Question: What are harmful manifestations of plastic shrinkage of concrete in (a) reinforced columns and (b) slabs? Assuming that the air temperature is 21°C, the concrete temperature is 24°C, and the wind velocity is 30 km/h, determine the rate of evaporation. If this rate is too high from the standpoint of risk of plastic-shrinkage cracking, what precautionary measures would you take? Alternatively, determine the temperature to which concrete must be cooled to reduce the rate of evaporation to a safe limit.