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

Research output: Contribution to journalArticle

Colleges, School and Institutes


Objectives. 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% radio-opacifier, 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, the paste had an adequate clinical consistency and furthermore these pastes have 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 controls. 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 ratio 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 - 1 Aug 2019


  • tricalcium silicate, rheology, characterisation, water: powder ratio