Special problems are faced in making, placing and concrete in hot weather. Concrete placed at an compacting atmospheric temperature above 400C is considered as hot weather atmospheric creating. In hot weather concreting following properties of concrete and problems must be kept in mind.
(i) Rapid rate of hydration of cement, quick setting and Carly stiffening.
(ii) Rapid evaporation of mixing water.
(iii) Greater plastic shrinkage.
(iv) Less time for finishing.
(v) Reduced relative humidity.
(vi) Absorption of water from the concrete by the subgrade and form work.
(vii) Difficulty in continuous and uninterrupted curing.
(viii) Difficulty in incorporation of air entrainment.
The effect of above discussed points should be fully identified and care must be taken to make the concrete strong and durable.
Precautions: (1) The temperature of the ingredients of concrete should be kept as low as possible.
(2) Aggregates should be stockpiled in shade and sprinkled with water
(3) Temperature of mixing water should be kept as low as possible. Preferably mixing water should be cold and this will effect good reduction of concrete temperature.
