**6. Conclusion**

The environmental conditions play an important role in compressive strength of concrete. Generally, the temperature during the curing time and humidity rate index value are among the most effective factors for achieving reliable concrete structure. It is shown that temperature if drops below the freezing condition, not only slows down the hydration process, but also reduces the durability of the concrete significantly. In general, for appropriately cured concrete, a temperature drop of 15° leads to 20%, and a 50% drop in humidity rate index ends up in 10% reduction in overall compressive strength, if the environmental conditions are not extreme. The concrete cured in significantly low temperature is not able to reach the same expected strength, whereas the higher cured temperature concrete could reach, regardless of the curing time. Therefore, it is recommend to pay close attention to curing procedures under extreme weather conditions. In addition, lower water-cement ratios have better performance under freeze-thaw cycles; however, in higher temperature condition, excessive heat is produced which could cause damages to other particles.
