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Moxie International - concrete terms Category: Architecture and Buildings > Cement and concrete terms Date & country: 21/08/2008, USA Words: 180

Retarder
An admixture which extends the setting time of cement paste, and therefore of mixtures such as concrete, mortar, or grout.    

Retempering
The addition of water and remixing of concrete which has started to stiffen: usually not allowed as it may affect the ultimate strength.

Retardation  Delaying
the hardening or strength gain of fresh concrete, mortar or grout. 

Reinforced Concrete
A.       Concrete in which reinforcement, other than that provided for temperature changes for shrinkage, has been embedded in such a- manner that the two materials act together in resisting forces. B. Concrete in which steel bars have been placed to sustain the tensile stresses.

Refractory Concrete
Concrete having refractory properties, suitable for use at high temperatures.  Calcium-aluminate cement and refractory aggregates are normally used for the manufacture of this product.

Rebound
Wet shotcrete or sand and cement which bounces away from a surface again at which pneumatically applied mortar is being projected.

Reactive Aggregate
(See alkali-aggregate reaction)

Pumping
The ejection of a mixture of water and solid materials such as clay or silt along cracks, transverse or longitudinal joints, and along pavement edges caused by downward slab movement due to the passage of heavy loads, machinery or equipment over the pavement after free water has accumulated in or on the subbase, subgrade or basecourse.

Prestressed Concrete
  Concrete in which stresses have been introduced which are opposite in sense to those that the structural member will be expected to carry during its use.

Pretensioning
A method of prestressing reinforced concrete in which the steel is stressed before the concrete has hardened and restrained from gaining its unstressed position by bond to the concrete.

Proportioning
Selection of proportions of material for concrete to make the most economical use of available materials to manufacture concrete of the required strength, placeability, and durability,

Preplaced Concrete
  Concrete manufactured by placing clean, graded coarse aggregate in a form and later injecting a portland cement-sand grout under pressure, to fill the voids.

Precast
A concrete unit, structure or member that is cast and cured in an area other than its final position or place.

Post-tensioning
A method of prestressing concrete in which the tendons are tensioned after the concrete has hardened.

Pozzolan
A siliceous, or siliceous and aluminous material, which in itself possesses little or no cementitious value but will, in a finely divided form, such as a powder or liquid and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form permanent, insoluble compounds possessing cementitious properties.

Portland-Pozzolan Cement
The product obtained by intimately intergrinding a mixture of portland-cement clinker and pozzolan, or an intimate and uniform blend of portland cement and fine pozzolan.

Portland Cement
the product obtained by pulverizing clinker consisting essentially of hydraulic calcium silicates.

Portland Blast
slag Cement Furnace (ASTM C 595)The product obtained by intimately intergrinding or an intimate and uniform blending a mixture of granulated  blast furnace slag and portland-cement clinker

Porosity
The ratio of the volume of voids in the material to the total volume of the material, including the voids, usually expressed as a percentage.

Plasticizer
A material that increases the workability or consistency of a concrete mixture, mortar or cement paste. 

Plastic Consistency
Condition in which concrete, mortar, or cement paste will sustain deformation continuously in any direction without rupture.

Plasticity
Property of freshly mixed concrete, cement paste or mortar which determines its ease of molding or resistance to deformation.

Plastic
A condition of freshly mixed concrete. mortar or cement -paste indicating that it is workable and readily re-moldable, is cohesive, and has an ample content of fines and cement but is not over wet.

Pining
Development of relatively small cavities in a concrete surface, due to phenomena such as cavitation or corrosion.

Plane of Weakness
The plane along which a structure under stress will tend to fracture; may exist because of the nature of the structure and its loading, by accident, or by design.

Peeling
A process in which thin flakes of matrix or mortar are broken away from concrete surface; caused by adherence of surface mortar-to forms as forms are removed, or to trowel or float in portland cement plaster.

Pea Gravel
Portion of concrete aggregate passing the 3/8' sieve and retained on a No.4 sieve.

