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Expansion and contraction joints in Rigid Pavements.

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Hi,

I have studied about the expansion and contraction joints. In the rigid pavements, like the cement concrete pavements, the cement slab is laid on the sub-grade. The concrete changes its volume with the change in the temperature.

If the natural temperature of the concrete is low i.e. concrete is laid down in the season of winter, then the chances are there that concrete will undergo expansion in the summer season.
Similarly, if the concrete is laid in the summer season then natural temperature of the concrete is already high, so the concrete will contract in the season of the winter.
Whether the concrete is going to expand or shrink, one has to provide the expansion or the contraction joints respectively.




Spacing of the expansion joints: The spacing of the expansion joint can be determined as below:             (expansion) e = co-efficient of thermal expansion * Ls * (t2-t1)
we provide width of the joints double then 'e', 50% allowance is provided for the filler material. 
Spacing …