检索结果-南通市图书馆

Agglomeration Characteristics of river sand and Wheat Stalk Ash Mixture at High Temperatures

Journal of Thermal Science 2013年第1期22卷 64-70页

作者： Shang Linlin Li Shiyuan Lu Qinggang College of Mechanical and Transportation Engineering China University of Petroleum(Beijing Campus) Institute of Engineering Thermophysics Chinese Academy of Sciences

The agglomeration characteristics of river sand and wheat stalk ash mixture at various temperatures are investi- gated using a muffle furnace. The surface structural changes, as well as the elemental makeup of the surface and cross-section of the agglomerates, are analyzed by polarized light microscopy, scanning electron microscopy （SEM）, and energy dispersive X-ray （EDX）. Multi-phase equilibrium calculation is performed with FactSage in identifying the melting behavior of the river sand-wheat stalk ash mixture at high temperatures. No indication of agglomeration is detected below 850~C. At a temperature of 900-1000~C, however, obvious agglomeration is observed and the agglomerates solidify further as temperature increases. The presence of potassium and calcium enrichment causes the formation of a sticky sand surface that induces agglomeration. The main component of the agglomerate surface is KEO-42aO-SiO2, which melts at low temperatures. The formation of molten silicates causes particle cohesion. The main ingredient of the binding phase in the cross-section is K20-SiO2-Na20- Al2Oa--CaO; the agglomeration is not the result of the melting behavior of wheat stalk ash itself but the compre- hensive results of chemical reaction and the melting behavior at high temperatures. The multi-phase equilibrium calculations agree well with the experimental results.

关键词： Wheat stalk ash river sand Agglomeration Phase equilibria Microstructure

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

river sand Characterization for Its Use in Concrete: A Revue

引用

Open Journal of Civil Engineering 2023年第2期13卷 353-366页

作者： Muhindo Wa Muhindo Abdias Manjia Marcelline Blanche Ursula Joyce Pettang Nana Henry Fonbeyin Abanda Ngapgue François Pettang Chrispin Laboratory Engineering Civil and Mechanics Doctoral Research Unit for Engineering and Applications University of Yaoundé I Yaoundé Cameroon Buildings and Publics Works Section Institute of Building and Public Works Butembo Democratic Republic of Congo Department of Civil Engineering National Advanced School of Engineering University of Yaoundé 1 Yaoundé Cameroon Faculty of Technology Design and Environment Oxford Brookes University Oxford UK Department of Civil Engineering Fotso Victor University Institute of Technology University of Dschang Bandjoun Cameroon

Despite the gradual professionalization of the construction sector as well as the abundance of sand mining sites offered by the North Kivu, Democratic Republic of Congo Region, ignorance of materials by local builders persists. This is the case of quarries extracting river sand used to make concrete and mortar. However, the dosages of the various constituents are most often chosen on the basis of experience without any prior characterization of this material. This paper presents a comprehensive review of the characterization of river sand for its use in concrete in DRC. The origin and global use of river sand in construction are presented in percentage terms to highlight the importance of river sand as a construction material. The physical properties of river sand, including particle size distribution, bulk density, absolute density, and cleanliness are discussed in detail. The paper examines the effect of variations in river sand properties on concrete behavior, including density and compressive strength. Overall, this paper emphasizes the need to properly characterize river sand before using it in construction to ensure durable, high-quality structures. This will avoid the problems that are observed in particular a bad behavior of the coating on the walls;cracks and crumbling of the beams, lintels, posts and even the ruin of the structures.

