A new 'buzz' word in our industry is Warm Mix Asphalt (WMA). According to the National Asphalt Pavement Assocation (NAPA), WMA is the wave of the future. NAPA defines warm mix as 'the generic term for a variety of technologies that allow producers of hot-mix asphalt pavement material to lower the temperature at which the material is mixed and placed on the road.'

Such reductions have the obvious benefits of cutting fuel consumption and decreasing the production of greenhouse gases. Other benefits include better compaction on the road, the ability to haul paving mix for longer distances and the ability to pave at lower temperatures.

WMA was developed in Europe and has been heavily used there for the last 10 years. It has piqued the interest of industry associations in this country, especially NAPA and the Federal Highway Administration (FHWA). Over the last two to three years it has been growing in popularity here.

There are currently over 15 different technologies on the market to produce warm mix. Some involve an additive (wax, powder, foam) that is introduced into the asphalt mix that alters the viscosity and allows workability of the mix at lower temperatures. Other technologies involve water injection systems that inject a very small percentage of water into the mix to facilitate foaming of the asphalt, allowing aggregate to be coated with asphalt at lower temperatures.

Based on field data and laboratory studies, it is clear that warm mix is the future of our industry.

If you are interested in learning more about WMA, please visit NAPA's website dedicated to this technology at www.warmmixasphalt.com.