Particle-Size Distribution
Particle distribution of granular materials among various sizes; for concrete material normally designated as gradation.  Usually expressed in terms of cumulative percentages smaller or larger than each of a series of sieve openings or percentages between certain ranges of sieve openings.

Overvibration
Excessive vibration of freshly mixed concrete during placement-causing segregation.

Ottawa Sand
A sand used as a standard in testing hydraulic cements by means of mortar test specimens.  Sand is produced by processing silica rock particles obtained by hydraulic mining of the orthoquartzite situated in open-pit deposits near Ottawa, Illinois; naturally rounded grains of nearly pure quartz.

Non-evaporable Water
The water in concrete which is irremovable by oven drying; chemically combined during cement hydration.

Non-agitating Unit
A truck-mounted unit for transporting ready-mixed concrete short distances, not equipped to provide agitation (slow mixing) during delivery.

Neat Cement-Paste
A mixture of water and hydraulic cement, both before and after setting and hardening. 

No-Fines Concrete
A concrete mixture in which only the coarse gradation (3/8' to 3/4' normally) of aggregate issued.

Neat Cement
Unhydrated hydraulic cement.

Monolithic
A plain or reinforced mass of concrete cast as a single, one piece, integral structure.

Mortar
A mixture of cement, sand and water. When used in masonry construction, the mixture may contain masonry cement, or standard portland cement with lime or other ad-mixtures which may produce greater degrees of plasticity and/or durability.

Modulus of Elasticity
A measure of the resistance of material to deformation. the ratio of normal stress corresponding strain for tensile or compressive stresses below the proportional limit of the material; elastic modulus is denoted by the symbol '2'.

Moist Room
A room used for storing and curing cementitious test specimens. The atmosphere of this room is maintained at a temperature of 73.4 3.0'F or 23.0*1.7'0 and relative humidity of at least 98 percent.  These facilities must be adequate to continually maintain  free moisture on the exteriors of test specimens.

Mixing Time
For stationary mixers, mixing time is calculated in minutes from the completion of charging the mixer until the beginning of discharge; for truck mixer, time is calculated in total minutes at a specified mixing speed. the period during which materials used in a batch of concrete are combined by the mixer

Mixing Speed
Rate of mixer drum rotation or that of the paddles in a pan, open-top, or trough type mixer, when mixing a batch; expressed in revolutions per minute (rpm) or in peripheral] feet per minute of A point on the circumference at maximum diameter.

Mixer
Equipment used for mixing or blending the materials used in the manufacture of concrete, grout or mortar.

Maximum Size Aggregate
Aggregate whose largest particle size is present in sufficient quantity to affect the physical properties of concrete; generally designated by the sieve size on which the maximum amount permitted to be retained is 5 or 10 percent by weight.

Mass Curing
Adiabatic curing, using sealed containers.

Mass Concrete
Any large volume of concrete cast in place intended to resist applied loads by virtue of mass.  Generally a monolithic structure incorporating a low cement factor with a high proportion of large coarse aggregate.

Masonry Cement
Hydraulic cement manufactured for use in mortars for masonry construction. Normally a blend of two or more of the following materials: portland cement, natural cement, portland-pozzolan cement, hydraulic lime, slag cement, hydrated lime, pulverized limestone, talc, chalk,  pozzolan, clay or gypsum; also may include air en-training additions.

Marl
A calcareous clay, containing approximately 30 to 65 percent calcium carbonate (05003), found normally in extinct fresh wafer basins, swamps, or bottoms of shallow lakes.

Magnetite
An aggregate used in heavy weight concrete, consisting primarily of ferrous metaferrite (Fe304). A black magnetic iron ore with a specific gravity of approximately 5.2 and a Mohs hardness of about 6.

Lift
Layer of concrete.

Liquefaction
The change of state to a liquid.  Term used instead of condensation in reference to substances, which are usually gaseous.

Laitance
A residue of weak and non-durable material consisting of cement, aggregate, fines, or impurities brought to the surface of overwet concrete by the bleeding water

Kelly Ball
A device for determining the consistency of fresh concrete.  It is sometimes used as an alternative to the slump test.

