how do you install an expansion joint in concrete

How to Install Expansion Joints in a Concrete Driveway

• Prepare for Your Joint Installation. When preparing to pour your slab, use ready-made joints. They will need to be the...
• Add Joints During Slab Pour. The easiest way to add expansion joints is to do it during the pouring of your cement slab.
• Use a Joint Trowel. When pouring and troweling your concrete slab, use a...

Full Answer

How do you add expansion joints to a concrete slab?

They will need to be the same height as the thickness of the slab you'll be pouring. The same is true with wood joints. Cut them, or buy them, at a height that will match the thickness of your concrete. The easiest way to add expansion joints is to do it during the pouring of your cement slab.

How do expexpansion joints work in concrete?

Expansion joints are used to relieve this pressure. The concrete itself is super stiff and doesn’t contain any elasticity. It’s not a forgiving material. Expansion and contraction pressures inside the concrete build as the temperature and weather changes. This pressure relieves itself by finding weak spots in the concrete and cracking.

What should I consider when using expansion joints?

When it comes to using expansion joints, keep in mind that they’re visible all the time. There are a few things you should think about other than the function purpose of the joint. First and foremost, people want they’re concrete work to look nice. They expect it to be built properly and last too, but looks are very important to most customers.

What is the purpose of expansion joints in brick construction?

Masonry Expansion Joints. These are primarily used in laying bricks. Including a joint in place of mortar helps with the movement of the bricks. Just like a bridge, buildings move. If the concrete can’t move with it you’ll get cracks.

How do you put expansion joints in concrete?

0:242:10How to make concrete expansion joints - YouTubeYouTubeStart of suggested clipEnd of suggested clipAnd then they use long grooving tools to get these wonderful expansion joints nice and flat. AndMoreAnd then they use long grooving tools to get these wonderful expansion joints nice and flat. And straight down the length of the concrete. They do use these tools to get a rough expansion joint.

Where do you put expansion joints?

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.

Do you need to put expansion joints in concrete?

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.

How deep does a concrete expansion joint need to be?

Tips for placing concrete expansion joints Make sure joints are cut deep enough: they need to be at least a quarter of the thickness of the slab. For a 100mm slab, cut the joints at least 25mm deep. If you're cutting joints after the concrete has been poured, don't leave it too long.

What happens if you don't put expansion joints in concrete?

Concrete expansion joints give the slabs just enough room to move which helps prevent cracks & buckling. Without these joints, even a little movement creates pressure and stress on the concrete. Eventually weak spots can crack or buckle.

What is the distance between expansion joints?

Expansion joint spacing is dictated by the amount of movement that can be tolerated, plus the allowable stresses and/or capacity of the members. As with contraction joints, rules of thumb have been developed (Table 3). These range from 30 to 400 ft (9 to 122 m) depending on the type of structure.

What is the best expansion joint for concrete?

Silicone provides an excellent alternative to the three expansion joint fillers above, and for a few reasons. 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.

Should you caulk expansion joints in concrete?

Caulking Concrete Cracks and Expansion Joints Caulking the joints and cracks is the best way to stop this from happening. Even expansion joints in your concrete driveway should be caulked. They can be the biggest culprit of water under your slabs.

How many times do you float concrete?

Push the bull float in one direction only across the concrete, keeping its front edge slightly above the surface by raising or lowering the handle. Two or three times is enough. Don't overwork the concrete or you'll weaken it by drawing too much sand and cement to the surface.

Where do you cut expansion joints in concrete?

It's recommended that you start cutting control joints on or at the centre of column lines. Joints should be spaced at 24 to 35 times the slab thickness, however, the exact spacing should be decided by an engineer familiar with the individual project.

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.

Are expansion joints supposed to crack?

Concrete Expansion Joint Repair: Causes and Effects Without these joints, large cracks can travel across your floor, creating costly damage. While your concrete floor expansion joints are designed to absorb and dissipate the stress from expansion, in extreme cases, the joints themselves can crack.

How far apart should expansion joints be in Blockwork?

– 12 metresThe general thinking in the construction sector is that your expansion joint will be spaced at approximately 10 – 12 metres. This joint will be continuous for the full height of the brickwork or blockwork, from floor to roof of a house, for instance.

How long can a wall be without an expansion joint?

Movement joints in internal walls are not normally necessary for single dwellings unless the walls are straight and unbroken and over 6m long, in which case the block manufacturer's recommendations should be adopted.

How far apart should expansion joints be in brickwork?

approximately 10 - 12 metresIn general, experience suggests that movement joints in clay brickwork should be spaced at approximately 10 - 12 metres. PD 6697 states that in no case should joints exceed 15 metres and the spacing of the first joint from an internal or external angle should not exceed half of the general spacing.

Do I need an expansion joint in my wall?

Expansion joints are required in masonry walls. Typically these are at 6 m centres for concrete blockwork and 12 m centres for brickwork. Suitable materials must be used in expansion joints to allow adequate movement of the masonry.

How to use expansion joints?

Laying a concrete driveway is a typical project often requiring the use of expansions joints, depending on the size of the area to be covered.

Why are expansion joints important?

