摘要：

KUSAM, ABHILASH. Laboratory Evaluation of Workability and Moisture Susceptibility of Warm Mix Asphalt Technologies with Reclaimed Asphalt Pavement Material. (Under the direction of Dr. Akhtarhusein A. Tayebali). In this current world there is a need to use cleaner and more sustainable technologies. One such technology which might soon replace the conventional Hot Mix Asphalt technology is Warm Mix Asphalt Technology (WMA), which helps reduce production temperatures. It also helps increase workability at lower temperatures thus reducing the energy required to heat the materials. Lower production temperatures also mean less harmful emissions during the pavement construction, and also increased haul distances. Various laboratory and field studies have shown improved workability at lower temperatures when WMA technologies are used. However, use of WMA technologies has led to a major concern of moisture susceptibility because of the use of water based technologies. Use of recycled material to construct pavements is also a popular way to move towards sustainability. Reclaimed Asphalt Pavement (RAP) material has been used in the pavement industry since a very long time. By recycling construction materials, the cost involved in transporting them is also lowered. The RAP material gives extra stiffness to the mixture, which is beneficial to prevent rutting but in turn decreases the workability and long term durability. It is believed that the use of WMA technologies can eliminate the workability problems associated with the use of RAP material. Since WMA technologies improve the workability of the mixtures, there is a possibility that higher amounts of RAP can be used when WMA technologies are used. With so many new technologies out in the field, it is very important to find out the compatibility of WMA technologies in preparing high RAP content. For this there is a need to study the workability and moisture susceptibility of WMA – RAP mixtures. This research study focuses on using two WMA technologies – Evotherm 3G and The PTI Foamer with three different RAP percentages – 0%, 20% and 40%. NCDOT 9.5 B mixtures were prepared with a combination of these WMA technologies and RAP contents. These mixtures were evaluated for workability and moisture susceptibility, and compared to the workability and moisture susceptibility of the corresponding HMA mixtures. Tensile Strength Retention Ratio test was done to evaluate the moisture susceptibility, while the workability was evaluated by %Gmm evolution curves. The effectiveness of Evotherm as an anti-strip additive was evaluated by a litmus paper test using StripScan. TSR ratio was observed to decrease with increase in RAP content for HMA as well as the two WMA technologies. Foamer mixtures showed better workability than Evotherm and HMA mixtures. The workability decreased with increase in RAP content for all three types of mixtures. The volatility of Evotherm additive was measured using the litmus paper test. The results were observed to be similar to that of LOF 6500 and Morelife 2200 anti-strip additives from a previous study conducted at North Carolina State University. Evotherm can work as an anti-strip additive for 0% RAP mixtures since the TSR ratio was above the minimum limit required by NCDOT. Copyright 2014 Abhilash Kusam All Rights Reserved Laboratory Evaluation of Workability and Moisture Susceptibility of Warm Mix Asphalt Technologies with Reclaimed Asphalt Pavement Material

展开