关键词： Characterization river sand Concrete Construction Material Structure

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Assessment of Bholari river sand for Its Geotechnical Characterization as Fine Aggregate

引用

Hydro Science & Marine Engineering 2022年第1期4卷 27-35页

作者： Salman Arif Adnan Khan Sumaira Asif Khan Department of Geology University of KarachiKarachiSindhPakistan

Present study is aimed at assessment of Bholari river sand for its geotechnical characterization and suitability as fine aggregate which is being quarried in Jamshoro district,Sindh,*** this purpose,sand samples(n=11)were collected from quarry sites and main river *** properties reveal that Bholari sand is mainly coarse to fine in size(0.2 mm-5 mm).Average values of fineness modulus,specific gravity,bulk density and void content of collected samples are 2.58,2.56,1659.90 kg/m^(3) and 35.12%respectively which varied within the corresponding permissible ranges of ACI(American Concrete Institute).Carbonate content of about 57.59%is also in agreement with corresponding range for fine *** examination revealed that Bholari river sand mainly comprises of quartz and rock fragments with subordinate limestone *** per classification of Dott(1964),Bholari sand is lithic arenite where quartz(50%)occurs as main mineral followed by rock fragments(30%),feldspars(15%)and other opaque minerals(5%).Texturally,the sediments are angular(77%)to sub-round(33%).All these physical properties lie within the range set by National Highway Authority(NHA)and American Standard of Testing Material(ASTM).It is concluded that Bholari river sand is suitable for use in concrete mixed with cement and asphalt.

关键词： river sand Bholari Geotechnical characterization Fine aggregate

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Impact assessment of river sand resource shortage under different policy scenarios in China

引用

Low-carbon Materials and Green Construction 2023年第1期1卷 205-217页

作者： Jianzhuang Xiao Hanghua Zhang Xiaolong Hu Tao Ding Xuwen Xiao Department of Structural Engineering College of Civil EngineeringTongji UniversityShanghai 200092China Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina

More than half of the annual global concrete materials were produced in China due to the rapid developing construction industry,which partly led to the shortage of river ***,mining rate exceeds the natural replenishment rate of river sand recently,resulting in depletion of natural river sand *** increasing demand of river sand influences lots of aspects including altered landforms,increasing carbon emissions,ecological deterioration,international trades and *** face the river sand resource shortage in China and to propose possible coping strategies,the data of river sand for construction in China and other related data were collected,and it is suggested that effective policy measures should be taken right now to protect river sand and strictly manage sand *** solutions for river sand shortage can be summarized as“5Rs”principle,which includes reduce,***,replace and *** dynamic model is established to predict the trend of river sand shortage and it was predicted that the gap between river sand supply and demand will come up to 63%.The impact of three policy scenarios is tested in the model,and the gap can be reduced to 35%by single policy scenario,while the scenario with all policy measures is able to reduce the contradiction between supply and demand to 4%.Suggestions are proposed from the aspects of structural and material technology,policy measures and international *** should be paid to the shortage of river resources,to realize the sustainable development of the construction industry and other related industries,and to promote the harmonious coexistence of human and nature.

关键词： river sand Sustainable concrete 5Rs principle Construction industry Policy scenario

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Grinding Properties of Abandoned Concrete

引用

Journal of China University of Mining and Technology 2007年第2期17卷 281-285页

作者： ZHENG Fang-yu WANG Li-jiu LI Qiang School of Civil and Hydraulic Engineering Dalian University of Technology Dalian Liaoning 116024 China

The grinding properties of abandoned concrete, which consists primarily of hardened cement, limestone aggregate and river sand, are studied. Theoretical models of grinding are used to explain the experimental observation. The results show that 1) The principle disintegration mechanism of hardened cement and river sand is volumetric grinding, although at later stages grinding of cement becomes difficult because of its flaked structure; 2) The lime- stone grinding process can be divided into two steps. First, volumetric grinding, with an obvious component of surface grinding, followed by primarily surface grinding as the micro-particle content increases; 3) Initially, the principle mechanism of grinding limestone and river sand is volumetric grinding, albeit less efficient grinding than if these components were ground separately, and; 4) After 10 to 20 min of grinding the grinding bottleneck phenomenon ap- pears and after 20 min of grinding the content of micro-particles is large and surface grinding is the main mechanism while the particle size of the mixture is smaller than that of separately ground river sand and cement but bigger than that of separately ground limestone.

关键词： abandoned concrete cement stone limestone river sand grinding

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Electroplating wastewater treatment technology by river sands

引用

Acta Geochimica 2006年第S1期 93-93页

作者： Xubo GAO School of Environmental Studies, China University of Geosciences, Wuhan 430074, China

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：