Confinement State of Reinforced Concrete Columns Made with Recycled Aggregates

Abstract

Recycled aggregates are one of the options that can be used to form the concrete because they can be considered as environmental-friendly. Using of high replacement ratio of recycled aggregates decreases the compressive strength of the concrete and weakens the rest mechanical properties. This study intended to investigate the effect of the confinement on Reinforced concrete (RC) columns that are made with recycled aggregates since it raises the compressive strength of concrete and improves the behavior of RC columns. This study is analytical and conducted based on the available data in literature of 34 columns that were tested experimentally under axial load only by other researchers, containing various ratios of recycled aggregates. The collected data of axial load capacity are compared with ACI318-19 provisions. It can be used to estimate axial load capacity. Confinement factors are calculated and compared with Mander's formula. It is concluded that Mander's equation can be used after being multiplied by the modification factors derived in this study to better reflect the confinement state. Also, a new formula is derived to estimate the unconfined compressive strength of the concrete based on the used replacement ratio of recycled aggregates.