Glossary of construction terms

Definitions

Adiabatic check

A verification under IEC 60364-4-43 that the energy let through by a protective device during a short circuit does not exceed the thermal withstand of the cable conductor, expressed as I squared t less than or equal to k squared S squared.

Admixture

A chemical added to a concrete or mortar mix in small quantity to modify one or more properties of the fresh or hardened state. Common admixtures include plasticisers, superplasticisers, retarders, accelerators, air-entrainers and waterproofing admixtures, covered under IS 9103 and ASTM C494.

Aggregate

The granular material, typically sand or crushed stone, that forms the bulk of a concrete or mortar mix and provides the structural skeleton bound by the cement paste. Covered under IS 383 for concrete aggregate.

Alkali-silica reaction

A chemical reaction between alkaline pore fluid in hardened concrete and reactive silica in certain aggregates, causing expansion and cracking over years. Mitigated by low-alkali cement, blended cements with fly ash or slag, and petrographic screening of aggregate.

Anchorage length

The length of rebar embedded beyond a point of no tension, required to develop the design stress in the bar without slip. Calculated per IS 456 Clause 26.2 and ACI 318 Chapter 25.

Arbitration

A private dispute-resolution process used in commercial contracts including supply contracts. See the delivery and logistics article for standard clauses.

Areametro footprint

Obsolete term; see service footprint.

Bar bending schedule

A tabular document prepared by the structural consultant or the cut-and-bend service that lists every rebar in a structure with its shape, length, diameter and quantity, used as the basis for procurement and cutting.

Batching

The process of measuring the constituent materials of a concrete or mortar mix by weight or volume before mixing. Weight batching is preferred over volume batching for structural work.

Binding wire

Annealed mild steel wire, typically 18 SWG, used to tie rebar intersections in a reinforcement cage so that the bars hold position during concrete placement. Specified under IS 280.

Blaine fineness

A measure of the specific surface area of cement particles in square metres per kilogram, determined by the air-permeability method under IS 4031 Part 2. A higher Blaine indicates a finer cement with faster early strength gain.

BOQ

Bill of quantities: a structured list of work items and materials with quantities, used to price a construction tender. See the procurement checklist article for the BOQ-to-PO workflow.

Breaking capacity

The maximum prospective short-circuit current that a protective device can safely interrupt, expressed in kiloamperes. For domestic MCBs under IEC 60898, the standard values are 6 kA and 10 kA.

Carbonation

The reaction of carbon dioxide in air with calcium hydroxide in hardened concrete, lowering the pore-fluid pH and eventually allowing embedded rebar to corrode. Mitigated by adequate cover, dense concrete and low water-cement ratio.

Cement paste

The binding phase of a concrete or mortar mix, consisting of cement and water before hydration and of hydrated calcium silicates and aluminates after hydration.

Characteristic strength

The strength value below which not more than five percent of test results are expected to fall. For concrete, expressed as the grade designation such as M30 meaning 30 N per square millimetre characteristic cube strength at twenty-eight days.

Chloride ingress

The penetration of chloride ions into hardened concrete from external sources such as seawater, de-icing salts or contaminated aggregate, eventually depassivating embedded rebar and initiating corrosion.

Class B lap

A tension lap splice in rebar detailing under ACI 318, equal to 1.3 times the tension development length, used where more than fifty percent of bars are lapped at one location.

CM/L number

A certification mark licence number issued by the Bureau of Indian Standards to manufacturers authorised to apply the BIS standard mark, printed on every bag of cement or bundle tag of TMT steel.

Cover

The minimum concrete thickness between the nearest concrete surface and the outermost rebar, required to protect the rebar from corrosion and to provide fire resistance. Specified in IS 456 Table 16 by exposure class.

CPVC

Chlorinated polyvinyl chloride, a plastic pipe material used for hot and cold water supply, specified under ASTM F441 and F442 with solvent-cement joints under ASTM F493.

CRS rebar

Corrosion-resistant steel rebar, a TMT variant with specific alloying elements and tighter chemistry limits giving improved resistance to chloride-induced corrosion. Specified by manufacturers under proprietary designations cross-referenced to IS 1786.

