Glossary - Design and Control of Concrete Mixtures - page 327

Glossary

The intent of this Glossary is to clarify terminology used in concrete construction, with special emphasis on those
terms used in Design and Control of Concrete Mixtures. Additional terminology that may not be in this topic is
included in the Glossary for the convenience of our readers. Other sources for terms include ACI Committee 116,
and ASTM standards.

Air-entraining portland cement —- portland cement
containing an air-entraining addition added during its
manufacture.
Air void —entrapped air pocket or an entrained air
bubble in concrete, mortar, or grout. Entrapped air
voids usually are larger than 1 mm in diameter;
entrained air voids are smaller. Most of the entrapped
air voids should be removed with internal vibration,
power screeding, or rodding.
Alkali-aggregate reactivity —production of expansive
gel caused by a reaction between aggregates containing
certain forms of silica or carbonates and alkali hydrox-
ides in concrete.
Architectural concrete —concrete that will be perma-
nently exposed to view and which therefore requires
special care in selection of concrete ingredients, form-
ing, placing, consolidating, and finishing to obtain the
desired architectural appearance.
Autoclaved cellular concrete —concrete containing
very high air content resulting in low density, and cured
at high temperature and pressure in an autoclave.

A
Absorption —see Water absorption.
Accelerating admixture —admixture that speeds the
rate of hydration of hydraulic cement, shortens the
normal time of setting, or increases the rate of harden-
ing, of strength development, or both, of portland
cement, concrete, mortar, grout, or plaster.
Addition —substance that is interground or blended in
limited amounts into a hydraulic cement during manu-
facture—not at the jobsite—either as a “processing
addition” to aid in manufacture and handling of the
cement or as a “functional addition” to modify the
useful properties of the cement.
Admixture —material, other than water, aggregate, and
hydraulic cement, used as an ingredient of concrete,
mortar, grout, or plaster and added to the batch imme-
diately before or during mixing.
Aggregate —granular mineral material such as natural
sand, manufactured sand, gravel, crushed stone, air-
cooled blast-furnace slag, vermiculite, or perlite.
Air content —total volume of air voids, both entrained
and entrapped, in cement paste, mortar, or concrete.
Entrained air adds to the durability of hardened mortar
or concrete and the workability of fresh mixtures.
Air entrainment —intentional introduction of air in the
form of minute, disconnected bubbles (generally
smaller than 1 mm) during mixing of portland cement
concrete, mortar, grout, or plaster to improve desirable
characteristics such as cohesion, workability, and dura-
bility.
Air-entraining admixture —admixture for concrete,
mortar, or grout that will cause air to be incorporated
into the mixture in the form of minute bubbles during
mixing, usually to increase the material's workability
and frost resistance.

B
Batching —process of weighing or volumetrically
measuring and introducing into the mixer the ingredi-
ents for a batch of concrete, mortar, grout, or plaster.
Blast-furnace slag —nonmetallic byproduct of steel
manufacturing, consisting essentially of silicates and
aluminum silicates of calcium that are developed in a
molten condition simultaneously with iron in a blast
furnace.
Bleeding —flow of mixing water from a newly placed
concrete mixture caused by the settlement of the solid
materials in the mixture.