ABSTRACT
The early theoretical studies on FRC in the 1950s and 1960s (e.g., Refs 1 and 2) dealt primarily with the behaviour of steel fibre reinforced concrete (SFRC). Since then, SFRC has continued to attract more research than other fibre concretes, and, with the exception of asbestos, steel remains the most commonly-used fibre for concrete reinforcement. World production of steel fibres in 1984 was estimated to be about 20 000 tonnes,3 rising to an estimated production of 60 000 tonnes in 1988,4 (compared with about 2.7×106 tonnes of asbestos fibres5). At a typical addition of 50kg/m3, this yields about 1.2×106 cubic meters of SFRC annually. Steel fibres greatly increase the toughness of cements and concretes: they are used primarily for crack control, to replace the secondary reinforcement often used for that purpose in flat slabs, pavements, and tunnel linings, as well as in various repair applications. The increase in toughness can prevent, or at least minimize, cracking due to changes in temperature or relative humidity, and can increase the resistance to dynamic loading (due to fatigue, impact, or blasting). The range of property improvement that can be achieved by the addition of steel fibres has been demonstrated by Shah and Rangan,6 as shown in Fig. 7.1. It may be seen that improvements in strength are modest; the chief effect is the large increase in toughness.
