Do expansion joints need to be filled?

Just remember that expansion joints should always be sealed and filled with a flexible joint sealer and never be epoxied or coated over. Contraction joints can be filled in the same manner after a coating or sealer is applied.

Considering this, should you caulk driveway expansion joints?

Cracks in the expansion joints in a concrete driveway can cause problems if they're not sealed properly. Cracks can allow water to seep under the concrete, creating a void that can cause the concrete to sink. The caulk will seal the expansion joint and keep water out.

Subsequently, question is, when should you use expansion joints in concrete? The goal of the control joint is to allow the slab to crack, during expansion and contraction, in a known location and in a straight line. 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.

Also Know, how do you fix an expansion joint?

How to Replace Concrete Expansion Joints

Sweep away any dirt and debris from the area.
Dig out and remove all the old material that's in the joints with a putty knife.
With a wet-dry vacuum, clean out the joints between the slabs very well.
Apply a bonding adhesive, usually epoxy, into the joints with a brush.
Insert foam backer rod.
Cover and seal the joint.

How do you fill gaps between driveway slabs?

The best way to repair your expansion gap is to use purpose-designed foam backer rods and self-leveling caulk. Both materials are available in most home improvement stores. Cut your foam backer rods to the proper length for your expansion gap and press them into the gap.

26 Related Question Answers Found

How do you fill gaps between concrete slabs?

Scrape off any old patching tar with a stiff putty knife and remove residual tar or asphalt compounds with mineral spirits and gentle scrubbing with a wire brush. Dig a 4-inch wide trench along the sides of the slabs from the crack or gap closest to the house all the way down to the street or sidewalk.

Are concrete expansion joints necessary?

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.

Should concrete control joints be caulked?

Control joints or saw cuts should be addressed the same as above. The control joint can be filled with backer rod or even sand. Filling the saw cut is mandatory as control joints are 1/4 the thickness of the concrete. On a 4″ slab, that is a 1″ deep saw cut and nobody want to use that much caulking.

How big can a concrete slab be without expansion joints?

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.

What causes concrete driveways to crack?

Contractors who install an improper base or subbase, usually to save money or time, often use a light material like sand or dirt. When this loose material gets moist, the freeze-thaw cycles cause the material to expand and contract, putting uneven pressure on the driveway and causing the concrete or asphalt to crack.

What is the best concrete caulk?

Silicone represents another popular material to use as a concrete caulk. It does not degrade as fast as the organic urethane caulks, and it remains flexible yet sturdy in its hold. One of the best uses for silicone caulk involves filling the gaps between concrete and other materials, such as brick, wood or metal.

How do you fix a large crack in a concrete driveway?

How to Repair Wide Concrete Cracks

Chisel the crack with a hammer and masonry chisel to widen the base of the crack and to dislodge any loose material from the old concrete.
Remove all debris from the crack, using a wire brush.
Remove all water and debris from the crack with a wet/dry shop vacuum or a brush.

What does backer rod look like?

QUIKRETE® Backer Rod is an extruded round, closed cell, low density polyethylene foam material with a skin-like outer texture. It is highly flexible and compressible for easy installation. QUIKRETE® Backer Rod is chemically inert and will resist oil, gasoline and most other solvents.

What is self leveling sealant?

Self Leveling Sealant is a single component, self-leveling, premium grade polyurethane sealant with an accelerated curing capacity. It seals horizontal expansion joints in concrete and cementitious slabs requiring no tooling.

Where do concrete control joints go?

Space joints (in feet) no more than 2-3 times the slab thickness (in inches). A 4" slab should have joints 8-12 feet apart. Cut joints deep enough. Cut joints 25% of the depth of the slab.

What is the difference between expansion joints and control joints?

A control joint is used to reduce the occurrence of shrinkage in concrete, and it is usually a continuous, vertical joint filled with mortar. An expansion joint is a continuous or horizontal joint.

Does concrete shrink or expand when it dries?

A.: When it first dries, concrete shrinks and undergoes structural alterations that make some of the shrinkage irreversible. Thus, even if it is later resaturated, the initial drying shrinkage isn't fully recovered. However, concrete does indeed expand when it gets hot or when the moisture content changes.

How do you install expansion joints?

INSTALLATION

Apply Lubricant. Rubber expansion joints face flanges may be painted with a solution of graphite in water or glycerin to prevent adherence of joint to pipe flanges.
Insert Expansion Joints into Position. Do not use gaskets for AMS/AMT series.
Insert Bolts.
Tighten Bolts.
Control Rods.
Additional Tips.

How do you attach concrete to concrete?

A bonding agent (bonding adhesive) needs to be painted onto the existing concrete first to ensure that the fresh concrete will successfully adhere. This is also true of floor repairs, if concrete is used to fill gaps caused by damage. The new won't adhere to the old without the help of a bonding adhesive.

Why do they cut lines in concrete?

If you're using concrete to make a sidewalk, the shrinking concrete will cause cracks to appear as it dries. To prevent sidewalks from cracking in random spots and breaking apart, builders make lines in sidewalks. Of course, they don't just call them lines. The technical term for sidewalk lines is contraction joints.

Where are expansion joints used?

Concrete expansion joints are used to separate slabs and concrete from other parts of the structure. Expansion joints allow independent movement between adjoining structural members, minimizing cracking when such movements are restrained.