New binary paper/wood industry waste blend for solidification/stabilisation of problematic soil subgrade: macro-micro study

This article presents the potential application of paper/wood industry waste by-products, i.e. lignosulphonate (LS) in conjunction with lime (LM) [i.e. LS-based cementing admixture (LSCA)] to mitigate desiccation induced cracking and mechanical vulnerabilities of expansive soil subgrade. The results showed that the LSCA and lime (LM) significantly ameliorated the soil consistency, subgrade strength characteristics (i.e. California bearing ratio and resilient modulus), and completely mitigated the swelling potential with enhanced resistance against S_r. Moreover, the LSCA and LM notably reduced the 3D-volumetric shrinkage and crack intensity factor (CIF) by 90.1 and 87.4%, respectively. The mineralogical and microstructural analyses manifested that the LSCA induced new cementitious compounds (i.e. hydrates of calcium silicate and calcium aluminate), and substantially enhanced the interlocking among the soil particles compared to the untreated and LS-treated soils. Besides, pavement thickness analyses showed that the LSCA treated subgrade, omits the provision of sand cushion and sub-base course promoting road material conservation.