Bond strength properties of confined and unconfined coconut shell aggregate concrete by beam splice test

This study investigates the bond strength properties of a green concrete produced by replacing the coarse aggregate by an agricultural by product, coconut shell (CS). The bond between steel reinforcement and coconut shell aggregate concrete was studied by using 60 numbers of beam splice specimens. Confined and unconfined beam splice specimens were used. The effects of rebar diameter of lap splice and types of aggregate were investigated. It was observed that the percentage reduction in bond stress for 16 mm rebar unconfined beam splice specimens for various percentage replacements of CS from 25% to 100%, lies in the range of 6-8% compared to 12 mm rebar specimens. Whereas, for confined beam splice specimens the range of percentage reduction is 6-10%. For unconfined and confined beam splice specimens, percentage reduction in bond stress for 25% to 100% replacement by CS for each 25% increment was approximately in the range of 2-3%, 20-23%, 31-34% and 47-48% respectively with respect to normal concrete for both 12mm and 16mm rebar specimens. The percentage increase in bond stress by confining the specimens for various percentage replacements of CS and different size rebar lies in the range of 52-58%. Keywords: coconut shell aggregate concrete, bond strength of concrete, beam splice test