Bond of steel reinforcement in different lightweight aggregate concretes

Nowadays both concrete and reinforcing steel are of significant interest in research and development, including the question of bond between concrete and reinforcing materials. Steel bars and non metallic bars are studied in details, but the composition of the concrete is rarely investigated as a varying parameter. Earlier literature data discussed only compressive strength grade up to B200 (cca. LC12-LC16). Many recent publications mainly compare the bond strength with only concrete strength grade, and do not examine the type of aggregate. Our research focused on the bond between lightweight aggregate concrete (LWAC) and deformed steel bar (BSt 500 S) with standard pull-out test. The variable parameter was the type of aggregate: expanded clay gravel and sand, expanded glass gravel, crushed ceramic brick gravel and sand, as well as natural quartz gravel and sand for reference. The compressive strength of lightweight aggregate concrete is lower than the compressive strength of a normal weight concrete with the same cement and water content and same volume of aggregate. Our experiments resulted that the ratio between bond strength and compressive strength is not significantly different in case of lightweight aggregate concrete compared to normal weight concrete. In case of full lightweight aggregate content (as fine and coarse aggregate) this ratio can be higher than that of normal weight concrete.