They are also installed to absorb vibration, hold parts together or allow those parts to move as the ground settles or if there is an earthquake. Thankfully, there are few earthquakes in the UK, however, expansion joints are an important element in construction using concrete for all the other reasons.

What causes cracks in concrete?

However, this also means tensile pressure is put through the concrete as it shrinks, which can cause cracks.

What type of joint is used to fill concrete?

An expansion joint that can add flexibility and buffer the movement in the concrete is therefore the best solution. 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.

Does concrete shrink in heat?

As with wood, concrete can expand and shrink in heat. There is also shrinkage after the concrete has hardened. By placing expansion joints in a grid form across an expanse of concrete pouring, in positions where cracks can be expected to occur, cracks, if they occur, are held below the surface, remaining superficial and mostly invisible.

Can cracks in a house cause structural problems?

Remember, any cracking can cause structural problems in your build. However, more likely, it will look particularly unsightly. This obvious appearance of cracks could compromise the end finish of your build.

How thick is a concrete sidewalk?

Cut them to be the same height as the thickness of your concrete. So for a 4″ thick sidewalk you’ll cut 4″ expansion joints. As you pour each slab of concrete, stop and place your joint in between each slab.

What is pre-molded joint filler?

Pre-molded joint filler should be used to separate slabs from building walls and footings. If the slab contains wire mesh, I recommend you stop the mesh at the joint. Joints should be spaced so that the concrete sections are even and uniform. It’s recommended to have concrete joints along column lines.

Why do concrete slabs crack?

If a concrete slab is too big and doesn’t have expansion joints, when the structure shifts, vibrates, expands or contracts, the stress and pressure finds relief by cracking. Expansion joints are used to prevent these cracks.

Why do you need an expansion joint in a concrete slab?

The purpose of having an expansion joint in a concrete slab is to prevent cracks and buckling. Joints prevent damage to the slab which makes them last longer and look better. By including expansion joints, there’s a place for the concrete to go when it moves.

What is joint in concrete?

Joints are used in areas where two slabs of concrete meet, when a slab meets another concrete structure like a wall or when a span of concrete is overly long. For example, a 100 ft. concrete sidewalk wouldn’t be poured in one long slab. You’d get lots of cracks. Rather, we cut expansion joints which breaks the sidewalk into smaller pieces. These smaller slabs of concrete can move much easier which helps prevent cracks and buckling.

Why does concrete expand?

Concrete routinely expands and contracts as it changes temperature. It can also shift a little with the movement of the earth. Concrete expansion joints give the slabs just enough room to move which helps prevent cracks & buckling. Without these joints, even a little movement creates pressure and stress on the concrete.

What is an expansion joint?

Expansion joints are filled with a flexible material that runs along and inside the joint or gap in slabs and other concrete structures. An expansion joint is designed to absorb the expansion and contraction of concrete that naturally occurs due to change in temperatures.

Do concrete driveways need expansion joints?

Every concrete slab, inside (basements, garages, etc.) or outside ( driveways, patios, entries, etc.) are required to have joints every eight feet horizontally and vertically. Expansion Joints provide space between concrete slabs as a buffer for expansion on hot days and contraction when it is cold.

How far apart should expansion joints be in concrete driveway?

So for a 4 inch thick concrete slab, expansion joints should be no more than 8 to 12 feet apart.

Should you caulk concrete expansion joints?

Even expansion joints in your concrete driveway should be caulked. They can be the biggest culprit of water under your slabs. Notice how the caulking is slightly lower than the concrete slab around it. This protects the caulk from wear and tear of people walking and driving over it.

Where do you put expansion joints 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 is the difference between expansion joints and control joints?

A control joint is a continuous vertical joint filled with mortar , but with a bond breaker on one side so that tensile stress cannot develop across the joint. An expansion joint is a continuous vertical or horizontal joint, left completely free of mortar and filled with elastomeric sealant to keep it watertight.

What is the best PSI for a concrete driveway?

A strength of 4,000 psi (pounds per square inch) after a one month cure is the industry minimum for concrete driveways, slabs and sidewalks. However, 4,500 psi as the ideal. According to guidelines published by AsktheBuilder.com, a home foundation requires a thicker pour of 8-10 inches and a psi of 3,500- 4,000.

Do you need expansion joints in a garage floor?

But the same thing happens with concrete. That’s why it is necessary to include expansion joints along the edges of the concrete garage floor as well as around posts or other protrusions in the slab.

How to seal a backer rod?

Measure the amount of backer rod you need and cut off a piece that's the right size. Push the strip into the joint with a putty knife, making sure to push it in all the way. Cover and seal the joint. Apply a liberal layer of self-leveling urethane sealant.

What is an expansion joint?

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. After a while, the expansion joint can dry out and won't absorb ...

How to clean joints between slabs?

With a wet-dry vacuum, clean out the joints between the slabs very well.

How long does it take for a shock absorber to dry?

Let the adhesive dry for about 10 to 15 minutes. Don't leave the adhesive for any longer than that because it should be sticky to touch, not completely dry. Insert foam backer rod. This will be your new shock absorber. Measure the amount of backer rod you need and cut off a piece that's the right size.