Admixtures
Admixtures are defined as materials other than water, aggregate, and portland cement; used as ingredients for concrete and added
before or during mixing
_______ _______gains measured at three separate times for both treated and untreated concrete.
Compressive strength
A reasonable rule of thumb is an air content of ___ +/- ____ percent
6% ± 1%.
_________ have little cementitious action when used alone. When combined with cement and water, they form cementitious compounds.
Pozzolans
The loss or removal of soluble materials by or into a liquid.
Leaching
_______ ________ are added near the end of the mixing process in either powder or liquid form
Chemical admixtures
Flexural and tensile strength have typically decreased somewhat by the
28-day mark.
________ _______take up air space, making concrete denser
Latex Admixtures
_____ are used in concrete flatwork to help control plastic shrinkage cracking and are also commonly used in shotcrete
Fibers
Small, usually cone-shaped cavities in a horizontal concrete surface, often left after an aggregate close to the surface has expanded and fractured the surrounding concrete, or as the result of adding a calcium-chloride admixture in its dry form
Popouts
Water reducers lower the volume of water required while providing superior workability. The water can usually be reduced by ____ to _____ percent
5% to 10%.
________ _______ are needed to offset the effect of hot weather or to delay the initial set of concrete.
Retarding admixtures
Antifreeze compounds is a calcium nitrate commonly used, which also increases the
compressive strength
________ ______do not react chemically with concrete, absorb water, or affect mix-water requirements
Polymeric fibers
A byproduct of silicon metal or ferrosilicon alloy production
Silica fume
_____________ can reduce water content by as much as 40%.
Superplasticizers
Hydroxylated carboxylic acid reduces water by ____ to _____ percent.
5% to 8%.
Supplementary cementitious materials are added to increase paste volume or offset poor
aggregate gradation
________ _____ increase the flexural strength and improve concrete’s resistance to abrasion and impact.
Steel fibers
A measure of the amount of heat, per time unit and per some unit of area, that can be conducted by a substance
Thermal conductivity
__________ are commonly used in cold weather conditions to permit earlier form removal than the weather generally allows.
Accelerators
__________ retarder reduces water by 5% to 10%.
Lignosulfonate
Pozzolanic and cementitious materials improves
workability
______ ______are used to reinforce thin-sheet concrete products.
Glass fibers
A bundle of thin glass fibers
Stand