Performance and ecological assessment of eco-friendly high-strength cementitious matrix incorporating pottery sand derived from heavy metal sludge

This study used pottery sand from heavy metal sludge to mitigate high shrinkage in the high-strength cementitious matrix (HSCM), which simultaneously serves as a solution to environmental concerns. The results show that both coarse and fine pottery sand can effectively reduce the autogenous shrinkage of HSCM. When the replacement rate of coarse pottery sand is 47.5 %, the autogenous shrinkage can be reduced by 73.2 % at the age of 90 days. The strength advantage of pottery sand gradually manifests as curing age increases, and the high replacement rate of coarse pottery sand can increase the strength of HSCM by 56 % at the age of 28 days. The results of the hydration heat test and the internal temperature and humidity test showed that adding pottery sand is beneficial in delaying the hydration peak and increasing the humidity in the middle and late stages. SEM-BSE and X-CT also revealed that the incorporation of pottery sand was beneficial in improving the pore structure and strengthening the interfacial transition zone, which indicates that pottery sand can effectively be utilized as an internal curing agent in HSCM, thereby enhancing the performance of HSCM. The leaching test results demonstrate the effective consolidation of heavy metals by the HSCM, with leaching concentration below regulatory limits. This achievement can provide effective technical support for the high-value resource utilization of heavy metal sludge. • The effects of pottery sand on the shrinkage were comprehensively investigated. • The internal curing mechanism of pottery sand on the HSCM was deeply explored. • The environmental risks and costs were systematically evaluated.