High calcium-fly ash(HCFA)collected from the Mae Moh electricity generating plant in Thailand was utilized as a raw material for ceramic production.The main compositions of HCFA characterized by X-ray fluorescence mai...High calcium-fly ash(HCFA)collected from the Mae Moh electricity generating plant in Thailand was utilized as a raw material for ceramic production.The main compositions of HCFA characterized by X-ray fluorescence mainly consisted of 28.55wt%SiO_(2),16.06wt%Al_(2)O_(3),23.40wt%CaO,and 17.03wt%Fe_(2)O_(3).Due to high proportion of calcareous and ferruginous contents,HCFA was used for replacing the potash feldspar in amounts of 10wt%-40wt%.The influence of substituting high-calcium fly ash(0-40wt%)and sintering temperatures(1000-1200℃)on physical,mechanical,and thermal properties of ceramic-based materials was investigated.The results showed that the in-corporation of HCFA in appropriate amounts could enhance the densification and the strength as well as reduce the thermal conductivity of ceramic samples.High proportion of calcareous and ferruginous constituents in fly ash promoted the vitrification behavior of ceramic samples.As a result,the densification was enhanced by liquid phase formation at optimum fly ash content and sintering temperature.In addition,these components also facilitated a more abundant mullite formation and consequently improved flexural strength of the ceramic samples.The op-timum ceramic properties were achieved with adding fly ash content between 10wt%-30wt%sintered at 1150-1200℃.At 1200℃,the max-imum flexural strength of ceramic-FA samples with adding fly ash 10wt%-30wt%(PSW-FA(10)-(30))was obtained in the range of 92.25-94.71 MPa when the water absorption reached almost zero(0.03%).In terms of thermal insulation materials,the increase in fly ash addi-tion had a positively effect on the thermal conductivity,due to the higher levels of porosity created by gas evolving from the inorganic decom-position reactions inside the ceramic-FA samples.The addition of 20wt%-40wt%high-calcium fly ash in ceramic samples sintered at 1150℃reduced the thermal conductivity to 14.78%-49.25%,while maintaining acceptable flexural strength values(~45.67-87.62 MPa).Based on these promising mechanical and thermal characteristics,it is feasible to utilize this high-calcium fly ash as an alternative raw material in clay compositions for manufacturing of ceramic tiles.展开更多
This work investigates durability of cement-free mortars with a binder comprised of ground granulated blast furnace slag (GGBFS) activated by high-calcium fly ash (HCFA) and sodium carbonate (Na<sub>2</sub>...This work investigates durability of cement-free mortars with a binder comprised of ground granulated blast furnace slag (GGBFS) activated by high-calcium fly ash (HCFA) and sodium carbonate (Na<sub>2</sub>CO<sub>3</sub>): the soundness, sulfate resistance, alkali-silica reactivity and efflorescence factors are considered. Results of tests show that such mortars are resistant to alkali-silica expansion. Mortars are also sulfate-resistant when the amount of HCFA in the complex binder is within a limit of 10 wt%. The fineness of fly ash determines its’ ability to activate GGBFS hydration, and influence soundness of the binder, early strength development, sulfate resistance and efflorescence behavior. The present article is a continuation of authors’ work, previously published in MSA, Vol. 14, 240-254.展开更多
High-calcium fly ash (HCFA)—a residue of high-temperature coal combustion at thermal power plants, in combination with sodium carbonate presents an effective hardening activator of ground granulated blast-furnace sla...High-calcium fly ash (HCFA)—a residue of high-temperature coal combustion at thermal power plants, in combination with sodium carbonate presents an effective hardening activator of ground granulated blast-furnace slag (GGBFS). Substitution of 10% - 30% of GGBFS by HCFA and premixing of 1% - 3% Na2CO3 to this dry binary binder was discovered to give mortar compression strength of 10 - 30 to 30 - 45 MPa at 7 and 28 days when moist cured at ambient temperature. High-calcium fly ash produced from low-temperature combustion of fuel, like in circulating fluidized bed technology, reacts with water readily and is itself a good hardening activator for GGBFS, so introduction of Na<sub>2</sub>CO<sub>3</sub> into such mix has no noticeable effect on the mortar strength. However, low-temperature HCFA has higher water demand, and the strength of mortar is compromised by this factor. As of today, our research is still ongoing, and we expect to publish more data on different aspects of durability of proposed GGBFS-HCFA binder later.展开更多
为了明确多因素耦合作用下低钙高强水泥混凝土的性能退化机理,本文通过设置不同侵蚀因素(冻融-溶蚀、冻融-Cl^(-)侵蚀、溶蚀-Cl^(-)侵蚀、冻融-溶蚀-Cl^(-)侵蚀),结合外观变化、质量变化、超声波速率、Cl^(-)含量、物相组成测试等,研究...为了明确多因素耦合作用下低钙高强水泥混凝土的性能退化机理,本文通过设置不同侵蚀因素(冻融-溶蚀、冻融-Cl^(-)侵蚀、溶蚀-Cl^(-)侵蚀、冻融-溶蚀-Cl^(-)侵蚀),结合外观变化、质量变化、超声波速率、Cl^(-)含量、物相组成测试等,研究了低钙原料高强熟料水泥(Low-calcium raw material and high-strength clinker cement,LCHS)混凝土的损伤演化规律。结果表明:在冻融-溶蚀-Cl^(-)侵蚀耦合作用下,LCHS混凝土历经早期质量提升、中期Ca^(2+)溶蚀与盐结晶的动态平衡以及后期损害快速发展的过程,溶蚀-Cl^(-)侵蚀作用在早期和中期会降低LCHS混凝土的损伤;冻融-Cl^(-)侵蚀和冻融-溶蚀对LCHS混凝土的损伤基本高于冻融-溶蚀-Cl^(-)侵蚀;LCHS混凝土的耐久性能优于普通硅酸盐水泥混凝土。研究结果可以为寒冷地区、地下水或除冰盐环境下低钙高强水泥混凝土结构的设计、耐久性能评估及寿命预测提供参考。展开更多
基金This work was financially supported by the National Metal and Materials Technology Center,Thailand(Project No.P-18-50327).
