A study to investigate the effect of different proportion of ultrafine slag and calcium-based activator for sustainable crack mitigation of marine soil

Abstract

Marine soils are prone to cracking and shrinkage during drying. Various infrastructure facilities constructed on marine soils may experience safety and stability issues due to cracking of soil, that results in accelerated ingress of water, increase in compressibility of soil, reduction in bearing capacity of soils, slope erosion and reduction in its stability. Hence studies focused on sustainable crack mitigation are necessary to improve its engineering properties. In this regard, the present study explores the role of ultrafine slag (US) with calcium-based activator (lime(L)/cement (C)) for sustainable crack mitigation of marine soil (MS). Crack and shrinkage intensity factor (CSIF) has been utilized to quantify the cracking and shrinkage characteristics for unstabilized and stabilized marine soil. The study confirms CSIF reduction upto 50 % for MS + 12 %US + 3 %L, while crack mitigation has been achieved for different combinations (MS + 7 %US + 3 %L, MS + 12 %US + 3 %L, MS + 13 %US + 2 %L, MS + 9 %US + 1 %C, MS + 13.5 %US + 1.5 %C). It has also been observed based on indirect stability test (crumb test) that MS + 12 %US + 3 %L exhibits enhanced stability to water inundation, followed by MS + 7 %US + 3 %L, as compared to other combinations of stabilized soil that exhibited effective crack mitigation. The evaluation of cone penetration resistance (an indirect measure of shear and tensile strength of soil) of unstabilized and stabilized marine soil specimen, at different water contents, suggests that tensile strength of soil shall be higher than tensile stresses at all times, for crack mitigation. The findings of the study may be useful towards possible utilization of ultrafine slag with lime/cement for stabilization of in situ marine soil/dredged material in offshore/near shore environment.