Management of incinerated sewage sludge ash(ISSA)and dredged contaminated marine sediments(CMSs)is a great challenge for Hong Kong and other coastal cities due to limited landfilling capacity.The present study investi...Management of incinerated sewage sludge ash(ISSA)and dredged contaminated marine sediments(CMSs)is a great challenge for Hong Kong and other coastal cities due to limited landfilling capacity.The present study investigates the use of high content(20%of sediment by mass)of ISSA in combination with cement/lime for solidification/stabilization(S/S)treatment of CMSs to provide a way to reuse the wastes as construction materials.The results showed that ISSA being a porous material was able to absorb a large amount of water rendering a more efficient solidification process of the marine sediment which normally had a very high water content(w80%).The S/S treatment improved the engineering properties of the sediment,but reduced the workability,especially for the lime-treated samples.Lime can be used to replace ordinary Portland cement(OPC)for better heavy metal immobilization and carbon emission reduction.The hardened sediment samples prepared with 10%of lime and 20%of ISSA could attain a strength of 1.6 MPa after 28 d of curing.In addition,leaching tests confirmed that there was no environmental risk induced by these stabilized materials.The formation of hydrated cementitious compounds including calcium silicate hydrate(CeSeH)/calcium aluminate silicate hydrate(C-A-S-H)/hydrocalumite/calcite was mainly responsible for the strength development in the ISSA/lime-treated sediments.展开更多
By means of ^（29）Si and ^（27）Al magic angle spinning nuclear magnetic resonance（MAS NMR） combined with deconvolution technique, X-ray diffraction（XRD）, scanning electron microscopy（SEM） as well as energy dis...By means of ^（29）Si and ^（27）Al magic angle spinning nuclear magnetic resonance（MAS NMR） combined with deconvolution technique, X-ray diffraction（XRD）, scanning electron microscopy（SEM） as well as energy dispersive X-ray system（EDX）, the effect of 5 wt% corrosive solutions（ viz. 5 wt% Na_2SO_4, MgSO_4, Na_2SO_^（4＋）Na Cl and Na_2SO_^（4＋）Na Cl＋Na_2CO_3） on C-S-H microstructure in portland cement containing 30 wt% fly ash was investigated.The results show that, in MgSO_4 solution, Mg2＋ promotes the decalcification of C-S-H by SO_4^（2-）,increasing silicate tetrahedra polymerization and mean chain length（MCL） of C-S-H. However, the substituting degree of Al^（3＋） for Si^（4＋）（Al[4]/Si） in the paste does not change evidently. Effect of Na_2SO_4 solution on C-S-H is not significantly influenced by Na Cl solution, while the MCL and Al[4]/Si of C-S-H in fly ashcement paste slightly change. However, the decalcification of C-S-H by SO_4^（2-） and CO_3^（2-） attack, as well as the activation of fly ash by SO_4^（2-） attack will increase the MCL and Al[4]/Si, which are both higher than that under Na_2SO_4 corrosion, MgSO_4 or Na_2SO_4 ＋Na Cl coordination corrosion.展开更多
Oldoinyo Lengai mountain located in Northern Tanzania is the only active natrocarbonatite volcano with unusually alkali-rich natrocarbonatites which are not found elsewhere in the world. Volcanic ash formed earlier du...Oldoinyo Lengai mountain located in Northern Tanzania is the only active natrocarbonatite volcano with unusually alkali-rich natrocarbonatites which are not found elsewhere in the world. Volcanic ash formed earlier during eruptions was collected from different sites along the mountain, and its potency to adsorb hydrogen sulfide (H2S) and ammonia (NH3) from biogas was investigated. The samples were calcinated at different temperatures (550℃ - 850℃) and were characterized by X-ray florescent, scanning electron microscopy and X-ray diffraction techniques. The on-site adsorption experiments were conducted at the biogas digester at ambient conditions. The calcinated ash was packed into the reactor bed, biogas allowed to pass through the adsorbent, and the inlet and outlet concentrations of H2S and NH3 were measured. The height of the site where the adsorbent was taken from, calcination temperature, biogas flowrate and mass of the adsorbent were variable parameters and found to influence greatly on the efficiency of H2S and NH3 removal. The efficiency is increased with calcination temperature raise and mass of adsorbent and decreased with flowrate increase. The samples collected from the top site of the mountain and calcinated at 850℃ exhibited the best sorption performance.展开更多
