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 (GB 0109686.6), and the class of materials so produced are 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%. A combination of two fibre lengths (6 and 13 mm) of diameter 0.15 mm has been used to increase both the tensile strength and toughness. The even distribution of fibres has been confirmed by sectioning and image analysis of cylinders, prisms and thin strips, as well as by the nondestructive technique of computerised tomography. The paper will next describe the constitutive behaviour of CARDIFRC~(~R) using micromechanics. The pre-peak strain hardening and the post-peak tension softening response are quantified in terms of the matrix and fibre parameters. Most importantly, the workability of the matrix (without fibres) has been included as a technological constraint in this description. This is achieved by first relating the workability of the brittle matrix to its fracture toughness, i.e. by relating the latter to the matrix variables (volume fraction of quartz sand, water to binder ratio, superplasticizer to water ratio, maximum size of quartz sand) for a given workability.
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