The primary objective of this research was to determine optimum dosage of mixing concrete containing plasticizers and fly ash, consistent with desirable structural grade concrete properties. Factorial tests were also ...The primary objective of this research was to determine optimum dosage of mixing concrete containing plasticizers and fly ash, consistent with desirable structural grade concrete properties. Factorial tests were also conducted to investigate the four main factors： water-cementing materials ratio, water content, content of superplasticizers （SP） and fly ash content. It was found that the requirement for setting time played the dominant role in shrinkage and anti-cracking, and fly ash played a critical role in workability and reducing heat of hydration but showed insignificant effects on slump, early strength and initial setting time of concrete.展开更多
In order to improve the convective heat transfer relating to an eddy current retarder,the finite element model has been used to assess the performances of different possible designs.In particular,assuming the steady r...In order to improve the convective heat transfer relating to an eddy current retarder,the finite element model has been used to assess the performances of different possible designs.In particular,assuming the steady running state of retarder as the working condition,flow and temperature fields have been obtained for the rotor.The influence of airflow path on heat dissipation has been analysed,and the influence of the temperature field distribution on the performance of retarder has been discussed accordingly.The results show that when the steady running state of the turntable is considered,the maximum temperature is lower,the level of turbulence flow is mitigated,and the temperature distribution becomes more regular.These factors contribute to improve the heat dissipation ability of the retarder.展开更多
We have shown that some phenylethynylsilicon compounds are good cure crosslinkersof heat-curable silicone rubber(HCSR). In this paper the effects of 1, 1, 3, 3-tetramethyl-1, 3-diphenylethynyldisiloxane (TMDPDS) as a ...We have shown that some phenylethynylsilicon compounds are good cure crosslinkersof heat-curable silicone rubber(HCSR). In this paper the effects of 1, 1, 3, 3-tetramethyl-1, 3-diphenylethynyldisiloxane (TMDPDS) as a crosslinker on HCSR were studied. Thevulcanizates with fine mechanical properties could be obtained with suitable amounts ofTMDPDS. Sol fractions, and crosslinking density of vulcanizates and vulcanizationretardation effect of TMDPDS on hydrosilation curing silicone rubber were also discussed.展开更多
The waste fluorgypsum was modified and applied as a cement retarder.The main chemical composition and mineral structure of the waste fluorgypsum were analyzed.Scanning electron microscopy (SEM) and eight-channel micro...The waste fluorgypsum was modified and applied as a cement retarder.The main chemical composition and mineral structure of the waste fluorgypsum were analyzed.Scanning electron microscopy (SEM) and eight-channel micro-calorimeter (TAM Air) were employed to analyze the changes in morphology and study the application performance of the modified fluorgypsum,respectively.Experimental results indicate that the flexural strength and compressive strength of the modified fluorgypsum are roughly equal to those of the natural gypsum.The morphology of the crystal of the fluorgypsum changes from block particle into trimetric short column.The fluorgypsum crystals stagger mutually and improve the strength of the hardened body.The modified fluorgypsum as cement retarder could delay the hydration,reduce the heat of the hydration and make the setting time,volume stability,and the SO3 content of the cement meet the national standards.The modified fluorgypsum is a good substitute for the natural gypsum.展开更多
基金Funded by the National Natural Science Foundation of China(51409202)the Fundamental Research Funds for the Central Universities(2013-IV-36)the Jiangxi Provincial Project of Science and Technology(20132GGB70107)
文摘The primary objective of this research was to determine optimum dosage of mixing concrete containing plasticizers and fly ash, consistent with desirable structural grade concrete properties. Factorial tests were also conducted to investigate the four main factors： water-cementing materials ratio, water content, content of superplasticizers （SP） and fly ash content. It was found that the requirement for setting time played the dominant role in shrinkage and anti-cracking, and fly ash played a critical role in workability and reducing heat of hydration but showed insignificant effects on slump, early strength and initial setting time of concrete.
基金supported by Scientific and Technological Research Program of Chongqing Municipal Education Commission(Grant No.KJ1603004).
文摘In order to improve the convective heat transfer relating to an eddy current retarder,the finite element model has been used to assess the performances of different possible designs.In particular,assuming the steady running state of retarder as the working condition,flow and temperature fields have been obtained for the rotor.The influence of airflow path on heat dissipation has been analysed,and the influence of the temperature field distribution on the performance of retarder has been discussed accordingly.The results show that when the steady running state of the turntable is considered,the maximum temperature is lower,the level of turbulence flow is mitigated,and the temperature distribution becomes more regular.These factors contribute to improve the heat dissipation ability of the retarder.
文摘We have shown that some phenylethynylsilicon compounds are good cure crosslinkersof heat-curable silicone rubber(HCSR). In this paper the effects of 1, 1, 3, 3-tetramethyl-1, 3-diphenylethynyldisiloxane (TMDPDS) as a crosslinker on HCSR were studied. Thevulcanizates with fine mechanical properties could be obtained with suitable amounts ofTMDPDS. Sol fractions, and crosslinking density of vulcanizates and vulcanizationretardation effect of TMDPDS on hydrosilation curing silicone rubber were also discussed.
基金Project(21003014) supported by the National Natural Science Foundation of ChinaProject(2010FJ3167) supported by the Hunan Provincial Science and Technology Program,ChinaProject(K1104029-11) supported by the Changsha IT Project
文摘The waste fluorgypsum was modified and applied as a cement retarder.The main chemical composition and mineral structure of the waste fluorgypsum were analyzed.Scanning electron microscopy (SEM) and eight-channel micro-calorimeter (TAM Air) were employed to analyze the changes in morphology and study the application performance of the modified fluorgypsum,respectively.Experimental results indicate that the flexural strength and compressive strength of the modified fluorgypsum are roughly equal to those of the natural gypsum.The morphology of the crystal of the fluorgypsum changes from block particle into trimetric short column.The fluorgypsum crystals stagger mutually and improve the strength of the hardened body.The modified fluorgypsum as cement retarder could delay the hydration,reduce the heat of the hydration and make the setting time,volume stability,and the SO3 content of the cement meet the national standards.The modified fluorgypsum is a good substitute for the natural gypsum.