The nanostructure of cementitious materials has important effects on concrete properties. The effects of rice husk ash（RHA） on cement hydration product phases and interfacial transition zone（ITZ） in mortar were in...The nanostructure of cementitious materials has important effects on concrete properties. The effects of rice husk ash（RHA） on cement hydration product phases and interfacial transition zone（ITZ） in mortar were investigated from the nano-scale structure perspective. The experimental results indicate that, with the increase of RHA dosages of samples, the volume fraction of high-density calcium-silicate-hydrate（HD C-S-H） in porosity and hydration product phases increases. The volume fractions of HD C-S-H in C-S-H of samples show an increasing trend with the increase of RHA dosages. RHA decreases the thickness of ITZ and increases the matrix elastic moduli of samples, however, the RHA dosoges hardly affect the thickness and elastic moduli.展开更多
This experimental investigation aims at evaluating the thermal properties of rice husk ash (RHA)—filled gypsum plaster composite for potential applications, as insulating materials. The thermal conductivities of comp...This experimental investigation aims at evaluating the thermal properties of rice husk ash (RHA)—filled gypsum plaster composite for potential applications, as insulating materials. The thermal conductivities of composites of gypsum plaster reinforced with RHA at 0%, 10%, 20%, 30%, and 40% volume fractions were determined experimentally using Lee’s disc method. The experimental results show that integrating RHA reduces the thermal conductivity of gypsum plaster and improves its insulation capacity. The results obtained from the experiments were compared with the Rule of Mixture Model, Maxwell Model, and Russell Model. It was observed that the thermal conductivities obtained from experiments and the theoretical models decreased with an increase in the volume fraction of RHA. The errors associated with the models with respect to experimental results are on the average of 28.7% for Mixture Rule, 31.6% for Russel Model, and 18.8% for the Maxwell Model. An agricultural waste like RHA can be beneficially used for the preparation of composites and, due to improved insulation capability, these composites can be used for applications such as insulation boards and sheathing, hardboard, ceilings of roofs, decorations, etc.展开更多
为实现火电机组按需吹灰,采用Visual Studio 2015开发工具及MySQL数据库管理系统,基于B/S架构设计并搭建了火电机组受热面在线积灰监测及吹灰优化系统平台并且成功在某600MW机组实现。该系统实现了实时在线监测锅炉各级受热面的积灰状态...为实现火电机组按需吹灰,采用Visual Studio 2015开发工具及MySQL数据库管理系统,基于B/S架构设计并搭建了火电机组受热面在线积灰监测及吹灰优化系统平台并且成功在某600MW机组实现。该系统实现了实时在线监测锅炉各级受热面的积灰状态,进而通过吹灰优化模型给出吹灰建议,为电厂运行人员提供运行指导与参考。展开更多
基金The authors would like to thank the financial support of National Natural Science Foundation of China(Grant Nos.51861165104 and 51625903)National Key Research and Development Project(Grant No.2019YFC1804002).
文摘Management of incinerated sewage sludge ash(ISSA)and dredged contaminated marine sediments(CMSs)is a great challenge for Hong Kong and other coastal cities due to limited landfilling capacity.The present study investigates the use of high content(20%of sediment by mass)of ISSA in combination with cement/lime for solidification/stabilization(S/S)treatment of CMSs to provide a way to reuse the wastes as construction materials.The results showed that ISSA being a porous material was able to absorb a large amount of water rendering a more efficient solidification process of the marine sediment which normally had a very high water content(w80%).The S/S treatment improved the engineering properties of the sediment,but reduced the workability,especially for the lime-treated samples.Lime can be used to replace ordinary Portland cement(OPC)for better heavy metal immobilization and carbon emission reduction.The hardened sediment samples prepared with 10%of lime and 20%of ISSA could attain a strength of 1.6 MPa after 28 d of curing.In addition,leaching tests confirmed that there was no environmental risk induced by these stabilized materials.The formation of hydrated cementitious compounds including calcium silicate hydrate(CeSeH)/calcium aluminate silicate hydrate(C-A-S-H)/hydrocalumite/calcite was mainly responsible for the strength development in the ISSA/lime-treated sediments.
