aci-318

huangyhg

aci-318
i'm looking through aci-318 trying to find out where (if anywhere) it calls out for a minimum required thickness of grout on top of a pedestal, in this case i have an octagon footing supporting a piece of equipment.  i'm used to seeing 1" to 1 1/2" grout thickness on regular footings but can't seem to find where this thickness comes from.
any input on this would be appreciated...

grout is a means for constructibility of large base plates bearing on concrete that may not be flat and level. the requirement for a specific thickness is a function of flow dimension, (from either one-sided or multiple grout entrances). check with the grout manufacturer for recommendations of minimum thickness and need for relief holes in the base plate.
you may want to check out committee 351 - grouting for support of equipment and machinery. the answer depends on size of pad to be grouted, type of grout to be used, and tolerance required.
thanks for the quick responses guys, much appreciated!!
i haven't looked in aci, so i may be off on this.  i believe a minimum grout depth is for constructability.  for example, no one would be able to fill a 3/8" deep void under a 16" x 16" elevated base plate with grout.  it would be too hard to fill the void.  that's why we use 1 1/2" or 1".  i've seen contractors use 3/4", but when i'm specifying, i usually just show 1 1/2".
it also has to be thick enough to contain the leveling nuts and have room for tools with some tolerance.
according to the five star product information catalog, "for placement thicknesses of less than one inch or greater than three inches, call the products emgineering and technical information center.