Mullite based castables are usually applied for lining steel industries processing ladles due to their superior working performance. However, the presence of aluminate cement and SiO2 can deteriorate their hot properties by the formation of eutectics and low melting point phases, which motivates the search for alternatives biding systems. In this paper, the three main binders for refractory castables (aluminate cement, hydratable alumina and colloidal silica) were added to different compositions and their green and hot properties were compared, aiming to define which one presents better performance. The results indicated the colloidal silica as a promising substitute to the aluminate cement as it favors the drying process, provides excellent hot properties, higher refractoriness and generates low residual liquid phase after sintering, when compared to a high alumina composition.
colloidal silica; binding system; mullite; refractory concrete
