Tamil Nadu HSE First Year Basic Civil Engineering key terms

The branch of engineering that plans, designs, builds and maintains fixed structures such as roads, bridges, dams, buildings and water systems for public use and safety.

The basic physical facilities a community needs to function, including roads, bridges, water supply lines, drainage, power structures and public buildings, usually funded and owned publicly.

The technique of measuring horizontal and vertical distances and angles on the ground to fix the position of points and prepare maps, plans and sections for engineering works.

The surveying operation of finding the relative heights of points on or below the earth's surface, usually by reading a graduated staff through a levelling instrument set on a tripod.

A permanent, clearly marked point whose elevation above mean sea level is already known and recorded, used as the starting reference for levelling work in an area.

The height of a point expressed with reference to a chosen datum, usually mean sea level, obtained by adding or subtracting staff readings from a known benchmark level.

An imaginary line on a map joining all points on the ground that have the same elevation, so that closely spaced contours show steep slopes and widely spaced ones show gentle ground.

The constant vertical height difference between two successive contour lines on a map; a small interval suits flat ground needing detail, a large interval suits steep hilly terrain.

The horizontal angle measured at a survey station between a reference direction, usually magnetic north, and the line to another station, stated in degrees clockwise.

A method of surveying in which only linear measurements are taken in the field with a chain or tape, the area being divided into triangles whose sides are measured directly.

A rectangular building unit made from clay moulded and burnt in a kiln, or from sand-lime or concrete, used in walls and known by its standard size and compressive strength.

A plastic mixture of cement or lime with fine aggregate and water, spread between bricks or stones to bind them into a single strong mass and to fill the joints.

Construction work in which individual units such as bricks, stones or blocks are laid in courses and bonded together with mortar to form walls, piers and other load-bearing elements.

A horizontal structural member, of wood, stone, brick or reinforced concrete, placed across the top of a door or window opening to carry the wall load above it.

The lower projecting portion of a wall or column just above ground level, which raises the floor above damp ground and protects the building from surface water.

A continuous waterproof layer of bitumen, plastic sheet or dense cement mortar laid across a wall near ground level to stop moisture rising into the walls by capillary action.

A whitish powdery deposit of soluble salts that appears on the surface of bricks or plaster when moisture evaporates, indicating dampness and salt in the materials.

The lowest part of a structure, built below ground to transmit the total load of the building safely to the soil without excessive settlement or failure of the supporting strata.

The maximum pressure the soil beneath a foundation can safely carry without shear failure or settlement that would damage the structure above it.

The internal resisting force developed per unit area of a material when it is subjected to an external load, expressed in newtons per square millimetre or similar units.

The deformation of a material expressed as the change in length divided by the original length; it is a pure ratio and therefore has no units.

The ratio of direct stress to the corresponding strain within the elastic limit of a material, showing how stiff it is; steel has a much higher value than timber.

The algebraic sum of the moments of all forces acting on one side of a section of a beam, taken about that section; it produces bending and tensile or compressive stresses.

At any section of a beam, the algebraic sum of the vertical forces acting on one side of that section, tending to slide one part of the beam past the other.

A horizontal structural member supported at its ends or at intermediate points and carrying transverse loads, mainly by developing bending and shear resistance along its length.

A finely ground calcined mixture of limestone and clay that, when mixed with water, sets and hardens into a strong binding material used in mortar and concrete.

A composite of cement, fine aggregate, coarse aggregate and water which sets into a stone-like mass, strong in compression but weak in tension unless reinforced.

The mass of water divided by the mass of cement in a concrete mix; a lower ratio gives stronger, denser concrete while too little water makes the mix unworkable.

The ease with which freshly mixed concrete can be placed, compacted and finished without segregation, commonly judged on site by the slump test.

A simple field test in which freshly mixed concrete is placed in a standard cone and the cone is lifted; the measured drop indicates the workability of the mix.

Concrete containing steel bars placed where tension occurs, so that the steel carries tension and the concrete carries compression, producing a strong economical composite member.

Keeping freshly placed concrete moist and at a suitable temperature for a period after casting so that cement hydration continues and the concrete reaches its intended strength.

The system of collecting, treating, storing and distributing safe water through pipes, pumps and tanks from a source to the taps of consumers in a town or building.

The cloudiness of water caused by suspended particles such as silt, clay and organic matter, measured in nephelometric units and removed by coagulation, settling and filtration.

Biochemical Oxygen Demand: the amount of dissolved oxygen consumed by micro-organisms breaking down organic matter in a water sample over five days at twenty degrees Celsius, in milligrams per litre.

An underground chamber in which domestic sewage is retained long enough for solids to settle and decompose anaerobically, with the clarified liquid flowing out to soak pits.

A fixture such as a water closet, wash basin, sink or floor trap connected to the drainage system to receive soil or waste water and discharge it through a water seal.

A surfaced public road built on a prepared subgrade with layers of pavement, designed to carry traffic safely and comfortably between towns and within cities.

A road structure of bituminous layers over granular base and sub-base, which transmits load to the subgrade gradually and bends slightly under traffic without cracking suddenly.

A road structure of cement concrete slabs resting on a base course, which carries wheel loads mainly by slab action and is stiff, durable and costly to construct.

The transverse slope given to the road surface at a horizontal curve, raising the outer edge above the inner one to balance centrifugal force and help vehicles turn safely.

The slight transverse slope given to a road surface from the centre towards the edges so that rain water drains off quickly and the pavement stays dry.