Cocrete Testing
Cocrete Testing
(OP)
One of Testing lab test concrete cylinders 1 at 7, 1 at 28, and 1 at 56, The cylinder tested at 28 days achieved strength less than specified. Lab hold third cylinder for 56 days, 56 days test result passed as per ASTM and CSA international minimum 2 cylinders required to be tested at 28 days. Is there any way I can justify above test results as per ASTM, CSA or ACI?
Thanks to all in advance for helping me
Thanks to all in advance for helping me





RE: Cocrete Testing
The original testing should have been 1 test at 7 days and 2 at 28 days (assuming 6"x12" cyls). ACI requires an average of 2 specimens at 28 days for the record strength. If you want to do testing at 56 days (which you don't know on the front end), there should have been two extra cylinders on hold. In lieu of testing cylinders at 56 days, coring is acceptable. Follow the procedures in Chap. 20 of ACI.
What were the actual strength results and percentages of design strength at 7 and 28 days? It's possible you didn't actually have a problem...just a poor interpretation of results. Did the mix design have slag cement or fly ash in it?
RE: Cocrete Testing
RE: Cocrete Testing
RE: Cocrete Testing
Thanks
RE: Cocrete Testing
Check out this thread -
thread507-252689: 28 day vs. 56 day concrete breaks
I have a post there that summarizes ACI Chapter 5 acceptance of concrete - that may or may not be the same as CSA but check it out. Basically, if you have one flawed test, you don't need to immediately go to core tests. You can evaluate the lower strength and see whether the lower f'c is acceptable in the concrete portion of the structure the flawed test represents.
If the lower f'c still works in calculations - you as the EOR can approve it but the contractor is compelled to adjust the mix to avoid lower strengths in the future.
RE: Cocrete Testing
not really, it very common to shear a corner of a cylinder in a bad test, since alot is riding on this results, you have to be 100% correct that your findings are accurate. You need to be breaking two 28, no if, or, buts.
RE: Cocrete Testing
RE: Cocrete Testing