چكيده به لاتين
Many studies have been conducted on the use of graphene oxide nanomaterials in cement composites. The results show that the mechanical properties of the cement composites, including these nanomaterials, have improved. Although using graphene oxide in cement composites is appropriate, it agglomerates in cementitious alkaline environments. This agglomeration reduces the reinforcing properties of this nanoparticle, and as a result, agglomeration of graphene oxide in alkaline environments is one of the challenges related to this nanoparticle’s use. Using surfactants leads to better dispersion of graphene oxide in alkaline environments, but these materials do not have good adaptability with cement hydration products; thus, using many of them is not suggested. Pozzolans are among the materials used with graphene oxide and have been proposed in previous research as an option to improve the dispersion of graphene oxide in alkaline environments. In this research, zeolite was used to investigate the dispersion of graphene oxide in aqueous and alkaline environments. Like graphene oxide, this pozzolan leads to the improvement of mechanical properties and especially durability of cement composites and is a good candidate for using in cement composites. Therefore, in this study, first, the effect of zeolite on the dispersion of graphene oxide in aqueous and alkaline environments was investigated, and then the mechanical properties of the sample containing both materials were explored. The results of experiments such as visual investigation, UV-Vis spectroscopy, pH measurements, zeta potential, particle size distribution, and scanning electron microscopy imaging showed an apt dispersion of graphene oxide – zeolite hybrid in aqueous environments; however, the results of the mentioned experiments in high alkaline environments indicated the low effect of zeolite to prevent graphene oxide from agglomeration. In the study of mechanical properties of cement paste samples, the compressive and flexural strength of cement paste samples containing graphene oxide and zeolite were investigated. Samples containing both graphene oxide and zeolite improved compressive strength by 43.5%, 18.5%, and 18.8% compared to the control sample at the ages of 7, 28 and 90 days, respectively. Also, the flexural strength of samples containing both graphene oxide and zeolite increased by 19.7%, 28.6%, and 23.1% compared to the control sample, at the ages of 7, 28 and 90 days, respectively. The results of this study can help to more efficient use of graphene oxide nanosheets in cement matrices.
