摘要: |
In this project, a comprehensive study was conducted to evaluate the laboratory performance of foamed WMA mixtures with regard to permanent deformation, moisture-induced damage, fatigue cracking, and low-temperature (thermal) cracking; and compare it to traditional HMA. In addition, the workability of foamed WMA and HMA mixtures was evaluated using a new device that was designed and fabricated at the University of Akron, and the compactability of both mixtures was examined by analyzing compaction data collected using the Superpave gyratory compactor. The effect of the temperature reduction, foaming water content, and aggregate moisture content on the performance of foamed WMA was also investigated. Furthermore, the rutting performance of plant-produced foamed WMA and HMA mixtures was evaluated in the Ohio University (OU) Accelerated Pavement Load Facility (APLF), and the long-term performance of pavement structures constructed using foamed WMA and HMA surface and intermediate courses was analyzed using the Mechanistic-Empirical Pavement Design Guide (MEPDG). The laboratory test results revealed comparable resistance to permanent deformation, moisture-induced damage, and fatigue cracking for foamed WMA and HMA mixtures. However, the HMA mixtures had significantly higher ITS values at 14oF (-10oC) and comparable failure strains to the foamed WMA mixtures, which indicates that the traditional HMA mixtures have better resistance to low-temperature (thermal) cracking. The laboratory tests conducted to evaluate the effect of the temperature reduction, foaming water content, and aggregate moisture content revealed that the performance of foamed WMA mixtures prepared using 30oF (16.7oC) temperature reduction, 1.8% foaming water content, and fully dried aggregates was comparable to that of the HMA mixtures. However, reducing the production temperature of foamed WMA resulted in increased susceptibility to permanent deformation and moisture-induced damage. In addition, produci |