What are Joints? How many types of Concrete Joints?

Concrete Joints

What are Joints? How many types of Concrete Joints?

Joints are Planned Breaks in concrete which allow RCC to move and prevent random cracking:

Joints may be classified mainly into four types.

Construction Joints:  These are joints provided at location where concrete work stop temporary, Ties bar are provided for good bonding between abutting sections of concrete. Rails is used to support the edges of the concrete joint and is normally running through the joints.

Expansion Joints: The joints which allows thermal expansion and contraction in elements without inducing stresses called expansion joints. The building longer than 40-45 m are generally provide with one or more expansion joints. Recommended center to center spacing is 30m. The joints are formed by providing gap between the building parts.

Isolation Joints: Totally separate a concrete element from another concrete element, or a fixed objects such as wall or column, so that each can move and not affect the other. The joints filling should be full depth and soft. It can be made of from foam rubber, cork, other material which is flexible mostly.

Contraction Joints: It is also called contraction control joints. Joints introduced in concrete structure to localize shrinkage movements. As the structure will shrink, the joints open slightly, and crack will occur in joints rather than in a random manner. These are grooved, formed, or sawed into sidewalks, driveways, pavements, floors. To minimize water entry and to prevent stones entry these joints may be filled with a flexible filler. Common fillers are Bitumen, Poly Sulphide, Poly Eurathe (PU).