Evaluation of Engineering Properties of Rubberized Laboratory Mixes Containing Warm Mix Additives

Warm mix asphalt (WMA) refers to technologies which allow a significant reduction of mixing and compaction temperatures of asphalt mixes. From previous studies, it is observed that warm mix additives work in different ways, either in reducing the viscosity of the asphalt binder or allowing better workability of the asphalt mix at lower temperatures through volume expansion in the binder. If the technologies of WMA are incorporated into rubberized asphalt mixes, which are generally produced and compacted at higher temperature than conventional mixes, it is possible to reduce the mixing and compaction temperatures of rubberized mixes to those of conventional mixes. This paper presents a limited study that characterizes the engineering properties of crumb rubber modifier (CRM) mixtures containing warm mix additives. Six CRM mixtures (two of control mixtures and four of warm mixtures) were prepared using two aggregate sources and two additives: Aspha-min(R) and Sasobit(R). Evaluation of all mixtures included the following testing procedures: tensile strength ratio, asphalt pavement analyzer, resilient modulus, and resilient modulus after long-term oven aging. The results from this study showed that in general, there was no significant difference between the control and warm CRM mixtures for the properties evaluated in this study, indicating that the use of WMA technologies into CRM mixes is expected to have no negative effect on the mixture's engineering properties.