Mechanical behaviour of seawater sea-sand recycled coarse aggregate concrete columns under axial compressive loading

Abstract

The use of locally available seawater and sea-sand to produce seawater sea-sand concrete (SSC) is promising in marine and coastal projects. This paper investigates the mechanical behaviour of SSC columns that are prepared with recycled coarse aggregates (SSRAC). The results demonstrate that the seawater-sea-sand-based concrete column behaves similarly to conventional natural aggregate concrete (NAC) when the shell content in sea-sand equals 2.31%. SSRAC columns outperform RAC columns in terms of strength and deformability with a peak load capacity that is approximately 17% higher. Based on the monolithic specimens, the SSRAC composite concrete column is realized by confining the SSRAC core using steel-reinforced NAC or an engineered cementitious composite (ECC) shell. Compared with monolithic specimens, the peak load capacity of the NAC-SSRAC composite column is similar, whereas that of the ECC-SSRAC column is 15% higher. It is feasible to use the ECC shell without stirrups to confine SSRAC. Furthermore, the applicability of available stirrup-confined concrete stress-strain models on the SSRAC and its composite concrete columns is evaluated.