Abstract
Abstract
This review identifies key challenges in zeolite-based concrete, including reduced early-age performance, high porosity, limited data on fracture properties, and inconsistent findings across studies. The physical characterization shows that zeolite is highly porous with a rough surface texture, and its chemical composition is rich in clinoptilolite with abundant silica and alumina, which supports pozzolanic reactivity. Zeolite increases water demand and reduces workability. Mechanical results demonstrate that compressive, tensile, and flexural strengths improve at optimal replacement but decline at higher replacement. However, the literature does not support a universal optimum replacement level. Many studies have reported improved mechanical performance at 10–15 % zeolite replacement. However, several other investigations observed different optimum levels or satisfactory performance at higher replacement percentages. The variations are due to zeolite type, fineness, chemical composition, mixture proportions, curing conditions, and testing age. Therefore, the mechanical performance of zeolite-based concrete should not be generalized through a single optimum value. Also, zeolite improves self-healing concrete by enhancing bacterial immobilization, crack closure, and strength recovery. Furthermore, zeolite significantly reduces the carbon footprint and global warming potential of concrete, offering additional benefits in lightweight applications when used as a partial sand substitute.