Engineering and leaching properties of asphalt binders modiﬁed with polyurethane and Cecabase additives for warm-mix asphalt application Nurul Aqilah Awazhar a , Faridah Hanim Khairuddin a,b , Suzielah Rahmad a , Syazwani Mohd Fadzil c , Hend Ali Omar d , Nur Izzi Md. Yusoff a,⇑ , Khairiah Haji Badri e a Smart and Sustainable Township Research Centre (SUTRA), Universiti Kebangsaan Malaysia, Selangor, Malaysia b Dept. of Civil Engineering, Universiti Pertahanan Nasional Malaysia, Kuala Lumpur, Malaysia c School of Applied Physics Studies, Universiti Kebangsaan Malaysia, Selangor, Malaysia d Dept. of Civil Engineering, University of Tripoli, Tripoli, Libya e School of Chemical Sciences, Universiti Kebangsaan Malaysia, Selangor, Malaysia highlights  The crystalline structure of the binders is unaffected by PU and Cecabase.  PU and Cecabase do not have a signiﬁcant inﬂuence on thermal transition of the B-B.  The concentrations of all heavy metals leached out are within the standards. article info Article history: Received 12 September 2019 Received in revised form 26 October 2019 Accepted 24 November 2019 Keywords: Polyurethane Warm-mix asphalt Consistency Adhesion Thermal Leaching abstract Asphalt binders have been modiﬁed with various additives and modiﬁers as an effort to fulﬁl the demand for high-performance pavements. Therefore, this study aims to investigate the engineering and leaching properties of 60/70 penetration grade asphalt binder modiﬁed with polyurethane (PU) and Cecabase addi- tives for warm-mix asphalt (WMA) application. Measurements of the physical properties of unmodiﬁed and modiﬁed asphalt binders were made via penetration, softening point, ductility and viscosity tests. The binder-aggregate adhesivity was established by performing the Vialit test while X-Ray Diffraction (XRD) analysis was conducted to determine crystallinity of the binder. Differential Scanning Calorimetry (DSC) was used to determine thermal behavior of the asphalt binders. Synthetic precipitation leaching procedure (SPLP) test was carried out to determine the mobility of organic and inorganic ele- ments present in the binder. PU as modiﬁer and Cecabase as the WMA additive-enhanced binder stiffness. In contrast to Cecabase, the addition of PU increased viscosity of the binder at varying temperatures. PU also enhanced the interfacial adhesion between the binder and the aggregates. The XRD patterns showed that the incorporation of PU and Cecabase has no inﬂuence in the crystalline structure of the asphalt bin- ders. Both PU and Cecabase have the ability to improve the workability of the binder at low temperature. The incorporation PU and Cecabase to the asphalt binder showed insigniﬁcant shift of the T g and T m . SPLP test results indicated that the amount of heavy metals leached out from the asphalt binder samples have no adverse effect on the environment and also did not exceed the standard for drinking. Ó 2019 Elsevier Ltd. All rights reserved. 1. Introduction Warm-mix asphalt (WMA) technology is fast gaining popularity in the hot-mix paving application by virtue of its lower mixing and compaction temperatures as well as reduced emission of incidental fumes and odours [1]. WMA is essentially similar to hot-mix asphalt (HMA) since the aggregates and asphalt binder of WMA have to be heated in order to achieve suitable mixing and worka- bility [2]. The failure and performance of the pavements con- structed utilizing WMA technologies were compared to those of HMA with regard to moisture damage, rutting, stripping, cracking, compaction level, modulus, etc. [3]. Capitao et al. [4], Rubio et al. [5], Kheradmand et al. [6], Abdullah et al. [7], Xu et al. [8], Mohd https://doi.org/10.1016/j.conbuildmat.2019.117699 0950-0618/Ó 2019 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail addresses: hanim@upnm.edu.my (F.H. Khairuddin), suzielah@live.com. my (S. Rahmad), syazwanimf@ukm.edu.my (S.M. Fadzil), hend.omar@uot.edu.ly (H. A. Omar), izzi@ukm.edu.my (N.I. Md. Yusoff), kaybadri@ukm.edu.my (K.H. Badri). Construction and Building Materials 238 (2020) 117699 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat