چكيده به لاتين
Graphene oxide (GO) as a two-dimensional carbon nanomaterial is a promising candidate for reinforcing cement composites owing to its extraordinary mechanical properties. Despite the desirable dispersion of GO in aqueous solutions, the existence of multivalent Ca2+ cations besides the high alkalinity of cementitious environments causes the severe agglomeration of GO nanosheets and consequently their unfavorable dispersion. Although it has been shown that the dispersion of GO nanosheets in cementitious environments can be ameliorated using surfactants, due to their organic origin, most of them are incompatible with the cement hydration products and their use can lead to the formation of pores in the cement matrix. Therefore, in the present study, the potential of the different weight ratios of trass as a pozzolanic material for improving the dispersion of GO nanosheets in alkaline cementitious environments was investigated. Additionally, the interaction between trass microparticles and GO nanosheets in water as well as their synergic influence on the mechanical properties of cement paste was also evaluated. It is noteworthy to mention that the dispersion of trass-GO hybrid in aqueous and alkaline cementitious solutions was assessed by conducting the pH measurements, visual investigation, UV-vis spectroscopy, zeta potential analysis and SEM characterization. The result of pH and zeta potential measurements in water revealed that the stability of GO nanosheets improved with the incorporation of trass particles; especially, in the case of trass/GO equal to 600. Moreover, the result of UV-vis spectroscopy on trass-GO suspensions represented a descending trend in the absorbance peak with an increase in the trass/GO weigh ratio which could be due to the adsorption process between GO nanosheets and trass particles. However, the result of visual investigation, UV-vis spectroscopy, and zeta potential measurements on the trass-GO hybrid in cement pore solution demonstrated their agglomeration and instability which was further analyzed by SEM. Finally, the incorporation of trass-GO hybrid in cement paste samples improved the compressive strength of samples by 60.6%, 48.6%, and 20.9 % at 7, 28, and 90 days, respectively; compared with the plain samples. However, the reinforcing effect of trass-GO hybrid on flexural strength of samples was not noticeable.
