Alternative Modified Binders for Mastic Asphalt Layers

The ever-increasing requirements on quality and life-span of asphalt layers present a reasonable motivation to explore new approaches and technologies. For many years, the technical options have included modification of regular paving grade bituminous binders. This paper focuses on the possible use of bituminous binders used; both activated and chemically improved by selected modifiers, in mastic asphalt as well as on their potential beneficial effects on selected parameters of the mixtures tested. The modification of reference paving grade bitumen 20/30 involved micromilled (pulverized) recycled crumb rubber as well as a new generation of synthetic waxes or even combination of the two types of additives. Potential benefit can be seen in the improved deformation characteristics and in the possibility to reduce the manufacturing temperature including potential improvements in mix workability. The paper presents the experimental assessment in the form of the indentation test, compression strength test, 3-point bending beam strength test, stiffness and creep characteristics. The properties of mastic asphalt mixtures are complemented by parameters of the bituminous binders applied (complex modulus, viscosity etc.).