Development of warm in-place recycling technique as an eco-friendly asphalt rehabilitation method

Abstract

Cold In-place Recycling (CIR) has been widely applied in the world because it is easy to apply in the field at a low cost. However, it is not normally used as a surface layer because of its inconsistent quality due to an excessive amount of fine aggregates pulverized during the milling process. Hot In-place Recycling (HIR) can retain the original shape of the aggregates but it often produces a large amount of Volatile Organic Compounds (VOCs). Therefore, a third in-place recycling technique is introduced in this paper: Warm In-place Recycling (WIR). The WIR technique overcomes the limitations of both CIR and HIR techniques by lowering a heating temperature while adding a warm mix asphalt additive. The purpose of this WIR technology is to recycle old asphalt pavements in the field while reducing the amount of carbon dioxide generated during construction. A new WIR equipment is being developed for recycling asphalt pavements with significantly reduced amounts of emission. The emission controlled heating equipment reduces the emission by capturing the VOCs generated during the heating process, which would lead to the eco-friendly pavement recycling practices. To develop a new WIR additive, soybean oil was blended with Tetraethylenepentamine (TEPA) in the laboratory, where the formation of amide bonds was successfully achieved. To enhance the stiffness of the warm mix asphalt additive, the SBS polymer was also added to TEPA/Soybean-based WIR additive. Based on various binder and mixture tests, it can be concluded that TEPA/Soybean/SBS-based WIR additive was more effective in increasing both moisture and lower temperature cracking resistance than the WIR additive without SBS.