Influence of reclaimed asphalt on mechanical characteristics of cement-bitumen treated materials

Cold recycling techniques have become one of the main sustainable solutions in road construction and maintenance. The use of reclaimed asphalt (RA) as a constituent material for bound mixtures offers two main advantages: it eliminates problems concerning disposal and it allows natural resources to be preserved. RA must be considered a real construction material and it has to be accurately selected for any specific use. Currently, engineers and technicians are eager to exploit the use of RA in construction and maintenance planning, but the lack of a clear understanding of RA effects on the performance of the mixture requires a detailed investigation. Among the most widespread recycled mixtures, the use of cement-bitumen treated materials (CBTM) for subbase courses has rapidly increased over the last 10 years. In particular bitumen can be introduced in the form of foam or emulsion and the aggregate blend may contain RA. This paper deals with the influence of RA content on the mechanical characteristics of CBTM. Several mixtures were produced by combining different dosages of binders (cement and bituminous emulsion) and RA contents. The behavior of recycled mixtures was evaluated and compared in terms of indirect tensile strength, water sensitivity and stiffness modulus. In addition, the effects of temperature on the stiffness properties were investigated. The findings offer good prospects for increasing the use of RA and encourage administrations to employ this material as an effective construction solution.