Effect of water and cement content on the mechanical properties of cold recycled mixtures (CRM) with bitumen emulsion

Abstract

Cold recycled mixtures (CRM) treated with bitumen emulsion are innovative materials in road pavement construction industry which gained visibility in the last decades. They are produced at ambient temperatures thanks to the employment of bitumen emulsion, water and additional hydraulic binders. In this research, four CRM mixes are studied analysing the effect of two water contents and two cement dosages. The mechanical properties of the mixes were studied in terms of Indirect Tensile Ratio (ITR), Indirect Tensile Stiffness Modulus (ITSM) test and dynamic modulus test, after a curing period of 14 days. Moreover, results analysis is improved by images obtained at the scanning electron microscope (SEM). From the results, the presence of more water decreased the indirect tensile strength (ITS) in both dry and wet conditions, even if the water susceptibility was generally low (ITR > 80%). The PUNDIT measurements along curing highlighted the progressive increase of the dynamic modulus, which after curing was higher in the mixtures with cement. At the end, SEM images highlighted the effect of the water content in the dispersion of the bituminous phase, as well as the presence of cement hydration products.