Field Performance of Foaming Warm Mix Asphalt Pavement

Water-containing and water-based foaming warm mix asphalt (WMA) technologies have been widely used in recent years but their long-term field performance is scarcely documented. This paper summarizes the field performances of six water-containing foaming and 10 water-based foaming WMA pavements across the United States and compares them with corresponding hot mix asphalt (HMA) pavements. Two series of field distress surveys were conducted to measure wheel-path longitudinal cracking, transverse cracking, and rut depth. Field cores were extracted to measure the in-place air void content, aggregate gradation, and asphalt content. The volumetric properties and field performance of foaming WMA and HMA control pavements were evaluated. The foaming WMA pavements showed slightly higher in-place air void (i.e., lower in-place density) than the HMA pavements. It was also found that the foaming WMA pavements in general had comparable or more wheel-path longitudinal cracking than the HMA pavements. The long-term field performance of foaming WMA pavements for transverse cracking and rutting were found to be similar to control HMA pavements. The study also reinforced the importance of in-place air void and asphalt content, finding that slightly higher asphalt content and lower in-place air void content may be beneficial for long-term resistance to cracking of asphalt pavements. As a result of the findings, the optimal pavement maintenance time was estimated to be four to five years since paving for full-depth pavement projects.