Decorative Concrete Institute

Bob Harris

Consulting • Education • Installation • Training


Absorption – The process by which a liquid is drawn into and tends to fill permeable pores in a porous solid body; also, the increase in mass of a porous solid body resulting from the penetration of a liquid into its permeable pores.

Accelerating Admixture – An admixture that will shorten the set time of concrete.

Admixture – A material other than water, cement, and aggregate, used to modify concrete’s freshly mixed, setting, or hardened properties.

Aggregate – A granular material such as crushed stone, sand, gravel, or iron blast-furnace slag, used with a cementing medium to form hydraulic-cement concrete or mortar.

Air-Cooled Blast-Furnace Slag – The material resulting from solidification of molten blast-furnace slag under atmospheric conditions; subsequent cooling may be accelerated by application of water to the solidified surface.

Air Content – The volume of air voids in cement paste, 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 Admixture – An admixture that through agitation in production of fresh concrete causes the development of a system of microscopic air bubbles that increase its workability and aid in freeze/thaw resistance.

Batch – Production of a quantity of concrete based on volume, i.e….a cubic yard.

Batch Weights – The measured amount of sand, stone, cement, and water that make up a batch or “load” of concrete.

Blast-Furnace Slag – The nonmetallic product, consisting essentially of silicates and aluminosilicates of calcium and other bases, that is developed in a molten condition simultaneously with iron in a blast furnace.

Caisson – Usually cylindrical in shape. Part of a footing or foundation.

Calcium Chloride – A 32% solution or a solid, when added to concrete acts as a set accelerator.

Cement – Known as Portland Cement, is a hydraulic product, which means it sets and hardens when it chemically interacts with water and is able to do this under water.

Cementitious Material – An inorganic material or a mixture of inorganic materials that sets and develops strength by chemical reaction with water by formation of hydrates and is capable of doing so under water.

Coarse Aggregate – Graded granular material with a nominal maximum size ranging from 1-1/2” down to 3/8”.

Concrete – A composite material that consists essentially of a binding medium within which are embedded particles or fragments of aggregate; in hydraulic-cement concrete, the binder is formed from a mixture of hydraulic cement and water.

Curing – Action taken to maintain moisture and temperature conditions in a freshly-placed cementitious mixture to allow hydraulic cement hydration and (if applicable) pozzolanic reations to occur so that the potential properties of the mixture may develop.

Curing Compound – A liquid that, when applied as a coating to the surface of newly-placed concrete, forms a membrane that retards the evaporation of water and, in the case of white pigmented compounds, reflects heat.

D-Cracking – In concrete, a series of cracks near to and roughly parallel to features such as joints, edges, and structural cracks.

Fine Aggregate – A graded granular material entirely passing the 3/8” sieve.

Fly Ash – The finely divided residue that results from the combustion of ground or powdered coal and that is transported by flue gases from the combustion zone to the particle removal system.

Granulated Blast-Furnace Slag – The glassy, granular material formed when molten blast-furnace slag is rapidly chilled, as by immersion in water.

Grout – A cementitious mixture, with or without admixtures, that is used primarily to fill voids.

High Range Water Reducer (Superplasticizer) – An admixture that can produce a high slump concrete or produce considerable reduction of water with a minimal effect to set time.

Laitance – A layer of weak material derived from Cementitious material and aggregate fines either: 1) carried by bleeding to the surface or to internal cavities of freshly placed concrete, or 2) separated from the concrete and deposited on the concrete surface or in internal cavities during placement of concrete under water.

Lightweight Aggregate – A low density aggregate such as expanded clay or shale, used in lightweight concrete.

Pozzolan – A siliceous or siliceous and aluminous material, which in itself possesses little or no Cementitious value but will, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form compounds possessing Cementitious properties.

Retarding Admixture – An admixture that will lengthen the set time of concrete.

Sand – Fine aggregate resulting from natural disintegration and abrasion of rock or processing of completely friable sandstone.

Segregation – The unintentional separation of the constituents of concrete or particles of an aggregate, causing a lack of uniformity in their distribution.

Setting – The process, due to chemical reactions, occurring after the addition of mixing water, that results in a gradual development of rigidity of a cementitious mixture.

Slump – Used to measure the consistency of ready mix concrete. To perform the slump test, you fill an inverted funnel-shaped cone with concrete. When the cone is removed, the concrete “slumps”. The distance is measured to determine the slump.

Specific Gravity – The ratio of mass of a volume of a material at a stated temperature to the mass of the same volume of distilled water at a stated temperature.

Vapor Barrier – A membrane such as 4 mil plastic placed on grade that when fresh concrete is placed on top of, minimizes the transmission of water vapor into and through the hardened concrete from the sub-grade.

Water Reducing Admixture – An admixture that allows a decrease in water without changing the slump of fresh concrete, or, allows an increase in slump without an increase in water.

Water / Cement Ratio – The Ratio of the mass of water, exclusive only of that absorbed by the aggregates, to the mass of portland cement in concrete, mortar, or grout, stated as a decimal.

Workability of Concrete – That property determining the effort required to manipulate a freshly mixed quantity of concrete with minimum loss of homogeneity.