Investigation of the influence of granulometric composition of the aggregate and the content of the binder on the properties of refractory concrete

Abstract

Depending on the additives used, refractory concretes acquire the necessary properties: fire resistance, porosity, heat resistance, maximum application temperature, etc. The influence of the granulometric composition of the mullite aggregate and the content of the binder (cement) on the properties of refractory concrete was evaluated. MLS-62 was used as a filler (the content of the determining component Al 2 O 3 was more than 62%), and Secar 71 high-alumina cement was used as a binder. To test the samples obtained from different granulometric compositions, the mullite aggregate was sieved in fractions (–6+3) mm, –3 mm. In the developed compositions of refractory concrete, these fractions were mixed in different percentages:(–6+3)/(–3). The cement content in the compositions varied by weight: 15%, 20%, 25%. The study was carried out in the factory laboratory, where samples of refractories of all the compositions were made by vibration pressing method. The resulting samples were dried at 110 °C and fired. It was found that after\xa0 drying,\xa0 samples\xa0 with\xa0 a\xa0 cement\xa0 content of 25%\xa0 had\xa0 the highest\xa0 strength\xa0 indicators\xa0 content of 25% was the best result in terms of strength and shrinkage. Studies of the impact of the granulometric composition of the charge on the physical properties of refractory concrete showed that the highest strength indicators were exhibited by samples\xa0 of refractory concrete with a percentage of fractions in the aggregate of 40/60 and 20/80, as well as with the highest amount of cement content in the composition – 25%. After\xa0 firing\xa0 at 800 o C\xa0 and\xa0 1300 o C,\xa0 the strength of the samples decreases. It was shown that the reason of this phenomenon was softening, mainly associated with dehydration of the binder. The refractory concrete obtained with the use of aggregate with a fractional composition of 20/80 and a cement.