Uncertainty and Sensitivity Analysis of Environmental Impacts in Flexible Pavement Construction Using Alternate Industrial Waste

Uncertainty and sensitivity analysis are two important techniques used to assess the robustness and reliability of life cycle assessment results and to identify key drivers of environmental impacts. Recently many industrial wastes have been found to be sound alternatives in pavement construction preferably as base and subbase layer. In the present study, environmental sustainability of a flexible pavement of 1 km stretch constructed with crushed coalmine overburden waste rock, red mud—slag blend, and conventional natural aggregate is compared. Further, the detailed uncertainty analysis of each alternative is done using Monte-Carlo simulation to identify the sources, quantify the degree of uncertainty and assess its impact on the final results. The identified critical sub processes were considered for the sensitivity analysis, to identify the input parameters that have the greatest influence on the LCA results, to prioritize data collection efforts, and to guide decision making. The analysis results are indicative of the fact that use of industrial waste is more sustainable than the use of natural aggregate considering the emission caused in the waste production as collateral of the coal, aluminium, and steel industry. The emission caused during the processing of raw and transportation of these waste for use in base and subbase are found to be most critical and the degree of uncertainty associated is maximum for carcinogenics, non carcinogenics, and ozone depletion. However, the magnitude of emissions in these categories are negligible. Hence, uncertainty can be neglected.