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Study on soil solidification based on microbiological precipitation of CaCO_3

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Science china(Technological Sciences) 2010年第9期53卷 2372-2377页

作者： LU WangJie,QIAN ChunXiang & WANG RuiXing School of materials Science & Engineering,jiangsu key laboratory for construction materials,Southeast University,nanjing 210089,china School of materials Science & Engineering Jiangsu Key Laboratory for Construction Materials Southeast University Nanjing China

The soil solidifying technology started booming from the 1940s and formed an integrated *** paper aimed to study the effect and mechanism of soil solidification by *** specimens treated by different methods were *** the compressive strengths of these specimens on day 7 were tested and the situ bacteria culturing technique in soil was *** the mechanism of soil solidification by microorganisms was explored according to the decomposition rate of substrate,pH value and the SEM and XRD *** results showed that the soil could be solidified by filling enhancement and precipitation of *** compressive strength increased with bacteria A but decreased with substrate B,and soil specimen got a higher strength with bacteria situ *** suitable pH value for bacteria A was 8–9,and the delay of lime addition could make substrate decomposition more completely,lower the influence by the existence of substrate,and improve the *** XRD and SEM images,precipitation of CaCO3 could be speculated.

关键词： soil solidification bacteria compressive strength situ cultured decomposition rate precipitation

Comparison of the fracture process of the rubberized concrete and plain concrete under bending load

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Science china(Technological Sciences) 2010年第6期53卷 1526-1533页

作者： ZHANG YaMei1,WANG Chao2,LU Yi1 & MA AiBin2 1 jiangsu key laboratory of construction materials,Southeast University,nanjing 2.1189,china 2 College of materials Science and Engineering,Hohai University,nanjing 210098,china jiangsu key laboratory of construction materials Southeast University Nanjing China College of materials Science and Engineering Hohai University Nanjing China

Acoustic emission (AE) technique is employed to investigate the damage process of the notched plain concrete and rubberized concrete specimens under 3-point bending *** signals in the fracture process of notched specimens are illustrated by analyzing the distribution of amplitude and hit rate of AE *** signals in the rubberized concrete have lower activity and amplitude than in the plain *** AE location analysis,it is found that the high energy events mainly are distributed near the notch *** to AE energy,the fracture process zone (FPZ) is *** comparing the FPZ of both concretes,it is found that the incorporation of rubber particles in concrete can greatly alleviate the damage process of concrete specimens and the damage zone in the rubberized concrete is much smaller than in the plain *** moment tensor is also used to analyze the type of cracks and it is found that tensile cracks dominate the early period of loading,while shear cracks become dominant with propagation of cracks in late load period.

关键词： concrete rubberized concrete acoustic emission damage moment tensor

Influence of Absolute Basicity and Capillary Porosity on Carbonation of Concrete

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Journal of Wuhan University of Technology(materials Science) 2010年第5期25卷 889-892页

作者：巴明芳 School of materials Science and Engineering Southeast University jiangsu key lab of construction materials

The single influence of capillary porosity and coupling effects of absolute basicity and capillary porosity on concrete carbonation were investigated. The experimental results showed that carbonation rate of concrete at a given absolute basicity （AB） increased moderately with the increase of the porosity ranging from 6.2% to 9.25%, and increased rapidly with porosity from 9.25% to 12.8%.The coupling effect mainly embodied in disappeared mutation point of capillary porosity, and the distributing regions of carbonation depth were clearly partitioned in the coupling influence of absolute basicity and capillary porosity. A design method on carbonation related durability of concrete based on the coupling effects was proposed.

关键词： absolute basicity capillary porosity coupling effects carbonation rate

Cementation of sand grains based on carbonate precipitation induced by microorganism

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Science china(Technological Sciences) 2010年第8期53卷 2198-2206页

作者： QIAN ChunXiang,PAN QingFeng &WANG RuiXing jiangsu key laboratory of construction materials,School of materials Science&Engineering,Southeast University,nanjing 2.1189,china jiangsu key laboratory of construction materials School of Materials Science & Engineering Southeast University Nanjing China

Microbes can produce 2 3 CO32-in an environment conductive to precipitation,so the incompact sands will be *** technology is environmentally friendly not only because it gives strength to the sand body,but also it allows water to penetrate into the sand body,which is unlike silicate cement that will destroy the ecosystem of the *** comparing the activity of three kinds of bacteria,the most suitable one was chosen for the ***,the activity of this bacterium was still not high enough for the purpose,so it was purified.A suitable program for the consolidation and cementation of sands was also found in the *** compressive strength and the porosity of the cemented sand body were tested to characterize the cementation *** analysis showed that a new phase of calcite was produced between sand *** content of calcite was detected by *** study showed that the precipitation program was quite important to obtain a sound cemented sand body in addition to the activity of the bacteria.

