Formwork for Concrete

IS 6461 (Part 8) — Cement Concrete: Glossary of Terms (First Revision, October 2024) · 2024 definitions.

Part 7 Part 9Definitions quoted verbatim from the BIS standard

Absorption Cl 3.1: The process by which a liquid is drawn in to and tends to fill permeable pores in a porous solid body; also the increase in weight of a porous solid body resulting from the penetration of a liquid into its permeable pores.
Acceleration Cl 3.2: Increase in velocity or in rate of change, especially the quickening of the natural progress of a process, such as hardening, setting, or strength development of concrete.
Agglomeration Cl 3.4: Gathering into a ball or mass.
Air Content Cl 3.5: The volume of air voids in cement p aste, mortar, or concrete, exclusive of pore space in aggregate particles, usually expressed as a percentage of total volume of the paste, mortar, or concrete.
Air Entraining Cl 3.6: The capability of a material or process to develop a system of minute bubbles of air in cement paste, mortar, or concrete (see 3.7).
Air Entrainment Cl 3.7: The occultation of air in the form of minute bubbles (generally smaller than 1 mm) during the mixing of concrete or mortar (see 3.6).
Air Void Cl 3.8: A space in cement paste, mortar, or concrete filled with air; an entrapped air void is characteristically 1 mm or more.
Alkali Cl 3.9: Aggregate Reaction — Chemical reaction in mortar or concrete between alkalis (sodium and potassium) from Portland cement or other sources and certain constituents of some aggregates; under certain conditions, deleterious expansion of the concrete or mortar may result.
Antogenons Healing Cl 3.10: 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 3.11: Change in volume produced by continued hydration of cement exclusive of effects of external forces or change of the water content or temperature.
Average Bond Stress Cl 3.12: Maximum force in an embedde d reinforcing bar divided by the product of the perimeter and the length of the reinforcing bar.
Bleed Cl 3.13: To undergo bleeding (see 3.14).
Bleeding Cl 3.14: 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. 1 IS 6461 (Part 8) : 2024 To access Indian Standards click on the link below: https://www.services.bis.gov.in/php/BIS_2.0/bisconnect/knowyourstandards/Indian_standards/isdetails/
Bleeding Capacity Cl 3.15: The ratio of volume of water released by bleeding to the volume of paste or mortar.
Bleeding Rate Cl 3.16: The rate at which water is released from a paste or mortar by bleeding.
Bond Strength Cl 3.17: Bond stress at the instant before failure of concrete bond.
Bulk Density Cl 3.18: The weight of a material (including solid particles and any contained water) per unit volume including voids.
Characteristic Strength Cl 3.19: Strength of material below which not more than 5 percent of the test results are expected to fall.
Compacting Factor Cl 3.20: The ratio obtained by dividing the observed weight of concrete which fills a container of standard size and shape when allowed to fall into it under standard conditions of test, by the weight of compacted concrete compacted by a standard procedure of rodding ( see IS 1199) which fills the same container.
Compressive Strength Cl 3.21: The measured m aximum resistance of a concrete or mortar specimen to axial loading; expressed as force per unit cross-sectional area.
Concrete, Dense Cl 3.22: Concrete containing a minimum number of voids.
Concrete, Fat Cl 3.23: A concrete containing a large proportion of mortar.
Consistency Cl 3.24: The relative mobility or ability of freshly mixed concrete or mortar to flow, the usual measurements are slump for concrete and flow for mortar, cement paste, or grout.
Consistency Factor Cl 3.25: A measure of out flu idity roughly analogous to viscosity, which described the ease with which grout may be pumped into pores or fissures; usually a laboratory measurement, in which consistency is reported in degrees of rotation of a torque viscometer in a specimen of grout.
Contraction (or Expansion), of Concrete Cl 3.26: The sum of volume changes occurring as the result of all processes affecting the bulk volume of a mass of concrete (see 3.76).
Core Strength Cl 3.27: Compressive strength of a concrete assessed from a core sample. Compressive strength of concrete made with a specific concrete mix using a specified cuboid specimen.
Creep Cl 3.28: Time-dependent deformation due to load.
Cube Strength Cl 3.29: The load per unit area at wh ich a standard cube fails when tested in a specified manner.
Drying Shrinkage Cl 3.31: Contraction caused by m oisture loss.
Durability Cl 3.32: The ability of concrete to resist wea thering action, chemical attack, abrasion, and other conditions of service.
