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Mixing, Laying, Compaction, Curing

IS 6461 (Part 7) — Cement Concrete: Glossary of Terms (First Revision, October 2024) · 2024 definitions.

Part 6 Part 8Definitions quoted verbatim from the BIS standard

Accessories Cl 3.1: Those items other than frames, b races, or post shores used to facilitate the construction of scaffold and shoring.
Adiabatic Curing Cl 3.2: The maintenance of adiabatic con ditions in concrete or mortar during the curing period.
Advancing Slope Grouting Cl 3.3: A method of groutin g by which the front of a mass of grout is caused to move horizontally through preplaced aggregate by use of a suitable grout injection sequence.
Advancing Slope Method Cl 3.4: A method of placing concrete as in tunnel linings in which the face of the fresh concrete is not vertical and moves forward as concrete is placed.
Agglomeration Cl 3.5: Gathering into a ball or mass.
Aggregate Interlock Cl 3.6: The projection of aggregate particles or portions of aggregate particles from one side of a joint or crack in concrete into recesses in the other side of such joint or crack so as to effect load transfer in compression and shear, and maintain mutual alignment.
Agitating Speed Cl 3.7: The rate of rotation of the drum or blades of a truck mixer or other device when used for agitation of mixed concrete.
Air Cl 3.9: Water Jet — A high-velocity jet of air and water mixed at the nozzle, used in clean-up of surfaces of rock or concrete such as horizontal construction joints.
Alignment Wire Cl 3.10: Small-gage high-strength steel wire u sed to establish line and grade as in shotcrete work; also called alignment wire or screed wire.
Alternate Lane Construction Cl 3.11: A method of constru cting concrete roads, runways, or other paved areas, in which alternate lanes are placed and allowed to harden before the remaining intermediate lanes are placed.
Amount of Mixing Cl 3.12: The designation of extent of mixer action employed in combining the ingredients for concrete or mortar; in the case of stationary mixers, the mixing time; in the case of truck mixers, the number of revolutions of the drum IS 6461 (Part 7) : 2024 1 To access Indian Standards click on the link below: https://www.services.bis.gov.in/php/BIS_2.0/bisconnect/knowyourstandards/Indian_standards/isdetails/ or blades at mixing speed after the intermingling of the cement with water and aggregates.
Amplitude of Vibration Cl 3.13: The maximum displacement from the mean position in connection with vibration.
Anchor Bolt Cl 3.14: A bolt with the threaded portion projecting from a structure, generally used to hold the frame of a building secure against wind load or a machine against the forces of vibration; known also as hold-down bolt and foundation bolt.
Atmospheric Steam Curing Cl 3.15: Steam curing of concrete products or cement at atmospheric pressure, usually at maximum ambient temperature between 40 °C to 95 °C.
Autoclave Cl 3.16: A pressure vessel in which an environment of steam at high pressure may be produced; used in the curing of concrete products and in the testing of hydraulic cement for soundness.
Autoclave Curing Cl 3.17: Steam curing of concrete products, sandlime brick, asbestos cement products, hydrous calcium silicate insulation products, or cement in an autoclave at maximum ambient temperatures generally between 170 °C and 215 °C.
Autoclave Cycle Cl 3.18: The time interval between the start of the temperature -rise period and the end of the blowdown period; also, a schedule of the time and temperature -pressure conditions of periods which make up the cycle.
Autogenous Healing Cl 3.21: A natural process of closing and filling of cracks in concrete or mortar when the concrete or mortar is kept damp.
Autogenous Volume Change Cl 3.22: Change in volume produced by continued hydration of cement exclusive of effects of external forces or change of the water content or temperature.
Back Plastering Cl 3.23: Plaster applied to one face of a lath system following application and subsequent hardening of plaster applied to the opposite face.
Barliner (Crazy) Cl 3.24: A type of terrazzo topping using small and large pieces of marble paving, usually with a standard terrazzo matrix between pieces.
Base Cl 3.25: A subfloor slab or ‘working mat’ either previously placed and hardened or freshly placed, on which floor topping is placed in a later operation; also the underlying stratum on which a concrete, such as a pavement is placed.
Base Bed Cl 3.26: A preformed metal screed with perforated or expanded flanges to provide a ground for plaster and to separate areas of dissimilar materials.
Base Coat Cl 3.27: Any plaster coat or coats applied prior to applicable of the finish coat.
Base Plate Cl 3.28: A plate of metal or other approved material formerly placed under pavement joints and the adjacent slab ends to prevent the infiltration of soil and moisture, from the sides or bottom of the joint opening, also a device used to distribute vertical loads as for building columns or machinery.
Base Screed Cl 3.29: A preformed metal screed with perforated or expanded flanges to provide a ground for plaster and to separate areas of dissimilar materials.
Batch Cl 3.30: Quantity of concrete or mortar mixed at one time.
Batch Box Cl 3.31: Container of known volume used to measure constituents of a batch of concrete or mortar in proper proportions.
Batched Water Cl 3.32: The mixing water added by a batcher to a concrete or mortar mixture before or during the initial stages of mixing.
Batching Cl 3.33: Weighing or volumetrically measuring and introducing into the mixer the ingredients for a batch of concrete or mortar.
Beam Pocket Cl 3.34: Opening left in a vertical member in which a beam is to rest; also an opening in the column girder form where forms for an intersecting beam will be framed.
Bleeding Cl 3.35: The autogenous flow of mixing water within, or its emergence from newly placed concrete or mortar; caused by the settlement of the solid materials within the mass or drainage of mixing water; also called water gain.
Blinding Cl 3.36: The application of a layer of weak concrete or other suitable material to reduce surface voids, or to provide a clean dry working surface; also the filling or plugging of the openings in a screen or sieve by the material being separated.
Blistering Cl 3.37: The irregular raising of a thin layer at the surface of placed mortar or concrete during or soon after completion of the finishing IS 6461 (Part 7) : 2024 2 operation, or in the case of pipe after spinning; also bulging of the finish plaster coat as it separates and draws away from the base coat.
