Age effect on the characteristics of fibre/cement interfacial properties

The experimental findings of an investigation on the age development of interfacial properties of polyethylene fibers in a cementitious matrix are reported. It was found that the interfacial bond strength matures much faster, in less than 7 days, in comparison with bulk property development, which typically takes 14–28 days. A parallel ESEM study of the microstructure development in the interfacial transition zone supported the fact that the rapid early age saturation of the interfacial adhesive bond strength is associated with the growth of a CH rim around the fibre periphery. The formation of the CH layer appears to be completed much earlier than the hydration process of the bulk material. The slip-dependent friction after initial debonding was found to develop with age up to 28 days, gradually converting from a slip-weakening to a slip-hardening behaviour. These findings should be useful in interpreting early age fibre-reinforced cementitious composite properties.

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