Lean Concrete
Lean Concrete
(OP)
Hello.
We had to over-excavate for retaining wall footings in Atlanta while chasing competent bearing soil. The contractor wants to use a lean concrete to fill the over-excavation and submitted a mix design that has a w/c ratio of 1.06 for 1000 psi.
Info I've found about lean concrete just says that it is characterized by 'high' w/c ratios. 1.06 seems well beyond 'high' to me.
What do you think?
Thanks.
We had to over-excavate for retaining wall footings in Atlanta while chasing competent bearing soil. The contractor wants to use a lean concrete to fill the over-excavation and submitted a mix design that has a w/c ratio of 1.06 for 1000 psi.
Info I've found about lean concrete just says that it is characterized by 'high' w/c ratios. 1.06 seems well beyond 'high' to me.
What do you think?
Thanks.






RE: Lean Concrete
Garth Dreger PE
AZ Phoenix area
RE: Lean Concrete
Because the mix is obviously very lean, you will likely have very little paste, so shrinkage will not be a problem (a problem with typical high W/C ratio mixes.) I'd be inclined to use slightly more cement than you mention to provide a margin of error, but there is no strong reason to demand higher strength.
RE: Lean Concrete
As TXStructural said, add cement to bring it down to that.
RE: Lean Concrete
RE: Lean Concrete
RE: Lean Concrete
Before such materials became "accepted" we simply used a weak concrete mix for the same thing.