IRF: What is known today about the durability characteristics of hot mix asphalt?
Dr. Waleed Zeiada: The Durability of Hot Mix Asphalt (HMA) is one key factor besides other several factors affecting asphalt pavement durability. The durability of HMA is defined as the ability of compacted asphalt concrete to maintain its structural integrity throughout its expected service life when exposed to the damaging effects of the environment, aging, and traffic loading. Raveling, stripping, and surface initiated cracking are the primary distresses associated with HMA durability issues. The durability of asphalt concrete mixtures is mainly affected by the properties of the aggregates and binder used in the mixture as well as the gradation and volumetric properties of the mixture. Based on current experience, a number of changes to mixture design have recommended improving asphalt mixture durabilities such as increasing the effective binder content, using fine gradation mixture, adopting modified binders and mixtures, and selecting the softer grade of binders or warm mix for mixtures with recycled binders. In addition, the concept of balanced mixture design by using performance tests to balance the resistance to both rutting and load-associated cracking seems promising.
IRF: What are some of the most promising innovations to extend the design life of asphalt pavement?
Dr. Zeiada: This is a very broad question and my answer to this question will touch upon only a few promising innovations in some key areas such as materials, structural design, and construction. One of the eye-catching technologies that can remarkably help in enhancing the mechanical properties of HMA and increasing the service life of pavement is nanomaterials and their applications. Perpetual pavement concept is another promising technique in which HMA pavement designed in a way to minimize critical responses to loads. Perpetual pavements are designed to last over 50 years without requiring major structural rehabilitation and needing only periodic surface renewal, which is advantageous in terms of minimizing life-cycle cost and user delays. Compaction is one of the most important processes in roadway construction in order to attain high quality and uniformity of pavement materials, which in turn better ensure long-lasting performance. Research has shown that durability is a function of pavement density. Therefore, a major positive impact on pavement performance can be realized when density is increased. Intelligent compaction is an emerging technology that can be implemented to achieve consistent and proper compaction of pavement layers.
IRF: As a researcher, what are the main advantages of presenting your work at an IRF Congress?
Dr. Zeiada: As an IRF fellow (class of 2011), presenting my research work at this great event aligned very well with the IRF mission and vision I am aware of to assist countries in progressing towards better, safer and smarter road by helping to increase road and transport investments through engagement with governments, businesses, and academia around the world. Being a faculty member at the University of Sharjah, this Congress provides me in specific with a unique opportunity to disseminate my research to governmental agencies of the UAE and local industrial organizations. After all, we all benefit from shared knowledge which helps in finding out more cost-effective and sustainable solutions to current transportation problems.