Control Joints vs. Expansion Joints: What You Need to Know | Kaloutas

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Control Joints vs. Expansion Joints: What You Need to Know

Facility room under maintenance. Control Joints vs. Expansion Joints: What You Need to Know

When installing con­crete floor­ing, your con­trac­tors will like­ly sug­gest that you include joints, with con­trol joints and expan­sion joints being the most com­mon. It’s impor­tant for you to under­stand both kinds so you are pre­pared to fol­low your floor­ing contractor’s sug­ges­tions for your facil­i­ty. Learn­ing the dif­fer­ence between the two will also help you main­tain your expan­sion and con­trol joints in con­crete, keep­ing your facil­i­ty safe and functional. 

Con­ve­nient­ly, you no longer have to won­der, What is the dif­fer­ence between con­trol joint and expan­sion joint con­crete?” This guide has all of the rel­e­vant infor­ma­tion you need to know. 

Con­trol Joints vs. Expan­sion Joints

What Are Con­trol Joints: A Summary

A con­trol joint is the most com­mon type of joint you will see in con­crete floor­ing. These are designed to con­trol crack­ing as the floor cures. Installing and main­tain­ing con­crete con­trol joints helps pre­vent ran­dom cracks from form­ing in the floor over time, even after reg­u­lar use, shifts in the earth, tem­per­a­ture changes, and more.

What Are Expan­sion Joints: A Summary

Expan­sion joints are cut all the way through the depth of your con­crete slab. These joints are placed there to allow the con­crete to expand and con­tract with­out dam­ag­ing the floor­ing or its struc­tur­al integrity.

A Clos­er Look at Con­trol Joints

Con­trol joints in con­crete are some­times called con­trac­tion joints. These joints are cut into the con­crete while it is still fair­ly fresh. Most of the time, it will be cut with­in about six to 18 hours of a con­crete pour. While expan­sion joints are cut all the way through, con­trol joints only go about a quar­ter of the way through a slab.

These joints are designed to con­trol the crack­ing direc­tion as the con­crete slab shrinks over time. The goal is for most of the crack­ing to occur with­in these con­trol joints instead of the con­crete — this extends the dura­bil­i­ty of the floor while improv­ing its appearance.

Because you want any cracks or move­ment to occur in the joints, they are placed at the part of the floor with the high­est ten­sile stress. This includes spots in long walls or slabs, as well as abrupt changes in a cross-section.

A Clos­er Look at Expan­sion Joints

To bet­ter under­stand expan­sion joints, remem­ber that con­crete will form to the ground’s topog­ra­phy as it dries. But cer­tain parts of the con­crete will shrink more, caus­ing stress and pulling on oth­er areas of the slab. The expan­sion and con­trac­tion also occur with changes in tem­per­a­tures. Heavy loads can also cause extra stress on the floor, lead­ing to cracks.

As men­tioned, expan­sion joints are cut through­out the entire slab. They are then filled with a com­press­ible mate­r­i­al or filler. 

Includ­ing expan­sion joints in your con­crete lets the mate­r­i­al expand and con­tract with­out cre­at­ing ran­dom cracks. Essen­tial­ly, an expan­sion joint will iso­late var­i­ous parts of your slab, let­ting the entire slab move with­out caus­ing undue strain on any area.

The way that your floor­ing expert cuts expan­sion joints depends on the weath­er. In hot­ter weath­er, they typ­i­cal­ly use groov­ing tools while the ini­tial con­crete is still wet. But in cool­er areas, pro­fes­sion­als can cut them using a saw after some hard­en­ing has occurred.

To cal­cu­late the max­i­mum dis­tance between expan­sion joints, take the con­crete width in inch­es. Change the units to feet and mul­ti­ply them by two or three. If your con­crete slab is four inch­es thick, you need joints no more than eight to 12 feet apart.

You will find expan­sion joints in near­ly any type of con­crete floor­ing struc­ture. This includes side­walks, bridges, pave­ment, slabs, ships, build­ings, pip­ing sys­tems, rail­road tracks, and more.

Sum­ma­riz­ing the Differences

Based on the above infor­ma­tion, you’ll notice that con­trol and expan­sion joints have dif­fer­ent pur­pos­es and sizes. They are also installed at dif­fer­ent times. 

