Sustainable Reduction of Cracking and Shrinkage of Marine Soil Through Alkali Activated Fly Ash
Authors :- Wanare, R., Reddy, A.S., Iyer, K.K.R.
Publication :- Ground Improvement I, IGC 2023, Lecture Notes in Civil Engineering, vol 662. Springer, 2025.
Desiccation cracking causes degradation of strength properties of the subsoil system and allows percolation of water into the subsurface. It has adverse effects on performance and stability of soil structures that includes slope failures, erosion of bank levees, and increase in settlement of soil strata. Hence, to minimize such effects it is necessary to reduce/mitigate soil cracking. Researchers have presented the studies on crack reduction with conventional admixtures such as lime and cement. However they contribute to significant carbon emissions during their manufacturing/production leading to the negative effects on the environment. In this regard, the present study attempts to utilize a sustainable binder (viz., industrial by-product, Fly ash, with different activators) for reduction/mitigation of cracking and shrinkage of marine soil. Desiccation tests have been performed in the laboratory at 27 °C ± 2 °C temperature with 50% ± 5% humidity which resembles the natural drying conditions. Cracking with shrinkage, and shrinkage without cracking have been evaluated with CSIF (crack and shrinkage intensity factor) and SIF (shrinkage intensity factor), respectively. The admixture proportions have been varied up to 15%, by varying percentage of Fly ash, lime (1–3%) and alkaline materials (1–3%) such as KOH, NaOH, Na2CO3 and Na2SiO3. Crack mitigation and significant shrinkage reduction has been achieved in the study for some combinations. The study results are quite encouraging toward potential application of alkali activated Fly ash for mitigation/reduction of cracking in marine soils and dredged materials.