Reinforcing mechanisms in asbestos-cement composites

The two main approaches for dealing with the mechanics of asbestos-cement composites are based on composite materials concepts (rule of mixtures) and fracture mechanics, Microstructural characterization of the composite has usually been carried out in conjunction with these studies, to determine the numerical parameters required for the modelling, such as the aspect ratio, and to resolve the pull-out and fracture processes during failure. The results of these microstructural studies wi II be reviewed first, since they provide the background required for the modelling of the processes which control the mechanical performance of the hardened composite, 

SEM characterization of the fractured surface of asbestos-cement composites was reported by Akers and Garrett [4,11] and Mai [12], It was shown that in the actual composite, a considerable portion of the fibres was in the form of bundles 

2 Prediction of mechanical properties - composite materials approach 

The composite materials approach, based on the rule of mixtures (reviewed in Section 4.3) has been applied by various investigators to account for the modulus of elasticity, tensile strength and flexural strength of asbestos-cement composites. 

Allen [7] considered the modulus of elasticity in terms of the rule of mixtures (see Equation 4.26)  

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