Paper and wood industry waste as a sustainable solution for environmental vulnerabilities of expansive soil: A novel approach

The traditional disposal methods of paper/wood industry raise serious environmental concerns, thus, requires innovative and productive ideas to manage such waste. This article deals with the appraisal and modification of lignosulphonate, a waste by-product of paper/wood industry, as a soil stabilizer to mitigate the disastrous environmental vulnerabilities of expansive soil related to the wetting-drying cycles. In this context, a novel approach of integrating lignosulphonate with hydrated lime was proposed, based on the short comings of lignosulphonate as a lone soil stabilizer. Periodic variations of wetting-drying cycles were assessed on various engineering properties of untreated and treated expansive soils with the optimum percentage of lignosulphonate, hydrated lime, and proposed binary admixture. Micro-fabric changes were also analyzed to evaluate the stabilization mechanism in mitigating the disastrous environmental aspects of expansive soil. The results showed that both untreated and lignosulphonate treated samples underwent suppression in swelling behavior and gain equilibrium at the third wetting-drying cycle. Whereas, the proposed binary admixture exhibited complete mitigation of the swelling behavior and showed significant hindrance against the wetting-drying cycles in terms of compressibility, hydraulic conductivity, and shear strength of soil. In comparison, lignosulphonate alone showed inferior and hydrated lime showed almost similar amelioration of most of the engineering properties accounting the environmental vulnerabilities of expansive soils. The scanning-electron micro-graphs of all the soil samples showed destructed clay structures with more inter assemblage pore spaces upon wetting-drying cycles. Moreover, the proposed binary admixture exhibited better stabilization mechanism than lignosulphonate alone considering the wetting-drying cycles. Evidently, the proposed binary admixture curtails the environmental vulnerabilities of expansive soil, significantly reduces the lime consumption for expansive soil stabilization, and proposes a sustainable and environment friendly waste management for the paper/wood industry.