Concrete vs Grout in a Retaining Wall
Concrete vs Grout in a Retaining Wall
(OP)
The contractor asked me if he could use an equivalent strength "grout" instead of "concrete" for a concrete retaining wall I designed. What he is asking is if I will approve the use 3/8" aggregate instead of 3/4" aggregate. He wants to pour using a 2"Ø hose with a grout pump instead of using a 4"Ø hose with a rock pump or a boom pump. I called the local concrete suppliers and the only downside they mentioned when using smaller aggregate is that there tends to be more shrinkage of the material. I would like to know what others think about this and what additional downsides there may be. Thanks.






RE: Concrete vs Grout in a Retaining Wall
RE: Concrete vs Grout in a Retaining Wall
With the smaller aggregate you would possibly get some additional vertical cracks down the wall closer than the 25 ft. The response to the 3/8" mix for me would be to use closer control joint spacing and perhaps up my horizontal temperature/shrinkage steel in the wall.
It's a trade off.
RE: Concrete vs Grout in a Retaining Wall
Richard A. Cornelius, P.E.
WWW.amlinereast.com
RE: Concrete vs Grout in a Retaining Wall
Also, I'd make sure he's not going to backcharge the project for the difference--with the additional paste, I would think the smaller aggregate mix would be more expensive.
RE: Concrete vs Grout in a Retaining Wall
Stay with the 3/4" aggregate...lots more cracking otherwise.
RE: Concrete vs Grout in a Retaining Wall
Also, when you specify 3/8", you are getting materials that passes a 3/8" sieve, so only a few percent is actually 3/8, with the remainder being smaller. The same goes for other sizes, so it is not like you have a pile of each exact size of rock and they get mixed, unless you specify a very expensive gap-graded mix.
RE: Concrete vs Grout in a Retaining Wall
RE: Concrete vs Grout in a Retaining Wall
RE: Concrete vs Grout in a Retaining Wall