Effectiveness of natural zeolite as a mineral admixture in concrete

Abstract

Natural zeolite is a type of mineralogical material containing large quantities of reactive Si02 and AI203 It is widely used in the cement industry in China as a cement blending material. Like other pozzolanic materials such as silica fume and fly ash, zeolite contributes to concrete strength mainly through the pozzolanic reaction with Ca(OH)2, This paper presents experimental results on the compressive strength, degree of pozzolanic reaction, and porosity of zeolite modified cement pastes and concrete. These results are compared with those obtained from similar cement pastes and concrete prepared with silica fume and fly ash replacements. Based on the experimental results, it can be concluded that natural zeolite is a pozzolanic material, with a reactivity between that of silica fume and fly ash. The effectiveness of zeolite as a mineral admixture to high-performance concrete in terms of strength improvement is also between silica fume and fly ash. Generally, zeolite contributes better to strength in concrete than in cement pastes, like other pozzolanic materials such as silica fume. A 15% zeolite reduced the porosity of the cement pastes after 3 days of curing and increased the strength of the concrete after 7 days of curing. A higher replacement of 25% zeolite did not show beneficial effects.