| Cement, Portland (ASTM C150) (Concrete Engineering) | 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 | (Concrete Engineering) 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 | (Concrete Engineering) The colloidal gel (glue like) material that makes up the major portion of the porous mass of which hydrated cement paste is composed. |
| Cementitious | (Concrete Engineering) Having cement-like, cementing, or bonding type properties. Material or substance producing bonding properties or cement-like materials. |
| Chair(s) | (Concrete Engineering) In concrete formwork, the support for the reinforcing steel. |
| Change of State | (Concrete Engineering) 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. |
| Cold Joint | (Concrete Engineering) 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 | (Concrete Engineering) A gel-like mass which does not allow the transfer of ions |
| Condensation | (Concrete Engineering) When a moisture laden gas comes in contact with a cooler surface a change of state from gaseous to liquid occurs. |
| Consistency | (Concrete Engineering) The degree of plasticity of fresh concrete or mortar The normal measure of consistency is slump for concrete and flow for mortar. |