Precast Stripping Test 1

[LakeNormanTiger]

Friends,

In an effor to reduce our rework dollars for the upcoming business year we are looking at some of the more costly problems that we have with our process. One problem is stripping the product early or when it is to "green".

I have been asked to find out if there is a test that can be preformed on a product when there is a question if it will break during stripping. Bear in mind that the products that I am talking about are 4 diameter precast manhole pieces, and that making cylinders for each piece or for each batch of concrete is not a cost effective test. ie: We would spend more testing than we would lose by not doing anything.

Thanks for any help that you can give.

LNT

 

[ACtrafficengr]

Would breakage be due to stripping the forms, or concrete not strong enough to support it's own dead weight unsupported?

I'd mix up a batch of minimally-acceptable concrete, do a bunch of test cylinders, find out how long it takes to reach the desired minimum strength, and add a factor of safety.

------------------------------------------
"Come to think of it, there are already a million monkeys typing on a million typewriters, and the Usenet is NOTHING like Shakespeare.

Blair Houghton

 

[StephenA]

Some ideas.

Use a Schmidt hammer test, although not very reliable in a absolute sense it could help.

Change the mix, increase the cement content, use an additive to reduce the water, add polypropylene fibres, increase curing temperature, use High Early Strength cement. Although all cost money, it may be less that you are wasting at the moment.

StephenA

 

[dicksewerrat]

4 foot diameter manhole sections? Are you curing with steam? Wet cast or dry cast? How long have you been waiting?

 

[SlideRuleEra]

How about a little "low-tech" in-house experimentation? The biggest factors are probably "time" and "temperature". Keep notes on the environmental conditions and try stripping at different times - your company's employees are in the best position to determine what results are acceptable and what are not. After a very few well choosen trials you will probably have your answer.