This study sought to prepare biphasic mixtures by adding tricalcium aluminate (Ca₃Al₂O₆) into dicalcium silicate (Ca₂SiO₄) and to evaluate the effect of Ca₃Al₂O₆ on setting properties and biocompatibility of the Ca₂SiO₄/Ca₃Al₂O₆ mixtures as compared to pure Ca₂SiO₄. The results indicated that the addition of Ca₃Al₂O₆ into Ca₂SiO₄ reduced the setting time and improved the compressive strength. Furthermore, Ca₂SiO₄/Ca₃Al₂O₆ mixtures were bioactive and biocompatible, and had a stimulatory effect on the L929 cell growth when the content of Ca₃Al₂O₆ was below 10%. Therefore, the mixtures with 10% Ca₃Al₂O₆ produced the best compromise between setting and in vitro biological properties.