Early Strength Cl 3.33: Strength of concrete or m ortar developed soon after placement usually during the first 72 h.
Effective Modulus of Elasticity Cl 3.34: Combination of elastic and plastic effects in an over- all stress-strain relationship in the service structure; often expressed as: 𝐸eff = 1 1 + 0.4(𝐸c/𝐸f) 𝐸c where 𝐸c = modulus of elasticity of concrete; and 𝐸f = modulus of elasticity of the foundation rock.
Elasticity Cl 3.35: That property of a material by v irtue of which it tends to recover immediately its original size and shape after the load which causes the deformation is removed.
Elastic Modulus Cl 3.36: The ratio of normal stress co rresponding to strain for tensile or compressive stresses below the proportional limit of material; also referred to as ‘modulus of elasticity’, ‘Youngs modulus’ and ‘Young’s modulus of elasticity’ ; denoted by the symbol E.
Entrained Air Cl 3.37: Microscopic air bubbles in tentionally incorporated in mortar or concrete during mixing.
Entrapped Air Cl 3.38: Air voids in concrete which ar e not purposely entrained.
Expansion of Concrete Cl 3.39: See 3.26. 2 IS 6461 (Part 8) : 2024
False Set Cl 3.40: The rapid development of rigidity in a freshly mixed Portland cement paste, mortar, or concrete without the evolution of much heat; this rigidity can be dispelled and plasticity regained by further mixing without addition of water (also known as premature stiffening, hesitation set, early stiffening and rubber set).
Fatigue Cl 3.41: The weakening of a material caused by repeated, cyclic or alternating loads.
Fatigue Strength Cl 3.42: The greatest stress which can be sustained for a given number of stress cycles without failure.
Final Set Cl 3.43: A degree of stiffening of a mixture of ce ment and water greater than initial set, generally stated as an empirical value indicating the time in hours and minutes required for a cement paste to stiffen sufficiently to resist to an established degree, the penetration of a weighted test needle; also applicable to concrete and mortar mixtures with use of suitable test procedures (see 3.53).
Final Setting Time Cl 3.44: The time required for a freshly mixed cement paste, mortar, or concrete to achieve final set (see 3.54).
Flash Set Cl 3.45: The rapid development of rigidity in a freshly mixed Portland cement paste, mortar, or concrete, usually with the evolution of considerable heat, which rigidly cannot be dispelled nor can the plasticity be regained by further mixing without addition of water; also referred to as quick set or grab set.
Flat Slab Cl 3.46: Reinforced concrete slab without beams or with nominal beams, but with or without drops, which is supported by columns with or without flared column heads or capitals.
Flexural Strength Cl 3.47: Strength of concrete as determined by the flexural test as per IS 516 (Part 1/Sec 1).
Grade of Concrete Cl 3.50: An identifying number, which is numerically equal to the characteristic
Honeycombing Cl 3.51: Interconnected voids in concrete caused by loss or lack of mortar.
Initial Drying Shrinkage Cl 3.52: The difference between the length of a specimen (moulded and cured under stated conditions) and its length when first dried to constant length, expressed as a percentage of the moist length.
Initial Set Cl 3.53: A degree of stiffening of a mixture of cement and water less than final set, generally stated as an empirical value-indicating the time and hours and minutes required for cement paste to stiffen sufficiently to resist to an established degree, the penetration of a weighted test needle; also applicable to concrete or mortar with use of suitable test procedures (see 3.43).
Initial Setting Time Cl 3.54: The time required for a freshly mixed cement paste, mortar or concrete to achieve initial set.
Initial Stress Cl 3.55: Stress imposed in the concrete or steel of a prestress concrete structural member when it is first fully stressed and before creep or plastics yield occurs.
Local Bond Stress Cl 3.56: Bond stress at a particular point on reinforcement.
Loss on Ignition Cl 3.57: The percentage loss in weight of a sample of cement mortar or concrete ignited to constant weight at a specified temperature, usually 900 °C to 1 000 °C.
Mechanical Bond Cl 3.58: 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 or interlocking action other than adhesion.
Permeability to Water, Coefficient of Cl 3.60: The rate of discharge of water under laminar flow conditions through a unit cross -sectional area of a porous medium under a unit hydraulic gradient and standard temperature conditions usually 20 °C. 3 IS 6461 (Part 8) : 2024 compressive strength at 28 days expressed in MPa.
