Reinforced concrete (RC) exerts its structural performance due to the bond stress between rebar and concrete. According to the past research, rebar corrosion is thought to lead to a decrease in bond performance of RC. In order to improve corrosion resistance of rebar, hot-dip galvanized rebar has been developed and put into practical use as one of RC anticorrosion technologies. Hot-dip galvanized rebar is a rebar coated with a thin hot-dip galvanized layer on the surface. On the other hand, it is not clear whether the galvanized coat formed on the surface of the rebar affects the bond performance between concrete and rebar.
The purpose of this study is to evaluate the bond performance of hot-dip galvanized rebar embedded in reinforced concrete. The bond stresses between rebar and concrete under compressive, tensile, and bending and shearing stress field were investigated by measuring the stress distribution along the rebar embedded in concrete using neutron diffraction method. The neutron diffraction method for measuring stress is one of the complete non-destructive and non-contact measurement technologies that utilize the diffraction phenomenon of neutron rays. By taking advantage of the excellent permeability of neutron rays, it is possible to evaluate the stress state in the deep part of the material quantitatively. The series of experiments in this study was conducted at the engineering diffractometer, TAKUMI, in MLF, J-PARC, Japan.
In Chapter 3, the bond performance of hot-dip galvanized rebar embedded in concrete at a compressive stress field was evaluated. As a result, for both introduced stresses (195MPa and 250MPa), the stress distribution along the hot-dip galvanized rebar was almost the same as that of ordinary rebar, and the difference in average bond stress was within 5%.
In Chapter 4, the bond performance of hot-dip galvanized rebar embedded in concrete at a tensile stress field was evaluated. As a result, although the approximate stress distribution along hot-dip galvanized rebar had a little difference compared with that of ordinary rebar due to the degree of cracking, the difference in average bond stress between these was within 10%.
In Chapter 5, the bond performance of hot-dip galvanized rebar embedded in concrete at a bending and shearing stress field was evaluated. As a result, for both introduced stresses (140MPa and 280MPa), the approximate stress distribution along hot-dip galvanized rebar was almost the same as that along ordinary rebar, and the difference in average adhesive stress was less than 10%.
In conclusion, the present study has demonstrated that the bond performance of hot-dip galvanized rebar was equivalent to that of ordinary rebar. In addition, it was found that the neutron diffraction technique could be a useful technique to evaluate the anchorage performance. Furthermore, further studies are needed in order to elucidate of structural performance of larger members.
