Warm mix asphalt (WMA) for rapid construction in airfield pavement

Abstract

Warm-mix asphalt (WMA) is commonly mixed and compacted 15°C to 30°C below that of conventional hot mix asphalt (HMA). The lower production temperature of WMA is expected to give an advantage of a lower cooling time of newly laid asphalt overlay before it can be opened to traffic during the nighttime airfield pavement construction. The reduced cooling time of WMA would allow shorter airport closure time window and/or extend the time for the contractor for paving, and thus shorten the overall construction period due to more volume done each night. This is a beneficial practical advantage to hectic airports where the typical off-peak period is as short as 6–8 h. In this research, two different WMA technologies, Sasobit® and Rediset® (organic and chemical) were investigated through laboratory tests to see if there were notable differences in WMA rutting performance that could have considerable practical effects on the permissible temperature at the opening to traffic as compared to the HMA. Furthermore, a validated finite element (FE) solution for one-dimensional transient heat-transfer model is used to simulate the effect of the use of warm mix on shortening the cooling time and the overall project time. The laboratory test shows that the WMA with Sasobit has a significantly better rutting performance at the elevated temperature, enabling the WMA to be opened to traffic at a higher temperature, compared to HMA. The cooling analysis showed that, in comparison to HMA, the use of WMA could shorten the closure time of airport during the night time construction by 8–67 min (5–73% reductions), depending on the asphalt overlay thickness, specified traffic opening temperature and WMA production temperature. The use of WMA could also reduce the overall construction period by 2–16 nights for a single lift overlay, for the cases studied – which would represent a shortening of the overlay period by 4–24%.