5000psi grout as a structural footing?

[paullaup]

in the case of a strip footing for a CMU wall (the wall is actually non-structural) What are the pro's and cons of using 5000psi grout instaed of using concrete.
Is it possible to use it and reinforce it in the same manner as concrete. Are there bond issues between the bars and grout? Are there shrinkage issues?

 

[jheidt2543]

Why use the grout? Concrete is about $65-$75/CY and non-shrink grout is about $34-$50/CF (yes, CF which equals $918-$1,350/CY) So, why use grout?

 

[paullaup]

The issue of cost is irrelevant in this case. The contractors want to uise it. Maybe they have an abundant supply of it. The question was asked to find out about the technical implecations, not the economic implications.
Anyone with answers??

 

[paullaup]

The issue of cost is irrelevant in this case. The contractors want to use it. Maybe they have an abundant supply of it. The question was asked to find out about the technical implecations, not the economic implications.
Anyone with answers??

 

[smaug6]

Maybe water permeability reduction is the issue the contractor wants to address.

 

[jheidt2543]

Ok, so here are some thoughts if you use the grout (I'm assuming a premixed grout product, not a sand cement grout):

1. It should not be a metalic grout.

2. I would think you could design it the same as a reinforce concrete footing. I do seem to remember that the set time for grout is much faster and they tend to generate more heat in large sections. So, I would find out what grout is being used, get a product data sheet and contact the manufacturer's techical staff to verify what I just said.

3. To get a better yeild, some couse aggregate should be used. So, I would request a mix design and test cylinders.

4. I've never seen grout used as a footing this way because of COST.

 

[Ingenuity]

paullaup,

When you say "grout" it may take on several meanings. Clarify with the contractor on exactly what he/she defines as grout.

Water and cement is also a grout - but I would not use it for a footing application, even though at w/c=0.40 I will probably get 6,000 + psi at 28 days on 2" cubes!

Does it have course aggregate of max size of 3/8", or only fine (sand) aggregates?

A sanded grout will potentially suffer from excessive shrinkage for a strip footing element which I imagine is 12" wide min and a depth of 8+ inches, and somewhat lengthy.

Get a copy of the contractor's proposed grout mix design before you comment/commit.

Since you state that this wall is non-structural you are probably not that concerned with with bond related issue anyway, and I am not sure if it will be a factor anyway as reinforced CMU walls and bond beams/lintels are grouted and bond is not specifically addressed in these situations.

Ask if it going to be site mixed or ready mized, to ensure some quality - If you accept the alternative make it a "performance" criteria where the emphasis is on the contractor to achieve the same/equal to a concrete footing.


HTH

 

[dicksewerrat]

Require third party testing of this"grout". Cylinders and beams.

 

[jheidt2543]

Contact L&M Construction Chemicals, Inc. at

http://www.lmcc.com.

They manufacture a variety of grout materials and their techical services department may well be able to answer your questions in more detail.