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An experimental program was undertaken to study the mechanical behaviors of glass fiber-reinforced polymer (GFRP) tube confined recycled aggregate concrete with sea sand (GRACSS) under the axial compression. Two different parameters were mainly considered: recycled coarse aggregates (RCA) replacement percentage (0, 100%) and type of sand (sea sand, river sand). Typical influences of RCA and sea sand on the strength, the deformation and the load–deformation curve of GRACSS were investigated. The test results showed that the failure pattern of GRACSS was similar to that of GFRP tube confined ordinary concrete (GCOC). The strength of GRACSS decreased with an increasing RCA replacement percentage, while sea sand could reduce the negative effect of RCA. It is also found that the peak deformation of GRACSS increased with the increasing RCA replacement percentage whereas with decreasing sea sand chloride ion (Cl–) content. The stiffness of the specimen was obviously influenced by the concrete type. Research findings indicated that the axial load-deformation curve of GRACSS can be divided into elastic-plastic and hardening stages. An analytical expression was proposed to calculate the load-deformation curve of GRACSS. Finally, the finite element method (FEM) was applied to study the effects of outer tube thickness, concrete strength, RCA replacement percentage and Cl– content in sea sand on the mechanical behaviors (strength and deformation) of GRACSS. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental study of sea sand recycled concrete filled circular steel tubes (SSRCFSs) under axial compression. The mechanical behaviours of axially loaded SSRCFSs were investigated. Two different parameters were considered: sea sand chloride ion (Cl−) content and recycled coarse aggregate (RCA) replacement percentage. Typical influences of sea sand Cl− and RCA contents on the bearing capacity, deformation and load–deformation curve of SSRCFS were studied. The test results showed that the typical failure mode of the SSRCFSs was similar to that of ordinary concrete filled steel tubes. The axial load–deformation curves of the SSRCFSs could be divided into elastic, plastic growth, declining and steady stages. It was found that the bearing capacity of SSRCFSs increased with decreasing RCA replacement percentage. The effect of sea sand Cl− content on the mechanical behaviour of the SSRCFSs decreased with an increase in RCA replacement percentage. The peak strain of the specimen could be enhanced due to the low modulus of the RCA, but this improvement decreased with increasing sea sand Cl− content. Finally, numerical expressions were developed to obtain the peak load and load–deformation curve of the SSRCFSs. The calculated results were in line with the experimental data. [ABSTRACT FROM AUTHOR]

• Failure of coral concrete was obviously influenced by the mix component. • The stress-strain curve varied with the variation of mix component. • The deformation distribution was slightly changed after using different types of materials. • Seawater changed the crack propagation of CC, while FA partly counteracted the effect of seawater. Typical influences of mix component on the properties of coral concrete (CC) were analyzed in this paper. Different types of fine aggregates (sea sand and river sand), mixing water (seawater and fresh water) and cementitious materials (cement and fly ash) were considered. An experimental system was developed involving uniaxial compression tests and the use of digital image correlation (DIC) method to investigate the deformation distribution and crack propagation of CC. The variations in failure pattern, strength and deformation of CC were studied. Test results indicated that the failure of CC adopting sea sand and seawater was brittle compared to CC using fresh water and river sand. It was found that axial stress-strain curve (SSC) of ordinary concrete (OC) was different from that of CC. The curvature and the descending slope of SSC obviously changed with the variation of mix components. The seawater improved the strength and elastic modulus of CC compared to fresh water, however, the effect of sea sand was negative. It was verified that prismatic compressive strength of CC with fly ash (FA) developed slowly in early stage, while it increased quickly in late stage. After using different types of aggregates, mixing water and cementitious materials, obvious changes were found in the crack propagation and the axial deformation distribution. However, typical influence of mix component on horizontal displacement distribution was negligible. The cracking of CC was seldom observed before the peak stress when compared to OC, and the seawater and sea sand accelerated the CC crack growth after the peak point. Finally, a numerical stress-strain expression of CC considering the influences of mix component was suggested, which could be used in the theoretical analysis and practical design. [ABSTRACT FROM AUTHOR]

The properties of axially loaded sea sand recycled aggregate concrete (SSRAC) were experimentally and theoretically investigated in this paper. The main parameters in the test are the sea sand chloride ions (Cl − ) content and the recycled coarse aggregate (RCA) replacement percentage. The influences of sea sand Cl − and RCA content on the compressive strength, stress-strain relation and failure pattern of SSRAC were studied. Test results showed that both the strength and deformation of specimen changed with the variation of sea sand Cl − content and RCA replacement percentage. The compressive strength of SSRAC was higher than that of ordinary concrete. The elastic modulus increased, while the peak strain decreased due to the effect of sea sand. It was also indicated that the influence of recycled coarse aggregate replacement percentage on the properties of SSRAC decreased with increasing sea sand Cl − content. The Poisson's ratio and stress-strain curve of SSRAC were similar to those of ordinary concrete. Finally, a numerical expression for the stress-strain curves of SSRAC under axial loading was presented, which could be used in the theoretical and practical studies. [ABSTRACT FROM AUTHOR]