In this paper, the effect of GO/Al2O3 and Al2O3 synthesized nanoparticles on the durability of concrete is studied. To this end, after the synthesis of nanoparticles and confirmation of nanoparticles fabrication by SEM and FT-IR spectra, three concrete samples for each experiment related to each mix design were prepared and subjected to freeze-thaw cycles, high temperature, and acidic environment. The results show that the samples containing GO/Al2O3 nanoparticles had the least weight loss in freeze-thaw cycles as well as better resistance against acidic environment and the lowest apparent changes at high temperature compared to the samples containing nano-Al2O3 and the samples without nanoparticles. The replacement of 2 wt.% of cement with GO/Al2O3 nanoparticles results in the highest increase in concrete durability. The presence of nanoparticles in the concrete microstructure and the validation of the results are investigated by FT-IR, SEM, and EDX spectra.

Recent research in the construction industry justifi es the partial replacement of cement by nanomaterials. Graphene oxide na-nocomposite is a material that has been recently proposed as a suitable alternative for part of cement in concrete. However, there is no research on the addition of these synthetic compounds to concrete, and little is known about the effect of these materials on the mechanical and durability properties of concrete. Therefore, in this laboratory study, the synthesis of Fe3O4/SiO2/GO and GO nanoparticles was performed and confi rmed with FT-IR, SEM, TEM analyses. These nanoparticles partially replaced cement by 1, 2, 3, and 4 % by mass of the cement, and their effect on mechanical and durability properties of concrete at the ages of 7, 28, and 90-day, were investigated. The results suggest that mixtures in which 2% Fe3O4/ SiO2/GO and 3% GO substituted cement yielded the best results in the mechanical properties tests. Concrete containing Fe3O4/SiO2/GO nanoparticles enhanced compressive strength by 14% and splitting tensile strength by 12% after 28-days of curing. Also, concrete containing 2% Fe3O4/SiO2/GO, had the highest re-sistance to an acidic environment, the lowest permeability, and the highest transient pulse velocity in the ultrasonic test, compared to the specimen containing GO nanoparticles and the control sample.