High-strength concrete mixture with calcined zeolite particles for shrinkage reduction

Abstract

In this study, calcined zeolite particles with average size of 0·18 mm were used as an internal curing agent for high-strength concrete. The purpose of the study was to explore the mixture design of high-strength concrete with the addition of the calcined zeolite particles. Three high-strength concrete mixtures containing the same amount of pre-wetted calcined zeolite particles, but with varied replacement ratios of cement and sand in the mixture, were designed and the shrinkage and internal relative humidity of each concrete were measured simultaneously under sealed and surface-drying conditions. The test results show that the internal relative humidity of concrete is greatly increased after using pre-wetted calcined zeolite particles in concrete, while the autogenous and drying shrinkage of high-strength concrete are considerably reduced. The efficiencies in shrinkage decrease and humidity increase are influenced by the replacement ratio of zeolite to cement in the mixture. The durability test results show that the addition of porous zeolite increases the permeability of early-age high-strength concrete. Nevertheless, this negative effect is decreased with increasing age. At 90 d after casting, permeability of concrete with pre-wetted zeolite addition is already less than that of control concrete.