Experimental study of bitumen emulsion–cement mortars: mechanical behaviour and relation to mixtures

Cold bitumen emulsion mixtures are ecofriendly materials for road pavement construction. Portland cement and other supplementary cementitious materials are added to the mixtures to improve their performance. In bitumen emulsion–cement (BEC) mixtures, the two binders affect the mechanical behaviour and the curing process. In this research, BEC mixtures are considered as multiphase composite materials consisting of a mortar matrix and coarse aggregate inclusions. The main objectives are to identify the composition of BEC mortar phase and to compare mixtures and mortars throughout the curing process. Starting from two BEC mixtures containing 80% reclaimed asphalt, eighteen mortars were manufactured by changing their water and air voids content. Then, two design composition were selected to analyse the curing process by monitoring indirect tensile strength (ITS), indirect tensile stiffness modulus (ITSM) and moisture loss. Results showed that the short-term ITS of mortars (1 day of curing) increased by reducing their water and their air voids content. During curing (from 1 to 28 days), the mechanical properties (ITS and ITSM) of mixtures and mortars increased in a similar way. Unique relationships were identified between mortar and mixture properties, regardless of bitumen to cement (B/C) ratio, curing time and curing condition. In terms of predictive behaviour, the design composition slightly underestimated mixture stiffness and overestimated mixture strength.