Experimental feasibility research on a high-efficiency cement-based clay stabilizer

Abstract

In many civil engineering constructions, soft clayey soils are often stabilized with Ordinary Portland Cement (OPC) whose production process is energy intensive and emits a large quantity of CO2. In this paper, an OPC-based clay stabilizer (CSCN) which contains some eco-friendly materials is studied to compare with OPC by investigating the mechanical properties of the stabilized clays. Microstructural and mineralogical studies using Scanning Electron Microscope (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) are performed to reveal the mechanisms controlling the development of the strength and modulus. The test results indicate that the compressive strength and secant modulus increase with increasing the content of CSCN and curing age. To achieve the equivalent improvement of the strength and modulus, much less CSCN is needed relative to OPC, which illustrates that CSCN can be a more effective and relatively eco-friendly clay stabilizer. The analysis on pH values and moisture consumption indicates that the hydration and pozzolanic reactions in CSCN-stabilized clays may be quicker than those in OPC-stabilized clays. The microstructural analyses confirm the formation of C-S-H gels in stabilized clays and the types of C-S-H gels are dependent upon the Ca/Si molar ratio according to EDX results. The types and amounts of new minerals in stabilized clays are the possible mechanisms controlling the enhancement of mechanical properties.