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Sample records for cast in place concrete

  1. Cast-in-place concrete thin-wall pipe pile as barrier for vibration isolation

    Institute of Scientific and Technical Information of China (English)

    张富有; 陈灿寿; 魏良甲; 张霆

    2008-01-01

    Three dimensional analysis was performed by regarding vibration isolation performance cast-in-place concrete thin-wall pipe pile (PCC) and using the finite element analysis software ANSYS. The ground vertical amplitude was analyzed behind the single row cast-in-place concrete thin-wall pipe pile after the source vibration, and the influencing factors were also studied. The results indicate that in the one time of wavelength before the barrier, the oscillation amplitude is weakened; meanwhile the range which covers 4 times wavelength behind the barrier has a good vibration isolation effect, when the distance is larger than the barrier latter 4 times wavelength vibration isolation expiration.

  2. Optimum design of one way concrete slabs cast against Textile Reinforced Concrete Stay-in-Place Formwork Elements

    OpenAIRE

    Papantoniou, Ioannis; Papanicolaou, Catherine; Triantafillou, Thanasis

    2009-01-01

    This study presents a conceptual design process for one-way reinforced concrete slabs cast over Textile Reinforced Concrete (TRC) Stay-in-Place (SiP) formwork elements, aiming at the minimization of the composite slab cost satisfying Ultimate Limit State (ULS) and Serviceability Limit State (SLS) design criteria. The thin-walled TRC element is considered to participate in the structural behaviour of the composite slab. This distinct function of the TRC element (as formwork and as a part of a ...

  3. Field study of plastic tube cast-in-place concrete pile

    Institute of Scientific and Technical Information of China (English)

    陈永辉; 曹德洪; 王新泉; 杜海伟; 张霆

    2008-01-01

    The compositions, technical principles and construction equipments of a new piling method used for ground improvement plastic tube cast-in-place concrete pile were introduced. The results from static load tests on single piles with different forms of pile shoes and on their composite foundations were analyzed. The distribution patterns of axial force, shaft friction and toe resistance were studied based on the measurements taken from buried strain gauges. From the point of engineering application, the pile has merits in convenient quality control, high bearing capacity and reliable quality, showing higher reasonability, advancement and suitability than other ground improvement methods. The pile can be adopted properly to take place of ordinary ground improvement method, achieving greater economical and social benefits.

  4. Cast in place temperature 5 influence on fresh concrete made with limestone filler and blended cement

    Directory of Open Access Journals (Sweden)

    Soria, E. A.

    2003-12-01

    Full Text Available Properties of fresh concrete play a relevant role on placing and consolidation; and its design strength and durability depends on them. It is well known too that the concrete temperature during placing affects all its properties in different ways and extent. This paper presents the influence of placing temperature of concretes made with portland cement, limestone filer cement and blended cement, commercially available, on slump, slump loss, setting time and bleeding. The results show that generally when concrete temperature rises, the bleeding and slump fall down and the slump loss and setting time are accelerated. However, regardless of the strength class the type of cement affects the value of these variations

    Las propiedades de los hormigones en estado fresco desempeñan un papel fundamental durante las operaciones de colocación y compactación de los mismos y de ellas depende, en gran medida, que se alcance en el estado endurecido la resistencia y la durabilidad de diseño. Es sabido, además, que la temperatura que alcanza un hormigón durante dichas operaciones, afecta en mayor o menor grado a todas sus propiedades, de manera diferente. En el presente trabajo se analizó la influencia de la temperatura de colocación sobre el asentamiento, la pérdida del asentamiento en el tiempo, los tiempos de fraguado y la exudación, en hormigones elaborados con cemento portland normal, fillerizado y compuesto, de procedencia comercial. Los resultados han mostrado, en general, que con el aumento de la temperatura de colocación disminuyen la exudación y el asentamiento; mientras que la pérdida de asentamiento y los tiempos de fraguado se aceleran. Sin embargo, las magnitudes de dichas variaciones resultan a su vez muy influenciadas por el tipo de cemento utilizado, aun siendo de la misma clase resistente.

  5. 29 CFR 1926.703 - Requirements for cast-in-place concrete.

    Science.gov (United States)

    2010-07-01

    ... to support loads in excess of its capacity. (c) Vertical slip forms. (1) The steel rods or pipes on... paragraph. (2) Drawings or plans, including all revisions, for the jack layout, formwork (including shoring... erection to determine that the equipment meets the requirements specified in the formwork drawings....

  6. Static and cyclic pullout behavior of cast-in-place headed and bonded anchors with large embedment depths in cracked concrete

    Energy Technology Data Exchange (ETDEWEB)

    Delhomme, F., E-mail: fabien.delhomme@insa-lyon.fr [University of Lyon, INSA-Lyon, LGCIE, F-69621 Villeurbanne (France); Roure, T.; Arrieta, B. [EDF SEPTEN Compagny, Civil Engineering, Villeurbanne (France); Limam, A. [University of Lyon, INSA-Lyon, LGCIE, F-69621 Villeurbanne (France)

    2015-06-15

    Highlights: • Optimizing the design and identifying margin of the headed fasteners used in French nuclear power plants. • Static and cyclic pullout tests on cast in place anchorage composed of an anchor plate welded to four headed or bonded rods. • Experimental data base on tests on anchor plates. • Anchor with large embedment depths in cracked concrete. • Edge effects. - Abstract: The equipment of French nuclear power plants is fixed on reinforced concrete structures with base plate with headed fasteners. EDF decided to carry out an experimental research program in partnership with LGCIE in order to optimize the design of the headed fasteners and identify margin. This article introduces the results of pullout tests on anchors with large embedment cast in place in a reinforced concrete block. The anchorage are composed of an anchor plate welded to four ribbed bars or headed smooth studs. The studied parameters are: the type of loading (static or cyclic), the edge distance, the state of cracking of the concrete block. The anchors with headed rods or ribbed bars have a steel rod failure mode in agreement with their initial design. However, an optimization of the size on the headed anchors seems to be expected in order to improve their installation. This experimental campaign will provide a data base enabling the development of numerical models in order to improve the design.

  7. Static and cyclic pullout behavior of cast-in-place headed and bonded anchors with large embedment depths in cracked concrete

    International Nuclear Information System (INIS)

    Highlights: • Optimizing the design and identifying margin of the headed fasteners used in French nuclear power plants. • Static and cyclic pullout tests on cast in place anchorage composed of an anchor plate welded to four headed or bonded rods. • Experimental data base on tests on anchor plates. • Anchor with large embedment depths in cracked concrete. • Edge effects. - Abstract: The equipment of French nuclear power plants is fixed on reinforced concrete structures with base plate with headed fasteners. EDF decided to carry out an experimental research program in partnership with LGCIE in order to optimize the design of the headed fasteners and identify margin. This article introduces the results of pullout tests on anchors with large embedment cast in place in a reinforced concrete block. The anchorage are composed of an anchor plate welded to four ribbed bars or headed smooth studs. The studied parameters are: the type of loading (static or cyclic), the edge distance, the state of cracking of the concrete block. The anchors with headed rods or ribbed bars have a steel rod failure mode in agreement with their initial design. However, an optimization of the size on the headed anchors seems to be expected in order to improve their installation. This experimental campaign will provide a data base enabling the development of numerical models in order to improve the design

  8. On prevention of cast-in-place concrete floor cracks%现浇混凝土楼板裂缝的防治

    Institute of Scientific and Technical Information of China (English)

    吕学刚

    2009-01-01

    分析了现浇混凝土楼板裂缝产生的原因,探讨了楼板裂缝产生的危害,并提出了现浇楼板裂缝的控制措施和弥补处理措施,以有效遏制楼板裂缝,从而提高建筑物的工程质量.%The paper analyzes reasons for cracks on floor of east-in-place concrete, explores the damage of the cracks on the floor, and points out some control measures and repairing treatment of the cast-in-place concrete floor, so as to check the floor cracks effectivdy and to improve the project quality of building.

  9. The Application of F ine-aggregate Concrete in the Cast-in-place Prestressed Concrete Hollow Slab%细石混凝土在现浇预应力空心楼板结构中的应用

    Institute of Scientific and Technical Information of China (English)

    刘维忠

    2015-01-01

    本文主要介绍了 C40细石混凝土在现浇预应力空心楼板工程实例中的应用,有效解决了预应力空心楼板结构浇筑时泵送难度大、钢筋间距小、填充困难等施工难点,并且通过原材料控制、混凝土生产过程控制、施工现场控制等措施保证 C40细石混凝土的顺利浇筑。经后期检测,满足预应力张拉要求,应用效果理想。%This paper mainly introduced the application of C40 fine-aggregate concrete in the Cast-in-place prestressed concrete hollow slab, the application effectively solved a series of construction difficulties such as small bar spacing, difficult pumping and filling. By taking measures of controlling the quality of materials, concrete production process and the construction site to realize the smooth casting of C40 fine-aggregate concrete. After the later detection, this concrete met the requirements of prestressed tensioning and the application effect proved to be ideal.

  10. 现浇钢筋混凝土楼板裂缝处理分析%The Cast-in-place Reinforced Concrete Floor Crack Analysis

    Institute of Scientific and Technical Information of China (English)

    林海滨

    2013-01-01

    This paper combined with the specific engineering examples, analyzes the reasons caused the cracks on cast-in-p-lace reinforced concrete floor search, and puts forward the me-thod of crack treatment, which to offer a reference for similar engineering treatment.%文章结合具体工程实例,对现浇钢筋混凝土楼板裂缝产生原因的查找进行了分析,并提出了裂缝处理方法,可为类似工程处理提供参考。

  11. Design and Analysis of Cast-in-place Concrete Hollow Floor%现浇混凝土空心楼盖的设计与分析

    Institute of Scientific and Technical Information of China (English)

    卢宇航

    2014-01-01

    经济的不断发展,使得我国的建筑行业得到了更好的发展。本文通过工程实例,分析比较了采用现浇混凝土空心楼盖和实心楼盖的工程量和造价,阐述了空心楼盖特点及优势,并对空心楼盖的设计要点进行了分析。%The unceasing development of economy, makes our country's construction industry has a bet er development. This paper through the engineering examples, analyzes the project volume and cost of cast-in-situ concrete hol ow floor and solid floor, expounds the characteristics and advantages of hol ow floor, and analyzes the key design points of hol ow floor.

  12. 论泵送混凝土现浇板裂缝产生机理及预防措施%Study on the mechanism caused the cracks in cast-in-place floor of pump concrete and preventive measures

    Institute of Scientific and Technical Information of China (English)

    许洪祥

    2009-01-01

    针对泵送混凝土现浇板产生的各种裂缝,从混凝土组成、搅拌、运输、泵送、浇筑、养护、支模等方面出发,通过对各生产环节的观察和试验,对裂缝产生的机理进行了深入、全面地分析,并针对不同问题提出了相应的预防措施,以减少或避免出现混凝土裂缝.%According to various cracks produced in cast-in-place floor of pump concrete, from the composition, mixing, transportation, pumping, pouring, curing and other aspects the mechanism caused the production of those cracks in cast-in-place floor of pump concrete are comprehensively analyzed based upon observation and experiments, at the same time corresponding preventive measures are proposed, in order to reduce and eliminate the production of those cracks in pump concrete.

  13. 钢筋混凝土现浇楼板裂缝原因分析与治理%On analysis of reasons for cracks on reinforced concrete cast-in-place floors and treatment

    Institute of Scientific and Technical Information of China (English)

    吕海亭

    2016-01-01

    结合工作经验,分析了钢筋混凝土现浇楼板裂缝发生的原因,从设计、材料、施工等方面,阐述了治理钢筋混凝土现浇楼板裂缝的对策,旨在提高现浇楼板的施工质量,保证建筑结构的安全性。%Combining with work experience,the paper analyzes the reasons for the cracks on reinforced concrete cast-in-place floors,and illus-trates the strategies for the treatment of the cracks on the floors from the design,materials,and construction,so as to improve the construction quality of the cast-in-place floors and ensure the safety of the architectural structure.

  14. Effect of Pour Size on Concrete Placing Productivity in Nigeria

    OpenAIRE

    Olaoluwa Olatunde; Ojo Stephen Okunlola; Adesanya David Abiodun

    2012-01-01

    Pour size as one of the site factors affecting concreting was examined to determine its effects on concreting productivity. A total of 167 separate concrete pours were observed on 25 building construction sites in Lagos, Nigeria,comprising 35 pours placed by crane and skip; 26 pours placed by dumper; 58 pours placed by wheelbarrow; 37 pours placed by head pan; and 11 pours placed jointly by pump, wheelbarrow and head pan. Data collected from the daily concrete pours were analyzed to determine...

  15. Quality defects and prevention measures of cast-in-place reinforced concrete%浅谈现浇钢筋混凝土质量通病及防治措施

    Institute of Scientific and Technical Information of China (English)

    金国尧

    2014-01-01

    Cast-in-place reinforced concrete is used more and more widely in constructional engineering,thus ensuring the construction quality is very important.This paper analyzes causes and prevention measures of quality defects of reinforced concrete, such as cracks,cellular,pockmarked face,holes,exposed tendons and so on.%现浇钢筋混凝土施工在建筑工程中应用越来越广泛,因此,保证其工程质量很重要。文章分析了钢筋混凝土裂缝、蜂窝、麻面、孔洞、露筋等质量通病产生的原因及其防治措施。

  16. Analysis and Prevention about the Causes of Cracks on the Reinforced Concrete Cast-in-Place Floor Slab%混凝土现浇楼板裂缝的分析与防控

    Institute of Scientific and Technical Information of China (English)

    王振平

    2015-01-01

    In high-rise residential buildings,reinforced concrete frame cast-in-place reinforced concrete floor slab was widely used. But it was found that cracks often appeared in use of cast-in-place floor slab, cracks had brought many adverse effects to the unit and the owners. Aiming at the phenomenon,this paper analyzed the crack causes and proposed prevention and control measures.%在高层住宅建筑中,钢筋混凝土框架及钢筋混凝土现浇楼板被广泛采用。但在使用中发现,现浇楼板常出现裂缝,裂缝的产生给使用单位和业主带来了诸多不利影响。针对该现象,分析现浇楼板裂缝成因,并提出防控措施。

  17. On analysis of cracks of cast-in-place concrete buildings' floors and its prevention measures%现浇混凝土楼板裂缝的原因分析和防治措施

    Institute of Scientific and Technical Information of China (English)

    魏英歌

    2012-01-01

    According to the cracks on the cast-in-place concrete buildings floors the common phenomenon,the paper analyzes the factors,including the construction,the design and materials by combining with the many-year experience and lessons from the construction practice,locates the comprehensive reasons for the floor cracks,and points out some factual prevention measures,so as to improve the construction quality of the cast-in-place floors.%针对现浇楼板裂缝这一十分普遍的现象,本文结合多年来在施工实践中的经验和教训,重点分析以施工为主、兼顾设计和材料等几方面的因素,找出楼面裂缝的综合性原因,并提出一些具体防治措施,以提高现浇楼板施工质量。

  18. 论现浇钢筋混凝土空心楼盖施工工艺%Construction Techniques of Hollow Cast-in-place Reinforced Concrete Floors

    Institute of Scientific and Technical Information of China (English)

    杨振山

    2012-01-01

    The project,the transformation of the underground garage in an urban village,covering 50,000 square meters,adopts the hollow cast-in-place reinforced concrete floor promoted by the Ministry of Construction as chief scientific and technological achievements for its floor and the national green material,high-strength light mandrel,which saves lots of concrete and reduces the weight of the floor with a cost reduction by 13 percent.%本工程为某城中村改造地下车库项目,建筑面积为5万m2,地下车库楼板采用建设部科技成果重点推广的现浇钢筋混凝土空心楼盖技术,采用国家推行的绿色建筑材料———高强度轻质芯模。为工程节省了大量的混凝土,减轻了楼板的重量,工程造价节约13%。

  19. 现浇混凝土楼板裂缝的质量控制%On quality control 0f construction crack in cast-in-place concrete floor

    Institute of Scientific and Technical Information of China (English)

    汪志勇

    2011-01-01

    Cracks occurred on the floor through the understanding and analysis of the site,as well as to introduce cracks in the floor structure of the impact of construction for cast-in-place concrete floor construction of the causes of cracks are analyzed,from the%本文通过对楼板裂缝发生部位分析以及楼板裂缝对建筑结构造成的影响入手,针对现浇混凝土楼板施工裂缝产生的原因进行了分析,从优化混凝土配合比、改善养护工艺、规范施工操作规程、控制温度梯度变化等方面探讨了裂缝控制措施,最后介绍了裂缝的处理方法,以解决好裂缝问题,提高工程质量。

  20. Effect of Pour Size on Concrete Placing Productivity in Nigeria

    Directory of Open Access Journals (Sweden)

    Olaoluwa Olatunde

    2012-06-01

    Full Text Available Pour size as one of the site factors affecting concreting was examined to determine its effects on concreting productivity. A total of 167 separate concrete pours were observed on 25 building construction sites in Lagos, Nigeria,comprising 35 pours placed by crane and skip; 26 pours placed by dumper; 58 pours placed by wheelbarrow; 37 pours placed by head pan; and 11 pours placed jointly by pump, wheelbarrow and head pan. Data collected from the daily concrete pours were analyzed to determine operational productivity rates. The relationship between concreting productivity and pour size was examined using regression analyses to develop a model relating productivity to pour size. The results showed that irrespective of placing method, productivity generally increased by 1.1 m3/h for every 10 m3 increase in pour size. It was recommended that the obtained index of productivity increase per pour size be standardised for use in improving on-site productivity in the Nigerian construction industry.

  1. Construction Quality Control of Cast-in-place Concrete Hollow Floor with GBF Pipe%GBF管现浇混凝土空心楼板施工质量控制探讨

    Institute of Scientific and Technical Information of China (English)

    黄绍斌

    2014-01-01

    This paper according to the author's practices, co-mbined with an example of a GBF cast-in-situ hol ow floor engineering, with reference to the correlation datas, carries on the discussion to the cast-in-situ concrete hol ow floor with GBF pipe from the key point, technical construction measures, quality control, quality standards and so on.%本文主要根据笔者多年的工作实践,结合某 GBF现浇空心楼盖工程实例,并参考了相关资料,对现浇 GBF管混凝土空心楼板在技术关键点、构造措施、质量控制、质量标准等方面进行探讨。

  2. High capacity cast-in-place concrete pile load tests at CNRL's oil sand plant near Fort McMurray, Alberta

    Energy Technology Data Exchange (ETDEWEB)

    Clementino, R.; Tweedie, R.; Sobkowicz, J.; Workman, C. [Thurber Engineering Ltd., Calgary, AB (Canada); Sisson, R. [Canadian Natural Resources Ltd., Calgary, AB (Canada)

    2006-07-01

    In order to assess capacities for design of foundation piles, a thorough pile load test program was conducted in 2003 and 2004 at Canadian Natural Resources Limited's (CNRL) Horizon Oil Sands Plant site, located near Fort McMurray, Alberta. One of its major components is a large plant for the extraction and upgrading of bitumen from oil sand. The program consisted of five piles tested in a static frame to vertical loads of up to 10 MN, four piles tested using the statnamic method to loads of up to 16 MN, and two piles tested using Osterberg Cells at equivalent top-down loads of up to 22 MN. This paper described the installation and instrumentation of the piles and presented the test results. It also compared these results to historical design values and discussed the results. It was concluded that the pile load test program demonstrated that high capacity can be achieved with straight shaft piles that extend 6 metres or more into oil sands, with small settlements. Piles may be designed using a combination of shaft friction and end bearing capacity. In many instances, end bearing capacity can be ignored, requiring less base preparation and inspection. 6 refs., 2 tabs., 11 figs.

