I think you may have posted this in the wrong area.
But I will try to answer, I have never heard of this before in the US. I was in concrete construction, bridges, for 10+ years and never heard of a maximum rebar temperature. There are requirements for the concrete temperature.
I agree with DDBPE the concrete temperature will be your controlling factor. Under any bearable ambient temperature for rodbusters to be able to work in, the expansion of the steel will be negligible.