CARDIFRC: MANUFACTURE AND CONSTITUTIVE BEHAVIOUR

摘要

This paper will first describe the important steps necessary for the manufacture of the high performance fibre reinforced cementitious composite developed at Cardiff University. These steps have been patented, and the class of materials produced were registered under the trademark CARDIFRC~(~R). The two most important steps are the maximisation of the dry density through optimisation and the even and random distribution of short steel fibres up to a volume fraction of 8%. Two lengths of fibre were used, 6 and 13mm, the diameter in each case being 0.15 mm. The even distribution of fibres was confirmed by sectioning and image analysis, as well as by the non-destructive technique of computerised tomography. The paper also introduces a micromechanical model for describing the constitutive behaviour of CARDIFRC~(~R). This model predicts the tensile strength, the compressive strength and the toughness of the material as function of the mix and fibre parameters. Most importantly, the model allowed workability of the mix (without fibres) to be included as a technological constraint. This was achieved by first relating the workability to the fracture toughness of the brittle matrix, i.e. by expressing the latter as a function of the mix variables (volume fraction of quartz sand, water to binder ratio, superplasticizer to water ratio, maximum size of quartz sand) for a given workability.