Evaluation of Engineering Properties of Expansive Soils Mixed with Waste EPS Beads-Paper

Paper

Pdf Summary

The study evaluates recycled expanded polystyrene (EPS) beads as an additive for reducing the swelling of expansive soils. Three laboratory-made clay soils with different plasticity levels were prepared by mixing sand with 30%, 40% or 50% sodium bentonite. Waste EPS blocks were crushed into 3–10 mm beads and added at 0.5%, 0.75% and 1% of soil weight.<br /><br />Standard Proctor compaction, one-dimensional swelling-pressure and unsoaked California Bearing Ratio (CBR) tests were conducted. Increasing EPS content generally reduced maximum dry density and CBR, while optimum moisture content tended to rise. Both the percentage swell and swelling pressure decreased as EPS content increased. The soil with the highest bentonite content had the greatest swelling, reflecting its larger expansive-clay fraction.<br /><br />The results indicate a trade-off: EPS beads can mitigate swelling, with the greatest reported reduction in swelling pressure at 1% EPS, but they also reduce the composite soil’s strength and bearing capacity. The authors suggest that chemical stabilizers may be needed where greater strength is required. They conclude that waste EPS could be a viable additive for controlling subgrade soil swelling, while recommending attention to the loss of CBR and density.

Keywords

recycled expanded polystyrene

EPS beads

expansive soils

swelling reduction

swelling pressure

sodium bentonite

standard Proctor compaction

California Bearing Ratio

soil stabilization

waste EPS