The air and water-vapour permeance of glass-fibre-reinforced cement* Available to Purchase

Experimental details and results are presented of an investigation of the air and water-vapour permeance of glass-fibre-reinforced cement sheet. Water-vapour permeance decreased with storage in moist conditions, falling to less than half its initial values after 2 years. The air permeance of material stored in dry conditions increased over this period, but low values resulted from exposure to moist environments. Material saturated with water was virtually impermeable to air. After extended periods, the rate of liquid water absorption fell to 2 × 10⁻³ ml m⁻² S⁻¹ (200 mm head) or less. This was compatible with the ‘impermeable’ result of the ISO Impermeability Test.