measuring the fresh mix temperature, and what if the temperature was high ?

According to the ACI Code Fresh mix shouldn't be more than 32°C.
In the picture above the termo-meter which is used to measure the temperature of the fresh mix.

What should I do if the temperature more than 32°C ?!

You shouldn't use this mix if the temperature more than 32°C , but if it was near 32 degrees you should put a wet canvas with very cold water. Moreover, the concrete should be sprayed with water daily for a week with cold water.