Establishing a Threshold Sustainability Index for a Geotechnical Construction

Sustainability studies in geotechnical engineering have focused on life cycle assessment (LCA) of materials and construction processes to quantify the environmental and socio-economic impacts of construction. However, in the absence of a threshold or allowable value depicting the degree of sustainability, a comprehensive assessment of the system sustainability is infructuous. This paper demonstrates a framework to establish a threshold sustainability index for a geotechnical construction. The approach is illustrated through a subgrade stabilization project for a low-volume road (LVR) in Arlington, TX, involving treatment with lime and cement. The subgrade soil was an expansive (high plasticity) clay, having a low to moderate soluble sulfate concentration. The methodology incorporates a multi-criteria assessment of resource use, environmental impact, and socio-economic consequences. The framework designates the threshold sustainability index (I_T-Sus) for a particular project, besides providing a pictographic representation of the different sustainability elements.