Evaluation Of Warm Mix Additives For Use In Modified Asphalt Mixtures

Evaluation of Warm Mix Additives for Use in Modified Asphalt Mixtures

The intention of this research effort is to evaluate the use of warm mix additives with typical polymer-modified and terminal blend tire rubber asphalt mixtures from Nevada and California. The research effort is broken into three phases that are intended to evaluate the impacts of warm mix additives with typical polymer-modified and terminal blend tire rubber asphalt mixtures from Nevada and California: moisture damage, performance characteristics, and mechanistic analysis. In Phase I of this research effort, mixture resistance to moisture damage was evaluated using the indirect tensile test and the dynamic modulus at multiple freeze-thaw cycles. Laboratory testing was conducted to address the following: (1) the impact of warm mix additive and reduced production temperatures on the moisture damage resistance of asphalt mixtures, (2) the impact of residual aggregate moisture on the moisture damage resistance of WMA mixtures, (3) the impact of warm mix additives on the moisture damage resistance of anti-strip treated WMA mixtures, and (3) the impact of long-term aging on strength gain and the moisture damage resistance of WMA mixtures. A total of one aggregate source, four warm mix asphalt technologies (Advera, Sasobit, Revix and Foaming) and three asphalt binder types (neat, polymer-modified and terminal blend tire rubber modified asphalt binders) typically used in both Nevada and California are being evaluated in this study. This thesis will only summarize the test results and findings of the Phase I of the study for two warm-mix additives: Advera and Sasobit. The evaluation of the other two technologies (i.e. Revix and Foaming) as well as the Phase II testing are still in progress and have not been completed.

Evaluation of Warm Mix Asphalt Additives for Use in Modified Asphalt Mixtures

Evaluation of Warm Mix Additives for Use in Modified Asphalt Mixtures

The purpose of this research effort was to evaluate the use of warm-mix additives with modified (polymer-modified and terminal blend tire rubber) asphalt mixtures from Nevada and California. This research was completed in two stages: Sasobit and Advera were evaluated in first stage while Evotherm and Foaming were evaluated in second stage. The three main components of the experimental plan include: evaluation of mixture resistivity to moisture damage, pavement performance characteristics of the mixtures, and mechanistic analysis of the mixtures for simulated flexible pavement. The moisture resistivity of all mixtures were checked by Indirect Tensile Strength (ITS), and Dynamic Modulus (E*) tests. Dynamic Modulus Ratio (ECR) and Tensile Strength Ratio (TSR) were computed at multiple Freeze-Thaw (F-T) cycles for further evaluation of moisture sensitivity of mixtures. Flow Number (FN) and Flexural beam fatigue tests were conducted to evaluate the performance characteristics of WMA additives/technology. The terminal blend tire rubber-modified binder with lime treatment works effectively in resisting moisture damage, rutting, and to significantly-reasonably improve the fatigue life of the WMA Evotherm, Foaming, Advera and Sasobit mixtures. Hence, it is the best solution for the design and construction of sustainable asphalt pavements. The use of terminal blend rubberized asphalt binder is an excellent and economical selection in reducing tire waste and environmental impacts.