Advanced Modeling in Civil Engineering
Mechanical and Microstructural Performance of Clayey Soil Stabilized with Cement and Sodium Silicate Waste (SSW)
Document Type : Original Article
Authors
1 PhD student, Department of Civil Engineering, Faculty of Engineering and Technology, Qazvin Branch, Islamic Azad University, Qazvin, Iran
2 Assistant Professor, Department of Civil Engineering, Faculty of Engineering, Qazvin Branch, Islamic Azad University, Qazvin, Iran
3 Associate Professor, Department of Civil Engineering, Faculty of Engineering, Qazvin Branch, Islamic Azad University, Qazvin, Iran
Abstract
Chemical stabilization is a widely used method for improving the engineering properties of clayey soils. Conventional stabilizers such as cement and lime are effective but costly and environmentally less sustainable. The use of industrial byproducts with pozzolanic activity provides a promising and eco-friendly alternative. This study investigates the combined effect of Type II Portland cement and sodium silicate waste (SSW) on the geomechanical and microstructural behavior of clayey soil. Laboratory tests, including Atterberg limits, compaction characteristics, unconfined compressive strength (UCS), and scanning electron microscopy (SEM), were conducted on untreated and stabilized specimens. Soil samples were treated with 2–8% cement and 2–8% SSW and cured under standard conditions. Results show that SSW significantly enhances soil performance. The plasticity index decreased from 16.1% for untreated soil to 6.4% in the 8% cement + 8% SSW mixture. Compaction tests indicated a reduction in maximum dry density and an increase in optimum moisture content due to particle refinement and filler effects. UCS values increased considerably with curing time, reaching 3649 kPa for the 8% cement + 8% SSW mixture after 42 days, a 14.6-fold increase over untreated soil and 22% higher than cement-only treatment. The 6% cement + 6% SSW mixture achieved 3420 kPa, offering a more cost-effective option. SEM analysis confirmed enhanced bonding and reduced porosity through the formation of C-S-H and C-A-S-H gels. Overall, the combined use of cement and sodium silicate waste provides an efficient, economical, and environmentally sustainable approach for improving the strength, durability, and plasticity of clayey soils.
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