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What is a concrete expansion joint? A concrete expansion joint – or control joint – is a gap which allows the concrete to expand and contract as/when the temperature changes. It forms a break between the concrete and other parts of a structure to allow movement without causing stress, which can lead to cracking.
Do I need an expansion joint in concrete slab?
Expansion joints are virtually never needed with interior slabs, because the concrete doesn’t expand that much—it never gets that hot. Expansion joints in concrete pavement are also seldom needed, since the contraction joints open enough (from drying shrinkage) to account for temperature expansion.
When Should expansion joints be used in concrete?
Expansion joints are put in place before the concrete is poured. Expansion joints are used to allow the slab to move and not put stress on whatever it abuts. These joint are placed where a slab meets a building, where a slab meets another slab, and where a pool deck meets the coping.
What happens if you don’t put expansion joints in concrete?
If you have a concrete floor in your commercial building, you know expansion joints are necessary to allow for the natural expansion and contraction that occurs from temperature changes. Without these joints, large cracks can travel across your floor, creating costly damage.
Where are expansion joints required?
Expansion joints occur through all parts of a structure to provide complete separation – through floors, walls, ceilings, and roofs (interior & exterior).
What do you use for expansion joints in concrete?
There are two types of expansion joint filler, foam and fibreboard. When working with concrete you should use fibreboard, which offers flexibility across the surface of concrete, allowing movement that will prevent cracking.
What material is used for expansion joints in concrete?
Minimize Concrete Cracking and Damage with Expansion Joints. ASPHALT EXPANSION JOINT is composed of a blend of asphalts, vegetable fibers, and mineral fillers formed under heat and pressure between two asphalt-saturated liners. It is waterproof, permanent, flexible, and self-sealing.
Do house slabs have expansion joints?
Expansion joints separate the slab from structures such as foundation walls, footings, and structural support columns, and allow the slab to move unrestrained both horizontally and vertically.
What is the difference between a control joint and an expansion joint?
In building materials, a control joint is used to control cracking while an expansion joint is designed to handle structural movement. By contrast, an expansion joint (or movement joint) is sized and formed at a width prescribed by the building design team and sealed and bridged later by an expansion joint system.
How big of a slab can you pour without expansion joints?
Rule #1 – Keep joints as square as possible. Rule #2 – In order to prevent intermediate cracking, space joints (in feet) no more than 2 – 3 times the slab thickness (in inches).
How often are expansion joints needed?
Usually, expansion joints should be no farther apart than 2 to 3 times (in feet) the total width of the concrete (in inches). So for a 4 inch thick concrete slab, expansion joints should be no more than 8 to 12 feet apart.
How long do expansion joints last?
When expansion joints are designed, applied, and installed correctly, it is not unusual to achieve a service life of 15-20 years in most industrial applications.
How deep should expansion joints be cut in concrete?
A good rule of thumb is to cut the joints one-quarter to one-third the slab thickness. For a 6-inch-thick slab, that means cutting 1 1/2 to 2 inches deep. Ensure that the saw cut depth meets the structural engineering specifications.
Can we avoid expansion joint?
Expansion joint shall be so provided that the necessary movement occurs with a minimum resistant at joint. The structures adjacent to joint should be preferably supported on separate columns. Reinforcement shall not extend across the joint.
How thick is an expansion joint?
Expansion joint thickness can vary from . 010 inches to . 125 inches thick depending upon the design requirements for your application.
How much do expansion joints cost?
The price to repair expansion joints and control joints greatly depends on how bad the damage is. Preventative joint filling can cost between $1.50 and $3 per lineal foot, but once expansion joint repair or control joint repair is required, the costs can vary from $15 – $100 per lineal foot of joints.
What is the black stuff between concrete slabs?
An expansion joint is a material placed in the cracks (or joints) between concrete slabs to protect the slabs from cracking when they contract and expand as the temperature changes. This material acts as a shock absorber, absorbing the stress from the slab’s movement.
Should expansion joints be filled?
Just remember that expansion joints should always be sealed and filled with a flexible joint sealer and never epoxied or coated over. Contraction joints can be filled in the same manner after a coating or sealer is applied if you desire.
What is the best expansion joint for concrete?
Why Silicone is the Best Expansion Joint Filler First and foremost, it is flexible and durable, allowing it to accommodate the natural expansion and contraction of the slab without cracking or breaking its seal.
Can you cut expansion joints in concrete?
Joints may also be sawed into the hardened concrete surface. For most concrete mixtures, this means sawing should be completed within the first six to 18 hours and never delayed more than 24 hours. Early-entry saws are available which may allow cutting to begin within a few hours after placement.
Do I need expansion joints in concrete driveway?
Concrete expansion joints are important for your sidewalk or driveway. Keeping your joints watertight will prevent moisture from seeping under concrete pads and causing them to heave or sink.
Do foundations have expansion joints?
Expansion joints are not provided in foundation because foundation is deep underground where there is no temperature difference during summer and winter.
How does an expansion joint work?
Expansion joints are installed in a piping system to absorb vibration and shock. They also have advantages such as reducing the noise and compensate caused by misalignment. If the temperature of the pipe increases, the metal expansion joint compresses to compensate for the movement and alleviate stress from the pipe.
