An expansion joint (or movement) joint is an assembly designed to hold parts together while
safely absorbing temperature-induced expansion and contraction of building materials, and
vibration, or to allow movement due to ground settlement or seismic activity. They are
commonly found between sections of buildings, bridges, sidewalks, railway tracks, piping
systems, ships, and other structures.
Building faces, concrete slabs, and pipelines expand and contract due to warming and cooling
from seasonal variation, or due to other heat sources. Before expansion joint gaps were built
into these structures, they would crack under the stress induced.