Environmental and economical assessment of earth-retaining walls for design optimisation

Abstract

The construction sector is one of the major contributors to global warming. This study aims to present a simplified method of evaluating environmental impacts through the embodied energy (EE) and carbon dioxide (CO2) emissions associated with earth-retaining walls (ERWs). The study considers a real case of slope-movement-caused fractures of a structure where four different types of ERWs were proposed to stabilise the slope. Moreover, an economical assessment of the selected ERWs is introduced. Recycled materials were also investigated as sustainable replacements of the natural materials. The results showed that concrete followed by steel production are the major contributors to carbon dioxide emissions and have the highest EE among all materials and stages by around 80% of the total amounts, regardless of the ERW design option. ERW construction emits 13.5–19.5 t of carbon dioxide and consumes 130–175 GJ of energy, while a reduction of 10–20% is achieved by using recycled materials. In general, pile walls were found to be the most environmentally friendly and economical option. Ultimately, the resulting carbon dioxide emissions and EE of all the ERW alternatives were verified and found to be well aligned with the carbon dioxide emissions and EE of the energy sources.