Experimental Study and Modelling of Fresh Behaviours of Basalt Fibre-Reinforced Mortar Based on Average Water Film Thickness and Fibre Factor.

Though previous studies have indicated that the fresh behaviours of plain mortar/concrete are mainly governed by the average water film thickness (AWFT), whether the concept of AWFT is also applicable to fibrous mortar/concrete still needs to be explored. Furthermore, for fibrous mortar/concrete, it is obvious that the fibres added also have certain effects on the fresh behaviours. In two previous studies on basalt fibre-reinforced mortar (BFRM), the integral effects of the AWFT and fibre dosage as well as the integral effects of the AWFT and fibre length were individually investigated. In this study, a fibre factor (FF) defined as the fibre volume multiplied by the fibre aspect ratio was employed and 24 extra mortar groups were tested. A total of 68 mortar groups were applied in numerical analysis. The results of the regression analysis yielded good correlations of the workability, fluidity, cohesiveness, and adhesiveness of BFRM with the AWFT and FF, suggesting that the AWFT and FF are together the governing parameters controlling the fresh behaviours of BFRM. Hence, the AWFT and FF may be used to develop a model for the fresh properties of BFRM.

Effect of Silica Fume on the Rheological Properties of Cement Paste with Ultra-Low Water Binder Ratio.

The effect of silica fume on the rheological properties of a cement-silica fume-high range water reducer-water mixture with ultra-low water binder ratio (CSHWM) was studied. The results indicate that the W/B ratio and silica fume content have different effects on the rheological parameters, including the yield stress, plastic viscosity, and hysteresis loop area. The shear-thickening influence of CSHWM decreased with the increased silica fume content. When the silica fume content increased from 0% to 35%, the mixture with W/B ratio of 0.19 and 0.23 changed from a dilatant fluid to a Newtonian fluid, and then to a pseudoplastic fluid. When the silica fume content was less than 15%, the yield stress was close to 0. With the increase of silica fume content, the yield stress increased rapidly. The plastic viscosity and hysteresis loop area decreased slightly with the addition of a small amount of silica fume, but increased significantly with the continuous increase of silica fume. Compared with the Bingham and modified Bingham models, the Herschel-Buckley model is more applicable for this CSHWM.