How do you calculate expansion joints for concrete?

1. Concept of providing expansion joint gap between two concrete member is to avoid collision due to the thermal expansion of the members.
2. Expansion joint width for concrete member is calculated from the following equation.
3. W = L x T x C.
4. where,

How do you calculate expansion joints?

The total expansion change can be calculated as follows: Total expansion change in inches = (coefficient of thermal expansion) x (maximum temperature range) x (length of run in inches). Example: Total expansion change = (3.38 x 10-5 in./in./°F) x (120˚F) x (90ft x 12in./ft) = 4.38 in.

What size concrete slab needs an expansion joint?

Tips for placing concrete expansion joints Place joints around 30 times the slab thickness apart. So, for a slab which is 100mm thick, the joints should be placed around 3,000mm (3 metres) apart. Make sure joints are cut deep enough: they need to be at least a quarter of the thickness of the slab.

Do concrete slabs need expansion joints?

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.

What is the maximum length for expansion joint?

As per IS- 456:2000, structures exceeding 45m in length are designed with one or more expansion joint. As per IS 3414 which is a specific code for joints, it is mentioned as 30m. Expansion joint shall be so provided that the necessary movement occurs with a minimum resistant at joint.

What is the maximum spacing of expansion joints?

Maximum spacing of expansion joints range from 25-27 m in jointed reinforced concrete slabs, and from 40 m (for slabs <230 mm thick) to 60 m (for slabs >230 mm thick) in unreinforced concrete.

Is code for expansion joint?

As per IS 3414 which is a specific code for joints, it is mentioned as 30m. Expansion joint shall be so provided that the necessary movement occurs with a minimum resistant at joint.

How wide should an expansion joint be?

Expansion joints are created through the installation of a soft material, such as wood or foam, along the edges of concrete slabs. Joints should be at least 1/2-inch to 3/4-inch wide. Expansion joints should extend beyond the full depth of the concrete slab.

What is the interval of expansion joint for lengthy slab?

In brick or stone masonry expansion joints normally need not be necessary, except in the case of long walls exceeding 30 m in length; in such long walls the expansion joints shall be not less than 15 mm wide and shall be spaced not more than 30 m apart.

How far apart should expansion joints be on a concrete slab?

So for a 4 inch thick concrete slab, expansion joints should be no more than 8 to 12 feet apart. They should also be placed around structures that go deeper than the concrete slab, such as columns or walls.

What are expan­Sion joints?

Expan­sion joints are full-width cuts installed in pro­fes­sion­al con­crete floors and walls that allow the con­crete to expand and con­tract with­out crack­ing ran­dom­ly. They iso­late dif­fer­ent parts of the slab so that the whole slab can move with­out strain­ing cer­tain parts more than others.

How do you seal a concrete expansion joint?

Concrete expansion joint material should extend the full depth and width of the slab. Ideally, for expansion joints on the exterior of a structure, sealing these joint is preferable. A filler helps keep water and material from getting into the joint. I like to use a high quality urethane caulk.

What happens if there is no gap between concrete slabs?

Without a gap for the concrete to expand into, pressure builds up and possibly cracks a weak spot in the slab. Concrete moves with changes in temperature, from vibrations and movement in the earth. Joints also help keep concrete strong while the soil around it settles.