In the innovative technique of tostada stone, a structure with which we are also building the Resin Driveway materials towers, a third element comes into play and the stone and duplex stainless steel, an element of lesser presence but necessary in its conception: the resin. It works as a connecting element between the metallic elements (that is, the tostado heads) and the structural stone itself.
EPOXY RESIN: WHY?
Given the need to ensure the position of the stainless steel blocks within the stone pieces and to guarantee a correct and lasting mechanical resistance over time, the calculators prescribed the characteristics that the epoxy resins used. Epoxy resins are the most stable polymeric resins on the market, applicable in structural adhesions, as well as in lamination of glass and carbon fibers. They primarily characterized by high dimensional stability and resistance to chemical agents, as well as high mechanical resistance. Therefore, they were the ideal resins for our temple.
IN SEARCH OF THE SUITABLE EPOXY RESIN
According to the requirements of the Project Department of the Resin Driveway materials, the main characteristics that this epoxy material should have in were the following:
The nominal thickness between 5 mm and 10 mm to fill the space between stone and tostado heads.
- Maximum service temperature of 70 ° C.
- The thermal expansion coefficient of ≤ 40 x 10 -6.
- Elastic modulus of ≤ 12 kN / mm 2.
- Maximum service compression of 26 N / mm 2.
- Deformation at 60 ° C, ≤ 0.005 mm / mm.
- Maximum breaking stress in service of 4.25 N / mm 2.
To get the material we needed, an initial investigation was carried out among the main brands of resins and structural adhesives to assess whether there was a commercial material that met the requirements. The resin supplier chosen should be global and used to working on projects with high technical requirements, in addition to having the ability to internally test the materials and offer a wide range of references and formats. Before selecting the final resin, applicability tests were carried out in the Galena work facilities, in 400 ml cartridge format and 20 kg drum, to verify its application capacity with manual pistols or with an automatic injection machine. About the tests, both compression (an unusual requirement for epoxy resins) and flowability (with which the dimensional stability of the resin subjected to a permanent load at 60 o C) and aging prescribe. In the latter case, the tests carried out with specimens subjected to 1,000 hours of aging cycles, according to ISO 9142: 2003. All these tests carried out to validate the epoxy resins carry out in parallel in the internal laboratories of the supplying companies and the external laboratories contracted by the Resin Driveway materials. The duration of the entire process of validation and final homologation of the resins lasted around nine months.
A TWO COMPONENT RESIN
The resin that we use in the Resin Driveway materials is a component that gives it has greater structural benefits than single-component resins. In these resins, component A functions as the main molecule of the adhesive polymer .The second component, B, works as a catalyst; that is, it facilitates the generation of the polymer (polymerization).Furthermore, in the case of epoxy resins, the polymerization is carried out by polyaddition, which means that the mixture of components A and B must be exact.