  3. EXPERIMENTAL STUDIES ON ASEISMIC PERFORMANCE OF T-SHAPE FABRICATED CONCRETE JOINTS WITH PRECAST EXTERNAL SHELL AND CAST-IN-PLACE CORE CONCRETE%外壳预制核心现浇装配式T型钢筋混凝土节点抗震性能试验研究

    Institute of Scientific and Technical Information of China (English)

    张大长; 郭雁; 李布辉

    2013-01-01

    In order to investigate the aseismic performance of fabricated concrete T-shape exterior RC joint with precast external shells and cast-in-place core, one new-type assembled exterior joint and one parallel joint were fabricated, and cyclic loading tests of the T-shape joints were carried out. The aseismic performances were investigated, including failure modes, hysteretic property, ductility, energy dissipation, stiffness degradation. The studies showed that the new-type assembled T-joint had excellent integrity and aseismic performance, similar to those of the cast-in-place RC T-joint, and could meet the aseismic-design requirement of RC frame structure.%该文以研究外壳核心现浇预制装配式钢筋混凝土T型边节点的抗震性能为目的,制作一个新型装配式边节点和一个现浇边节点,开展两个T型节点抗震性能的低周反复试验,考察并分析比较采用两种不同施工方法的T型边节点的破坏形态、滞回特性、位移延性、能量耗散、刚度退化等抗震性能,研究表明新型装配式T型节点与RC现浇T型节点相似,具有良好的整体性和抗震性能,可以满足RC框架结构的抗震设计要求.

  4. Discussion on improving cast-in-place concrete ribbed beam hollow floor with GBF honeycomb core construction technology%提高 GBF 蜂巢芯现浇混凝土密肋梁空心楼盖施工技术的探讨

    Institute of Scientific and Technical Information of China (English)

    张世明

    2015-01-01

    GBF蜂巢芯现浇混凝土密肋梁空心楼盖是一种新型的楼盖结构。本文从一个工程实例出发,介绍了蜂巢芯安装及相应的技术措施,详细介绍了提高其施工质量的模板、钢筋、混凝土技术措施。%Cast-in-place concrete ribbed beams hollow floor with GBF honeycomb core is a new type of floor structure.Based on an en-gineering example, this paper introduces the installation of honeycomb core and corresponding technical measures ,and the template, steel bar and concrete technical measures was introduced in detail to improve the quality of its construction.

  5. Entire cast-in-place concrete lfoor (top) analysis of the causes and prevention of cracks in the system cover%混凝土整体现浇楼(顶)盖裂缝的成因分析和系统预防

    Institute of Scientific and Technical Information of China (English)

    徐智尧

    2015-01-01

    在房屋建筑工程中,混凝土整体现浇楼盖的使用非常广泛。但混凝土整体现浇楼盖裂缝往往会引起投诉、纠纷以及索赔要求等,因此裂缝是混凝土工程中普遍存在的问题,这就要求我们对此予以足够的重视。本文主要就混凝土整体现浇楼盖出现裂缝的原因以及进行系统预防的具体措施进行了分析研究。%In building engineering, concrete pouring the whole floor is widely used. But the entire cast-in-place concrete floor cracks often give rise to complaints, disputes and claims, so the concrete crack is a common problem in the engineering, which requires us to pay enough attention to. This paper mainly embodies the specific measures of pouring concrete whole floor cracks causes and prevention system is studied.

  6. Lightweight Concrete Produced Using a Two-Stage Casting Process

    Directory of Open Access Journals (Sweden)

    Jin Young Yoon

    2015-03-01

    Full Text Available The type of lightweight aggregate and its volume fraction in a mix determine the density of lightweight concrete. Minimizing the density obviously requires a higher volume fraction, but this usually causes aggregates segregation in a conventional mixing process. This paper proposes a two-stage casting process to produce a lightweight concrete. This process involves placing lightweight aggregates in a frame and then filling in the remaining interstitial voids with cementitious grout. The casting process results in the lowest density of lightweight concrete, which consequently has low compressive strength. The irregularly shaped aggregates compensate for the weak point in terms of strength while the round-shape aggregates provide a strength of 20 MPa. Therefore, the proposed casting process can be applied for manufacturing non-structural elements and structural composites requiring a very low density and a strength of at most 20 MPa.

  7. Refreezing of cast-in-place piles under various engineering conditions

    Institute of Scientific and Technical Information of China (English)

    Lei Guo; QiHao Yu; XiaoNing Li; XinBin Wang; YongYu Yue

    2015-01-01

    In the construction of the Qinghai-Tibet Power Transmission Line (QTPTL), cast-in-place piles (CIPPs) are widely applied in areas with unfavorable geological conditions. The thermal regime around piles in permafrost regions greatly affects the stability of the towers as well as the operation of the QTPTL. The casting of piles will markedly affect the thermal regime of the surrounding permafrost because of the casting temperature and the hydration heat of cement. Based on the typical geological and engineering conditions along the QTPTL, thermal disturbance of a CIPP to surrounding permafrost under different casting seasons, pile depths, and casting temperatures were simulated. The results show that the casting season (summer versus winter) can influence the refreezing process of CIPPs, within the first 6 m of pile depth. Sixty days after being cast, CIPPs greater than 6 m in depth can be frozen regardless of which season they were cast, and the foundation could be refrozen after a cold season. Comparing the refreezing characteristics of CIPPs cast in different seasons also showed that, without considering the ground surface conditions, warm seasons are more suitable for casting piles. With the increase of pile depth, the thermal effect of a CIPP on the surrounding soil mainly expands vertically, while the lateral heat disturbance changes little. Deeper, longer CIPPs have better stability. The casting temperature clearly affects the thermal disturbance, and the radius of the melting circle increases with rising casting temperature. The optimal casting temperature is between 2 °C and 9 °C.

  8. An improvement of design criteria for cast-in place anchor

    International Nuclear Information System (INIS)

    Actual model tests are carried out to examine the appropriateness of design criteria that is available for the anchorage design in this study. These tests are intended for the cast-in-place anchor that is widely used for the fastening of equipment in Korean NPPs. 35 test specimens taking account of 7 test conditions are manufactured on a basis of ASTM E488 under non-cracked and plain concrete for these actual model tests. As principal test variables, effective anchor embedment depth, anchor with edge effects, and anchor with overlapping failure volume etc. are chosen. In order to apply the tensile force, 100 tonf-capacity actuator is used with displacement control of 0.5 mm/min. It is proved that ACI 349-01 and CCD procedure of CEB- FIP Code are very conservative against test results through these actual model tests and the improved design criterion is proposed on a basis of test results in order to better the economical efficiency of NPPs in this study

  9. An Analysis of Factors Enhancing the Durability of Cast-in-place Concrete%提升现浇混凝土耐久性的相关因素分析

    Institute of Scientific and Technical Information of China (English)

    沈玉君

    2015-01-01

    文章将会从优选原材料与质量控制体系,高性能混凝土配台比设计体系,钢筋保护层施工质量控制体系以及混凝土施工质量控制及反馈体系这四个方面分别加以阐述,希望能够得到一些借鉴和参考。%This paper would expound from the optimization of raw materials and quality control system, mix design system of high performance concrete ,construction quality control system of reinforced cover and control and feedback system of concrete construction quality, hoping to provide some reference for all.

  10. Life Cycle Assessment of IBS in Malaysia and Comparing Human Health on Timber and Concrete Pre-cast

    Directory of Open Access Journals (Sweden)

    Ali Tighnavard Balasbaneh

    2013-12-01

    Full Text Available The aim of this study is determining the life cycle assessment of IBS and compares the environmental impacts of building. There are two different kinds of structure has been assessed in this project namely: Timber prefabricate and concrete pre-cast. IBS is a prefabricated structure which component manufacturing in the factory and then transfer to site work for erect. Timbers prefabricate and concrete pre-cast is compared from the initial stage of extracting material to end of life. The method of LCIA in the project is Impact 2002. This project reveals that the total environmental impact of Timber prefabricated is lower than concrete pre-cast in both manufacturing and use phase 100 year life cycle of IBS. Secondly global warming and ozone layer depletion emissions from timber are also much lower than concrete.

  11. A method for the realization of complex concrete gridshell structures in pre-cast concrete

    DEFF Research Database (Denmark)

    Larsen, Niels Martin; Egholm Pedersen, Ole; Pigram, Dave

    2012-01-01

    This paper describes a method for the design and fabrication of complex funicular structures from discrete precast concrete elements. The research proposes that through the integration of digital form finding techniques, computational file-to-fabrication workflows and innovative sustainable concr...

  12. 均匀黏弹性地基中现浇 X 形桩低应变动测响应数值模拟%Numerical Simulation of Low Strain Dynamic Test Response for X-section Cast-in-place Concrete Pile on Homogeneous Viscoelastic Foundation

    Institute of Scientific and Technical Information of China (English)

    范玉明; 丁选明; 朱振生; 付强

    2015-01-01

    A three dimensional finite model of an X-section cast-in-place concrete pile-soil system is established to simulate wave propagation in a low strain integrity X-section cast-in-place concrete pile (XCC pile).Velocity responses in the time domain at the top of the intact and defective piles are obtained.The velocity response characteristics of the intact pile are analyzed in addition to the velocity response curves of the defective piles.The results reveal that the velocity response at the top of the XCC pile during low strain integrity testing shows serious 3D effects,resulting in the peak value of the incident wave close to the pile center being largest,and the arrival time of the peak value of the incident wave close to the pile center being earliest.The farther a point is from the pile center,the more hysteretic is the peak of the arriving incident wave.The peak value of the incident waves first increases and then reduces from the pile center to the pile boundary.The inci-dent and reflected waves at different points along the ring direction at the top of the intact pile are very similar,but the disturbing waves of different points are not the same.The arrival time of the incident waves in the pile with variable modulus are the same as those in the intact pile,but the arrival time of the peak of the reflection wave at the bottom of the pile with variable modulus is later than that in the intact pile,and the peak value is smaller.The first defective reflected waves at different points along ring direction at the top of the defective XCC pile shows little differ-ences,but the second one shows larger differences.%建立现浇 X 形桩(XCC 桩)桩-土体系三维有限元模型,对 XCC 桩低应变检测动力响应进行数值模拟,得到完整桩和缺陷桩的桩顶速度响应结果,并分析完整桩及缺陷 XCC 桩桩顶速度响应特性及规律。计算结果表明:XCC 桩低应变瞬态动测时桩顶速度响应存在明显的三维效应,桩

  13. Experimental Research on Large Diameter Cast-in-Place Piles Embedded in Rock

    Institute of Scientific and Technical Information of China (English)

    衡朝阳; 何满潮; 姚爱军

    2001-01-01

    This paper expatiated the field test of large diameter cast-in-place piles embedded in soft rock, including static loading test, high or low strain dynamic test, measurement of stresses and strains of pile body, and pressure measurements between pile tip and soft rock. The relative in-situ test problems are discussed. Based on the limit equilibrium theory and the load transfer equation, a synthesis method of analyzing the ultimate carrying capacity of single large diameter pile is put forward. The research results show that the key to determining the ultimate carrying capacity of single pile with a large diameter is the analysis of the intensity of soft rock.

  14. 现浇砼聚苯乙烯BDF柱体施工%The Cast-in-situ Concrete Polystyrene BDF Column Construction

    Institute of Scientific and Technical Information of China (English)

    范海军; 范佳波

    2012-01-01

      现浇混凝土空心楼盖技术是建筑结构领域的一项创新,符合人类的高技术水平的建筑结构体系。本文根据瑞景国际地下车库现浇砼空心楼盖工程对施工现场的管理、BDF 聚苯轻质柱体质量要求和施工技术进行阐述,为类似现浇混凝土空心楼盖施工提供技术参考。%  Cast-in-situ concrete hol ow floor system technol-ogy is an innovation in the field of building structure. It is in line with the human high technology of building structure system.In this paper, the author elaborates construction site management,quality requirements of the BDF polystyrene light column and construction technology about cast-in-situ concre-te hol ow floor engineering of the vista international underg-round garage, in order to provide technical reference for sim-ilar cast-in-place concrete hol ow floor construction.

  15. Stay-in-Place Formwork of TRC Designed as Shear Reinforcement for Concrete Beams

    OpenAIRE

    Verbruggen, S; Remy, O.; J. Wastiels; Tysmans, T.

    2013-01-01

    In order to reduce on-site building time, the construction industry shows an increasing interest in stay-in-place formwork with a reinforcement function after concrete hardening, such as CFRP formwork confinement for columns. The current combined systems however do not answer the demand of the building industry for a material system that is both lightweight and fire safe. High performance textile reinforced cement (TRC) composites can address this need. They can be particularly interesting fo...

  16. Stay-in-Place Formwork of TRC Designed as Shear Reinforcement for Concrete Beams

    Directory of Open Access Journals (Sweden)

    S. Verbruggen

    2013-01-01

    Full Text Available In order to reduce on-site building time, the construction industry shows an increasing interest in stay-in-place formwork with a reinforcement function after concrete hardening, such as CFRP formwork confinement for columns. The current combined systems however do not answer the demand of the building industry for a material system that is both lightweight and fire safe. High performance textile reinforced cement (TRC composites can address this need. They can be particularly interesting for the shear reinforcement of concrete beams. This paper describes a preliminary analysis and feasibility study on structural stay-in-place formwork made of TRC. Comparative bending experiments demonstrate that a fully steel reinforced beam and an equivalent beam with shear reinforcement in TRC formwork show similar yielding behaviour, indicating that the TRC shear reinforcement system actually works. Moreover, the cracking moment of the concrete was more or less doubled, resulting in a much lower deflection in serviceability limit state than calculated. Digital image correlation measurements show that the latter is due to the crack bridging capacity of the external TRC shear reinforcement.

  17. Optimization of Casting Process Parameters for Homogeneous Aggregate Distribution in Self-Compacting Concrete: A Feasibility Study

    DEFF Research Database (Denmark)

    Spangenberg, Jon; Tutum, Cem Celal; Hattel, Jesper Henri;

    2011-01-01

    The use of self-compacting concrete (SCC) as a construction material has been getting more attention from the industry. Its application area varies from standard structural elements in bridges and skyscrapers to modern architecture having geometrical challenges. However, heterogeneities induced...... during the casting process may lead to variations of local mechanical properties and hence to a potential decrease in load carrying capacity of the structure. This paper presents a methodology for optimization of SCC casting aiming at having a homogeneous aggregate distribution; a beam has been used...... as geometric example. The aggregate distribution is predicted by a numerical flow model coupled with a user defined volume fraction subroutine. The process parameters in casting with SCC in general are horizontal and vertical positions, movement, as well as the size of the inlet, and the duration...

  18. 现浇门架设计与施工%On Design and Construction of Cast-in-place Gantry

    Institute of Scientific and Technical Information of China (English)

    陈艳茹; 杨勃

    2012-01-01

    随着交通结构的多样化发展,立体交通格局的全面布置,跨线桥数量越来越多。临时支撑结构中的现浇门架设计是现行有效解决现浇跨线桥施工与既有线之间矛盾的方法,本文结合经开区特大桥跨合武铁路连续梁现浇门架施工实例,说明现浇门架的设计与施工要点,可供同类工程借鉴。%With the development of traffic structure diversification and the overall layout of three-dimensional transportation pattern,more and more overpass bridges appear in different places.The cast-in-place gantry design,one of the temporary support structures,is an effective so lution to resolve the contradiction between the cast-in-place overpass construction and the existing line.This paper,combining the example of constructing successive cast-in-place gantries in the big overpass across the Hewu railway in Jingkai Area,explains the design and construction of cast-in-place gantries,which can provide reference for similar projects.

  19. Automatic dam concrete placing system; Dam concrete dasetsu sagyo no jidoka system

    Energy Technology Data Exchange (ETDEWEB)

    Yoneda, Y.; Hori, Y.; Nakayama, T.; Yoshihara, K.; Hironaka, T. [Okumura Corp., Osaka (Japan)

    1994-11-15

    An automatic concrete placing system was developed for concrete dam construction. This system consists of the following five subsystems: a wireless data transmission system, an automatic dam concrete mixing system, a consistency determination system, an automatic dam concrete loading and transporting system, and a remote concrete bucket opening and closing system. The system includes the following features: mixing amount by mixing ratio and mixing intervals can be instructed from a concrete placing site by using a wireless handy terminal; concrete is mixed automatically in a batcher plant; a transfer car is started, and concrete is charged into a bucket automatically; the mixed concrete is determined of its properties automatically; labor cost can be reduced, the work efficiency improved, and the safety enhanced; and the system introduction has resulted in unattended operation from the aggregate draw-out to a bunker line, manpower saving of five persons, and reduction in cycle time by 10%. 11 figs., 2 tabs.

  20. Development of NZP ceramic based {open_quotes}cast-in-place{close_quotes} diesel engine port liners

    Energy Technology Data Exchange (ETDEWEB)

    Nagaswaran, R.; Limaye, S.Y.

    1996-02-01

    BSX (Ba{sub 1+x}Zr{sub 4}P{sub 6-2x}Si{sub 2x}O{sub 24}) and CSX (Ca{sub l-x}Sr{sub x}Zr{sub 4}P{sub 6}O{sub 24}) type NZP ceramics were fabricated and characterized for: (i) thermal properties viz., thermal conductivity, thermal expansion, thermal stability and thermal shock resistance; (ii) mechanical properties viz., flexure strength and elastic modulus; and (iii) microstructures. Results of these tests and analysis indicated that the BS-25 (x=0.25 in BSX) and CS-50 (x=0.50 in CSX) ceramics had the most desirable properties for casting metal with ceramic in place. Finite element analysis (FEA) of metal casting (with ceramic in place) was conducted to analyze thermomechanical stresses generated and determine material property requirements. Actual metal casting trials were also conducted to verify the results of finite element analysis. In initial trials, the ceramic cracked because of the large thermal expansion mismatch (hoop) stresses (predicted by FEA also). A process for introduction of a compliant layer between the metal and ceramic to alleviate such destructive stresses was developed. The compliant layer was successful in preventing cracking of either the ceramic or the metal. In addition to these achievements, pressure slip casting and gel-casting processes for fabrication of NZP components; and acoustic emission and ultrasonics-based NDE techniques for detection of microcracks and internal flaws, respectively, were successfully developed.

  1. 现浇混凝土空心楼盖在工程中的应用%Cast-in-situ Concrete Hollow Floor Slab in Engineering Application

    Institute of Scientific and Technical Information of China (English)

    潘向军; 王守君; 张静芳

    2012-01-01

    介绍了现浇混凝土空心楼盖结构体系的特点及设计思路和方法,并结合某地下停车场工程的设计实例,说明了现浇混凝土空心楼盖技术在工程中的应用.%This paper introduces the cast-in-situ concrete hollow floor structure system characteristic and its design ideas and methods. Combining some underground parking garage engineering design examples籺he cast-in-situ concrete hollow floor technique apply in the project is illustrated.

