Calcium sulphoaluminate was prepared with chemical reagents in this paper. The formation mechanism of calcium sulphoaluminate and effect of CuO on the formation mechanism of calcium sulphoaluminate were investigated b...Calcium sulphoaluminate was prepared with chemical reagents in this paper. The formation mechanism of calcium sulphoaluminate and effect of CuO on the formation mechanism of calcium sulphoaluminate were investigated by the chemical analysis, X-ray diffraction （XRD）, and differential scanning calorimetry （DSC）. The results show that there are three ways in the formation of calcium sulphoaluminate. CuO can promote the decomposition of calcium carbonate and decrease the formation temperature of calcium sulphoaluminate（C4A3S）. When the burning temperature is below 1 000 ℃, the addition of CuO can promote the formation of calcium sulphoaluminate, while CuO can not favor the formation of calcium sulphoaluminate above 1 000 ℃.展开更多
The formation process of calcium suphoaluminate（C4A3S） was investigated by the X-ray diffraction technique and then the thermodynamics was analyzed, finally the kinetics of which was studied by SC-132. XRD results s...The formation process of calcium suphoaluminate（C4A3S） was investigated by the X-ray diffraction technique and then the thermodynamics was analyzed, finally the kinetics of which was studied by SC-132. XRD results show that the formation of C4A3S is accomplished in three different kinds of ways： one is by solid reaction of Ca （OH）2/ CaO, Al2O3 and CaSO4, other two ways are through such interstitial products as CaO·Al2O3 and CaO·2Al2O3. The formation thermodynamics shows that C4A3S begins to form at 900 ℃-1 000 ℃ and increases as temperature rising; the quantity of reaches the highest at 1 300 ℃-1 350 ℃ and then falls at 〉1350℃. Kinetics study shows that the formation rate of C4A3S can be described as first-order kinetics at high temperature, and it belongs to the random nucleation growth mechanism. The apparent activation energy is 456.37 kJ·mol-1 and pre-exponential factor is 1.545×1012.展开更多
The durability of the cement was mainly studied. Under 1.0 MPa of hydraulic pressure for 8 hours, water could penetrate completely through the sample made by portland cement, but could not penetrate through that by al...The durability of the cement was mainly studied. Under 1.0 MPa of hydraulic pressure for 8 hours, water could penetrate completely through the sample made by portland cement, but could not penetrate through that by alite-barium sulphoaluminate cement. Under the condition of freezing and thawing cycle, the loss ratio of compressive strength of the cement was only about 17.3% at curing 28 d ages, but the loss of portland cement was as high as 29.5%. Alite-calcium barium sulphoaluminate cement also has an excellent resistance to sulfate attack. The coefficients of resistance to sulfate attack of the cement exceeded 1.0. Meanwhile, the composition and microstructure of the hardened paste of alite-calcium barium sulphoaluminate cement were analyzed by XRD and SEM.展开更多
Formation and coexistence of tricalciurn silicate （C3S） and calcium sulphoaluminate （ C4 A3S^- ） minerals in Portland cement clinker containing calcium sulphoaluminate were investigated. Thef-CaO content, mineral ...Formation and coexistence of tricalciurn silicate （C3S） and calcium sulphoaluminate （ C4 A3S^- ） minerals in Portland cement clinker containing calcium sulphoaluminate were investigated. Thef-CaO content, mineral composite and formation of mineral in the clinker were analyzed respectively by chemical analysis, differential scanning calorimetry（DSC） and X-ray diffraction. The results show that, adding a suitable amount of BaO can improve the burnability of raw meal and promote the f-CaO absorption. Tricalcium silicate and calcium sulphoaluminate minerals can form and coexist in clinkers at 1 234-1 317 ℃ by the addition of BaO to the raw meal. A suitable amount of BaO expanded the coexistence temperature of two minerals by 58 ℃.展开更多
