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Just found out a 4000psi mix only uses about 6 bags of cement per yard, not the 8 or 9 I'd been guessing for years
Ran across it in an old ACI manual a guy left on a jobsite in Phoenix and it made me wonder how many other numbers I've been pulling out of thin air on my bids.
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lopez.quinn16d agoTop Commenter
Read that same thing in an old handbook from the 80s. Scary how much guessing goes into bids.
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noahmartin16d ago
That 4000psi mix with 6 bags is a solid rule of thumb but I learned the hard way that water content screws everything up. I had a bid go sideways last summer because I guessed at the slump and ended up overwatering on site to make it workable. Ended up with a weaker slab than I promised, ate $1200 in core tests. Always check the actual aggregate gradation too, that old manual might be using stuff you can't even get in your region.
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