Curing compound

A liquid applied to freshly finished concrete to form a membrane that retards moisture loss during the curing period. Covered under ASTM C309.

Curve B, C, D

MCB trip-curve classifications under IEC 60898-1, defining the instantaneous trip range as a multiple of the rated current: 3-5 times for curve B, 5-10 times for curve C, and 10-20 times for curve D.

DCOF

Dynamic coefficient of friction, a slip-resistance measure for tile surfaces under ANSI A326.3. Values at or above 0.42 are classified as suitable for level interior wet areas.

Deformed bar

A rebar with transverse ribs rolled into the surface to improve the mechanical bond with surrounding concrete. Covered under IS 1786 for Indian TMT and ASTM A615 and A706 for American reinforcement.

Development length

The length of rebar required to develop the design stress by bond with surrounding concrete, calculated per IS 456 Clause 26.2.1 or ACI 318 Chapter 25.

Discrimination

The coordination between an upstream and a downstream protective device such that a fault downstream is cleared only by the downstream device, preserving supply to other circuits. Also called selectivity.

DPC

Damp proof course, a waterproof layer in a masonry wall at plinth level or under a window sill, preventing capillary rise of moisture.

Dry film thickness

The thickness of a paint or coating after the solvent has evaporated, measured under ASTM D7091 or ISO 2808.

Ductility

The capacity of a material to undergo plastic deformation before fracture, important for seismic resistance of rebar. Measured by the elongation at break under IS 1608.

E-way bill

An electronic document generated on the GST e-way bill portal before the movement of goods worth more than fifty thousand rupees, required to accompany the consignment.

Efflorescence

A white crystalline deposit on a masonry or plaster surface, caused by soluble salts migrating with water and depositing at the surface as the water evaporates.

Elongation

The percentage increase in gauge length of a tensile test specimen at fracture, a measure of ductility. Specified as a minimum of 16 percent for Fe 500 D under IS 1786.

Epoxy grout

A two-part grout based on epoxy resin and hardener, used in tile joints subject to chemical exposure or high hygiene standards. Specified under ANSI A118.3 and EN 13888.

EPS polystyrene

Expanded polystyrene, a rigid foam insulation material used in building envelopes and as void-fill in concrete construction.

Fe 500 D

A grade of TMT reinforcement under IS 1786 with minimum yield stress of 500 N per square millimetre, minimum elongation of 16 percent, and tightened chemistry limits on carbon, sulphur and phosphorus.

FGD gypsum

Flue-gas desulphurisation gypsum, a by-product of coal-fired power generation used as a cement retarder and in gypsum plasterboard manufacture.

Fly ash

The fine powder collected from the flue gases of a pulverised-coal power plant, used as a supplementary cementitious material in Portland Pozzolana Cement under IS 1489 Part 1 and as a concrete admixture under IS 3812 Part 1.

Formwork

The temporary moulds used to contain fresh concrete until it hardens sufficiently to be self-supporting. Covered under IS 14687 for plywood formwork and ACI 347 for formwork design.

GGBS

Ground granulated blast-furnace slag, a by-product of iron-making used as a supplementary cementitious material in Portland Slag Cement under IS 455 and as a concrete admixture under IS 16714.

Goods receipt note

A document signed by the buyer on delivery of a consignment, recording the quantity received, any damage observed and any specification deviations; forms part of the three-way match with the purchase order and the invoice.

Grade

A designation of material strength or quality, such as M20 for 20 N per square millimetre concrete or Fe 500 D for 500 N per square millimetre ductile rebar.

Grouting

The process of filling joints, cracks or voids with a cementitious or polymeric grout, used in tile-laying, post-tensioning and structural repair.

GSM

Grams per square metre, a mass-per-area measure used for hessian cloth, geotextiles and paper-backed membranes.

GST

Goods and Services Tax, the unified indirect tax in force in India since 2017, replacing excise, VAT, service tax and several other levies. Administered through the GST Network at gst.gov.in.

GSTIN

Goods and Services Tax Identification Number, a fifteen-character alphanumeric identifier assigned to every registered taxpayer under the GST regime in India.

Gypsum plaster

A plaster material based on calcium sulphate hemihydrate, used for internal wall and ceiling finishes in dry areas. Covered under IS 2547.

