Improving strength and hydraulic characteristics of regional clayey soils using biopolymers

This paper portrays a unique demonstration of sustainable low-cost ground improvement for regional soil deposits, by comparing locally sourced biopolymer soil stabilisation soil with imported biopolymer stabilisation. The conventional materials often utilized for soil and ground improvement come with major challenges of large carbon footprints and some negative environmental impacts. As a result, suitable eco-friendly and sustainable materials are necessary. In this study, the potential use of Rice Husk Powder (RHP), Cassava Peel Powder (CPP) and Carboxymethyl Cellulose (CMC), as biopolymer-based materials to improve the engineering properties of a regional clay was investigated using a gamut of geotechnical compaction, strength and hydraulic conductivity tests according to BS 1377, 1990. The results revealed that locally sourced CPP performed better than both imported CMC and local RHP in improving the engineering properties of the regional clay. The shear strength value of the natural clayey soil (43.5 kPa) increased twenty and ten times respectively when treated with CPP (893 kPa) and CMC (450 kPa). One percent content of CPP and CMC performed optimally among the (0.5, 1.0, 1.5, 2 and 2.5) percent studied in improving the engineering properties of the case study regional clay. [Display omitted] •Evaluation of agro-wastes as innovative additives for in situ soil stabilization.•Cassava peel powder (CPP) is an optimum local biopolymer for soil improvement.•Low-cost CPP biopolymer outperformed imported Carboxymethyl Cellulose (CMC).•Geotechnical demonstration of biopolymer potentials in re-engineering weak soils.•A bio-coating mode of action was established from microstructural evaluation.