Effect of dispersants on the hydrate morphologies of spinel-containing calcium aluminate cement and on the properties of refractory castables

Abstract This research studied the effects of several dispersants on the morphologies of cement hydrates and properties of refractory castables. The results showed that the cement hydrate morphologies were closely related to the types of dispersants used. With naphthalene sulfonate formaldehyde condensate (FDN) and sodium tripolyphosphate (STPP) as dispersants, the cement hydrate of C 3 AH 6 obtained anomalistic shapes, and the AH 3 particles showed a diameter of not more than 1 μm. When propionic acid (PA) was added, C 3 AH 6 formed inerratic cubical grains, whereas AH 3 changed from particles to long column agglomerates; the ratio of the long radius increased with increasing PA concentrations. The addition of PA as dispersant generated CaCH 3 CH 2 CO 2 + , which resulted in a decrease in Ca 2+ concentration. Also, the relatively higher apparent porosity satisfied the space requirement for the growth of C 3 AH 6 , eventually resulting in larger inerratic cubical grains. The H + hydrolyzed from PA accelerated the growth on the (100) and (110) crystal planes of AH 3 ; thus, gibbsite stretched along the c -axis. The maximum values of CCS and CMOR for refractory castables prepared with PA as dispersant were 5.6 MPa and 46.6 MPa, respectively, which were higher than those for refractory castables with FDN and STPP. The observed excellent performance in strength might be related to the bridging effect resulting from the long-column AH 3 .