Revitalizing dredged soils through chemical-physical combined method: A feasibility study

Abstract

Dredged soils are often considered as waste and pose significant environmental challenge. The objective of this study is to find the feasibility of utilizing dredged soil from Vizhinjam (MH soil) and Vallarpadam (CH soil) sites for land-filling applications through Chemical-Physical Combined Method (CPCM). Lime and fly ash were used as chemical stabilizers. The optimum percentage of the lime is determined as 6 (wt.%) and fly ash is 10 (wt.%) and 15 (wt.%) for MH and CH soil, respectively. The California Bearing ratio (CBR) increased by 55 and 60%, and Unconfined Compressive Strength (UCS) was enhanced by 61 and 53% for MH and CH soil, respectively. The chemically treated soil is then subjected to various physical treatments. The CPCM effectiveness was evaluated by determining shear strength by fall cone test. Curing by geobags enhanced 77 and 69% increase in shear strength for MH and CH soil, respectively, while vacuum preloading resulted in two times increase over the curing method. Among the physical methods, surcharge using geo-bags was found to be the most effective, as it improved the shear strength by 20–30% when compared to other approaches, making them suitable for reuse as an increase in shear strength contributes to the enhancement of bearing capacity.