The Effect of Paste Concentration on ...

Calcium phosphate cements show many advantages comparing to other calcium phosphate-based materials. The objective of this study was to investigate the influence of paste concentration controlled by liquid-to-powder ratio on compressive strength, setting characteristics and phase composition of α-TCP based calcium phosphate cements. The powder phase consisted of α-TCP, DCPA, CaCO3 and hydroxyapatite which were mixed with aqueous solutions of 3 wt% H3PO4 at three different liquid-to-powder ratios (0.35, 0.40 and 0.45 mL/g). The cements were characterized in terms of setting time, compressive strength and porosity. Also XRD and SEM techniques were employed to evaluate the phase composition and surface morphology of the cements. The results revealed similar phase composition for all samples before and after soaking in Ringers solution. Reduction in liquid-to-powder ratio led to increment of compressive strength of CPCs from about 15 MPa for the cement with L/P ratio of 0.45 to about 30 MPa for L/R ratio of 0.35 after 7 days soaking in Ringers solution. Also by reducing the L/P ratio from 0.45 to 0.35, initial and final setting times of the CPCs decreased 3 and 5 minutes respectively. A highly microporous structure was also obtained for cements with different liquid-to-powder ratios.