CMU pilaster grouting 1

[Kris the Engineer]

Hello all,
I have a general question regarding large CMU pilasters that are 32" sq and larger. a 32" sq pilaster with 8" block on the exterior, leaves a 16" sq hole opening in the middle of the pilaster. These pilasters are generally used as cantilever elements used to support fences or gates.

My question is if the center of the pilaster has to be grouted solid or can it remain ungrouted as long as the correct ties and reinforcement is used?

Thanks.

 

[phamENG]

Depends on structural demand and environment.

Was it analyzed as a hollow column/pilaster, or a solid column? Is there anything in the environment that could cause problems with a hollow column/pilaster? Can water get in and degrade it from inside? Carry contaminants in there? Is having it hollow a thermal concern for the structure?

 

[MotorCity]

I think it also depends on how the gate/fence is attached to the pilaster. If its only attached to the block on one face of the pilaster, the whole connection could just pull out. I am not sure how you would engage the entire hollow "tube" section of the pilaster by just attaching to one face of it. Grouting it solid would certainly engage the entire pilaster section

 

[JLNJ]

The load=carrying capacity is very likely more than plenty. Instead, I'd worry about freezing and thawing of water which (inevitably) finds its way into that inside section.

 

[masonrygeek]

Based on the comments above, make sure that the mason is qualified to grout and reinforce a masonry wall. There are quite a few things to make sure are done properly including getting the right slump, vibrating and reconsolidating the grout, etc. Check out the Grouting and Reinforcement Training spec language that can be used to qualify a contractor:

https://www.imiweb.org/spec-language-2/#get-spec-language.