Concrete admixtures

Abstract

Scope of Study: The purpose of this study is to determine the effects of the different types of admixtures on concrete. The admixture field was divided into groups according to their effects on concrete. The groups include accelerators, retarders, air-entraining agents, gas-forming agents, pozzolans, alkali-aggregate expansion inhibitors, dampproofing and permeability reducing agents, workability agents, grouting agents, and miscellaneous agents. Admixtures help to produce concrete properties that are specifically designed to meet the requirements of a given project. Whether or not to use an admixture in concrete depends on its effectiveness in producing the specific properties desired in concrete.

Findings and Conclusions: Admixtures, when used properly, can improve workability, accelerate setting time, improve durability, reduce bleeding, retard setting time, impart color, control volume change, reduce segregation, and aid in curing of concrete. An admixture should be selected for a specific project based on the results obtained with the same type concrete that will be placed on the project. The amount of an admixture added to a batch of concrete must be carefully controlled because too much of the admixture may impart undesirable characteristics in the concrete. Admixtures should always be obtained from reliable producers who can provide a uniform product. Some type of admixture is added to most of the concrete placed today.