Experimental investigation of the effects of dispersed nanoalumina additive on plastic viscosity and yield stress values of cement-based grouts with fly ash

The effects of nanoalumina (n-Al2O3) additions at various proportions by mass (0.0, 0.3, 0.6, 0.9, 1.2 and 1.5%) on plastic viscosity and yield stress values of cement-based grout replacement with fly ash at different contents (0% for control purposes, 5, 10, 15, 20, 25 and 30%) were experimentally studied in this work. To minimize nanoalumina precipitation in free water and to provide homogeneous dispersion in water by removing these adhering nanopowders from each other, the ultrasonication method was applied. Test results showed that shear thickening (dilatant) behaviour was observed in all grout samples. The flowability of cement-based grouts containing fly ash considerably increases with the amount of nanoalumina added to the grout samples. The addition of nanoalumina and fly ash together in the grout mixes caused a considerable decrease in the yield stress value of these mixtures. Moreover, using all the experimental data obtained, an artificial neural network was developed to predict the plastic viscosity and yield stress values. The developed model was able to predict plastic viscosity with an average error rate of −0.17% and yield stress with an average error rate of 0.24%.