Beneficiation of Natural Zeolite through Flash Calcination for Its Use as a Mineral Admixture in Concrete

Abstract

Zeolite is a naturally occurring pozzolanic material that can be beneficiated through calcination, resulting in more efficient usage in concrete as a mineral admixture. The present study analyzes the physicochemical characteristics of a natural zeolite and the same zeolite calcined under different conditions. It is seen that optimum pozzolanic reactivity and specific surface area are obtained when the calcination is done at 800°C for 8 min. The water and superplasticizer demands in cementitious binders with zeolite have also been determined. It is shown that mortars and concretes with zeolite, especially with calcined zeolite, perform well in terms of strength and durability characteristics, such as permeability and corrosion, compared to concrete with Class F fly ash (FA) and to plain concrete. In terms of autogenous shrinkage, the performance of natural zeolite is better than that of calcined zeolite and the FA considered. In general, the results indicate that calcined zeolite can be used as a mineral admixture in the production of high-performance concrete, with properties comparable to those of the FA considered, with the exception of the fluidity properties.