Investigation of the Strength Properties of Silty Clay Soil Stabilized with Lime and Waste Paper Ash

Abstract

In road and pavement construction, a solid and durable foundation is essential. However, a lack of high-quality materials for the subgrade and subbase layers remains a widespread problem. Expansive soils, such as silty clay, frequently have undesirable geotechnical features, such as low bearing capacity, high compressibility, shrinkage and swelling behavior, and high moisture susceptibility. This study aims to improve the strength qualities of silty clay soil from Ozu-Item, Ohaofia, Nigeria, by employing lime and waste paper ash as stabilizing agents, both individually and in combination. Lime was added in proportions ranging from 10% to 20%, whereas waste paper ash was added in amounts ranging from 2% to 4%. Laboratory examinations included sieve analysis, consistency limitations (liquid and plastic), compaction, and California Bearing Ratio (CBR) tests. Statistical analysis and optimization were performed using Design Expert software. The dependent variables, CBR, Optimum Moisture Content (OMC), Maximum Dry Density (MDD), Liquid Limit (LL), and Plastic Limit (PL), were optimized using numerical methods built into the software. The optimal results obtained were as follows: CBR value of 41.8129, OMC of 14.15%, MDD of 1.88698 g/cm3, LL of 26.86%, and PL of 22.94%. These findings were obtained with 42.57 g of waste paper ash, 339.68 g of lime, and 1,256 g of soil, yielding a desirability score of 1.00. The results demonstrate that lime and waste paper ash are useful in improving the strength properties of silty clay soil for pavement building applications.