failing concrete cylinders
failing concrete cylinders
(OP)
I've got a large concrete parking lot pour. The concrete is supposed to be 4,000psi with fiber reinforcement and general specs in accordance with ACI 330.1-03. One slump test and one set of cylinders were taken for each 50yds. Cylinders had a 7 day ave of 2,160psi and 28 day ave of 3,355psi. the concrete supplier took their own QA samples and I'm trying to see their results for comparison. the subgrade compaction was confirmed within acceptable density and moisture limits. What is the acceptable mitigation? removal and replace? Wait for signs of failure then replace? combination?





RE: failing concrete cylinders
If fly ash or similar materials were used, the strength gain would be later than 28 days.
The slump test is really just an indicator of the free water in the mix at the time. One set of cylinders seems a little light when it comes to cylinder making by one technician, curing and handling and no room for future verification to hang your hat on.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: failing concrete cylinders
RE: failing concrete cylinders
84% of design strength is quite low and that is the AVERAGE. If it was a set or even two at that range I'd be less concerned, but that is a significant reduction in strength and will likely affect the long-term performance of the mix.
RE: failing concrete cylinders
RE: failing concrete cylinders
RE: failing concrete cylinders
If you have cash, you can just pay anyone you want to fix the problem.
RE: failing concrete cylinders