Analytical calculation for structures in reinforced and pre-stressed concrete can only be carried out according to the criteria laid down in the standards EN1991-1-2, EN1993-1-2 and EN1994-1-2. For passive protection systems using soft plaster or plasterboard panels, it is possible to do the calculations with either advanced or simplified methods, provided that the values used for the thermal properties (λ) of the materials (density, specific heat, conductibility coefficient) have been arrived at using the prescribed experimental procedure. It should be noted that this option is not available for reactive protection systems (intumescent paints) as the thickness calculation can only be done using experimental assessment procedures.
Assessment using comparison tables makes it possible to work out the thickness of the protective coating on the basis of the type of material used, the fire-resistance rating and the construction features of the elements to be protected. If the comparison table method is to be used, it is important to check that the elements to be protected correspond to or have improved construction features compared to those in the tables.
The said tables can only be used for the purpose of fire-resistance rating if the manufacturer states, on the basis of their own testing experience, that the product guarantees the performance claimed for it, accepting liability for this statement. The manufacturer must also state that the product demonstrates the necessary adhesion and cohesion for the time period corresponding to the required fire-resistance rating. This statement must be accompanied by instructions for applying the coatings or for installation. This method does not apply to reactive paints given their intrinsic fire-protection properties.
Assessment of protective systems for reinforced and pre-stressed concrete structures through experimental testing involves laboratory testing carried out in compliance with the provisions of the document EN 13501-1. For fire-proofing coatings this document refers to the standard EN 13381-3-2002: “Test methods for determining the contribution to the fire resistance of structural members. Part. 3: Applied Protection To Concrete Members”. Laboratory testing of reactive coatings requires a long series of tests in which the various reinforced and pre-stressed concrete elements are subject to controlled fire to check the effectiveness of the protective system applied, in terms of duration, adhesion and a number of other parameters. By interpolating the results of all these tests it is possible to arrive at an assessment of the thickness of the protective coating of Amotherm Concrete WB to produce the required fire-resistance ratings, taking into account the various values of the concrete cover and different critical collapse temperatures.
For masonry and concrete flooring, the reference standards for testing purposes are UNI EN 1365-2 of 2002 and UNI 1363-1 of 2012. The field of application is as set out in the test report issued by the accredited laboratory.