effect of hot weather on concrete
40. any operation of concreting at atmospheric temperatures above0C can be placed under hot weather concreting. The effects of hot weather can be as follows:
Higher temperatures of fresh concrete result in more rapid hydration and reduced workability/quick setting. This reduces the handling time of concrete.
loss of power:
Concrete mixed, laid and cured at high temperatures typically develops a higher initial strength than concrete produced and cured at normal temperatures but strength is usually lower after 28 days or so.
Increased tendency to crack:
Rapid evaporation can cause the plastic to shrink and crack, and the subsequent cooling of the hardened concrete will create tensile stresses.
effect of cold weather on concrete
5. any concreting operation performed at a temperature lower than0C is called cold weather concreting. In the absence of special precautions, the effect of concreting in cold weather can be as follows:
When the temperature is around 5. falling till0C or below, the development of strength of concrete is retarded compared to development at normal temperature. Thus, the time period for deletion of form work has to be increased.
Solidification of concrete in the initial stage:-
Permanent damage can occur if concrete in its fresh state is exposed to solidification before some pre-hardening period. Concrete can suffer irreparable damage to its properties to such an extent that compressive strength may be as low as 50% of that required for normal temperature concrete.
Stress due to difference in temperature:-
Large temperature differences within a concrete member can promote cracking and adversely affect its durability.