What is a slip joint in concrete?

Slip joints are joints in construction which provide sliding movement of one component over another with the minimum of restraint at the interface of the two components. In the civil engineering world, slip joints are usually provided to work as a movement joint.

Why are joints placed in concrete slabs?

Contraction/control joints are placed in concrete slabs to control random cracking. When shrinkage is restrained by contact with supporting soils, granular fill, adjoining structures, or reinforcement within the concrete, tensile stresses develop within the concrete section.

Why do we need expansion joint in slab?

Expansion joints are placed in concrete to prevent expansive cracks formed due to temperature change. Concrete undergoes expansion due to high temperature when in a confined boundary which leads to cracks.

What is the joint gap provided in slabs?

What is the gap provided in slabs? Explanation: The slabs are provided with a gap of usually 20 mm for expansion in summer season.

What is the purpose of a slip joint?

Slip joints in large structures are used to allow independent motion of large components while enabling them to be joined in some way.

Why are joints needed?

Joints are where two bones meet. They make the skeleton flexible — without them, movement would be impossible. Joints allow our bodies to move in many ways.

What is difference between construction joint and expansion joint?

A construction joint occurs when there are multiple concrete placements. An expansion joint is used in concrete and steel. It can occur between different days of concrete placements. An expansion joint allows the concrete or steel to expand or contract with daily temperature variations.

Do you need expansion joints in concrete slabs?

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.

Why contraction joints are provided?

Need of Contraction joint in Concrete Concrete tends to shrink or reduce in size when it starts hardening. This shrinkage of concrete creates tensile stresses in the concrete which develops the minute cracks at the weak plane. To prevent such cracks, contraction joints must be installed at appropriate intervals.

Why expansion joints are used in pipeline?

As pipeline expansion joints are designed to safely absorb the dimensional changes of steel pipe systems and ducts. Expansion joints also offer the advantage of reducing stresses in pipe systems generated by thermal expansion, and reduce pipe loads at connections to sensitive equipment such as pumps and steam turbines.

What is the purpose of slip joint in propeller shaft?

A slip joint is provided between universal joint and propeller shaft to adjust for any change in length. Final drive is the last stage of power transfer from propeller shaft to rear (or front if – automobile is front wheel driven) axles and then to wheels.

What is the purpose of joints in a concrete slab?

They are used in between pours and are designed to allow slab movement or transfer load from one pour to another. The location of construction joints should be planned to minimize cracking in concrete slabs. It may be good practice to bond or continue reinforcement through a construction joint.

What happens if you put dowels in concrete slabs?

If these dowels are firmly fixed in both the slabs, it will not allow slabs to contract or expand when weather turns cold or hot. This will cause temperature stresses to develop in the slabs and concrete adjacent to the joint will crack. Concrete, like all other materials, expand when heated and contract when cooled.

What is the difference between contraction and expansion joints in concrete?

Usually any slab exceeding 14–15 m of span need expansion joints. Like concrete roads, building slab etc. The expansion joint is full depth joint where as contraction joint is not. Dowl bars are used for load transfer between the slabs. ( Thanks to equal strain of steel and concrete)

Can you continue reinforcement through a construction joint?

It may be good practice to bond or continue reinforcement through a construction joint. Concrete, when drying, has a natural tendency to shrink. For large pours or long narrow pours, like sidewalks, installing construction joints at preplanned locations will help minimize random cracking in the concrete.

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