rubber expansion joints are 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 constructed in more elaborate ways, such as interlocking metal edges or 'spikes'. (Welcome to china rubber expansion joint manufacturer)