HDPE

High-density polyethylene, a plastic pipe material used for water supply, gas distribution and industrial applications, specified under ASTM D3035 and F714.

Hook

A bent end at a rebar anchorage, typically 90 degrees with a straight anchorage beyond or 180 degrees in a U shape, reducing the straight development length required.

HSN code

Harmonised System of Nomenclature code, an internationally standardised classification of traded goods, required on every GST invoice for commodity identification.

Hydration

The chemical reaction between cement and water that produces the calcium silicate hydrate gel binding the concrete mass, continuing for weeks after placement.

IEC

International Electrotechnical Commission, the standards body for electrical and electronic technologies at iec.ch.

IP rating

Ingress protection rating under IEC 60529, a two-digit classification of an enclosure protection against solids and liquids, such as IP54 for dust-protected and splash-proof.

IRN

Invoice Reference Number, a unique number generated by the Invoice Registration Portal under the Indian GST e-invoicing regime for invoices above a statutory turnover threshold.

IS 1786

The Bureau of Indian Standards specification for high-strength deformed steel bars and wires for concrete reinforcement, covering grades Fe 500, Fe 500 D, Fe 550 D and others.

IS 456

The Bureau of Indian Standards code of practice for plain and reinforced concrete, covering design, materials, workmanship and durability.

Lap length

The overlap length between two rebars at a tension splice, typically 1.3 times the development length for a Class B lap under ACI 318.

Laticrete

A brand of tile adhesives, grouts and waterproofing products manufactured by MYK Laticrete in India under licence from Laticrete International.

LED driver

An electronic power supply that converts the alternating-current mains to a regulated direct-current output suitable for driving light-emitting diodes. Produces pulsating DC leakage that requires a Type A or Type F RCCB.

LLP

Limited Liability Partnership, a business entity form under the Limited Liability Partnership Act 2008 in India, combining features of a partnership and a private limited company.

LLPIN

Limited Liability Partnership Identification Number, the unique identifier assigned to every registered LLP by the Ministry of Corporate Affairs; Sumum Traders LLP holds LLPIN AAE-3987.

MCB

Miniature circuit breaker, a resettable over-current and short-circuit protective device for low-voltage circuits, specified under IEC 60898-1.

Mix design

The process of selecting the proportions of cement, water, aggregates and admixtures to meet the performance requirements of a concrete mix. Covered under IS 10262 and ACI 211.

Mortar

A bonding agent made from cement or lime, sand and water, used to bed masonry units and to apply plaster finishes.

NABL

National Accreditation Board for Testing and Calibration Laboratories, the Indian accreditation body for laboratory competence.

NBC

National Building Code of India, the comprehensive building regulation document published by the Bureau of Indian Standards as SP 7.

OPC

Ordinary Portland Cement, the general-purpose Portland cement specified under IS 269 with grade designations 33, 43 and 53.

Pozzolana

A siliceous or siliceous-and-aluminous material that reacts chemically with calcium hydroxide released by cement hydration to form additional calcium silicate hydrate. Fly ash is the most common pozzolana in Indian practice.

PPC

Portland Pozzolana Cement, a blended cement containing 15 to 35 percent fly ash or other pozzolana, specified under IS 1489 Part 1.

PPR

Polypropylene random copolymer, a plastic pipe material used for hot and cold water supply with heat-fusion joints, specified under DIN 8077 and 8078.

Proforma invoice

A pre-transaction document issued by the seller to confirm the terms of a proposed sale; not a statutory document and does not create a GST liability.

PSC

Portland Slag Cement, a blended cement containing 25 to 70 percent ground granulated blast-furnace slag, specified under IS 455.

Purchase order

A formal buyer document that authorises a supplier to deliver specified goods at specified prices and terms, forming a contractual instrument.

PVC

Polyvinyl chloride, a plastic pipe material used for cold-water supply, drainage and agricultural irrigation, specified under ASTM D1785 and IS 13592.

RCBO

Residual current circuit breaker with over-current protection, combining the functions of an MCB and an RCCB in a single device, specified under IEC 61009-1.

RCCB

Residual current circuit breaker, a device that disconnects a circuit when it detects current imbalance between phase and neutral above a rated sensitivity, specified under IEC 61008-1.

