Classification of Concrete Admixtures
High-range water reducing admixtures, also known as superplasticizers, can reduce the water content of a concrete mix by 12-25%, which aids in increasing the strength of the given mix. Superplasticizers can also be used to produce concrete with greatly increased slump (flowing concrete) while maintaining a desired water/cement ratio. For example, adding a normal dosage rate of superplasticizer to concrete with a slump of 3-4 inches will produce a concrete with a slump of 7-8 inches. This value added mixture may be helpful when placing concrete into foundation walls containing reinforcing steel.
Mid-range water reducing admixtures can reduce the water content of a mix by 5-18%. Mid-range water reducers offer advantages relative to workability and can improve the finishing characteristics of the concrete. When added to the mix, mid-range water reducers also offer excellent pumpability and finishability.
Accelerators are used to reduce the setting time of fresh concrete and accelerate the early strength gain of hardened concrete. When setting time is reduced, finishing operations are completed faster, thus offering a cost savings relative to labor. Essroc Ready Mix offers calcium chloride accelerators and non-chloride accelerators based on the customer's requirements and project specifications. Accelerating admixtures are recommended when placing concrete in cold weather.
Retarding admixtures are used to delay the set time of fresh concrete. Retarders slow the rate of slump loss and allow the concrete to be workable for a longer period of time and may delay initial set by an hour or longer. Retarding mixtures are recommended when placing concrete in hot weather.