Select the letter of a term you would like defined. You may select any letter section of the glossary from any glossary page.

• Calcareous - Containing calcium carbonate or, less generally, containing the element calcium.
• Calcine - To alter composition or physical state by heating to a specific temperature for a specific length of time.
• Calcium Aluminate Cement - The product obtained by pulverizing clinker consisting essentially of hydraulic calcium aluminates resulting from fusing or sintering a suitable proportioned mixture of aluminous and calcareous materials.
• Capillarity - A wick-like action whereby a liquid will migrate vertically through material, in a upward direction; as oil in a lamp travels upward through the wick.
• Capillary - In cement paste, any space not occupied by anhydrous cement or cement gel. Air bubbles, whether entrained or entrapped, are not considered as part of the cement paste.
• Carbonation - (1) Reaction between the products of portland cement (soluble calcium hydroxides), water and carbon dioxide to produce insoluble calcium carbonate (efflorescence). (2) Soft white, chalky surface dusting of freshly placed, unhardened concrete caused by carbon dioxide from unvented heaters or gasoline powered equipment in an enclosed space. (3) Carbonated, dense, impermeable to absorption, top layer of the surface of concrete caused by surface reaction to carbon dioxide. This carbonated layer becomes denser and deeper over a period of time. Reaction with carbon dioxide which produces a slight shrinkage in concrete. Improves chemical stability. Concrete masonry units during manufacturing may be deliberately exposed to carbon dioxide after reaching 80% strength to induce carbonation shrinkage to make the units more dimensionally stable. Future drying shrinkage is reduced by as much as 30%.
• Cellular Concrete - A lightweight product consisting of portland cement, cement-pozzolan, cement sand, lime-pozzolan, or lime-sand pastes, or pastes containing blends of these ingredients and having a homogenous void or cell structure, attained with gas forming chemicals or foaming agents. For cellular concretes, containing binder ingredients other than or in addition to portland cement, autoclave curing is usually employed.
• Cement, Portland (ASTM C150) - A powdery substance made by burning, at a high temperature, a mixture of clay and limestone producing lumps called ?clinkers? which are ground into a fine powder consisting of hydraulic calcium silicates. For non-portland cements, see aluminous cement.
• Cement Content - A quantity of cement contained in a unit volume of concrete or mortar, ordinarily expressed as pounds, barrels, or bags per cubic yard.
• Cement Gel - The colloidal gel (glue like) material that makes up the major portion of the porous mass of which hydrated cement paste is composed.
• Cementitious - Having cement-like, cementing, or bonding type properties. Material or substance producing bonding properties or cement-like materials.
• Chair(s) - In concrete formwork, the support for the reinforcing steel.
• 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.
• 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.
• Coefficient of Thermal Expansion - Change in unit length per degree change of temperature.
• 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.
• 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.
• 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 instances, an admixture.
• Condensation - When a moisture-laden gas comes in contact with a cooler surface, a change of state from gaseous to liquid occurs.
• Consistency - The degree of plasticity of fresh concrete or mortar The normal measure of consistency is slump for concrete and flow for mortar.
• 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.
• 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.

Contributions: Kaiser Cement, Portland Cement Association, Concrete Manual, Bureau of Reclamation, U. S. Department of the Interior and many other publications, with special thanks to Bob Cameron of W. R. Meadows. © 2008 Moxie International, Inc. All Rights Reserved.

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