Blockout Cl 3.38: A space within a concrete structure under construction in which fresh concrete is not to be placed (also called core).
Blowdown Period Cl 3.39: Time taken to reduce pressure in an autoclave from maximum to atmospheric.
Board Butt Joint Cl 3.40: Shotcrete construction joint formed by sloping gunned surface to a 25 mm thick board laid flat.
Bolt Sle eve Cl 3.41: A tube surrounding a bolt in a concrete wall to prevent concrete from sticking to the bolt and acting as a spreader for the formwork.
Bond Breaker Cl 3.42: A material used to prevent adhesion of newly placed concrete and the substrate.
Bond Plaster Cl 3.43: A specially formulated gypsum plaster designed as first coat application over monolithic concrete.
Bonding Agent Cl 3.44: A substance applied to a suitable substrate to create a bond between it and a succeeding layer as between a subsurface and a terrazzo topping or a succeeding plaster application.
Bonding Layer Cl 3.45: A layer of mortar, usually 3 cm to 12 cm thick, which is spread on a moist and prepared, hardened concrete surface prior to placing fresh concrete.
Broom Finish Cl 3.46: The surface texture obtained by stroking a broom over freshly placed concrete.
Brown Coat Cl 3.47: The second coat in three -coat plaster application.
Brown Cut Cl 3.48: To complete application of basecoat plaster.
Build Cl 3.49: Up — Gunning of shotcrete in successive layers to form a thicker mass.
Bull Float Cl 3.50: A tool comprising a large, flat, rectangular piece of wood, aluminium, or magnesium usually 20 cm wide and 100 cm to 150 cm long, and a handle 1 m to 5 m in length used to smooth unformed surfaces of freshly placed concrete.
Burlap Cl 3.51: A coarse fabric of jute, hemp, or less commonly, flax, for use as a water -retaining covering in curing concrete surfaces.
Bush Cl 3.52: Hammer — A hammer having a serrated face, as rows of pyramidal points used to roughen or dress a surface; to finish a concrete surface; by application of a bush-hammer.
Bush Cl 3.53: Hammer Finish — A finish on concrete obtained by means of a bush-hammer.
Butt Joint Cl 3.54: A plain square joint between two members.
Buttress Cl 3.55: A projecting structure to support a wall or building.
Catalyst ( or Curing Agent or Promoter ) Cl 3.56: A substance that accelerates or causes a chemical reaction without itself being transformed by the reaction.
Catface Cl 3.57: Belmish or rough depression in the finish plaster coat caused by variations in the base coat thickness.
Cellular Construction Cl 3.58: A method of constructing concrete elements in which part of the interior concrete is replaced by voids.
Cellular Raft Cl 3.59: A raft in which the intersecting beams form a number of cells.
Cement Bacillus Cl 3.60: See 3.152.
Cement Content Cl 3.61: Quantity of cement contained in a unit volume of concrete or mortar, preferably expressed as weight.
Cement Gel Cl 3.63: The colloidal material that makes up the major portion of the porous mass of which mature hydrated cement paste is composed.
Cementation Process Cl 3.64: The process of injecting cement grout under pressure into certain types of ground (for example, gravel, fractured rock to solidify it).
Central Cl 3.65: Mixed Concrete — Concrete which is completely mixed in a stationary mixer from which it is transported to the delivery point.
Chalking Cl 3.66: Disintegration of coatings, such as a cement paint, manifested by the presence of a loose powder evolved from the paint at, or just beneath, the surface.
Chamfer Cl 3.67: A beveled corner which is formed in concrete work by placing a chamfer strip in the corner of the form. IS 6461 (Part 7) : 2024 3
Chamfer Strip Cl 3.68: Triangular or curved insert placed in an inside form corner to produce a rounded or flat chamfer; also called fillet, cant strip, skew back.
Charging Cl 3.69: Introducing, feeding, or loading materials into a concrete or mortar mixer, furnace , or other container or receptacle where they will be further treated or processed.
Checking Cl 3.70: Development of shallow cracks at closely spaced but irregular intervals on the surface of mortar or concrete.
Chipping Cl 3.71: Treatment of a hardened concrete surface by chiseling.
Chute Cl 3.72: A sloping trough or tube for conducting concrete, cement, aggregate, or other free flowing materials from a higher to a lower point.
Cleanup Cl 3.73: Treatment of horizontal construction joints to remove all surface material and contamination to a condition of cleanliness corresponding to that of a freshly broken surface of concrete.
Closed Cl 3.74: Circuit Grouting — Injection of grout into a hole intersecting fissures or voids which are to be filled at such volume and pressure that grout input to the hole is greater than the grout take of the surrounding formation, excess grout being returned to the pumping plant for recirculation.
Coat Cl 3.75: A film or layer as of paint or plaster applied in a single operation.
Coating Cl 3.76: Material applied to a surface by brushing, mopping, spraying, trowelling, etc, such as to preserve, protect, seal, or smooth the substrate.
Cold Joint Cl 3.77: A joint or discontinuity formed when a concrete surface hardens before the next batch is placed against it, characterized by poor bond unless necessary procedures are observed.
Compaction Cl 3.78: The process of inducing a closer pac king of the solid particles in freshly mixed concrete or mortar during placement by the reduction of the volume of voids, usually by vibration, centrifugation, tamping, or some combination of these actions; also applicable to similar manipulation of other cementitious mixtures, soils, aggregate, or the like (see also 3.88).
Composite Concrete Flexural Construction Cl 3.79: A precast concrete member and cast-in-place reinforced concrete so interconnected that the component elements act together as a flexural unit.
Composite Construction Cl 3.80: A type of construction made up of different materials, for example, concrete and structural steel, or of members produced by different methods, for example, in situ concrete and precast concrete.
Concrete, Dense Cl 3.81: Concrete containing a minimum number of voids.
Concrete, Fat Cl 3.82: A concrete containing a large proportion of mortar.
Concrete, Field Cl 3.83: Concrete delivered or mixed, placed, and cured on the job site.
Concrete, Green Cl 3.84: Concrete which has set but not appreciably hardened.
