Apatite formation on calcined kaolin-white Portland cement geopolymer

In this study, calcined kaolin-white Portland cement geopolymer was investigated for use as biomaterial. Sodium hydroxide and sodium silicate were used as activators. In vitro test was performed with simulated body fluid (SBF) for bioactivity characterization. The formation of hydroxyapatite bio-layer on the 28-day soaked samples surface was tested using SEM, EDS and XRD analyses. The results showed that the morphology of hydroxyapatite was affected by the source material composition, alkali concentration and curing temperature. The calcined kaolin-white Portland cement geopolymer with relatively high compressive strength could be fabricated for use as biomaterial. The mix with 50% white Portland cement and 50% calcined kaolin had 28-day compressive strength of 59.0 MPa and the hydroxyapatite bio-layer on the 28-day soaked sample surface was clearly evident.