What is the function of longitudinal joints in concrete road pavements?

Civil Engineering Tutorials

A longitudinal joint consists of a tie bar placed at the mid-depth of a concrete pavement and it is not intended for joint lateral movement.

Then one may doubt the reasons of placing longitudinal joints in concrete pavements. In fact, longitudinal joints are normally designed at a regular spacing e.g. 4.5m to accommodate the effect of differential settlement
of pavement foundation.

When uneven settlement occurs, the tie bars in longitudinal joints perform as hinges (Ministry of Transport (1955)) which allow for the settlement of concrete carriageway.

Moreover, it also serves to cater for the effect of warping of concrete due to moisture and temperature gradients by permission of a small amount of angular movement to occur so that stresses induced by restrained warping can be avoided.

Dowel bars are provided in longitudinal joints for the following reasons:

(i) In case of the occurrence of uneven settlement between adjacent panels, it helps to maintain a level surface by transfer of loads through dowel bars.

(ii) Keep the longitudinal joints close.

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