Evaluation of the influence of water on the rheological properties of mastic and asphalt mortars with different mineralogical composition

Abstract

This study evaluates the influence of the type of aggregate and the presence of water on the mechanical response of asphalt mastic and mortar. Samples of these materials were fabricated with a single asphalt binder classified with 60-70 (1/10 mm) penetration and three types of aggregates with a wide range of mineralogical compositions. The linear viscoelastic properties of the mastic and mortar were measured after subjecting them to three conditioning processes (i.e., dry, after 10, after 20, and after 60 days of being immersed in water, the 60 days were only evaluated in mastic). Additionally, the viscoelastic and chemical properties of the asphalt binder were evaluated under the same moisture conditions. The results show an increase in the dynamic shear modulus of the mastic and mortar with the conditioning time. This increase is partially due to the effects of water on the binder, but it was also found to be highly related to the type of aggregate. The results suggest that asphalt experiences chemical changes in the presence of water that caused an increase in the dynamic modulus, primarily due to oxidation processes occurring in the binder (i.e., increase in the carbonyl group of the asphalt). The same increase in dynamic modulus was observed in the asphalt mastic and mortars, where, in addition, aggregate chemistry was a determining factor in the dynamics and rate of change of the results. These results are important for understanding how water affects the mechanical properties of mortars and asphalt, and how the type of aggregate used affects moisture resistance. They also indicate how asphalt experiences chemical changes in the presence of water, and how chemistry is essential for understanding the dynamics and rate of change in the results.