Question

What is function of longitudinal joints in concrete road pavements?

Answer

A longitudinal joint consists of a tie bar located at mid-depth of a concrete pavement and it is not intended for joint lateral movement. Then one might doubt the reasons of placing longitudinal joints in concrete pavements. In fact, longitudinal joints are usually designed at a regular spacing as in 4.5meter to accommodate effect of differential settlement of pavement foundation. At what time uneven settlement occurs, tie bars in longitudinal joints perform as hinges that allow for settlement of concrete carriageway. Furthermore, it also serves to cater for effect of warping of concrete due to moisture and temperature gradients by permission of a small quantity of angular movement to occur consequently that stresses induced by restrained warping can be avoided.

Dowel the bars are provided in longitudinal joints for following causes-

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

(ii) Keep longitudinal joints close.