Keene's Cement
A finely ground high density plaster composed of anhydrous, (calcined or 'dead burned') gypsum, the set of which is accelerated by the addition of other materials.

Jacking Force
The temporary force exerted by the jacking device which introduces tension into the tendons.  Jacking Stress In prestress concrete, the maximum stress occurring in a tendon during stressing.

Jacking Equipment
In prestress concrete, the device used to stress the tendons.

Initial stress
In prestressed concrete, the stresses occurring in the prestressed members before any losses occur.

Initial Set
A degree of stiffening of the cement and water mixture. This is a degree lees than final set and is 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. (Refer to ASTM C191 or C286 for weight and penetration data.)

Impermeable
The ability of a material or product to reduce or eliminate gaseous transmissions through it's mass; measured as the rate of Water Vapor Transmission (WVT). Note: Not all materials that are waterproof are vaporproof; all materials that are vaporproof are inherently waterproof.

Hydrologic Cycle
The Hydrologic Cycle consists of the evaporation of water from oceans and other bodies of open water; condensation to produce cloud formations; precipitation of rain, snow, sleet or hail upon land surfaces; dissipation of rain or melted solids by direct run-off into lakes and by seepage into the soil. Thereby producing a continuing endless source of water in the sub-grade.

Hydraulic Cement
A cement that is capable of setting and hardening under water due to interaction of water and the constituents of the cement (ASTM 219).

Hydrogenesis
Another term for condensation.  The term is especially applied to base and soil substrates under highway pavements. where the barometric pump causes the inhalation of humid air, which then condenses in those structures, causing an ever increasing moisture content and sometimes instability.

Hydration
Formation of a compound by the union of water with some other substance. In concrete it is the chemical reaction between water and the cement.  A concrete slab needs to completely hydrate prior to the application of paints, coatings, and flooring materials.

HRM High Reactivity Metakaolin
  Refined form of an ASTM C618, Class N (natural) pozzolan. A high performance, mineral admixture, similar in performance to silica fume, additionally comparable in cost.  Pure white powdered in form will,  not effect the natural color or darken concrete as silica fume does. Suitable for high-performance color matching  in architectural concrete.  Dosage at 5% to 10%,  of cement by weight.  No ble...

Holding Period
Period In the manufacture of concrete products, the period between completion of casting and the introduction of additional heat or the steam curing period.

Gunite
A term sometimes used to designate dry-mix shotcrete.

Heat of Hydration
The quantity of heat expressed in calories per gram, evolved upon complete hydration of portland cement at a given temperature.

Grout
A fluid mixture of (1) cement, sand, and water or (2) cement and water: the hardened equivalent of such mixtures.

Gillmore Needle
A device used in determining time of setting of hydraulic cement, described in ASTM 0 266. Gradation The sizing of granular materials; for concrete materials, usually expressed in terms of cumulative percentages larger or smaller than each of a series of sieve openings or the percentages between certain ranges of sieve openings.

GFRC
Glass Fiber Reinforced Concrete Concrete panels, usually architectural designs, reinforced with a high zirconia (16% minimum), alkali-resistant glass fiber.  Optimum glass fiber content of 5% by weight.  Lower fiber content results in lower early ultimate strengths, higher fiber content can produce composite compaction and consolidation difficulties.

Foam Concrete
(See Cellular concrete)

Gap-graded Aggregate
Aggregate containing particles of both large and small sizes, in which particles of certain intermediate sizes are wholly or substantially absent.

Gas Concrete
(See cellular concrete)

Flexural Strength
A property of a solid that indicates its ability to withstand bending.

Fly Ash
The finely divided residue that results from the combustion of ground or powdered coal, transported from the firebox through the boiler by flue gases.

Flash Set
The rapid development of rigidity in a mixed portland cement paste, mortar or concrete usually with the evolution of considerable heat, which rigidity 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.

