Final answer:
A concrete highway is built of slabs with gaps between them, known as expansion joints, to mitigate thermal expansion, reducing thermal stress and maintaining structural stability.
Step-by-step explanation:
A concrete highway is built of slabs to mitigate the issue of thermal expansion. When temperatures rise, materials such as concrete expand, and when they cool down, they contract. If concrete slabs are laid without any space between them, there's no room for this expansion, which can cause significant stress within the material, possibly leading to damage like cracking or buckling. To counteract this, engineers leave gaps between the slabs, known as expansion joints, allowing the concrete to expand and contract without causing thermal stress. These joints are a critical design feature in maintaining the structural stability of the roadway under varying temperatures.
Furthermore, the reinforcing rods often used in concrete, typically made of steel, have a coefficient of linear expansion almost equal to that of concrete, providing additional resilience to thermal stress. These measures ensure that, despite temperature changes from season to season, highways remain safe and intact for vehicular traffic.