What Causes Concrete to Crack?
There are many factors that can contribute to the cracking of your concrete, and they are almost always caused by external forces applying stress. Understand that concrete is a rigid material that does not accept movement or stress well. When either is introduced, the concrete fractures – sometimes a little, sometimes a lot.
Potential stress inducers include a variety of things. Expanding tree roots can lift the concrete to the point it cracks. Expansion and contraction of the concrete due to temperature change can cause the concrete to move and, over time, ultimately crack. And even more concerning and immediate, is when the concrete is expected to handle the stress of vehicle or even foot traffic, a poorly prepared sub-surface will accelerate the concrete’s failure. If the concrete is on a slight slope, the movement caused by any of the above will cause the concrete to eventually slide down the slope, causing cracks. These are just to name a few.
If you want to repair cracks, the first thing you must do, if you can, is to eliminate the cause of the stress. Many of these causes cannot be corrected or controlled; therefore you may never be able to perform a permanent structural repair. For cracks or damages that can be repaired, the type of material used will impact the quality, durability, and life of the repair.
Because of the constant movement of concrete, any materials that become rigid or brittle should NOT be used for crack repairs. Cementitious materials, as well as epoxies, cure to become brittle and are examples of materials often used, but better suited for other applications. What is needed is a material with high compressive strength, a decent amount of elongation (ability to stretch), high bond strength, and resistance to UV rays. These elements are what make “polymers” the best choice.
FLEXKIT is just that, a polymer-based material with compressive strength as high as 12,000 psi, outstanding adhesion, elongation up to 10%, and resilience of 99.3%, and it is unaffected by the UV rays of the sun. FLEXKIT is the perfect option for making lasting repairs on cracked concrete.
How to Use FLEXKIT to Repair Cracked Concrete
PREP
Clean the crack. We have found the V-Groove grinding wheel to be the best tool for this purpose. Not only will it clean the concrete on both sides of the crack. It will also remove any loose material and leave a clean, sound surface for proper adhesion. Apply the primer to both sides of the crack, making sure not to leave any primer puddled inside the crack. The primer will make its way into the pores of the concrete, and as it cures, it will expand, providing a strong mechanical bond between the primer and the concrete.
APPLY
After the primer becomes tacky like duct tape, mix the FLEXKIT contents as described in the mixing instructions and then apply to the crack with a trowel, forcing the FLEXKIT material into the crack. Make sure you have filled all voids to the point the crack will not accept any more. Smoothen with a trowel.
FINISH
If additional smoothness is desired, a stone grinding wheel mounted on a grinder will make quick work of a final grind and leave you with a very smooth, trip-free surface.
