Particle size effect of pre-wet zeolites on autogenous shrinkage and mechanical properties of LECC

Abstract

The conservation effects can vary significantly when utilizing zeolite internal curing (IC) agents of different particle sizes in Lightweight Engineered Cementitious Composites (LECC). This paper addresses this issue by investigating the impact of zeolites with varying particle sizes (with average particle sizes of 90 μm, 240 μm, and 410 μm) on the mechanical and shrinkage properties of LECC. Furthermore, it delves into the intrinsic influencing mechanisms through pore characterization parameters and quantitative techniques for assessing the degree of hydration. The results demonstrate that the particle size of zeolite exerts a substantial influence on the conservation efficiency of LECC. Specifically, small-sized zeolite effectively eliminates pores larger than 200 μm within the LECC matrix, resulting in significant enhancements in its mechanical properties (a 16% increase in compressive strength) and shrinkage resistance (a 54% reduction in shrinkage). Conversely, large-sized zeolite diminishes the mechanical properties of LECC, albeit contributing to some extent to improved shrinkage properties (a 32% reduction in shrinkage). The improved conservation effect of small-sized zeolite stems from the refined pore structure and the filling effect of volcanic ash. Pore structure analysis reveals that small-sized zeolite yields a finer pore structure, primarily distributed within the 12 μm range. This enhances water absorption and release, consequently improving conservation efficiency. Additionally, hydration product analysis indicates that small-sized zeolite promotes cement hydration, resulting in a 9% increase in the degree of cement hydration.