huangyhg

control joints spacing resource
where can i read about good rules of thumb for spacing control joints/construction joints in a slab on grade...where, how often, etc?
thanks.
check out our whitepaper library.
the pca has a publication called "building movements and joints". in it it talks about controls joints for buildings but also has a chapter on plain sog. they provide a table for recommended joint spacing based on slump, aggregate size and slab thickness (t). the rule of thumb provided is 24t for aggregate < 3/4-inch, 30t for aggregate > than 3/4-inch, and 36t for low-slump.
for sog with reinforcement, there is the subgrade-drag-method equation describing the required area of steel to hold the cracks tight.
here are some publications that i use for reference.
after several problems with floor slabs on grade, i don't think that there is anything like a "rule of thumb" for floor slabs.
metezger/mcguire web site has some helpful information.
there is a publication "design of slabs on grade" [aci committee 360r-94].
guide for concrete floor and slab construction aci 302.1r-04
army tm 5.809.12 / air force afm 88-3 chap. 15
aci 360 is now 06. they have updated a lot. 18 feet spacing max. 1.5 to 1 ratio max

__________________
借用达朗贝尔的名言：前进吧，你会得到信心!
[url="http://www.dimcax.com"]几何尺寸与公差标准[/url]