The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Cheng Xin - One of the best experts on this subject based on the ideXlab platform.
-
EFFECT OF MgO ON CALCINATION AND PROPERTIES OF BELITE-BARIUM Calcium Sulphoaluminate CEMENT CLINKER WITH Na₂O AND K₂O
University of Chemistry and Technology Prague, 2018Co-Authors: Wenyan Dai, Chenchen Gong, Lu Lingchao, Cheng XinAbstract:The High-quality limestone resources decreased sharply worldwide, and MgO-rich limestone, as an important part of low-quality limestone, is widely used in the cement production because of its low cost. The purpose of this study was to explore the effect of MgO (1-9 wt.%) on the composition and properties of belite-barium Calcium Sulphoaluminate cement with Na₂O and K₂O. The experimental results showed that 1∼3 wt.% of MgO in the mineral composition was in favor of calcining and stabilizing the crystal structure of M₃-C₃S, R-C₃S and β-C₂S in the cement clinker. Furthermore, the addition of MgO evidently increased the content of R-C₃S and β-C₂S and goes up to the highest value of 14.47% and22.4% when the addition of MgO reaches 7wt.%, and the increment of R-C₃S and β-C₂S was beneficial to improve the mechanical strength of the clinker. The 3d, 7d and 28d compressive strength of the cement with 7wt.% MgO increased by about 26%, 7.3% and 36.2% than that without MgO. Meanwhile, since the addition of MgO also can promote the formation of C₄AF, but has little effect on the formation of C2.75B1.25A₃$ and C₃A, the C₃A/C₄AF ratio present significantly reduction, which indicate that MgO can reduce the viscosity of the liquid phase in the process of calcination. So, the utilization of MgO in low-quality limestone has a great potential to develop low-carbon and sustainable society in producing the belite-barium Calcium Sulphoaluminate cement
-
effects of slag and limestone powder on the hydration and hardening process of alite barium Calcium Sulphoaluminate cement
Construction and Building Materials, 2012Co-Authors: Wang Shoude, Lu Lingchao, Chen Cheng, Cheng XinAbstract:Abstract For the existence of C 2.75 B 1.25 A 3 S ¯ mineral, alite-Calcium barium Sulphoaluminate cement has dual priming action of alkali-activated effect and sulfate-activated effect on mixed material. When the total amount of added mixed material is unchanged, the effects for ratio of slag to limestone powder on water requirement, setting time, mechanical performance, hydration products and hydration heat of alite-barium Calcium Sulphoaluminate cement are investigated. The experimental results show that the water requirement and setting time decrease with the decrease of the ratio of slag to limestone powder. The compressive strength of specimen cured for 90 days with 50% cement, 30% slag and 20% limestone powder is higher than that of pure cement. Slag and limestone powder prompt the second exothermic peak to appear early and shorten induction period. Furthermore, slag and limestone decrease rapidly hydration calorimetric of cement, especially for its early hydration calorimetric. Meanwhile, it is concluded that alite-Calcium barium Sulphoaluminate cement has dual priming action of alkali-activated effect and sulfate-activated effect.
-
study on the hydration of ba bearing Calcium Sulphoaluminate in the presence of gypsum
Cement and Concrete Research, 2004Co-Authors: Cheng Xin, Chang Jun, Lu Lingchao, Liu Futian, Teng BingAbstract:This article reports on a study of the hydration of Ba-bearing Sulphoaluminate in the presence of gypsum. In the study, a new series of Ba-bearing Calcium Sulphoaluminate minerals are synthesized by a different equivalent of Ba2+, replacing Ca2+ in the C4A3S. By means of XRD, IR, SEM, etc, the authors studied the hydration of minerals in the presence of a certain amount of gypsum. The hydrates are AFt, BaSO4, and Al(OH)3 gel. The authors explain the reasons for the early strength and rapid hardening of Ba-bearing Calcium Sulphoaluminate cement. From the beginning of the hydration of Ba-bearing Calcium Sulphoaluminate, BaSO4 is formed and filled in the hole, while Calcium aluminate reacts with gypsum to form Aft and Ah3 gel.