基金Funded by the Major State Basic Research Development Program of China(“973” Program)(No.2015CB655101)Natural Science Foundation of Hebei(No.E2016209283)+1 种基金National Natural Science Foundation of China(No.51402003)Open Foundation of Road Bridge and Structural Engineering Key Laboratory WHUT,China(No.DQZDJJ201504)
文摘By means of ^（29）Si and ^（27）Al magic angle spinning nuclear magnetic resonance（MAS NMR） combined with deconvolution technique, X-ray diffraction（XRD）, scanning electron microscopy（SEM） as well as energy dispersive X-ray system（EDX）, the effect of 5 wt% corrosive solutions（ viz. 5 wt% Na_2SO_4, MgSO_4, Na_2SO_^（4＋）Na Cl and Na_2SO_^（4＋）Na Cl＋Na_2CO_3） on C-S-H microstructure in portland cement containing 30 wt% fly ash was investigated.The results show that, in MgSO_4 solution, Mg2＋ promotes the decalcification of C-S-H by SO_4^（2-）,increasing silicate tetrahedra polymerization and mean chain length（MCL） of C-S-H. However, the substituting degree of Al^（3＋） for Si^（4＋）（Al[4]/Si） in the paste does not change evidently. Effect of Na_2SO_4 solution on C-S-H is not significantly influenced by Na Cl solution, while the MCL and Al[4]/Si of C-S-H in fly ashcement paste slightly change. However, the decalcification of C-S-H by SO_4^（2-） and CO_3^（2-） attack, as well as the activation of fly ash by SO_4^（2-） attack will increase the MCL and Al[4]/Si, which are both higher than that under Na_2SO_4 corrosion, MgSO_4 or Na_2SO_4 ＋Na Cl coordination corrosion.
文摘Oldoinyo Lengai mountain located in Northern Tanzania is the only active natrocarbonatite volcano with unusually alkali-rich natrocarbonatites which are not found elsewhere in the world. Volcanic ash formed earlier during eruptions was collected from different sites along the mountain, and its potency to adsorb hydrogen sulfide (H2S) and ammonia (NH3) from biogas was investigated. The samples were calcinated at different temperatures (550℃ - 850℃) and were characterized by X-ray florescent, scanning electron microscopy and X-ray diffraction techniques. The on-site adsorption experiments were conducted at the biogas digester at ambient conditions. The calcinated ash was packed into the reactor bed, biogas allowed to pass through the adsorbent, and the inlet and outlet concentrations of H2S and NH3 were measured. The height of the site where the adsorbent was taken from, calcination temperature, biogas flowrate and mass of the adsorbent were variable parameters and found to influence greatly on the efficiency of H2S and NH3 removal. The efficiency is increased with calcination temperature raise and mass of adsorbent and decreased with flowrate increase. The samples collected from the top site of the mountain and calcinated at 850℃ exhibited the best sorption performance.
基金Funded by the National Natural Science Foundation of China(Nos.51602198,41427802 and 41302257)the Zhejiang Provincial Natural Science Foundation of China(No.LQ13D020001)the Shaoxing University Scientific Research Project(No.20145030)
文摘The nanostructure of cementitious materials has important effects on concrete properties. The effects of rice husk ash（RHA） on cement hydration product phases and interfacial transition zone（ITZ） in mortar were investigated from the nano-scale structure perspective. The experimental results indicate that, with the increase of RHA dosages of samples, the volume fraction of high-density calcium-silicate-hydrate（HD C-S-H） in porosity and hydration product phases increases. The volume fractions of HD C-S-H in C-S-H of samples show an increasing trend with the increase of RHA dosages. RHA decreases the thickness of ITZ and increases the matrix elastic moduli of samples, however, the RHA dosoges hardly affect the thickness and elastic moduli.
文摘This experimental investigation aims at evaluating the thermal properties of rice husk ash (RHA)—filled gypsum plaster composite for potential applications, as insulating materials. The thermal conductivities of composites of gypsum plaster reinforced with RHA at 0%, 10%, 20%, 30%, and 40% volume fractions were determined experimentally using Lee’s disc method. The experimental results show that integrating RHA reduces the thermal conductivity of gypsum plaster and improves its insulation capacity. The results obtained from the experiments were compared with the Rule of Mixture Model, Maxwell Model, and Russell Model. It was observed that the thermal conductivities obtained from experiments and the theoretical models decreased with an increase in the volume fraction of RHA. The errors associated with the models with respect to experimental results are on the average of 28.7% for Mixture Rule, 31.6% for Russel Model, and 18.8% for the Maxwell Model. An agricultural waste like RHA can be beneficially used for the preparation of composites and, due to improved insulation capability, these composites can be used for applications such as insulation boards and sheathing, hardboard, ceilings of roofs, decorations, etc.
文摘为实现火电机组按需吹灰,采用Visual Studio 2015开发工具及MySQL数据库管理系统,基于B/S架构设计并搭建了火电机组受热面在线积灰监测及吹灰优化系统平台并且成功在某600MW机组实现。该系统实现了实时在线监测锅炉各级受热面的积灰状态,进而通过吹灰优化模型给出吹灰建议,为电厂运行人员提供运行指导与参考。
