Some experimental evaluations on the rheological and non-Newtonian fluidity properties of fly ash added cement-based grout prepared by addition of nano zinc oxide (n-ZnO)

In this study, the plastic viscosity and yield stress of cement-based grouts containing n-ZnO nanoparticle added fly ash have been experimentally investigated. The fly ash ratios of the prepared grouts are 5%, 10%, 15%, 20%, 25%, and 30% by mass. The n-ZnO nanoparticles ratios in each fly ash concentration are 0.3%, 0.6%, 0.9%, 1.2%, and 1.5%. In this study, w/b ratio was selected as 1.0 because of that observing the effects of higher w/b ratios on the rheological properties of grout mixes. Ultrasonication method was applied to minimize n-ZnO precipitation in free water and to provide homogeneous dispersion in water by removing these adhering nano powders from each other. Test results showed that as the dilatant (shear-thickening) behavior was observed in all grout samples prepared for this study, modified Bingham analytical model was used to describe the rheological properties and flow behavior of the grout samples prepared for this study. n-ZnO appears to have a significant effect on regulating the amount of water required for cement-based grouts. The substitution of fly ash together with n-ZnO in grout mixtures causes the plastic viscosity values of the samples to decrease. The exponential increase is observed for the yield stress of the grout mixtures with respect to the increase in the n-ZnO additive ratio. Moreover, the increase in the fly ash amount in all n-ZnO additives causes the yield stress values of the mixtures to decrease. In addition to all, the developed artificial neural network model can predict the plastic viscosity and yield stress values of cement-based grouts containing n-ZnO nanoparticle added fly ash with average error rates of -0.52% and -0.31%, respectively.