关键词： carbonate precipitation microbe calcite sand consolidation porosity compressive strength

Two-and Three-Dimensional Chloride Ingress into Fly Ash Concrete

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Journal of Wuhan University of Technology(materials Science) 2011年第5期26卷 978-982页

作者：张云升 jiangsu key laboratory for construction materials Southeast University College of materials Science and Engineering Southeast University

2D,3D chloride ion concentration at the edge and corner zones were systematically investigated for fly ash concretes made with different cement replacement percentage by fly ash （0%,10%,20%,40%,60%）,water to binder ratios （0.3,0.35,0.4）,and curing ages （28 d,90 d）.An interaction effect caused by 2D and 3D diffusion could obviously be observed through the comparison with 1D testing *** order to quantify the interaction effect,2D and 3D diffusion interaction coefficients was proposed in this ***,the changes of 2D and 3D interaction coefficients with the change in the free chloride ion concentration were *** above research provide an insight into chloride ion attack on the edge and corner reinforcing bars of concrete structures in the field of civil engineering.

关键词： fly ash concrete chlorides two and three dimension ingress

The inversion of the real kinematic properties of coronal mass ejections by forward modeling

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Research in Astronomy and Astrophysics 2011年第2期11卷 237-244页

作者： You Wu 1 and Peng-Fei Chen 1,2 1 Department of Astronomy,nanjing University,nanjing 210093,china 2 key lab of Modern Astron.and Astrophys.,Ministry of Education,nanjing 210093,china Department of Astronomy Nanjing University Nanjing 210093 China key lab of Modern Astron. and Astrophys. Ministry of Education Nanjing 210093 China

Kinematic properties of coronal mass ejections （CMEs） suffer from projection effects,and it is expected that the real velocity should be larger and the real angular width should be smaller than the apparent *** attempts have been taken to correct the projection effects,which however led to an inflated average velocity probably due to the biased choice of CME *** order to estimate the overall influence of the projection effects on the kinematic properties of the CMEs,we perform a forward modeling of real distributions of CME properties,such as the velocity,the angular width,and the latitude,by requiring their projected distributions to best match *** a matching is conducted by Monte Carlo *** to the derived real distributions,we found that （1） the average real velocity of all non-full-halo CMEs is about 514 km s-1,and the average real angular width is about 33°,in contrast to the corresponding apparent values of 418 km s-1 and 42.7° in observations;（2） For the CMEs with the angular width in the range of 20°-120°,the average real velocity is 510 km s-1 and the average real angular width is 43.4°,in contrast to the corresponding apparent values of 392 km s-1 and 52° in observations.

关键词： Sun: coronal mass ejections (CMEs) -- methods: statistical -- methods:numerical

Miocene Bahean stratigraphy in the Longzhong Basin, northern central china and its implications in environmental change

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Science china Earth Sciences 2006年第12期49卷 1270-1279页

作者： LI Jijun1,2, ZHANG Jun1, SONG Chunhui1, ZHAO Zhijun2, ZHANG Yong1, WANG Xiuxi 1, ZHANG Jianming1 & CUI Qiaoyu1 1. key laboratory of Western china’s Environmental Systems (Ministry of Education) & College of Earth and Environment Sciences, Lanzhou University, Lanzhou 730000, china 2. jiangsu key laboratory of Environmental Change and Ecological construction & College of Geography, nanjing Normal University, nanjing 210097, china key laboratory of Western china’s Environmental Systems (Ministry of Education) & College of Earth and Environment Sciences Lanzhou University Lanzhou China jiangsu key laboratory of Environmental Change and Ecological construction & College of Geography Nanjing Normal University Nanjing China