Fineness Modulus
An index of fineness or coarseness of an aggregate sample. An empirical factor determined by adding total percentages of an aggregate sample retained on each of a specified series of sieves, and dividing the sum by 100.  Note: US Standard sieve sizes are used: No. 100, No.50, No. 30, No. 16, No. 8, and No. 4, and 3/8 in., 3/4 in., I in.,  2 in., 3 in., and 6 in.

Fine Aggregate
  Aggregate passing the 3/8-in. sieve and almost entirely passing the No.4(4.76 mm) sieve and predominantly retained on the No. 200 (74 micron) sieve(ASTM125).          

False Set
The rapid development of rigidity in a 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.  Premature stiffening, and rubber set are terms referring to the same phenomenon, but false set is the preferred term.

Entrapped Air
Air in concrete which is not purposely en-trained, Entrapped air bubbles are normally much larger and more irregular than entrained air bubbles.

Entrained Air
(See air entrainment) Microscopic air bubbles intentionally incorporated in mortar or concrete, to improve workability and durability (usually imparting a higher degree of resistance to freezing and thawing).

Elastic Shortening
The shortening of a member in pre-stressed concrete which occurs on the application of forces induced by prestressing.

Efflorescence
A crystalline deposit of salts which leach from the concrete as soluble calcium hydroxides and within a short period of time will combine with the atmospheric carbon dioxide to form insoluble calcium carbonates, usually white in color, appearing on the surfaces of masonry, stucco or concrete.

Drying Shrinkage
A decrease in the volume of concrete upon drying.

Durability
The ability of concrete to resist weathering action, chemical attack, and abrasion.

Dry Rodded Weight
The weight of dry aggregate rodded into a cylindrical container of diameter approximately equal to the height, each of 3 layers rodded 25 times, and the excess aggregate struck off level with the top of the container

Dispersing Agent
An admixture capable of increasing the fluidity of pastes, mortars, or concretes by reduction of interparticle attraction.

Density
Weight per unit volume.

Cure
Method of maintaining sufficient internal humidity and proper temperature for freshly placed concrete to assure proper hydration of the cement, and proper hardening of the concrete.

Consolidation
Compaction usually accomplished by vibration of newly placed concrete to minimum practical volume,  to mold it within  form shapes and around  embedded parts and reinforcement, and to eliminate voids other than entrained air.

Construction Joint
The contact between the placed concrete and concrete surfaces, against or upon which concrete is to be placed and to which new concrete is to adhere, that has become so rigid that the new concrete cannot be incorporated integrally by vibration with that previously placed. Unformed construction joints are horizontally placed or nearly so.

Consistency
The degree of plasticity of fresh concrete or mortar The normal measure of consistency is slump for concrete and flow for mortar.

Condensation
  When a moisture laden gas comes in contact with a cooler surface a change of state from gaseous to liquid occurs.

Concrete
A composite material which consists essentially of a binding medium,  within which are embedded particles or fragments of a relative inert filler in portland cement concrete, the binder is a mixture of portland cement, possibly additional cementitious materials such as fly ash and water; the filler may be any of a wide variety of natural or artificial, fine and coarse aggregates; and in some insta...

Colloidal
A gel-like mass which does not allow the transfer of ions

Compressive Strength
The measured resistance of a concrete or mortar specimen to axial loading expressed as pounds per square inch {psi) of cross-sectional area. The maximum compressive stress which material, portland cement, concrete, or grout is capable of sustaining.

Cold Joint
A visible lineation which forms when the placement of concrete is delayed. The concrete in place hardens prior to the next placement of concrete against it.

Coarse Aggregate
Naturally occurring, processed or manufactured,  inorganic particles in prescribed gradation or size range, the smallest  size of which will be retained on the No. 4 (4.76 mm) sieve.

Change of State
The process whereby liquid is heated to the point of evaporation changing the liquid into a gas the condensation of a gas on a cooler surface returning it from gaseous to liquid form.

Chair
In concrete formwork, the support for the reinforcing steel.

Cementitious
  Having cement-like, cementing, or bonding type properties.  Material or substance producing bonding properties or cement-like materials.