Improving the dynamic splitting properties of engineered cementitious composites using hybrid synthetic polymer and recycled steel fibres

To improve the dynamic mechanical behaviour and make full use of recycled waste tyres, this study investigates the feasibleness of partial replacement of polyvinyl alcohol (PVA) fibres with recycled tyre steel (RTS) fibres in engineered cementitious composites (ECC). A series of laboratory tests were carried out to evaluate the work-ability, elastic modulus and uniaxial tensile behaviour, as well as the quasi-static and dynamic splitting tensile behaviour of ECC containing PVA and RTS fibres. The experimental results indicate that the replacement of 0.25% PVA fibres with RTS fibres results in a 0.85 MPa drop in tensile strength, while a nearly one-tenth increase in first-crack strength appears as the stronger RTS fibre-to-matrix bonding is effective in controlling the initiation of the first crack. Under dynamic loading, the mono PVA fibre reinforced ECC gradually loses the specimen integrity due to the rupture of PVA fibres at higher strain rates, while the bridging effect of RTS fibres contributes to maintaining the specimen integrity even at the highest measured strain rates of 7.3-7.5 s-1. Moreover, the replacement of 0.5% RTS fibres can lead to up to 15.54% and 27.38% increase in dynamic splitting strength and dissipation energy, respectively, relative to that with 2.0% PVA fibres. In addition, the evolution of dynamic increase factor with strain rate is modelled by theoretical equations considering the content and length-to -diameter ratio of fibres, the predictions of which match well with the experimental results.

Automated summary

This study investigates the feasibility of partially replacing polyvinyl alcohol (PVA) fibers with recycled tire steel (RTS) fibers in engineered cementitious composites (ECC) to improve their dynamic mechanical behavior and make use of recycled waste tires. Laboratory tests were conducted to evaluate the workability, elastic modulus, uniaxial tensile behavior, and dynamic splitting tensile behavior of ECC containing PVA and RTS fibers. The results show that replacing 0.25% PVA fibers with RTS fibers decreases the tensile strength by 0.85 MPa but significantly increases the first-crack strength. RTS fibers also contribute to maintaining specimen integrity under dynamic loading, resulting in increased dynamic splitting strength and dissipation energy compared to using PVA fibers. The predictions of the dynamic increase factor with strain rate match well with the experimental results.