Porosity Cl 3.62: The ratio, usually expressed as a percentage, of the volume of voids in a material to the total volume of the material, including the voids.
Pressed Edge Cl 3.64: Edge of a footing along with the greatest soil pressure occurs under conditions of over turning.
Remouldability Cl 3.66: The readiness with which freshly mixed concrete responds to a remoulding effort such as jigging or vibration causing it to reshape its mass around reinforcement and to conform to the shape of the form (see 3.48).
Restrained Shrinkage Cl 3.67: Contraction of hardened concrete or mortar caused by evaporation of water from its mass.
Retardation Cl 3.68: Reduction in the rate of hardening or setting, that is, an increase in the time required to reach initial and final set or to develop early strength of fresh concrete, mortar, or grout.
Rheology Cl 3.69: The science dealing with flow of materials, including studies of deformation of hardened concrete, the handling and placing of freshly mixed concrete, and the behaviour of slurries, pastes, and the like.
Rich Concrete Cl 3.70: Concrete of high cement content.
Rodability Cl 3.71: The susceptibility of fresh concrete or mortar to compaction by means of a tamping rod.
Set Cl 3.73: The condition reached by a cement paste, mortar, or concrete when it has lost plasticity to an arbitrary degree, usually measured in terms of resistance to penetration or deformation; initial set refers to first stiffening; final set refers to attainment of significant rigidity.
Setting Shrinkage Cl 3.74: A reduction in volume of concrete prior to the final set of cement, caused by settling of the solids and by the decrease in volume due to the chemical combination of water with cement.
Setting Time Cl 3.75: See 3.44 and 3.54.
Shrinkage Cl 3.76: Volume decrease caused by dryin g and chemical changes; a function of time but not of temperature or of stress due to external load (see 3.26 and 3.31).
Slump Cl 3.77: A measure of consistency of freshly mixed concrete or mortar, or stucco equal to the subsidence measured to the nearest 6 mm of the moulded truncated cone immediately after removal of the slump cone.
Specific Heat Cl 3.78: The amount of heat required per unit mass to cause a unit rise of temperature, over a small range of temperature; for ordinary concrete and steel it is approximately 0.22 and
Splitting Tensile Strength Cl 3.79: Tensile strength of concrete determined by a splitting tensile test as per IS 516 (Part 1/Sec 1).
Strength, Creep Cl 3.80: The stress that causes a given creep in a given time and at a specified temperature.
Strength, Shear Cl 3.81: The maximum shearing s tress which a material is capable of developing, based on the original area of cross section.
Strength, Tensile Cl 3.82: Maximum stress which a material is capable of resisting under axial tensile loading, based on the cross-sectional area of the specimen before loading.
Strength, Ultimate Cl 3.83: The maximum resistance to load that a member of structure is capable of developing before failure occurs; or, with reference to cross sections of members, the largest moment, axial force or shear, a structural concrete cross section will support.
Strength, Yield Cl 3.84: The stress, less than the maximum attainable stress, at which the ratio of stress to strain has dropped well below its value at the low stress, or at which a material exhibits a specified limiting deviation from the usual proportionality of stress to strain.
Swelling Cl 3.85: Volume increase caused by wettin g or chemical changes, or both, a function of time but not of stress due to external load.
Temperature Cracking Cl 3.86: Cracking due to tensile failure, caused by temperature drop in members subjected to external restraints or temperature differential in members subjected to internal restraints. 4 IS 6461 (Part 8) : 2024
Toughness Cl 3.87: The property of matter which r esists fracture by impact or shock.
Transverse Strength Cl 3.88: A property of a solid that indicates its ability to withstand bending.
Turbidimeter Fineness Cl 3.89: The fineness of material, such as Portland cement, usually expressed as total surface area in square centimeters per gram, as determined with the turbidimeter (see 3.92).
Void Cl 3.90: Cement Ratio — Volumetric ratio of air plus water to cement.
Volume Change Cl 3.91: An increase or decrease in v olume.
Wagner Fineness Cl 3.92: The fineness of materials, such as Portland cement expressed as total surface area in square centimetres per gram, determined by the Wagner turbidimeter apparatus and procedure.
Wettest Stable Consistency Cl 3.94: The condition of maximum water content at which cement grout or mortar will adhere to a vertical surface without sloughing.
Workability Cl 3.95: That property of freshly mixed concrete or mortar that determines the ease with which it can be mixed, placed, consolidated, and finished to a homogenous condition.

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