Chemical admixtures are dosed in small amounts, usually fluid ounces per hundred pounds of cementitious material (oz/cwt), to adjust water demand, set time, air content or durability. US standards sort them by letter: A water reducing, B retarding, C accelerating, D water reducing and retarding, E water reducing and accelerating, F high-range water reducing, G high-range and retarding. Air entrainers, corrosion inhibitors, shrinkage reducers and viscosity modifiers form their own groups.
Admixture rep says bump the mid-range to six ounces per hundredweight and the finishers will quit begging for water.
Also heard as
- admix
- chemicals
- chemical admixture
Related terms
HRWR
High-range water reducer, the superplasticizer that makes concrete flow without adding water.
Accelerator
An admixture that speeds up setting and early strength gain, mostly used in cold weather.
Retarder
An admixture that delays setting, used in hot weather, on long hauls and for big continuous placements.
Air entrainment
Deliberately building billions of microscopic air bubbles into concrete so it survives freezing and thawing.