Investigation of asphalt mixture strength at low temperatures with the bending beam rheometer

A new strength test method for asphalt mixture at low temperature is presented in this paper. The method uses a modified Bending Beam Rheometer (BBR), capable of applying loads at different rates. Two major factors that can significantly affect strength were analyzed: cooling medium and specimen size. Similar strength values were obtained in air and potassium acetate, and significantly lower values were obtained in ethanol. Preliminary investigation with sodium fluorescein indicates the fluorescing marker diffused in mixtures when ethanol was used. The failure distributions of BBR mixture beams and of larger beams were analyzed using histogram testing and size effect theory. Different Weibull moduli were obtained for BBR and larger beams, which indicates that BBR beams may be too small to capture the representative volume element (RVE) of the material.