Mechanical Properties of Warm Mix Asphalt Prepared Using Foamed Asphalt Binders

摘要

Warm mix asphalt (WMA) is a name given to a group of technologies that have the common purpose of reducing the viscosity of the asphalt binders. This reduction in viscosity offers the advantage of producing asphalt-aggregate mixtures at lower mixing and compaction temperatures, and subsequently reducing energy consumption and pollutant emissions during asphalt mix production and placement. WMA technologies reduce the asphalt binders viscosity through the addition of organic or chemical additives or by introducing cool water into the heated molten asphalt under controlled temperature and pressure conditions, resulting in so-called foamed asphalt binder. The latter has received increased attention in Ohio since it does not require the use of costly additives. In spite of the above-mentioned advantages of WMA mixtures, many concerns have been raised regarding the susceptibility of this material to moisture-induced damage and permanent deformation due to the reduced mixing and compaction temperatures used during WMA production. Therefore, this study was conducted to develop a laboratory procedure to produce WMA mixtures prepared using foamed asphalt binders (WMA-FA), and to evaluate their performance in comparison to conventional hot mix asphalt (HMA). Two aggregates (natural gravel and crushed limestone) and two asphalt binders (PG 64-22 and PG 70-22M) were used in this study. A laboratory scale asphalt binder foaming device called WLB10 was used to foam the asphalt binders.