Abstract: A refractory composition is disclosed which possesses low porosity, high density, exceptional strength and high abrasion resistance and is useful for lining fluid catalytic converter units, e.g., catalyst transfer lines, riser lines, J-bends, cyclones and all other areas where hot abrasion resistance and low thermal conductivity are desired. The composition consists essentially of by weight: (a) 44 to 89% of an abrasion-resistant refractory grain; (b) 10 to 50% of a hydraulically setting cement; (c) 1 to 6% of a filler consisting of very fine, substantially spherical particles of a metal oxide selected from the group consisting of Al.sub.2 O.sub.3, Cr.sub.2 O.sub.3, ZrO.sub.2, TiO.sub.2, clay minerals, carbon and fume SiO.sub.2 ; and (d) 0.01 to 1%, based on the total weight of the constituents (a), (b) and (c), of additives selected from deflocculants and wetting agents.