For the success of a project that involves the drafting of resinous formulations, two important factors must first be evaluated:

the SUPPORT with its characteristics

the WORKING CONDITIONS to which the coating will have to operate

The pavement that are encountered most frequently are cement-based and can have as a basis:

• Floor tiles
• Asphalt
• Metal
• Wood
• Old resins

The characteristics of the pavement that help to define the final behavior of a resin flooring are:

• intrinsic qualities such as age, mechanical strength, elastic modulus, cohesion;
• compatibility with the coating;
• thermal expansion coefficient;
• internal structure (presence of voids, capillarity, etc.);
• state of the surface;
• planarity;
• humidity at the time of installation and in service;
• surface temperature.

The intrinsic qualities of the surface are fundamental characteristics to be taken into consideration. It should stay in mind that the resinous coating, not self-supporting, must be able to rely on a sufficiently rigid support, free of cracks (especially in the evolution phase) and stable.

The minimum quality characteristics of a concrete surface, suitable for the application of resinous coatings, are:

• tear strength> 1.5 MPa;
• compressive strength at 28 days => 25 MPa;
• absence of operating humidity and rising damp.

The coating, depending on the thickness, behaves like a load distribution plate, reporting these values ​​in a reduced and distributed form at the adhesion interface.

This graph shows the distribution on the support of a point load weighing on the coating: note that as the thickness of the coating increases, the surface of the support on which the load is distributed increases and therefore the load per unit area decreases accordingly. By distributing the load, the tensile forces that interact at the lining / support interface decrease, thus decreasing the risk of tearing.

The cohesion of the substrate must not be less than 1.5 MPa in order to ensure good adhesion between the two layers (substrate / resin floor).

It should stay in mind that, due to the alkalinity of the cementitious matrix supports, some types of resin can suffer saponification problems, both during application and hardening.

Old substrates, on the other hand, can be polluted by chemical products, even in depth, which can be followed by an attack on the substrate or coating laid, in the short or long term, which could lead to degradation of the substrate and detachment of the coating. .

In practice, in the choice of the covering or, if possible, in the design phase the compatibility characteristics between the substrate and the covering must be taken into account in order to obtain the expected performance from the flooring.

The degree of humidity present on the substrate may derive from an unsuitable environmental condition, from the water contained in the concrete (unseasoned substrates) or from the capillary rising damp from the substrate.

The latter derived largely from the support / ground contact and can be generated both during application and operation.

In the presence of humidity, when highly waterproof resin floors are applied, a physical osmotic phenomenon can be triggered at the coating / substrate interface which involves swelling of the resinous coating (blistering).

The degree of humidity of the substrate can be checked using a carbide hygrometer. The humidity of the substrate must be less than 4%.

There are hygrometers on the market that measure by contact using specific ultrasound probes (TRAMEX).

Carbide hygrometer

                                                     Ultrasound hygrometer

          On site it is also possible to carry out a practical test that allows you to evaluate, in a simple and representative way, if the substrate is in the correct humidity conditions for laying the flooring:

in an area with the possibility of heat exchange by solar radiation (near windows, for example), a polyethylene sheet with a surface area of ​​1 m2 is spread;

in glue the edges with tape;

and check for internal condensation phenomena.

SIVIT, in his production range, has two specific primers for the management of rising dump.

ECOFONDO: three-component epoxy primer for wet substrates for transpiring cycles.

Learn more by consulting the technical data sheet

https://sivit.it/wp-content/uploads/2020/10/SCHEDA-TECNICA-E-02Fondi-03-Ecofondo.pdf

ECOFONDO PLUS: three-component epoxy primer for wet substrates, to obtain the vapor barrier effect for reverse hydrostatic pressure values ​​of 250 kPa.

Find out more by consulting the technical data sheet.

https://sivit.it/wp-content/uploads/2020/10/SCHEDA-TECNICA-E-02Fondi-04-EcofondoPlus.pdf

CONDITIONS OF OPERATION

For a correct floor covering design, the main factors to consider are:

• Type of traffic with definition of loads
• Possible chemical aggressions (aggressive type, nature and contact temperature).
• Thermal resistance required
• Destination of the premises:

• antistaticity
• food contact
• reaction to fire
• non-slip
• …

The evaluation form summarizes and collects everything that needs to be carefully evaluated, in order to propose an adequate solution to the Customer.