Researches have been devoted to new types of binder, aiming the replacement of the calcium aluminate cement (CAC) in refractory castables formulation. Although it is one of the most employed binders, CAC shows some drawbacks, mainly on the reduction of the system's refractoriness when microsilica is present. Recent publications suggest silica sol as a suitable alternative; nevertheless its use must be adapted to refractory castables. The purpose of this work was to optimize the use of silica sol and evaluate the microsilica effect on systems containing this sort of binder. Drying behavior, mechanical strength, porosity, permeability, refractoriness under load and creep were evaluated as a function of curing time. The results showed that the addition of microsilica to silica sol bonded castables can increase the mechanical strength without affecting the drying behavior.
refractory castables; silica sol; microsilica
