Recent advances in refractories - aluminate binders and calcium aluminate bonded high-performance monolithic castables

References indicate that the first ‘refractory concretes’ can be traced as far back as 1856, when Deville (1856) prepared a refractory crucible using alumina aggregate and alumina cement. Calcium aluminate cement (CAC) and a method for its industrial production were patented by Lafarge in 1908 (Soc. J&A. Pavin de Lafarge, 1908). The first industrial production of calcium aluminate cement was by Lafarge in 1913. It was not until the 1920s that the heat resistant properties of calcium aluminates were exploited (Arnould, 1922). The first references to a commercial refractory concrete can be found around 1922-24, when work in both France and the USA led to the development of Bauxite/Cement Fondu® based compositions. During the early days of refractory concretes, the main aggregates available for use were calcined clays and crushed fired refractory bricks. The concretes were crudely made and even more crudely applied. Mixing was commonly done by hand in a mortar box or wheelbarrow, while casting, slap-towelling, and hand-forming were the most common forms of installation, although some gunning was also done. During the 1930s there was great expansion in the use of refractory and refractory insulating concretes in a variety of applications. By the outbreak of World War II refractory concrete was well established in many industries that used furnaces and ovens (Robson, 1978). By the 1960s, castables based on highpurity CAC and high-purity aggregates were common (Kerneos, 1969). These were relatively simple compositions comprising refractory aggregates with cement contents typically greater than 15%, but were becoming increasingly sophisticated in terms of particle size management and adaptation to specific conditions and installation techniques. More products were being manufactured as proprietary mixes in-house rather than as onsite field mixes. Despite the tremendous advantages of ease of placing and monolithic construction, these conventional or regular concretes did not always possess the required installed characteristics for a specific application. The 1970s saw the introduction of lowcement castables (LCCs) with the landmark patent by Prost and Pauilliac (1969). In the LCC system, the CAC cement is part of a complex binder system that can be viewed as an interdependent triangle. In this triangle the Recent advances in refractories — aluminate binders and calcium aluminate bonded high-performance monolithic castables