Investigation of the effect of the water to powder ratio on hydraulic cement properties

A. Koutroulis, H. Batchelor, S. A. Kuehne, P. R. Cooper, J. Camilleri

Research output: Contribution to journalArticle

3 Citations (Scopus)


Objective: The use of rheological properties to determine the optimal water: powder ratio of tricalcium silicate-based prototype materials incorporating alternative radiopacifiers and fillers. Determination of how the proportion of water incorporated affected the physicochemical behaviour of the materials. Methods: Endodontic cements replaced with 30% radiopacifier, and additions of calcium phosphate and micro-silica were tested. The unmodified cements were mixed with a 0.35 water: powder ratio which served as control. At this water: powder ratio, unmodified Portland cement without any addition had an adequate consistency and furthermore it has been well characterized. Assessment of material rheological properties enabled adjustment of the water: powder ratio in each material to provide comparable viscosity values to those of the pure cement. The flowability, phase analysis and calcium release were measured for both viscosity-matched and the standard 0.35 water: powder ratio blends. The prototype materials with the adjusted water: powder ratios were also characterized by scanning electron microscopy, energy-dispersive spectroscopy and evaluated for radio-opacity. Results: The use of the 0.35 water: powder ratio is not appropriate when changing the radiopacifier and incorporating additives. Zirconium oxide did not vary the water: powder ratio but tantalum oxide and calcium tungstate resulted in an increase and decrease in water demand respectively. Using the standard 0.35 ratio when the mixture had a low water demand resulted in higher flowability values and calcium release in solution. Micro-silica and calcium phosphate altered the hydration of the materials. All materials were adequately radiopaque. Significance: Rheological assessment is an easy reproducible way to determine the water: powder ratios of materials with varying amounts of additives and radiopacifiers during development. Modifications to the water: powder ratio affects material properties.

Original languageEnglish
Pages (from-to)1146-1154
Number of pages9
JournalDental Materials
Issue number8
Early online date29 May 2019
Publication statusPublished - 31 Aug 2019
Externally publishedYes


  • characterisation
  • rheology
  • tricalcium silicate
  • water to powder ratio

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    Koutroulis, A., Batchelor, H., Kuehne, S. A., Cooper, P. R., & Camilleri, J. (2019). Investigation of the effect of the water to powder ratio on hydraulic cement properties. Dental Materials, 35(8), 1146-1154.