Life cycle assessment (LCA) of MSE wall vis-à-vis conventional retaining wall: a comparative study

This article presents the phases in a life cycle assessment (LCA) methodology and gives the design approach for two types of retaining walls namely, conventional reinforced concrete retaining wall (cantilever type) and a mechanically stabilised earth (MSE) wall using paragrid 100/05 as reinforcement. A comparative study was done for both retaining structures with three different heights of wall, such as 3 m, 5 m and 7 m. All the retaining walls are designed using a FEM-based GEO5 software and are checked for their stability, keeping the design economical. Later, GaBi software was used to evaluate the environmental impacts using eight mid-point category indicators, such as cumulative energy demand, global warming potential, acidification potential, water use, ozone depletion potential, eutrophication potential, land use, and particulate matter. Later, an evaluation based on economic point of view was also carried out. Potential impact on environment indicated that, the global warming potential, acidification potential, and fine particulate formation are influenced primarily by concrete and steel production (due to their raw mineral extraction, cleaning and refining, and energy invested for processing), as well as by the fuel used for transportation, and on-site machinery. It was found that, MSE wall is more environment friendly than conventional reinforced concrete cantilever retaining wall, as it resulted in 24% lower environmental impact for a 3 m height wall and 60% lower environmental impact for 5 m and 7 m height walls. Economic evaluation of both retaining structures revealed that, the MSE wall is proved to be approximately 42% less in cost for 3 m height wall and about 70% less cost for 5 m as well as 7 m height walls. In terms of environmental and economic aspects, MSE wall is found to be more sustainable than the cantilever retaining wall over its full life cycle.