Concrete In An Above Freezing Temperature example essay topic

Cold Weather Concrete There are many challenges that come along with placing concrete. One of which is doing so in cold weather. There have been a few procedures that have been developed to help place the concrete in cold weather. The first development to place concrete in cold weather is by changing the local temperature in the surrounding area, the second is adding chemicals to the concrete, and the third is to mix the concrete in an above freezing temperature and waiting until it has achieved a desired strength that won't be damaged by the freezing temperatures.

The first method of placing concrete in cold weather has a few restrictions. When one actually tries to change the surrounding temperature one is limited to the volume of the concrete. The surrounding area is warmed by the aid of insulted forms. The forms help contain the heat produced in the concrete by the hydrating pumps.

Another method for heating the concrete is by placing a heated structure around the placed concrete. This structure must be left in place until the concrete is exposed to the freezing temperature without compromising its strength. The second method is the more popular of the two. The cost of heating the concrete is minimal; the structure can be used again, unlike the forms, which must be thrown out.

The second method for placing concrete in cold weather is the procedure of placing chemicals in to the concrete. There are numerous chemicals that can be added to the concrete. Some additives increase the rate at which the concrete cures or hydrates, known as accelerators. The accelerators make it possible for the concrete to cure before the cold weather has a chance to affect the concrete. The second additives used to help aid the curing of concrete are antifreezes.

The antifreeze lowers the temperature at which the water in the concrete will freeze. The antifreeze additives are generally soluble salts that react wit the water causing it to freeze at a lower temperature. This reaction is somewhat like the reaction that occurs when salt is placed on the roads to thaw snow and ice. The only difference is that the chemical base is chloride.

The third additive is called air entrainment. This process adds tiny bubbles to the concrete. This process is used in areas that are prone to high freeze thaw ratio. The tiny bubbles act as void areas when the concrete is curing. When the concrete freezes the water in the concrete causes stress. The bubbles provide an area for the concrete to go, in turn relieving the stress within the concrete.

Relieving the stress within the concrete helps prevent cracking, and failure within the structure. Although adding bubble to the concrete reduces its strength, its effects are minimal. Failure would be far greater if the concrete were to fail because of outside freezing temperatures. The third method for placing concrete in cold weather is regulated set concrete.

The concrete is mixed at an above freezing temperature and the hydration process is soon started. This method is based on the theory that heat is releases during the hydration process this heat makes it able for the hydration process to continue. The hydration process is continues until the concrete has reach a strength that is able to resist freezing temperatures. This process is comparable to high early concrete.

The usually Portland cement to not used, instead regulated set cement is used. The cement is ground very fine, and it contains gypsum, which regulates the rate of setting. One achievement that has been made possible by this method is the placement if of concrete when the thermometer showed a reading of negative eight degrees farenheight. The antifreeze additives are generally soluble salts that react with the water causing it to freeze at a lower temperature. One achievement that has been made possible by this method is the placement if of concrete when the thermometer showed a reading of negative eight degrees farenheight Cold Weather Concrete There are many challenges that come along with placing concrete.