Effect of Natural Zeolite on Mechanical Properties and Autogenous Shrinkage of Ultrahigh-Performance Concrete

Abstract

In this study, different percentages of silicafume (SF) were replaced with natural zeolite (NZ) (25%, 50%, 75%, and 100%), in order to mitigate autogenous shrinkage of ultrahigh-performance concrete (UHPC) with almost equivalent mechanical properties. The results showed that replacement of SF with NZ had a positive effect on maintaining internal relative humidity (RH) in the higher range and consequently reducing the autogenous shrinkage of UHPC. The mixtures with 25%, 50%, 75%, and 100% replacing SF by NZ had lower autogenous shrinkage compared to reference mixtures with 100% SF. The results of microstructure and thermogravimetric analysis showed that NZ had a good pozzolanic activity. The results of the compressive strength indicated showed that by replacing 50% SF with NZ, the 90 days compressive strength was only slightly lower than the reference mix. The relative cost analysis of the samples indicated that replacing SF with NZ yields a cost-effective solution. By replacing SF with NZ, UHPC mix with appropriate compressive strength, low autogenous shrinkage and relatively low cost, can be produced.