Maturity and strength: maturity methods can speed up concrete construction and increase safety

Concrete Construction, Jan, 2004 by William Palmer, D., Jr.

To make sure that the concrete you're getting on the job is the same as the concrete used to develop the maturity relationship, verification cylinders should be made from every few truckloads. Make four cylinders, embed a maturity meter in one, then test the others at some known maturity. If the strength is within 10% of that predicted by the maturity-strength correlation cu rye, then everything is OK--otherwise, an investigation should be conducted to find out what's changed in the mix.

Cost, of course, is a factor. The intelliRock system has a starter kit for $1500 with 25 data loggers--you will eventually need more sensors (at $25 each) since they remain in the concrete, but a single reader can be used indefinitely. Con-Cure's starter package with two meters and 10 sensors also costs $1500, and though you'll seldom need to buy more sensors, if you need more meters for other locations, it will cost more. Another cost that should be taken into account is becoming properly trained to use the meters and interpret the results. Most manufacturers will provide this service for a minimal fee. The bottom line on cost, though, is that the maturity system has the potential to pay for itself very quickly, especially in the wintertime or if there are any time pressures on a job. "On cold-weather projects," says Frank Kozeliski of New Mexico-based Gallup Sand & Gravel, "you've got the cost of propane plus a guy to keep an eye on things. That adds up in a hurry."

"We're seeing a lot of use of maturity meters on pavement and also post-tensioned jobs," says Tommy Ruttura, Ruttura & Sons, Farmingdale, N.Y. "We love them, because we can immediately see when we can pull the tendons. Maturity meters--that's the best deal going right now."

For more information on the manufacturers mentioned in this article, contact them directly, or circle the appropriate number on the Reader Service Card.

Con-Cure, www.con-cure.com, 866-386-4800, or circle 1

International Road Dynamics, www.irdinc.com, 303-355-5998, or circle 2

Nomadics, www.intellirock.com, 405-372-9535, or circle 3

Onset, www.onsetcomp.com, 508-759-9500, or circle 4