-
study of ba bearing Calcium Sulphoaluminate minerals and cement
Cement and Concrete Research, 2000Co-Authors: Cheng Xin, Chang Jun, Lu Lingchao, Liu Futian, Teng BingAbstract:Abstract In this paper, we synthesized a series of new cement minerals, Ba-bearing Calcium Sulphoaluminates, by the substitution of Ba2+ for Ca2+ ions of C4A3S (3CaO · 3Al2O3 · CaSO4). The strength development was studied. The results show that the strength of Ba-bearing Calcium Sulphoaluminates is higher than that of C4A3S, and the optimal composition has been found. Based on this conclusion, Ba-bearing Calcium sulphoaluminte cement has been burned with Ba-bearing industrial wastes. In addition, the hydration mechanism of the cement was analyzed by X-ray diffraction, scanning electron microscopy, and infrared spectrophotometry.
Teng Bing - One of the best experts on this subject based on the ideXlab platform.
-
study on the hydration of ba bearing Calcium Sulphoaluminate in the presence of gypsum
Cement and Concrete Research, 2004Co-Authors: Cheng Xin, Chang Jun, Lu Lingchao, Liu Futian, Teng BingAbstract:This article reports on a study of the hydration of Ba-bearing Sulphoaluminate in the presence of gypsum. In the study, a new series of Ba-bearing Calcium Sulphoaluminate minerals are synthesized by a different equivalent of Ba2+, replacing Ca2+ in the C4A3S. By means of XRD, IR, SEM, etc, the authors studied the hydration of minerals in the presence of a certain amount of gypsum. The hydrates are AFt, BaSO4, and Al(OH)3 gel. The authors explain the reasons for the early strength and rapid hardening of Ba-bearing Calcium Sulphoaluminate cement. From the beginning of the hydration of Ba-bearing Calcium Sulphoaluminate, BaSO4 is formed and filled in the hole, while Calcium aluminate reacts with gypsum to form Aft and Ah3 gel.
-
study of ba bearing Calcium Sulphoaluminate minerals and cement
Cement and Concrete Research, 2000Co-Authors: Cheng Xin, Chang Jun, Lu Lingchao, Liu Futian, Teng BingAbstract:Abstract In this paper, we synthesized a series of new cement minerals, Ba-bearing Calcium Sulphoaluminates, by the substitution of Ba2+ for Ca2+ ions of C4A3S (3CaO · 3Al2O3 · CaSO4). The strength development was studied. The results show that the strength of Ba-bearing Calcium Sulphoaluminates is higher than that of C4A3S, and the optimal composition has been found. Based on this conclusion, Ba-bearing Calcium sulphoaluminte cement has been burned with Ba-bearing industrial wastes. In addition, the hydration mechanism of the cement was analyzed by X-ray diffraction, scanning electron microscopy, and infrared spectrophotometry.
Lu Lingchao - One of the best experts on this subject based on the ideXlab platform.
-
EFFECT OF MgO ON CALCINATION AND PROPERTIES OF BELITE-BARIUM Calcium Sulphoaluminate CEMENT CLINKER WITH Na₂O AND K₂O
University of Chemistry and Technology Prague, 2018Co-Authors: Wenyan Dai, Chenchen Gong, Lu Lingchao, Cheng XinAbstract:The High-quality limestone resources decreased sharply worldwide, and MgO-rich limestone, as an important part of low-quality limestone, is widely used in the cement production because of its low cost. The purpose of this study was to explore the effect of MgO (1-9 wt.%) on the composition and properties of belite-barium Calcium Sulphoaluminate cement with Na₂O and K₂O. The experimental results showed that 1∼3 wt.% of MgO in the mineral composition was in favor of calcining and stabilizing the crystal structure of M₃-C₃S, R-C₃S and β-C₂S in the cement clinker. Furthermore, the addition of MgO evidently increased the content of R-C₃S and β-C₂S and goes up to the highest value of 14.47% and22.4% when the addition of MgO reaches 7wt.%, and the increment of R-C₃S and β-C₂S was beneficial to improve the mechanical strength of the clinker. The 3d, 7d and 28d compressive strength of the cement with 7wt.% MgO increased by about 26%, 7.3% and 36.2% than that without MgO. Meanwhile, since the addition of MgO also can promote the formation of C₄AF, but has little effect on the formation of C2.75B1.25A₃$ and C₃A, the C₃A/C₄AF ratio present significantly reduction, which indicate that MgO can reduce the viscosity of the liquid phase in the process of calcination. So, the utilization of MgO in low-quality limestone has a great potential to develop low-carbon and sustainable society in producing the belite-barium Calcium Sulphoaluminate cement
-
EFFECT OF MgO ON THE COMPOSITION AND PROPERTIES OF BELITE-BARIUM Calcium Sulphoaluminate CEMENT IN THE PRESENCE OF Na2O AND K2O