文摘High calcium-fly ash(HCFA)collected from the Mae Moh electricity generating plant in Thailand was utilized as a raw material for ceramic production.The main compositions of HCFA characterized by X-ray fluorescence mainly consisted of 28.55wt%SiO_(2),16.06wt%Al_(2)O_(3),23.40wt%CaO,and 17.03wt%Fe_(2)O_(3).Due to high proportion of calcareous and ferruginous contents,HCFA was used for replacing the potash feldspar in amounts of 10wt%-40wt%.The influence of substituting high-calcium fly ash(0-40wt%)and sintering temperatures(1000-1200℃)on physical,mechanical,and thermal properties of ceramic-based materials was investigated.The results showed that the in-corporation of HCFA in appropriate amounts could enhance the densification and the strength as well as reduce the thermal conductivity of ceramic samples.High proportion of calcareous and ferruginous constituents in fly ash promoted the vitrification behavior of ceramic samples.As a result,the densification was enhanced by liquid phase formation at optimum fly ash content and sintering temperature.In addition,these components also facilitated a more abundant mullite formation and consequently improved flexural strength of the ceramic samples.The op-timum ceramic properties were achieved with adding fly ash content between 10wt%-30wt%sintered at 1150-1200℃.At 1200℃,the max-imum flexural strength of ceramic-FA samples with adding fly ash 10wt%-30wt%(PSW-FA(10)-(30))was obtained in the range of 92.25-94.71 MPa when the water absorption reached almost zero(0.03%).In terms of thermal insulation materials,the increase in fly ash addi-tion had a positively effect on the thermal conductivity,due to the higher levels of porosity created by gas evolving from the inorganic decom-position reactions inside the ceramic-FA samples.The addition of 20wt%-40wt%high-calcium fly ash in ceramic samples sintered at 1150℃reduced the thermal conductivity to 14.78%-49.25%,while maintaining acceptable flexural strength values(~45.67-87.62 MPa).Based on these promising mechanical and thermal characteristics,it is feasible to utilize this high-calcium fly ash as an alternative raw material in clay compositions for manufacturing of ceramic tiles.
文摘This work investigates durability of cement-free mortars with a binder comprised of ground granulated blast furnace slag (GGBFS) activated by high-calcium fly ash (HCFA) and sodium carbonate (Na<sub>2</sub>CO<sub>3</sub>): the soundness, sulfate resistance, alkali-silica reactivity and efflorescence factors are considered. Results of tests show that such mortars are resistant to alkali-silica expansion. Mortars are also sulfate-resistant when the amount of HCFA in the complex binder is within a limit of 10 wt%. The fineness of fly ash determines its’ ability to activate GGBFS hydration, and influence soundness of the binder, early strength development, sulfate resistance and efflorescence behavior. The present article is a continuation of authors’ work, previously published in MSA, Vol. 14, 240-254.
文摘High-calcium fly ash (HCFA)—a residue of high-temperature coal combustion at thermal power plants, in combination with sodium carbonate presents an effective hardening activator of ground granulated blast-furnace slag (GGBFS). Substitution of 10% - 30% of GGBFS by HCFA and premixing of 1% - 3% Na2CO3 to this dry binary binder was discovered to give mortar compression strength of 10 - 30 to 30 - 45 MPa at 7 and 28 days when moist cured at ambient temperature. High-calcium fly ash produced from low-temperature combustion of fuel, like in circulating fluidized bed technology, reacts with water readily and is itself a good hardening activator for GGBFS, so introduction of Na<sub>2</sub>CO<sub>3</sub> into such mix has no noticeable effect on the mortar strength. However, low-temperature HCFA has higher water demand, and the strength of mortar is compromised by this factor. As of today, our research is still ongoing, and we expect to publish more data on different aspects of durability of proposed GGBFS-HCFA binder later.
文摘为了明确多因素耦合作用下低钙高强水泥混凝土的性能退化机理,本文通过设置不同侵蚀因素(冻融-溶蚀、冻融-Cl^(-)侵蚀、溶蚀-Cl^(-)侵蚀、冻融-溶蚀-Cl^(-)侵蚀),结合外观变化、质量变化、超声波速率、Cl^(-)含量、物相组成测试等,研究了低钙原料高强熟料水泥(Low-calcium raw material and high-strength clinker cement,LCHS)混凝土的损伤演化规律。结果表明:在冻融-溶蚀-Cl^(-)侵蚀耦合作用下,LCHS混凝土历经早期质量提升、中期Ca^(2+)溶蚀与盐结晶的动态平衡以及后期损害快速发展的过程,溶蚀-Cl^(-)侵蚀作用在早期和中期会降低LCHS混凝土的损伤;冻融-Cl^(-)侵蚀和冻融-溶蚀对LCHS混凝土的损伤基本高于冻融-溶蚀-Cl^(-)侵蚀;LCHS混凝土的耐久性能优于普通硅酸盐水泥混凝土。研究结果可以为寒冷地区、地下水或除冰盐环境下低钙高强水泥混凝土结构的设计、耐久性能评估及寿命预测提供参考。
