The present study investigated the evolution of the time-dependent behavior of remolded samples of Indian black cotton soil for different loading-unloading-reloading cycles in oedometer conditions. The microstructural analysis was carried out to evaluate the parameters such as particle rearrangement and pore size reduction that are responsible for creep at different time periods. It was observed that micropores existed in large numbers, and the number of pores decreased rapidly with an increase in pore size. The number of pores was found to decrease by 20-30% and 85-90% at the intermediate and final stages of the creep test, respectively. Additionally, it was noted that although small pores and mesopores were less in number, they were significant in pore area calculations. The reduction in pore areas for the intermediate and final stages was found to be in the range of 40-50% and 40-60%, respectively, as there were large proportions of micropores that compressed without influencing the overall pore area. The percentage of vertically aligned particles reduced from 21 to 15% at the end of the test. This observation is attributed to the particle rearrangement and reduction in pore sizes that occurred during the test.

To enhance the mechanical properties of problematic black cotton soil, engineers are focusing on reinforcing the soil with geosynthetic materials. This attention is particularly directed towards improving the strength characteristics of black cotton soil, given its inherent challenges associated with volume changes and plasticity. In this comprehensive study, red stone dust waste is introduced in varying percentages ranging from 5% to 35% to stabilize the black cotton soil. The goal is to assess the impact of different proportions of red stone dust on the stabilization of the soil. Furthermore, to augment the stability of the soil, polymer fabric is strategically incorporated at different depths, both in single and double layers. The California Bearing Ratio (CBR) tests are conducted on blends of black cotton soil and red stone dust, with the polymer fabric positioned at depths of H/3 and 2H/3 from the top of the loading surface. The results indicate that the blend containing 25% red stone dust yields the most favorable outcomes in terms of CBR improvement. Additionally, it is observed that the enhancement in CBR values is more pronounced when the reinforcement is applied in a single layer compared to double layers. In summary, the study reveals that the combination of red stone dust and polymer fabric reinforcement offers a promising approach for effectively stabilizing black cotton soil, with the optimal percentage of red stone dust and the configuration of the reinforcement layers playing crucial roles in CBR values.

Geosynthetic materials play a pivotal role in addressing the challenges associated with black cotton soil, a problematic soil type prone to volume changes and exhibiting high plasticity. The primary objective is to enhance the strength properties of black cotton soil through a two-step process. Initially, the soil is stabilized by incorporating varying percentages (5%, 10%, 15%, 20%, 25%, 30%, and 35%) of red stone dust waste. Subsequently, to prepare the stabilized soil for use as a subgrade, geosynthetics are employed for reinforcement, with placement at different depths in both single and double layers. California Bearing Ratio (CBR) tests serve as a key assessment tool for the blends of Black Cotton Soil (BCS) and Red Stone Dust (RSD) with geotextile and geogrid reinforcement. The geosynthetic materials are strategically placed at depths of H/3 and 2H/3 from the top of the loading surface. Among the tested blends, those containing 25% RSD exhibit the most promising results in terms of CBR improvement. Moreover, the study reveals that the incorporation of additional reinforcement in a single layer yields more substantial enhancements in CBR values compared to the double-layer reinforcement approach. Specifically, the findings highlight that a single layer of geogrid, positioned at H/3 depth, outperforms geotextile in a single layer. This research contributes valuable insights into optimizing the stabilization and reinforcement of black cotton soil using a combination of red stone dust waste and geosynthetic materials, offering a comprehensive understanding of the interplay between various parameters for effective soil engineering solutions.