The bio-sandstone, which was cemented by microbe cement, was firstly prepared, and then the microstructure evolution process was studied by X-ray computed tomography （X-CT） technique. The experimental results indica...The bio-sandstone, which was cemented by microbe cement, was firstly prepared, and then the microstructure evolution process was studied by X-ray computed tomography （X-CT） technique. The experimental results indicate that the microstructure of bio-sandstone becomes dense with the development of age. The evolution of inner structure at different positions is different due to the different contents of microbial induced precipitation calcite. Besides, the increase rate of microbial induced precipitation calcite gradually decreases because of the reduction of microbe absorption content with the decreasing pore size in bio-sandstone.展开更多
Microbe cementitious material as a binder has been developed due to the ever increasing awareness of environmental protection.The new cementitious material relies on microbiologically induced precipitation of calcium ...Microbe cementitious material as a binder has been developed due to the ever increasing awareness of environmental protection.The new cementitious material relies on microbiologically induced precipitation of calcium carbonate to bind loose particles or repair surface defects and cracks of cement-based material.This paper elaborates the research on loose sand particles cemented by microbe cement from three aspects:compressive strength,pore structure and microstructure.In addition,the research on restoration surface defects and cracks of cement-based material by microbe cement is introduced from two parameters:surface water absorption and compressive strength recover coefficient.The results show that microbe cementitious material can bind loose particles and repair surface defects or cracks of cement-based material.展开更多
Microbe cement,a new type of gelling material,has attracted wide attention due to the increasing awareness of environmental protection.In this paper,the microbe cement in solidifying municipal solid waste incineration...Microbe cement,a new type of gelling material,has attracted wide attention due to the increasing awareness of environmental protection.In this paper,the microbe cement in solidifying municipal solid waste incineration(MSWI)fly ash is investigated and the effect of the microbial induction method in solidifying MSWI fly ash is compared with the traditional chemical reaction strategy by characterizing the resulted calcite and the solidification productions with electronic universal testing machine,X-ray diffractometer(XRD),Fourier transform infrared spectrometer(FTIR),scanning electron microscope(SEM)and atomic absorption spectrometer.The results show that the MSWI fly ash solidified by microbe cement has the highest compressive strength while that of the chemical CaCO3 products is the lowest.The XRD results show that a new hydration gelling substance(Ca2SiO4·0.30H2O)is generated in the MSWI fly ash products.The FTIR results show that the frequency of Si-O bonds and C-O bonds in the products solidified by microbe cement has shifted,while there is no change occurred in the chemical CaCO3 products.The SEM results show that the microstructure of the products solidified by microbe cement is denser than that of chemical CaCO3 products.The test results of heavy metals show that the microbe cement could reduce the leaching concentration of heavy metals in MSWI fly ash.Ultimately,the leaching concentration of Pb meets the standard requirements,while that of Cd is still slightly higher than the standard requirement.展开更多
A new generation of cement,microbe cement,has been developed in response to the ever increasing awareness of environmental protection.Microbe cement is a new strengthening material based on microbiologically induced p...A new generation of cement,microbe cement,has been developed in response to the ever increasing awareness of environmental protection.Microbe cement is a new strengthening material based on microbiologically induced precipitation of calcium carbonate.This paper confirms the feasibility of binding loose sand particles using microbe cement and details the cementation mechanism of microbe cement.We have also prepared microbe cementitious materials(biosandstones).The compressive strength of the bio-sandstone,which depends on the content of calcium carbonate produced by microbially induced precipitation and the bio-mediated calcite crystal size,could be up to 12 MPa at an age of 20 days.By increasing the precipitated calcite content,the compressive strength and microstructure of bio-sandstone could be improved.展开更多
Microbe cement as a new bonding material is presented. Sandstone （0.05 m diameter, 0.5 m height） and sandpile （0.125 m^3） are joined by microbe cement to make a whole body. Evolutions in the related properties of ...Microbe cement as a new bonding material is presented. Sandstone （0.05 m diameter, 0.5 m height） and sandpile （0.125 m^3） are joined by microbe cement to make a whole body. Evolutions in the related properties of treated sand samples are examined through compressive strength and calcite content. Results indicate that the structure of the cemented body is nonuniform, that the calcite content decreases with distance from the injection port, and that the compressive strength also decreases with dis- tance from the injection port. In addition, evolutions in the measured calcite content and compressive strength are summarized by a numerical model that considers microbe concentration distribution. The numerical results of the calcite content at different positions for 0.5 m height sandstone are similar to the test results, and the experimental results for calcite content and compres- sive strength of 0.125 m^3 cubic sandpile are similar to the numerical results. Prediction results indicate that the simulations should become a significant supplementary tool when microbe cement is applied in actual engineering projects.展开更多
基金Funded by the National Natural Science Foundation of China(No.51072035),the Ph D Program’s Foundation of Ministry of Education of China(No.20090092110029)the Research Innovation Program for College Graduates of Jiangsu Province(No.CXZZ_0145)the Scientific Research Foundation of Graduate School of Southeast University(Nos.YBJJ1127 and YBPY1208)
文摘The bio-sandstone, which was cemented by microbe cement, was firstly prepared, and then the microstructure evolution process was studied by X-ray computed tomography （X-CT） technique. The experimental results indicate that the microstructure of bio-sandstone becomes dense with the development of age. The evolution of inner structure at different positions is different due to the different contents of microbial induced precipitation calcite. Besides, the increase rate of microbial induced precipitation calcite gradually decreases because of the reduction of microbe absorption content with the decreasing pore size in bio-sandstone.
