RECOMMENDATION FOR THE USE OF ROBERTS FLOORING ADHESIVES OVER SEALED CONCETE SURFACESIntroduction
Concrete is sealed for a number of reasons, but probably the three main reasons are as follows:
Concrete curing membranes
When concrete is laid it is necessary for it to remain wet during its curing process to gain maxim strength. In order to keep the water in the concrete a number of techniques may be used including
the use of curing membranes. These membranes are usually sprayed onto the surface and form
an impermeable layer.Decorative finishes
Concrete may be finished with paint, coatings etc to provide an inexpensive attractive appearance which in some cases can be hard wearing for factory floors etc.Concrete sealers
Concrete is sometimes sealed to prevent liquids entering from above that may contaminate the concrete causing odour problems e.g. Nursing homes, Industrial process etc. Generally no Roberts water based adhesive should be used directly onto a sealed floor. Polyurethane and Epoxy adhesive may be used on sealed concrete floors in some instances where a compatibility test has been carried out and the adhesive has been deemed to be compatible, giving acceptable bond strength.Water Based adhesives
Water based adhesives, when used in the wet stick mode, cannot be used to adhere resilient flooring products e.g. Vinyl, rubber, linoleum, cork etc. to a sealed concrete surface because the water (moisture) in the adhesive becomes entrapped between two impermeable layers. Water based adhesives need to loose their water content in order to form the adhesive film. If water based adhesive
is used in this situation, the adhesive will not be able to dry and would remain permanently wet thus leading to failure of the installation. Water based adhesives when used in the dry stick mode, e.g. pressure sensitive adhesives, can be used to adhere resilient sheet flooring to sealed concrete surfaces in some instances where there is no compatibility problems e.g. The sealed surface contains waxes
or other release agents that may inhibit the formation of an acceptable bond. In order for a water based adhesive to be used over a sealed concrete surface a Cementitious underlayment such as
Roberts 20 Self Level should be used in conjunction with the appropriate primer/binder, and laid at least 3mm thick to provide enough volume to absorb the necessary quantity of moisture from the adhesive.Polyurethane and Epoxy Adhesives
Polyurethane and Epoxy Adhesives cure by chemical means that is there is a chemical reaction between part A and part B if it is a two part system or by reaction with moisture in the air if it is a one component system. Two part systems cam be used in some instances where resilient flooring is to be installed directly over concrete surfaces, where the loss of moisture is not necessary. In this situation the compatibility and ability of the adhesive to bond to the sealed surface is the main issue. Roberts’ 555 Polyurethane two part adhesives can be used in these circumstances but only if a test has been carried out to determine the suitability of the adhesive with the substrate. One component Polyurethane adhesives such as RLA 1017 are not recommended to adhere resilient sheet flooring to sealed surfaces as the ability of moisture from the substrate to reach the adhesive is greatly diminished, resulting in extremely slow curing rates and probable installation failure.Adhesion of non-resilient flooring to sealed concrete surfaces
Textile flooring products, where the backing is permeable and allows moisture to penetrate, can
be adhered to sealed surfaces using water based adhesives as long as the compatibility of
the adhesive and surface sealer has been tested. It is preferable that a cementitious underlayment
is used in this situation.Warrantys
RLA Polymers will only warrant the use of Roberts Adhesives over sealed concrete floors if the above guidelines have been adhered to and where there is any ambiguity about a specific installation,
RLA Polymers should be consulted and written advice should be obtained.Issued: September 2004
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