measurement in a cold slab

[CC Solutions]

That's exactly right Joe! You are doing the right thing. Just let the client know that the temperature of the concrete should be at service temp for the most dependable readings. You could extrapolate a little (the ASTM has some flexibility) and you know which way to extrapolate whether the concrete will be warmer or cooler during service.

I have seen guys take readings on 80 degree slabs that are low, then when the slab cools to 67 they are high. If your readings are coming in close to the cut-off point you will want to get that slab at service temp.