Photocatalytic,Hydrophobic And Other Functional Cement-based Materials

Cement is the most used building material,and its functional development is of great concern to researchers.The implementation and development of green buildings are the theme of the future development of the world’s construction.The development of environment-friendly materials is the development trend of cement.Currently,there are many functional cement,such as translucent cement concrete,conductive cement concrete and photocatalytic cement concrete.Combining with the development of green building and considering the current status of the research on the function of cement,this paper proposed the function of self-cleaning hydrophobicity,the photo-catalytic performance and the removal of heavy metal ions in water of cement accord-ing to the principle of green building.We observed the microstructure of the prepared functional cement and its components,in-depth analysis of its chemical functional characteristics of the mechanism,and measured the corresponding functional proper-ties of the actual effect test.The specific research contents and results were as follows:（1）The microstructure of the lotus leaf surface was replicated to the surface of Portland cement by nanocasting technology,which made the surface of the cement with lotus leaf microstructure.The Portland cement with superhydrophobic properties was successfully fabricated.The morphology and structure of the surface of lotus leaf,Pol-ydimethylsiloxane（PDMS）and Portland cement with different viscosity were analyzed by Environmental Scanning Electron Microscope（ESEM）.The hydrophobicity prop-erties of superhydrophobic cement was measured by water contact angle.The self-cleaning properties of superhydrophobic cement measured by"T"labeled experiment.The experimental results showed that the water contact angle of the superhydrophobic cement surface was about 140°for the best sample.In addition,we measured that the rolling angle of the cement surface was less than 5°,which further confirmed the su-perhydrophobic properties of the cement surface.（2）Ag/AgBr/MOC composites were successfully prepared and their photocata-lytic activity was studied.Based on this material,magnesium oxychloride cement（MOC）cement material art vial was prepared.The crystal types of MOC cement were analyzed by X-Ray Diffractometer（XRD）.The surface information and light absorp-tion properties of Ag/AgBr/MOC composites were analyzed by scanning electron mi-croscope（SEM）,X-ray photoelectron spectroscopy（XPS）and UV-vis diffuse reflec-tance spectroscopy.Formaldehyde gas was used to evaluate the Ag/AgBr/MOC Pho-tocatalytic activity of composite materials and MOC cement art vial.The experimental results showed that MOC cement provided a 3D network structure,which mainly com-posed of acicular structure phase 5.The deposition of AgBr nanoparticles was carried out by spraying a suspension of AgBr nanoparticles at about 200 nm on the MOC ce-ment substrate.UV-vis spectroscopy and XPS showed that AgBr produced metallic Ag nanoparticles under illumination.Samples prepared under natural light and UV light showed high formaldehyde removal.The sample with H₂O/MgO molar ratio of 14showed higher degradation efficiency than the other samples.MOC cement material art vial was photocatalytically degraded for formaldehyde to completely decontaminate the initial concentration of 50 ppm formaldehyde in two days at room temperature.（3）T-FA composites were prepared by organic-inorganic hybrid method using al-kali-activated fly ash（FA）modified with 3-thiocyanato-propyltriethoxysilane（TCPS）,and T-FA composites was incorporated into pervious concrete to prepare functional materials to remove heavy metal ions in the environment.The surface morphology and structure of T-FA were analyzed by SEM,fourier transform infrared spectroscopy（FI-IR）,thermogravimetric-differential scanning calorimetry（TG-DSC）and nuclear mag-netic resonance（NMR）.The T-FA composites and incorporation of T-FA pervious ce-ment were analyzed by the experment of removal of heavy metal ions Cd（Ⅱ）.The experimental results showed that FA was excited by alkali and SiOH was formed on the surface of the FA.Alkali-excited FA beads showed a new infrared peak.The asym-metric vibrational peak of-CH₂ in TCPS molecule appears at 2976 cm^-1 and the-CN peak appears at 2995 cm^-1.²⁹Si NMR showed the change from Q₄[（SiO）₂Si（OSi）₂]to Q₂[（SiO）₂Si（OH）₂],indicating that the silicon-oxygen bond was decomposition into si-lanol bond after excited by the base alkali.By incorporating T-FA beads,pervious con-crete with heavy metal removal capability was successfully prepared.The 10×10×10cm³ cube concrete could fix Cd（Ⅱ）in 5 L solution and reduce Cd（Ⅱ）from 300 ppm to15.86 ppm.