University of Chemistry and Technology Prague, 2015Co-Authors: Jie Zhang, Lu Lingchao, Chenchen Gong, Wang Shoude, Hou PengkunAbstract:The purpose of this study is to explore the effect of MgO (1 - 9 wt. %) on the composition and properties of belite-barium Calcium Sulphoaluminate cement with additions of Na2O and K2O. The results show that 1 - 5 wt. % content of MgO can stabilize crystal types of M3-C3S, R-C3S and β-C2S. Moreover, MgO can promote the formation of C3S and C4AF, but has little effect on the formation of C2.75B1.25A3$ and C3A. The C3A/C4AF ratio is reduced by 22 % at 5 wt. % MgO, which indicates that appropriate MgO can decrease the liquid viscosity. In the presence of Na2O and K2O, the highest limit of incorporated amount of MgO is about 3 wt. %, which is higher than that in Portland cement clinker of 2 wt. %. Besides, MgO favors the formation of small C3S crystals in size of 4 - 20 μm. MgO enhances the hydration rate and mechanical property of cement at an optimal dosage (1 - 5 wt. %), beyond which an adverse effect could be resulted. At a MgO dosage of 5 wt. %, the compressive strengths of the cement at 1, 3, 7 and 28 days are 15.8, 39.3, 68.6 and 97.3 MPa, which increases by 116 %, 17 %, 10 % and 6 % respectively compared to the cement without MgO dopant. This study could lead to the effective use of magnesia-rich limestone in industrial production of belite-barium Calcium Sulphoaluminate cement
-
effects of slag and limestone powder on the hydration and hardening process of alite barium Calcium Sulphoaluminate cement
Construction and Building Materials, 2012Co-Authors: Wang Shoude, Lu Lingchao, Chen Cheng, Cheng XinAbstract:Abstract For the existence of C 2.75 B 1.25 A 3 S ¯ mineral, alite-Calcium barium Sulphoaluminate cement has dual priming action of alkali-activated effect and sulfate-activated effect on mixed material. When the total amount of added mixed material is unchanged, the effects for ratio of slag to limestone powder on water requirement, setting time, mechanical performance, hydration products and hydration heat of alite-barium Calcium Sulphoaluminate cement are investigated. The experimental results show that the water requirement and setting time decrease with the decrease of the ratio of slag to limestone powder. The compressive strength of specimen cured for 90 days with 50% cement, 30% slag and 20% limestone powder is higher than that of pure cement. Slag and limestone powder prompt the second exothermic peak to appear early and shorten induction period. Furthermore, slag and limestone decrease rapidly hydration calorimetric of cement, especially for its early hydration calorimetric. Meanwhile, it is concluded that alite-Calcium barium Sulphoaluminate cement has dual priming action of alkali-activated effect and sulfate-activated effect.
-
study on the hydration of ba bearing Calcium Sulphoaluminate in the presence of gypsum
Cement and Concrete Research, 2004Co-Authors: Cheng Xin, Chang Jun, Lu Lingchao, Liu Futian, Teng BingAbstract:This article reports on a study of the hydration of Ba-bearing Sulphoaluminate in the presence of gypsum. In the study, a new series of Ba-bearing Calcium Sulphoaluminate minerals are synthesized by a different equivalent of Ba2+, replacing Ca2+ in the C4A3S. By means of XRD, IR, SEM, etc, the authors studied the hydration of minerals in the presence of a certain amount of gypsum. The hydrates are AFt, BaSO4, and Al(OH)3 gel. The authors explain the reasons for the early strength and rapid hardening of Ba-bearing Calcium Sulphoaluminate cement. From the beginning of the hydration of Ba-bearing Calcium Sulphoaluminate, BaSO4 is formed and filled in the hole, while Calcium aluminate reacts with gypsum to form Aft and Ah3 gel.
-
study of ba bearing Calcium Sulphoaluminate minerals and cement
Cement and Concrete Research, 2000Co-Authors: Cheng Xin, Chang Jun, Lu Lingchao, Liu Futian, Teng BingAbstract:Abstract In this paper, we synthesized a series of new cement minerals, Ba-bearing Calcium Sulphoaluminates, by the substitution of Ba2+ for Ca2+ ions of C4A3S (3CaO · 3Al2O3 · CaSO4). The strength development was studied. The results show that the strength of Ba-bearing Calcium Sulphoaluminates is higher than that of C4A3S, and the optimal composition has been found. Based on this conclusion, Ba-bearing Calcium sulphoaluminte cement has been burned with Ba-bearing industrial wastes. In addition, the hydration mechanism of the cement was analyzed by X-ray diffraction, scanning electron microscopy, and infrared spectrophotometry.
