Efficacy and Sustainability Benefits of Innovative Materials for Stabilization of Problematic Pavement Subgrades

Abstract: Soil stabilization is a prerequisite for constructing pavements over problematic soils so that the likelihood of subsequent damage and excessive maintenance is reduced. Traditional stabilizers such as ordinary Portland cement (OPC) tend to have a high environmental carbon footprint and may be unsuitable in coastal and high-sulfate environments. Consequently, innovative solutions based on alternative materials such as recycled concrete aggregate fines and geopolymers are gaining traction. In this paper, we evaluate the unconfined compressive strength (UCS) improvement and life cycle sustainability of two stabilization methods. In the first study, a low plasticity soft clay was treated using Portland limestone cement (PLC) and recycled concrete aggregate fines (fRCA). The unconfined compressive strength (UCS) of soil specimens treated using PLC and varying quantities of fRCA (15% and 30%) was 2884 kPa and 3060 kPa. In comparison, the baseline UCS of soil specimens treated using PLC was 3080 kPa. The life cycle sustainability assessment (LCSA) of PLC + fRCA treatment concluded that the environmental emissions were reduced by 20% and overall costs were reduced by 5-10% relative to the baseline treatment. In the second study, a salt-rich high plasticity clay was treated using geopolymers. The UCS of the geopolymer-treated specimens ranged from 580 kPa to 1930 kPa. The LCSA of geopolymer treatment concluded that the environmental emissions were reduced significantly relative to the traditional treatment. In a nutshell, the study demonstrated that the utilization of innovative materials for the stabilization of subgrades is a viable option with significant environmental benefits.