Understanding the short-term aging of warm mix asphalt using rolling thin film oven

Abstract

Standard Rolling thin film oven (RTFO) test at 163°C for 85 minutes has been investigated and revised to represent the short-term aging of the warm mix asphalt (WMA) binder which is mixed and aged at lower temperature. Because of wide mixing temperature and variation in duration of storage and paving time, field short-term aging differs significantly. To simulate the reduced aging of WMA binders in the laboratory, series of RTFO tests were conducted on two binders at three different temperatures and for four aging periods. Short-term oven aging (STOA) of mix was performed for the same time duration at those three RTFO aging temperatures. A RTFO aging model was developed correlating the rheological properties of STOA mix. Following the aging model developed in this study aging temperature and duration can be selected for RTFO testing to simulate aging effect that a binder experiences in STOA of mix. It is observed that the change in aging index of binder follows a linear relationship with aging time, and the rate of change of the aging index changes linearly with temperature. This study also affirms that STOA of mix exhibits more sensitivity to temperature than that of RTFO aging of binder. Investigation of plant and laboratory mix depicts that very small portion of mix aging occurs during mixing phase however, main portion of short-term aging occur during the storage of plant mix or oven aging of laboratory mix. Because of wide mixing temperature RTFO aging test protocol need to be adjusted.