Cellular glass and polyurea: a good combination?

logo_smallPolyurea is an elastomer with a very large tensile strength (40Mpa) and elongation (500%). On top of that, it can absorb a lot of kinetic energy without damaging the underground, like illustrated in the following paper. The last property is the consequence of a glass transition of the polyurea under a high deformation rate. This (reversible) glass transition takes a lot of energy, which returns as heat after impact without remaining deformation.

polyurea formulaThe weakness of cellular glass are its dusty surface, the lower tensile / bending strength and a rather weak surface. By applying polyurea, the dusty and weak surface are completely  eliminated, while the large tensile strength / elongation eliminate the immidiate failure consequence of a crack in the cellular glass due to bending or tension. In fact, a board cellular glass, coated on all sides with polyurea behaves as an extremely robust light board. Standard polyurea is combustible with EUROCLASS F and removes an important strong point of cellular glass.

reaction to fireBut with the addition of some flame retarders,  Epaflex has a polyurea with  Reaction to fire classification B s2 d0 today available with  10 MPa tensile strength and 280% elongation. This means no risk for flashover and no (dangerous) droplets during a fire, with limited smoke generation while the cellular glass mechanical properties are largely improved.

polyureaIndeed, on the condition of a suitable Reaction to Fire classification, polyurea and cellular glass may be a good combination. A straightforward application could be a cellular glass flat roof, built with large cellular glass boards (less joints) where the water proofing membrane is replaced by polyurea.

autoPolyurea coated cellular glass has indeed a huge bending strength in relation to its weight like shown in this picture. Uncoated celllular glass never takes a weight of about 500 kg in these circumstances.

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