Determination of stochastic matrix cracking in brittle matrix composites

Inorganic Phosphate cement (IPC) is a cementitious material developed at the "Vrije Universiteit Brussel" which can be reinforced with E-glass fibres. In order to improve its application in civil engineering constructions like wall and roof panels, the constitutive behaviour of this IPC composite should be fully understood and accurately modelled. In compression, the behaviour of IPC composite is nearly linear elastic up to failure. Unfortunately, in tension the behaviour of IPC composite is completely different. Since matrix cracks initiate and propagate at very low stress levels, the stress-strain relation is linear only in a very small region. Using a stochastic cracking theory, the averaged matrix crack distance can be calculated as a function of the applied tensile stress. This theory is experimentally verified using a stereomicroscope equipped with a video camera and image acquisition board. Both unidirectional and 2D-random oriented fibre reinforcement is used.