Enhancing Soil Stabilization: The Influence of Cement and Polymer Additives on the Strength and Performance of Soil-Cement Composites for Unpaved Roads

The stabilization of clayey sand for unpaved roads was investigated to enhance geotechnical properties using cement and polymer additives. Soil samples classified as well-graded sand with clay (SW-SC) were subjected to laboratory analysis to evaluate strength, durability, and load-bearing capacity. Cement incorporation at varying percentages significantly improved unconfined compressive strength (UCS), with the highest value of 2340 kPa observed at a 10% cement content. However, excessive cement additions were found to increase soil brittleness, highlighting the necessity for optimized mix designs. The inclusion of polymers at 6% and 8% concentrations further enhanced the UCS while mitigating the brittleness associated with higher cement proportions. Curing time contributed substantially to strength development, with polymer-modified soil-cement mixtures demonstrating superior performance compared to those without polymers. Optimum moisture content (OMC) conditions were critical, as maintaining moisture slightly above the OMC (+2%) yielded maximum strength gains, whereas deviations resulted in reduced performance. California Bearing Ratio (CBR) tests revealed that cement-stabilized soil with 5% to 9% cement achieved soaked CBR values that were 12.1 to 18.5 times greater than untreated soil, meeting or exceeding standards for base materials in unpaved road construction. The combined use of cement and polymers improved the durability, load-bearing capacity, and mechanical performance of soil-cement composites, offering a sustainable and effective approach for enhancing unpaved road subgrades. These findings emphasize the significance of carefully balancing cement and polymer proportions, moisture conditions, and curing periods to achieve optimal outcomes. This study delivers significant insights into the development of high-performance soil stabilization techniques tailored for unpaved road applications.