rubber expansion joint is cut into the concrete or asphalt to help with expansion and contraction of the material through the change in temperature, or due to movement of the road or bridge. The joints are cut into the structure at regular intervals to prevent it cracking or splitting. Road expansion joints can be sealed with hot tar, cold sealant (such as silicone), or compression sealant (such as rubber); or in other more elaborate ways, such as in the photo to the right.