Feasibility of lime and biopolymer treatment for soft clay improvement: a comparative and complementary approach

Abstract

Highway pavement infrastructure projects which involve soil improvement should be executed, ensuring environmental sustainability. In the present study, guar gum (GG) and lime were assessed for the purpose of soft clay stabilization. The experimental program for the soil stabilization employed a two-stage process. The initial stage involves treatment of the soil with various percentages of lime (3, 5, 7, and 9%) and GG (0.6, 1.0, 1.4, and 1.8%), maintaining the same material acquisition cost and considering curing (0, 7, 14, and 28 days) for the unconfined compressive strength (UCS). In the second experimental stage, a complementary approach in which 3% lime was combined with GG at various percentages (0.1, 0.2, and 0.3%) was employed. The tests conducted include UCS, California bearing ratio (CBR), and strength loss resistance (SLR). Results show that the sole use of lime and GG resulted in significant improvement in the UCS, albeit lime was better. While UCS improved with curing time for the lime-stabilized soil, UCS gain for GG occurred only for up to 7 days curing because biodegradation of GG by microbes in the soil ensues on further curing. Lime-GG stabilization resulted in better UCS and CBR improvement with curing than lime stabilization; however, lime stabilization yielded better SLR. The optimum additive content for strength improvement was obtained at 3% lime + 0.3% GG. Microstructural analysis indicated cementation in the stabilized soil. Predictive models for the UCS were developed based on regression methods. Model evaluation revealed that Gaussian process model provided the best UCS prediction.

Geotechnical Investigation of Gelatin Biopolymer on Cohesive Soils

“…This is also a reason for the relative reduction in CBR when compared to the other two-clay soils. The underperformance of the biopolymer-treated soils under submerged conditions could be due to the non-uniform, modified gel matrix in the treated soil [49]. For CL and ML soils, electrostatic interaction and adsorption were greater due to the opposing charges of the clay-gelatin complex.…”

“…Mohan and Adarsh [52] observed an increase in the CBR of highly compressible clay soil after treatment with guar gum biopolymer and added that extending the soaked curing period up to 28 days further enhanced the CBR values by 500%. Onah et al [49] improved the CBR of a low plastic clay soil from 11.9% to 121% with the addition of lime and guar gum biopolymer. A similar finding of CBR increase has been reported for an anionic biopolymer in contact with clay soil by Hamza et al [54], who improved the CBR of fat clay with xanthan gum biopolymer by 848%.…”

β-Glucan as a Sustainable Alternative to Stabilize Pavement Subgrade

“…The addition of sodium alginate in concentrations of 2% for clayey and 4% for silty soils increased the stiffness and brittle behavior of the soils. Utilization of guar gum biopolymer in combination with lime resulted in an improvement in the UCS and California bearing ratio (CBR) of the soil by 650% [ 6 ]. Smitha et al [ 7 ] strengthened silty sand with agar biopolymer and improved its ability to withstand liquefaction.…”