Calcium sulphoaluminate(3CaO·3Al2O3·CaSO4,abbreviated as C4A3S)was synthesized by sintering at1375°C for2h with analytically pure carbonate calcium,alumina and dihydrate calcium sulfate.The crystal stru...Calcium sulphoaluminate(3CaO·3Al2O3·CaSO4,abbreviated as C4A3S)was synthesized by sintering at1375°C for2h with analytically pure carbonate calcium,alumina and dihydrate calcium sulfate.The crystal structure of C4A3S was characterized by XRD,SEM and TEM.Alumina leaching properties in Na2CO3solution were studied,and the leaching mechanism was investigated by means of Raman spectrum and XRD.The results show that C4A3S has porous morphology.The polycrystallines and single crystals coexist in C4A3S and grow along different directions.The alumina leaching rate of C4A3S is98.41%,which is higher than that of12CaO·7Al2O3under the optimal condition.The aluminum and sulfur elements exist in the leaching solution in the form of Al(OH)4and24SO,respectively,and the calcium exists as CaCO3in the leaching residues.展开更多
As a 3D micro-nano material, layered double hydroxides have been widely used in many fields, especially for reinforced composite materials. In this paper, Li Al-LDHs was obtained by a hydrothermal method. In order to ...As a 3D micro-nano material, layered double hydroxides have been widely used in many fields, especially for reinforced composite materials. In this paper, Li Al-LDHs was obtained by a hydrothermal method. In order to investigate the effects of Li Al-LDHs on the early hydration of calcium sulphoaluminate（CSA） cement paste, compressive strength, setting time and hydration heat were tested while X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FT-IR）, scaning electron microscopy（SEM） and differential scanning calorimetry（DSC） analysis were employed. The results indicated that Li Al-LDHs could significantly improve the early compressive strength and shorten the setting time of calcium sulphoaluminate cement paste with 3 wt% concentration. Besides, the hydration exothermic rate within 5h was accelerated with increasing Li Al-LDHs content. Moreover, the addition of Li Al-LDHs did not result in the formation of a new phase, but increased the quantity of hydration products providing higher compressive strength, shorter setting time and denser microstructure.展开更多
采用工业原料配料,对以硅酸三钙(C_3S, C =CaO,S =SiO_2)、硫铝酸钙(C_4A_3, C =CaO,A=Al_2O_3,=SO_4^(2-))为主导矿物的含C_4A_3S矿物硅酸盐水泥熟料的矿物形成及其强度进行了研究。借助X射线衍射和热重差热分析研究了矿物形成过程...采用工业原料配料,对以硅酸三钙(C_3S, C =CaO,S =SiO_2)、硫铝酸钙(C_4A_3, C =CaO,A=Al_2O_3,=SO_4^(2-))为主导矿物的含C_4A_3S矿物硅酸盐水泥熟料的矿物形成及其强度进行了研究。借助X射线衍射和热重差热分析研究了矿物形成过程;探讨了微量元素ZnO对熟料性能的影响及在熟料体系中的固溶情况。研究结果表明:生料中掺入ZnO可使C_4A_3和C_3s等矿物通过低温反应形成,共存于同一熟料体系中,并可提高熟料的强度;过高的ZnO含量亦会降低C_4A_3矿物的分解温度。展开更多
基金the National High Technology Research and Development Program(No.2001CB610701)Nanjing Institute of Technology Innovation Foundation for Distinguished Ph D Candidate(No.BSCX200602)
文摘Calcium sulphoaluminate was prepared with chemical reagents in this paper. The formation mechanism of calcium sulphoaluminate and effect of CuO on the formation mechanism of calcium sulphoaluminate were investigated by the chemical analysis, X-ray diffraction （XRD）, and differential scanning calorimetry （DSC）. The results show that there are three ways in the formation of calcium sulphoaluminate. CuO can promote the decomposition of calcium carbonate and decrease the formation temperature of calcium sulphoaluminate（C4A3S）. When the burning temperature is below 1 000 ℃, the addition of CuO can promote the formation of calcium sulphoaluminate, while CuO can not favor the formation of calcium sulphoaluminate above 1 000 ℃.
基金Founded by the National Natural Science Foundation of China(50972116)
文摘The formation process of calcium suphoaluminate（C4A3S） was investigated by the X-ray diffraction technique and then the thermodynamics was analyzed, finally the kinetics of which was studied by SC-132. XRD results show that the formation of C4A3S is accomplished in three different kinds of ways： one is by solid reaction of Ca （OH）2/ CaO, Al2O3 and CaSO4, other two ways are through such interstitial products as CaO·Al2O3 and CaO·2Al2O3. The formation thermodynamics shows that C4A3S begins to form at 900 ℃-1 000 ℃ and increases as temperature rising; the quantity of reaches the highest at 1 300 ℃-1 350 ℃ and then falls at 〉1350℃. Kinetics study shows that the formation rate of C4A3S can be described as first-order kinetics at high temperature, and it belongs to the random nucleation growth mechanism. The apparent activation energy is 456.37 kJ·mol-1 and pre-exponential factor is 1.545×1012.
