Utilization of waste marine dredged clay in preparing controlled low strength materials with polycarboxylate superplasticizer and ground granulated blast furnace slag

Abstract

To solve the disposal of massive waste marine dredged clay (MDC), this study proposes a new method of utilizing it in preparing controlled low strength materials (CLSM). In which the polycarboxylate superplasticizer (PCE) and ground granulated blast furnace slag (GGBS) were used to break the current dilemma that the flowability and strength can only be guaranteed by simultaneously increasing the water content and cement content. The flowability, strength and hydration conductivity were investigated through a series of flow tests, unconfined compression strength (UCS) tests and hydraulic conductivity tests, the microstructure and mineralogical tests were performed to reveal the mechanism of PCE and GGBS accordingly. The results show that GGBS provides more active silicon and active aluminum to promote the generation of hydrated calcium silicate (CSH) and hydrated calcium silicate aluminate (CASH), leading to a higher strength and impermeability of CLSM with GGBS than CLSM with pure ordinary Portland cement (OPC). PCE disperses both MDC and PCE in the CLSM and improves flowability through electrostatic force and steric hindrance, contributing to a rapid increase of flowability under 0.4% of PCE content. Under the collaborative effects of PCE and GGBS, MDC-based CLSM achieves higher strength and flowability at relatively lower cement content and water content, which not only solves the contradiction between flowability and strength of conventional CLSM, but also offers scientific references to the broad application of solid wastes (MDC and GGBS) in CLSM preparation, which promotes the sustainable development of green construction materials significantly.