Influence of mechanical activation on the synthesis and hydraulic activity of calcium dialuminate

Calcium dialuminate (CA2, Cdouble bond; length as m-dashCaO, Adouble bond; length as m-dashAl2O3) powders were synthesized from the mechanically activated mixture of calcium hydroxide and aluminium hydroxide. Attrition mill was used for the mechanical activation. A new X-ray phase corresponding to CAH10 was identified after 10 min of attrition milling. The activated mixture was calcined at 1000 °C to obtain CA2. The hydraulic activity of the prepared CA2 was studied using XRD, DTA and compressive strength development. The XRD analysis of CA2 hydrated for different periods indicated the faster conversion of CAH10–C2AH8–C3AH6. In case of mechanically activated CA2, the maximum compressive strength was achieved after 1-day hydration, whereas in conventional CA2 the maximum strength was obtained after 14-day hydration. The faster conversion of hydration phases and rapid early strength development gives an indication of increased hydraulic activity of CA2.