What Are Expansion Joints?

By Author: MBT
Total Articles: 6
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In building construction, an expansion joint is a mid-structure separation designed to relieve stress on building materials caused by building movement induced by:

thermal expansion and contraction caused by temperature changes,
sway caused by wind
seismic events
static load deflection
live load deflection

Because the joint bisects the entire structure, it marks a gap through all building assemblies–walls; decks; plazas or split-slab concourses; foundation floors and walls; roofs, planters, and green roofs; fire-rated demising walls and floors; interior floors; etc.  This gap must be filled to restore the waterproofing, fire proofing, sound proofing, air barrier, roof membrane, trafficable surface and other functions of the building elements it bisects.
Some of the expansion joints are:
Movement expansion joints are designed in a way that it holds parts together safely, absorbs temperature and contraction of the building, ...
... and protects from seismic activity. These are commonly found between sections of buildings, sidewalks, piping systems and so on places.
Bridge expansion joints are generally used in construction of bridges. It stops the bridge from bending out of place in extreme conditions.
Seismic expansion joints create a separation between adjacent buildings or parts of buildings and wings. Seismic expansion joints have complex design, they adequately sealed from weather and safe to walk on and maintain the fire rating of floor, roof and wall systems.
Fire rated expansion joints prevent the spread of fire and interrupt the fire. They are necessary in order to maintain building's and block's safety.
Control expansion joints are used to control cracking. It can be formed during placement of the building material or cut after the material is placed. Control expansion joints are excellent resistance to grease, oil and cleaning chemicals.
Heavy Duty expansion joints are used for ceramic tiles to heavy mechanical loads. It is specially designed to absorb heavy traffic loads. It is optimal suitability for industrial use.
Quiet joints is a mass loaded sound, draft, heat, cold and dust blocking joint filter for interior, non-moving joints and gaps. Quiet joint are used in end of partition to the window, wall and head of the wall. It can also be used to fill construction-created voids and gaps.
Roof expansion joint is a patented dual-seal, extruded thermoplastic rubber system for sealing expansion joints in roofs.
Trench Access covers are individual square units for direct access to maintenance valves, joinery and controls. It is linear and can run in multiple directions. It is easy to access sub-floor utilities and services for maintenance of plumbing, electrical and other buried equipment in buildings like hospitals, schools, laboratories etc.
Why to seal an expansion joint?

Joint arris protection: Exposed edges of concrete slabs are vulnerable to damage caused by vehicle wheels passing across the joint, particularly at 90⁰, and particularly when the wheels are small and hard.  Repeated traffic can cause the joint arris to spall, which makes it harder for vehicles to cross smoothly and safely, and causes premature vehicle damage.
To prevent chemical infiltration: If there is a risk of chemicals permeating into the ground through the joint gap, then sealing it is essential.
Health & safety: Open joints can attract dirt and debris, which in some buildings can be unhygienic and unattractive.  Unsealed joints can also be a hazard for pedestrians – eg, in DIY stores where customers may be wearing high heeled shoes, or sandals, or there may be children whose small feet could trip on the joint.

Neoprene foam sealant:
Neoprene foam is a closed cell foam sealant. It is impermeable to air and water, and it providing superior sealing against ingress of liquids, including of oils and chemicals. It is used for sealing gasketing and insulating applications.
 
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