Concretes containing waste-based materials under active confinement

Abstract

The newly developed waste-based concrete (WBC) is a viable eco-friendly and sustainable alternative to conventional concrete, which has the potential of decreasing the negative impact of concrete production on the eco-system. Therefore, understanding the behavior of WBCs in structural applications is important. To this effect, this paper presents the first study on the behavior of actively confined WBC under axial compression loading. Two batches of WBC containing ground granulated blast furnace slag (GGBS) as binder and recycled concrete aggregate as coarse aggregate obtained from construction & demolition (C&D) waste were manufactured using two fine aggregate types, namely glass sand (GS) and lead smelter slag (LSS). WBCs were confined at four confining pressures of 5, 10, 15 and 25 MPa using a Hoek cell, and tests were conducted for assessing the effect of the fine aggregate type and confinement level on the axial compressive behavior of WBCs. The results show that, at a given confining pressure, WBCs containing LSS exhibit higher strength and strain enhancement coefficients compared to WBCs containing GS, indicating that confinement is more effective in the former. The results also show that LSS concrete exhibits an axial stress–strain curve with a slightly less steep post-peak descending branch and slightly higher rate of lateral dilation for a given axial strain compared to GS concrete. The comparison between the predictions by an existing accurate model for conventional concrete and the experimental results of this study reveals that WBC containing LSS under active confinement exhibits similar stress and strain relationships to that of conventional concrete. These results are promising and point to the possibility of utilizing the newly developed WBC in structural columns with lateral confinement.