The influence mineral additions on the failure properties of bitumen emulsion mortars

Abstract

The use of both cold asphalt and cold recycled asphalt mixtures produced with bitumen emulsion is constantly increasing. The failure properties of these low-energy materials are normally improved by using mineral additions or active fillers. These additions are a key component of the bituminous mortar, which binds the coarse aggregate fraction of the mixture. The objective of the present study is to investigate the evolution of the failure properties bitumen-emulsion mortars obtained by using three different types of additions: Portland cement (active filler), hydrated lime and calcium carbonate (inactive filler). The mortars were prepared with standard sand and a fixed bitumen/addition rate. Cylindrical samples were compacted with a shear gyratory compactor, the selected procedure also allowed evaluating the effect of the different additions and water content on workability. The indirect tensile strengths were measured after 7, 14, 28 and 100 days of curing in two conditions: sealed (i.e. no evaporation) and unsealed, at 50 % relative humidity. Each bituminous mortars was also characterized in terms of low temperature fracture resistance. Results showed the influence of the mineral additions on the emulsion breaking and the different curing conditions allowed highlighting the impact of both evaporation and cement hydration on strength and stiffness evolution.