  2. Concrete strain gage in concrete shaft lining: Installation and monitoring procedure: Final draft

    International Nuclear Information System (INIS)

    A cast-in-place concrete or concrete block preliminary lining component and a cast-in-place final concrete lining form part of the shaft lining system. Strain measurements within the cast-in-place concrete linings will be obtained using a concrete strain gage (CSG). This gage consists of a vibrating wire sensor and anchors embedded in the concrete during casting CSGs will be installed in both exploratory shafts. The primary objective of the overall monitoring program, of which these gages constitute one part, is to define the stress-deformation behavior of the shaft lining, seals, and foundations during and after construction. For this purpose it is necessary to consider the CSG embedded in the concrete as one element of an integrated program of monitoring the mechanical and thermomechanical response of the shaft. Other instruments that form part of this program include concrete stress meters, steel strain gages on the steel shaft liner, convergence gages, piezometers, joint meters, bitumen pressure gages, temperature detectors, and extensometers. For a justification and basis for design of the instrument arrays which form part of the Shaft Mechanical and Thermal Response Monitoring, refer to the Draft Shaft Study Plan. 8 figs

  3. Design Analysis on the Cement Concrete Mix Ratio of C30 Underwater Cast-in-place Pile with Anti-rust Agent%加阻锈剂的C30水下灌注桩水泥混凝土配合比设计分析

    Institute of Scientific and Technical Information of China (English)

    郝丽

    2015-01-01

    随着我国交通事业的快速发展,水泥混凝土配合比设计在高等级公路和地方公路大中小桥的施工中占有越来越重要的地位.本文针对氯离子含量超标地区的桥梁施工中水泥混凝土配合比设计进行了论述,为类似桥梁施工进行水泥混凝土配合比设计提供了一些借鉴和参考.%With the rapid development of China's transportation industry, cement concrete mix ratio design in the con-struction of large, medium, and small bridges in high-grade highway and local highway occupies an increasingly im-portant position. In this paper, the design of cement concrete mix ratio in bridge construction in the area of excessive chloride content is discussed, which provides some references for the design of cement concrete mix ratio for similar bridge construction.

  4. Seismic performance analysis and design suggestion for frame buildings with cast-in-place staircases

    Science.gov (United States)

    Feng, Yuan; Wu, Xiaobin; Xiong, Yaoqing; Li, Congchun; Yang, Wen

    2013-06-01

    Many staircases in reinforced concrete (RC) frame structures suffered severe damage during the Wenchuan earthquake. Elastic analyses for 18 RC structure models with and without staircases are conducted and compared to study the influence of the staircase on the stiffness, displacements and internal forces of the structures. To capture the yielding development and damage mechanism of frame structures, elasto-plastic analysis is carried out for one of the 18 models. Based on the features observed in the analyses, a new type of staircase design i.e., isolating them from the master structure to eliminate the effect of K-type struts, is proposed and discussed. It is concluded that the proposed method of staircase isolation is effective and feasible for engineering design, and does not significantly increase the construction cost.

  5. Analysis on the application of cast-in-situ concrete hollow floors%现浇混凝土空心楼盖的应用分析

    Institute of Scientific and Technical Information of China (English)

    孔鹏

    2011-01-01

    针对现浇钢筋混凝土空心板无梁楼盖进行了简要介绍,阐述了空心板无梁楼盖的受力机理,通过其受力分析,指出现浇混凝土空心楼板受力性能符合双向板受力理论,应根据受力情况合理确定配筋方式,并在柱帽设计时进行受剪计算。%This paper briefly introduces the cast-in-situ reinforced concrete hollow girderless floors, and describes the force mechanism of the hollow girderless floor, and then points out that the force property of cast-in-situ concrete hollow floors conforms to t

  6. 声波透射法在灌注桩检测中的应用研究%Explore the Application of Acoustic Wave Transmission Method in the Cast-in-place Pile Detection

    Institute of Scientific and Technical Information of China (English)

    郑育成

    2014-01-01

    The acoustic wave transmission method use the acoustic principle, which means through the spread of acoustic wave at enuation degree in concrete to determine if the cast-i-n-place pile is complete or not, so as to determine the constr-uction quality of cast-in-place pile. Therefore, this article carr-ies on the detailed research and analysis of the application of acoustic wave transmission method in the cast-in-place pile de-tection.%声波透射法利用声学原理,也就是通过声波在混凝土这种介质中传播的衰减程度来确定灌注桩的桩身是否完整,从而确定灌注桩的施工质量。因此,本文就对声波透射法在灌注桩检测中的应用进行了详细的研究和分析。

  7. Numerical investigation of soil plugging effect inside sleeve of cast-in-place piles driven by vibratory hammers in clays.

    Science.gov (United States)

    Xiao, Yong Jie; Chen, Fu Quan; Dong, Yi Zhi

    2016-01-01

    During driving sleeve of cast-in-place piles by vibratory hammers, soils were squeezed into sleeve and then soil plugging was formed. The physic-mechanical properties of the soil plug have direct influence on the load transmission between the sleeve wall and soil plug. Nevertheless, the researches on this issue are insufficient. In this study, finite element and infinite element coupling model was introduced, through the commercial code ABAQUS, to simulate the full penetration process of the sleeve driven from the ground surface to the desired depth by applying vibratory hammers. The research results indicated that the cyclic shearing action decreases both in soil shear strength and in granular cementation force when the sleeve is driven by vibratory hammers, which leads to a partially plugged mode of the soil plug inside the sleeve. Accordingly, the penetration resistance of sleeve driven by vibratory hammers is the smallest compared to those by other installation methods. When driving the sleeve, the annular soil arches forming in the soil plug at sleeve end induce a significant rise in the internal shaft resistance. Moreover, the influence of vibration frequencies, sleeve diameters, and soil layer properties on the soil plug was investigated in detail, and at the same time improved formulas were brought forward to describe the soil plug resistance inside vibratory driven sleeve. PMID:27386238

  8. The Applied Example of GBF Polymer Alloy Thin-walled Tube Cast-in-situ Concrete Hollow Floor%GBF高分子合金薄壁管现浇混凝土空心楼盖应用实例

    Institute of Scientific and Technical Information of China (English)

    安娜

    2014-01-01

    在高层公共建筑中,GBF高分子合金薄壁管现浇混凝土空心楼盖得到了越来越广泛的应用。本文结合广州市某信息中心工程实例,介绍了该项目中现浇混凝土空心楼盖施工的要点、难点,并提出解决方法,确保了工程质量。%In public high-rise buildings, GBF polymer alloy thin-waled tube cast-in-place concrete holow floor has been widely used. In this paper, based on the example of an inf- ormation center project in Guangzhou City, the author intr- oduced the key points, difficulties of the project in the co- nstruction of the cast-in-situ concrete holow floor, put forward solutions to ensure the engineering quality.

  9. Hydration evolution of pre-cast concrete with steam and water curing

    Institute of Scientific and Technical Information of China (English)

    巴明芳; 钱春香

    2013-01-01

    The hydration characteristics of pre-cast concrete considering the effects of effective initial steam-curing and water-curing duration were measured and analyzed with XRD, TG, X-ray CT, SEM-BSE and MIP techniques. The results show that the effective initial steam-curing duration for pre-cast concrete with lower water-binder ratio was 10 14 h at 50 °C and the initial water-curing duration was 7 14 d. And the hydration evolution of cement, fly ash and slag in pre-cast concrete was obtained respectively by combining the hydrochlorides and EDTA selecting dissolution methods, based on which the contents of hydrated and anhydrate in concrete were calculated and the corresponding dynamic capillary porosity was also determined. Moreover, the comparison between calculated results and experimental ones indicates that the proposed evolution models of microscopic characteristics corresponding to hydration kinetics of cemented materials could be adopted to predict the developing trend of capillary porosity and hydration-products content in pre-cast concrete with fly ash and slag under certain curing conditions.

  10. Discussion on the Design of Cast-in-situ Concrete Hollow Floor Structure%现浇混凝土空心楼盖结构设计探讨

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    In recent years, with the construction technology mature of cast-in-place concrete hol ow floor, this technique is widely used. This article explains the current development sit-uation of floor technology, makes an analysis of the force cha-racteristics of floor structure, expounds the calculation method of floor structure and scope, and briefly introduces the design points, structure and construction key of cast-in-situ concrete hol ow floor.%  近年来,随着现浇混凝土空心楼盖技术的成熟,建筑工程广泛地运用了这个技术。本篇文章详细解释了楼盖技术的发展现状,分析了楼盖结构的受力特性,重点阐述了楼盖结构的计算方法及适应范围,并对现浇混凝土空心楼盖结构的设计要点、构造及施工重点等进行简述。

  11. 砖混结构混凝土现浇板收缩裂缝的数值分析%NUMERICAL ANALYSIS ON SHRINKAGE CRACKS OF CONCRETE CAST SLAB IN BRICK AND CONCRETE STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    贾强; 王子卿

    2011-01-01

    middle of the slab. Along the longitudinal direction of the slab, the tension stress caused by concrete shrinkage became bigger from an end room to a central room, and the increasing rates were from 5 percent to 7 percent. The difference of the tension stress between the longitudinal and transverse directions of the slab was small. The maximum tension stress appeared at the boundaries between the wall and the cast slab when there was no thread tube in the middle part of the slab. Because there was stress concentration phenomena due to the existence of a thread tube, the shrinkage cracks appeared at places. The shrinkage stress depended on the lateral rigidity of the walls which was direct proportional to the crossing area of the walls. The lateral rigidity of the walls could be reduced with the increasing of space. Therefore, the level of the shrinkage stress could be reduced by increasing cross-wall space.

  12. Construction standardization management practice of long screw drilling cast in place pile%长螺旋钻孔压灌桩施工标准化管理实践

    Institute of Scientific and Technical Information of China (English)

    冯红民

    2015-01-01

    结合某油库长螺旋钻孔压灌桩施工标准化管理的实例,详细介绍了钢筋笼制作、成孔、灌注混凝土、下插钢筋笼四个流程的施工技术要点,以期为类似工程的施工提供参考依据。%Combined with the examples of a oil storage construction standardization management of long screw drilling cast in place pile,and in-troduce the construction technology of make reinforcing cage,drill hole,castinplace concrete,underthrust reinforcing cage,which has provided some guidance for similar engineering.

  13. Use of SCC in Prefabricated Concrete Elements

    DEFF Research Database (Denmark)

    Thrane, Lars Nyholm; Lauritsen, Ib

    2004-01-01

    This paper presents observations made on the use of self-compacting concrete for pre-cast elements at Byggebjerg Beton A/S during the last 3 years. The elements include L- and sandwich elements and are mainly produced for agriculture purposes. In general, the flow properties and air content are...... concrete to achieve a good surface quality with a limited number of blowholes. For horizontal castings it is important to keep the concrete flowing to avoid casting joints. Blocking is avoided by using the right type of spacers and a maximum size aggregate of 8mm. However, if the concrete has to flow over...

  14. Briefing Construction Technologies and Application of CBM Internal Mold Cast-in-Situ Concrete Hollow Floor%浅谈CBM内模现浇混凝土空心楼盖施工技术及应用

    Institute of Scientific and Technical Information of China (English)

    李新革

    2015-01-01

    文章结合工程实例,介绍CBM内模现浇混凝土空心楼盖的构造、施工方法及应用效果,提出现浇混凝土空心楼盖中内模抗浮装置及其施工方法,可有效解决因内模带动楼板钢筋上浮而影响结构质量安全的难题。%Combining engineering cases, this paper introduces structure, construction method and application results of CBM internal mold cast-in-situ concrete hollow floor, proposes internal mold anti-floating devices in cast-in-situ concrete hollow floor and its construction method that can effectively solve the problem that internal mold drives lfoor bars to rise so as to inlfuence the structure quality.

  15. Discuss the Full Framing Construction of Cast-in-place Box Girder%浅谈现浇箱粱满堂支架搭设施工

    Institute of Scientific and Technical Information of China (English)

    黄亮

    2013-01-01

    在进行桥梁上部结构的箱梁现浇施工时,满堂支架法的应用已经非常普遍。但是在进行满堂支架法施工时,其施工事故发生的频率也比较高。如何有效提高满堂支架法的施工安全,是值得去深入探究的问题。%During conduct the box girder cast-in-place const-ruction of upper structure in bridge, the application of ful fra-ming method has become so common. But when making ful framing construction method, its construction has a high acide-nt frequency. It is worth to delve into the problem of how to i-mprove the method of ful framing construction safety.

  16. 无梁现浇混凝土GBF管空心楼盖施工技术例析%Case study of construction technology of concrete hollow floor without beam and cast in situ

    Institute of Scientific and Technical Information of China (English)

    张俊; 何松泉; 李昌贤

    2009-01-01

    GBF concrete hollow floor without beam is a new type structure with low weight and high rigidity,the architecture function of this floor is good and fit for cast in situ,while its price is low.Keeping the GBF tube from moving or floating and ensuring the concrete quality below the tube are the difficulties of construction for the floor.In the construction of the case given,a special fixing set is designed to ensure the quality of hollow floor,in the mean time,concrete is cast by two steps, by these measures, the quality of GBF concrete hollow floor without beam is ensured.%无梁现浇混凝土GBF管空心楼盖具有自重小、刚度大、建筑使用功能好、施工便捷以及综合造价低等优点,该新型楼盖的施工重点是确保GBF管在混凝土浇筑时不发生移位和上浮,以及防止管底混凝土产生蜂窝孔洞.采用专门设计的"云梯状"定位钢筋和混凝土分步浇筑等措施,成功克服了GBF管空心楼盖的施工难点,保证了整个工程的施工质量.

  17. PZT-Based Detection of Compactness of Concrete in Concrete Filled Steel Tube Using Time Reversal Method

    Directory of Open Access Journals (Sweden)

    Shi Yan

    2014-01-01

    Full Text Available A smart aggregate-based approach is proposed for the concrete compactness detection of concrete filled steel tube (CFST columns. The piezoceramic-based smart aggregates (SAs were embedded in the predetermined locations prior to the casting of concrete columns to establish a wave-based smart sensing system for the concrete compactness detection purpose. To evaluate the efficiency of the developed approach, six specimens of the CFST columns with the rectangular cross-section were produced by placing some artificial defects during casting of concrete for simulating various uncompacted voids such as cavities, cracks, and debond. During the test, the time reversal technology was applied to rebuild the received signals and launch the reversed signals again by SAs, to overcome the issue of the lack of the prototype. Based on the proposed nonprototype, two indices of time reversibility (TR and symmetry (SYM were applied to relatively evaluate the level of concrete compactness in the range of the two SAs. The experimental results show that the developed method can effectively detect the compactness of concrete in CFST columns.

  18. Influence of formwork surface on the orientation of steel fibres within self-compacting concrete and on the mechanical properties of cast structural elements

    DEFF Research Database (Denmark)

    Svec, Oldrich; Zirgulis, Giedrius; Bolander, John E.;

    2014-01-01

    tomography, indicate that fibres tend to orient according to the flow patterns during casting, but such tendencies are suppressed near rough formwork surfaces. Fibre orientation, in turn, affects the mechanical properties of the concrete as demonstrated by the load testing of beams extracted from the cast......The influences of formwork surface on the final orientation of steel fibres immersed in self-compacting concrete and on the resulting mechanical response of the cast structural elements are investigated. Experimental observations of fibre orientation within cast slabs, obtained via computed...... slabs. These processes and results are simulated using a computational fluid dynamics model of the casting process, in tandem with a lattice model of the fracture of the beam specimens. The computational fluid dynamics model determines the coordinates of each fibre within the concrete, which serve...

  19. Research based teaching as a model for developing complex pre-cast concrete structures

    DEFF Research Database (Denmark)

    Egholm Pedersen, Ole

    2012-01-01

    master students assisted in the development and realisation of an amorphous, catenary grid-shell. Development in many areas simultaneously was essential for the success of the case studies, which made them suitable for a research-based teaching setup, where didactic considerations on a general......: viewing the teaching studio as an interdisciplinary laboratory. On a specific level, didactic considerations involved a division of responsibility into smaller areas of investigation, allowing the students to conduct relevant experimentation while negotiating other areas of the research. Also......This paper describes the potentials of utilising research-based teaching as a method for developing advanced concrete structures in an architectural context. A novel technique for casting concrete elements in PETG plastic is described as a body of research that formed the basis of a case in which...

  20. Chloride migration in concrete with superabsorbent polymers

    OpenAIRE

    Hasholt, Marianne Tange; Jensen, Ole Mejlhede

    2015-01-01

    Superabsorbent polymers (SAP) can be used as a means for internal curing of concrete. In the present study, the development of transport properties of concrete with SAP is investigated. The chloride migration coefficient according to NT BUILD 492 is used as a measure of this. Twenty concrete mixtures aretested 7, 14, and 28 days after casting. The development of degree of hydration is followed for 20 corresponding paste mixtures.Both when SAP is added with extra water to compensate the SAP wa...

  1. Application of New Technology that Unlike Hollow Floor of BDF Cast-in-situ Reinforced Concrete%有别于BDF现浇钢筋混凝土空心楼板的新技术的应用

    Institute of Scientific and Technical Information of China (English)

    蒋志坚

    2011-01-01

    The cast-in-situ hollow slab is the high strength composite foam ball which is the each interval along with direction of the force in the middle of casting slab. The beam d structure generally set in the dark plate, and the after floor of pouring concrete becomes a hollow structure. Soft hollow ball have resonance effect compared the BDF hollow thin-walled tube, the chapping by stress concentration generated is less, and other benefits is equivalent to the hollow floor technology of BDF hollow thin-walled tube cast-in-situ reinforced concrete.%现浇空心楼板是在现浇楼板的截面中部沿受力方向设置相互间隔的高强复合泡沫球,结构的梁一般暗设在板内,浇筑混凝土后楼板变成空心结构.柔软中空球较BDF空心薄壁管有共振作用,对应力集中所产生龟裂较少,其他优点等同于BDF空心薄壁管现浇钢筋混凝土空心楼板技术.

  2. Application of Safe to Design of a Super High-riseBuilding Basement of Cast-in-situ Hollow Concrete Floor System%地下室现浇空心楼盖结构SAFE有限元分析

    Institute of Scientific and Technical Information of China (English)

    林锋

    2015-01-01

    The Cast-in-situ hollow concrete floor system has been widely applied in recent years. SAFE is the ultimate tool for concrete floor and founda-tion system design. The application of SAFE in the basement of Cast-in-situ hollow concrete floor system is mainly introduced. Based on the specialty of this project, issues that should be noted and corresponding measures in the design are presented.%近年来现浇空心楼盖的应用越来越广泛。SAFE是设计混凝土楼板和基础的国际通用结构分析软件。该文主要介绍SAFE程序在某超高层项目地下室现浇空心楼盖设计中的应用情况。针对工程的特点,提出了应注意的问题及设计中相应的措施。

  3. The application of orthogonal experimental design in cast asphalt concrete construction mix design%沥青混凝土配合比设计的正交法应用

    Institute of Scientific and Technical Information of China (English)

    慈平

    2012-01-01

    The method of orthogonal design can be used in asphalt concrete mix design. The results show that the orthogonal experimental design can be achieved with the number of nine test groups to i-dentify indicators to meet the design requirements when the cast asphalt concrete mix design is carried out and the significant influence factors and the level of this test can be found by analysis of variance and range analysis%在进行沥青混凝土配合比设计时,可采取正交设计的方法.结果表明,正交法以九个试验组即可找出满足设计要求的参数指标,并通过方差分析和极差分析可以找出显著的影响因素以及验证本次试验的水平.

