Durability test waiting period

[structural87]

Good day,

How much time is needed to do the concrete durability tests ? The contractor is telling me 120 days are needed before we can do it. A laboratory guy once told me 28 days is enough.
specs doesnt say much about this subject.

Thank you

 

[Ron]

What tests are you referencing? For strength, 28 days is typical. I'm not sure which durability tests you are considering. Please expand.

 

[structural87]

I am considering 3 tests for durability :
1- Water penetration
2- water absorption
3- Resistance to chloride ion penetration.
i would like to know after how much time we can conduct the tests.

 

[concretemasonry]

Is this for a freeze-thaw durability test?

Those take a long time to get the necessary cycles to reflect the absorption effects of the sample. That test requires subjection of manufactured concrete products and requires each sample (or set) to go through freezing and thawing cycles of samples and making sure they are always in a shallow layer of water.

They run the test and weigh the samples after each cycle to determine the weight loss. - It is an accelerated, cycled test. I don't have the ASTM specification, but it can be obtained from the ASTM site.

That test does take time, but concrete products producers (especially pavers) do it as a quality control measure. I have seen core samples of poured in place concrete cored and tested.

Dick



Engineer and international traveler interested in construction techniques, problems and proper design.

 

[cvg]

AASHTO T259 resistance of concrete to chloride ion penetration is 28 days
ASTM C642 and C1585 tests for water absorption do not list a time but the assumption is that the concrete cylinder is 28 days or greater
not sure what test you propose for water penetration

 

[Ron]

Agree with cvg....the intent is to test concrete that has reached its design strength, since most parameters are related to that. For most concrete, that provision is at 28 days or more.

 

[darthsoilsguy2]

sounds like the Contractor is talking about how long to finish a freeze-thaw test and You are talking about how long until you get it started....

If the contractor and concrete supplier do propose to stand behind their concrete by freeze-thaw testing, you should read the test before the samples are collected if they will be coming from the structure itself. The lab tech can invalidate any samples that fail to perform as being non-representative if they can find a placement irregularity (void from vibration cavitation void) or surface irregularities to the sample from rebar or a tendon sleeve or other embedment, and you won't hear about it until the testing is done. in other words, you would want to see the samples look good to keep from getting hustled into being 4 months down the road with inconclusive results.

 

[shazi1]

if its casted sample 28 days is generally followed for permeability, but in case of core cutting, contractor generally delays to 56 days hoping concrete to give better results.. but for core cutting from hardened concrete, I dont think durability requirement is passing criteria.