Evaluation of the thermal shock resistance of aluminate-silicate refractory castables. Effect of the thermal treatment

摘要

In this work, the thermal shock response of commercial fireclay refractory castable with low alumina content was analyzed with the aim of evaluating the feasibility to be used as replacement of silicate-aluminate refractory bricks in a non-severe process. The study was performed in laboratory scale, with procedures especially designed based on the available standards, employing 2 commercial castables supplied by different manufacturers. Specimens cured for 24 h, 48 h and 7 days (for comparison with samples of civil concrete) were evaluated; some specimens were also thermally treated at 900 degrees C. As-received materials were characterized through granulometric analysis by sieving and X-ray diffraction. The specimens were mechanically tested in flexion and compression; moreover, the density, the porosity and the dynamic Young's modulus of the samples were measured. The thermal shock test was performed by air cooling; after each cycle, the dynamic Young's modulus was determined. At the end of the fifth cycle, the residual mechanical strength in flexion and compression was also determined. The results showed that the castable with finer granulometry and better mechanical performance before the thermal shock (castable A), was the most suitable to be used without a previous thermal treatment. (C) 2019 SECV. Published by Elsevier Espana, S.L.U.