Integrating lignosulphonate and hydrated lime for the amelioration of expansive soil: A sustainable waste solution

摘要

A sustainable solution to utilize the paper/wood industry waste as a construction material is presented in this article. A novel technique of coupling lignosulphonate (LS) with hydrated lime (LM) is adopted to mitigate the short comings of lignosulphonate as an expansive soil stabilizer. A detailed experimental study was performed on the proposed composite binary admixture (CBA) to ameliorate the geotechnical properties of expansive soil. The optimum binary admixture (OBA) was determined on the basis of plasticity index. For the better apprehension, and further verification of optimum binary admixture, the performance of lignosulphonate was individually assessed at various percentages (0.4%, 0.875% and 2%) and in combination with different percentages of lime (2.625%, 3.82%, 5%, 6.5% and 9%). Various geotechnical properties, such as plasticity, swelling, shrinkage, strength and hydraulic conductivity were analyzed based on the test results. Stabilization mechanism was assesed by X-ray diffraction (XRD) and scanning electrone microscope (SEM). Results showed that using composite binary admixture as a stabilizer exhibits better amelioration of geotechnical properties of expansive soil than using lignosulphonate alone. Whereas, the optimum value of the composite binary admixture was determined to be 3.5% to adequately stabilize the expansive soil. During the stabilization process, the intrinsic structure of clay mineral was observed to be destructed and resulted in the formation of a more stable structure, owing to the ability of the added admixture to trigger the intermolecular interaction and chemical reaction with the clay minerals. Overall, lignosulphonate addition reduces the lime consumption in expansive soil stabilization and also provides a sustainable solution in curtailing the industrial waste. (C) 2020 Elsevier Ltd. All rights reserved.