Preliminary Laboratory Evaluation of Methanol Foamed Warm Mix Asphalt Binders and Mixtures

Abstract

The use of warm mix asphalt as an environmentally friendly alternative to hot mix asphalt is quickly building credibility and notoriety. Many technologies are being investigated that allow asphalt to be produced at a lower temperature. One warm mix technology currently being researched is the use of foamed asphalt binder. The foaming process expands the binder temporarily as injected water boils and expands. One limitation of this process is the minimum temperature at which asphalt can be foamed. The objective of this study was to conduct a preliminary study on the performance of methanol foamed asphalt binders and mixtures to reduce production temperature at a high level. According to this, the workability, rutting potential, aging performance, and moisture susceptibility were investigated. The results suggested that the methanol foamed asphalt had visibly better workability than control binder by lowering the mixing temperature by as high as 40°C. However, the rutting potential and moisture susceptibility may be compromised due to the lower aging and weak asphalt-aggregate interaction under low mixing and compaction temperatures. The mass loss results indicated that there was no methanol remaining in the binder after rolling thin film oven (RTFO) aging. Anti-stripping additives were recommended to be used for the methanol foamed asphalt mixtures to improve resistance to moisture damage.