A dynamic triaxial test was conducted to assess the deformation characteristics of sodium silicate modified EPS (expanded polystyrene) particle lightweight soil (SCS) under cyclical loading. The hysteresis curves, dynamic elastic modulus, damping ratio, and cumulative strain were obtained for SCS samples with varying EPS particle content. We found that the samples' stress-strain hysteresis curves, became crescent-shaped for different dynamic stress situations, and were largely elastic in the latter phases. Furthermore, there was a progression from dense to sparse as EPS content increased. With increasing dynamic stress, the dynamic elastic modulus and damping ratio of SCS also rose. The damping ratio of SCS rose as the EPS particle content increased, whereas the dynamic elastic modulus decreased. Notably, increases in the PS particle content and dynamic stress largen the deformation of the SCS samples. Moreover, we found that when the cumulative strain curve becomes stable, varying the contents of EPS particles under different dynamic stresses leads to a power function relationship with the logarithm of the number of cyclic loading cycles. In cases where the cumulative strain curve reaches a critical or destruction point, the cumulative damage variable displays a power function relationship with the vibration count.

This paper discusses efforts made by past researchers to steady the expansive (problematic) soils using mechanical and chemical techniques - specifically with EPS beads, lime and fly ash. Administering swelling of problematic soils is critical for civil engineers to prevent structural distress. This paper summarizes studies on reduction of swelling potential using EPS, lime and fly ash individually. Chemical stabilization with lime and fly ash are conventional methods for expansive soil stabilization, with known merits and demerits. This paper explores the suitability of different materials under various conditions and stabilization mechanisms, including cation exchange, flocculation, and pozzolanic reactions. The degree of stabilization is influenced by various factors such as the type and amount of additives, soil mineralogy, curing temperature, moisture content during molding, and the presence of nano-silica, organic matter, and sulfates. Additionally, expanded polystyrene (EPS) improves structural integrity by compressing when surrounded clay swells, reducing overall swelling. Thus, EPS addresses limitations of chemicals by mechanical means. Combining EPS, lime and fly ash creates a customized system promoting efficient, long-lasting, cost-effective and eco-friendly soil stabilization. Chemicals address EPS limitations like poor stabilization. This paper benefits civil engineers seeking to control expansive soil swelling and prevent structural distress. It indicates potential of an EPS-lime-fly ash system and concludes by identifying research gaps for further work on such combinatorial stabilizer systems.

The cyclic swell-shrink behavior of expansive soils poses formidable challenges to both rigid and flexible structures within pavement engineering, necessitating effective mitigation strategies. This research explores the utilization of waste expanded polystyrene (EPS) beads, a byproduct of hand-crushed EPS blocks, to construct recycled geofoam granules columns (GGC) in expansive soil. The objective is to assess the potential of GGC in mitigating swell-shrink phenomena through rigorous cyclic wetting-drying tests. A series of cyclic swelling-shrinkage experiments were conducted in a purpose-built swell-shrink apparatus, maintaining precise laboratory conditions. Remolded soil samples, incorporating GGC with two distinct diameters (40 mm and 75 mm) and a GGC density of 15 kg/m3, underwent cyclic wetting-drying cycles. The experimental data reveals a consistent reduction in the swell-shrink pattern with an increasing number of applied wet-dry cycles. Notably, the largest diameter GGC exhibited a pronounced decrease in the swell-shrink pattern compared to plain soil. Quantitatively, the findings demonstrate a remarkable 28% and 46% reduction in full swelling for 40D and 75D GGC, respectively, showcasing the efficacy of GGC in countering expansive soil tendencies. Equilibrium conditions were rapidly achieved by the 4th and 5th cycles, leading to a substantial 42% and 53% reduction in time requirements for 40D and 75D GGC. These quantitative assessments underscore the promising application of GGC in pavement engineering, offering a sustainable and technically sound solution to the cyclic swell-shrink challenges. The discussion delves into the mechanisms underlying GGC's influence on controlling swell-shrink behavior, emphasizing the pivotal role of soil-geofoam interaction.