STEEL FIBER REINFORCEMENT IN CEMENT BOUND BASES

This paper presents innovative research aimed at preventing the propag ation of cracks in a cement bound roadbase through a bituminous surfac ing, termed reflective cracking, by using steel fibre reinforcement, T he performance of cement bound materials (CBMs) has been investigated with reference to the influence of 1% steel fibre reinforcement (by vo lume) upon direct and indirect tensile strength, compressive strength, elastic stiffness, load versus deformation characteristics, and post- cracking behaviour. In the case of a steel fibre reinforced CBM materi al, cracking of the CBM has been found to start at a stress level sign ificantly lower than the ultimate strength of the composite material. These cracks have a very small width and a high load transfer, which h as been shown to minimize differential vertical movement across the cr ack faces. This particular characteristic of steel fibre reinforced (S FR) CBM base is expected to be of critical importance in limiting refl ective cracking, which has been shown to be influenced by the magnitud e of the differential vertical movement at cracks, This may allow a re duction in the thickness of bituminous surfacing which, otherwise, wou ld be required to withstand the high tensile strains developed under t rafficking.