  4. 现浇混凝土楼板裂缝产生的原因及防治措施%Cast-in-situ concrete floor board cracking causes and preventing measures

    Institute of Scientific and Technical Information of China (English)

    李建庆; 李树国

    2014-01-01

    The thesis introduces several cast-in-situ concrete floor board cracking styles,analyzes cracking causes from various aspects,and dis-cusses the concrete floor board cracks preventing and processing measures by combining with construction norms,operation procedures and con-struction experience,with a view to strengthen the floor utilization functions.%介绍了现浇混凝土楼板裂缝的几种形式,从各个角度对裂缝产生的原因进行了分析,结合施工规范、操作规程和施工经验,对混凝土楼板裂缝的预防及处理措施进行了论述,以增强楼板的使用功能。

  5. DEVELOPMENT OF A CONCRETE MODEL GENERATION METHOD USING CONSEPT OF FORMWORK

    Science.gov (United States)

    Joko, Masanori; Aruga, Takashi; Yabuki, Nobuyoshi

    In civil engineering works, concrete structures such as pier or retaining wall are generally build up with cast-in-place concrete that is made with ready-mixed concrete placed into forms. However, since the three dimensional models are made as a finished product in design stage, the forms are not used as an element for making of three dimensional models. We focused the cast-in-place concrete structures and performed a fundamental study to develop a method for making three dimensional models with forms. Additionally, we showed an example of cast-in-place concrete structure and described the method of making forms, validation of gaps between forms, validation of polyhedron, generation of concrete model, calculation of amounts and approximate estimates of construction cost.

  6. 现浇混凝土空心楼盖在地下工程中应用的适用性问题探讨%Discussion on Applicability of Cast-in-Situ Concrete Hollow Floor in Underground Engineering

    Institute of Scientific and Technical Information of China (English)

    戴建宁

    2015-01-01

    Based on the analysis of characteristic of cast-in-situ concrete hollow floor components,the applicability of this kind of structure forms in underground engineering was discussed. The structure forms of cast-in-situ concrete hollow flat slab floor under large loading were not suitable in the seismic region. And for the civil air-defense engineering under explosive loading,the structure forms should not be adopted because of the existence of brittle failure and weak anti-penetration capability.%通过对现浇混凝土空心楼盖构件特性分析,论述了这种结构形式在地下工程中的适用性。承受大荷载现浇混凝土空心无梁楼盖结构形式在抗震地区不宜采用。对于承受爆炸荷载的人防工程由于会出现脆性破坏的情况和抗侵彻能力弱,不应采用。

  7. 混凝土大跨现浇空心楼盖挠度控制探讨%DEFLECTION CONTROL OF LARGE SPAN CAST-IN SITU HOLLOW CONCRETE FLOOR

    Institute of Scientific and Technical Information of China (English)

    王世平; 张洪学

    2009-01-01

    This article introduced the large span cast-in-situ hollow concrete floor system deflection control and the project application,the union actual project need,proposed exerts the pre-stressed strap beam on the column the method.Carries the examination through the finite element analysis with the piles,the solution great span cast-in-situ hollow concrete floor system deflection control question,its conclusion may supply further to promote time the application refers.%介绍了混凝土大跨现浇空心楼盖的挠度控制与工程应用,结合实际工程需要,提出在柱上板带梁施加预应力的方法.通过有限元分析与堆载检验,解决大跨现浇空心楼盖挠度控制问题,其结论可供进一步推广应用时参考.

  8. On the Cold In-place Recycling of Asphalt Concrete Pavement%浅谈沥青混凝土路面现场冷再生技术

    Institute of Scientific and Technical Information of China (English)

    方建明

    2009-01-01

    In the recovery work of Highway Tongeheng-Zhongyang that was damaged after heavy snow, the technique of cold in-place recycling of asphalt concrete pavement to make the new base was applied. Practice indicates that the quality of the new base meet all technical requirement. The article discusses this technique in terms of censtructinn preparation, construction process and test after coastruetinn.%文章介绍桐城至枞阳段雪灾后恢复项目养护工程中冷再生沥青混凝土基层施工,主要从沥青路面现场冷再生施工准备、施工程序、施工后检测的情况,讨论了沥青路面现场冷再生施工技术,实践证明,其冷再生沥青混凝土基层施工质量达到新建基层的各项技术标准.

  9. Study and installation of concrete shielding in the civil engineering of nuclear construction (1960); Etude et mise en place des betons de protection dans le genie civil des ouvrages nucleaires (1960)

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, F. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    The object of this report is to give technical information about high density concretes which have become very important for radiation biological shielding. The most generally used heavy aggregates (barytes, ilmenite, ferrophosphorus, limonite, magnetite and iron punching) to make these concretes are investigated from the point of view prospecting and physical and chemical characteristics. At first, a general survey of shielding concretes is made involving the study of components, mixing and placing methods, then, a detailed investigation of some high density concretes: barytes concrete, with incorporation of iron punching or iron shot, ferrophosphorus concrete, ilmenite concrete and magnetite concrete, more particularly with regard to grading and mix proportions and testing process. To put this survey in concrete form, two practical designs are described such as they have been carried out at the Saclay Nuclear Station. Specifications are given for diverse concretes and for making the proton-synchrotron 'Saturne' shielding blocks. (author) [French] Ce rapport a pour objet de donner des precisions techniques au sujet des betons a haute densite qui ont pris une grande importance pour la protection biologique contre les rayonnements. Les agregats lourds les plus couramment utilises (barytine, ilmenite, ferrophosphore, limonite, magnetite et riblons) pour la fabrication de ces betons, sont examines du point de vue prospection et caracteristiques physiques et chimiques. On procede d'abord a une etude generale des betons de protection comprenant l'etude des constituants, de la confection et de la mise en place, ensuite, a un examen detaille de quelques betons a haute densite: betons a base de barytine, avec incorporation de riblons ou de grenaille de fonte, betons au ferrophosphore, a base d'ilmenite ou de magnetite, notamment en ce qui concerne la granulometrie, la composition, le dosage et les processus d'essais. Pour concretiser ces

  10. 谈现浇混凝土楼板裂缝的成因及控制措施%Talking on cracking causes and controlling measures of cast-in-situ concrete floor slab cracks

    Institute of Scientific and Technical Information of China (English)

    白洁

    2012-01-01

    To begin with the types and forms of floor slab cracks,the essay analyzes causes of cast-in-situ concrete floor slab cracks,explores the crack controlling measures,and then introduces the crack processing methods,which has significant guiding meaning for improving construction engineering quality.%从楼板裂缝的种类及形式入手,针对现浇混凝土楼板产生的原因进行了分析,探讨了裂缝的控制措施,同时介绍了裂缝的处理方法,对提高建筑工程质量具有重要的指导意义。

  11. Field test study of pile-soil load transfer characteristics of X-shaped cast-in-place pile%现浇X形桩桩-土荷载传递规律现场试验研究

    Institute of Scientific and Technical Information of China (English)

    丁选明; 孔纲强; 刘汉龙; 吕亚茹

    2012-01-01

    A new pile type, X-shaped cast-in-place concrete pile (XCC pile) was developed for coast or river soft soils treatment. XCC piles have many technical and economic advantages, such as large surface area, high shaft friction, conveniently construction, and high economic effects. But there were relative little studies focused on- the pile-soil load transfer characteristics of XCC pile composite foundation. Based on a sewage treatment plant soft ground improvement engineering, field tests for the pile-soil load transfer of XCC pile composite foundation were carried out. The load-settlement, pile-soil load sharing, pile-soil stress ratio, and the distributions of axial force of pile shaft were measured. Then the pile-soil interaction and neutral plane of XCC pile under different conditions were analyzed. In order to do comparative analysis, the static load tests for circular pile which has the same concrete amount with that of XCC pile were carried out. The results show that, the neutral plane of XCC pile in composite foundation is mainly occurred in 0.2 times of pile depth. The maximum value of positive skin friction is about 140 % of those of negative skin friction. The pile-soil stress ratio of XCC pile in composite foundation is increased with the decreasing of pile spacing under the same pile length.%现浇X形混凝土桩(简称X形桩)是为了更好地满足沿海、沿江软土地基处理应用而开发的一种新桩型.该新型桩具有比表面积大、侧向摩阻力高,施工便捷,经济效益高等技术经济优势;但针对其在复合地基中桩-土荷载传递规律特性的研究却相对较少.结合某污水处理厂软基处理工程,开展了X形桩复合地基中桩-土荷载传递规律的现场试验,测得了荷载-沉降关系,桩-土荷载分担比、桩-土应力比,以及桩身轴力等发展情况,分析了不同工况下复合地基中桩-土协调相互作用和中性点位置规律;并将等混凝土用量圆形桩和X形桩

  12. Early-Age Strength of Ultra-High Performance Concrete in Various Curing Conditions

    Directory of Open Access Journals (Sweden)

    Jong-Sup Park

    2015-08-01

    Full Text Available The strength of Ultra-High Performance Concrete (UHPC can be sensitively affected by the curing method used. However, in contrast to the precast plant production of UHPC where a standard high-temperature steam curing is available, an optimum curing condition is rarely realized with cast-in-place UHPC. Therefore, the trend of the compressive strength development of UHPC was experimentally investigated in this study, with a focus on early-age strength by assuming the various curing conditions anticipated on site. Concrete specimens were cured under different conditions with variables including curing temperature, delay time before the initiation of curing, duration of curing, and moisture condition. Several conditions for curing are proposed that are required when the cast-in-place UHPC should gain a specified strength at an early age. It is expected that the practical use of UHPC on construction sites can be expedited through this study.

  13. Interface Microstructures in Concrete

    Directory of Open Access Journals (Sweden)

    Puertas, Francisca

    1991-03-01

    Full Text Available This paper constitutes a compilation as well as an interpretation of the present state of knowledge about the different microstructures developed in the interface areas of concrete, that is, the cement paste-aggregates, the cement paste-reinforcement, the cement paste-fiber, etc. The Chemical reactions taking place in interface areas, the development and morphology of such areas and their strength ^since interfaces are taken as the weakest points of concrete are the aspects dealt with in some detail in this work.

    El presente trabajo constituye un resumen y también una interpretación del estado actual del conocimiento respecto de las diferentes microestructuras que se desarrollan en las zonas interfaciales de los hormigones, es decir: pasta de cemento-áridos, pasta de cemento-armaduras, pasta de cemento-fibras, etc. Las reacciones químicas que tienen lugar en la zona interfacial, el desarrollo y morfología de dicha zona y su resistencia (las interfases se consideran como uno de los puntos débiles del hormigón son los aspectos que con cierto detalle se tratan en el trabajo.

  14. Proposed Model of Predicting the Reduced Yield Axial Load of Reinforced Concrete Columns Due to Casting Deficiency Effect

    Directory of Open Access Journals (Sweden)

    Achillopoulou Dimitra

    2014-12-01

    Full Text Available The study deals with the investigation of the effect of casting deficiencies- both experimentally and analytically on axial yield load or reinforced concrete columns. It includes 6 specimens of square section (150x150x500 mm of 24.37 MPa nominal concrete strength with 4 longitudinal steel bars of 8 mm (500 MPa nominal strength with confinement ratio ωc=0.15. Through casting procedure the necessary provisions defined by International Standards were not applied strictly in order to create construction deficiencies. These deficiencies are quantified geometrically without the use of expensive and expertise non-destructive methods and their effect on the axial load capacity of the concrete columns is calibrated trough a novel and simplified prediction model extracted by an experimental and analytical investigation that included 6 specimens. It is concluded that: a even with suitable repair, load reduction up to 22% is the outcome of the initial construction damage presence, b the lower dispersion is noted for the section damage index proposed, c extended damage alters the failure mode to brittle accompanied with longitudinal bars buckling, d the proposed model presents more than satisfying results to the load capacity prediction of repaired columns.

  15. Influence of water quality on the strength of plain and blended cement concretes in marine environments

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, S.

    2000-03-01

    This paper reports on the results of an experimental investigation carried out to study the effects of the quality of mixing water and initial curing on the strength of concrete exposed to seawater attack. An attempt has been made to consider a set of combinations with mixing water and initial curing conditions such that they reflect the situations of simulated cast-in-situ and precast conditions of concreting in marine environments. The effects of the quality of mixing water and initial curing on the strength of concrete in marine environments were investigated by considering different levels of fly ash replacement and cement type. Concrete specimens made with plain cements, Type 1, 2, and 5, and blended cements made with fly ash were exposed to marine environments for a period of 1 year. The performance of these cements in concrete was evaluated by reduction in compressive strength. Results of this study showed that the use of precasting in place of casting-in-situ mitigates the effect of marine environments on concrete specimens considerably.

  16. Comparison of Design Bearing Capacity and Site Static Load Test of the Cast-in-place Piles in Caohe Aqueduct%漕河渡槽灌注桩承载力与静载试验比较

    Institute of Scientific and Technical Information of China (English)

    杨胜慧

    2013-01-01

    The cast-in-place piles foundation is adopted in the Caohe aqueduct body. There is 0.5 meter of the piles foun-dation entering into the weak weathered rock, the bearing capacity of the piles foundation is calculated according to point bearing pile . The static load test is adopted to check the the bearing capacity of the cast-in-place pile foundation, the test results show that the bearing capacity of pile foundation in Caohe aqueduct meet the design requirements.%漕河渡槽槽身段采用灌注桩基础,桩基进入弱风化岩石0.5m,按纯端承桩计算桩基承载力。采用桩基静载试验检测桩基承载力,试验结果表明,漕河渡槽桩基承载力达到设计要求。

  17. 现浇轻质保温复合墙体施工技术%Construction of Cast-in-place Lightweight Thermal Insulation Composite Wall

    Institute of Scientific and Technical Information of China (English)

    黄旭腾; 杨庆泽

    2014-01-01

    Cast-in-situ lightweight composite insulation wall is erected with light steel keel and ce-ment pressure plate, pouring molding with the new lightweight rigid insulation materials. The new lightweight rigid insulation materials consist of a large amount of tailings, fly ash, boron mud and other in-dustrial waste as the main raw material for recycling. The wall technology with light steel keel in construc-tion industry, horizontal transfer and infiltration of the technical content are researched for determining the construction of cast-in-situ light composite insulation wall, enhancing technology of green environmental protection and energy saving, reducing waste emissions, solving environmental pollution, saving the land resources with good economic benefit and social benefit.%现浇轻质保温复合墙体是利用轻钢龙骨和水泥压力板支模后,现场浇入新型轻质刚性保温材料而制成的一次成型复合墙体,其中新型轻质刚性保温材料是以大量尾矿粉、粉煤灰、硼泥等工业废弃物作为主要原材料,通过可回收再利用,实现变废为宝。通过建筑行业轻钢龙骨墙体施工工艺,横向转移和渗透其技术内容,研究确定现浇轻质保温复合墙体的施工技术,推广应用绿色环保节能技术,减少废弃物排放,解决环境污染问题,节约土地资源,具有良好的经济效益和社会效益。

  18. Constraint-aware interior layout exploration for pre-cast concrete-based buildings

    KAUST Repository

    Liu, Han

    2013-05-03

    Creating desirable layouts of building interiors is a complex task as designers have to manually adhere to various local and global considerations arising from competing practical and design considerations. In this work, we present an interactive design tool to create desirable floorplans by computationally conforming to such design constraints. Specifically, we support three types of constraints: (i) functional constraints such as number of rooms, connectivity among the rooms, target room areas, etc.; (ii) design considerations such as user modifications and preferences, and (iii) fabrication constraints such as cost and convenience of manufacturing. Based on user specifications, our system automatically generates multiple floor layouts with associated 3D geometry that all satisfy the design specifications and constraints, thus exposing only the desirable family of interior layouts to the user. In this work, we focus on pre-cast concrete-based constructions, which lead to interesting discrete and continuous optimization possibilities. We test our framework on a range of complex real-world specifications and demonstrate the control and expressiveness of the exposed design space relieving the users of the task of manually adhering to non-local functional and fabrication constraints. © 2013 Springer-Verlag Berlin Heidelberg.

  19. Non-net casting exterior thermal insulation system on field concrete exterior wall in high storeyed resident building%高层住宅现浇混凝土外墙无网浇合外保温体系

    Institute of Scientific and Technical Information of China (English)

    顾同曾; 夏祖宏; 邸占英

    2001-01-01

    The non - net casting exterior thermal insulation system on field concrete exterior wall in high storeyed resident building is developed firstly at home. This system adopts polystyrene board without steel wire net as thermal insulation board. The cracking resistant layer consists of polymer cement mortar and alkali resistant glass fiber woven scrim, anchored with plastic expanded tube. The tests of bonding power between polystyrene board and concrete, plastic expanded tube pull- out, compressibility, freeze resistance show the system property is reliable and high safe. The thermal measurement test shows the system can meet the requirement of wall body energy - saving 50% stipulated in Beijing "Energy Saving Detailed Regulations", with low construction cost and high work efficiency. The comprehensive construction cost lowers 40%~50% in comparison with back suspending net system.%在国内首次开发了高层住宅现浇混凝土外墙无网浇合外保温体系。该体系采用无钢丝网架的聚苯板为保温板,抗裂层由聚合物水泥砂浆及耐碱玻纤网格布组成,再用塑料胀管锚固。经聚苯板与混凝土粘合力、塑料胀管抗拔力、压缩率及抗冻试验表明该体系性能可靠、安全度高;热工测试表明满足北京市《节能细则》对墙体节能50%的要求;造价低、工效高,综合造价比后挂有网体系降低40%~50%。

  20. 沥青混凝土路面就地热再生施工工艺探讨%Discussion on Construction Process of Hot In -Place Recycling Technology of Asphalt Concrete Pavement

    Institute of Scientific and Technical Information of China (English)

    徐安花; 房建宏

    2015-01-01

    Hot in-place recycling technology of asphalt concrete pavement ,w hich has broad application prospects ,has significant economic and technical advantages in waste utilization ,resource saving ,ecological environmental protecting ,etc .In this paper ,in order to provide guidance to site construction of hot in -place recycling technology ,the essential points and attentions of the construction process of hot in -place recycling technology of asphalt concrete pavement are analyzed from its technological type ,heating method ,scarifying method ,adding mode of additive and construction process .%沥青混凝土路面就地热再生技术在废料利用、资源节约和生态环境保护等方面具有显著的技术和经济优势,具有广阔的应用前景。本文从沥青混凝土路面就地热再生主要工艺类型、加热方式、翻松方式、再生剂添加方式及施工过程等方面分析了沥青路面就地热再生技术施工工艺方面的要点及注意事项,以期为就地热再生技术的现场施工提供指导。

  1. Fracture Mechanisms in Steel Castings

    Directory of Open Access Journals (Sweden)

    Z. Stradomski

    2013-07-01

    Full Text Available The investigations were inspired with the problem of cracking of steel castings during the production process. A single mechanism of decohesion - the intergranular one - occurs in the case of hot cracking, while a variety of structural factors is decisive for hot cracking initiation, depending on chemical composition of the cast steel. The low-carbon and low-alloyed steel castings crack due to the presence of the type II sulphides, the cause of cracking of the high-carbon tool cast steels is the net of secondary cementite and/or ledeburite precipitated along the boundaries of solidified grains. Also the brittle phosphor and carbide eutectics precipitated in the final stage solidification are responsible for cracking of castings made of Hadfield steel. The examination of mechanical properties at 1050°C revealed low or very low strength of high-carbon cast steels.

