How much strength could be lost if the cylinders are not kept between 60-80 degrees? If temperatures of the test cylinder storage area (cooler) are 90 degrees plus, what kind of strength loss can I expect to see in the breaks? I have some low breaks and I'm trying to figure out what is going on.

ANY HELP WOULD BE APPRECIATED!!! THANKS!!!!

Curing temperature for concrete cylinder specimens is reasonably critical. That's why, in the US and using ASTM standards, the range of curing temperatures is only about 6 degrees F.

When the curing temperature is higher than the standard (about 73F +/- 3F), you will get initially higher strengths but the ultimate strength can be lower than anticipated by strength gain curves for the mix design. If temperatures are lower than the standard curing temperature, the strength gain will be retarded.

If you are getting failing test results, I would look first at other issues, such as added water, improper mix design, poor sampling/testing procedures, etc. Temperature can be an issue, but the other issues are more common.