Joints in concrete pavement

Fig.3 Location of joints in concrete pavement

• Joints are the discontinuities in the concrete pavement slab, and help to release stresses due to temperature variation, subgrade moisture variation, shrinkage of concrete etc.
• There are various types of joints in concrete pavement, e.g. contraction joint, construction joint, expansion joint and warping joint. Fig. 3 schematically shows position of various joints. The functions of these joints are as follows:
• Contraction joint: Contraction joints are provided along the transverse direction to take care of the contraction of concrete slab due to its natural shrinkage.
• Construction joint: Construction joints are provided whenever the construction work stops temporarily. The joint direction could be either along the transverse or longitudinal direction.
• Expansion joint: Expansion joints are provided along the transverse direction to allow movement (expansion/ contraction) of the concrete slab due to temperature and subgrade moisture variation.
• Warping joint: Warping joints are provided along the longitudinal direction to prevent warping of the concrete slab due to temperature and subgrade moisture variation.

These discontinuities (joints) could be extended to the full or partial depth of the slab. Sometimes iron bars are provided across the joints, the iron bars along the longitudinal joints are called tie bars andalong the transverse joints are called dowel bars.

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