A number of warm-mix asphalt (WMA) technologies are used to reduce the temperature at which the asphalt mixtures are produced and compacted, apparently without compromising the performance of the pavement. The main objective of this study is to determine whether the use of an innovative wax-based LEADCAP WMA additive influences the performance of the asphalt mixture, which is produced and compacted at significantly low temperatures. The WMA pavement using LEADCAP additive (WMA-LEADCAP) along with a control HMA pavement was evaluated with respect to their performances of rutting resistance, crack resistance, and viscoelastic property based on the laboratory dynamic modulus test, indirect tensile strength test, and in-door accelerated pavement test (APT) results. With the limited data carried out, the LEADCAP additive is effective in producing and paving asphalt mixture at approximately 30°C lower temperature than a control HMA mixture, and the performances of WMA-LEADCAP pavement are comparable to a control HMA pavement.

No abstract

Conventional stone mastic asphalt (SMA) is being increasingly used in highways and expressways because it provides high rutting resistance, good skid resistance, and noise reduction for heavily trafficked roads. However, the conventional SMA mixture requires high mixing and compacting temperatures to create a suitable coating between the polymer-modified asphalt and large size of aggregate. Warm-mix asphalt (WMA) technology is being extended to provide significant economic benefits when applied to heat sensitive mixture, such as polymer-modified mixture, to reduce mixing and compacting temperatures. In this study, the performance characteristics of SMA–WMA mixture using new polyethylene wax-based WMA additive were evaluated against the conventional SMA mixture without additive, in terms of the moisture susceptibility, viscoelastic properties, rutting resistance at high temperature, fatigue resistance, and crack resistance at low temperature. The mix design was carried out in the laboratory for the conventional SMA mixture, and a similar composition was adopted for the SMA–WMA mixture (with the incorporation of 1.5 % WMA additive in the asphalt binder weight), in order to evaluate the influence of the performance characteristics of the resulting SMA mixture. Drain-Down and Cantabro test results of SMA–WMA mixture meet the requirement of the relevant criteria. Compared to the conventional SMA, the mixtures containing WMA additive show superior performance in moisture susceptibility, rutting resistance at high temperature, fatigue resistance at intermediate temperature, and crack resistance at low temperature. Therefore, this implies that the WMA additive is effective in reducing the production temperature, without compromising the performance of the SMA–WMA mixture.

Several warm-mix asphalt (WMA) technologies have been developed and implemented worldwide. Because of the reduced production and compaction temperatures of WMA mixtures, WMA technology can reduce energy consumption, carbon dioxide emission, and asphalt oxidation as well as extend the paving season, increase hauling distance, and create a better working environment. A wax-based WMA additive called low-energy and low–carbon-dioxide asphalt pavement (LEADCAP), has been developed by the Korea Institute of Construction Technology and Kumho Petrochemical and is the first WMA additive developed in South Korea. This paper introduces the characteristics of this newly developed WMA additive and presents the performance evaluation of WMA with LEADCAP. To evaluate the performance of the WMA mixture with LEADCAP additive, the Superpave® mix design, moisture susceptibility test, and mechanical test were performed. Common hot-mix asphalt and a WMA mixture with Sasobit additive were also evaluated for comparison. Sasobit is also a wax-based additive and is well-known. Mechanical tests included the dynamic modulus test, the direct tension fatigue test, and the triaxial repeated loading permanent deformation test. From the limited data obtained in this study, it was concluded that LEADCAP could be effectively used in WMA mixtures and that the performance of WMA with LEADCAP could be expected to be comparable to that of hot-mix asphalt and WMA with Sasobit additive.

This paper presents a simplified viscoelastic continuum damage material model for the evaluation of moisture susceptibility of asphalt concrete. The model is based on cyclic direct tension testing and layered visco elastic analysis. The visual stripping inspection afforded by digital imaging analysis is also proposed as an intuitive and straightforward method for moisture susceptibility evaluation. These methods were applied to a Superpave ® 19mm hotmix asphalt mixture and corresponding warm mix asphalt mixtures modified by a polyethylene waxtype additive with and without an antistripping agent. The fatigue life predicted by the sim plified viscoelastic continuum damage and layered viscoelastic analysis models had a strong correlation with the percentage of stripping deter mined from specimen surfaces that were fractured during cyclic direct tension testing of the hotmix and warmmix asphalt mixtures with various asphalt contents. In addition, a polyethylene waxtype additive combined with an antistripping agent was found to provide a longer fatigue life and less stripping than a pure polyethylene waxtype additive. The findings from this paper should provide guidance to agencies and material engineers in developing asphalt binder modifiers that lengthen the fatigue life of pavements and reduce moisture susceptibility.