The measurement and significance of green sheet properties for the properties of hardened fibre cement

It is common practice for manufacturers of cellulose fibre cement to measure thickness, density and water content of freshly made fibre cement as manufacturing control measures. The thickness of the green fibre cement accurately reflects the thickness in the hardened state and is therefore an instantaneous direct control. However, world standards for fibre cement typically call for fibre cement to be made to a particular strength and although density and water content may be predictive of strength in general, they do not reflect the orientation of the fibres and their contribution to the directional strength of finished product. The purpose of this paper is to introduce two tests of the properties of green fibre cement (green sheet tensile test and green sheet modulus of elasticity) and to show how the properties of the green sheets relate to those of the hardened product. It will be seen that both of these green sheet properties relate directly to the strength of the hardened sheet.