Whether due to significant changes in temperature or humidity, due to the shrinkage of concrete or as a result of the application of large loads, concrete slabs can be subject to variations in length and volume. Depending on the extent of these changes, cracks may appear.
There are, however, ways to prevent these random cracks from forming. This is because by introducing joints in the right places, cracking can be prevented.
Discover 3 types of joints that can be made in concrete slabs, each with a specific function.
Shrinkage seals
Shrinkage gaskets have several other names. They are often referred to as control joints, rupture joints, and even contraction joints. All of these terms refer to a type of joint that is used to release internal tensions that can result from the drying of the concrete slab or thermal movements within it.
Because shrinkage joints allow horizontal movement of a concrete slab, they can prevent random uncontrolled cracks from occurring. To be effective, however, they must be arranged in a specific way, i.e. spaced a maximum of 25 times the thickness of the slab according to a grid of no more than 4.5 m between the axes.
Uncoupling joints
Also known as expansion joints, uncoupling joints allow for horizontal and vertical differential movements of parts of a concrete slab or floor that are adjacent to a specific structure.
This type of gasket is therefore particularly useful around the heads of sumps, columns and machinery pedestals. It is also common to find them along the entire depth of the slab, along the foundation walls, which allows it to move without causing cracking. Typically, uncoupling joints are filled with a compressible material that improves the level of insulation, without hindering movement.
Construction joints
Construction joints are normally made on a concrete slab during a prolonged stop in concreting. Normally, they must respect the pattern of the shrinkage or uncoupling joints, in order to preserve the aesthetics that were intended for the work.
Depending on the size of the concrete slab and the use it will be made, steel bars called studs can be inserted into it, in order to allow the transfer of loads. These studs thus allow the absorption of a large part of the shear forces, while allowing horizontal movements. As a result, the concrete can move more freely, eliminating the appearance of random cracks.
If cracks appear in a concrete slab despite the joints
Thanks to these three types of joints, many cracks in concrete slabs can be avoided. However, it could be that despite the addition of joints, a slab will crack, leaving your building vulnerable to moisture and water infiltration.
If you notice cracks in your foundation or concrete slab, don’t take any chances and contact Groupe Fissure Expert immediately. Their team will be able to carry out a thorough inspection of your foundations and offer you quick solutions if the situation requires it.
Need a Crack Repair Expert?
If you notice cracks on your foundation, it is important to act quickly. Fissure Expert offers professional foundation crack injection services throughout Quebec. Call a certified foundation crack contractor for a free estimate. We serve Sherbrooke, Trois-Rivières, Laval and many other cities.