Compressibility of solidified dredged marine soils (DMS) by mass treatment

Dredged marine soils (DMS) are normally disposed offshore. This soil is relatively poor and weak in terms of strength. Hence, the DMS could be strengthened up by solidification. In this study, waste granular materials (WGM) such as coal bottom ash (BA) and palm oil clinker (POC) were utilized as additional binder to cement. The purpose of this research is to determine the one-dimensional compressibility and time-dependent compressibility characteristics of DMS with mass solidification using BA and POC. The objectives were achieved through laboratory tests namely laboratory fall cone penetration, vane shear and oedometer tests. Based from the physical test results, DMS sample in Kuala Kedah was classified as low plasticity silt (ML). Proportioned samples of 10, 15 and 20 % of cement and 50 and 150 % of WGM were subjected to one-dimensional oedometer test. The homogeneous samples of 10C100 and 15C50BA/WGM resulted with the considerable range of final settlement (Fs) 17-24 % at 800 kPa, which equivalent to the effect of that cemented sample of 20C with Fs of 18.5 %. Sample 10C100POC has resulted with Cc value of 0.013 which is less compressible than sample 15C50POC with Cc value of 0.016. This proven that the compressibility of homogeneous-POC sample was governed by soil-skeleton structure and pozzolanic reaction induced by high SiO2 contents. The time for end of primary consolidation (t100) for samples of 10C, 15C and 20C which in range of 9-13 minutes have hastened the full dissipation of pore water. This can be further acknowledged with the coefficient of consolidation (Cv), where cement-induced sample has improved the Cv in range of 2-4 m2/year than the untreated soil of 0.15 m2/year. In term of hydraulic conductivity (k), the homogeneous sample has resulted as less permeable which was possibly due to sealed drainage path of clay in the soil's inter-void spaces. Thus, outcomes from this study suggested that DMS admixed with cement and WGM could be reused as an alternate backfill material for land reclamation and clay liner for landfills with improved settlement and consolidation rate