control joints spacing resource

[hippo11]

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.

 

[UcfSE]

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.

 

[SperlingPE]

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

 

[twinnell]

ACI 360 is now 06. They have updated a lot. 18 feet spacing max. 1.5 to 1 ratio max