UBC Theses and Dissertations

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UBC Theses and Dissertations

Bond behaviour of commercially produced structural concrete from recycled coarse and fine aggregates Rockson, Charles


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 infrastructure. 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 other several variables affecting the bond remains unexplored. This study presents the results of an experimental program on the bond behaviour between commercially produced quality recycled concrete and deformed steel rebars. Seventy beam-end specimens were tested using the ASTM A944-15, where five critical variables affecting bond behaviour, such as cover, bond length, bar size, bar position, and transverse reinforcement were investigated. For the five variables investigated, the normalized bond strengths of recycled concrete mixes were generally comparable to the conventional natural concrete mixes. Furthermore, the results showed that the bond strengths were conservative with several descriptive and code design equations, as well as fitting into the current ACI 408 database for conventional concrete. Finally, a new descriptive model equation was proposed and validated using the experimental results.

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