  2. Segregation in cast products

    Indian Academy of Sciences (India)

    A Ghosh

    2001-02-01

    Microsegregation gets eliminated significantly if subsequent hot working and/or annealing are done on cast products. Macrosegregation however persists, causing problems in quality, and hence, has to be attended to. Microsegregation is a consequence of rejection of solutes by the solid into the interdendritic liquid. Scheil’s equation is mostly employed. However, other equations have been proposed, which take into account diffusion in solid phase and/or incomplete mixing in liquid. Macrosegregation results from movements of microsegregated regions over macroscopic distances due to motion of liquid and free crystals. Motion of impure interdendritic liquid causes regions of positive macrosegregation, whereas purer solid crystals yield negative macrosegregation. Flow of interdendritic liquid is primarily natural convection due to thermal and solutal buoyancy, and partly forced convection due to suction by shrinkage cavity formation etc. The present paper briefly deals with fundamentals of the above and contains some recent studies as well. Experimental investigations in molten alloys do not allow visualization of the complex flow pattern as well as other phenomena, such as dendrite-tip detachment. Experiments with room temperature analogues, and mathematical modelling have supplemented these efforts. However, the complexity of the phenomena demands simplifying assumptions. The agreement with experimental data is mostly qualitative. The paper also briefly discusses centreline macrosegregation during continuous casting of steel, methods to avoid it, and the, importance of early columnar-to-equiaxed transition (CET) as well as the fundamentals of CET.

  3. Glazed Concrete

    DEFF Research Database (Denmark)

    Bache, Anja Margrethe

    2010-01-01

    Why glazed concrete? Concrete hardens and finds its strength at room temperature whereas clay products must first be fired before they achieve this strength. They are stronger and three times as durable as clay products, which is a weighty reason for choosing concrete.5 Another reason, which....... If this succeeds, it will be possible to manufacture thin, large-scale glazed concrete panels comparable in size to concrete sandwich construction and larger which, with or without back-casting, can work as load-bearing construction elements....

  4. Design and application on the gypsum embedded filler cast-in-situ concrete hollow floor%石膏空腔模填充混凝土空心楼盖研制及应用

    Institute of Scientific and Technical Information of China (English)

    肖良锦; 曹磊芳; 高朋朋

    2011-01-01

    A new type of cast-in-situ concrete hollow floor is put forward.The characteristics of this floor are introduced from the aspects of processing, designing, oonstruction, structural, economic, application and so on.The results show that there are many advantages such as economical, practical, easy construction etc about this system.So this environmental protection and energy hollow floor system is worth using wildly.%提出了一种新型现浇混凝土空心楼盖,从加工、研制、施工、结构、经济、运用等方面介绍了这种新型楼盖的特性.研究与运用结果表明,该楼盖体系具有经济、实用、易施工、结构性能好等诸多优点,是值得推广的环保节能型空心楼盖体系.

  5. Setting the scene in Nuuk: Introducing the cast of characters in Greenlandic foreign policy narratives

    DEFF Research Database (Denmark)

    Jacobsen, Marc; Gad, Ulrik Pram

    2016-01-01

    cultural traditions with envisioned future independence. Hence, the chapter introduces the central members of the cast of characters in the most important narratives, which Greenland is telling about its place in the world. The analysis shows how narratives about indigenous identity combines...... international politics and foreign policy as driven by narratively structured discourses constructing nation state identities in relation to Others....... policy strategy; “It is important that the interest in the Arctic and Greenland is converted into concrete opportunities for the Greenlandic people and its development as a nation” (2011:3). This chapter investigates how Greenland’s foreign policy supports the national self-image in combining indigenous...

  6. Water Entrainment in Concrete

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Hansen, Per Freiesleben

    This report gives a survey of different techniques for incorporation of designed, water-filled cavities in concrete: Water entrainment. Also an estimate of the optimum size of the water inclusions is given. Water entrainment can be used to avoid self-desiccation and self-desiccation shrinkage...... during hydration [1,26]. What is needed is some sort of container which retains the shape of the water when mixed into the concrete. The container may function based on several different physical or chemical principles. Cells and gels are examples of containers found in nature. A cell membrane provides...... a boundary to water, whereas a polymer network incorporates water in its intersticious space with its affinity due to interaction energy and polymer entropy. Such containers allow water to be stored as an entity. In relation to concrete the water encapsulation may be accomplished either before or after start...

  7. Lost Foam Casting in China

    Institute of Scientific and Technical Information of China (English)

    YE Sheng-ping; WU Zhi-chao

    2006-01-01

    @@ 1. Lost Foam Casting Committee of Foundry Institution of Chinese Mechanical Engineering Society (FICMES) From the beginning of the 1990s, China entered a research and expansion climax in lost foam casting technology realm after the United States, Germany, and Japan etc.

  8. Reusing recycled aggregates in structural concrete

    Science.gov (United States)

    Kou, Shicong

    results, a number of recommendations were made on how to optimize the use of recycled aggregates for structural concrete production. The results demonstrate that one of the practical ways to utilize a higher percentage of recycled aggregates in concrete is "precasting" with the use of fly ash and an initial steam curing stage immediately after casting.

  9. Place in Transition

    DEFF Research Database (Denmark)

    Mikkelsen, Jacob Bjerre; Lange, Ida Sofie Gøtzsche

    redefinition of oil rigs from an urban design perspective. The paper constitutes a theoretical basis for future design scenarios - exemplified through visionary urban design proposals for a specific site in the city of Esbjerg, Denmark. Relocating rigs to an urban context initiates discussions of conception of...... 'Place' questioning the fixity of 'Place' (Jensen 2010). Scoped through a relational sense of place (Massey 1993) and the potential of exploring new relations between places (Burns & Kahn 2005), the paper challenges the notion of 'Place as God' (Hvattum 2010). These places in transition contest the...

  10. Modification of the cast concrete mixture by air-entraining agents

    Directory of Open Access Journals (Sweden)

    N.I. Vatin

    2015-06-01

    Full Text Available The paper investigates the combined effect of superplasticizer based on the naphthalene lignosulfonate and the air-entraining surfactant agent on the fluidity, connectivity and air entrainment of concrete. The air-entraining surfactant agent contributes significantly into air entrainment and reduces the water gain and the mortar separation. It was found that under the introduction of air-entraining surfactant agents in the concrete mixture which contains the superplasticizer, the concrete mobility decreases even though the air-entraining agent is a plasticizer itself. The introduction of 0.1 % air-entraining agent decreases mobility: slump Abrams – 5–6 %, slump flow – 18–22 %. Besides, the effect of increasing the connectivity of the concrete mix is associated with the air entrainment. Regardless of the air-entraining surfactant agent, the superplasticizer reduces water separation, and does not have an air-entraining impact, and virtually has no effect on the air entrainment caused by the addition of the air-entraining agent. With the increasing quantity of the air-entraining surfactant agent in the concrete mix, regardless of the superplasticizer dosage, the amount of the entrained air increases from 3 to 7 %, and water separation is reduced to almost 0. Thus, the synergy of the superplasticizer and the air-entraining agent was negative, but it is possible to observe a positive effect in respect of the concrete mix connectivity.

  11. 现浇X形群桩竖向抗拔特性及影响因素分析%Vertical Uplift Capacity Characteristics and Influence Factor Analysis of Cast-in-situ X-section Reinforced Concrete Pile Group

    Institute of Scientific and Technical Information of China (English)

    孔纲强; 丁选明; 陈育民; 杨贵

    2012-01-01

    Based on Nanjing Sewage Treatment Plant soft ground improvement engineering, field tests of X-section cast-in-situ reinforced concrete pile (referred to as XCC pile) under vertical uplift bearing capacity were carried out, in which the relation curves of load-displacement were measured. Numerical models for XCC single pile and pile group under uplift load were built by using FLAC3D software. The simulation result was compared with single pile field test result. Comparing analysis with the bearing capacity of circular piles under uplift load was carried out. Then, the mechanical properties of XCC pile group which were influenced by pile length, pile-soil fraction coefficient and pile position were analyzed and discussed. The study results show that the vertical uplift bearing capacity of XCC pile is relatively equals to that of circular pile with the same out-diameters, nearly 17. 4% larger than that of circular pile with the same concrete volumes.%结合南京某污水处理厂软基处理工程,开展了现浇X形钢筋混凝土桩(简称X形桩)单桩竖向抗拔承载力现场试验,测得了荷载-位移关系曲线;基于FLAC3D软件建立了竖向上拔荷载作用下X形单桩、群桩特性分析的数值模型,并与现场单桩抗拔试验结果进行对比分析;比较研究了与等效圆形截面桩抗拔承载力的差异,并分析了基桩长度、桩-土摩擦因数以及基桩位置等因素对X形群桩力学特性的影响规律.研究结果表明:X形桩竖向抗拔承载力与其等外包直径的圆形截面桩承载力相近,较等混凝土用量的圆形截面桩承载力提高了近17.4%.

  12. TEXTILE TECHNOLOGIES IN CONCRETE ENVIRONMENTS."

    OpenAIRE

    Morrow, Ruth; Belford, Patricia

    2007-01-01

    Girli Concrete is a cross disciplinary funded research project based in the University of Ulster involving a textile designer/ researcher, an architect/ academic and a concrete manufacturing firm.Girli Concrete brings together concrete and textile technologies, testing ideas ofconcrete as textile and textile as structure. It challenges the perception of textiles as only the ‘dressing’ to structure and instead integrates textile technologies into the products of building products. Girli Concre...

  13. Niobium in gray cast iron

    International Nuclear Information System (INIS)

    The potential for utilization of niobium in gray cast iron is appraised and reviewed. Experiments described in literature indicate that niobium provides structural refinement of the eutectic cells and also promotes pearlite formation. (Author)

  14. Early Property Development in Concrete

    DEFF Research Database (Denmark)

    Normann, Gitte; Munch-Petersen, Christian

    2014-01-01

    The Freiesleben Maturity function is widely used for planning of execution. We tested if for concrete with and without fly ash. The test showed surprisingly that the maturity function in general is not valid. We found that curing at high temperature gave a significant decrease in strength. Fly ash...... appears to reduce this decrease somewhat. We also examined the resistance against chloride penetration for the different concrete types. The resistance was reduced at high temperatures for concrete without fly ash. For concrete with fly ash, it was the opposite; concrete with fly ash obtained higher...

  15. 三岔双向挤扩灌注桩在桥梁设计中的应用%Application of Cast-in-place Pile with Expanded Branches and Bells by 3-way Extruding Arms in Bridge Design

    Institute of Scientific and Technical Information of China (English)

    张睿

    2016-01-01

    Through the design analysis of a bridge project pile,the cast-in-place piles with expanded branches and bells by 3-way extruding arms in the basic principle and design method are described in this paper and their vertical bearing capacity are calculated.The economic advantage and vertical bear-ing capacity advantage are verified,and the problems of its application in bridge engineering design are presented.%通过对某桥梁项目灌注桩的设计分析,阐述了三岔双向挤扩灌注桩的基本原理和设计方法,分别计算了三岔双向挤扩灌注桩与普通钻孔灌注桩的单桩竖向承载力,验证了三岔双向挤扩灌注桩在经济性及桩基竖向承载力等方面的优势,并提出了该桩基在桥梁工程设计中需要注意的问题。

  16. Cast-in-situ concrete hollow slab floor lightweight composite box in the application in the engineering%现浇混凝土空心板楼盖轻质复合箱体在工程中的应用

    Institute of Scientific and Technical Information of China (English)

    吴文海

    2011-01-01

    This paper describes the cast-in-situ concrete hollow slab floor lightweight composite box in engineering application of construction method,and analysis of the causes of the construction quality and the corresponding quality the quality of prevention and%本文通过工程实例,介绍现浇混凝土空心板楼盖轻质复合箱体在工程应用中的施工方法,及分析施工质量产生的原因及提出相应的质量质量预防和控制措施。

  17. Construction and Preliminary HVS Tests of Pre-Cast Concrete Pavement Slabs

    OpenAIRE

    Kohler, Erwin R.; du Plessis, Louw; Theyse, Hechter

    2008-01-01

    This report presents the details on the construction and preliminary load tests on an experimental pavement comprised of ten pre-cast slabs of the pavement known as the Super-Slab® System, installed at the intersection of I-15 and SR210, in San Bernardino County in southern California. The construction of the test section consisted of: (a) Construction of a cement-treated base (CTB), (b) Preparation of a sand bedding layer, (c) Placement of the pre-cast slabs, (d) Application of grout materi...

  18. Place Branding in Systems of Place

    DEFF Research Database (Denmark)

    Zenker, Sebastian; Andéhn, Mikael

    2015-01-01

    of place is thought to influence the prospects of branding campaigns and introduce and discuss how reassociation can serve as means of mitigation of negative supranational belongingness. In doing so, we discuss also the challenges of interregional branding in this regard, where perceptions of two (or more.......g. the European Union or Africa). Using the example of nation branding for Sudan and Slovenia, one can identify supranational places such as “sub-Saharan Africa” or “Eastern Europe”, carrying their own highly salient and often negative meaning in much of the Western world. We explore how association to a system...

  19. Evaluation of isotropy in wet-mix sprayed concrete

    Directory of Open Access Journals (Sweden)

    Yubero, E.

    2009-07-01

    Full Text Available It is well known that there are differences between the fresh mix concrete and the placed concrete sprayed using dry or wet-mix process. Because of that, the characterization of such material is carried out in cores extracted parallel to the spray direction from sample panels. However, in many applications (e.g. tunnel lining, considerable compressive stresses appear along the transversal direction. In this paper different spayed concretes are evaluated. It was observed that the values of compressive strength and modulus of elasticity were different depending on the direction of measurement. These differences are related to a preferential orientation of the coarse aggregate due to the characteristics of the casting process. Rather than applying classic empirical methods, the concrete mixes used in this study were designed according to a new proportioning method based on the difference between the composition of the fresh mix concrete and the placed concrete.Dadas las diferencias entre el hormigón de partida y el colocado, la evaluación de las propiedades de un hormigón proyectado, por vía húmeda o seca, se realiza mediante la extracción de testigos, evaluándose las propiedades mecánicas o deformacionales de forma uniaxial, según la dirección de la proyección. No obstante, son muchas las aplicaciones, como es el caso del sostenimiento en túneles, en las que esta disposición no representa la forma de trabajo principal del hormigón en la estructura. En el presente artículo se ha verificado que pueden existir diferencias en la resistencia a compresión y módulo de elasticidad del hormigón proyectado por vía húmeda, según la dirección de evaluación. Éstas van ligadas a la orientación que sufre el árido grueso como consecuencia de la puesta en obra del hormigón. Asimismo, el hormigón proyectado del estudio se ha dosificado utilizando como procedimiento de dosificación una propuesta metodológica, basada en las diferencias

  20. Influence of adjuvants on the properties of underwater cast concrete on base of cement (HRS 32.5 N

    Directory of Open Access Journals (Sweden)

    Rouis Mohamed Jamel

    2014-04-01

    *The characterization tests of concrete in the hardened state including destructive and non destructive tests performed on specimens made in concrete (based on portland cement, with varying dosages and adjuvants at different times (28d and 90d.

  1. Non-destructive monitoring of curing process in precast concrete

    International Nuclear Information System (INIS)

    Currently, the use of precast concrete elements has gained importance because it offers many advantages over site-cast concrete. A disadvantage of site-cast concrete is that its properties vary according to the manufacturing method, the environment and even the operator who carried out the mixing, pouring and implementation of the concrete. Precast concrete elements are manufactured in a controlled environment (typically referred to as a precast plant) and this reduces the shrinkage and creep. One of the key properties of precast concrete is the capability to gain compressive strength rapidly under the appropriate conditions. The compressive strength determines if the precast can be stripped from the form or manipulated. This parameter is measured using destructive testing over cylindrical or cubic samples. The quality control of precast is derived from the fracture suffered by these elements, resulting in a 'pass or fail' evaluation. In most cases, the solution to this problem is to allow the material to cure for a few hours until it acquires sufficient strength to handle the precast element. The focus of this paper is the description of the research project 'CUREND'. This project aims to design a non-destructive methodology to monitor the curing process in precast concrete. The monitoring will be performed using wireless sensor networks.

  2. Non-destructive monitoring of curing process in precast concrete

    Science.gov (United States)

    Aparicio, S.; Ranz, J.; Fernández, R.; Albert, V.; Fuente, J. V.; Hernández, M. G.

    2012-12-01

    Currently, the use of precast concrete elements has gained importance because it offers many advantages over site-cast concrete. A disadvantage of site-cast concrete is that its properties vary according to the manufacturing method, the environment and even the operator who carried out the mixing, pouring and implementation of the concrete. Precast concrete elements are manufactured in a controlled environment (typically referred to as a precast plant) and this reduces the shrinkage and creep. One of the key properties of precast concrete is the capability to gain compressive strength rapidly under the appropriate conditions. The compressive strength determines if the precast can be stripped from the form or manipulated. This parameter is measured using destructive testing over cylindrical or cubic samples. The quality control of precast is derived from the fracture suffered by these elements, resulting in a "pass or fail" evaluation. In most cases, the solution to this problem is to allow the material to cure for a few hours until it acquires sufficient strength to handle the precast element. The focus of this paper is the description of the research project "CUREND". This project aims to design a non-destructive methodology to monitor the curing process in precast concrete. The monitoring will be performed using wireless sensor networks.

  3. Experimental Evaluation and Implementation of Post-Tensioning in Concrete Bridge Decks

    OpenAIRE

    Ramirez, Julio A.; Aguilar, Gerardo

    2010-01-01

    A research program was conducted to evaluate the design recommendations for transverse post-tensioning of bridge decks developed in the FHWA/IN/JTRP/2002-26 (SPR-2409) report. The test specimen consisted of a 40x18 ft cast-in-place concrete deck on precast pretensioned girders. Thirty-two tests were carried out by applying different distributions of transverse post-tensioning force, in combination with a changing number of diaphragms, and two conditions of end-restraint at the supports. The t...

  4. Teaching Bodies in Place

    Science.gov (United States)

    Jones, Stephanie; Woglom, James F.

    2013-01-01

    Background/Context: This piece draws on literature in justice-oriented teacher education, feminist pedagogy, and postmodern notions of bodies and place to make sense of data generated from a three-year study of an undergraduate teacher education course. A feminist lens was used to engage a body- and place-focused pedagogy that aimed to engage…

  5. Chlorine signal attenuation in concrete.

    Science.gov (United States)

    Naqvi, A A; Maslehuddin, M; ur-Rehman, Khateeb; Al-Amoudi, O S B

    2015-11-01

    The intensity of prompt gamma-ray was measured at various depths from chlorine-contaminated silica fume (SF) concrete slab concrete specimens using portable neutron generator-based prompt gamma-ray setup. The intensity of 6.11MeV chloride gamma-rays was measured from the chloride contaminated slab at distance of 15.25, 20.25, 25.25, 30.25 and 35.25cm from neutron target in a SF cement concrete slab specimens. Due to attenuation of thermal neutron flux and emitted gamma-ray intensity in SF cement concrete at various depths, the measured intensity of chlorine gamma-rays decreases non-linearly with increasing depth in concrete. A good agreement was noted between the experimental results and the results of Monte Carlo simulation. This study has provided useful experimental data for evaluating the chloride contamination in the SF concrete utilizing gamma-ray attenuation method.

  6. Research progress on squeeze casting in China

    Institute of Scientific and Technical Information of China (English)

    Li Yuanyuan; Zhang Weiwen; Zhao Haidong; You Dongdong; Zhang Datong; Shao Ming; Zhang Wen

    2014-01-01

    Squeeze casting is a technology with short route, high efficiency and precise forming, possessing features of casting and plastic processing. It is widely used to produce high performance metallic structural parts. As energy conservation and environmental protection concerns have risen, lightweight and high performance metal parts are urgently needed, which accelerated the development of squeeze casting technology over the past two decades in China. In this paper, research progress on squeeze casting aloys, typical parts manufacturing and development of squeeze casting equipment in China are introduced. The future trend and development priorities of squeeze casting are discussed.

