Study on mechanical properties and microstructure of metakaolin-slag-calcium carbide residue synergistic solidifying waste engineering mud

Abstract

Utilizing MSC composite materials (M-Metakaolin(MK)), S-Slag, C-Calcium carbide residue (CCR)), the waste engineering mud produced through the drilling and grouting pile construction method was solidified.Through the analysis of unconfined compressive strength (UCS), X-ray diffraction (XRD), and scanning electron microscope (SEM) on solidified engineering mud test blocks, the influence of complex factors such as slag content, CCR content, and curing time on the solidification efficiency of engineering mud was investigated, and the microscopic mechanism was analyzed.Concurrently, supplementary tests were carried out to ascertain the pH and water content of the cured mud.The results indicated that the 7-day unconfined compressive strength of cured mud specimens could achieve 3 MPa when incorporating 12 % MK, 8 % slag, and 6 % CCR.The optimal pH for the curing mud is determined to be 11.25, correlating with a water content of 84 %.The destructive strains corresponding to the peak stresses of the cured mud at different curing times ranged from 1.6 % to 2.5 % and generally decreased with increasing peak stresses.The XRD and SEM analyses have demonstrated that the enhancement in the strength of the cured mud can be attributed to the processes of hydration and polymerization, resulting in the generation of gel products such as calcium silicate hydrate (CSH) and aluminosilicate-Na hydrate (NASH). These products are responsible for the adsorption of clay and bentonite particles, thereby efficiently occupying the structural voids.The research findings have the potential to provide theoretical support for the development of environmentally friendly and low-carbon MSC gelling materials, as well as their application in soil reinforcement, notably in the context of engineered mud solidification.