Concrete, In Situ (also Cast Cl 3.85: in-Place) — Concrete which is deposited in the place where it is required to harden as part of the structure, as opposed to precast concrete.
Concrete, Normal Cl 3.86: Weight — Concrete having a unit weight of approximately 2 400 kg/m 3 made with aggregates of normal weight.
Confined Concrete Cl 3.87: Concrete containing closely spaced special transverse reinforcement which is provided to restrain the concrete in directions perpendicular to the applied stresses.
Consolidation Cl 3.88: Compaction of freshly placed co ncrete or mortar to minimum practical volume, usually by vibration, centrifugation, tamping, or some combination of these, to mold it within forms or molds and around embedded parts and reinforcement, and to eliminate voids other than entrained air (see also 3.78).
Construction, Composite Cl 3.89: Construction consisting of cast -in-place reinforced concrete and members made of some other material so interconnected that the component elements act together as a unit.
Construction Joint Cl 3.90: The surface where two successive placements of concrete meet ( see also 3.199).
Construction Loads Cl 3.91: The loads to which a permanent or temporary structure is subjected during construction.
Contact Ceiling Cl 3.92: A ceiling which is secured in direct contact with the construction above without use of furring.
Contact Pressure Cl 3.93: Pressure acting at and perpendicular to the contact area between footing IS 6461 (Part 7) : 2024 4 and soil, produced by the weight of the footing and all forces acting on it.
Containment Grouting Cl 3.94: See 3.233.
Contraction Joint Cl 3.95: A plane, usually vertical, separating concrete in a structure or pavement, at a designed location such as to interfere least with performance of the structure, yet such as to prevent formation of objectionable shrinkage cracks elsewhere in the concrete.
Contraction Joint Grouting Cl 3.96: Injection of grout into contraction joints.
Control Factor Cl 3.97: The ratio of the minimum compressive strength to the average compressive strength.
Control Joint Cl 3.98: Formed, sawed, or tooled groove in a concrete structure to regulate the location and amount of cracking and separation resulting from the dimensional change of different parts of a structure so as to avoid the development of high stresses.
Core Cl 3.100: The soil material enclosed within a tubu lar pile after driving (it may be replaced with concrete). The mandrel used for driving casings for cast-in-place piles. Portion of a reinforced concrete column inside the centre line of the principal reinforcement. A cylindrical sample of hardened concrete or rock obtained by means of a core drill. The moulded open space in a concrete masonry units (see 3.38).
Cored Beam Cl 3.101: A beam whose cross-section is partially hollow, or a beam from which cored samples of concrete have been taken.
Coring Cl 3.102: The act of obtaining cores from concrete structures or rock foundations.
Cotton Mats Cl 3.103: Cotton-filled quilts fabricated for use as a water retaining covering in curing concrete surfaces.
Course Cl 3.104: A horizontal layer of concrete usually one of several making up a lift (see 3.198).
Cover Cl 3.105: In reinforced concrete, the least distance between the surface of the reinforcement and the outer surface of the concrete.
Craze Cracks Cl 3.106: Fine, random cracks or fissures caused by shrinkage which may appear in a surface of plaster, cement paste, mortar, or concrete.
Crazing Cl 3.107: The development of craze cracks; the pattern of craze cracks existing in a surface.
C/S Ratio Cl 3.108: The molar or weight ratio, whichever is specified, of calcium oxide to silicon dioxide; usually of binder materials cured in an autoclave.
Cumulative Batching Cl 3.109: Measuring more than one ingredient of a batch in the same container by bringin g the b atcher scale into balance at successive total weights as each ingredient is accumulated in the container.
Curing Cl 3.110: Maintenance of humidity and temperature of freshly placed concrete during some definite period following placing, casting, or finishing to assure satisfactory hydration of the cementitious materials and proper hardening of the concrete.
Curing Blanket Cl 3.111: A built -up covering of sacks, matting, hessian, straw, waterproof paper, or other suitable material placed over freshly finished concrete.
Curing Cycle Cl 3.112: See 3.18 and 3.307.
Curing Delay Cl 3.113: In steam curing of concrete products, the period between the completion of placement of concrete in molds and forms or forming of masonry units by machine and the application of steam.
Curing Kiln Cl 3.114: See 3.306.
Curing Membrane Cl 3.115: See 3.208.
Curling Cl 3.116: The distortion of an originally essentially linear or planer member into a curved shape such as the warping of a slab due to creep or differences in temperature or moisture content in the zones adjacent to its opposite faces.
Curtain Grouting Cl 3.117: Injection of grout into a subsurface formation in such a way as to create a zone of grouted material transverse to the direction of anticipated water flow.
Damp Proofing Cl 3.118: Treatment of concrete or mortar to retard the passage or absorption of water, or water vapour, either by application of a suitable coating to exposed surfaces, or by use of a suitable admixture or treated cement.
Dash Cl 3.119: Bond Coat — A thick slurry of Portland cement, sand and water dashed on surfaces with a paddle or brush to provide a base for subsequent Portland cement plaster coats. IS 6461 (Part 7) : 2024 5
D Cl 3.120: cracking — The progressive formation of a series of fine cracks at rather close intervals on a concrete surface often of random patterns, in highway slabs paralleling edges, joints, and cracks and curving across slab corners (also termed D-cracks and D-line cracks).
Decenter Cl 3.121: To lower or remove centering or shoring.
Deformed Metal Plate Cl 3.122: A metal plate with horizontal deformations or corrugations used in construction to form a vertical joint and provide a mechanical interlock between adjacent sections.
Delay Cl 3.123: See 3.113 and 3.249.
Deterioration Cl 3.125: See 3.129.
Diagonal Crack Cl 3.126: An inclined crack, usually at about 45 deg ree to the center line beginning at the tension surface of a concrete member.
Diagonal Cracking Cl 3.127: Development of diagonal cracks.
Direct Dumping Cl 3.128: Discharge of concrete directly into place from crane bucket or mixer.
Disintegration Cl 3.129: Deterioration into small fragments or particles due to any cause.
