Is Your Lab Ready for Balanced Mix Design?

BY AsphaltPro Staff

The product gallery listings we bring you each month alternately focus on mix production and paving- and pavement maintenance-related equipment and services. This month we’re shaking things up with a deep dive into what laboratory and testing equipment manufacturers and providers have on offer. If you’ve been following along with our weekly toolbox tips emails, you know we recently showed how to perform I-FIT and IDEAL-CT tests.

These are merely two of the tests associated with the balanced mix design (BMD) concept taking hold in the United States. What else is associated with BMD implementation? In the guidance document it’s preparing for the National Cooperative Highway Research Program project 10 107, the National Center for Asphalt Technology (NCAT) has identified eight tasks for BMD implementation. Rather than step on NCAT’s copyright, I’ll point you to the Fall 2021 NCAT Newsletter for a detailed look at those eight tasks.

NCAT Director Randy West shared that one of the positives of BMD is it will overcome the shortcomings of the Superpave mix design system, which has a great deal of dependence on aggregate specific gravity. At the BMD Implementation Conference Sept. 2-3, 2021, presenters seemed unified in the message that the Superpave system solved problems of rutting seen in pavements prior to the 1990s, but did not fully address problems of cracking in pavements. BMD’s goal is to find the sweet spot, and to do so while giving contractors a bit more latitude.

“BMD tests will give us better measures of a mixture’s resistance to rutting and cracking or other critical distress and therefore will lead to better performing pavements,” West shared. “It will also enable contractors to be more innovative in how they meet the BMD criteria.”

If mix producers, designers or others in the field are concerned about new equipment additions or new testing criteria, there are resources at the NCAT website to assuage fears and walk professionals through steps for adding lab “infrastructure.” Visit https://eng.auburn.edu/research/centers/ncat/education/bmd.html

But there’s more happening in the world of quality control/quality assurance than finding the most expedient way to implement BMD-favored testing protocol. Let’s take a look at the next few pages to see what equipment manufacturers and lab service providers shared with you for this special gallery.