Assessment of Strength Properties of Clayey Sand Soils Admixed with Marble Powder, GGBS and Geotextile Reinforcement

The use of clayey sand is considered as a low-quality subgrade for pavement construction and presents several challenges. Clayey sand typically has poor engineering properties due to its less strength and high compressibility with moisture changes. This research work is mainly focused on the feasibility of clayey sand to make suitable to use as a subgrade soil when admixed with and ground granulated blast furnace slag (GGBS), which is also termed as Furnace Slag and Marble Powder and reinforced with geotextile. The aim is to evaluating the suitability and find optimum quantities of these additives in improving the soil’s engineering parameters. Different tests were conducted on the soil samples such as grain size distribution, Atterberg’s limits, compaction, California Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS) by different amounts of additives. The soaked and unsoaked California Bearing Ratio values of soil reinforced with Geotextile increased to 4.2% and 6.8%, respectively, at 6% of marble powder. A similar trend of increased strength found in case of Furnace Slag admixed with soil reinforced with geotextile and found as 3.6 and 6.8%, respectively. However, it was found that beyond 6%, there is a decline in California Bearing Ratio, indicating that excess Marble Powder and Ground Granulated Blast Furnace Slag negatively impacts soil strength. The use of geotextile reinforcement significantly enhanced Unconfined Compressive Strength values, with the best performance observed at 6% of Furnace Slag and 8% of Marble Powder obtained as 22.6 kPa and 19 kPa, respectively. Based on the results improvements in subgrade soil strength characteristics, the proposed methodology can be adopted for enhancing strength properties of clayey sand subgrades.