Optimum design of eco-friendly high-strength cementitious matrix incorporating pottery sand derived from sintered heavy metal sludge

Abstract

This paper explored the utilization of pottery sand (PS) sintered from heavy metal sludge (HMS) as fine aggregate in the high-strength cementitious matrix (HSCM), which can reduce the cost and facilitate the reutilization of HMS. To establish function expression for various parameters, D-Optimal Mixture Design (DOMD) method was adopted. Considering the comprehensive effects of multiple influencing factors, the optical mix proportion of HSCM with PS was ultimately proposed. Then, experimental verification was conducted on the proposed optimized mix ratio, indicating the accuracy of DOMD in calculating the mix ratio of the high-strength cementitious matrix with PS. Specifically, the optimal mix proportion exhibits superior performances in improving density, fluidity, mechanical properties, cost-effectiveness, and reducing carbon emissions. The appropriate inclusion of PS primarily serves to enhance the mechanical properties of the matrix and lower costs. The effects of PS on the porous structures and the characteristics of the interfacial transition zone (ITZ) between paste and fine aggregates were evaluated by scanning electron microscope (SEM), combining mercury intrusion porosimetry (MIP) and X-ray computed tomography (X-CT). It is found that the ITZ structure between paste and PS is much denser compared to that between paste and river sand. The appropriate content of PS is beneficial in reducing the mesoscopic porosity of HSCM.