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Improved Mechanical Behaviour and Microstructure of Cemented Soil with Nanomaterials
Jianguo Lu,Huayan Yao,Isam Shahrour,Qingyao Fang,Weilong Song,Guang Liu 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.7
This paper presents an experimental study of nanomaterials' influence on improving the mechanical behaviour and microstructure of cemented soils. The strength characteristics were obtained through uniaxial compressive strength test. The influences of nanomaterials on the pore size distribution and micromorphology of cemented soil were investigated by nuclear magnetic resonance, scanning electron microscope, and X-ray diffraction. The results show that the uniaxial compressive strength of the cemented soil increases with the nano-SiO2content. When the content is 4%, the strength of the cemented soil increases by about 40%. Improvement with nano-Fe3O4 shows different trends. The strength of the cemented soil increases with the nano-Fe3O4 content, reaching a peak at 3% of the nano content, and then decreases with the increase in the content. The transverse relaxation time spectrum curve of the cemented soil is trimodal, and the main peak covers a dominant area. Adding nanomaterials improves the pore distribution, transforms large pores into small pores, and greatly reduces the pores of the cemented soil. The porosity of the cemented soil decreases exponentially with the increase of nano-SiO2 content. On the contrary, with the increase of nano-Fe3O4 content, the porosity of the cemented soil specimen first decreases and then increases, the porosity reaches the minimum at 3% content. Nano-SiO2 and nano-Fe3O4 can effectively fill the internal pores of the cemented soil and accelerate the hydration process. In addition, nano-SiO2 participates in the hydration reaction of cement and has a good promoting effect on the mechanical properties of cemented soil.
Yu Wu,Zhaojun Wu,Kai Liu,Fu Li,Yujie Pang,Jianbin Zhang,Huayan Si 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.10
This work presents a simple method for the preparation of the Mg-doped nanocomposite copper silicates (Mgx-Cu1x-SiO3) (x=0.25, 0.5, 0.75 and 0.9) using coal gangue waste as the silicon source for CO2 capture at low temperature. The as-prepared Mgx-Cu1x-SiO3 was systemically characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller surface area analysis (BET). The results suggest that all Mgx-Cu1x-SiO3 possess large surface areas, micropores and mesoporous structures composed of the agglomerates of small nanoparticles. They exhibit high CO2 adsorption capacity at 298.15 K under 1 bar, and that of Mg0.9-Cu0.1-SiO3 was the highest with the value of 16.73 cm3/g. The Freundlich isotherm model fits the CO2 adsorption isotherm well. Thermodynamic analysis indicates that the CO2 adsorption on Mg0.9-Cu0.1-SiO3 is exothermic (Ho<0), chaotic (So<0), and spontaneous (Go<0). This work highlights the low-temperature adsorption behavior of silicate materials on CO2, which can provide some research basis for the utilization of silica in coal gangue.