Low strength cores 1

[LJ_]

Hello!

We have taken some cores out of a structure and the individual cores go as 84.5%, 84%, 83%. None of them go below 75% but the average is less than 85%. Should I take more cores ?

Or should the structure be demolished?

 

[Enable]

LOL what a stark contrast: more cores or demo the structure! I think there might be some more options to consider

First, the grouping is pretty consistent and close to 85% so prior to full demo, yes, take more cores. Second, the 85% requirement can be put aside if there is a rational engineering reason to do so. In this case, with your field samples within a very close range and an upper 95% CI extending to 85.7 mPa (t-distributed, n=3 -> 2 degrees of freemdom)...you have every reason to believe this might pass.

If that doesn't hold weight with you. Fine, still consider that prior to demoing the building, you can specify a load test and test the performance in service. That's good backing for engineering judgement. I mean...gotta be cheaper then demoing and reconstructing a building!

EDIT - for those curious the field core 85% requirement comes from (at least in Canada) CSA A23.1/2 4.4.6.6.2.2

EDITx2 - Just occurred to me that the OP is probably joking...damn I was hoodwinked. Well played sir.