Distribution Cl 3.130: The movement of freshly mixed concrete toward the point of placement either by hand or motorized tools.
Divider Strips Cl 3.131: In terrazzo work, non - ferrous metal or plastic strips of different thicknesses usually 10 or 40 mm deep used to form panels in the topping.
D Cl 3.132: line Cracks — See 3.120.
Double Cl 3.133: Up — A method of plastering characterized by application in successive operations with no setting or drying time between coats.
Doughnut Cl 3.134: A large washer of any shape to increase bearing area of bolts and ties; also a round concrete spacer with hole in the centre to hold bars at the desired distance from the forms.
Dowel Cl 3.135: A steel bar, commonly a plain round steel bar, which extends into two adjoining portions of a concrete construction, as at a joint in a pavement slab, so as to connect the portions and transfer shear loads.
Dowel Deflection Cl 3.136: Deflection caused by the transverse load imposed on a dowel.
Dowel Lubricant Cl 3.137: Lubricating material applied to bars in expansion joints to reduce bond with the concrete and promote unrestrained longitudinal movement.
Drip Cl 3.138: A cut -out in the underside of a projecting piece of stone or concrete to prevent water from working back to a wall.
Dropchute Cl 3.139: A device used to confine or direct the flow of a falling stream of concrete. a) Articulated Dropchute — A dropchute consisting of a vertical succession of tapered metal cylinders which are so designed that the lower end of each cylinder fits into the upper end of the one below; and b) Flexible Dropchute — A dropchute consisting of a heavy, rubberized canvas tube.
Dry Cl 3.140: Batch Weight — The weight of the materials, excluding water used to make a batch of concrete.
Dry Mix Cl 3.141: A mixture containing little water in relation to its other components.
Dry Mixing Cl 3.142: Blending of the solid materials for mortar or concrete prior to adding the mixing water.
Dry Pack Cl 3.143: To forcibly ram a moist Portland-cement-aggregate mixture into a confined area; also the mixture so placed.
Dry Cl 3.144: Packed Concrete — A concrete mixture sufficiently dry to be consolidated only by heavy ramming.
Dry Shake Cl 3.145: See 3.217.
Dry Cl 3.146: Tamp Process — The placing of concrete or mortar by hammering or ramming a relatively dry mix into place.
Dry Topping Cl 3.147: See 3.217.
Dry Cl 3.148: Volume Measurement — Measurement of the ingredients of grout, mortar, or concrete by their bulk volume. IS 6461 (Part 7) : 2024 6
Duct Cl 3.149: A hole formed in a concrete member to accommodate a tendon for post-tensioning; a pipe or runway, for electric, telephone, or other utilities.
Dummy Joint Cl 3.150: See 3.172.
Dusting Cl 3.151: The development of a powdered material at the surface of hardened concrete.
Ettringite Cl 3.152: A mineral, high sulphate calcium sulphoaluminate (3CaO.Al 2O3.CaSO4.30- 32H2O); occurring naturally or formed by sulphate attack on mortar and concrete; designated as ‘cement bacillus’ in older literature.
Exfoliation Cl 3.153: Disintegration occurring by peeling off in successive layers; swelling up and opening into leaves or plates like a partly opened book.
Expansion Joint Cl 3.154: A separation between adjoining parts of a concrete structure which is provided to allow small relative movements, such as those caused by thermal changes to occur independently.
Exposed Cl 3.155: Aggregate Finish — A decorative finish for concrete work achieved by removing, generally before the concrete has fully hardened, the outer skin of mortar and exposing the coarse aggregate.
Faulting Cl 3.156: Differential vertical displacement of a slab or other member adjacement to a joint or crack.
Fin Cl 3.159: A narrow linear projection on a formed concrete surface, resulting from mortar flowing out between spaces in the formwork.
Finish Cl 3.160: The texture and smoothness of a surface after compacting and finishing operations have been performed.
Finish Coat Cl 3.161: Final thin coat of shotcrete preparatory to hand finishing; also exposed coat of plaster and stucco.
Finish Grinding Cl 3.162: The final grinding of clinker into cement, with calcium sulphate in the form of gypsum or anhydrite generally being added, the final grinding operation required for a finished concrete surface for example, bump cutting of pavement, fin removal from struct ural concrete and terrazzo floor grinding.
Finishing Cl 3.163: Leveling, smoothing, compacting, and otherwise treating surfaces of fresh or recently placed concrete or mortar to produce desired appearance and service.
Float Finish Cl 3.164: A rather rough concrete surface texture obtained by finishing with a float.
Floating Cl 3.165: The operation of finishing a fresh concrete or mortar surface by use of a float.
Fog Curing Cl 3.166: Storage in a moist room in which the desired high humidity is achieved by the atomization of fresh water (see 3.215).
Free Fall Cl 3.168: Descent of freshly mixed concrete into forms without dropchutes or other means of confinement; also the distance through which such descent occurs; also uncontrolled fall of aggregate.
Granolithic Finish Cl 3.169: A surface layer of granolithic concrete which may be laid on a base of either fresh or hardened concrete.
Grant Slope Cl 3.170: The natural slope of fluid grout injecte d into preplaced aggregate concrete.
Groove Joint Cl 3.172: A construction joint created by forming a groove in the surface of a pavement, floor slab, or wall to control random cracking.
Grout Cl 3.173: Mixture of cementitious material and aggregate to which sufficient water is added to produce pouring consistency without segregation of the constituents, or mixtures of other compositions, such as containing PVC or epoxy resin or sodium silicate, but similar consistency (see 3.222).
Grouting Cl 3.174: The process of filling with grout (see 3.172).
Gunning Cl 3.175: Act of applying. shotcrete; ejection of material from nozzle and impingement on surface to be gunned.
Hacking Cl 3.176: The roughening of a surface by striking with a tool.
Hair Cracks Cl 3.177: Cracks which are just visible to the naked eye.
