Wednesday, April 10, 2013

Cement concrete pavements, pre-stressed pavements

Cement concrete pavements: 

  1. Cement concrete pavements comes under the category of the rigid pavement, due to the higher flexure strength of the concrete slab. 
  2. CC pavements have the longer life, because of the higher durability and high load carrying capacity.
  3. CC pavements require very less maintenance, so the maintenance cost is reduced.
  4. CC pavements have very good aesthetic appearance.

There are some disadvantages of the CC pavements,

  1. Initial cost of construction of the CC pavements is very high. 
  2. The provision of the joints is mandatory.
Pre-stressed concrete pavements:
Pre-stressed concrete pavements are constructed by using the pre-stressing techniques. The lower layer of the concrete slab is compressed from its normal state, with the help of the high tension cables.
The cable are laid on the position and are applied with the high tensile stresses on both the sides. When the bar is in the tension state, the concrete is poured in and is allowed to set. 
When the tension arrangement of the bars is removed the bars tries to regain its original shape, and it results in the induction of the bond stress between the concrete and the bars. So ultimately the concrete is subjected the compressible stress. When the loading is applied in the transverse direction from the top, the lower layers which are subjected to the tensile stresses, the tensile stresses are neutralized with the induced compressible stresses. So the cracks are not formed due to flexure.
So it is possible to construct a slab of length up to 120m without the transverse joints.

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