Glassfibre-reinforced gypsum (GRG) combines the non-combustibility of gypsum plaster with the reinforcing strength of glass fibres. Products contain typically 5% of the standard E-glass fibres, which considerably improve impact as well as fire resistance.
Commercial GRG products are available as standard panels, encasement systems for the fire protection of steel and decorative wall panels. As with all gypsum products, standard GRG should not be used in damp conditions or at temperatures regularly over 50°C.
GLASSFIBRE-REINFORCED GYPSUM BOARDS
The standard boards, available in a range of thicknesses from 6–12.5 mm, are manufactured with a glassfibrereinforced gypsum core and glassfibre tissue immediately below the gypsum faces. The material is suitable for a wide range of applications including wall linings, ceilings and protected external positions such as roof soffits. The material can be easily cut on site and fixed with nails or screws; in addition, owing to the effect of
the glassfibre reinforcement, it can be curved to fit, for example, barrel-vault ceilings. The minimum radius of curvature depends on the board thickness. The material has a smooth off-white finish; joints should be taped
before finishing board plaster is applied.
For the fire protection of steelwork, high-performance, Class 0 board thicknesses of 15, 20, 25 and 30 mm are available. Depending on the steel section factor, A/V (surface area per unit length/volume per unit length), with double layers and staggered joints, up to 120 minutes’ fire resistance may be achieved (Fig. 11.7).With specialist steel fixings to the structural columns, up to 180 minutes’ fire protection is achieved with glassfibre-reinforced gypsum boards.
Decorative glassfibre-reinforced gypsum boards and components
Decorative boards manufactured with a range of motifs may be used as dado or wall panels, false ceilings or organic forms . Dabs are used to fix panels to the substrate allowing for adjustment to a flush joint. Finally panels may be painted.
Ceiling tiles manufactured from GRG are available in a wide range of designs, including plain, textured, patterned, open- or closed-cell surface and with square, tapered or bevelled edges. The standard size is usually
600 X 600 mm, although some manufacturers produce a wide range of units. GRG has good fire-resistant properties; it is non-combustible to BS 476 Part 4: 1970, Class 1 surface spread of flame to BS 476 Part 6: 1989, up to Class 0 to Building Regulations Section E15 and Euroclass A2-s1,d0 (no significant contribution to the fire load, no evolution of smoke or flaming
droplets). It does not emit noxious fumes in fire. Acoustic tiles with enhanced sound absorption and attenuation properties are normally part of the standard range, which may also include Imperial sizes for
refurbishment work.
A wide range of small decorative components is manufactured in GRG, including cornices, coving, ceiling centres, corbels, columns, arches and niches.