Evaluation of energy requirement and greenhouse gas emission of concrete heavy-duty pavements incorporating high volume of industrial by-products

Abstract

This study evaluates the effects of high percentages of different by-products, including blast furnace slag (BFS) and fly ash (FA), on the structural performance, energy requirement and environment impacts of a concrete heavy-duty pavement (HDP) at various curing temperatures. The results of the structural performance indicate that HDP containing up to 70% BFS and HDP containing 30% FA can be comparable in controlling the HDPs designed for highways and airports. Moreover, the results of the environmental impact assessment indicate that the synergy of the by-product and warm water can reduce the energy requirement and CO2 footprint by 5.77%–56.54% and 8.16%–55.5% for the highway and airport HDPs, respectively. Although the elevated curing temperature improves the structural performance and sustainability of the concrete pavements, any delay in concrete production increases energy consumption accordingly. Moreover, a new parameter (∇TE), which is the time gradient per unit energy consumption developed based on the Laplace transformation, is proposed to characterize the effect of the time delay in concrete production. This parameter indicates that the time required for a unit energy consumption (1 TJ) decreases by 50%, as the curing temperature increases. In conclusion, analysis of the structural design, carbon footprint, and the results of ∇TE indicate that 35 °C can be proposed as the optimum water curing temperature for the HDP incorporating by-products.