  7. Flow Induced segregation in full scale castings with SCC

    DEFF Research Database (Denmark)

    Thrane, Lars Nyholm; Stang, Henrik; Geiker, Mette Rica

    2007-01-01

    Though promising, pioneering work has been carried out with rheological characterization and numerical modelling of form filling with SCC, the approach is far from standard in the concrete industry and clearly the approach does not yet hold all the answers to relevant questions. In particular flow...... induced segregation is a major risk during casting and it is not yet clear how this phenomenon should be modelled. In this paper testing and numerical simulations of full-scale wall castings are compared. Two different SCCs and three different filling methods were applied resulting in different flow...... patterns during form filling. Results show that the flow patterns have a major influence on the risk of flow induced segregation and the surface finish of the hardened concrete. A hypothesis for the mechanism of flow induced segregation is put forth....

  8. The Application of the Midas/Civil Software to the Simulation Calculation of Supporting Brackets for Cast-in-Place Beams%Midas/Civil软件在现浇梁支架模拟计算中的应用

    Institute of Scientific and Technical Information of China (English)

    陶友海

    2012-01-01

    The Tangxun Lake Mega Bridge of the newly-built Wuhan-to-Xianning Inter-city Railway, the upper structure of which,in design,is a dual-unit continuous beam,the lower structure of which is made up of five road-spanning piers,is to span the Jiangxia Avenue at a small angle, and in the process of the construction of which the road-spanning portal pier brackets for capping beams and road-spanning supporting brackets for cast-in-place continuous curved beams have to be built. The establish- ment of a space model by means of the Midas/Civil Software and the process of accurately simulating the calculation of the brackets for cast in-place beams under stress, including the setting of the boundary conditions, handling of loads, structural cluster approach and so on, are dealt with in detail in the paper. The calculated results show that the stability of the supporting brackets along the longitudinal direction of the capping beam is poor, in which case they have to be strengthened ~ the shear force at the bottom chord bar of the beam body bracket for the horizontal Bailey Beam is too large,and thus it has to be reinforced. The thinking ways and thinking processes to solve such problems described in the paper may serve as a useful reference for oth- er similar projects.%新建武汉至咸宁城际铁路汤逊湖特大桥小角度跨越江夏大道,上部结构设计为2联连续梁,下部设计为5座跨路门式墩,施工中搭设跨路门式墩盖梁支架和跨路现浇连续弯梁支架。详细介绍了使用Midas/Civ-il软件建立空间模型、准确模拟受力进行现浇支架计算的过程,包括边界条件的设定、荷载的处理和结构分组办法等。计算结果表明:支架门式墩盖梁梁体长度方向稳定性较差,需要加固处理;梁体支架横向贝雷梁下弦杆剪力偏大,改为加强型。文中的考虑解决问题的方法思路和过程可以为类似的工程提供借鉴。

  9. Cementite Solidification in Cast Iron

    Science.gov (United States)

    Coronado, J. J.; Sinatora, A.; Albertin, E.

    2014-06-01

    Two hypereutectic cast irons (5.01 pct Cr and 5.19 pct V) were cast and the polished surfaces of test pieces were deep-etched and analyzed via scanning electron microscopy. The results show that graphite lamellae intersect the cementite and a thin austenite film nucleates and grows on the cementite plates. For both compositions, graphite and cementite can coexist as equilibrium phases, with the former always nucleating and growing first. The eutectic carbides grow from the austenite dendrites in a direction perpendicular to the primary plates.

  10. Radiographic testing in concrete structures

    International Nuclear Information System (INIS)

    The radiographic testing done in concrete structures is used to analyse the homogeneity, position and corrosion of armatures and to detect discontinuity in the concrete such as: gaps, cracks and segregations. This work develops a Image quality Indicator (IQI) with an adequated sensibility to detect discontinuites based on BS4408 norm. (E.G.)

  11. Context in place

    DEFF Research Database (Denmark)

    Nordentoft, Helle Merete; Thomsen, Rie

    The purpose of this paper is to provide a theoretical framework - i.e. a vocabulary - for understanding the importance of integrating context in analyses of guidance practices. The paper delineates a conceptual landscape of context based on social practice and interactional theories on context. We...... studies on interdisciplinary clinical supervision and work place guidance in which there appears to be a mismatch between intended outcomes and actual events. The analyses demonstrate and support that 'the place' seems - to influence partipants' responses in the guidance sessions and, therefore, must be...... specifically argue for a more grounded approach to the conception of context - a topographic approach - in which the physical setting - i.e. 'the place' becomes an inevitable part of analyses of guidance practices in order to understand participants' sense-making processes. In the paper we draw on two case...

  12. Ageing in Communal Place

    DEFF Research Database (Denmark)

    Aarhus, Rikke; Ballegaard, Stinne Aaløkke; Grönvall, Erik;

    2009-01-01

    In this paper we adopt the position that design of social media for the elderly and virtual senior communities may be informed by studying ‘real’ senior communities. Since current research efforts target the role of social media and virtual communities for supporting seniors ageing in place, i...... these findings apply to designers of social media technologies. .......e. in their homes, housing communities seem a natural place to begin this enquiry. We conducted observations and informal interviews in six different senior dwellings. In this paper we present the key findings from these visits related to social interaction and the formation of communities and explicate how...

  13. Ageing in communal place

    DEFF Research Database (Denmark)

    Aarhus, Rikke; Ballegaard, Stinne Aaløkke; Grönvall, Erik;

    2009-01-01

    In this paper we adopt the position that design of social media for the elderly and virtual senior communities may be informed by studying `real´senior communities. Since current research efforts target the role of social media and virtual communities for supporting seniors ageing in place, i...... these findings apply to designers of social media technologies........e. in their homes, housing communities seems a natural place to begin this enquiry. We conducted observations and informal interviews in six different senior dwellings. In this paper we present the key findings from these visits related to social interaction and the formation of communities and explicate how...

  14. Durability of concrete in saline environment

    OpenAIRE

    1996-01-01

    Contents: - Systematic collection of field data for service life prediction of concrete structures. - Moisture in marine concrete structures - Studies in the BMV-project 1992-1996. - Scaling resistence of concrete field exposure tests. - Chloride induced corrosion in marine concrete structures. - Chloride threshold values in reinforced concrete. - A new method for determing chloride thresholds as a function of potential in field exposure tests. - Estimation of chloride ingress into concrete a...

  15. Study of potential advantages of pre-soaking on the properties of pre-cast concrete made with recycled coarse aggregate

    Directory of Open Access Journals (Sweden)

    Sánchez-Roldán, Z.

    2016-03-01

    Full Text Available Recycled aggregate (RA from construction and demolition waste is traditionally used for the manufacture of concrete for different applications. Due primarily to high water content required by RA, the quality of the concrete is determined by the amount of replacement RA. The aim of this study is to determine if RA pre-soaking enhances the properties of pre-cast concrete for street furniture, with low mechanical and structural requirements, in which 100% of the coarse fraction is replaced. The results of physical and mechanical tests performed on concrete specimens in which the RA was pre-soaked using five different methods applied are compared with a reference concrete sample and a concrete sample made with non-pre-soaked RA. The results show that non-pre-soaked RA offers improved physical-mechanical properties for pre-cast concrete, except for the workability; problems arising from poorer workability could be improved with the use of plasticizers, which can be easily included in the production process.El árido reciclado (AR procedente de residuos de construcción y demolición se utiliza tradicionalmente en la elaboración de hormigón para diferentes aplicaciones. Debido principalmente al mayor contenido en agua requerido por el AR, la calidad del hormigón está determinada por la cantidad de AR reemplazado. El objetivo de este estudio es determinar si el AR premojado mejora las propiedades del hormigón prefabricado para mobiliario urbano, con bajas exigencias mecánicas y estructurales, en el que se sustituye el 100% de la fracción gruesa. Los resultados de los ensayos físicos y mecánicos realizados sobre muestras de hormigón en las cuales el AR se ha premojado usando cinco métodos diferentes se han comparado con una muestra de hormigón de referencia y una muestra de hormigón fabricada con AR no premojado. Los resultados muestran que el AR no premojado proporciona propiedades físico-mecánicas mejoradas en el hormigón prefabricado

  16. Shear reinforced beams in autoclaved aerated concrete

    DEFF Research Database (Denmark)

    Cornelius, Thomas

    2010-01-01

    Shear behaviour in concrete materials is very well documented, for normal density concrete materials. In this paper results of various tests on low density concrete materials like aerated autoclaved concrete (in the following denoted aircrete) will be presented and analyzed for different combinat......Shear behaviour in concrete materials is very well documented, for normal density concrete materials. In this paper results of various tests on low density concrete materials like aerated autoclaved concrete (in the following denoted aircrete) will be presented and analyzed for different...

  17. Use Of Crushed Bricks As Coarse Aggregate In Concrete

    Directory of Open Access Journals (Sweden)

    Fadia S. Kalak

    2013-05-01

    Full Text Available The investigation reported in this paper is carried out to study the feasibility of using crushed bricks to substitute the coarse aggregate (gravel in concrete. Two types of concrete mixing are prepared. The first one is a mixture of  1:2:4 without crushed bricks and is used as a reference mixture .The second one is made of different weight of crushed bricks (as a percentage from the weight of the coarse aggregate. A total of 30 numbers of concrete specimens are casted with and without crushed bricks and  tested under compression and split tension as per relevant to British standard specifications.Test results indicated that using crushed bricks reduces the strength of concrete. Also, the percentage of water to cement ratio increases for constant slump when the percentage of crushed bricks increased.

  18. Deterioration of concrete structures in coastal environment due to carbonation.

    Science.gov (United States)

    Balaji, K V G D; Gopalaraju, S S S V; Trilochan, Jena

    2010-07-01

    Failure of existing concrete structures takes place due to lack of durability, and not due to less structural strength. One of the important aspects of durability is carbonation depth. The rate of carbonation in concrete is influenced by both its physical properties and exposure conditions. Rebar corrodes when carbonation reaches to a depth of concrete cover provided. In the present work, various concrete structures with different life periods and exposed to different weather conditions have been considered to study the carbonation effect. It is observed that the effect of carbonation is more in the structures located near to the sea coast and on windward face of the structure. PMID:21391402

  19. In Place of Fishing

    DEFF Research Database (Denmark)

    Ounanian, Kristen

    2016-01-01

    the imposition of transferable catch shares, this research takes a holistic approach to studying coastal communities. This study focuses on instances of transition from a greater presence of the fishing industry to new configurations of fisheries, maritime sectors, and tourism. Situated in places in......, affecting certain segments of the community more severely than others. In addition, the transition to tourism dependence holds a somewhat precarious future for coastal communities in temperate areas. In some cases, heritage and community identity remain strongly connected to the surviving fishing industry...

  20. Prediction of Part Distortion in Die Casting

    Energy Technology Data Exchange (ETDEWEB)

    R. Allen Miller

    2005-03-30

    The die casting process is one of the net shape manufacturing techniques and is widely used to produce high production castings with tight tolerances for many industries. An understanding of the stress distribution and the deformation pattern of parts produced by die casting will result in less deviation from the part design specification, a better die design and eventually more productivity and cost savings. This report presents methods that can be used to simulate the die casting process in order to predict the deformation and stresses in the produced part and assesses the degree to which distortion modeling is practical for die casting at the current time. A coupled thermal-mechanical finite elements model was used to simulate the die casting process. The simulation models the effect of thermal and mechanical interaction between the casting and the die. It also includes the temperature dependant material properties of the casting. Based on a designed experiment, a sensitivity analysis was conducted on the model to investigate the effect of key factors. These factors include the casting material model, material properties and thermal interaction between casting and dies. To verify the casting distortion predictions, it was compared against the measured dimensions of produced parts. The comparison included dimensions along and across the parting plane and the flatness of one surface.

  1. Signs in Place

    DEFF Research Database (Denmark)

    Hamid, Salmiah Binti Abdul; Jensen, Ole B.; Silva, Victor

    Travelling in unfamiliar areas is usually very interesting, however it can also be stressful. People travel or move around in an urban space according to their needs, and the environment can also influence the way people move about from one place to another. If a person gets lost, a map or GPS can...... and geosemiotic studies with regards to the road traffic signs used in urban spaces. The paper ends with a discussion on how people choreograph their movement in their everyday life from two different perspectives: above vs. below....

  2. Signs In Place

    DEFF Research Database (Denmark)

    Hamid, Salmiah Binti Abdul; Jensen, Ole B.; Silva, Victor

    2012-01-01

    Travelling in unfamiliar areas is usually very interesting; however, it can also be stressful. People travel or move around in an urban space according to their needs, and the environment can influence the way people move about from one place to another. If a person gets lost, a map or GPS can...... and geosemiotic studies with regards to the road traffic signs used in urban spaces. The paper ends with a discussion on how people choreograph their movement in their everyday life from two different perspectives: above vs. below...

  3. Evaluation of the Strength Variation of Normal and Lightweight Self-Compacting Concrete in Full Scale Walls

    DEFF Research Database (Denmark)

    Hosseinali, M.; Ranjbar, M. M.; Rezvani, S. M.;

    2011-01-01

    -destructive testing. Self-compacting concrete (SCC) and lightweight self-compacting concrete (LWSCC) with different admixtures were tested and compared with normal concrete (NC). The results were also compared with results for standard cubic samples. The results demonstrate the effect of concrete type on the in situ......The strength of cast concrete along the height and length of large structural members might vary due to inadequate compaction, segregation, bleeding, head pressure, and material type. The distribution of strength within a series of full scale reinforced concrete walls was examined using non...

  4. Where is 'place' in Aging in place?

    DEFF Research Database (Denmark)

    Blaakilde, Anne Leonora

    2015-01-01

    . This article builds on a qualitative study among Danish retirement migrants regarding their experiences with the need for care or support while living abroad. Denmark is a welfare state with a long history of public nursing homes and in-home care for frail elderly persons. This system of governance...... in-home help. It is argued that we should consider public solutions to the problems faced by frail Danish citizens in transnational settings, enhancing their opportunities to live abroad....

  5. Craft in Unexpected Places

    OpenAIRE

    Barber, Claire; Macbeth, Penny

    2015-01-01

    Within the shifting territories of craft practice, the handmade has become a relational form of contemporary activity that transforms our understanding of place through a hands-on minds-on process of collective making. The conceptual significance of craft is activated through a chance encounter with the hand-made in daily life The point of departure for this paper was a conference Outside: Activating Cloth to Enhance the Way We Live held in the winter of 2012 at the University of Hudders...

  6. Discussion on the Formation of Cast-in-situ Concrete Floor Cracks and Its Pre-control and Treatment%浅谈现浇砼结构楼板裂缝的形成、预控及治理

    Institute of Scientific and Technical Information of China (English)

    邱海博

    2012-01-01

    近年来,由于砼材料的广泛使用,其裂缝引发的安全、渗漏、索赔等问题成为公众投诉的焦点,尤其是高层建筑钢筋砼楼板的裂缝.为明晰此类问题产生的成因,使得从事房屋建设的管理、施工人员能充分了解砼楼板裂缝形成的原因,并能结合每个工程的现场实际情况,在施工过程中制定专项裂缝预控措施,减少裂缝的产生.%In recent years, due to the widespread use of concrete materials, problems caused by the cracks of, such as safety, leakage, claim, etc become the focus of public complaints, especially cracks of reinforced concrete floor of high-rise building. In order to clear the causes of such problems, managers and construction personnel should fully understand the causes the formation of crack of concrete floor, and combines the actual situation of each project, to establish special pre-control measures for crack, reduce the produce of cracks in the construction process.

  7. Strangers in Familiar Places

    DEFF Research Database (Denmark)

    Muhr, Sara Louise

    2012-01-01

    Employees working across multiple cultures are exposed to a vast number of different norms and values, and consequentially work is often a struggle to retain a coherent sense of self. However, when international workers travel, they also encounter more bland spaces where familiarity and similarity...... are important. These spaces appear culturally generic to the Western traveler, but are highly Westernized to bring comfort to Western employees traveling in foreign cultures. This paper argues that these spaces are important in cross-cultural identity work in the sense that international workers – professional...... strangers – need these places to belong and relate to familiarity and to regain a sense of identity. Drawing on an illustrative empirical vignette of an international consultant, I demonstrate how culturally generic spaces can be used in identity work of an international relations consultant....

  8. 现浇X形桩桩承式加筋路堤三维有限元分析%Three-dimensional finite element analysis of geogrid-reinforced embankment supported by X-section cast-in-place piles

    Institute of Scientific and Technical Information of China (English)

    陈力恺; 孔纲强; 刘汉龙; 金辉

    2013-01-01

    Geogrid-reinforced and pile-supported expressway embankment has been widely applied to soft ground improvement;but its bearing and deformation mechanism has not been deeply understood. Combining with the Fourth Yangtze River Bridge’s north-line soft ground reinforced project in Nanjing, the numerical method is used to analyze the variations of settlement and stress of pile and soil, pile axial force and excess pore water stress. The results show that road embankment load is mainly borne by piles as a result of the soil arching effect. The soil pressures of pile and soil increase with the development of embankment load firstly;and then the pressure of pile continue to increase while the pressure of soil decreases in the consolidation process of soft soil. The pile axial force increases quickly during the process of filling. Negative skin friction develops along most part of X-section cast-in-place pile shaft;and the neutral point ascends firstly;with the consolidation of soil, the depth of the neutral point becomes deeper;then the neutral point position is unaltered at the end of soil consolidation.%桩承式加筋路堤在高速公路软基处理中得到了广泛应用,但目前对其承载变形机制还缺乏深刻认识。结合南京长江第四大桥北接线段软基加固工程,基于数值方法对现浇 X 形桩桩承式加筋路堤中桩土沉降、桩土应力、桩身轴力及超静孔隙水压力的发展变化规律进行了分析。研究结果表明,受土拱效应影响,路堤填筑荷载主要由桩体承担,桩及桩间土土压力在路堤填筑过程中均逐渐增大,在软基固结过程中,桩顶土压力继续增大而桩间土土压力逐渐减小,最终趋于各自的稳定值;路堤填筑过程中桩身轴力增长较快,现浇X形桩桩身上部较大部分区段存在负摩阻力,桩身中性点位置经历了先逐渐上移、而后向下移动,最终趋于稳定的过程。

  9. 控制钢筋混凝土现浇构件裂缝的施工措施%Construction Measures to Control Cracks of Steel Reinforced Concrete Cast-in-site Member

    Institute of Scientific and Technical Information of China (English)

    徐黛义

    2009-01-01

    There are cracks often to appear in the steel reinforced concrete east-in-site members under the engineering. The article focuses discussion on some detail measures to take in the construction to make the cracks be controlled within the permitted range of the maximum crack width.%在工程中钢筋混凝土现浇构件时常出现裂缝.该文重点论述了在施工中采取一些具体措施,使出现的裂缝控制在最大裂缝宽度允许范围内.

  10. Caste and wealth inequality in India

    OpenAIRE

    Zacharias, Ajit; Vakulabharanam, Vamsi

    2009-01-01

    In this paper, we conduct the novel exercise of analyzing the relationship between overall wealth inequality and caste divisions in India using nationally representative surveys on household wealth conducted during 1991–92 and 2002–03. According to our findings, the groups in India that are generally considered disadvantaged (known as Scheduled Castes or Scheduled Tribes) have, as one would expect, substantially lower wealth than the "forward" caste groups, while the Other Backward Classes an...

  11. Microdefects in cast multicrystalline silicon

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, E.; Klinger, D.; Bergmann, S. [Inst. of Crystal Growth Berlin (Germany)

    1995-08-01

    The microdefect etching behavior of cast multicrystalline BAYSIX and SILSO samples is mainly the same as that of EFG silicon, in spite of the very different growth parameters applied to these two techniques and the different carbon contents of the investigated materials. Intentional decorating of mc silicon with copper, iron and gold did not influence the results of etching and with help of infrared transmission microscopy no metal precipitates at the assumed microdefects could be established. There are many open questions concerning the origin of the assumed, not yet doubtless proved microdefects.

