Bond behavior between BFRP bar and basalt fiber reinforced seawater sea-sand recycled aggregate concrete

In order to meet the demand of construction waste treatment and using local materials, the use of recycled coarse aggregate (RCA), sea-sand and seawater is of great significance to coastal areas and sea related engineering construction. Basalt fiber (BF) reinforced seawater sea-sand recycled aggregate concrete (BFSSRAC) with good workability was prepared in this paper. The mechanical properties of BFSSRAC and bond behavior between BFRP bar and BFSSRAC were investigated considering the effects of BF content and concrete strength through a series of tests and microstructure analysis. The results showed that the combination use of BF, seawater, sea-sand and RCA could reduce the adverse effects of RCA on the mechanical property of concrete. SEM analysis showed that the addition of BF could effectively improve the pore structure of concrete matrix, especially the interfacial transition zone (ITZ). The usage of RCA reduced the bond strength between BFRP bar and RAC, while the usage of seawater and sea-sand had little effect on the bond-slip constitutive relation. After adding BF, the ultimate bond strength and maximum slip of BFSSRAC were larger than those of concrete without fibers and increased with the increasing BF content. Based on the experimentally obtained tau-s curves, the bond-slip constitutive relation model between BFRP bar and BFSSRAC was proposed, and the model was verified by deviation analysis between calculated and measured values. The findings of this study can provide new and meaningful reference for the application of BFSSRAC structures reinforced with BFRP bars. (C) 2021 Elsevier Ltd. All rights reserved.