title: Effect of different mixing methods on the physical properties of Portland cement.
abstract: 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.
  
  
  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 atP<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.
authors.affiliation: DDS, MSc, Professor, Dental and Periodontal Research Center, Dental Faculty, Tabriz University (Medical Sciences), Tabriz, Iran.
authors.forename: Shahriar
authors.initials: S
authors.lastname: Shahi
authors.affiliation: DDS, MSc, Assistant Professor, Department of Endodontics, Dental and Periodontal Research Center, Dental Faculty, Tabriz University (Medical Sciences), Tabriz, Iran.
authors.forename: Negin
authors.initials: N
authors.lastname: Ghasemi
authors.affiliation: DDS, MSc, Professor, Dental and Periodontal Research Center, Dental Faculty, Tabriz University (Medical Sciences), Tabriz, Iran.
authors.forename: Saeed
authors.initials: S
authors.lastname: Rahimi
authors.affiliation: DDS, MSc, Associate Professor, Department of Endodontics, Dental Faculty, Tabriz University (Medical Sciences), Tabriz, Iran.
authors.forename: Hamidreza
authors.initials: H
authors.lastname: Yavari
authors.affiliation: DDS, MSc, Associate Professor, Department of Endodontics, Dental Faculty, Tabriz University (Medical Sciences), Tabriz, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Samiei
authors.affiliation: DDS, MSc, Assistant Professor, Department of Endodontics, Dental Faculty, Tabriz University (Medical Sciences), Tabriz, Iran.
authors.forename: Farnaz
authors.initials: F
authors.lastname: Jafari