Abstract

Pozzolans are being extensively used as a partial cement replacement in the production of Portland cement concrete. The advantages of using pozzolans are lower costs and better durability, however it requires longer setting time and the strength development at the initial age is slower. Different methods have been developed to overcome these disadvantages and to enhance the reactivity of natural pozzolans. There are three ways which have been used to improve the pozzolanic reactivity; it includes mechanical method, thermal method and chemical method. The utilization of the chemical method as an activator of pozzolanic reactivity has received considerable attention in recent years. In this paper the effect of using different chemical activators on pozzolanic activity of a pozzolan is summarized by reviewing previously published work. It was found that proper chemical activators can be used as an addition to concrete containing pozzolans which later can increase the reaction rate of pozzolanic activity and compressive strength significantly.

Key words: Pozzolan, chemical activators, strength.