Long-term rutting and stripping characteristics of foamed warm-mix asphalt (WMA) through laboratory and field investigation

Injected water and low production temperature during foaming make foamed warm-mix asphalt (WMA) more prone to rutting and stripping. Though foamed WMA is reported to exhibit higher rutting and stripping potentials in its early life, it is not clear how these characteristics change with field experienced aging and densification. This study evaluates long-term rutting and stripping potentials of both field (five years experienced) and short-term aged laboratory compacted foamed WMA specimens. In addition, field rut data have been evaluated through Mandli's pavement profile scanner. It is noted that field WMA pavements were surfaced with 15 mm of rubberized open-graded friction courses (ROGFC). Laboratory tests: Hamburg-wheel tracking (HWT) and indirect tensile strength (ITS), have been conducted on selected specimens. Two different moisture conditioning methods have been employed on ITS test specimens. A newly developed HWT test analysis has been performed to eliminate the existing limitations of the conventional method of HWT analysis. The study found that densification and long-term field aging contribute to improvement in rutting and stripping characteristics.