Influence of void in mix on rutting performance hot mix asphalt pavement with crumb rubber additive

Pavement construction is expected to support vehicle loads and be weather-and waterresistant. In tropical regions with high temperatures and high rainfall intensity, pavement design and construction must consider the effects of temperature. The addition of crumb rubber (CR) can improve the performance of asphalt concrete in response to vehicle loads and ambient temperature. Fiber-shaped CR can be mixed with the aggregate and bitumen in asphalt concrete. In this study, CR was added to the aggregate in a type of asphalt concrete for wearing courses known as hot mix asphalt (HMA). A series of tests were conducted using the Marshall standard or immersion and wheel tracking machine (WTM). CR was added to the HMA at 5%, 10%, 15%, and 20% in aggregate and further mixed with bitumen with 60/70 penetration grade. The additive materials increased the value of the Marshall stability compared to the virgin asphalt mixture. However, this result was not obtained in the WTM test; the addition of CR increased rutting compared to the asphalt mixture without additive. The addition of CR to HMA reduced the voids in the mix, and weakened the capacity of the asphalt concrete to support repeated vehicle wheel loading.