Wood bioash effect as lime replacement in the stabilisation of different clay subgrades

Abstract

ABSTRACT The possibility of applying wood ash (WA), as a partial replacement of lime in subgrade stabilisation of clay soil of eastern Croatia, was explored in this study. The optimal ratios of lime substitution by WA were determined for the stabilisation of local clays of different plasticity. The results show that WA, a local available alternative material, can be used as a partial replacement of lime in the stabilisation of researched local clays for use in embankments and subgrades. The substitution of lime by WA resulted in similar changes in soil plasticity, granulometry and compaction properties. The optimal substitution ratio of lime with WA in the stabilised mixtures depends on the degree of plasticity of the base soil. The lowest optimal substitution ratio was recorded (25–50%) for high-plasticity soil. For medium- and low-plasticity soil, 50–75% of lime can be replaced by WA, resulting in the same or better California Bearing Ratio (CBR) values than the reference mixture. The CBR values for all mixtures were 18.82–107.34%. With the addition of all binder compositions, linear swelling was reduced to less than 1%. However, some aspects of chemical composition of WA can present limitations to WA use.