Mechanism Study of Graphene Oxide Recycled Concrete on Carbonation Resistance

Abstract

Rapid carbonation test of recycled concrete specimens with graphene oxide (GO) contents of 0, 0.03, 0.06, and 0.09% are carried out. The hydration products, micropore distribution, and micromorphology of recycled concrete specimens are characterized by performing thermogravimetric analysis, X-Ray Diffraction (XRD), a mercury intrusion test, and scanning electron microscopy (SEM). The results show that the carbonization resistance of recycled concrete specimens mixed with GO has been improved to varying degrees compared with that of ordinary recycled concrete specimens. When the GO content was 0.06%, the improvement effect was the best. This improvement is attributed to the improvement of the microstructure and pore characteristics of recycled concrete owing to the presence of GO. In the microstructure of recycled concrete specimens with GO, the shape of hydrated crystals is more regular and the section is more compact. In microscopic pores, the ratio of harmful pores and multiple harmful pores is effectively controlled. In this work, the multiscale characterization of the test specimens from the micro to mesolevel is realized by combining various technical approaches. The influences of different GO contents on the carbonization resistance of recycled concrete are proven, and the mechanism responsible for improving the carbonization resistance of recycled concrete is explored.