Control Joint Vs Expansion Joint – What’s The Difference?
Construction joints are used to ensure the safety and longevity of concrete structures. Whilst concrete is naturally strong and durable, various factors such as heat and aging, can cause concrete to crack if the necessary joints are not in place. There are many different types of construction joints that are used to build concrete structures, however the two main ones are a control joint vs expansion joint. In order to determine the difference between a control joint vs expansion joint, let’s start by looking at what each of these joints is used for.
What Is A Control Joint?
The main difference between a control joint vs expansion joint is its intended purpose. The purpose of control joints in concrete is to control cracking that’s caused by concrete shrinkage. What does this mean? Well, when concrete is placed and is hardening it tends to shrink or reduce in size as the moisture starts to evaporate. As a result, tensile forces can cause the concrete to crack if it is not strong enough.
These joints prevent cracking by directing the cracks to form in a specific direction so that they don’t compromise the integrity of the structure. The joints are installed at regular intervals along the concrete to protect weaker areas and to prevent acceptable cracks from forming into larger and more damaging cracks.
What Is An Expansion Joint?
As we mentioned previously, there is a big difference in the role of a control joint vs expansion joint. Whilst a control joint is used to control small cracks caused by shrinkage, an expansion joint allows concrete to expand and move as a result of temperature changes, without causing the structure to crack.
Expansion joints are used in both small and large scale building projects and are incorporated in several places along a concrete structure to relieve stress, such as on foundations, walls, roof expansion joints and paving slabs. It’s impossible to prevent concrete from expanding or contracting, however the use of expansion joints allows this to be controlled so as to prevent damage.
So, the main difference between a control joint vs expansion joint is the difference in role when used in construction projects. However, it’s important to emphasise that a control joint vs expansion joint also differs in the following regards:
Placement: Control joints can be created whilst the concrete is being poured or can be cut into the slab once it has been cured. Expansion joints on the other hand must be carefully designed, located and installed as part of an expansion joint system that’s been meticulously planned for the specific construction project at hand.
Size: Another major difference between a control joint vs expansion joint is the size of the project they are applied to. Whilst a control joint is used to prevent small cracks, expansion joints are used to control sizable movements on large structures including bridges, railway tracks and piping systems.
Application: As we’ve mentioned, expansion joints are used to control movement on bridges, railway tracks and piping systems, as well as on the likes of pavements and large buildings. Whilst control joints can also be used in larger building projects, their purpose is to deal with smaller movements and that’s why you’ll often find them used in the likes of slabs, walls and floors.
Having looked at the difference between a control joint vs expansion joint, you can see the importance of selecting the most appropriate and high quality materials for use in construction projects. This doesn’t stop at the structural materials chosen, such as a control joint vs expansion joint. Choosing high quality concrete to support the work of structural elements is vital. Don’t hesitate to get in touch with the team at Al Manaratain today to hear more about our concrete products that are relied upon for civil and commercial projects across Bahrain.