基金Funded by the National Natural Science Foundation of China (No.50672033)the "973"National Key Fundamental Research Plan ofChina (No.2009CB623101-1)
文摘The durability of the cement was mainly studied. Under 1.0 MPa of hydraulic pressure for 8 hours, water could penetrate completely through the sample made by portland cement, but could not penetrate through that by alite-barium sulphoaluminate cement. Under the condition of freezing and thawing cycle, the loss ratio of compressive strength of the cement was only about 17.3% at curing 28 d ages, but the loss of portland cement was as high as 29.5%. Alite-calcium barium sulphoaluminate cement also has an excellent resistance to sulfate attack. The coefficients of resistance to sulfate attack of the cement exceeded 1.0. Meanwhile, the composition and microstructure of the hardened paste of alite-calcium barium sulphoaluminate cement were analyzed by XRD and SEM.
基金Funded by the National Basic Research Program of China (No.2009CB623100)National Eleven Five-Year Scientific and Technical Support Plans (No. 2006BAF02A24)+2 种基金the Natural Science Fund for Colleges and Universities in Jiangsu Province(No. 08KJB430006)the Open Fund for the Key Laboratory of Inorganical and Composite Materials in Jiangsu Province(No.wjjqfhxc1200801)the Innovation Fund of Doctoral Dissertation of Nanjing University of Technology (No. BSCX200705)
文摘Formation and coexistence of tricalciurn silicate （C3S） and calcium sulphoaluminate （ C4 A3S^- ） minerals in Portland cement clinker containing calcium sulphoaluminate were investigated. Thef-CaO content, mineral composite and formation of mineral in the clinker were analyzed respectively by chemical analysis, differential scanning calorimetry（DSC） and X-ray diffraction. The results show that, adding a suitable amount of BaO can improve the burnability of raw meal and promote the f-CaO absorption. Tricalcium silicate and calcium sulphoaluminate minerals can form and coexist in clinkers at 1 234-1 317 ℃ by the addition of BaO to the raw meal. A suitable amount of BaO expanded the coexistence temperature of two minerals by 58 ℃.
基金Project (E2016208107) supported by the Natural Science Foundation of Hebei Province,ChinaProjects (QN2015002,BJ2016023) supported by the Science and Technology Foundation of Higher Education Institution of Hebei Province,China
文摘Calcium sulphoaluminate(3CaO·3Al2O3·CaSO4,abbreviated as C4A3S)was synthesized by sintering at1375°C for2h with analytically pure carbonate calcium,alumina and dihydrate calcium sulfate.The crystal structure of C4A3S was characterized by XRD,SEM and TEM.Alumina leaching properties in Na2CO3solution were studied,and the leaching mechanism was investigated by means of Raman spectrum and XRD.The results show that C4A3S has porous morphology.The polycrystallines and single crystals coexist in C4A3S and grow along different directions.The alumina leaching rate of C4A3S is98.41%,which is higher than that of12CaO·7Al2O3under the optimal condition.The aluminum and sulfur elements exist in the leaching solution in the form of Al(OH)4and24SO,respectively,and the calcium exists as CaCO3in the leaching residues.
基金Funded by the National Natural Sciense Foundation of China(No.51272068)
文摘As a 3D micro-nano material, layered double hydroxides have been widely used in many fields, especially for reinforced composite materials. In this paper, Li Al-LDHs was obtained by a hydrothermal method. In order to investigate the effects of Li Al-LDHs on the early hydration of calcium sulphoaluminate（CSA） cement paste, compressive strength, setting time and hydration heat were tested while X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FT-IR）, scaning electron microscopy（SEM） and differential scanning calorimetry（DSC） analysis were employed. The results indicated that Li Al-LDHs could significantly improve the early compressive strength and shorten the setting time of calcium sulphoaluminate cement paste with 3 wt% concentration. Besides, the hydration exothermic rate within 5h was accelerated with increasing Li Al-LDHs content. Moreover, the addition of Li Al-LDHs did not result in the formation of a new phase, but increased the quantity of hydration products providing higher compressive strength, shorter setting time and denser microstructure.
文摘采用工业原料配料,对以硅酸三钙(C_3S, C =CaO,S =SiO_2)、硫铝酸钙(C_4A_3, C =CaO,A=Al_2O_3,=SO_4^(2-))为主导矿物的含C_4A_3S矿物硅酸盐水泥熟料的矿物形成及其强度进行了研究。借助X射线衍射和热重差热分析研究了矿物形成过程;探讨了微量元素ZnO对熟料性能的影响及在熟料体系中的固溶情况。研究结果表明:生料中掺入ZnO可使C_4A_3和C_3s等矿物通过低温反应形成,共存于同一熟料体系中,并可提高熟料的强度;过高的ZnO含量亦会降低C_4A_3矿物的分解温度。
