Expansion Joints- typically each 30m in larger structures like stadiums, bridges, shopping centres, carparks and airports.
Concrete expansion joints are used to separate slabs and concrete from other parts of the structure. Expansion joints allow independent movement between adjoining structural members, minimizing cracking when such movements are restrained.
These joints completely isolate the slab from a wall, column or footing
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, allow movement due to ground settlement or seismic activity and wind load. They are commonly found between sections of concrete structures- buildings, carparks, bridges, paving and walkways.
Before the advent of expansion joints, concrete plates and slabs would crack under the stress of movement.
Modern structures have to withstand horizontal, vertical and sheer movement. Expansion or movement joints are gaps between concrete elements to help absorb these loads. Cover plates are designed to produce a continuous surface for pedestrians or vehicles to pass safely over the surface, or to meet aesthetic, waterproofing, fireproofing, soundproofing, seismic or hazmat requirements.