The activities of municipal solid waste incineration （MSWI） fly ash and incineration residues were studied contrastively, through the component analysis and the activity ratio tests. The mechanical properties, hydra...The activities of municipal solid waste incineration （MSWI） fly ash and incineration residues were studied contrastively, through the component analysis and the activity ratio tests. The mechanical properties, hydration mechanism and leaching toxicity of the hardened cement paste mixing with MSWI fly ash and incineration residues were investigated. The experimental results indicated that the active constituents （CaO＋Al2O3＋Fe2O3） in MSWI fly ash were higher than those in incineration residues. Therefore the activity ratio of MSWI fly ash was 43.58%, twice as much as that of incineration residues. Meanwhile, the hydration of cement was delayed by mixing with MSWI fly ash and incineration residues, which also reduced the cement strength markedly. By adding with exceeding 20% MSWI fly ash, the specimens expanded and microcracks appeared. The leaching toxicities of cement pasted mixed with MSWI fly ash and incineration residues were lower than the Chinese national standard. Accordingly the cement mixed by MSWI fly ash and incineration residues can be considered as the environment-friendly materials.展开更多
To provide basic data for the reasonable mixing design of the alkali-activated (AA) foamed concrete as a thermal insulation material for a floor heating system, 9 concrete mixes with a targeted dry density less than 4...To provide basic data for the reasonable mixing design of the alkali-activated (AA) foamed concrete as a thermal insulation material for a floor heating system, 9 concrete mixes with a targeted dry density less than 400 kg/m3 were tested. Ground granulated blast-furnace slag (GGBS) as a source material was activated by the following two types of alkali activators: 10% Ca(OH)2 and 4% Mg(NO3)2, and 2.5% Ca(OH)2 and 6.5% Na2SiO3. The main test parameters were water-to-binder (W/B) ratio and the substitution level (RFA) of fly ash (FA) for GGBS. Test results revealed that the dry density of AA GGBS foamed concrete was independent of the W/B ratio an RFA, whereas the compressive strength increased with the decrease in W/B ratio and with the increase in RFA up to 15%, beyond which it decreased. With the increase in the W/B ratio, the amount of macro capillaries and artificial air pores increased, which resulted in the decrease of compressive strength. The magnitude of the environmental loads of the AA GGBS foamed concrete is independent of the W/B ratio and RFA. The largest reduction percentage was found in the photochemical oxidation potential, being more than 99%. The reduction percentage was 87% - 93% for the global warming potential, 81% - 84% for abiotic depletion, 79% - 84% for acidification potential, 77% - 85% for eutrophication potential, and 73% - 83% for human toxicity potential. Ultimately, this study proved that the developed AA GGBS foamed concrete has a considerable promise as a sustainable construction material for nonstructural element.展开更多
In order to improve the activity and eliminate some impurities, pretreatment wasused before hydrothermal synthesis. The fly ash was mixed with an aqueous NaOH solution, the alkali melted fly ash was also adopted, whic...In order to improve the activity and eliminate some impurities, pretreatment wasused before hydrothermal synthesis. The fly ash was mixed with an aqueous NaOH solution, the alkali melted fly ash was also adopted, which is hydrothermally treated at about104^(。)C, and the liquid/solid ratio was controlled at 6:1. In order to control Si/AI molar ratio,SiO_2 or AI_2O_3 powers were added to the fly ash. The results of XRD and SEM show thatthe alkali melted can activate fly ash and eliminate its quartz and mullite, along with theimprovement of Si/AI molar ratio and alkalinity. In addition, zeolite Na-A changes into sodalite gradually, and nepheline is the synthesized intermediate product. Those resultswere discussed on the basis of a formation mechanism of zeolite from fly ash.展开更多
In this paper, a high calcium high sulfate ash as the main material, adding fly ash, lime, cement, gypsum and some modifiers to prepare autoclaved aerated concrete. The products complies with the technical requirement...In this paper, a high calcium high sulfate ash as the main material, adding fly ash, lime, cement, gypsum and some modifiers to prepare autoclaved aerated concrete. The products complies with the technical requirements of GB/T11968-2006. This paper also studies the influence of the physical methods and water ratio on autoclaved aerated concrete by high calcium high sulfate ash aerated concrete. The best ratio of water and Grinding time were found in practice study.展开更多
Recycling of industrial waste is one of the effective ways to overcome their disposal problem. Ash produced by thermal power plants and lime sludge produced by paper mills require huge disposal land and may create env...Recycling of industrial waste is one of the effective ways to overcome their disposal problem. Ash produced by thermal power plants and lime sludge produced by paper mills require huge disposal land and may create environmental problems such as dusting and leaching of harmful heavy metals. Stabilization of the ash can improve its engineering properties and address the environmental problems. This paper reports the laboratory test results of a Class F pond ash stabilized with lime(2%, 4%, 6% and 8% by weight)alone and in combination with lime sludge(5%, 10% and 15% by weight). The X-ray diffraction(XRD) and scanning electron micrograph(SEM) tests were also performed to identify the possible formation of crystalline phases after stabilization. The effects of lime sludge on the unsoaked and soaked bearing ratios of pond ash with different lime contents, after 7 d, 28 d and 45 d of curing, were observed. Test results indicated that the bearing ratio increased considerably up to a 4% lime content which can be taken as the optimum lime content. Further increase in lime content increased bearing ratio gradually but at a slower rate. The effect of lime sludge was more pronounced at the optimum lime content,particularly at a low curing period. Lime sludge improved the bearing ratio in soaked condition significantly. Leachate analysis of stabilized ash was performed using toxicity characteristic leaching procedure(TCLP-1311) method. The concentrations of toxic elements Zn, Cu, Cd, Ni and Cr in the stabilized mixes were lower than those in the unstabilized waste. The results indicated that the pond ash-lime-lime sludge mixes have potential application as road subbase material.展开更多
基金Funded by the Major State Basic Research and Development Program ofChina ("973" Program) (No.2009CB623201)
文摘The activities of municipal solid waste incineration （MSWI） fly ash and incineration residues were studied contrastively, through the component analysis and the activity ratio tests. The mechanical properties, hydration mechanism and leaching toxicity of the hardened cement paste mixing with MSWI fly ash and incineration residues were investigated. The experimental results indicated that the active constituents （CaO＋Al2O3＋Fe2O3） in MSWI fly ash were higher than those in incineration residues. Therefore the activity ratio of MSWI fly ash was 43.58%, twice as much as that of incineration residues. Meanwhile, the hydration of cement was delayed by mixing with MSWI fly ash and incineration residues, which also reduced the cement strength markedly. By adding with exceeding 20% MSWI fly ash, the specimens expanded and microcracks appeared. The leaching toxicities of cement pasted mixed with MSWI fly ash and incineration residues were lower than the Chinese national standard. Accordingly the cement mixed by MSWI fly ash and incineration residues can be considered as the environment-friendly materials.
