Question
What are the functions components of a typical expansion joint?

Answer
In a characteristic expansion joint, it normally contains following mechanism-joint sealant, joint filler, dowel bar, PVC dowel sleeve, bond breaker tape and cradle bent.

Joint sealant- it seals joint width and prevents water and dirt from entering joint and causing dowel bar corrosion and an unexpected joint stress resulting from controlled movement.

Joint filler- it is compressible so a joint can expand liberally without constraint. Someone might doubt that even without its presence, joint can expand liberally. In fact, its presence is essential because it serves purpose of space occupation such that even if dirt and rubbish are intruded in joint, there is no gap left for their accommodation.