Mechanical Behaviour of Cold Recycled Asphalt Mixtures for Binder Courses Produced with Bitumen Emulsion and High Strength Cement
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Cold recycled asphalt mixtures (CRAM) are sustainable solutions for maintenance and rehabilitation of road pavements. Notwithstanding the environmental benefits, CRAM may exhibit lower performances compared to traditional hot mix asphalt. Besides, CRAM require a curing period to reach their long-term properties, and thus, they are usually employed in base courses. This work investigates the mechanical behaviour of CRAM with bitumen emulsion and high strength cement to verify if they are suitable for binder courses. Six CRAM were produced using 80% of reclaimed asphalt, modified emulsion and two high strength cement: sulfo-aluminous and Portland-slag cement. For comparison, two additional mixtures were produced using traditional emulsion. The CRAM had an emulsion content of 4.2% or 5.0%, and residual bitumen to cement ratio of 1.0 or 1.2. After curing periods from 6 h to 1 year, the indirect tensile stiffness modulus (ITSM) and indirect tensile strength (ITS) were assessed. Their thermal sensitivity was evaluated as well, measuring ITSM at different temperatures. Results indicate that high strength cement leads to satisfactory mechanical behaviour in the long-term. Compared to Portland-slag cement, sulfo-aluminous cement increases the rate of development of ITS and ITSM in the early stage of about 50% and 25%, respectively.
KeywordsCold recycling Reclaimed asphalt High strength cement Bitumen emulsion Curing Thermal sensitivity
The activity presented in the paper was funded by Italcementi–HeidelbergCement Group. Furthermore, the Authors desire to thank Valli Zabban S.p.A. and Società Cooperativa Braccianti Riminese Companies for providing the bitumen emulsion and the RA aggregate.
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