broken piece of a brick, often used as a filler in concrete or for levelling courses. Full-sized bricks are preferred for face work because bats are weaker and less uniform.

The shallow indentation pressed into one face of a brick. It holds mortar and helps key the brick into the course, giving a stronger bond than a plain flat face.

A whitish powdery deposit that appears on masonry surfaces when soluble salts in bricks or mortar migrate to the surface and crystallise. It signals poor-quality materials or dampness and should be brushed off and investigated.

The increase in volume of damp sand because water films push grains apart. It makes loose sand measure larger than its dry volume, so volume batching must allow for moisture to avoid short mixes.

The proportion of cement, fine aggregate and coarse aggregate in a concrete mix, written in that order, such as 1:2:4. A richer mix means more cement and higher strength and cost.

The mass of water divided by the mass of cement in a concrete mix. Extra water makes concrete easier to place but lowers strength and durability, so the ratio is kept as low as workability allows.

A simple site test that measures how far a freshly filled concrete cone settles when the mould is lifted. It indicates workability or consistency, not strength, and is done before placing concrete.

Keeping newly placed concrete or masonry moist for a set period so cement hydrates fully. Proper curing raises strength and reduces shrinkage cracks; it usually starts soon after setting and lasts days.

A paste of cement or lime, sand and water used to join masonry units and fill joints. It sets hard to bond bricks or blocks and also spreads load between them in the wall.

A binding material made by burning limestone, used in mortar and plaster. It gives good workability and flexibility but hardens slowly and is weaker than cement in wet conditions.

A brick wall bond with alternating courses of stretchers and headers. It is strong and has no continuous vertical joint through the wall, but it needs more facing bricks and is slower to lay.

The corner brick or stone of a wall, or the corner angle itself. Quoins are laid carefully to true lines and plumb because they set the level and alignment for the whole wall.

The lower projecting part of a wall or column, just above ground level. It protects the base from rain splash and damp and gives the building a visual base line.

A continuous layer of impervious material laid in a wall near ground level to stop moisture rising by capillary action. It must be unbroken and joined to the damp-proof membrane of the floor.

A horizontal beam of wood, stone, brick or reinforced concrete spanning an opening to carry the wall above a door or window. It transfers that load to the masonry on either side.

A small projecting slab or roof over a door, window or verandah that throws off rain and gives shade. It is usually cast in reinforced concrete and sloped outward slightly.

The length of a beam, slab or lintel that rests on a support such as a wall or column. Enough bearing must be provided so the load spreads safely without crushing the supporting material.

A horizontal structural member that carries loads across a span and transfers them to columns or walls. It resists bending, so its depth and reinforcement are chosen for the span and load.

Temporary moulds of timber, plywood or steel built to hold fresh concrete in shape until it hardens. Formwork must be strong, tight and true, and is stripped after curing.

A pointed weight hung on a string to show a true vertical line. It is used to check that walls, columns and formwork are upright and that points are directly above one another.

A tool with a sealed glass tube containing liquid and a bubble. When the bubble sits between the marks, the surface is truly horizontal or vertical, so it is used for levelling and checking.

A flat steel hand tool with a handle used for spreading and smoothing mortar or plaster. Different shapes suit laying bricks, floating plaster or finishing edges.

A narrow straight wooden or metal straightedge with a plumb line, used to check the verticality of walls and corners. It shows whether a wall leans and by how much.

A small spirit level with hooks that hangs from a masonry line to check that the line is horizontal. It lets a mason keep long courses level without a full straightedge.

A fixed point of known reduced level, often a brass plate or marked stone, used as a reference for levelling. Survey levels are measured from or transferred from a bench mark.

The height of a point above or below a chosen datum, usually mean sea level. It is calculated from staff readings and the instrument height during levelling work.

A surveying instrument with a fixed telescope held level by a spirit level, used mainly for levelling and height work. It is simple and sturdy but cannot measure horizontal angles like a theodolite.

A graduated rod held upright on a point so the level instrument can read its height. The reading, together with the instrument height, gives the reduced level of that point.

The first staff reading taken on a point of known level after setting up the instrument. It establishes the height of the instrument and is the reference for all following readings.

A staff reading taken on a point whose level is to be found, usually the last reading before moving the instrument. It is subtracted from the instrument height to get that point's level.

Marking the exact position, lines and levels of a building or structure on the ground before excavation. It uses pegs, strings and right-angle methods so the work is built in the right place.

A setting-out technique for a right angle using a triangle with sides in the ratio 3, 4 and 5. When the two shorter sides are set, the longest side confirms a true 90-degree corner.

A line drawn through the middle of a wall, column or structural member. In setting out and estimating, dimensions are often measured between centre lines rather than faces.

The ratio between a distance on a drawing and the real distance it represents, such as 1:50. The scale chosen must suit the size of the drawing sheet and the detail needed.

A drawing that shows a building viewed from above, cut at a chosen height, with walls, openings and layout. It gives lengths and positions but not heights, which appear on elevations and sections.

A drawing of one outside face of a building, showing its height, levels and features as seen straight on. It is used to show door and window positions and roof shape.

A drawing that shows a building as if cut through by a vertical plane, revealing internal construction and heights. It is used to show floor levels, foundations and slab and roof build-ups.

Gear worn to protect a worker from site hazards, such as helmet, boots, gloves, goggles and high-visibility vest. It is the last line of defence and must be checked, fitted and used correctly.

A hard hat worn on site to protect the head from falling objects and knocks. It must be worn where overhead work happens and replaced if cracked or past its service life.

A temporary framework of tubes, boards and supports giving workers a safe platform at height. It must be properly braced, tied and founded so it does not overturn or collapse.

The area covered by a building measured outside its plinth, including external walls but excluding projections such as balconies. It is the basis for rough cost estimates in many building works.

An estimate prepared by measuring each item of work separately and multiplying its quantity by a rate. It is accurate but slow, and needs drawings, specifications and a bill of quantities.

A priced schedule listing each work item with its quantity, description and unit, prepared from drawings. It is used for tendering and for measuring and valuing work as it proceeds.

The process of measuring quantities of work from drawings and entering them in a measurement sheet. Quantities are taken item by item in the order of the estimate or bill.

The cost of one unit of a work item, such as per cubic metre of concrete or per square metre of plaster. It combines labour, material, plant and overheads and is multiplied by the quantity.

Measuring concrete or mortar ingredients by loose volume, often with boxes or gauge pans, instead of by weight. It is quick on small sites but less accurate because of bulking and compaction.