The mechanism of chloride ion penetration in high performance concrete was analy zed. The experimental results indicate that there are two important reasons that influence the anti-chloride penetration of high perfor...The mechanism of chloride ion penetration in high performance concrete was analy zed. The experimental results indicate that there are two important reasons that influence the anti-chloride penetration of high performance concrete. One is the function effect of mineral functional material, so that it increases conc rete's capability to resist chloride ion penetration. The other is combined acti on of mineral functional material's original capability of binding the chloride ion (physical adsorption) and physicochemical adsorption after hydration.展开更多
The lining concrete of subsea tunnel services under combined hydraulic pressure, mechanical and environmental loads. The chloride ion and water penetrations into concrete under hydraulic pressure were investigated. Th...The lining concrete of subsea tunnel services under combined hydraulic pressure, mechanical and environmental loads. The chloride ion and water penetrations into concrete under hydraulic pressure were investigated. The experimental results indicate that the water penetration depth, chloride ion transportation depth, and the concentration of chloride ion ingression into concrete increase with raised hydraulic pressure and hold press period. But the chloride ion transportation velocity is only 53% of that of water when concrete specimens are under hydraulic pressure. The chloride transportation coefficient of concrete decreases with hold press period as power function. And that would increase 500% 600% in chloride transportation coefficient when the hydraulic pressure increases from 0 to 1.2 MPa. The hydraulic pressure also decreases the bound chloride ion of concrete to about zero. Besides, the low water-cementitions materials and suitable content of mineral admixture(including fly ash and slag) improve the resistance capacity of chloride penetration, and binding capacity of concrete under hydraulic pressure.展开更多
In order to investigate the chloride ion penetration resistance of coal gangue concrete under multi-factor comprehensive action, the non-steady-state accelerated chloride ion migration test was used to test the chlori...In order to investigate the chloride ion penetration resistance of coal gangue concrete under multi-factor comprehensive action, the non-steady-state accelerated chloride ion migration test was used to test the chloride diffusion law of coal gangue concrete specimens by crack width, curing temperature and water-cement ratio. Three groups of crack width (0 mm, 0.05 - 0.12 mm, 0.12 - 0.2 mm), three curing temperatures (high temperature 45, medium temperature 25, low temperature 10), three water cement ratios (0.3, 0.4, 0.5) were set in the experiment. The results show that when the curing temperature and water cement ratio are constant, the crack width less than 0.12 mm has little effect on the chloride content and chloride diffusion coefficient. When the crack width is larger than 0.12 mm, the chloride penetration depth increases with the crack width. The resistance to chloride ion penetration of gangue concrete is greatly influenced by the water cement ratio. The influ-ence degree of three factors on chloride ion migration coefficient of gangue concrete is as follows: water cement ratio > crack width > curing temperature.展开更多
The penetration depth and concentration distribution of implanted ions have been studied for low energy heavy ions implanted in the dry seeds of plant, such as peanut, mung beau, sunflower, wheat and radish seeds, etc...The penetration depth and concentration distribution of implanted ions have been studied for low energy heavy ions implanted in the dry seeds of plant, such as peanut, mung beau, sunflower, wheat and radish seeds, etc. by SEM+EDS. The results .how that the maximum penetration depth is about 12μm for V+ with an energy 200 keV implanted in cotyledon of the peanut, 18pm, spin, 20μm for V2+ with 90 keV implanted in sunflower, wheat, radish seeds, respectively. The penetration depth of implanted Cu2+ with 80 keV is about 90μm in the remainder funicle derivative of the mung beau seeds. The experimental result of the maximum penetration depth of implanted V+ in the peanut seeds was compared with the calculated value of the TRIM95.展开更多
The chloride penetration resistance of cement-based grout materials was improved by nano-silica emulsion.Specimens of mixtures containing different nano-silica particles or emulsions were exposed in sodium chloride so...The chloride penetration resistance of cement-based grout materials was improved by nano-silica emulsion.Specimens of mixtures containing different nano-silica particles or emulsions were exposed in sodium chloride solutions of specific concentrations with different test ages.Hardened properties of the mixes were assessed in terms of weight loss and compressive strength.X-ray diffraction(XRD)and scanning electron microscopy(SEM)of mixes were performed to analysis the phase evolution and microstructure.The results demonstrated that the introduction of nano-SiO_(2) emulsion significantly decreased the compressive strength loss and calcium hydroxide(CH)crystal content of hydration production,and then enhanced the resistance of cement-based grouting materials to chloride ion penetration.This improvement derives from the filling and pozzolanic effects of nano-SiO_(2) particles,which were incorporated via an emulsion and attributed to a well dispersion in grouting matrix.展开更多
To answer the queries concerning penetrability of ~1 μT, physiologically patterned, time-varying magnetic fields through the cranium, the proportions of attenuation through thicknesses and densities of ~3 times that ...To answer the queries concerning penetrability of ~1 μT, physiologically patterned, time-varying magnetic fields through the cranium, the proportions of attenuation through thicknesses and densities of ~3 times that of the human skull were measured directly. There was no reduction in the intensity of the magnetic field when two 2 cm thick dried pine boards (4.3 × 103 kg·m-3) were placed between the pairs of solenoids separated by the approximate width of the skull. Although volumes of water containing intracellular concentrations of ions did not attenuate the field intensity, placement of 290 cm2 of 2 mm sheets of duct metal reduced the amplitude by 25%. Spectra comparisons showed a clear congruence in profiles between direct measurement of the applied field and the original computer-generated pattern. These results indicate there is little validity to claims that weak, time-varying magnetic fields applied in this manner are eliminated or significantly attenuated by the human skull.展开更多
基金Funded by the Country Project of Tacking Key Problem for Fif teen Plan(No.2001BA307B05 08)
文摘The mechanism of chloride ion penetration in high performance concrete was analy zed. The experimental results indicate that there are two important reasons that influence the anti-chloride penetration of high performance concrete. One is the function effect of mineral functional material, so that it increases conc rete's capability to resist chloride ion penetration. The other is combined acti on of mineral functional material's original capability of binding the chloride ion (physical adsorption) and physicochemical adsorption after hydration.
