It can be frustrating to see a damaged polished concrete floor. Whether the polished concrete floor is in a retail store, warehouse, building lobby, home garage, it doesn’t matter; even hardened and densified polished concrete can crack, chip, and stain. Here are three suggestions for repairing polished concrete floors:
Stains and Scratches
Even though they are merely superficial, certain users of polished concrete floors may wish to repair stains, scratches, and wear due to foot traffic. For example, this may be necessary for hospitals and medical facilities, restaurants, grocery stores, and other users that have heightened concerns. This might include worries over bacteria, viruses, mold spores, dust, and even allergens that can be trapped in even shallow scratches.
Repairing shallow damage is a matter of grinding the floor to smooth out the surface or remove the stains and wear, then re-polishing it. More specifically, a single head auto scrubber or rotary floor scrubber can be fitted with grinding tools embedded with industrial diamonds to remove a thin surface layer.
Because industrial diamonds are the hardest substance on Earth, metal bond diamond abrasive and resin diamond abrasive tools are highly efficient at grinding polished concrete. Moreover, industrial diamonds have high thermal conductivity, which means that heat is transferred away from the surface of the grinding pad, thereby reducing glaze and wear.
Once the surface is smooth and even, it can be re-polished. If necessary, a color-matched densifier or pore filler can be applied to harden the concrete surface. The surface is polished with tools of increasingly finer grit until the desired level of polish is obtained. The polished surface may then be treated with sealant.
Cracks may open up for many reasons that are unrelated to the care of the floor. That is, cracks may appear in a polished concrete floor even without being damaged by an impact. Concrete is strong in its capacity for compression but it has very low tensile strength. Any stresses that tend to pull the concrete will cause cracks to form. For example:
- Thermal stress from heating and cooling can cause concrete to crack. Thermal stress can even occur in indoor concrete floors due to temperature fluctuations caused by sunlight, water pipes, steam pipes, and HVAC ducts.
- Settling of the support for the polished concrete floor can cause cracking. If the concrete floor is supported by the foundation, the concrete may crack as the foundation settles. If the polished concrete floor is integral with the foundation, soil subsidence and compaction may cause the polished concrete floor to settle unevenly and cracks may result.
- Dry shrinkage of concrete occurs over time as the moisture content of the concrete drops. The amount of shrinkage depends on the amount of water, and the ratio of cement to aggregate, in the concrete. The typical concrete mix is 60-75% aggregate, 15-20% water, and 10-15% cement, which means the concrete will lose as much as 15-20% of its mass as it dries. Thus, concrete has been observed to shrink by 3% or more. Pouring smaller slabs separated with seams can reduce the risk of cracking of slabs by redirecting the stresses of pulling the seams apart. However, the seams will widen over time, eventually necessitating repair.
Patching polished concrete floors takes a few steps. The first step to patching polished concrete floors is to clean the crack of debris and dust. Once clean, the crack can be filled.
The patching material of choice is polyurethane strengthened with microfibers. Concrete dust and dyes can be added to polyurethane so it blends with the existing concrete floor in both appearance and texture. Grinding and polishing of the patch can occur after the patch cures so that the patch blends with the surrounding polished concrete floor.
Patching polished concrete floors that are chipped is essentially the same as patching polished concrete floors that are cracked. The chipped area is cleaned and color matching polyurethane patching material is applied over a few coats, with the patch allowed to dry between coats. Once the patch cures, grinding and polishing can be performed.
Repairing polished concrete, whether it is scratched, cracked, or chipped, merely requires patching the damage. When you’re ready to invest in the safety of your floors, rely on Eco Guard to transform your business.