Use of Zeolite as Both Internal Curing Agent and Supplementary Binder in Mortar

Abstract

Internal curing with sand-like zeolite particles is effective in reducing shrinkage of cement-based materials, but it decreases the compressive strength. In order to obtain cement-based materials with lower shrinkage and higher strength, zeolite can be used as both internal curing agent and supplementary binder, due to its pozzolanic activity. In this study, the effects of particle size and calcination treatment on internal curing performance and supplementary binding performance of zeolite in cement mortar were experimentally investigated. The pore structure, chemical bond characteristics, water absorption/release behaviors, and pozzolanic activity of zeolite particles were investigated. Cement hydration products, interior relative humidity, and drying moisture loss of mortar specimens containing zeolite were also investigated. The results show that (1) fine zeolite particles can improve the compressive strength, relative humidity, water retention property, and pore structure of cement mortar more obviously than coarse zeolite particles, because they have larger pore size and higher pozzolanic activity; (2) calcination treatment can improve the internal curing performance of coarse zeolite particles, because coarse particles can lose more combined water after calcined; and (3) calcination decreases the pozzolanic activity of zeolite, especially for fine particles.