基金Projects(50708046,51178230)supported by the National Natural Science Foundation of ChinaProject(2009CB623203)supported by the National Basic Research Program(973 Program)of ChinaProject(2010CEM006)supported by State Key Lab of High Performance Civil Engineering Materials,China
文摘The lining concrete of subsea tunnel services under combined hydraulic pressure, mechanical and environmental loads. The chloride ion and water penetrations into concrete under hydraulic pressure were investigated. The experimental results indicate that the water penetration depth, chloride ion transportation depth, and the concentration of chloride ion ingression into concrete increase with raised hydraulic pressure and hold press period. But the chloride ion transportation velocity is only 53% of that of water when concrete specimens are under hydraulic pressure. The chloride transportation coefficient of concrete decreases with hold press period as power function. And that would increase 500% 600% in chloride transportation coefficient when the hydraulic pressure increases from 0 to 1.2 MPa. The hydraulic pressure also decreases the bound chloride ion of concrete to about zero. Besides, the low water-cementitions materials and suitable content of mineral admixture(including fly ash and slag) improve the resistance capacity of chloride penetration, and binding capacity of concrete under hydraulic pressure.
文摘In order to investigate the chloride ion penetration resistance of coal gangue concrete under multi-factor comprehensive action, the non-steady-state accelerated chloride ion migration test was used to test the chloride diffusion law of coal gangue concrete specimens by crack width, curing temperature and water-cement ratio. Three groups of crack width (0 mm, 0.05 - 0.12 mm, 0.12 - 0.2 mm), three curing temperatures (high temperature 45, medium temperature 25, low temperature 10), three water cement ratios (0.3, 0.4, 0.5) were set in the experiment. The results show that when the curing temperature and water cement ratio are constant, the crack width less than 0.12 mm has little effect on the chloride content and chloride diffusion coefficient. When the crack width is larger than 0.12 mm, the chloride penetration depth increases with the crack width. The resistance to chloride ion penetration of gangue concrete is greatly influenced by the water cement ratio. The influ-ence degree of three factors on chloride ion migration coefficient of gangue concrete is as follows: water cement ratio > crack width > curing temperature.
基金the National Natural Science Foundation (No. 19890303)
文摘The penetration depth and concentration distribution of implanted ions have been studied for low energy heavy ions implanted in the dry seeds of plant, such as peanut, mung beau, sunflower, wheat and radish seeds, etc. by SEM+EDS. The results .how that the maximum penetration depth is about 12μm for V+ with an energy 200 keV implanted in cotyledon of the peanut, 18pm, spin, 20μm for V2+ with 90 keV implanted in sunflower, wheat, radish seeds, respectively. The penetration depth of implanted Cu2+ with 80 keV is about 90μm in the remainder funicle derivative of the mung beau seeds. The experimental result of the maximum penetration depth of implanted V+ in the peanut seeds was compared with the calculated value of the TRIM95.
基金Funded by a Science and Technology Project from the Ministry of Housing and Urban-Rural Development of the People’s Republic of China(No.2019-K-047)Yangzhou Government-Yangzhou University Cooperative Platform Project for Science and Technology Innovation(No.YZ2020262)。
文摘The chloride penetration resistance of cement-based grout materials was improved by nano-silica emulsion.Specimens of mixtures containing different nano-silica particles or emulsions were exposed in sodium chloride solutions of specific concentrations with different test ages.Hardened properties of the mixes were assessed in terms of weight loss and compressive strength.X-ray diffraction(XRD)and scanning electron microscopy(SEM)of mixes were performed to analysis the phase evolution and microstructure.The results demonstrated that the introduction of nano-SiO_(2) emulsion significantly decreased the compressive strength loss and calcium hydroxide(CH)crystal content of hydration production,and then enhanced the resistance of cement-based grouting materials to chloride ion penetration.This improvement derives from the filling and pozzolanic effects of nano-SiO_(2) particles,which were incorporated via an emulsion and attributed to a well dispersion in grouting matrix.
文摘To answer the queries concerning penetrability of ~1 μT, physiologically patterned, time-varying magnetic fields through the cranium, the proportions of attenuation through thicknesses and densities of ~3 times that of the human skull were measured directly. There was no reduction in the intensity of the magnetic field when two 2 cm thick dried pine boards (4.3 × 103 kg·m-3) were placed between the pairs of solenoids separated by the approximate width of the skull. Although volumes of water containing intracellular concentrations of ions did not attenuate the field intensity, placement of 290 cm2 of 2 mm sheets of duct metal reduced the amplitude by 25%. Spectra comparisons showed a clear congruence in profiles between direct measurement of the applied field and the original computer-generated pattern. These results indicate there is little validity to claims that weak, time-varying magnetic fields applied in this manner are eliminated or significantly attenuated by the human skull.
