Cold weather concreting

The normal procedure adopt for concreting in fear weather will not be carried for concreting when the temperature in low or below the freezing point. The production of concreting in cold weather introduce special and particular problem such as delay in setting and hardening. Damage to concrete in plastic plastic condition when exposed to below freezing point owing to the formation of ice lenses, therefor it is essential to maintain the temperature of concrete positively above 0oC possibly at much higher temperature.

Effect of cold weather concrete

1) concreting operation done at less than 5oC are called as cold weather concrete.

2) Due to low temperature the problem are mainly because of the slow development of strength. The concrete remain in the plastic stage.for a longer period and can be easily damage.

3) When concrete exposed to cold ice lenses are formed and water is pores expand while freezing.

4) Alternate freezing and thawing can cause damage to the pores structure in the gel.

5) At low temperature development of concrete strength is retarded as compare with the strength development at normal temperature.

6) The setting period before removal of form work is thus increase.

7) When plastic concrete expose to freezing temperature it may suffer permanent damage.

8) Because of freezing and thawing reduce durability of concrete.

9) Such situation can be occur in freezing climate at the time of removal of formwork.

10) Stress due to temperature differential cause uneven expansion and cracking.

Effect of Hot weather concrete-

1) any operation of concreting done above $40^oC$ atmospheric pressure is called hot weather concrete.

2) The climatic factor which cause harmful effect on concrete during hot weather are a high ambient temperature and reduce relative humidity.

3) The effect of this factor are even worse if there is wind of high velocity caused due to high climate.

4) A high temperature result in a more rapid hydration leading to accelerate setting.

5) This reduce the handling time and also lower the strength of hardened concrete.

6) The workability of concrete is decreased and hence adjustment of mix proportion or design. It will ultimately affect the strength of concrete.