Influence of clay calcination method on the mechanical properties and chloride diffusion resistance of limestone calcined clay cement (LC3) concrete

Abstract

Calcined clay plays an important role in the performance of limestone calcined clay cement (LC3) concrete. In this study, the performance of two different types of calcined clay produced from different calcination processes were investigated in chloride environment. The characteristics of the calcined clays, including mineral composition, chemical composition, particle size distribution, specific surface area and particle morphology, were evaluated. Based on the reactivity of the calcined clays, the compressive strength of concretes after up to 28 days of curing was adopted as the best measure to determine the appropriate replacement levels of Portland cement by LC3 to satisfy standards requirements for concrete in chloride environments. The chloride bulk diffusion test was conducted to investigate the performance of LC3 concretes in comparison with reference Portland cement concrete. Similar chloride diffusion resistance could be achieved by using the two different calcined clays in LC3 concrete. The performance of both LC3 concretes was much better than that of reference concrete. However, the Portland cement substitution rate for each calcined clay was governed by the compressive strength standard requirements.