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Using glass fibres to reinforce cement-based materials (CBMs) has great effects on their fresh behaviours. In addition, the impact of water – particularly the average water film thickness (AWFT) – on the fresh properties of CBMs cannot be ignored. However, the combined effects of glass fibre content and AWFT on the fresh characteristics of CBMs are not satisfactorily understood. Therefore, in this study, mortar mixtures with varying fibre/cement (f/c) ratios and water/cement ratios were prepared and subjected to mini V-funnel tests, mini slump flow tests, stone rod adhesion tests, sieve segregation tests and wet packing tests. The AWFTs of the mortar mixes were also determined. The experimental results indicated that the f/c ratio (fibre content) had a noticeable influence on the fresh properties, packing density and AWFT. Modelling analysis demonstrated strong correlations of the workability, flowability, adhesiveness and cohesiveness with the f/c ratio and the AWFT. In other words, both the AWFT and the fibre content collectively serve as governing factors influencing the fresh behaviours of mortars reinforced with glass fibre. [ABSTRACT FROM AUTHOR]

Waste concrete recycled powder (WCRP) occupies up to 30% of crushed old concrete and is hard to be reutilized due to its high porosity and low cementitious reactivity. Traditionally, the WCRP is reused as cement substitution in mortar/concrete production, but this substitution method has certain disadvantages. In this research, a novel substitution method, called the paste substitution method, was applied by replacing part of the cement paste with WCRP; a total of 28 trial mortar mixes containing WCRP added as either paste substitution or cement substitution were made for evaluation and analysis. By comparing the test results, it could be found that the incorporation of WCRP using the paste substitution method can remarkably enhance the compressive strength by at most 38.3%, densify the microstructure, and meanwhile greatly reduce the cement consumption by at most 26.7%. The cementing efficiency factor of WCRP in compressive strength was calculated for the first time, and its value is 0.289. Regression analysis showed that there exists good correlation between the compressive strength and effective water/cementitious materials (W/CM) ratio. [ABSTRACT FROM AUTHOR]

Cementitious paste samples proportioned with blended ordinary Portland cement, pulverised-fuel ash and condensed silica fume (CSF), with different water/cementitious materials ratios and varying superplasticiser (SP) dosages, were produced for packing density and flowability measurements. The results showed that increasing the SP dosage significantly increased the packing density and water film thickness (WFT) of the cementitious paste, and increases in SP dosage and WFT contributed to increasing the flowability of the cementitious paste. At the same SP dosage and WFT, cementitious pastes containing CSF tended to have higher flowability. It is postulated that this is because the finest portion of CSF and water flowed together as a slurry that coated the larger sized particles with a certain slurry film thickness (SFT). Regression analysis of the test data revealed a very good correlation of flowability to SP dosage and SFT. [ABSTRACT FROM AUTHOR]