| Author |
Message |
Dewayne Dean
Senior Member
Username: ddean
Post Number: 132
Registered: 02-2016
| | Posted on Thursday, June 08, 2017 - 01:49 pm: |    |
I am wondering if any of you have a standard for what is acceptable cracking in concrete slabs?
I know that it all starts with a good mix design.
No matter how good the design is, the concrete contractor can mess it up.
Is there a way of quantifying the cracks and saying if the cracks exceed [____] , then…. |
Nathan Woods, CSI, CCCA, LEED AP
Senior Member
Username: nwoods
Post Number: 713
Registered: 08-2005
| | Posted on Thursday, June 08, 2017 - 02:43 pm: | |
"Theres a crack in every bag of cement"
--- my favorite and colorful old timer superintendent
Cracks fall into two categories, structural, or aesthetic. There are ACI documents that address curing shrinkage, curling, saw cutting, floor flatness, etc... that are primarily about the structural slab detailing to control cracking and having the placement of shrinkage cracking following the control joints (which is a study unto itself), but none of those define what an acceptable crack is.
Architecturally, assuming the cracking is related to curing of concrete and not building movement (ie, a dynamic, ongoing problem), then you can repair or isolate the cracks to prevent them from transmitting through the flooring materials. But if its exposed concrete....I think it's just a judgement call based on looks. I am unaware of any reference standard.
I take great care in the placement and timing of my sawcut joints, and specify SoffCutting within 12 hours of placement, and I am very specific about the placement of vapor barriers, curing methods, mix design (W/C ratio), and so forth. The only thing I can't control is the weather, which does have a huge roll in the curing of concrete and resultant shrinkage rates and potential cracking. |
anon (Unregistered Guest)
Unregistered guest
| | Posted on Thursday, June 08, 2017 - 04:31 pm: | |
You could do this and get no cracking:
http://www.concreteconstruction.net/how-to/materials/use-reinforcing-to-stop-cracking_o |
Michael Chusid, RA FCSI CCS
Senior Member
Username: michael_chusid
Post Number: 289
Registered: 10-2003
| | Posted on Thursday, June 08, 2017 - 06:27 pm: | |
There may be standard ways to measure the width and spacing of cracks, but acceptability is up to your evaluation of the application. I believe the CMU industry has a standard for measuring cracks.
There are many types of cracks that are not necessarily classifiable as structural or aesthetic. My favorite is Alkali-Silica Reaction (ASR) Cracking in which a concrete structure turns itself into concrete crumbs.
The type of shrinkage compensating concrete provides a way of prestressing concrete; the concrete expands and puts the reinforcing into tension that puts puts the concrete into compression. In addition to the shrinkage compenstion, precast prestressed concrete and post tension concrete accomplish the same thing.
I have published papers on both topics. Let me know if you want citations.
Michael Chusid, RA FCSI CCS
www.chusid.com www.buildingproduct.guru 818-219-4937 |
Dewayne Dean
Senior Member
Username: ddean
Post Number: 133
Registered: 02-2016
| | Posted on Friday, June 09, 2017 - 03:42 pm: | |
Thanks Guys |
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