文摘To provide basic data for the reasonable mixing design of the alkali-activated (AA) foamed concrete as a thermal insulation material for a floor heating system, 9 concrete mixes with a targeted dry density less than 400 kg/m3 were tested. Ground granulated blast-furnace slag (GGBS) as a source material was activated by the following two types of alkali activators: 10% Ca(OH)2 and 4% Mg(NO3)2, and 2.5% Ca(OH)2 and 6.5% Na2SiO3. The main test parameters were water-to-binder (W/B) ratio and the substitution level (RFA) of fly ash (FA) for GGBS. Test results revealed that the dry density of AA GGBS foamed concrete was independent of the W/B ratio an RFA, whereas the compressive strength increased with the decrease in W/B ratio and with the increase in RFA up to 15%, beyond which it decreased. With the increase in the W/B ratio, the amount of macro capillaries and artificial air pores increased, which resulted in the decrease of compressive strength. The magnitude of the environmental loads of the AA GGBS foamed concrete is independent of the W/B ratio and RFA. The largest reduction percentage was found in the photochemical oxidation potential, being more than 99%. The reduction percentage was 87% - 93% for the global warming potential, 81% - 84% for abiotic depletion, 79% - 84% for acidification potential, 77% - 85% for eutrophication potential, and 73% - 83% for human toxicity potential. Ultimately, this study proved that the developed AA GGBS foamed concrete has a considerable promise as a sustainable construction material for nonstructural element.
基金Supported by the Henan Outstanding Youth Science Fund (0612002400)
文摘In order to improve the activity and eliminate some impurities, pretreatment wasused before hydrothermal synthesis. The fly ash was mixed with an aqueous NaOH solution, the alkali melted fly ash was also adopted, which is hydrothermally treated at about104^(。)C, and the liquid/solid ratio was controlled at 6:1. In order to control Si/AI molar ratio,SiO_2 or AI_2O_3 powers were added to the fly ash. The results of XRD and SEM show thatthe alkali melted can activate fly ash and eliminate its quartz and mullite, along with theimprovement of Si/AI molar ratio and alkalinity. In addition, zeolite Na-A changes into sodalite gradually, and nepheline is the synthesized intermediate product. Those resultswere discussed on the basis of a formation mechanism of zeolite from fly ash.
文摘In this paper, a high calcium high sulfate ash as the main material, adding fly ash, lime, cement, gypsum and some modifiers to prepare autoclaved aerated concrete. The products complies with the technical requirements of GB/T11968-2006. This paper also studies the influence of the physical methods and water ratio on autoclaved aerated concrete by high calcium high sulfate ash aerated concrete. The best ratio of water and Grinding time were found in practice study.
文摘Recycling of industrial waste is one of the effective ways to overcome their disposal problem. Ash produced by thermal power plants and lime sludge produced by paper mills require huge disposal land and may create environmental problems such as dusting and leaching of harmful heavy metals. Stabilization of the ash can improve its engineering properties and address the environmental problems. This paper reports the laboratory test results of a Class F pond ash stabilized with lime(2%, 4%, 6% and 8% by weight)alone and in combination with lime sludge(5%, 10% and 15% by weight). The X-ray diffraction(XRD) and scanning electron micrograph(SEM) tests were also performed to identify the possible formation of crystalline phases after stabilization. The effects of lime sludge on the unsoaked and soaked bearing ratios of pond ash with different lime contents, after 7 d, 28 d and 45 d of curing, were observed. Test results indicated that the bearing ratio increased considerably up to a 4% lime content which can be taken as the optimum lime content. Further increase in lime content increased bearing ratio gradually but at a slower rate. The effect of lime sludge was more pronounced at the optimum lime content,particularly at a low curing period. Lime sludge improved the bearing ratio in soaked condition significantly. Leachate analysis of stabilized ash was performed using toxicity characteristic leaching procedure(TCLP-1311) method. The concentrations of toxic elements Zn, Cu, Cd, Ni and Cr in the stabilized mixes were lower than those in the unstabilized waste. The results indicated that the pond ash-lime-lime sludge mixes have potential application as road subbase material.
