Effect of different mixing methods on the physical properties of Portland cement

BACKGROUND The Portland cement is hydrophilic cement; as a result, the powder-to-liquid ratio affects the properties of the final mix. In addition, the mixing technique affects hydration. The aim of this study was to evaluate the effect of different mixing techniques (conventional, amalgamator and ultrasonic) on some selective physical properties of Portland cement. MATERIAL AND METHODS The physical properties to be evaluated were determined using the ISO 6786:2001 specification. One hundred sixty two samples of Portland cement were prepared for three mixing techniques for each physical property (each 6 samples). Data were analyzed using descriptive statistics, one-way ANOVA and post hoc Tukey tests. Statistical significance was set at P<0.05. RESULTS The mixing technique had no significant effect on the compressive strength, film thickness and flow of Portland cement (P>0.05). Dimensional changes (shrinkage), solubility and pH increased significantly by amalgamator and ultrasonic mixing techniques (P<0.05). The ultrasonic technique significantly decreased working time, and the amalgamator and ultrasonic techniques significantly decreased the setting time (P<0.05). CONCLUSIONS The mixing technique exerted no significant effect on the flow, film thickness and compressive strength of Portland cement samples. Key words:Physical properties, Portland cement, mixing methods.