Effect of the quality of microsilica on the flow properties of cement slurry and characteristics of low-cement refractory concrete on a chamotte filler

The effect of impurity content in different grades of microsilica (MS) on the physicomechanical characteristics of a low-cement refractory concrete based on a chamotte filler is considered. The high content of impurities in MS degrades the flow properties of cement slurry and the respective concrete slurry. It is shown that as ambient temperature grows to 30°C, the impurities in MS increase the cement slurry thickness and impede the placement of refractory concrete in summer period. If low-quality MS is used in concrete, an increased crack formation is observed under the cyclic high-temperature effect. __________ Translated from Novye Ogneupory, No. 5, pp. 41–46, May, 2007.