The expansion joint gap depends on the type of slab like floating slab floor vehicle pavement sidewalk or monolithic slab foundation.
Expansion joints concrete slabs spacing.
Joints are commonly spaced at distances equal to 24 to 30 times the slab thickness.
Joint spacing in feet contraction joints may be tooled into the concrete surface at the time of placement.
Transverse joint spacing should not exceed 125 to 150 of the longitudinal joint spacing.
This tool provides an estimate of the maximum allowable joint spacing based on the slab thickness and the subgrade subbase used two of the variables with the most prominent effect on joint spacing requirements.
For a 100mm slab.
Make sure joints are cut deep enough.
Joint spacing in meters.
It is also important to keep slabs as square as possible.
A 4 thick slab should have joints 1 deep.
Tips for placing concrete expansion joints place joints around 30 times the slab thickness apart.
When using joint groove for contraction joints the joint should be a minimum depth of thickness of the slab.
So for a slab which is 100mm thick the joints should be placed.
Joints should be spaced about 10 feet and a maximum of 15 feet.
Cut joints deep enough cut joints 25 of the depth of the slab.
It is also influenced by the slab dimensions type of concrete and the reinforcing materials being used.
Typically for jointed plain concrete streets the joint spacing should be 24 to 30 times the pavement thickness with a maximum spacing of 15 ft 4 5 m.
Cracks in concrete may occur at the expansion joints due to improper concrete mix or curing.
Maximum joint spacing should be 24 to 36 times the thickness of the slab.
Saw cutting cuts joints as soon as the concrete is hard enough that the edges abutting the cut don t chip from the saw blade.
Keyed joints are not recommended for industrial floors.
Longitudinal joint spacing on two lane and multilane concrete pavements typically is about 10 to 13 ft 3 0 to 4 2 m.
Space joints in feet no more than 2 3 times the slab thickness in inches.
So for a 4 inch thick concrete slab expansion joints should be no more than 8 to 12 feet apart.
They need to be at least a quarter of the thickness of the slab.
A 4 slab should have joints 8 12 feet apart.
Saw cut joints should be done within 4 to 12 hours after the concrete has been finished.
How to cut joints groover tools cut joints in fresh concrete.
If you have a 4 inch slab and multiply it by 24 to 32 you will find that your joints should be placed every 96 to 144 inches or 8 to 12 feet if you have a 5 inch slab and multiply it by 24 to 32 you will find that your joints should be placed every 120 to 180 inches or 10 to 15 feet.
