What are the reasons for the peeling and damage of epoxy floor coating?

What are the reasons for the peeling and damage of epoxy floor coating?

Epoxy flooring generally has a service life of 8 to 15 years, but many parking garages often experience damage to the epoxy coating of the flooring after 2 to 3 years, or even shorter. The peeling problems related to the base layer of epoxy coatings mainly include the following situations:

Coating peeling and damage:

There are two main situations of coating large-scale peeling and damage:

① The interface between the epoxy resin layer and the concrete base layer is damaged, manifested by the detachment of the epoxy coating, while the concrete base layer is normal and undamaged, with a large area appearing. The direct cause is insufficient interfacial adhesion;

② The epoxy coating is tightly combined with the mortar on the surface of the concrete base, and the failure surface appears inside the concrete base, located on the mortar plane of the concrete base. This type of damage usually occurs on a large scale, and the direct cause is the insufficient tensile strength of the concrete. The peeling of different coating layers of epoxy coating also occurs, mainly due to insufficient adhesion between different coatings, which generally occurs locally and is not common in large areas.

Bulging and cracking of epoxy coating:

The coating has local protrusions, mainly manifested as protrusions with diameters of 2-5mm and 30-50mm to varying degrees. The main reason is that the base layer is not dry enough, gas accumulates under the paint film, the coating surface absorbs moisture and protrudes, or impurities are not cleaned up during the curing of the paint film. Cracks appear in the coating, manifested as shrinkage cracking of the coating film and tensile cracking of the coating due to cracks in the base layer. The two situations of delamination damage are caused by insufficient strength, one is insufficient interfacial bonding strength, and the other is insufficient tensile strength of the shallow surface layer of the concrete base. During the usage phase, there are two main factors that contribute to the internal stress generated by the interface and shallow surface of the concrete base: one is the internal stress generated by vehicle loads, and the other is the temperature stress generated by temperature changes.

Reasons for epoxy coating peeling

The vehicle load will not cause the peeling and damage of the epoxy coating in the parking garage alone; The main reason for the delamination and damage of the epoxy coating is the uncoordinated deformation between the epoxy coating and the concrete base caused by changes in external temperature. When the bonding strength of the bonding interface is less than the tensile strength of concrete, the failure surface will appear at the bonding interface; When the bonding force at the interface is greater than the tensile strength of concrete, the shallow surface of the concrete base is damaged. In practical applications, the internal forces generated by vehicle loads and temperature changes can be combined and considered. The curing shrinkage of epoxy coating can reach 0.2% to 2%, and its shrinkage stress cannot be ignored, which may completely cause coating peeling and damage. When dividing the concrete base into small pieces through expansion joints, it is necessary to consider the adverse effects of shear stress at the interface between the epoxy coating and the concrete base.