Hairline Cracking Cl 3.178: Small cracks of random pattern in an exposed concrete surface. IS 6461 (Part 7) : 2024 7
Hardener Cl 3.179: A chemical (including certain fluosilicates or sodium silicate) applied to concrete floors to reduce wear and dusting. In a two component adhesive or coating, the chemical component which causes the resin component to cure.
Harsh Mixture Cl 3.180: A concrete mixture which lacks desired workability and consistency due to a deficiency of mortar or aggregate fines.
Heating Rate Cl 3.181: The rate expressed in degrees per hour at which the temperature of the kiln or autoclave is raised to the desired maximum temperature.
High Temperature Steam Curing Cl 3.184: See 3.15 and 3.17.
Holding Cl 3.185: Down Bolt — See 3.14.
Honeycomb Cl 3.186: Voids/cavities formed in concrete due to improper compaction or loss of slurry through the formwork.
Hydration Cl 3.187: Formation of a compound by the combining of water with some other substance; in concrete, the chemical reaction between cement and water.
Interval Vibration Cl 3.188: See 3.334.
Joint Filler Cl 3.190: Material used to fill a joint to prevent the infiltration of debris.
Joint Sealant Cl 3.191: Flexible materials used to prevent ingress of water and other foreign materials across the joints.
Key Cl 3.192: See 3.194.
Keyed or Keying Cl 3.193: Fastened or fixed in position in a notch or other recess.
Keyway Cl 3.194: A recess or groove in one lift or placement of concrete which is filled with concrete of the next lift, giving shear strength to the joint.
Laitance Cl 3.195: A layer of weak and nondurable material containing cement and fines from aggregates, brought by bleeding water to the top of overwet concrete, the amount of which is generally increased by overworking or overmanipulating concrete at the surface by improper finishing or by job traffic.
Layer Cl 3.196: See 3.104.
Lean Concrete Cl 3.197: Concrete of low cement content.
Lift Cl 3.198: The concrete placed between two consecutive horizontal construction joints; usually contains several layers, or courses.
Lift Joint Cl 3.199: Surface at which two successive lifts meet.
Longitudinal Joint Cl 3.200: A joint parallel to the long dimension of a structure or pavement.
Low Cl 3.201: Pressure Steam Curing — See 3.15.
Map Cracking Cl 3.202: See 3.107.
Masonry Mortar Cl 3.203: Mortar used in masonry structures (see 3.219).
Mass Curing Cl 3.204: Adiabatic curing in sealed containers.
Matrix Cl 3.205: In the case of mortar, the cement paste in which the fine aggregate particles are embedded; in the case of concrete, the mortar in which the coarse aggregate particles are embedded.
Maximum Cl 3.206: Temperature Period — A time interval over which the maximum temperature is held constant in an autoclave or steam-curing room.
Mechanical Bond Cl 3.207: The physical keying of one plaster coat to another or to the plaster base by plaster keys to metal lath, or by interlock between adjacent plaster coats by scratching or cross raking; also between concrete and reinforcing bars, the bond attributed to keying of interlocking action other than adhesion.
Membrane Curing Cl 3.208: A process that involves either liquid sealing compound ( for example, bituminous and paraffinic emulsions, coal tar cutbacks, pigmented and non -pigmented resin suspensions, or suspensions of wax and drying oil) or non-liquid protective coating (for example, sheet plastics or waterproof paper), both of which types function as films to restrict evaporation of mixing water from the fresh concrete surface.
Mix Cl 3.209: A colloquial term designating a particular type of concrete mixture (for example, S-bag mix, lean mix and paving mix) the preferable term is ‘mixture’. IS 6461 (Part 7) : 2024 8
Mix Design Cl 3.210: See 3. 250.
Mixing Cycle Cl 3.211: The time taken for a complete cycle in a batch mixer, that is, the time elapsing between successive repetitions of the same operation (for example, successive discharges of the mixer).
Mixing Time Cl 3.212: The period during which the constituents of a batch of concrete are mixed by a mixer, for a stationary mixer, time is given in minutes from the completion of mixer charging until the beginning of discharge for a truck mixer, time is given in total minutes at a specified mixing speed or expressed in terms of total revolutions at a specified mixing speed.
Mixing Water Cl 3.213: The water in freshly mixed sand-cement grout, mortar, or concrete, exclusive any previously absorbed by the aggregate (for example, water considered in the computation of the net water-cement ratio) (see 3.32).
Mixture Cl 3.214: The assembled, blended, intermingled ingredients of mortar, concrete, or the proportions for their assembly.
Moist Room Cl 3.215: A room in which the atmosphere is maintained at a selected temperature and a relative humidity of at least 98 percent, for the purpose of curing and storing cementitious test specimens; the facilities will be sufficient to maintain free moisture continuously on the exterior of test specimens.
Monolith Cl 3.216: A body of plain or reinforced concrete cast or erected as a single integral mass or structure.
Monolithic Surface Treatment Cl 3.217: A dry mixture, usually one part cement to two parts sand, which is sprinkled evenly on an uniformed surface after water has largely disappeared following the strike-off, and then worked off, and then worked in by floating; also called ‘dry shake’.
Monolithic Terrazzo Cl 3.218: The application of a 15 mm terrazzo topping directly to a specially prepared concrete substrata eliminating an underbed.
Mortar Cl 3.219: A mixture of cement paste and sand; when used in masonry construction, the mixture may contain masonry cement, or ordinary hydraulic cement with lime (and possibly other admixtures) to afford greater plasticity and durability than are attainable with ordinary hydraulic-cement paste (see 3.203).
Mud Slab Cl 3.220: A 5 cm to 15 cm layer of concrete below structural concrete floor or footing over soft, wet soil.
Nailer Cl 3.221: A strip of wood or other fitting attached to or set in concrete, or attached to steel to facilitate making nailed connections.
Neat Cement Grout Cl 3.222: A fluid mixture of hydraulic cement and water, with or without admixture; also the hardened equivalent of such mixture.
Net Mixing Water Cl 3.223: See 3.213.
Nominal Mix Cl 3.224: The proportions of the constituents of a proposed concrete mixture.
