cylinder test sample lids
cylinder test sample lids
(OP)
How much PSI would you lose on a test cylinder if you had no lids.
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting GuidelinesJobs |
cylinder test sample lids
|
RE: cylinder test sample lids
To paraphrase Ron from an earlier thread: The purpose of taking cylinder specimens under standardized procedures, curing them under standardized procedures, and testing them under standardized procedures is to see what the MIX DESIGN is capable of doing. The cylinders represent the mix design.
RE: cylinder test sample lids
RE: cylinder test sample lids
RE: cylinder test sample lids
NOTE 5—Asatisfactory moisture environment can be created during the initial curing of the specimens by one or more of the following procedures: (1) immediately immerse molded specimens with plastic lids in water saturated with calcium hydroxide, (2) store in properly constructed
wooden boxes or structures, (3) place in damp sand pits, (4) cover with removable plastic lids, (5) place inside plastic bags, or (6) cover with plastic sheets or nonabsorbent plates if provisions are made to avoid
drying and damp burlap is used inside the enclosure, but the burlap is prevented from contacting the concrete surfaces.
RE: cylinder test sample lids
11. Transportation of Specimens to Laboratory
11.1 .....Prevent moisture loss during transportation by wrapping the specimens in plastic, wet burlap, by surrounding them with wet sand, or tight fitting plastic caps on plastic molds......
Since I'm hauling wet sand or wet burlap I think the lids are the way to go.
RE: cylinder test sample lids
I have no question about the standard. Just trying to figure off the record, how much 24 hour non curing would matter.
RE: cylinder test sample lids
Similarly if the mix design which the cylinders represent is for 6000psi or greater and if during the initial curing period the ambient air temp was maintained between 68F and 78F with a relative humidity around 100% I'd say the strength loss due to not having lids is near zero.
If, however, the contractor failed to provide an environment for Initial Curing meeting the requirements of ASTM C-31 and as a result the strength test specimens were subject to non-standardized Initial Curing conditions and the lab manager failed to provide the tech with lids....well then your guess is as good as the next guy's.
(Notice how I gave the tech the benefit of the doubt on the lid thing?)
By not accurately following the accepted testing procedures you just open the door and invite in these kinds of criticisms. Didn't your dad teach you not to run to the hardware store and buy the rope for your own hanging?
RE: cylinder test sample lids
RE: cylinder test sample lids
Like lack of will/foresight to properly train/motivate competent techs perhaps.
RE: cylinder test sample lids
RE: cylinder test sample lids
That's because contractors insist on mixes with enough cement to overcome the lower strengths associated with not performing initial curing because they DO NOT want to pay to perform correct initial curing.
A credible argument could be made that not performing initial curing increased the worldwide shortage of quality cement powder.
RE: cylinder test sample lids
You are correct, though, that additional cement is used in most mixes. It is more of a point that since there is no "history" of concrete manufacturing in remote areas using specific aggregates and cement types, then you have a target strength at the mix design level that is in the order of 8 to 10 MPa higher than the required 28-day strength (if the standard deviation of a mix isn't known, you have to up considerably the target strength). Of course, as a "history" does develop (say after 30 or 40 test results), they could reduce the cement content. But, it is seldom done not the least bit of which is likely due to overseeing authorities not wanting to accept a reduction of the original mix design consituents - or the contractor note wanting to be bothered to save a bag of cement per m3.
RE: cylinder test sample lids