Ready-mix concrete

Concrete batched at a central plant and delivered to site in transit mixers, specified under IS 4926 and ASTM C94.

Rebar

Reinforcing bar, the steel reinforcement embedded in concrete to carry tensile stresses; see Fe 500 D and TMT.

Rolling marks

Embossed marks on a TMT bar surface showing the manufacturer identifier, grade and often the cast number, repeated every metre or so.

Service footprint

The geographic area served by a supplier on a regular basis; for Sumum Traders LLP this is twenty-six South Indian cities plus the Kyathsandra home base.

Setting time

The period from addition of water to cement at which a specified needle penetration is achieved, divided into initial and final setting times under IS 4031 Part 5.

Slump

A measure of the consistency of fresh concrete, determined by the vertical settlement of a conical concrete sample when the cone is lifted, under IS 1199 and ASTM C143.

Slump retention

The ability of a fresh concrete mix to maintain workability over time, particularly important for ready-mix concrete with long transit times.

Soundness

The volume stability of a hardened cement, measured by the Le Chatelier expansion test under IS 4031 Part 3, with a maximum limit of 10 millimetres for ordinary cements.

SPD

Surge protective device, a component installed in an electrical installation to divert transient over-voltages to earth, specified under IEC 61643-11 in Type 1, Type 2 and Type 3 classifications.

Splice

A connection between two rebar lengths by lap, mechanical coupler or weld, designed to transfer the design force from one bar to the next.

Stirrup

A closed loop of rebar, typically 8 to 10 millimetres in diameter, wrapped around the longitudinal bars of a beam or column to provide shear resistance and confinement.

SWR

Single-stack rainwater, soil, waste and rainwater combined drainage system, a non-pressure uPVC pipe system for above-ground drainage.

Tax invoice

The statutory GST document issued by a supplier on completion of a taxable supply, triggering the GST liability for the supplier and the input tax credit for the buyer.

Tile adhesive

A cement-based or polymer-based adhesive used to bond tiles to substrates, classified under IS 15477 and EN 12004 as C1, C2 or reaction-resin adhesives with optional suffixes for deformability, open time and slip resistance.

TMT

Thermo-mechanically treated, a manufacturing process for reinforcement bar in which a hot-rolled bar is rapidly water-quenched to produce a hard martensitic rim over a softer ductile core, giving high yield strength with preserved ductility.

Trip curve

The time-current characteristic of a circuit breaker, defining how quickly the breaker trips at various overcurrent levels. For residential MCBs, see curve B, C, D.

Type A RCCB

A residual current circuit breaker that senses sinusoidal AC leakage and pulsating DC leakage up to 6 milliamperes, required for modern residential circuits with electronic loads.

Type B RCCB

A residual current circuit breaker that senses smooth DC residual currents in addition to AC and pulsating DC, required for three-phase frequency converters, DC-side EV charging and transformerless PV inverters.

uPVC

Unplasticised polyvinyl chloride, a rigid plastic pipe material used for cold-water supply, soil and waste drainage and window profiles, specified under IS 4985 and ASTM D1785.

Vitrified tile

A ceramic tile with low water absorption, typically below 0.5 percent under ISO 10545-3, classified as group BIa under ISO 13006.

VOC

Volatile organic compound, a class of organic chemicals that evaporate at room temperature from paints, adhesives and sealants; limited by regulation under the EU Directive 2004/42/EC and US EPA Method 24.

Wall putty

A fine-particle filler applied to a plastered wall to produce a smooth surface for painting, based on white cement or acrylic binders.

Water-cement ratio

The ratio by weight of water to cement in a concrete or mortar mix, the single strongest determinant of hardened-concrete strength and durability.

Welded wire mesh

A sheet or roll of orthogonal wires welded at intersections, used as reinforcement in slabs, walls and floors. Specified under IS 1566 and ASTM A1064.

White cement

A low-iron Portland cement with L-value above 85, used for decorative finishes, tile joint filler and as a base for wall putty. Specified under IS 8042.

Yield stress

The stress in a material at which plastic deformation begins, measured as the 0.2 percent proof stress for steels without a clear yield point. For Fe 500 D rebar the minimum is 500 N per square millimetre.

South India service footprint