Study on the creep behavior of PVA-ECC based on fractional-differential rheological model

Abstract

The creep behavior of polyvinyl alcohol (PVA) fiber reinforced engineered cementitious composite (PVA-ECC) was experimentally investigated through long-term uniaxial compressive creep experiments. Eight types of specimens were fabricated and studied with a hydraulic loading equipment with different parameters, including water-to-binder ratio and fiber volume fraction. Based on the rheology theory, a fractional-differential linear model was introduced and successfully simulated the long-term responses of the PVA-ECC. Two existed fractional order Maxwell and integer-order linear models are compared. The experimental results demonstrate that the long-term creep magnitude increase rapidly within the first week and then tends to converge at 90 d under low stress level. The increase in w/b ratio has a negative effect on the specific creep of PVA-ECC. Moreover, PVA fiber can reduce the ultimate specific strain remarkably, and the specimens with 1% and 2% PVA fibers exhibit obviously decline of 29% and 34% in comparison with that of the specimen without PVA fibers. The whole linear viscoelastic behaviors of PVA-ECC can be fitted accurately with the proposed fractional order linear model and the fitting parameters present a clear mechanical significance. Rheological parameters viscosity ηA and fractional order α can reflect the time-depend features and flowing tendency of such multi-phase composites.