Maturity Testing 1

[windies]

Can anybody suggest a good economical system for testing Maturity of Concrete. In particulair our client wishes to obtain high early strength concrete. (Approx 3200psi in 24 hours) that will allow early stripping of forms.

 

[Ron]

There really isn't a shortcut to actual maturity testing. If you follow ASTM, you'll need to develop a maturity curve using a maturity meter with results of strength or maturity vs. time.

If you have a lot of concrete to test this way, develop a curve for the mix design and use this as you QA method.

If you are only looking at form stripping, use Lok-Test or similar methods to gauge early strength.

 

[RiBeneke]

Ron,
I have not encountered Lok-Test. Is it something like a Schmidt hammer test ? Can you explain please.

 

[Ron]

Rich...it's a pull-out test. The semi-conical device is cast into the concrete at placement, then a shear-cone "plug" is pulled out of the concrete using a special calibrated jack. Can be correlated to cylinder strengths to give relatively accurate form/shoring removal data.

 

[RiBeneke]

Thanks Ron. I have not seen it in our country. Sounds an effective simple test.

 

[Ron]

Rich,
Yeah, it is rather simple. It was popular in Canada in the 80's, but not so much in the US. I had a Canadian partner at that time and that's how I became familiar with it. The pullout jack manufacturer didn't promote the test method as well as they could have, even though it is has an ASTM method and I think would save lots of effort. It's also cheaper than maturity testing!
Ron

 

[JohnGn]

Maturity testing, done properly, is an excellent method of determining the in-place strength.

My company has done thousands of maturity tests, and we even developed our own system to meet our stringent demands.

We typically find that the in-place strength is so much higher than the strength of a representative test sample at the same age that it makes great economic sense to do maturity testing.

Maturity and Lok-testing are similar in that one needs to establish a baseline for the test. Once that baseline is created, our test costs nothing for equipment and only 10-15 minutes of time.

I will mark this thread if you wish more details.

John
Con-Cure Corp.
St. Louis, MO