We talk with leading educators in the field of asphalt technology in an effort to tune in to academia on important industry issues.
Chris Williams is the Gerald and Audrey Olson Professor in Civil Engineering at Iowa State University’s Department of Civil, Construction and Environmental Engineering and a Materials Engineer at the Center for Transportation Research and Education (InTrans).
What drew you to engineering, and in particular, transportation?
I went to college not knowing really what I wanted to study. I knew I was really good in mathematics so I thought that I would focus on either economics or engineering. I decided on engineering. At the University of Vermont at the time, they had three core engineering disciplines in civil, mechanical and electrical engineering. The idea that I could be an engineer and have the opportunity to work outdoors became really appealing to me. I had a professor in civil engineering that liked challenging me and he encouraged me to take elective classes in transportation. Professor Oppenlander then encouraged me to go to Purdue for my graduate studies. One summer, I worked for the Vermont Agency of Transportation as an inspector on a bridge expansion project on I-89 over the Winooski River and had the opportunity to do inspection work with some asphalt paving.
How can adding rejuvenators positively affect asphalt mixtures with high RAP?
Rejuvenator is a tricky word and I am not sure we have arrived at a common definition in the industry. Some would say a material that is added to asphalt and makes it softer is a rejuvenator but we really need to look further into the mechanism that makes the asphalt softer. Some materials are used to soften asphalt but do not chemically react with the components of the asphalt whereas others do chemically react with various constituents of an asphalt. My thoughts are we look at the hardened asphalt that is in the RAP and we know that there is a molecular weight distribution and that from the start of a new asphalt pavement the distribution changes over time. So we can use a combination of chemistry in altering the molecular weight distribution through both chemical reactions and the use of softening agents that install the lower molecular weight materials back into the molecular weight distribution.
What are you learning about chip seal best practices through your research?
Ashley Buss, Doug Gransberg and I are working on chip seal research together. Doug brings the New Zealand experience to the table, Ashley is focused on the emulsions and hot seals and I look at how we can bring the asphalt binder and aggregate characteristics together. What we are learning is simply reinforcement of what we already know that having a quality source of materials is what makes a quality chip seal and that chip seals work well when used for the appropriate applications.
Do you see growth potential for biopolymer use in asphalt production?
We really do see a great opportunity to use the biopolymers in asphalt pavements. Our lab testing is showing that the biopolymers are not only performance advantaged, but they are also cost advantaged. Argo Genesis Chemical, a sister company of Seneca Petroleum, licensed the biopolymer technologies and recently had a firm design and build a pilot plant capable of producing one ton per day of biopolymers to scale up the technologies. We are working on evolving the biopolymer technology so that it is turnkey in existing polymer production facilities. We are looking at producing biopolymers in our pilot plant later this year and hope to use them in trial paving projects.
Where should today’s engineering students focus their research in the asphalt field?
This is a really good question! I think the undergraduate engineering education we deliver today is very good but in many cases it is not broad enough. If today’s students want to be tomorrow’s change agents, they need to have a broader understanding of materials in other fields such as through chemistry and chemical engineering facilities. I also firmly believe students need to have a better understanding of business operations, cash flow and the value chain of materials as they proceed through a production facility. One of the other challenges a lot of engineers face is effective communication – being able to break down a complex engineering problem and explaining it to non-engineers. Working continuously on improving their writing and public speaking skills is paramount to continued success.