Fossil mammal-riched Neogene strata are widely distributed in the southeast corner of the huge Longzhong Basin at Tianshui, Gansu Province, northern central china. Hipparion weihoense, a typical member of late Middle Miocene Bahean stage, was recently excavated at Yaodian along a well-exposed outcrop. Owing to the importance of the Bahean stage in the mammalian evolution and its potential for environmental change, we suggested a name of Yaodian Formation for the stratigra- phy, which is correlated to the Bahe Formation at Lantian, Shaanxi. High resolution paleomagnetic dating of the section shows that the Yaodian Formation covers the period between 11.67 Ma and 7.43 Ma, with the site bearing Hipparion weihoense being estimated at about 10.54―10.30 Ma, providing first magnetostratigraphic chronology for the Bahean Stage. The Yaodian Formation consists of fluvial channel deposits (11.67―10.40 Ma) at the bottom, floodplain deposits in the middle (10.40―9.23 Ma) and shallow lake sediments at the top (9.23―7.43 Ma). This upward fining sequence suggests that the relief in nearby mountain ranges such as West Qinling to the south and Huajia Ling to the north was greatly reduced after long-term denudation, fluvial transport capacity was low, and finally the drainage system was disintegrated, replaced with broad-shallow lakes in which only fine sediments like mud and marlite were deposited, indicating an old stage of development of a planation surface. A remarkable shift in ecology and climatic environment was found at 7.4―7.7 Ma when paleoclimate changed from early warm humid to late dry as indicated by sedimentary facies changed from early shallow lake sequence to late eolian red clays and a former coniferous-deciduous mixed forest was replaced by grassland, leading to great growth of Hipparion Fauna of Baodean stage in the region. Therefore, it is estimated that the present high relief of Qinling and drainage pattern did not come into being until Late Pliocene in response

关键词： Bahean stage,magnetostratigraphy,Yaodian Formation,Neogene,Longzhong Basin.

Degradation of Pore Structure and Microstructures in Hardened Cement Paste Subjected to Flexural Loading and Wet-dry Cycles in Sea Water

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Journal of Wuhan University of Technology(materials Science) 2009年第6期24卷 940-944页

作者：张武满 School of Transportation Science and Engineering Beihang University jiangsu key laboratory of construction materials Southeast University

Hardened cement paste was subjected to the flexural loading and wet-dry cycles in sea water. The degradation of microstructures was obtained using scanning electron microscope （SEM）, and the energy dispersive spectrum （EDS） analysis was carried to analyze the local composition. Mercury intrusion porosimetry （Poremaster GT-60） was used to analyze the degradation of pore structures. The experimental results show that the synergistic action of the flexural loading, wet-dry cycles and sea water leads to significant deterioration of hardened cement paste. The degradation of microstructures in the tensile region is more serious than that in the compressive region. The flexural loading and wet-dry cycles accelerate the chemical attack of sea water.

关键词： hardened cement paste pore structure microstructures flexural loading wet-dry cycles sea water

Single and Multiple Dynamic Impacts Behaviour of Ultra-high Performance Cementitious Composite

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Journal of Wuhan University of Technology(materials Science) 2011年第6期26卷 1227-1234页

作者：张文华张云升 Department of materials Science and Engineering Jiangsu Key Laboratory of Construction MaterialsSoutheast University

Single and multiple dynamic impacts tests were conducted on ultra-high performance cementitious composite （UHPCC） with various volume fractions of steel fibers （0, 1%, 2%, 3%, 4%） by using the split hopkinson pressure bar （SHPB）. Besides, the ultrasonic velocity method was used to test the damage on specimens caused by dynamic impacts. For single dynamic impact, the data suggest that UHPCC obviously presents dynamic strength enhancement. With increasing of strain rate, the peak stress and peak strain increase rapidly. For multiple dynamic impacts, the results show that addition of steel fibers can obviously enhance the properties of UHPCC to resist the repeated dynamic impacts. Firstly, the number of impacts sharply increases with the increasing of volume fraction of steel fibers. Secondly, the energy absorption ability linearly increases with addition of steel fibers. Thirdly, the steel fibers can prevent the disruption phenomenon and maintain the integrity of specimen.

关键词： UHPCC SHPB dynamic behavior multiple impacts