Hydraulic properties of the tricalcium phosphate-dicalcium phosphate mixture

Abstract

A new combination of α-Ca3(PO4)2 (TCP) and CaHPO4·2 H2O (DCPD), each of which alone had a low or no hydraulicity, was proposed and investigated on its hydraulic properties. This combination showed a high hydraulicity probably due to the complementarity that the hydrolysis of TCP to octacalcium phosphate (OCP) was accelerated by the coexistence of DCPD and vice versa. Setting times were 9-30 min and reaction products were OCP only in the range of 1.20 to 1.47 in the mixing molar ratio Ca/P. Hardened bodies soaked in 0.9% NaCl solution at 37°C for 1 day had a porosity of 49±3% and a wet compressive strength of 14-19 MPa, in comparison with 52±4% and 6-11 MPa for a Ca4(PO4)2O-DCPD combination and 66±2% and ca. 2 MPa for a DCPD-CaCO3 combination.