Concretos refratários utilizados na indústria do cimento - análise comparativa de desempenho em função do tipo de ligante e da forma de aplicação

Abstract

Refractory material has a strategic importance in the productive chain of industry, as it provides essential materials for the operation of equipment. In Brazil, after steel, the cement industry presents the greatest demand for refractories. This segment is constantly requiring improved refractory performance, lower cost and fast application. Refractory concrete due to its ability to meet these requirements, together with its application versatility, has gained market compared to traditional bricks. This study focused on the development of a concrete capable of meeting requirements present in the clinker production process. In the cement industry the concrete resistance to thermal shock damage, alkalis infiltration and erosion are some of the pre-requisites in order to be considered a high performance castable. In this context, this study proposes to make a correlation between these properties of refractory concrete when changing the conventional calcium aluminate cement (CAC) binder for Colloidal Silica (CS) and application method, from vibration to shotcrete. The results of thermal shock damage revealed that systems with CAC are less resistant to this wear mechanism when compared to the SC system, and projectable systems resist thermal shock better when compared to vibrated systems. The results of the alkalis attack resistance test (RAA) showed that all concretes CAC and SC, vibrated or projectable, were classified as Grade 1 (excellent RAA), confirming that silico-aluminous concrete has high resistance to alkali attack. The SC binder system presented lower resistance to damage by erosion when compared to the CAC binder. For both mixtures with SC and with CAC, greater erosive wear using the projectable system was observed when compared to the vibrated system. Although concrete containing colloidal silica is shown in this study to be a promising substitute for refractory concrete bound with CAC, the findings of this study make it evident that there is no a superior technology to another, that no material will combine all the necessary properties to meet at the same time all mechanisms of wear, equipment or application. For this reason, the success of each technology depends on its correct specification, considering all the variables and operating conditions attached to the application site