基金the National Natural Science Foundation of China(No.51072035)the Ph.D.Program's Foundation of Ministry of Education of China (No.20090092110029)+1 种基金the Research Innovation Program for College Graduates of Jiangsu Province (No.CXZZ 0145)the Scientific Research Foundation of Graduate School of Southeast University (No.YBJJ1127)
文摘Microbe cementitious material as a binder has been developed due to the ever increasing awareness of environmental protection.The new cementitious material relies on microbiologically induced precipitation of calcium carbonate to bind loose particles or repair surface defects and cracks of cement-based material.This paper elaborates the research on loose sand particles cemented by microbe cement from three aspects:compressive strength,pore structure and microstructure.In addition,the research on restoration surface defects and cracks of cement-based material by microbe cement is introduced from two parameters:surface water absorption and compressive strength recover coefficient.The results show that microbe cementitious material can bind loose particles and repair surface defects or cracks of cement-based material.
基金the National Nature Science Foundation of China(Nos.51978439 and 51708390)the Tianjin Transport Technology Development Project(No.2018-38)+1 种基金the Project Funded by China Postdoctoral Science Foundation(No.2019M651000)the Tianjin Rail Transit Major Special Project(No.18ZXGDGX00050)。
文摘Microbe cement,a new type of gelling material,has attracted wide attention due to the increasing awareness of environmental protection.In this paper,the microbe cement in solidifying municipal solid waste incineration(MSWI)fly ash is investigated and the effect of the microbial induction method in solidifying MSWI fly ash is compared with the traditional chemical reaction strategy by characterizing the resulted calcite and the solidification productions with electronic universal testing machine,X-ray diffractometer(XRD),Fourier transform infrared spectrometer(FTIR),scanning electron microscope(SEM)and atomic absorption spectrometer.The results show that the MSWI fly ash solidified by microbe cement has the highest compressive strength while that of the chemical CaCO3 products is the lowest.The XRD results show that a new hydration gelling substance(Ca2SiO4·0.30H2O)is generated in the MSWI fly ash products.The FTIR results show that the frequency of Si-O bonds and C-O bonds in the products solidified by microbe cement has shifted,while there is no change occurred in the chemical CaCO3 products.The SEM results show that the microstructure of the products solidified by microbe cement is denser than that of chemical CaCO3 products.The test results of heavy metals show that the microbe cement could reduce the leaching concentration of heavy metals in MSWI fly ash.Ultimately,the leaching concentration of Pb meets the standard requirements,while that of Cd is still slightly higher than the standard requirement.
基金supported by the National Natural Science Foundation of China(51072035)Ph.D.Program’s Foundation of Ministry of Education of China(20090092110029)+1 种基金Research Innovation Program for College Graduates of Jiangsu Province(CXZZ_0145)Scientific Research Foundation of Graduate School of Southeast University(YBJJ1127)
文摘A new generation of cement,microbe cement,has been developed in response to the ever increasing awareness of environmental protection.Microbe cement is a new strengthening material based on microbiologically induced precipitation of calcium carbonate.This paper confirms the feasibility of binding loose sand particles using microbe cement and details the cementation mechanism of microbe cement.We have also prepared microbe cementitious materials(biosandstones).The compressive strength of the bio-sandstone,which depends on the content of calcium carbonate produced by microbially induced precipitation and the bio-mediated calcite crystal size,could be up to 12 MPa at an age of 20 days.By increasing the precipitated calcite content,the compressive strength and microstructure of bio-sandstone could be improved.
基金supported by the National Nature Science Foundation of China(Grant No.51372038)the “333” Project of Jiangsu Province
文摘Microbe cement as a new bonding material is presented. Sandstone （0.05 m diameter, 0.5 m height） and sandpile （0.125 m^3） are joined by microbe cement to make a whole body. Evolutions in the related properties of treated sand samples are examined through compressive strength and calcite content. Results indicate that the structure of the cemented body is nonuniform, that the calcite content decreases with distance from the injection port, and that the compressive strength also decreases with dis- tance from the injection port. In addition, evolutions in the measured calcite content and compressive strength are summarized by a numerical model that considers microbe concentration distribution. The numerical results of the calcite content at different positions for 0.5 m height sandstone are similar to the test results, and the experimental results for calcite content and compres- sive strength of 0.125 m^3 cubic sandpile are similar to the numerical results. Prediction results indicate that the simulations should become a significant supplementary tool when microbe cement is applied in actual engineering projects.
