To make backfilling body meet strength requirement,physical-chemical evaluation and proportioning tests were conducted on several backfilling materials.Jigging sands,#32.5 cement and fly ash were determined as backfil...To make backfilling body meet strength requirement,physical-chemical evaluation and proportioning tests were conducted on several backfilling materials.Jigging sands,#32.5 cement and fly ash were determined as backfilling aggregate,binding material and modified material,respectively.An optimized proportion of backfilling materials with a solid mass fraction of 78%and cement:fly ash:jigging sands mass ratio of 1:2:14,was suggested to Jiangan Pyrite Mine,China.The slurry made by optimized proportion produced obvious shear thinning phenomena,and was confirmed as paste-like slurry.To analyze its rheological characteristics,L-type pipeline test and Haake VT550 rotational viscometer test were conducted.Bingham and Casson fluid models were applied to several paste-like slurry samples to simulate flow and stress states;Casson fluid model was proved to have better simulation effect on paste-like slurry with shear thinning phenomena;rheological parameters of backfilling slurry made by suggested proportion were measured.Initial yield stress,average apparent viscosity and limiting viscosity are 55.35 Pa,1.216 Pa-s and 0.48 Pa-s,respectively.Compared with Bingham fluid model,Casson fluid model has a better simulation effect on paste-like slurry with shear thinning phenomena,through calculating the residual standard deviations.展开更多
An Al2O3 protective coating on magnesium alloy AZ31 was prepared by a repeated direct sol-gel process annealing at 300℃and a composite coating was also deposited using Al2O3 particles dispersed sol followed by phosph...An Al2O3 protective coating on magnesium alloy AZ31 was prepared by a repeated direct sol-gel process annealing at 300℃and a composite coating was also deposited using Al2O3 particles dispersed sol followed by phosphating treatment and annealing at 300℃.The morphologies,structures and critical adhesive loads as well as corrosion properties of the coatings were comparatively investigated by scanning electron microscopy(SEM),X-ray diffractometry(XRD),nanoscratch test and electrochemical measurement.The results show that the composite coating has a more uniform,crack-free layer and improved adhesion to the substrate as compared with that of the repeated direct sol-gel coating owing to its lower heat strain.The main phases in both coatings consist ofγ-Al2O3 andδ-Al2O3 derived from annealed alumina sol,and the composite coating has an anticorrosion performance which is superior to that of the repeated direct sol-gel coating.展开更多
In order to determine the effects of different mineral admixtures including fly ash （FA）, blast furnace slag （BFS） and metakaolin （MK） on hydration product phases from the nanoscale structure perspective, nanoin...In order to determine the effects of different mineral admixtures including fly ash （FA）, blast furnace slag （BFS） and metakaolin （MK） on hydration product phases from the nanoscale structure perspective, nanoindentation characteristics of the samples with similar 28-day strengths have been investigated. The results indicate that the volume fractions of porosity in po- rosity and hydration product phases of the samples with the same kind of mineral admixture are almost equal to each other, and are greater than that of the sample without mineral admixture. Mineral admixtures especially MK can decrease remarkably the volume fractions of CH in porosity and hydration product phases, and there exists a good linear relationship between the （AI＋Si）/Ca molar ratio of cementitious materials chemical compositions and the volume fraction of HD C-S-H gel in C-S-H gel. Therefore, it is possible to predict the volume fraction change of HD C-S-H gel in C-S-H gel by simply calculating the （AI＋Si）/Ca molar ratio of cementitious materials with similar 28-day strengths under the constant water-binder ratio.展开更多
Bioaerosol, an important constituent of the atmosphere, can directly affect light radiation characteristics due to absorption and scattering effects. Current research lacks a reasonable explanation for the extinction ...Bioaerosol, an important constituent of the atmosphere, can directly affect light radiation characteristics due to absorption and scattering effects. Current research lacks a reasonable explanation for the extinction abilities of bioaerosols in a broadband. Herein, we measured the reflectance spectra of 12 com m on biomaterials and calculated their complex refractive indexes. The peaks of the imaginary part of the complex refractive indexes are located at wavelengths of approximately 0.7, 2.7, 6.1 and 9.5μm. Based on photographs of the floating structures of bioaerosols, we constructed a model for calculating the extinction abilities of bioaerosols in the wavelength range of 240 nm to 14 (im. Taking AN02 spores as an example, absorption was found to account for more than 90% of the total extinction. In addition, the theoretical calculations and experimental data of transmittance corresponding to the smoke box show that bioaerosol exhibits significant broadband extinction ability from UV to IR bands, which provides new directions for the development of broadband light attenuation materials.展开更多
