Effect of Long Term Oven Aging on Dynamic Modulus of Hot Mix Asphalt

摘要

The AASHTO R30 standard practice for hot mix asphalt (HMA) anticipates that long-term oven (LTO) aging of HMA simulates 5-7 years of in-service of pavement under actual field conditions. However, actual aging time in the field might depends upon several other factors such as volumetric properties of mix, mix type, mean annual air temperature (MAAT), and depths of pavement. The present study was undertaken to determine the time of field aging simulated by LTO aging of a selected HMA mix, using dynamic modulus as an indicator of performance. Dynamic modulus testing was conducted on unaged and LTO-aged specimens at different temperature and frequency combinations. It was observed that aging increases dynamic modulus, ranging from 50 - 80percent. The Global Aging System (GAS) model was used to predict aged dynamic modulus for different times and depths of a pavement (6.25 mm, 12.5 mm, and 25 mm). Predicted aged moduli were correlated with laboratory measured LTO-aged dynamic modulus. It was found that with 6percent air voids, top 6.25 mm thickness of pavement aged within 14 months of service life, while it would take about 2 years and 6 years to achieve similar aging at a depth 12.5 mm, and 25 mm, respectively.