G.l. Valenti - One of the best experts on this subject based on the ideXlab platform.
-
Low-carbon Calcium Sulphoaluminate cements synthesized from industrial wastes and by-products
2012Co-Authors: A. Telesca, M. Marroccoli, M.l. Pace, G.l. ValentiAbstract:Compared to Portland cements, Calcium Sulphoaluminate (CSA) cements are energy saving and low-CO2 hydraulic binders, due to the decrease of synthesis temperature and kiln thermal input associated with the reduced limestone requirement and carbon dioxide generation. Further enhancements in terms of environmentally friendly features can be achieved if some industrial wastes are used as partial or total substitutes for the natural materials (limestone, bauxite, gypsum) involved in the CSA cement manufacture. This paper deals with a laboratory investigation of synthetic CSA clinkers generated in an electric oven at 1150°, 1200°, 1250° and 1300°C from raw mixtures containing (i) bottom ash derived from the fluidized bed combustion (FBC) of coal (essentially a source of noncarbonated lime and Calcium sulphate) and (ii) anodization mud (AM) or alumina powder (AP), Al2O3 rich by-products originated by the production of anodized aluminium elements and the secondary aluminium manufacture, respectively. Six bauxite-free ternary blends, containing 10-35% limestone plus 0-31% natural gypsum or 0-40% FBC bottom ash plus 0-69% AM or 0-50% AP, and four binary blends, consisting only of 37-60% FBC bottom ash and 52-63% AM or 40-45% AP, were explored. They were generally more suitable than a reference mixture composed by 42% bauxite, 33% gypsum and 25% limestone. XRD analysis showed a complete conversion of reactants and a very good selectivity towards C A S 4 3 , the main CSA cement component
-
use of fluidized bed combustion ash and other industrial wastes as raw materials for the manufacture of Calcium Sulphoaluminate cements
pot, 2009Co-Authors: M. Marroccoli, F. Montagnaro, A. Telesca, M.l. Pace, G.l. ValentiAbstract:Calcium Sulphoaluminate cements, mainly composed by 4CaO·3Al2O3·SO3 and 2CaO·SiO2, are special hydraulic binders which require limestone, bauxite and gypsum as natural raw materials for their manufacture. In order to save bauxite and natural gypsum, it has been explored the possibility of using, among the raw mix components, FBC waste together with pulverised coal fly ash or anodization mud and, when necessary, flue gas desulphurization gypsum. Mixtures containing limestone (29–39%), FBC waste (30–44%), pulverised coal fly ash (0–13%) or anodization mud (0–32%), bauxite (0–18%) and flue gas desulphurization gypsum (0–8%) were heated for 2 hours in a laboratory electric oven at temperatures ranging from 1150° to 1300°C. The X-ray diffraction patterns on the burnt products generally showed a good conversion of the reactants and a high selectivity degree towards 4CaO·3Al2O3·SO3, particularly at 1250°C.
