As you know, joints are cut in new concrete floors to control cracking. As a fresh concrete slab hardens, it reduces in volume and shrinks. When this shrinkage is restrained by the slab’s contact with the sub-grade, adjoining structures, or reinforcement within the concrete, tensile stresses develop within the slab. While a concrete floor is very strong in compression, its tensile strength is relatively low. The result of this internal tensile stress is cracking of the concrete.

The most widely used method to control cracking in concrete slabs is to place joints in the slab at specific locations that create weakened areas where the concrete can crack in a straight line. This produces an aesthetically pleasing appearance since the inevitable crack takes place under the joint, below the finished concrete surface.

Unfilled joints are especially vulnerable to damage and tend to “spall” under the impact from hard wheeled traffic. Damaged joints result in a bumpy floor surface that can cause:

  • Unnecessary wear and tear on material handling equipment such as tow motors, scissor lifts, and carts
  • Equipment driver fatigue
  • Loss of product
  • Chemical contamination of the slab and sub-base when oils/chemicals are spilled and seep into open joints

The Solution

The size and cost of floor joint repairs can be kept to a minimum if the damage is detected and repaired at an early stage. Regular inspections should be made to check that any existing joint filler is doing its job to protect and maintain joint edges. If damage has been allowed to progress beyond the scope of re-filling joints, it will be necessary to reconstruct the joint itself. This is done with our heavy duty, fast curing repair mortars that are specifically intended for industrial floor use. Both processes shown below have been specifically developed for use in operational industrial facilities and warehouses with no need to shut down or remove inventory.

Joint Repair Method A

Using Joint Repair Method A*, edge spalling of mildly damaged joints can be corrected to produce a smooth, seamless floor.



Hard wheeled traffic impacts against unfilled or unprotected joint edges, causing spalling.

Any existing, damaged joint filler is removed, joints are cleaned, and fast-curing joint filler material is installed. Warehouse traffic experiences smooth transition across joint.

Floor joint repair method A

  1. Surface view of joint edges spall under heavy traffic. If even minor spalling is ignored, the problem will worsen quickly.
  2. Joints are recut to produce smooth, stable edges.
  3. Joint filler is shaved flush to create a smooth transition for wheeled traffic.
  4. Cross-section of crack in the concrete. 

* This method can also be used to repair random cracks.

Joint Repair Method B

If more serious damage has occurred, joints will need to be fully reconstructed by using Joint Repair Method B.



Wide, spalled joints are experiencing major damage due to continued hard-wheeled impact.

All damaged concrete is removed and replaced with durable concrete repair mortar, followed by re-cutting and filling of joints. Floor becomes smooth and impact-free.

Floor joint repair method B

  1. A wide, severely spalled joint.
  2. All damaged concrete is removed, and edges are squared off.
  3. Cross-section view: Tough and durable Euclid Chemical repair mortars replace the damaged concrete. 
  4. Cross-section view: The existing joint is ‘honoured’ by re-cutting through the repair material, and the new joint is filled with Euclid Chemical semi-rigid joint filler.
  5. Cross-section view: A roughened repair base ensures good bond between the repair mortar and concrete. 
  6. Surface view: The repair is finished smooth to ensure an impact-free transition across the joint.

Article contributed by Jennifer Crisman, Director of Marketing Services at Euclid Chemical.

Concrete Specialist

For over a century, The Euclid Chemical Company has served the global building market as a worldwide quality supplier of specialty products for the concrete and masonry construction industry. Tremco CPG is proud to supply Euclid Chemical’s wide range of specialty products for new construction or restoration projects across the Asia Pacific region.

Our expert team are on hand to provide you with complete solutions for your next concrete project, do get in touch with the team.

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