Soil stabilization is critical in construction, impacting the stability and longevity of infrastructure. Traditional materials such as cement, lime and fly ash have long been used for this purpose. Previous research has demonstrated the effectiveness of cement and lime for stabilizing clayey soils. This study builds on that foundation by investigating the innovative use of sugarcane bagasse ash (BA), an agricultural by-product, as a sustainable alternative for soil improvement. BA and lime were added to clayey soil in varying proportions (0%, 4%, 8% and 12% by dry weight) to assess their impact. Geotechnical tests, including Proctor compaction, unconfined compressive strength (UCS) and California Bearing Ratio (CBR) tests, were performed on both unstabilized and stabilized soil samples, with each test repeated three times for accuracy. The results showed that adding BA and varying lime contents significantly improved the soil's maximum dry density (MDD) and UCS, with specific mixtures yielding peak values. The UCS of the stabilized soil increased by 300% to 400% compared to unstabilized soil, while CBR values improved by 61.32% in soaked conditions and 50% in unsoaked conditions. These enhancements suggest that BA and lime mixtures can effectively improve the performance of clayey soils in construction, potentially reducing dependence on conventional materials. The chemical interaction between lime and BA likely contributes to this improvement through pozzolanic reactions, forming cementitious compounds that enhance soil strength and stability. Of all the combinations, the combination of 8% BA and 12% lime provided the greatest improvements in MDD, optimum moisture content (OMC), CBR and UCS. This research not only addresses environmental concerns regarding waste disposal but also aims to optimize soil properties, contributing to safer, more durable infrastructure while promoting sustainability.

The subgrade is a crucial part of the pavement structure, as it transmits the load of vehicles on the pavement to the subsoil. The stability of the pavement depends on the stability characteristics of the subgrade. Roadwork waste materials (RWM) constitute a significant portion of waste materials used for roadway construction, particularly in base fill and backfill layers. Due to the shortage of virgin raw aggregates from quarries, alternative materials, such as RWM, are used as replacements in regular roadway construction. This research conducted a wide range of laboratory and field evaluations to determine the engineering properties of pond ash (PA) and reclaimed asphalt pavement (RAP), focusing on bottom ash as a blended material. Geotechnical parameters, such as particle size and mechanical properties of the materials, were assessed to evaluate their performance in pavement base or sub -base applications. The interaction of integrity between pond ash, RAP, and natural backfill as homogeneous materials was assessed by examining consistency characteristics concerning optimum moisture content (OMC) and maximum dry density (MDD). Six proportions of pond ash, RAP, and backfill soil (PA, RAP, NBS) were identified and used, with the optimal proportion being 50%:30%:20%. The grain size of RAP required for soil testing suitability will be obtained by disintegration using an earth hammering machine.