  12. Study and installation of concrete shielding in the civil engineering of nuclear construction (1960)

    International Nuclear Information System (INIS)

    The object of this report is to give technical information about high density concretes which have become very important for radiation biological shielding. The most generally used heavy aggregates (barytes, ilmenite, ferrophosphorus, limonite, magnetite and iron punching) to make these concretes are investigated from the point of view prospecting and physical and chemical characteristics. At first, a general survey of shielding concretes is made involving the study of components, mixing and placing methods, then, a detailed investigation of some high density concretes: barytes concrete, with incorporation of iron punching or iron shot, ferrophosphorus concrete, ilmenite concrete and magnetite concrete, more particularly with regard to grading and mix proportions and testing process. To put this survey in concrete form, two practical designs are described such as they have been carried out at the Saclay Nuclear Station. Specifications are given for diverse concretes and for making the proton-synchrotron 'Saturne' shielding blocks. (author)

  13. The pre- stress concrete structure, Found to-be More Effective Then THE Reinforced concrete structure & System developed for mechanism OF, Anchoring devices in pre and post Tensioned concrete structural elements

    Directory of Open Access Journals (Sweden)

    Pradeep Nath Mathur

    2015-04-01

    Full Text Available The pre-stressing concrete Used for casting of section is quite different from reinforced cements concrete (RCC. in concrete Technology. The pre- stressing system used is of two kind, pre- tensioning & posttensioning methods. The prestressing by pre &post tensioning device mechanism, developed for Anchoring system in concrete structural element is adopted for structures. In modern type of Pre stressing electricity with Low voltage and high current is used in anchoring for a concrete member & sulpher Coating as applied on steel bars working, as duct material before the casting of concrete member. While supplying electricity in the structure sulpher get melted up because heat generated in the steel structure & allow them for pre stressing. No provision of any duct is required .The High strength steel alloy structure could be anchored by tightening nuts at both the ends. The Pre-stressing in concrete structure is found more effective then RCC technology. To-day prestressing is preferred for large structures like bridges etc. ,it is required to adopted for all small concrete structure sections also. It is to-days demand to replace RCC completely by Pre-stress concrete, because of RCC have large section with less strength as compare to pre-stress concrete. In RCC System it is rein-forced first and then loaded after casting, when ever in the Pre stressing system, where reinforcement which may called ‘tendons’ are as one kind used for stressing in the concrete itself . They are stressed first then casted & force is applied. It is required that, effective & less cost (Economic anchoring devices must be available for the prestressing techniques; It is because of its initial investment is high and less pre-stress work is restricted also, must be possible to make adoption easily. It is found possible to make concrete having light weight & high strength in all structures. High strength alloy steel & Rich strength concrete may be used along with large

  14. Development and application of titanium alloy casting technology in China

    Institute of Scientific and Technical Information of China (English)

    NAN Hai; XIE Cheng-mu; ZHAO Jia-qi

    2005-01-01

    The development and research of titanium cast alloy and its casting technology, especially its application inaeronautical industry in China are presented. The technology of molding, melting and casting of titanium alloy, casting quality control are introduced. The existing problems and development trend in titanium alloy casting technology are also discussed.

  15. Modelling reinforcement corrosion in concrete

    DEFF Research Database (Denmark)

    Michel, Alexander; Geiker, Mette Rica; Stang, Henrik;

    2012-01-01

    A physio-chemical model for the simulation of reinforcement corrosion in concrete struc-tures was developed. The model allows for simulation of initiation and subsequent propaga-tion of reinforcement corrosion. Corrosion is assumed to be initiated once a defined critical chloride threshold...... is reached causing the formation of anodic and cathodic regions along the reinforcement. Critical chloride thresholds, randomly distributed along the reinforcement sur-face, link the initiation and propagation phase of reinforcement corrosion. To demonstrate the potential use of the developed model......, a numerical example is pre-sented, that illustrates the formation of corrosion cells as well as propagation of corrosion in a reinforced concrete structure....

  16. Yield Improvement in Steel Casting (Yield II)

    Energy Technology Data Exchange (ETDEWEB)

    Richard A. Hardin; Christoph Beckermann; Tim Hays

    2002-02-18

    This report presents work conducted on the following main projects tasks undertaken in the Yield Improvement in Steel Casting research program: Improvement of Conventional Feeding and Risering Methods, Use of Unconventional Yield Improvement Techniques, and Case Studies in Yield Improvement. Casting trials were conducted and then simulated using the precise casting conditions as recorded by the participating SFSA foundries. These results present a statistically meaningful set of experimental data on soundness versus feeding length. Comparisons between these casting trials and casting trials performed more than forty years ago by Pellini and the SFSA are quite good and appear reasonable. Comparisons between the current SFSA feeding rules and feeding rules based on the minimum Niyama criterion reveal that the Niyama-based rules are generally less conservative. The niyama-based rules also agree better with both the trials presented here, and the casting trails performed by Pellini an d the SFSA years ago. Furthermore, the use of the Niyama criterion to predict centerline shrinkage for horizontally fed plate sections has a theoretical basis according to the casting literature reviewed here. These results strongly support the use of improved feeding rules for horizontal plate sections based on the Niyama criterion, which can be tailored to the casting conditions for a given alloy and to a desired level of soundness. The reliability and repeatability of ASTM shrinkage x-ray ratings was investigated in a statistical study performed on 128 x-rays, each of which were rated seven different times. A manual ''Feeding and Risering Guidelines for Steel Castings' is given in this final report. Results of casting trials performed to test unconventional techniques for improving casting yield are presented. These use a stacked arrangement of castings and riser pressurization to increase the casting yield. Riser pressurization was demonstrated to feed a casting up to

  17. Properties of salt-saturated concrete and grout after six years in situ at the Waste Isolation Pilot Plant

    International Nuclear Information System (INIS)

    Samples of concrete and grout were recovered from short boreholes in the repository floor at the Waste Isolation Pilot Plant more than six years after the concrete and grout were placed. Plugs from the Plug Test Matrix of the Plugging and Sealing Program of Sandia National Laboratories were overcored to include a shell of host rock. The cores were analyzed at the Waterways Experiment Station to assess their condition after six years of service, having potentially been exposed to those aspects of their service environment (salt, brine, fracturing, anhydrite, etc.) that could cause deterioration. Measured values of compressive strength and pulse velocity of both the grout and the concrete equaled or exceeded values from tests performed on laboratory-tested samples of the same mixtures at ages of one month to one year after casting. The phase assemblages had changed very little. Materials performed as intended and showed virtually no chemical or physical evidence of deterioration. The lowest values for strength and pulse velocity were measured for samples taken from the Disturbed Rock Zone, indicating the influence of cracking in this zone on the properties of enclosed seal materials. There was evidence of movement of brine in the system. Crystalline phases containing magnesium, potassium, sulfate, and other ions had been deposited on free surfaces in fractures and pilot holes. There was a reaction rim in the anhydrite immediately surrounding each recovered borehole plug, suggesting interaction between grout or concrete and host rock. However, the chemical changes apparent in this reaction rim were not reflected in the chemical composition of the adjacent concrete or grout. The grout and concrete studied here showed no signs of the deterioration found to have occurred in some parts of the concrete liner of the Waste Isolation Pilot Plant waste handling shaft

  18. Influence of Technological Parameters of Furane Mixtures on Shrinkage Creation in Ductile Cast Iron Castings

    Directory of Open Access Journals (Sweden)

    Vasková I.

    2014-10-01

    Full Text Available Ductile cast iron (GS has noticed great development in last decades and its boom has no analogue in history humankind. Ductile iron has broaden the use of castings from cast iron into areas, which where exclusively domains for steel castings. Mainly by castings, which weight is very high, is the propensity to shrinkage creation even higher. Shrinkage creation influences mainly material, construction of casting, gating system and mould. Therefore, the main realized experiment was to ascertain the influence of technological parameters of furane mixture on shrinkage creation in castings from ductile iron. Together was poured 12 testing items in 3 moulds forto determine and compare the impact of various technological parameters forms the propensity for shrinkage in the casting of LGG.

  19. Detection of Cast Shadows in Surveillance Applications

    DEFF Research Database (Denmark)

    Erbou, Søren G.; Sørensen, Helge Bjarne Dissing; Stage, Bjarne

    2005-01-01

    Cast shadows from moving objects reduce the general ability of robust classification and tracking of these objects, in outdoor surveillance applications. A method for segmentation of cast shadows is proposed, combining statistical features with a new similarity feature, derived from a physics...

  20. The temperature gradient on section of casting in process of primary crystallization of chromium cast iron

    Directory of Open Access Journals (Sweden)

    A. Studnicki

    2008-08-01

    Full Text Available The methodology of defining in article was introduced the temperature gradient in process of primary crystallization during cooling the casting from chromium cast iron on basis of measurements of thermal field in test DTA-K3. Insert also the preliminary results of investigations of influence temperature gradient on structure of studied wear resistance chromium cast iron.

  1. Self-Compacting Concrete in Precast Elements Industry

    OpenAIRE

    Corneliu Bob; Cătălin Badea; Sorin Dan; András Leidal

    2005-01-01

    In this paper the authors present information about the Self-Compacting Concrete and experimental results regarding the use of them into precast element industry. This type of concrete does not require vibration for placing and compaction; it is able to flow under its own weight, completely filling formwork and achieving full compaction, even in the presence of congested reinforcement. The experimental programme has take into account two prestressed beams which were prefabricated and tested o...

  2. Self-Compacting Concrete in Precast Elements Industry

    Directory of Open Access Journals (Sweden)

    Corneliu Bob

    2005-01-01

    Full Text Available In this paper the authors present information about the Self-Compacting Concrete and experimental results regarding the use of them into precast element industry. This type of concrete does not require vibration for placing and compaction; it is able to flow under its own weight, completely filling formwork and achieving full compaction, even in the presence of congested reinforcement. The experimental programme has take into account two prestressed beams which were prefabricated and tested on a special stands. The beams of Self-Compacting Concrete with the length of 24 m were prepared at „Beton-Star” Kft, Kecsekenet, Hungary, and used at the CASCO, Satu-Mare.

  3. Energy use in selected metal casting facilities - 2003

    Energy Technology Data Exchange (ETDEWEB)

    Eppich, Robert E. [Eppich Technologies, Syracuse, IN (United States)

    2004-05-01

    This report represents an energy benchmark for various metal casting processes. It describes process flows and energy use by fuel type and processes for selected casting operations. It also provides recommendations for improving energy efficiency in casting.

  4. EXPERIMENTAL STUDY ON HIGH STRENGTH SELF COMPACTING CONCRETE INCORPARETED WITH CARBON FIBRE

    OpenAIRE

    S. Shanmugapriya*, M. Gopinath /Ap, R. Ram Kumar, T. Divya

    2016-01-01

    The Self-Compacting Concrete[1] is a concrete which flows and settles due to its own weight without segregation and bleeding .Self-Compacting Concrete is cast so that no additional inner or outer vibration is necessary for the compaction. It flows like “honey” and has a very smooth surface level[2] after placing with regard to its composition, self-compacting concrete consist of the same components as conventionally vibrated concrete, which are cement, aggregate and water, with th...

  5. Chloride migration in concrete with superabsorbent polymers

    DEFF Research Database (Denmark)

    Hasholt, Marianne Tange; Jensen, Ole Mejlhede

    2015-01-01

    Superabsorbent polymers (SAP) can be used as a means for internal curing of concrete. In the present study, the development of transport properties of concrete with SAP is investigated. The chloride migration coefficient according to NT BUILD 492 is used as a measure of this. Twenty concrete...

  6. UNDERSTANDING OF PLAIN CONCRETE DEVELOPMENT IN TWO AIRPORT PROJECTS%从两座机场工程对清水混凝土发展的认识

    Institute of Scientific and Technical Information of China (English)

    杨应辉

    2011-01-01

    Terminal buildings in both Beijing Capital International Airport and Kunming New Airport adopt plain concrete to realize architectural decoration effect in large area at ceiling, column and wall, etc. When fair-faced concrete technique becomes more and more completed and normative, the durability of fair-faced concrete and the expression force of fair-faced art are still two study issues. Furthermore, research and development of substitute product of cast-in-place concrete, industrialized and professional production of precast slab, imitation fair-faced concrete slab and their products are the development trend of fair-faced concrete in the future.%北京首都机场航站楼和昆明新机场航站楼都在天花、柱、墙等部位大面积应用清水混凝土,来做建筑装饰效果.随着清水混凝土技术的日臻完善和规范,清水混凝土的耐久性和清水艺术的表现力是待研究的课题,此外,研发现浇混凝土的替代产品和发展预制、仿清水混凝土以及工厂化专业化生产,也是未来清水混凝土的发展趋势.

  7. Construction Technology of Cast-in-place Pile of Excavation Support under Complicated Geological Conditions%复杂地质条件下基坑支护灌注桩施工技术

    Institute of Scientific and Technical Information of China (English)

    许厚材

    2012-01-01

      There were various obstacles distributed in the miscellaneous fill in the site of Beijing Spring Garden project, such as old pipes, old foundation concrete, concrete blocks, the soil nails and steel strands of old foundation pit support, and there were also some pipelines near the piles need to be protected, the construction was very difficult.According to the engineering conditions,artificial hole-digging, drilling with long spiral drilling machine and post-insert reinforced cage were adopted in this project.The practice shows that these technologies can not only effectively deal with the shallow under-ground obstacles and protect the underground pipelines, but also has many advantages of simple and safe construction, high quality reliability and short construction period.The environment problems of slurry pollution and slurry treatment are com-pletely solved with obvious social and economic efficiency.The paper introduced these technologies about the construction process and operation points.%  北京政泉花园工程地质条件复杂,填土层中分布有各种旧管线、旧混凝土基础、混凝土块以及基坑支护留在土层中的土钉和钢绞线等地下障碍物,灌注桩附近有需要进行保护的管线,施工难度大。结合工程实际,采用人工挖孔、长螺旋钻孔后插钢筋笼施工技术。实践表明,该施工工艺能够有效处理浅层地下障碍物和保护地下管线,同时具有施工简单、安全、质量可靠性高,缩短工期等优点,并从根本上排除了泥浆污染和泥浆处理等环保问题,具有明显的经济效益与社会效益。介绍了该施工技术的施工工艺流程、操作要点。

  8. 十字形沉管灌注桩的成桩工艺技术%Pile-formed technology for cross tube-sinking cast-in-place pile

    Institute of Scientific and Technical Information of China (English)

    邹正盛; 孔清华; 莫云波; 孔红斌

    2012-01-01

    The change of pile cross section can increase the lateral area of pile, and pile bearing capacity can be improved. Based on this, the piles with abnormal section were developed. At present, a variety of special-shaped section piles on which research or application is more, such as X and Y pile, are formed by the casing with uniform section and tube-sinking method in China. Because the deformation resistance capability of these casings is weak, application of these casings on construction of long piles or super-long piles is limited. The casing for the cross shaped pile is the circular steel casing with bottom wings, and has strong resistance to deformation. So, it can be used in construction of big piles, long piles or super-long piles, concrete or reinforced concrete piles, soil-squeezing piles and soil-borrowing piles, which can be used for foundation treatment, and also for construction of the foundation piles. When the special soil-borrowing devices are used for non soil-squeezing piles, quick construction, high efficient pile-forming and low cost can be able to realize.%改变桩截面形状,增加桩周面积,可提高桩承载力,因此导致了异形截面桩的诞生.目前我国研究较多的多种异形截面桩如X桩、Y桩等,均是采用全长等截面的异形截面模管沉管成桩.由于这些异形截面模管抗变形能力相对较弱,在应用到长桩或超长桩的施工上可能会受到一定的限制.十字形桩成桩模管为底部加翼的圆形截面钢模管,抗变形能力强,能成大桩长桩或超长桩、混凝土素桩或钢筋混凝土桩、挤土桩或非挤土桩,既可用于地基处理,也可作为基桩施工.非挤土桩成桩时,采用专用管内取土装置,施工快捷,成桩效率高,成本低.

  9. Characterization of Technetium Speciation in Cast Stone

    Energy Technology Data Exchange (ETDEWEB)

    Um, Wooyong; Jung, Hun Bok; Wang, Guohui; Westsik, Joseph H.; Peterson, Reid A.

    2013-11-11

    This report describes the results from laboratory tests performed at Pacific Northwest National Laboratory (PNNL) for the U.S. Department of Energy (DOE) EM-31 Support Program (EMSP) subtask, “Production and Long-Term Performance of Low Temperature Waste Forms” to provide additional information on technetium (Tc) speciation characterization in the Cast Stone waste form. To support the use of Cast Stone as an alternative to vitrification for solidifying low-activity waste (LAW) and as the current baseline waste form for secondary waste streams at the Hanford Site, additional understanding of Tc speciation in Cast Stone is needed to predict the long-term Tc leachability from Cast Stone and to meet the regulatory disposal-facility performance requirements for the Integrated Disposal Facility (IDF). Characterizations of the Tc speciation within the Cast Stone after leaching under various conditions provide insights into how the Tc is retained and released. The data generated by the laboratory tests described in this report provide both empirical and more scientific information to increase our understanding of Tc speciation in Cast Stone and its release mechanism under relevant leaching processes for the purpose of filling data gaps and to support the long-term risk and performance assessments of Cast Stone in the IDF at the Hanford Site.

  10. Monitoring corrosion in reinforced concrete structures

    Science.gov (United States)

    Kung, Peter; Comanici, Maria I.

    2014-06-01

    Many defects can cause deterioration and cracks in concrete; these are results of poor concrete mix, poor workmanship, inadequate design, shrinkage, chemical and environmental attack, physical or mechanical damage, and corrosion of reinforcing steel (RS). We want to develop a suite of sensors and systems that can detect that corrosion is taking place in RS and inform owners how serious the problem is. By understanding the stages of the corrosion process, we can develop special a sensor that detects each transition. First, moisture ingress can be monitored by a fiber optics humidity sensor, then ingress of Chloride, which acts as a catalyst and accelerates the corrosion process by converting iron into ferrous compounds. We need a fiber optics sensor which can quantify Chloride ingress over time. Converting ferric to ferrous causes large volume expansion and cracks. Such pressure build-up can be detected by a fiber optic pressure sensor. Finally, cracks emit acoustic waves, which can be detected by a high frequency sensor made with phase-shifted gratings. This paper will discuss the progress in our development of these special sensors and also our plan for a field test by the end of 2014. We recommend that we deploy these sensors by visually inspecting the affected area and by identifying locations of corrosion; then, work with the designers to identify spots that would compromise the integrity of the structure; finally, drill a small hole in the concrete and insert these sensors. Interrogation can be done at fixed intervals with a portable unit.

