Bond testing of salty-sand concrete reinforced with different rebars

Abstract

In this work, reinforced concrete (RC) test specimens, cast with different rebars (CA-50 Steel, Basalt Fiber Reinforced Polymer – BFRP and Glass Fiber Reinforced Polymer – GFRP) and different concrete mixtures (salty-sand and unsalty sand), were submitted to the pull-out tests in order to follow the bonding behavior between the concrete and the rebar. The use of salty-sand in concrete mixtures for building construction has grown, especially in places where regular sand is scarce. However, the salinity attacks the steel rebar in RC structures, resulting in corrosion problems, which can be strongly reduced by using composite material rebars which shows, similar or superior, mechanical strength, when compared to steel rebars. Conformance testing, including X-ray powder diffraction (XPD), scanning electronic microscopy (SEM) and tensile tests, were performed on the rebars, with the aim to check the conformity of the physical, chemical and mechanical properties. Standard cylindrical test specimens (diameter of 100 mm and a height of 200 mm) and RC test specimens were prepared for compression and pull-out tests performed at 63, 217 and 315 days, after casting. The results showed a bonding loss for the RC test samples molded with CA-50 steel rebar and salty-sand concrete. On the other hand, bonding loss was not detected for test samples molded with BFRP and GFRP rebars. In conclusion, the BFRP and GFRP rebars showed to be the proper ones to be used for salty-sand concrete mixtures, however, even having higher traction resistance, their use in the RC structures will demand higher anchor lengths.

Keywords

• concrete structures
• chloride-induced corrosion
• bond stress
• frp
• pull-out resistance