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 C3AH6 obtained anomalistic shapes, and the AH3 particles showed a diameter of not more than 1μm. When propionic acid (PA) was added, C3AH6 formed inerratic cubical grains, whereas AH3 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 CaCH3CH2CO2+, which resulted in a decrease in Ca2+ concentration. Also, the relatively higher apparent porosity satisfied the space requirement for the growth of C3AH6, eventually resulting in larger inerratic cubical grains. The H+ hydrolyzed from PA accelerated the growth on the (100) and (110) crystal planes of AH3; thus, gibbsite stretched along the c-axis. The maximum values of CCS and CMOR for refractory castables prepared with PA as dispersant were 5.6MPa and 46.6MPa, 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 AH3.