Con­trol joints are specif­i­cal­ly designed to pre­vent cracks from shrink­age as the slab dries, while expan­sion joints are there to pre­vent future cracks due to expan­sion and con­trac­tion. An expan­sion joint is cut through the entire con­crete slab. On the oth­er hand, con­trol joints only go about a quar­ter of the way through it.

Sum­ma­riz­ing the Similarities

Both types of joints are designed to pre­vent your con­crete floor­ing from form­ing cracks, although they do so in slight­ly dif­fer­ent ways and at slight­ly dif­fer­ent times. Both joint types are also notice­able if you look at the floor close­ly. As such, most con­trac­tors will do their best to either hide the joints (such as under walls) or make them dis­creet. If an area needs a lot of expan­sion joints, they may even be turned into an aes­thet­i­cal­ly pleas­ing pat­tern, such as a checkerboard. 

Oth­er Types of Joints

Keep in mind that expan­sion and con­trol joints are far from the only types you will see in con­crete floor­ing. There are also iso­la­tion joints and cold joints. Iso­la­tion joints sep­a­rate con­crete slabs from oth­er types of sur­faces, such as pipes, struc­tur­al beams, or walls. They are nec­es­sary because oth­er sur­faces move at dif­fer­ent rates than con­crete slabs. Cold joints refer to the seam cre­at­ed when you pour one slab and then pro­ceed to pour anoth­er next to it. 

The Impor­tance of Main­tain­ing Your Joints

Now that you under­stand the dif­fer­ence between con­trol joint and expan­sion joint con­crete, it’s time to con­sid­er main­te­nance. No mat­ter the type of joint you have in your con­crete, it will require reg­u­lar main­te­nance. Main­tain­ing con­crete con­trol joints is just as impor­tant as prop­er­ly fill­ing them with flex­i­ble joint mate­r­i­al dur­ing the instal­la­tion process. Make sure your cho­sen con­trac­tor uses the appro­pri­ate flex­i­ble joint mate­r­i­al dur­ing repairs as well.

A few poten­tial issues come with joints. If you don’t care for them prop­er­ly, debris and oth­er items can enter the joints. This could poten­tial­ly dam­age them or hurt their functionality. 

The oth­er issue with joints is that the edges can start spalling and break­ing away. This is espe­cial­ly com­mon in high-traf­fic areas.

Edges that spall or break away are a seri­ous trip­ping haz­ard, putting your team at a safe­ty risk. On top of that, it will cause the con­crete to dete­ri­o­rate. It can even dam­age your fork­lifts by increas­ing wear on them.

Joints Can Become Too Dam­aged for Sim­ple Repairs

If you notice any of these issues but don’t address them imme­di­ate­ly, you can run into even larg­er prob­lems. If the joint reach­es a cer­tain width, you won’t be able to fill it with flex­i­ble mate­r­i­al, as this would not be strong enough to sup­port a forklift.

In this case, you may need to chip out the entire sec­tion and rebuild it with mor­tar. Only then would you be able to install new, small­er, flex­i­ble joint fill. Because this process is more involved, it takes longer and costs more than reg­u­lar joint repairs. 

What Hap­pens Dur­ing Expan­sion Joint Repair?

As men­tioned, it is cru­cial to repair and main­tain expan­sion and con­trol joints. The process of repair­ing expan­sion joints typ­i­cal­ly starts with grind­ing uneven sur­faces to make them even. Then, the repair tech­ni­cians will clear debris. They will then place joint filler to make a lev­el sur­face. From there, the tech­ni­cians can cut a new joint into the repaired floor. Final­ly, they fill it with the flex­i­ble joint filler. 

Your floor­ing repair team can also replace or repair the epoxy coat­ing on sur­round­ing parts of the floor. 

Find a Reli­able Joint Main­te­nance and Repair Team

Kaloutas is proud to be New England’s pre­mier provider for con­trol joint repairs and main­te­nance. By spe­cial­iz­ing in repairs and main­te­nance, we can focus on per­fect­ing the best tech­niques and diag­nos­tics for your joints. Our exper­tise ensures dam­aged joints are addressed and don’t inter­fere with your busi­ness operations.

Let the experts at Kaloutas inspect, repair, and main­tain your facil­i­ty’s con­trol joints for stur­dier, safer floors. Con­tact us and get a quote today.

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