Production temperatures and mechanical performance of rubberized asphalt mixtures modified with two warm mix asphalt (WM
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ORIGINAL ARTICLE
Production temperatures and mechanical performance of rubberized asphalt mixtures modified with two warm mix asphalt (WMA) additives Mahmoud Ameri Abolfazl Afshin
. Farzad Yazdipanah . Arash Rahimi Yengejeh .
Received: 16 March 2020 / Accepted: 24 July 2020 RILEM 2020
Abstract Studies show that warm mix asphalt (WMA) technology is a practical solution against the high production temperature of rubberized-asphalt (RA) mixtures. RA mixture containing WMA additive is considered as an eco-friendly technology contributing to noise reduction and performance optimization of asphalt mixtures. This study aims to introduce two organic WMA additives called slack wax (SW) and polypropylene wax (PPW) which are used to lower the production temperatures by reducing the viscosity of RA mixtures. Rotational viscosity (RV) as a common bitumen test (Equiviscous, ZSV, and S-ZSV methods), as well as tests related to mixtures including resilient modulus (Mr) and moisture susceptibility (TSR and MRR methods), were carried out on binder and mixture specimens. According to the results, 6% (by the binder’s weight) of both WMA additives reduced the mixing and compaction temperatures of the RA binder by about 20–25 C. Also, CRM and both WMA additives improved the stiffness of mixtures by increasing the resilient modulus (Mr). In terms of moisture susceptibility, although nearly all specimens could pass the minimum requirement of SCDOT, both WMA additives and CRM caused a reduction in ITS
M. Ameri (&) F. Yazdipanah A. Rahimi Yengejeh A. Afshin Department of Civil Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran, Iran e-mail: [email protected]
value of wet mixtures and final TSR value. MRR test results followed a similar trend, though resilient modulus was more sensitive to moisture damage compared to ITS. The results suggest that PPW and SW are suitable and cost-effective warm additives that can be used in combination with CRM in areas with hot climates and low precipitation. Nevertheless, additional experiments should be done to further validate the performance of CRM mixtures with these two warm additives. Keywords Warm mix asphalt Crumb rubber Waxy additives Mixing and compaction temperatures Resilient modulus Moisture susceptibility
1 Introduction 1.1 Background In recent decades, environmental considerations, energy-saving, and sustainable development have attracted attention in pavement engineering. As such, some new technologies and materials such as warmmix-asphalt (WMA) technology and crump-rubbermodified asphalt have been evolved in road surface construction to reduce environmental pollutions [1, 2]. Numerous studies have shown that reusing waste materials such as crump-rubber, which are finally
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disposed in landfills, not only diminish land consumption, but also prevent population growth of some dangerous insects [2]. Further, many investigations have revealed that mixtures containing crumb rubber modifier (CRM) provide superior mechanical pro
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