-
Fluidized bed combustion waste as a raw mix component for the manufacture of Calcium Sulphoaluminate cements
2006Co-Authors: G. Belz, P. Caramuscio, M. Marroccoli, F. Montagnaro, M. Nobili, A. Telesca, G.l. ValentiAbstract:It has been found that raw mixes for the manufacture of Calcium Sulphoaluminate cements are able to contain not only fluidised bed combustion wastes, but also other by-products, such as fly ash and flue gas desulphurization waste, coming from a traditional coal-fired power station. The concentration of FBC waste was comprised between 10 and 20%; the overall concentration of the by-products ranged from 33 to 40%. Very satisfactory results were obtained in terms of conversion and selectivity towards the desired hydraulic compounds, Calcium Sulphoaluminate and diCalcium silicate, in the range of the temperatures investigated, 1200°-1300 °C. The best synthesis temperature for obtaining the maximum amount of both phases was about 1250°C
-
Synthesis of special cements from mixtures containing fluidized bed combustion waste, Calcium carbonate and various sources of alumina
2005Co-Authors: G. Belz, P. Caramuscio, A. Telesca, F. Montagnaro, G. Bernardo, G.l. ValentiAbstract:This paper is focused on the use of a CFBC (circulating fluidized bed combustion) fly ash as raw mix component for the synthesis of Calcium Sulphoaluminate cements. The raw mix composition was designed in order to combine all available sulphate and silica into Calcium Sulphoaluminate and diCalcium silicate, respectively. To this end additional sources of Calcium and aluminium oxides were required: the former was given by pure Calcium carbonate; the latter by pure alumina, red mud and/or bauxite
-
Use of fluidized bed combustion wastes for the synthesis of low-energy cements
2003Co-Authors: Graziella Bernardo, M. Marroccoli, F. Montagnaro, G.l. ValentiAbstract:Among the low-energy binders, Calcium Sulphoaluminate cements are worthy of consideration also because a wide range of industrial solid wastes can be utilized in their manufacture. In this paper, it has been proposed the use of mixtures composed by fluidized bed combustion wastes as raw materials for the synthesis of Calcium Sulphoaluminate cements. Several systems based on two fluidized bed combustion-derived wastes (a sulpho-calcic fly ash and a silico-aluminous fly ash) and a solid waste generated within a traditional coal-fired power plant were heated in a laboratory electric oven for 2 hours at temperatures ranging from 1050°C to 1300°C. Calcium Sulphoaluminate was often obtained and its formation was related to the waste nature and the burning temperature
Xiaodong Shen - One of the best experts on this subject based on the ideXlab platform.
-
effects of limestone powder on the hydration and microstructure development of Calcium Sulphoaluminate cement under long term curing
Construction and Building Materials, 2019Co-Authors: Hu Shi, Xiaodong ShenAbstract:Abstract In order to explore the effects of limestone powder on the long-term performance of Calcium Sulphoaluminate (CSA) cement, the hydration process and microstructure development of CSA cement incorporated with limestone powder are investigated at the ages from 1 day to 1 year. Three limestone powder dosages, such as 5%, 15% and 25% are considered. Three techniques, such as isothermal calorimetry, X-ray diffraction (XRD) and thermogravimetry (TG) were used to study the hydration process of cement pastes. Mercury intrusion porosimetry (MIP) was used to determine the pore structure of cement pastes. The results show that like in Portland cement, the addition of limestone powder in CSA cement can participate the reactions and form hemicarboaluminate phase. The difference is that monocarbonate phase is not found in the CSA-limestone powder binary system at the curing age from 1 day to 1 year. The addition of limestone powder can reduce the total porosity and critical pore size at 1 day. At long-term curing period, the critical pore size of CSA cement replaced by 5% limestone powder is almost equally to that of CSA cement.
-
the compressive strength of cement slag Calcium Sulphoaluminate ternary system
International Conference on the Durability of Concrete Structures, 2016Co-Authors: Hu Shi, Jun Wang, Xiaodong ShenAbstract:At present, there is an increasing interest on the use of Calcium Sulphoaluminate (C4A3$) in cement. In this paper, pure mineral of Sulphoaluminate (C4A3$) was prepared in laboratory. Different dosages of steel slag and C4A3$ were blended into cement. The aim of this paper is to investigate the compressive strength of this ternary system. The test results show that the addition of C4A3$ can improve the strength of cement. Larger C4A3$ dosage (7%) may reduce the 28 days strength. The optimal C4A3$ dosage is 5%. In ternary system, C4A3$ has no obvious improvement, while 5% dosage could improve the strength a little.
-
effect of barium oxide on the formation and coexistence of triCalcium silicate and Calcium Sulphoaluminate
Journal of Wuhan University of Technology-materials Science Edition, 2009Co-Authors: Lin Chen, Xiaodong Shen, Yeping Huang, Baiqian ZhongAbstract:Formation and coexistence of triCalcium silicate (C3S) and Calcium Sulphoaluminate (C4A3 $$ \bar S $$ ) minerals in Portland cement clinker containing Calcium Sulphoaluminate were investigated. The f-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 °C by the addition of BaO to the raw meal. A suitable amount of BaO expanded the coexistence temperature of two minerals by 58 °.
-
effect of cuo on the formation mechanism of Calcium Sulphoaluminate
Journal of Wuhan University of Technology-materials Science Edition, 2008Co-Authors: Xiaodong Shen, Yeping Huang, Baiqian ZhongAbstract: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 Open image in new window . When the burning temperature is below 1 000 °C, the addition of CuO can promote the formation of Calcium Sulphoaluminate, while CuO can not favor the formation of Calcium Sulphoaluminate above 1 000 °C.
