Sustainable use of soda lime glass powder (SLGP) in expansive soil stabilization

Abstract

The focus of this experimental study is to ameliorate the engineering behavior of Palygorskite-rich medium Expansive soils (ES) by utilizing soda lime glass powder (SLGP). The hydrophilic ES are problematic and tend to damage the pavements, boundary walls, and slab-on-grade members Whereas, the accumulation of huge amounts of SLGP is responsible for multitude of environmental issues. Therefore, SLGP was added to the ES using various dosage levels (0 %, 6 %, 10 %, 14 %, 16 %, 18 %, and 22 % by dry weight of the ES to assess the compaction, consolidation and strength characteristics by performing geotechnical laboratory tests. Also, the effect of curing on th unconfined compressive strength of ES (UCS-ES) after 3, 7, 14, and 28 days was studied by considering the mineralogical changes. The microscopic mechanisms of the virgin ES and the SLGP-treated mixtures was evaluated by X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses. The results revealed that, plasticity dropped by almost 80 % (due to filler effect, cohesionless character, and higher silica amount of the SLGP), MDD increased from 18.25 to 19.16 kN/m3, and the OMC lowered down (due to the reduction in volume of clay minerals and interlayer spaces). With increasing SLGP dosage levels the coefficient of compression (Cc) decreased by 42.86 %, coefficient of volume (mv) by 60 %, coefficient of consolidation (cv) by 91.53 %, and the pre-consolidation pressures (Pc) witnessed an increase of 240 %. The UCS-ESunsoaked values exceed than the UCS-ES soaked values, particularly at early days of curing (1–7 days) such that UCS-ESsoaked = 13 × UCS-ESsoaked after one day, whereas UCS-ESsoaked = 5.25 × UCS-ESsoaked after 28 days. Similarly, a remarkable improvement (of six -fold) in strength was recorded based on California bearing ratio (CBR) values with 16 % replacement of the SLGP additive. Also, the compactability and strength characteristics were significantly improved and the plasticity plummeted due to formation of C-S-H and C-A-H compounds. Thus, the inclusion of 16 % SLGP in the medium ES was found as the optimum amount in reducing plasticity, improving consolidation characteristics and imparting strength.