title: On the mechanical characteristics of a self-setting calcium phosphate cement.
abstract: To perform a mechanical characterization of a self-setting calcium phosphate cement in function of the immersion time in Ringer solution.
  
  
  
  Specimens of self-setting calcium phosphate cement were prepared from pure α-TCP powder. The residual strains developed during hardening stage were monitored using an embedded fiber Bragg grating sensor. Additionally, the evolution of the elastic modulus was obtained for the same time period by conducting low-load indentation tests. Micro-computed tomography as well as microscope-assisted inspections were employed to evaluate the porosity in the specimens. Moreover, diametral compression tests were conducted in wet and dried specimens to characterize the material strength.
  
  
  
  The volume of the estimated porosity and absorbed fluid mass, during the first few minutes of the material's exposure in a wet environment, coincide. The immersion in Ringer solution lead to a noticeable increase in the moduli values. The critical value of stresses obtained from the diametral compression tests were combined with the data from uniaxial compression tests, to suggest a Mohr-Coulomb failure criterion.
  
  
  
  This study presents different techniques to characterize a self-setting calcium phosphate cement and provides experimental data on porosity, mechanical properties and failure. The investigated material possessed an open porosity at its dried state with negligible residual strains and its Young's modulus, obtained from micro-indentation tests, increased with hardening time. The failure loci may be described by a Mohr-Coulomb criterion, characteristic of soil and rock materials.
authors.affiliation: University of Piraeus, GR-18534 Piraeus, Greece; École Polytechnique Fédérale de Lausanne (EPFL), LMAF, STI, CH-1015 Lausanne, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Bimis
authors.affiliation: École Polytechnique Fédérale de Lausanne (EPFL), LMAF, STI, CH-1015 Lausanne, Switzerland.
authors.forename: L P
authors.initials: LP
authors.lastname: Canal
authors.affiliation: University of Piraeus, GR-18534 Piraeus, Greece.
authors.forename: D
authors.initials: D
authors.lastname: Karalekas
authors.affiliation: École Polytechnique Fédérale de Lausanne (EPFL), LMAF, STI, CH-1015 Lausanne, Switzerland. Electronic address: john.botsis@epfl.ch.
authors.forename: J
authors.initials: J
authors.lastname: Botsis
mesh_terms: D001843:Bone Cements / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*; D055119:Elastic Modulus; D008422:Materials Testing; D016062:Porosity; D055114:X-Ray Microtomography
chemical_list: D001843:Bone Cements; D002130:Calcium Phosphates
keywords: Failure criterion; Hardening strains; Low-load indentation; Self-setting; α-TCP