Open Cl 3.225: Circuit Grouting — A grouting system with no provision for recirculation of grout to the pump.
Oversanded Cl 3.226: Containing more sand than would be necessary to produce adequate workability and a satisfactory condition for finishing.
Overvibration Cl 3.227: Excessive use of vibrators during placement of freshly mixed concrete, causing segregation and excessive bleeding.
Packer Cl 3.228: A device inserted into a hole in which grout is to be injected which acts to prevent return of the grout around the injection pipe usually an expandable device actuated mechanically, hydraulically, or pneumatically.
Pass Cl 3.229: Layer of shotcrete placed in one movement over the field of operation.
Pattern Cracking Cl 3.230: Fine openings on concrete surfaces in the form of a pattern; resulting from a decrease in volume of the material near the surface, or increase in volume of the material below the surface, or both.
Pavement (Concrete) Cl 3.231: A layer of concrete over such areas as roads, sidewalks, airfields, canals, playgrounds, and those used for storage or parking.
Peeling Cl 3.232: A process in which thin flakes of mor tar are broken away from a concrete surface, such as by deterioration or by adherence of surface mortar to forms as forms are removed (see 3.276 and 3.300).
Perimeter Grouting Cl 3.233: Injection of grout, IS 6461 (Part 7) : 2024 9 usually at relatively low pressure, around the periphery of an area which is subsequently to be grouted at greater pressure; intended to confine subsequent grout injection within the perimeter.
Pitting Cl 3.234: Development of relatively small cav ities in a surface, due to phenomena, such as corrosion or cavitation, or in concrete, localized disintegration (see 3.244).
Placeability Cl 3.235: See 3.347.
Place Concrete Cl 3.236: Put fresh concrete into its p ermanent position or into a mould.
Plain Concrete Cl 3.238: Concrete without any reinforcement.
Plaster Cl 3.239: A cementitious material or combination of cementitious material and aggregate that, when mixed with a suitable amount of water, forms a plastic mass or paste which when applied to a surface adheres to it and subsequently hardens, preserving in a rigid state the form or texture imposed during the period of plasticity; also the placed and hardened mixture.
Plaster Consistency Cl 3.240: Condition of freshly mixed cement paste, mortar, or concrete such that deformation will be sustained continuously in any direction without rupture.
Plastic Cracking Cl 3.241: Cracking that occurs in the surface of fresh concrete soon after it is placed and while it is still plastic.
Plastic Shrinkage Cracks Cl 3.242: See 3.178.
Plum Cl 3.243: A large random -shaped stone dropped into freshly placed mass concrete to economize on the volume of the concrete [ see also cyclopean concrete in IS 6461 (Part 4)].
Popout Cl 3.244: The breaking away of small portions of a concrete surface due to internal pressure which leaves a shallow, typical conical, depression.
Pozzolanic Cement Concrete Cl 3.245: Concrete having pozzolana partly substituted for its cement, the pozzolana content being not less than 10 percent of the combined weight of cement plus pozzolana.
Precast Cl 3.246: A concrete member that is cast and cured in other than its final position.
Precured Period Cl 3.247: See 3.249.
Preset Period Cl 3.248: See 3.249.
Presteaming Period Cl 3.249: In the manufacture of concrete products, the time between moulding of a concrete product and start of the temperature rise period.
Proportioning Cl 3.250: Selection of quantity of ingredients for mortar or concrete to make the most economical use of available materials to produce mortar or concrete of the required properties.
Punning Cl 3.252: The process of application of thin coating of slurry or mortar to walls/ceiling.
Rendering Cl 3.253: The application, by means of trowel or float, of a coat of mortar.
Reposting Cl 3.254: The construction operation in which the original shoring or posting is removed and replaced in such a manner as to avoid damage to the partially cured concrete; also known as reshoring.
Retempering Cl 3.255: The addition of water and remixing of concrete or mortar which has started to stiffen.
Revibration Cl 3.256: One or more applications of vibration to concrete after completion of placing and initial compaction but preceding initial setting of the concrete.
Ribbon Loading Cl 3.257: Method of batching concrete in which the solid ingredients, and sometimes also the water, enter the mixer simultaneously.
Rich Concrete Cl 3.258: Concrete of high cement content.
Rich Mixture Cl 3.259: A concrete mixture containing a high proportion of cement. IS 6461 (Part 7) : 2024 10
Rock Pocket Cl 3.260: A porous, mortar -deficient portion of hardened concrete consisting primarily of coarse aggregate and open voids, caused by leakage of mortar from formwork separation (segregation) during placement, or insufficient consolidation (see 3.186).
Rolling Cl 3.261: The use of heavy metal or stone rollers on terrazzo topping to excess matrix.
Rod Tamping (also Called Roding) Cl 3.262: A round, straight steel rod, having one end rounded to a hemispherical tip (see 3.251 and 3.318).
Rough Grind Cl 3.263: The initial operation in which coarse abrasives are used to cut the projecting chips in hardened terrazzo down to a level surface.
Rub Brick Cl 3.264: A silicon-carbide brick used to smooth and remove irregularities from hardened concrete surfaces.
Rubbed Finish Cl 3.265: A finish obtained by using an abrasive to remove surface irregularities from concrete (see 3.269).
Runway Cl 3.266: Decking over area of concrete placement, usually of movable panels and supports, on which buggies of concrete travel to points of placement.
Rustic or Washed Finish Cl 3.267: A type of terrazzo topping in which the matrix is recessed by washing prior to setting so as to expose the chips without destroying the bond between chip and matrix; a retarder is sometimes applied to the surface to facilitate this operation (see 3.155).
Rustication Cl 3.268: A groove in a concrete or masonry surface.
Sack Rub Cl 3.269: A finish for formed concrete surfaces, designed to produce even texture and fill all pits and air holes; after dampening the surface, mortar is rubbed over surface; then, before it dries, a mixture of dry cement and sand is rubbed over it with a wad of burlap or a sponge -rubber float to remove surplus mortar and fill voids.
