Lightened fire-resistant soft plasters are usually formulated on a base of plaster/cement to which inert ingredients of various types have been added, such as vermiculite, polystyrene and cellulose, to lighten the specific weight and increase the mass and insulating power compared to ordinary plaster. Each type of plaster has its own specific heat insulating co-efficient (λ). The thickness of plaster to be applied to obtain the desired fire-resistance rating is calculated according to the structure to which it is to be applied, the critical temperature required and, by applying the insulation co-efficient, it is possible to calculate the insulating thickness that must be used. Since these plasters are not only used on concrete but also metal surfaces, their cohesion and adherence are of critical importance. AMONN has joined forces with GRACE, the world leader in the production of lightened fire-resistant plasters, and recommends the various Monokote solutions for passive fire protection.

In passive fire protection differentiation is made between products designed to slow heat propagation in order to limit the damage to buildings and other structures (resistance), and products designed to reduce the combustion capacity of normally inflammable materials (reaction). For non-combustible structural elements the focus is on raising their resistance to fire for a determinate period of time. For combustible construction elements, such as wood, in addition to their fire resistance, the requirement is that the wood should not contribute to triggering fire and feeding its propagation. The main factor for the resistance requirement is the length of time, while the fire reaction requirement is not linked to any time factor, the material must comply with the combustibility classes provided for by the regulations

• Two defence mechanisms are used for protective paint systems, the first being intumescence while the second involves increasing the fire-proof properties of the materials.
  • The word intumescence is derived from the Latin word intumescens “swelling”, and that is exactly how this defence mechanism works in paints that, when they are subjected to heat or flame, swell up and create a carbonaceous layer that acts as a protective barrier. The thermal insulation power of the foam generated by the chemical and physical process triggered by the rise in temperature increases the fire-resistance of the structure to which it is applied.
  • A paint is defined as fire-proofing if it possesses properties that notably reduce the combustion capacity of the wood surface to which it is applied. Fire-proofing paints use chemical reactions intended to extinguish the flames or to limit their propagation. Fire-proofing paint therefore, alters the reaction to fire of the materials to which it is applied.
  FOTO: Column with intumescence and wood after being subjected to Class 1