Study on Mixing Cement-Waste By-Product to Stabilize Soft Marine Clay

Improving the engineering properties of low-strength soft marine clay in an environmentally friendly method has become a challenge. The conventional treatment technology for soft soil is cement reinforcement, which will cause severe environmental pollution. In this study, cement and three waste by-products (ground granulated blast furnace slag (GGBS), lime, and fly ash) were used to address the insufficient strength of soft marine clay and reduce environmental pollution. Based on the mixture test design, the laboratory experiment (unconfined compressive tests) was conducted to analyze the strengths of solidified clay cured for 7 days, 14 days, and 28 days with different mixing proportions. According to the analysis of the 28 days strength of solidified clay using the software Design Expert, the optimum dosages of GGBS, lime, fly ash, and cement were determined, which were 2.14%, 2.36%, 0%, and 3%, respectively, named XZ22. In addition, the cost analysis of waste by-products and cement solidified soft marine clay was studied. The result showed that XZ22 was cheaper than cement when the strength of solidified clay was nearly equal. The scanning electron microscopy (SEM) result indicated that stabilized soil's main products were needle-like C-S–H, C–A–H, and ettringite, attributed to the hydration and pozzolanic reactions. The reaction involving GGBS, lime, fly ash, cement, and soil minerals produced the above products, which had the filling-in and cementation effects of enforcing the strength of soft marine clay.