Making our concrete structures more durable is (or should be) a national imperative for our industry. We simply cannot continue to install concrete that degrades much sooner than promised. The public, and maybe more importantly, the owners of these structures will look for different materials if they don’t have confidence in concrete.
And one of the two most common ways concrete structures degrade is from freeze-thaw damage, which can mostly be controlled with something so simpler it almost seems ludicrous: air bubbles. When I told my brother that, he thought I was joking.
But getting the right amount, and more importantly, the right kind of air bubbles is not always that easy and is virtually impossible to test for in the field. Getting 6% air is fine, but if that comes from 10 big bubbles, it’s not going to be protecting the concrete. The bubbles have to be small and they have to be distributed throughout the concrete so that there’s always one within 0.008 inches (the spacing factor). A traditional pressure meter to measure air content reveals only the total percentage of air in the mix by volume. It tells us nothing about the size or spacing of the bubbles.
But now along comes the Super Air Meter (SAM), created by one of the most creative young minds in our business, Tyler Ley, a civil engineering professor at Oklahoma State University. The SAM, through some magic that involves dissolving the small bubbles into the concrete under pressure, indicates the size and spacing of the bubbles in the field within a few minutes. Professor Ley is now marketing this device and 32 state DOTs have begun using it with promising results.
In a future story, we will get into more of the details about how this actually works, but the data suggests that it does work and will produce freeze-thaw resistant concrete. For the sake of ready-mix producers, I hope this doesn’t result in a lot more rejected loads, but I guess it falls into the category of you can’t improve something if you can’t measure it. That’s what happened with floor flatness and F-numbers.
I’ve written before about Tyler Ley and his ideas and inventions. Within the past few years, he has come up with the Tarantula Curve to describe aggregate gradation and a newspaper slurry as a curing blanket. And, he tells me, “Stay tuned as we have some more big things coming up.” I can’t wait!