Warm Mix Asphalt

[muuddfun]

How many of you have used warm mix asphalt before, and if so what are your thoughts on its usefullness and what needs to be looked out for?

 

[emmgjld]

I am assuming you are referring to AC mixes with additives, either similar to synthetic zeolite, small wax pellits or water injection. I have not seen this though, I am told that Colorado DOT used this on I-70, near the Eisenhower Tunnel. The purpose is to improve the mix rheology and allow HMA to be placed at lower temperatures (reportedly up 100 F lower though 60-70 F is more common).

According to some discussions I have been in the middle of, problem areas would be:
Improper mixing and inadequate compaction

I would be on the lookout for segregation behind the lay down equipment and making sure compaction is quickly obtained. When the mix cools sufficiently, the mix reportedly gets hard, real fast.

 

[muuddfun]

Yes that is what I am refering to. I have been asked for some recommendation on possibly using the stuff by one of our clients. I would like to know as much as possible about it, I understand it was developed in Europe. Maybe some of our European readers have some familiarity with it?

 

[tak911]

There are a ton of different technologies being offered in the US right now, and even more in Europe. From what I've heard, some having more success than other. Each have their own unique quirks about them.

We've used it and have had some success and some issue with it thus far. There are several factors to consider. Plant calibration, RAP usage, cost (reduced energy yes, but new costs more always)....watch paver speed. Think that caused one of our problems last year.