Study on the Mechanical Behavior and Environmental Product Declarations of Road Base Layers Incorporating Anhydrous Calcium Sulphate

The adoption of circular economy principles and environmentally sustainable engineering is becoming increasingly prominent in civil engineering. Portland cement (PC) production alone is responsible for 8% of total annual CO2 emissions. Novel materials should possess good mechanical and physical properties while reducing CO2 emissions. This study analysed different mix designs for cement bound granular material (CBGM) road layers, partially replacing PC with anhydrous calcium sulphate (ACS), an industrial by-product. The objectives of the study include assessing mechanical performance through laboratory tests and analysing Environmental Product Declarations (EPDs) for each mix design. Two mix designs were examined: one with 3% ACS and 2% cement, and the other mix with 4% ACS and only 1% cement. Hydraulic binders used in the mixes included PC, Green Cement (GC), and ACS, with variations of aggregate types, natural and recycled. Innovative mix designs demonstrate comparable strengths to traditional CBGM layers. This paper aimed to analyse the environmental impacts using EPDs, comparing innovative mixes to those with 5% PC and 5% GC to identify environmentally friendly mixes with appropriate mechanical responses.