Silt subgrade modification and stabilization with ground granulated blast furnace slag and carbide lime in areas with a recurring high groundwater

Deformation of wet silt subgrade is often problematic during pavements construction as well as under regular vehicular traffic loads. In order to create a sturdy and stable platform for pavement, soil modification and stabilization with combined ground granulated blast furnace slag (GGBS), carbide lime (CL) and ordinary Portland cement (OPC) was employed in this study. Mix proportion parameters of stabilized soils are analyzed by using the Taguchi's experiment design methodology for optimal design. Results show that OPC and GGBFS content play significant roles for the early strength and long-term strength of stabilized soil, respectively; whereas CL has an optimum content of 9% at the initial stages. Maximum unconfined compressive strength (UCS) of 1.61 and 2.32 MPa were achieved, respectively, at the optimum conditions of 4%GGBFS/6%CL//3.2%OPC at the curing age of 7 and 28 days. Splitting tensile strength (STS) increases rapidly with curing ages and reaches 0.45-0.48 MPa at the age of 56d. More dosage of carbide lime can help to the long-term strength. The GGBFS/CL/OPC-stabilized soil has a high durability. After 10 wet-dry cycles the strength loss ratio remains within 10%; after 10 freeze-thaw cycles the weight loss is below 8%. California bearing ratio (CBR) was conducted on the soil alone and the soil-stabilizer mixture. CBR ranging between 158 and 224 were obtained for the 7 days curing, whereas the silt typically has CBR less than 3.1 in its wet state. Field test was also conducted during construction using Dynamic Cone Penetrometer (DCP) to assess the strength of stabilized soil in situ. DCP test indicated that the strength development of GGBFS/CL/OPC stabilized subgrade is more rapid and the improvement of subgrade bearing capacity can facilitate an increase in compaction degree of subbase..