Research On The Curing And Microscopic Improvement Mechanism Of Graphene Oxide On Waste CRT Glass Mixed With Cement-based Materials

This study systematically investigates the influence of grapheme oxide（GO）addition on the resistance to ionic precipitation and migration of multi-interfacial cement-based materials.By using GO,the toxic substances solidification performance of cement-based materials was improved,promoting the application of recycled toxic industrial wastes in cement-based materials.Waste cathode ray tube（CRT）glass containing approximately 24.52 wt.%of lead is utilized as fine aggregate substitute in cement-based materials,the effect of GO addition on the immobilization of lead and its mechanical properties are further investigated.Firstly,the ionic diffusion resistance of GO modified cement paste in the simulated carbonation environment is studied,and then the Toxicity Characteristic Leaching Procedure（TCLP）test of solid waste is conducted for waste CRT glass cement mortar.It pointed out that the carbonation depth decreased significantly with the increase of GO content in different carbonation periods,especially during the early carbonation period.In addition,GO showed significant inhibition on lead leaching in the specimens with waste CRT glass content of 60 wt.%.The electrochemical and microscopic analysis were carried out to further study the ionic migration and leaching resistance of GO based on the different hydration in cement-based materials.（1）Electrochemical Impedance test（EIS）was carried out to studied the influence of GO on ionic diffusion resistance within the bulk cover and waste CRT glass-mortar multi-interface.The electromagnetic radiation shielding performance was enhanced by coupling use of waste CRT glass and GO on cement composites.Furthermore,the electric permittivity obtained from electrochemical impedance spectroscopy was applied for evaluating the mechanism of electromagnetic radiation shielding improvement by GO and waste CRT glass.The proposed model R0（Q₁W（Q₂R₁）（Q₃R₂））considers the charge interaction in the interface transition zoon（ITZ）of waste CRT glass-mortar.This method is also utilized to evaluate the diffusion of lead ions between various phases in waste CRT glass-mortar influenced by GO.The electrochemical parameters R₁ and R₂ increase with the addition of GO due to the optimization of interface microstructure in waste CRT glass-mortar.Hence,the diffusion of lead ions in the interface of waste CRT glass mortar and the bulk cover is inhibited.The 60 wt.%replacement of waste CRT glass with 0.1 wt.%GO addition increases the relative permittivity by about 50%and 200%.（2）In order to predict the GO influence on hydration degree,nano-indentation and image statistics are carried out to conduct the probability distribution statistical analysis on the microscopic elastic modulus of the hydration phase.The carbonated products of GO cement paste during 28-day carbonization period are explored by the thermogravimetric measurement（TGA）.The influence of GO on the microstructure,carbonation products of cement paste and the ITZ of cement mortar are investigated by the synergistic application of advanced micro technologies including SEM-EDS.Moreover,the role of GO on pore structure of cement paste is also explored.The results showed that the CH content of GO cement paste/mortar at the initial stage of 28-day curing was higher than that of the control specimen based on nano-indentation,thermogravimetric and XRD analysis.The combined results reveal that the GO incorporation can effectively improve the hydration degree of cement paste.During the carbonation period,the ionic transfer and diffusion was inhibited by GO,thus restraining the formation of metastable calcium carbonate compounds.The porosity of cement-based specimens decreases with GO addition,illustrating that GO can enhance the density of cement paste.Meanwhile,the incorporation of GO can optimize the ITZ between the waste CRT glass and bulk cover.Furthermore,no obvious cracks appeared in the cement paste/mortar with GO addition,while the plane shape C-S-H which tended to form a denser hardening structure.