Sagging Cl 3.270: Subsidence of material from the gun ned surface of a sloping or vertical concrete structural member or from the gunned surface of an overhead horizontal shotcrete structural member (see 3.292).
Sand Blast Cl 3.271: A system of cutting or abrading a surface, such as concrete by a stream of sand ejected from a nozzle at high spread by compressed air; often used for cleanup of horizontal construction joints or for architectural exposure of aggregate.
Sand Cl 3.272: Coarse Aggregate Ratio — Ratio of fine to coarse aggregate in a batch of concrete, by weight or volume.
Sand Grout Cl 3.273: Any Portland cement grout in which fine aggregate is incorporated into the mixture (also termed sanded grout).
Sand Streak Cl 3.274: Streak in surface of formed concrete caused by bleeding.
Sawed Joint Cl 3.275: A joint cut in hardened concrete generally not to the full depth of the member by means of special equipment, utilizing diamond or silicon-carbide blades or discs.
Scaling Cl 3.276: Local flaking or peeling away of the near-surface portion of concrete or morter (see 3.232 and 3.300).
Scour Cl 3.277: Erosion of a concrete surface, exposing the aggregate.
Scratch Coat Cl 3.278: The first coat of plaster or stucco applied to a surface in three -coat work; usually cross raked or scratched to form a mechanical key with the brown coat.
Screeding Cl 3.280: The operation of forming a surface by the use of screeds and a strike -off ( see 3.311).
Segregation Cl 3.281: The differential concentration of the components of mixed concrete, resulting in nonuniform proportions in the mass.
Self Cl 3.282: Desiccation — The removal of free water by chemical reaction so as to leave insufficient water to cover the solid surfaces and to cause a decrease in the relative humidity of the system; applied to an effect occurring in sealed concretes, mortars, and pastes.
Self Cl 3.283: Furring — Metal lath or welded wire fabric formed in the manufacturing process to include means by which the material is held away from the supporting surface, thus creating a space IS 6461 (Part 7) : 2024 11 for ‘keying’ of the insulating concrete, plaster, or stucco.
Separation Cl 3.284: The tendency, as concrete is caused to pass from the unconfined ends of chutes or conveyor belts, or similar arrangements, of coarse aggregate to separate from the concrete and accumulate at one side; the tendency, as processed aggregate leaves the ends of conveyor belts, chutes, or similar devices with confining sides, for the larger aggregate to separate from the mass and accumulate at one side; or the tendency for the solids to separate from the water by gravitational settlement (see 3.35 and 3.281).
Setting Bed Cl 3.285: The mortar subsurface to which a terrazzo topping is applied; usually refers to terrazzo on vertical surfaces.
Settlement (of Aggregate) Cl 3.286: Sinking of the solid particles in fresh concrete or mortar after placement and before initial set.
Shoulder Cl 3.287: An unintentional offset in a formed concrete surface usually caused by bulging of or movement of formwork.
Shrinkage Crack Cl 3.288: Crack due to restraint of shrinkage.
Shrinkage Cracking Cl 3.289: Cracking of a structure or member due to failure in tension caused by external or internal restraints as reduction in moisture content develops, or carbonation occurs, or both.
Single Stage Curing Cl 3.290: Autoclave curing process in which precast concrete products remain on metal pallets until stacked for delivery or yard storage.
Slick Line Cl 3.291: End section of a pipe line used in placing concrete by pump which is immersed in the placed concrete and moved as the work progresses.
Sloughing Cl 3.292: See 3.270.
Slurry Cl 3.293: A mixture of water and any finely divided insoluble material, such as Portland cement, slag, or soil in suspension.
Slush Grouting Cl 3.294: Distribution of a Portland cement slurry with or without fine aggregate as required over a rock or concrete surface which is subsequently to be covered with concrete, usually by brooming it into place to fill surface voids and fissures.
Snap Tie Cl 3.295: A proprietary concrete wall-form tie, the end of which can be twisted or snapped off after the forms have been removed.
Soaking Period Cl 3.296: In high -pressure steam curing, the time during which the live steam supply to the kiln or autoclave is shut off and the concrete products are left to soak in the residual heat or moisture; in low -pressure steam curing, the period after the concrete produc t has reached maximum temperature and during which the steam is shut off and the products are allowed to soak in the residual heat and moisture of the curing kiln.
Sounding Well Cl 3.297: A vertical conduit in the mass of coarse aggregate for preplaced aggregate concrete, provided with continuous or closely spaced openings to permit entrance of grout; the grout level is determined by means of a float on a measured line.
Spading Cl 3.298: Consolidation of mortar or concrete by repeated insertions and withdrawal of a flat, spadelike tool.
Spall Cl 3.299: A fragment, usually in the shape of a flake, detached from a larger mass by a blow, by the action of weather, by pressure, or by expansion within the larger mass (see 3.232 and 3.276).
Spalling Cl 3.300: The development of spalls.
Spatterdash Cl 3.301: A rich mixture of Portland cement and coarse sand which is thrown onto a background by a trowel, scoop or other appliance, so as to form a thin, coarse-textured, continuous coating; as a preliminary treatment before rendering, it assists bond of the undercoat to the background, improves resistance to rain penetration, and even put the suction of variable backgrounds (see 3.119).
Split Batch Charging Cl 3.302: Method of charging a mixer in which the solid ingredients do not enter the mixer together; cement, and sometimes different sizes of aggregate, may be added separately.
Sprinkle Cl 3.303: The distribution of additional chips on a terrazzo topping prior to rolling.
Stage Grouting Cl 3.304: Sequential grouting of a hole in separate steps or stages in lieu of grouting the entire length at once.
Steam Box Cl 3.305: Enclosure for steam curing concrete products. IS 6461 (Part 7) : 2024 12
Steam Curing Cl 3.306: Curing of concrete or mortar in water vapour at atmospheric or high pressures and at temperatures between 30 °C and 215 °C (see 3.15, 3.17, 3.290 and 3.328).
Steam Cl 3.307: Curing Cycle — The time interval between the start of the temperature-rise period and the end of the soaking period or the cooling off period; also a schedule of the time and temperature of periods which make up the cycle.
