Abstract
This paper presents results stemming from a comparative experimental analysis of two warm-mix asphalts (WMA) and a dense-graded hot-mix asphalt (HMA). In order to evaluate asphalt mixture behavior, physical and rheological tests were conducted, including tests on resilient modulus, resistance to moisture-induced damage, resistance to fatigue and resistance to permanent deformation. Samples studied were subjected to short (STOA) and long-term (LTOA) aging. As far as asphalt mixture composition is concerned, the same particle size distribution and coarse aggregate were employed for both mixture types. The control HMA mixture was produced with AC 60-70, and the WMAs used the same asphalt cement modified with two chemical additives (Rediset WMX® and Cecabase RT®). The modified mixtures exhibited better resistance to permanent deformation, aging and moisture-induced damage (versus the control mixture). Likewise, WMAs generally saw increased fatigue resistance under controlled-stress loading, which rheological characterization showed is mainly attributable to binder additives and their concomitant modifications.
Highlights
BackgroundAsphalt mixtures are described in terms of the temperatures employed for their production in specialized asphalt plants
This process enhances aggregate coverage, thereby improving the mixture’s binding capacity upon compaction. Translating their application to warm-mix asphalts (WMA) production required the use of synthetic zeolites or other chemical materials, which are mixed with the coarse aggregate to foam the asphalt
The first chemical additive used was Rediset WMX, a water-free chemical additive produced by Akzo Nobel; it contains a combination of organic additives and surfactants (Anderson et al, 2008; Hamzah et al, 2013)
Summary
Asphalt mixtures are described in terms of the temperatures employed for their production in specialized asphalt plants. Chemical and organic additives are mixed with the asphalt before aggregate-addition during mixture production. Employed for over 50 years to produce CMAs, asphalt foaming techniques consist of adding small quantities of water to asphalt at high temperatures (prior to mixture with aggregates). This process enhances aggregate coverage, thereby improving the mixture’s binding capacity upon compaction. Translating their application to WMA production required the use of synthetic zeolites or other chemical materials, which are mixed with the coarse aggregate to foam the asphalt. Doubts remain regarding the cost-benefit relation—in technical, economic, and environmental terms—associated with WMA technology
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