RECOMMENDATIONS FOR EXECUTION OF CONCRETE FLOOR WILL RECEIVE A HIGH PERFORMANCE COAT (HPC)
This document was prepared by the High Performance Coatings Technical Committee of ANAPRE (National Association of High Performance Coatings and Coatings) and aims to guide specifiers, builders, floor builders and consumers in the best practices for the execution of floors Of concrete that will receive a High Performance Coating – HPC.
For High Performance Coating – HPC it is very important that a floor have a design. A good design defines a series of parameters and specifications that are fundamental to the success of HPC.
In the project, the height of the water table is specified, the sub-base is specified, the correct thickness, the type of concrete, the types of joints, the vapor barrier, the type of distributed and dynamic point request, traffic Type of armor, inclinations, flatness and leveling indexes, agents that will attack the floor, type of curing, etc.
These parameters are essential for defining the thickness of the system, the type of system, the resin used, the finishing details, the type of texture, the types of reinforcements and the treatment of joints etc.
HPC are particularly susceptible to the reverse osmosis effect, also known as rising humidity, where the soil moisture migrates to the surface in the form of vapor and condenses between the coating and the concrete floor forming bubbles of water. This effect depends on several factors, such as high water table, concentration of salts on the surface of the floor, etc. One way to block this rising moisture is to create a vapor barrier with a high-density plastic canvas between the concrete and the subfloor. For this, the ANAPRE recommends that in the execution of all concrete floor must be placed double plastic canvas with at least 200 microns of thickness. The canvas must be intact, without holes or tears, pierced by 30 cm in the splices and installed between the sub-base and the concrete.
The concrete should have a minimum of 25 MPa, but preferably 30 MPa of compressive strength and 3.0 fck of tensile strength. In all cases the concrete should be well vibrated, eliminating the built-in air and increasing the density.
Screen: No restriction
Proposed: No restriction
Steel fibers: attention in the outcrops of fibers in any type of coating
Fibers macros: attention in the outcrop of fibers, especially if it is made of low thickness coating, as paints
Micro fibers: attention in the outcrops of fibers, especially if made of low thickness coating, such as paints
Flatness and Leveling
The Floor Planicity Index must be at least FF 30.
The FL leveling index is not limiting for the use of the HPC as long as it meets the customer’s design or specifications. However, in self-leveling resin systems, the leveling may be a limiter and therefore should be specified. For concrete floors with slope above 2% the self-leveling system can not be specified.
Floors with flatness and leveling rates below the recommended level may be normally coated without damage to adhesion or resistance; However, the deficiencies of leveling and flatness will be emphasized due to the gloss that the floor will have.
Flatness discontinuities may be improved or resolved with HPC provided specific procedures are in place. Coatings alone do not solve problems of flatness.
Surface Finish / Texture
The finish should be smooth without burning or “glazing” the floor The idea of leaving the surface “rough” to “increase adhesion” is false and should be avoided, since any surface before coating should be very well sanded, Blasted to remove the raised cement paste and weak surface materials generated by the curing process, thus ensuring the adhesion of the HPC to a solid and decontaminated base. Rugged textures hinder the cleaning / surface preparation process.
Do not sprinkle water on the surface during finishing, thus avoiding the increase and change of the a / c factor (water / cement), which weakens the surface.
Cure, surface hardener and waterproofing agents
The cure should always be damp, following the design requirements. Chemical cures of any nature should be avoided because they contaminate the surface, make the surface difficult to prepare and fill the pores that must be used to anchor the HPC resin.
Surface hardeners based on silicates, siliconates, fluorsilicates etc. Hamper the penetration of resins; Therefore, should be avoided.
Water repellents based on Silane, Siloxane etc. Are expressly not recommended. They will prevent the penetration of resins on the floor surface, especially if they contain water in their formulations, such as urethane, epoxy and PU systems.
Spraying of metallic or mineral aggregate, high strength layers similar to Korodur and granilites
These techniques, because they are coated, do not contribute to the resistance of the HPC, since the coating is that it will be on the surface suffering the mechanical, chemical and thermal attacks, in addition to hampering the penetration and anchoring of the resin in the substrate because they are denser And closed.
The spray made to lower fibers when the armature is composed of metallic or synthetic fibers does not disturb the adhesion of the coating, since they are more soft and there is much mortar on the surface.
Another problem of these systems is that, because they are richer in salts on the surface, they contribute much with the effect of the reverse osmosis, mentioned in the item Vapor Barrier.