A comparative life cycle assessment of innovative highway slope repair techniques

Abstract

Abstract The study evaluates the environmental performances of innovative and conventional remedial techniques to repair shallow highway slope failures. A comparative life cycle assessment (LCA) was performed, adopting a cradle-to-site system boundary, employing a cut-off approach for a hypothetical slope. Slope stabilisation systems under assessment include: granular rock fill replacement, planting live willow poles, fibre reinforced soil, and electrokinetic geosynthetics (or electro-osmosis). The functional unit of analysis was defined as the ability of each technique to initially stabilise 1 m2 of failed slope. Assessments explored the impacts of slope failures at two standard depths, and for a range of transport scenarios. Results (expressed in kgCO2e/m2 of failed slope) indicate that at both failure depths, across all transport scenarios, the greatest environmental impact was generated from the granular rock fill. The least impactful technique was willow pole planting, closely followed by electrokinetic geosynthetics. Relative to the granular rock fill replacement, the impact of the willow pole technique was about 7–8%, electrokinetic geosynthetics is 8–13% and the impact from fibre reinforced soil technique ranged from 19 to 32% of the control. In addition, the transportation of materials and equipment was the single largest contributor of carbon dioxide emissions.