Application of Anhydrous Calcium Sulphate in Cement Bound Granular Pavement Layers: Towards a Circular Economy Approach

The reported research concerns about Anhydrous Calcium Sulphate (A.C.S.) potential applications in Cement Bound Granular Material (C.B.M.) pavement layers. A.C.S. is a secondary byproduct deriving from industrial production processes. This research aims to find the best C.B.M. mix, in terms of mechanical performances, in which A.C.S partially replaces Portland cement. A total of 5 different mixes were studied, with variable percentages of cement ranging between 1% and 3% and A.C.S. ranging between 0% and 4%. On each of the prepared specimens, compression strength and indirect tensile strength tests were performed. A trail pavement, under construction, based on the result of the laboratory tests, allows establishing the performances in working conditions. The preliminary results are encouraging: good mechanical performances, if compared to traditional C.B.M. incorporating only Portland cement, can be observed when the overall binder content in the mix (given by the sum of cement and A.C.S. percentages) is kept in the range of 5%. There is a need to study new applications for byproducts to achieve sustainable development towards a circular economy strategy in the construction sector.