What factors are important during hot - and cold - weather concrete placement?

Factors important during Placement of concrete in hot weather:

• Effect of temperature, air humidity and wind has a large impact on placing a concrete in hot weather.
• Hydration of the cement occurs easily during hot weather because the water evaporates from the surface faster in high temperature.
• Increase in relative humidity will decrease higher temperatures.
• Work should be completed by avoiding delays of placing the concrete and finishing and curing of the concrete.
• Placement of concrete should be done in early morning or in evening.
• Sunshades, wind breaks should be provided in proper way.

Factors important during Placement of concrete in cold weather:

• To prevent concrete from carbonation calcium carbonate can be used.
• The average daily temperature of air should be less than 40 deg F.
• The freezing temperature of the concrete should be approximately 28 deg F.
• Admixtures can be used to increase the rate of setting when the temperature of the concrete reaches 40 deg F.
• Concrete should be protected from the lower temperature and action of freezing.
• The compressive strength of the concrete during cold weather should be 2500 psi.