Expansion Joints in Concrete

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Picture above are of an expansion joint in concrete pavement in which deformed bar reinforcement (rebar) was used in lieu of smooth bar dowels to cross over the joint. As the temperature goes from cold to hot, the concrete pavement will increase in volume and will subsequently decrease in volume when transitioning from hot to cold.

Smooth bar dowels are important at expansion joints so that this volume change (which primarily will occur along the longitudinal axis of the pavement) is not restricted.

In this case, the tension induced into the rebar dowel was large enough to plastically deform and ultimately fracture the rebar (would take approximately 20,000 pounds to rupture this #5 bar).