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Paving the way to a better future

4 April 2011 No Comment

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Hi – I’m John Casola, a new face to the blog, but I guess pretty familiar to a number of people in the asphalt industry in the US. A Products Sales Manager by title, in the area of rheology, I have a keen interest and intense focus on all things asphalt.

This post is part of a series designed to give you a flavor of Malvern’s activities across the globe and I’m going to talk you through some of my recent work. I hope you’ll find it interesting and that it may even inspire you to strike up a dialogue. Feedback from people within the industry drives what I do and I anticipate that the blog will be a really useful channel for continuing that conversation.

A great AMAP conference

The timing of this blog is not accidental – we have plenty to talk about. First up I’d like to discuss the 12th annual conference of AMAP – the Association of Modified Asphalt Producers which took place in the middle of February in Kansas City.

This is an important event for me because I prepare the stats for an annual survey we present about modified asphalt use in the US. Traditionally asphalt, a by-product of crude oil processing, was used unmodified in road and pavement construction. Following on from the Strategic Highway Research Program (SHRP) of the late 80’s/early 90’s that produced the Superpave specifications, we now have polymer-modified asphalts, new grades of material that give, for example, better durability and wear. Members of AMAP clearly have a keen interest in the extent to which these newer, engineered asphalts are penetrating the market.

Some interesting highlights from this year’s AMAP State DOT survey included a greater percentage of modified binder usage.  While overall asphalt binder volume for paving was down in 2010 from 2009, the percentage of modified use was up. In 2009 the forecast for percent of modified asphalt was expected to be 27% in 2010. The actual reported total for modified binder in 2010 exceeded this forecast and hit an all time high at 32% of the total binder used. This is a very positive piece of information.  It underlines the value provided by a well engineered asphalt binder preserver in these challenging economic times when every paving dollar is in short supply.

Shaping future standards

Our increasing use of modified asphalt has highlighted a problem with traditional test methods for determining mix and compaction temperatures. These tests are about determining the temperatures at which an asphalt flows well enough to uniformly coat the aggregate. Traditional methods produce excessively high temperatures for many modified asphalts that are clearly not practical, but with little alternative the industry has been left with a trial and error approach.

Until now! For the past couple of years or so I have been working with researchers at the National Cooperative Highway Research Program on research project led by Randy C. West at the National Centre for Asphalt Technology (NCAT, Auburn University, Alabama, US  http://www.ncat.us/. The result is a new simplified technique for measuring mixing and compaction temperatures for all asphalt binders.

There is a webinar about the new method on the website http://www.malvern.com/malvern/ondemand.nsf/id/SREL-7UDHY3. It’s also written up in Transportation Research Board (TRB)  http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_648.pdf If you have any questions or would like to discuss this work in detail, just contact me at  john.casola@malvern.com.

Tell us what you think we’re eager for people to use the procedure and tell us what they think because this will refine and improve it. As things stand at the moment the draft is with American Association of State Highway and Transportation Officials (AASHTO) and American Society for Testing And Materials (ASTM) for review but not yet set in stone. So you have a chance to help us iron out any flaws and develop a really great new standard for testing.