Mechanical Response and Life Cycle Assessment of Pavement Base Layers Constructed with Soil-Cement Mix and Silica-Rich Additive

A laboratory study comprising unconfined compressive strength, durability, and California bearing ratio tests was conducted to evaluate the strength parameters of treated local soil with cement and silica-rich additive for possible application as a base layer of flexible pavements. The optimum dosages of cement and additive for the selected sandy soil were found to be 5.5% and 4%, respectively. Besides a significant enhancement in strength and durability properties due to the addition of additive, the durability characteristics of treated soil were found to improve by 75% at the optimum dosages. Large-scale model pavement studies were conducted to study the mechanical response of the proposed base layer consisting of cement-treated sandy soil considering both with and without additive. The response was compared with the conventional aggregate base layer. Improvement in the modulus parameter was quantified in terms of the modulus improvement factor (MIF) which is then used to design pavements with stabilized bases. MIF of cement stabilized soil bases with and without additive was found to be 13.9 and 12.7 with respect to unstabilized soil, while it was found to be 6.0 and 5.5 with respect to wet mix macadam. Finally, the life cycle assessment of a pavement crust for an expressway revealed that soil stabilized with cement and additive can reduce carbon emissions by 41% when compared to that of conventional aggregate base layer.