Types of Joints Used to Prevent Cracks on Concrete

There is no doubt about the fact that concrete is one of the toughest construction materials .The extra toughness associated with concrete often makes it the material of choice for a wide variety of construction-related projects and applications. However, even with this toughness there is no foolproof way to prevent mechanical failure (often referred as cracking) on a concrete surface. That having been established, it is important to point out that the use of joints is one of the best-known ways to prevent mechanical failure on concrete surfaces. This article discusses the various types of joints used to prevent cracks, hence eliminating the need for repairing cracks in concrete surfaces.

Isolation Joints-Isolation joints are also referred as expansion joints in some quarters. An isolation joint is often placed in situations where there is need for the total separation of adjoining concrete and the floor. This is done so as to allow for the independent movement of these joints without causing any form of damage.

Expansion or isolation joints will often be made of a cork-like material that is largely made of asphalt. Just like their name suggests, expansion joints are designed to allow for the expansion and subsequent contraction of concrete surfaces. A properly designed expansion joint will help to reduce the need for repairing cracks in concrete surfaces for a long time to come.

Construction Joints-A construction joint will often be placed in the slab on which concrete –related activities for the day were last concluded. Construction joints are used to prevent cracking of concrete surfaces that are still under construction when there is an interruption in construction activities for one reason or the other. Common reasons for such interruptions include harsh weather conditions.

It is important to point out that if an interruption in construction activities lasts for long enough, a cold joint may appear on the surface of the concrete slab. Should this ever be the case, a construction joint should be installed irrespective of the previously desired joint layout.

Control Joints-Control joints are also quite effective in eliminating the need for repairing cracks in concrete surfaces. Control joints are also commonly referred to as contraction joints and will often be placed on the possible lines of weakness where mechanical failure of concrete is most likely to occur.
A control joint is used to create a straight line of weakness in the crack-prone area and the minimum depth required for a control joint should be a equal to a quarter of the thickness of the concrete slab in question.
Concrete control joints are often formed using jointers or groovers. The jointer or groover is designed with cutting edges or bits that are used to form narrow groves on concrete slabs in accordance with the thickness of each slab.

Saw Joints-Saw joints are often defined as control joints that have been sawed in to be as straight as possible. Saw joints are often installed in clean lines of a depth equal to a quarter of the slab thickness. In order for saw joints to be useful in eliminating the need for repairing cracks in concrete surfaces sawing has to be done in good time before the concrete begins to dry and take shape.

These are the primary types of joints used to prevent cracks and eliminate the need for repairing cracks in concrete surfaces. For more information on concrete joints and mechanical damage on concrete surfaces, get in touch with the experts at Road Surgeons PTY LTD.

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