Steam Cl 3.308: Curing Room — A chamber for steam curing of concrete products at atmospheric pressure.
Steam Kiln Cl 3.309: See 3.308.
Stratification Cl 3.310: The separation of overwet or overvibrated concrete into horizontal layers with increasingly lighter material toward the top; water, laitance, mortar, and coarse aggregate will tend to occupy successively lower positions in that order; a layered structure in concrete resulting from placing of successive batches that differ in appearance.
Strike Cl 3.311: off — To remove concrete in excess of that which is required to fill the form evenly or bring the surface to grade; performed with a straight edged piece of wood or metal by means of a forward sawing movement or by a power operated tool appropriate for this purpose; also the name applied to the tool (see 3.279 and 3.280).
Stub Wall Cl 3.312: Low wall, usually 10 cm to 20 cm high, placed monolithically with concrete floor or other members to provide for control and attachment of wall forms.
Stucco Cl 3.313: A plaster used for coating exterior walls and other exterior surfaces of buildings ( see 3.239).
Sub Cl 3.314: purlin — A light structural section used as a secondary structural member; in lightweight concrete roof construction used to support the form boards over which the lightweight concrete is placed.
Sulphate Attack Cl 3.315: Harmful or deleterious chemical or physical reaction or both between sulphates in soil or ground water and concrete or mortar, primarily the cement-paste matrix.
Sulphate Resistance Cl 3.316: Ability of concrete or mortar to withstand sulphate attack (see 3.315).
Swirl Finish Cl 3.317: A nonskid texture imparted to a concrete surface during final trowelling by keeping the trowel flat and using a rotary motion.
Tampering Cl 3.318: See 3.251.
Tamping Cl 3.319: The operation of compacting freshly placed concrete by repeated blows.
Tesserae Cl 3.320: Small pieces of marble tile or glass used in mosaics.
Thin Cl 3.321: Shell, Precast — Precast concrete characterized by thin slabs and web sections.
Tieback Cl 3.322: A steel rod fastened to a deadman or a rigid foundation to prevent the lateral movement of formwork, sheet pile walls, retaining walls, etc.
Tie Cl 3.323: Bar — A deformed bar or plain round bar embedded in a concrete construction at a joint and designed to hold abutting edges together, but not designed for direct load transfer as a dowel.
Tilt Cl 3.324: Up — A method of concrete construction in which members are cast horizontally at a location adjacent to their eventual position, and tilted into place after removal of moulds.
Transverse Joint Cl 3.326: A joint parallel to the intermediate dimension of a structure.
Trial Batch Cl 3.327: A batch of concrete prepared to establish or check proportions of the constituents.
Two Cl 3.328: Stage Curing — A process in which concrete products are cured in low-pressure steam, stacked, and then autoclaved.
Underbed Cl 3.329: The base mortar, usually horizontal, into which strips are embedded and on which terrazzo topping is applied.
Undersanded Cl 3.330: With respect to concrete, contain ing an insufficient proportion of the fine aggregate to produce optimum properties in the fresh mixture, especially workability and finishing characteristics.
Unit Water Content Cl 3.331: The quantity of water per unit volume of freshly mixed concrete, often expressed as l/m of concrete; the quantity of water on which the water -cement ratio is based, not including water absorbed by the aggregate. IS 6461 (Part 7) : 2024 13
Vent Pipe Cl 3.332: A small-diameter pipe used in concrete construction to permit escape of air in a structure being concreted or grouted.
Vibrated Concrete Cl 3.333: Concrete compacted by vibration during and after placing.
Vibration Cl 3.334: Energetic agitation of freshly mixed concrete during placement by mechanical oscillating devices at moderately high frequency to assist in its consolidation. a) External vibration employs a vibrating device attached at strategic positions on the forms and is particularly applicable to manufacture of precast items and for vibration of tunnel-lining forms; b) Internal vibration employs a vibrating element which can be inserted into the concrete at selected locations, and is more generally applicable to in -place construction; and c) Surface vibration employs a portable horizontal platform on which a vibrating element is mounted.
Vibration Limit Cl 3.335: That time at which fresh concrete has hardened sufficiently to prevent it becoming mobile when subjected to vibration.
Volume Batching Cl 3.336: The measuring of the constituent materials for mortar or concrete by volume.
Warping Cl 3.337: A deviation of a slab or wall surf ace from its original shape, usually caused by temperature or moisture differentials or both within the slab or wall (see 3.116).
Warping Joint Cl 3.338: A joint with the sole function of permitting warping of pavement slabs when moisture and temperature differentials occur in the pavement, that is, longitudinal or transverse joints with bonded steel or tie bars passing through them.
Wash (or Flush) Water Cl 3.339: Water carried on a truck mixer in a special tank for flushing the interior of the mixer after discharge of the concrete.
Water Cl 3.340: Cement Ratio — The ratio of the amount of water, exclusive only of that absorbed by the aggregates, to the amount of cement in a concrete or mortar mixture; preferably stated as a decimal by weight.
Waterstop Cl 3.342: A thin sheet of metal, rubber, plastic, or other material inserted in a construction joint to obstruct the seeping of water through the joint.
Weakened Cl 3.343: Plane Joint — See 3.172.
Weathering Cl 3.344: Changes in colour, texture, strength, chemical composition of other properties of a natural or artificial material due to the action of the weather.
Weight Batching Cl 3.345: Measuring the constituent materials for mortar or concrete by weight.
Wettest Stable Consistency Cl 3.346: The condition of maximum water content at which cement grout or mortar will adhere to a vertical surface without sloughing.
Workability Cl 3.347: That property of freshly mixed concrete or mortar which determines the ease and homogeneity with which it can be mixed, placed, compacted, and finished.
Yield Cl 3.348: The volume of freshly mixed concrete produced from a known quantity of ingredients, the total weight of ingredients divided by the unit weight of the freshly mixed concrete; also, the number of product units, such as block, produced per bag of cement or per batch of concrete. IS 6461 (Part 7) : 2024

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