ABSTRACT
Road rehabilitation using cold recycling technology using stabilization with either foamed bitumen or bitumen emulsion as binders has grown significantly since 1995. At the outset this technology was implemented for an increase in the structural capacity of lightly to moderately trafficked roads. Invariably the pavement structures being rehabilitated included thin asphalt surfacings supported by granular or cemented bases. Over time, however, the technology has been applied to increasingly heavily trafficked roads. This has created a need for more reliable mix designs and structural designs for the bitumen stabilized materials. In addition, it has led to rehabilitation of pavements with thicker asphalt structures, sometimes resulting in 100% RAP being recycled.
This paper introduces the improved mix design methods for cold recycled materials. It addresses the key factors that influence the performance of bitumen stabilization including the mix components i.e. aggregate properties, bitumen characteristics, active filler type and moisture conditions, as well as compaction and engineering properties (Indirect Tensile Strength). Great strides have been made in the development of appropriate monotonic triaxial testing for performance evaluation of the final mix and the link of the shear parameters to pavement performance. The experiences of applying this mix design method to more than 500 different mixes used in international projects, has assisted in refining the procedures.
