PhD Dissertation Oral Defence, Charles Rockson: Bond Behaviour Of Commercially Produced Structural Concrete Made OF Recycled Coarse And Fine Aggregates

Doctoral Dissertation Oral Defence – Doctor of Philosophy in Civil Engineering

Charles Rockson will defend the dissertation titled:

Bond Behaviour Of Commercially Produced Structural Concrete Made OF Recycled Coarse And Fine Aggregates

Recycled concrete aggregates (RCAs) offer a sustainable solution to the multifarious exigent crises involving the ever-increasing demand of virgin aggregates and the disposal of construction and demolition waste arising from demolishing non-serviceable infrastructures. However, the use of RCA in concrete is mostly limited to non-structural purposes at a limited replacement proportion of the virgin aggregates in the standards and codes. Also, using an appropriate test method to quantitatively determine the bond behaviour of steel rebar in recycled structural concrete in addition to the other several variables affecting the bond remains unexplored. This study presents the results of an experimental program on the bond behavior between commercially produced quality recycled concrete and deformed steel rebars.

Seventy beam-end specimens were tested using the ASTM A944-15, where critical variables affecting bond behaviour, such as cover, bond length, bar size, bar position, and transverse reinforcement were investigated. The results showed that the bond strengths were conservative with several descriptive and code design equations, as well as fitting into the current ACI408 database for conventional concrete. In addition, a new descriptive model was also proposed and validated. Thus the bond concerns on using quality recycled aggregates as structural concrete have been scrutinized in this study.