Impact Indexes Comparison Study Using Environmental Product Declarations (EPDs) on Innovative Cement Bound Granular Material Pavement Layers

In the last decades, the need to perform experiments with innovative new materials to be used in civil engineering and replace Portland Cement (PC) by embracing the concept of circular economy and environmentally sustainable engineering. PC production is responsible each year of 8% of the total CO2 emitted into the atmosphere, for this reason, it is vital to find valid alternatives to PC. Such innovative materials must not only have good mechanical and physical performances if comparedwith PC but also be obtainedwith very lowCO2 emissions. In this research innovative mix designs for road Cement Bound Granular Material (CBGM) layers were analyzed to evaluate the environmental impact, in which PC was partially replaced with Anhydrous Calcium Sulphate (ACS), a by-product of the hydrofluoric acid industrial production process. This paper analyzes the Environmental Product Declarations (EPD) of two main mixes, one with 3% of ACS and 2% of cement and the other one with 4% ACS and only 1% of cement. The selected mixes had already been studied from a mechanical and physical point of view. Laboratory and in situ tests ensured good mechanical and physical performances. This paper wanted to analyze the environmental impacts of such mixes using the EPD of each material forming the CBGM layers. For comparison, two reference mixes one with only 5% of PC and the other with 5% of Green Cement (GC) were also analyzed. The research aims to compare the blends and evaluate themix design with less environmental impacts. Twelve mix designs were considered, varying the type of hydraulic binders, that is PC, GC, and ACS and also the type of aggregates divided into Natural Aggregate (NA) and Recycled Aggregate (RA). The best design solution for the Global Warming Potential (GWP), which is one of the EPD parameters, was the mix incorporating 1% GC, 4% ACS and only RA.