基金Project(2012BAC09B02)supported by the National Science and Technology Pillar Program during the 12th Five-Year Plan Period,China
文摘To make backfilling body meet strength requirement,physical-chemical evaluation and proportioning tests were conducted on several backfilling materials.Jigging sands,#32.5 cement and fly ash were determined as backfilling aggregate,binding material and modified material,respectively.An optimized proportion of backfilling materials with a solid mass fraction of 78%and cement:fly ash:jigging sands mass ratio of 1:2:14,was suggested to Jiangan Pyrite Mine,China.The slurry made by optimized proportion produced obvious shear thinning phenomena,and was confirmed as paste-like slurry.To analyze its rheological characteristics,L-type pipeline test and Haake VT550 rotational viscometer test were conducted.Bingham and Casson fluid models were applied to several paste-like slurry samples to simulate flow and stress states;Casson fluid model was proved to have better simulation effect on paste-like slurry with shear thinning phenomena;rheological parameters of backfilling slurry made by suggested proportion were measured.Initial yield stress,average apparent viscosity and limiting viscosity are 55.35 Pa,1.216 Pa-s and 0.48 Pa-s,respectively.Compared with Bingham fluid model,Casson fluid model has a better simulation effect on paste-like slurry with shear thinning phenomena,through calculating the residual standard deviations.
基金Project(2005Z023)supported by the Scientific Research Initial Funding of Chongqing University of Technology
文摘An Al2O3 protective coating on magnesium alloy AZ31 was prepared by a repeated direct sol-gel process annealing at 300℃and a composite coating was also deposited using Al2O3 particles dispersed sol followed by phosphating treatment and annealing at 300℃.The morphologies,structures and critical adhesive loads as well as corrosion properties of the coatings were comparatively investigated by scanning electron microscopy(SEM),X-ray diffractometry(XRD),nanoscratch test and electrochemical measurement.The results show that the composite coating has a more uniform,crack-free layer and improved adhesion to the substrate as compared with that of the repeated direct sol-gel coating owing to its lower heat strain.The main phases in both coatings consist ofγ-Al2O3 andδ-Al2O3 derived from annealed alumina sol,and the composite coating has an anticorrosion performance which is superior to that of the repeated direct sol-gel coating.
基金supported by the National Basic Research Program of China("973"Program)(Grant No.2009CB623200)the Airport Building Research Program of Jiangsu Province China(Grant No.LKJC-11-KY-001)the Research and Application Program of China’s Ministry of Railways(Grant No.2010g004-h)
文摘In order to determine the effects of different mineral admixtures including fly ash （FA）, blast furnace slag （BFS） and metakaolin （MK） on hydration product phases from the nanoscale structure perspective, nanoindentation characteristics of the samples with similar 28-day strengths have been investigated. The results indicate that the volume fractions of porosity in po- rosity and hydration product phases of the samples with the same kind of mineral admixture are almost equal to each other, and are greater than that of the sample without mineral admixture. Mineral admixtures especially MK can decrease remarkably the volume fractions of CH in porosity and hydration product phases, and there exists a good linear relationship between the （AI＋Si）/Ca molar ratio of cementitious materials chemical compositions and the volume fraction of HD C-S-H gel in C-S-H gel. Therefore, it is possible to predict the volume fraction change of HD C-S-H gel in C-S-H gel by simply calculating the （AI＋Si）/Ca molar ratio of cementitious materials with similar 28-day strengths under the constant water-binder ratio.
基金supported by the National Natural Science Foundation of China (61271353 and 60908033)the Natural Science Foundation of Anhui Province (1408085MKL47)
文摘Bioaerosol, an important constituent of the atmosphere, can directly affect light radiation characteristics due to absorption and scattering effects. Current research lacks a reasonable explanation for the extinction abilities of bioaerosols in a broadband. Herein, we measured the reflectance spectra of 12 com m on biomaterials and calculated their complex refractive indexes. The peaks of the imaginary part of the complex refractive indexes are located at wavelengths of approximately 0.7, 2.7, 6.1 and 9.5μm. Based on photographs of the floating structures of bioaerosols, we constructed a model for calculating the extinction abilities of bioaerosols in the wavelength range of 240 nm to 14 (im. Taking AN02 spores as an example, absorption was found to account for more than 90% of the total extinction. In addition, the theoretical calculations and experimental data of transmittance corresponding to the smoke box show that bioaerosol exhibits significant broadband extinction ability from UV to IR bands, which provides new directions for the development of broadband light attenuation materials.