  11. 岭澳核电站叠置现浇钢筋混凝土循环水管沟施工技术%Construction Technology of Circulating Water Pipe Ditch with Cast-in-situ Reinforced Concrete in Ling' ao Nuclear Power Plant

    Institute of Scientific and Technical Information of China (English)

    吴荣; 程惠敏

    2011-01-01

    岭澳核电站二期现浇钢筋混凝土循环水管沟采用双洞上下叠置的结构设计形式,施工难度较大.首先介绍了垂直施工缝和水平施工缝的设置及处理.本工程水管沟内表面模板采用所需半径的特优质刨光模板,外表面使用钢木组合大模板,重点介绍了进水管沟以及排水管沟模板的制作安装工艺.同时指出混凝土浇筑过程中需要采取必要的测温及养护措施,以有效控制温度裂缝的产生.该工程施工质量和防水性能满足设计要求.%The circulating water pipe ditch with cast-in-situ reinforced concrete in Ling' ao Nuclear Power Plant applies the structural type of overlaying, and its construction technology is difficult. The layout and treatment for vertical and horizontal construction joints are introduced firstly. For this engineering, high quality polishing formwork with necessary radius is used for inner formwork, and combination of steel and wood formwork is used for outer ones. The fabrication and installation technology of formwork for inlet and outlet pipe ditch are introduced in detail. It is pointed out that necessary temperature measuring and maintenance methods should be adopted during concrete pouring to control temperature cracks effectively.This engineering' s construction quality and waterproof performance can meet design requirement.

  12. Release of U(VI) from spent biosorbent immobilized in cement concrete blocks

    Energy Technology Data Exchange (ETDEWEB)

    Venkobachar, C.; Iyengar, L.; Mishra, U.K.; Chauhan, M.S. [Indian Inst. of Tech., Kanpur (India)

    1995-12-01

    This paper deals with cementation as the method for the disposal of spent biosorbent, Ganoderma lucidum (a wood rotting macrofungi) after it is used for the removal of Uranium. Results on the uranium release during the curing of cement-concrete (CC) blocks indicated that placing the spent sorbent at the center of the blocks during their casting yields better immobilization of uranium as compared to the homogeneous mixing of the spent sorbent with the cement. Short term leach tests indicated that the uranium release was negligible in simulated seawater, 1.8% in 0.2 N sodium carbonate and 6.0% in 0.2 N HCl. The latter two leachates were used to represent the extreme environmental conditions. It was observed that the presence of the spent biosorbent up to 5% by weight did not affect the compressive strength of CC blocks. Thus cementation technique is suitable for the immobilization of uranium loaded biosorbent for its ultimate disposal.

  13. Cracks in high-manganese cast steel

    Directory of Open Access Journals (Sweden)

    A. Chojecki

    2009-10-01

    Full Text Available The reasons which account for the formation of in service cracks in castings made from Hadfield steel were discussed. To explain the source of existence of the nuclei of brittle fractures, the properties of cast steel were examined within the range of solidification temperatures, remembering that feeding of this material is specially difficult, causing microporosity in hot spots. This creates conditions promoting the formation of microcracks which tend to propagate during service conditions involving high dynamic stresses, and explains why the cracks are mainly characterized by a brittle nature. The reason for crack formation in service are micro-porosities formed during casting solidification.

  14. The quality of the joint between alloy steel and unalloyed cast steel in bimetallic layered castings

    Directory of Open Access Journals (Sweden)

    T. Wróbel

    2012-01-01

    Full Text Available In paper is presented technology of bimetallic layered castings based on founding method of layer coating directly in cast process so-called method of mould cavity preparation. Prepared castings consist two fundamental parts i.e. bearing part and working part (layer. The bearing part of bimetallic layered casting is typical foundry material i.e. ferritic-pearlitic unalloyed cast steel, whereas working part (layer is plate of austenitic alloy steel sort X2CrNi 18-9. The ratio of thickness between bearing and working part is 8:1. The aim of paper was assessed the quality of the joint between bearing and working part in dependence of pouring temperature and carbon concentration in cast steel. The quality of the joint in bimetallic layered castings was evaluated on the basis of ultrasonic non-destructive testing, structure and microhardness researches.

  15. Radionuclide Retention in Concrete Wasteforms

    Energy Technology Data Exchange (ETDEWEB)

    Bovaird, Chase C.; Jansik, Danielle P.; Wellman, Dawn M.; Wood, Marcus I.

    2011-09-30

    Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e., sorption or precipitation); the mechanism of contaminant release; the significance of contaminant release pathways; how wasteform performance is affected by the full range of environmental conditions within the disposal facility; the process of wasteform aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of wasteform aging on chemical, physical, and radiological properties; and the associated impact on contaminant release. This knowledge will enable accurate prediction of radionuclide fate when the wasteforms come in contact with groundwater. The information present in the report provides data that (1) measures the effect of concrete wasteform properties likely to influence radionuclide migration; and (2) quantifies the rate of carbonation of concrete materials in a simulated vadose zone repository.

  16. Welding Tubes In Place

    Science.gov (United States)

    Meredith, R.

    1984-01-01

    Special welding equipment joins metal tubes that carry pressurized cyrogenic fluids. Equipment small enough to be used in confined spaces in which such tubes often mounted. Welded joints lighter in weight and more leak-proof than joints made with mechanical fittings.

  17. Cholesterol in unusual places

    Energy Technology Data Exchange (ETDEWEB)

    Kucerka, N; Nieh, M P; Marquardt, D; Harroun, T A; Wassail, S R; Katsaras, J, E-mail: John.Katsaras@nrc.gc.ca, E-mail: Norbert.Kucerka@nrc.gc.ca

    2010-11-01

    Cholesterol is an essential component of mammalian cells, and is required for building and maintaining cell membranes, regulating their fluidity, and possibly acting as an antioxidant. Cholesterol has also been implicated in cell signaling processes, where it has been suggested that it triggers the formation of lipid rafts in the plasma membrane. Aside from cholesterol's physiological roles, what is also becoming clear is its poor affinity for lipids with unsaturated fatty acids as opposed to saturated lipids, such as sphingomyelin with which it forms rafts. We previously reported the location of cholesterol in membranes with varying degrees of acyl chain unsaturation as determined by neutron diffraction studies (Harroun et al 2006 Biochemistry 45, 1227; Harroun et al 2008 Biochemistry 47, 7090). In bilayers composed of phosphatidylcholine (PC) molecules with a saturated acyl chain at the sn-1 position or a monounsaturated acyl chain at both sn-1 and sn-2 positions, cholesterol was found in its much-accepted 'upright' position. However, in dipolyunsaturated 1,2-diarachidonyl phosphatidylcholine (20:4-20:4PC) membranes the molecule was found sequestered in the center of the bilayers. In further experiments, mixing l-palmitoyl-2-oleoyl phosphatidylcholine (16:0-18:1 PC) with 20:4-20:4PC resulted in cholesterol reverting to its upright orientation at approximately 40 mol% 16:0-18:1 PC. Interestingly, the same effect was achieved with only 5 mol% 1,2-dimyristoyl phosphatidylchoile (14:0-14:0PC).

  18. Fatigue Strain and Damage Analysis of Concrete in Reinforced Concrete Beams under Constant Amplitude Fatigue Loading

    OpenAIRE

    Fangping Liu; Jianting Zhou

    2016-01-01

    Concrete fatigue strain evolution plays a very important role in the evaluation of the material properties of concrete. To study fatigue strain and fatigue damage of concrete in reinforced concrete beams under constant amplitude bending fatigue loading, constant amplitude bending fatigue experiments with reinforced concrete beams with rectangular sections were first carried out in the laboratory. Then, by analyzing the shortcomings and limitations of existing fatigue strain evolution equation...

  19. Study of risk of developing a delayed ettringite formation and its consequences in concrete of nuclear structures

    International Nuclear Information System (INIS)

    Delayed ettringite formation (DEF) in concrete structures is a pathology that can develop when special conditions on the concrete composition, the thermal conditions at the young age and the environment are met. This phenomenon provokes swelling of the material and cracking in the structure. It affects two types of concrete: the concrete heat-treated and the concrete cast in place in massive parts. Although many studies were done before in order to better understand this pathology, the DEF is still not well known. This is due to its complex mechanism, the influential parameters and its consequences on microscopic and structural scales. For that purpose, the thesis work was designed in order to better understand this pathology. Experimental studies were done to evaluate the impact of certain factors during the reaction, by focusing on nuclear application. An important part of this study was dedicated to assess the risk of DEF development in a nuclear power plant, and to understand how this pathology affects the mechanical characteristics and transfer properties of the concrete. Then, we have studied the impact of the hygrometry on the development of DEF. This has lead to identify a relation between environmental humidity and swelling. We have also examined the role of alkali leaching. A follow up study of the transfer properties was also done and was confronted to the observed swelling. Finally, we were interested in the characterization of the aggregates effect on the kinetics and the amplitude of DEF swelling. So, we have examined the parameters related to the size and the volume fraction of granular inclusions. Furthermore, an application of a mesoscopic numerical modeling of swelling is proposed. (author)

  20. Low Background Micromegas in CAST

    Science.gov (United States)

    Garza, J. G.; Aune, S.; Aznar, F.; Calvet, D.; Castel, J. F.; Christensen, F. E.; Dafni, T.; Davenport, M.; Decker, T.; Ferrer-Ribas, E.; Galán, J.; García, J. A.; Giomataris, I.; Hill, R. M.; Iguaz, F. J.; Irastorza, I. G.; Jakobsen, A. C.; Jourde, D.; Mirallas, H.; Ortega, I.; Papaevangelou, T.; Pivovaroff, M. J.; Ruz, J.; Tomás, A.; Vafeiadis, T.; Vogel, J. K.

    2015-11-01

    Solar axions could be converted into x-rays inside the strong magnetic field of an axion helioscope, triggering the detection of this elusive particle. Low background x-ray detectors are an essential component for the sensitivity of these searches. We report on the latest developments of the Micromegas detectors for the CERN Axion Solar Telescope (CAST), including technological pathfinder activities for the future International Axion Observatory (IAXO). The use of low background techniques and the application of discrimination algorithms based on the high granularity of the readout have led to background levels below 10-6 counts/keV/cm2/s, more than a factor 100 lower than the first generation of Micromegas detectors. The best levels achieved at the Canfranc Underground Laboratory (LSC) are as low as 10-7 counts/keV/cm2/s, showing good prospects for the application of this technology in IAXO. The current background model, based on underground and surface measurements, is presented, as well as the strategies to further reduce the background level. Finally, we will describe the R&D paths to achieve sub-keV energy thresholds, which could broaden the physics case of axion helioscopes.

  1. Low Background Micromegas in CAST

    CERN Document Server

    Garza, J G; Aznar, F.; Calvet, D.; Castel, J.F.; Christensen, F.E.; Dafni, T.; Davenport, M.; Decker, T.; Ferrer-Ribas, E.; Galán, J.; García, J.A.; Giomataris, I.; Hill, R.M.; Iguaz, F.J.; Irastorza, I.G.; Jakobsen, A.C.; Jourde, D.; Mirallas, H.; Ortega, I.; Papaevangelou, T.; Pivovaroff, M.J.; Ruz, J.; Tomás, A.; Vafeiadis, T.; Vogel, J.K.

    2015-01-01

    Solar axions could be converted into x-rays inside the strong magnetic field of an axion helioscope, triggering the detection of this elusive particle. Low background x-ray detectors are an essential component for the sensitivity of these searches. We report on the latest developments of the Micromegas detectors for the CERN Axion Solar Telescope (CAST), including technological pathfinder activities for the future International Axion Observatory (IAXO). The use of low background techniques and the application of discrimination algorithms based on the high granularity of the readout have led to background levels below 10$^{-6}$ counts/keV/cm$^2$/s, more than a factor 100 lower than the first generation of Micromegas detectors. The best levels achieved at the Canfranc Underground Laboratory (LSC) are as low as 10$^{-7}$ counts/keV/cm$^2$/s, showing good prospects for the application of this technology in IAXO. The current background model, based on underground and surface measurements, is presented, as well as ...

  2. Running in place

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, R.; Mohsberg, J. (Richard Hunt Associates, Annapolis, MD (United States))

    1993-04-01

    Various resource agencies are diluting FERC's authority to carry out its mandated duties. Greater assertiveness is needed to regain control of the hydropower licensing process. Allowing resource agencies this control has not resulted in a workable process or the timely processing of applications. Several examples illustrate the resulting problems.

  3. Modelling of Level Fluctuation in Continuous Casting

    Institute of Scientific and Technical Information of China (English)

    Xiao LIU; Huanxin ZHANG; Rongjun XU; Yongquan LI; Houfa SHEN; Baicheng LIU

    2003-01-01

    The free surface profile and fluid flow in the mold of continuous casting have been calculated by the VOF method couplingthe SIMPLER algorithm. The SIMPLER-VOF model developed is validated by solving a classical experiment, broken damproblem. The calculat

  4. Control of Early Age Concrete. Phase 3: Creep in Concrete

    DEFF Research Database (Denmark)

    Hauggaard-Nielsen, Anders Boe; Damkilde, Lars; Hansen, Per Freiesleben;

    1997-01-01

    The mechanical properties of the "Road Directorate Concrete" at early ages are studied. Creep in tension at 24 and 72 maturity hours are measured on dogbone shaped specimens. The development of tensile modulus of elasticity and strength are measured with a method developed here. The results...... are compared to compression values and splitting strengths. It is found that the properties of creep in tension are similar to the properties in compression. Further the influence form temperature on creep is found to be significant....

  5. Rare Earth Additions in Continuously Cast Steel

    Science.gov (United States)

    Wilson, William G.; Heaslip, L. J.; Sommerville, I. D.

    1985-09-01

    Rare earth (lanthanide metals) addiiions to continuously cast steel are particularly advantageous because of their ability to refine as-cast structures, reduce segregation and increase hot ductility at temperatures just below that of solidification. The complete shape control of sulfides in steels containing Rare Earth Metals (REM), whether continuously cast or ingot cast, is primarily responsible for improvements in ductility related mechanical properties, weldability, fatigue resistance and resistance to hydrogen damage. Complete sulfide shape control can be obtained with REM additions at sulfur levels as high as.020%. The greatest improvements, however, are obtained with REM additions to low sulfur steels. However, to achieve full operational advantages afforded by REM, nozzle blockage problems must be circumvented. Water model studies indicate a possible solution.

  6. 3-D Temperature and Stress Simulations of Hardening Concrete

    DEFF Research Database (Denmark)

    Jensen, Poul; Buhr, Birit; Thorborg, Jesper;

    2003-01-01

    When concrete is cast, heat develops. When the concrete cools down there is a risk that thermal gradients induce cracks in the structure. In the Middle East this is especially important as extensive heat builds up due to the high ambient temperatures. Possible formed cracks will have a detrimental...... effect on the overall durability of the structure, especially when placed in or close to a marine environment, and especially if placed in a hot and aggressive environment. In order to minimize the risk of inducing thermal cracks, temperature and stress requirements during the hardening period must...... for the thermo-mechanical conditions during hydration of early age concrete. Material properties as a function of maturity and environmental conditions form the basis of the model. This paper presents temperature and stress calculation results using MAGMAconcrete, and proposed hardening precautions for two...

  7. Compressive Strength of Concrete Using Recycled Concrete Aggregate as Complete Replacement of Natural Aggregate

    OpenAIRE

    Osei, Daniel Yaw

    2013-01-01

    This paper presents a report of an experimental investigation on the effect of complete replacement of natural aggregate by recycled concrete aggregate in the production of concrete on the compressive strength of concrete. Two sets of concrete mixtures of ratios 1:3:6, 1:2:4, 1:11/2:3, 1:1:2 by mass were cast using natural aggregates and recycled aggregates concrete respectively. The 28-day compressive strengths of 1:3:6, 1:2:4, 1:11/2:3, 1:1:2 concrete using recycled concrete aggregates were...

  8. Modelling Tension Stiffening in Reinforced Concrete Structures

    DEFF Research Database (Denmark)

    Christiansen, Morten Bo; Nielsen, Mogens Peter

    1997-01-01

    with deformations in reinforced concrete disks subjected to pure shear.A physical model for the shear stress-shear strain behaviour of disks, including tension stiffening, is proposed.In the disk model it is assumed that the tensile principal stress in the concrete decreases linearly from the initiation of cracking......Part I of the present thesis deals with crack formation in reinforced concrete and the phenomenon of tension stiffening in concrete tension rods reinforced with deformed bars.Two physical models are presented for uniaxial tension, and they are modified for application on beams subjected to pure...... flexure.In the first model, the yield zone model, it is assumed that the mean crack distance is a descending function of the reinforcement stress in a crack. Furthermore it is assumed that in certain zones between the cracks the concrete is carrying its full effective tensile strength, i.e. the concrete...

  9. Durability of concrete materials in high-magnesium brine

    International Nuclear Information System (INIS)

    Cement pastes and mortars representing 11 combinations of candidate concrete materials were cast in the laboratory and monitored for susceptibility to chemical deterioration in high-magnesium brine. Mixtures were selected to include materials included in the current leading candidate concrete for seals at the Waste Isolation Pilot Plant (WIPP). Some materials were included in the experimental matrix to answer questions that had arisen during study of the concrete used for construction of the liner of the WIPP waste-handling shaft. Mixture combinations compared Class C and Class F fly ashes, presence or absence of an expansive component, and presence or absence of salt as a mixture component. Experimental conditions exposed the pastes and mortars to extreme conditions, those being very high levels of Mg ion and an effectively unlimited supply of brine. All pastes and mortars showed deterioration with brine exposure. In general, mortars deteriorated more extensively than the corresponding pastes. Two-inch cube specimens of mortar were not uniformly deteriorated, but showed obvious zoning even after a year in the brine, with a relatively unreacted zone remaining at the center of each cube. Loss of calcium from the calcium hydroxide of paste/aggregate interfaces caused measurable strength loss in the reacted zone comprising the outer portion of every mortar specimen. The current candidate mass concrete for WIPP seals includes salt as an initial component, and has a relatively closed initial microstructure. Both of these features contribute to its suitability for use in large placements within the Salado Formation

  10. Structure and mechanical properties of vermicular cast iron in cylinder head casting

    OpenAIRE

    Guzik, E.; S. Dzik

    2009-01-01

    The paper discusses the problem of grain density and ferrite content in microstructure of vermicular graphite iron cast in bars of different section diameters and cylinder head casting. The experimental results regarding the section effect demonstrate that the nodule count, grain density and ferrite content are all function of the cast bar diameter in this particular case ranging from 0.6 to 8.0 cm and microstructure and mechanical properties in the cylinder head. The nodule count (or grain d...

  11. Utilization of Electronic Waste Plastic in Concrete

    OpenAIRE

    Vivek S. Damal; Saurabh S. Londhe

    2015-01-01

    In India, bitumen pavements are commonly used for highways. Due to the increasing traffic intensity, distress such as rutting and cracking of pavements are very common in Indian roads. Under varying seasonal temperature, flexible pavements tend to become soft in summer and brittle in winter. Investigations revealed that properties of concrete can be better than bitumen roads. But now a day‟s concrete roads are used commonly because concrete roads have more life span than the bi...

  12. The change of temperature gradient in solidification of hypereutectic chromium cast iron casting

    OpenAIRE

    A. Studnicki

    2010-01-01

    In article the analysis of temperature gradient of solidification in section of hypereutectic chromium cast iron model casting was introduced. On this example was presented the method (DTGA – derivative and thermal gradient analysis), which was worked out in Department of Foundry Silesian University of Technology enabling the record of indispensable data to execution of analysis the temperature gradient and its derivative after time on section of model casting. It multichanneled apparatus to ...

  13. The change of temperature gradient in solidification of hypereutectic chromium cast iron casting

    Directory of Open Access Journals (Sweden)

    A. Studnicki

    2010-01-01

    Full Text Available In article the analysis of temperature gradient of solidification in section of hypereutectic chromium cast iron model casting was introduced. On this example was presented the method (DTGA – derivative and thermal gradient analysis, which was worked out in Department of Foundry Silesian University of Technology enabling the record of indispensable data to execution of analysis the temperature gradient and its derivative after time on section of model casting. It multichanneled apparatus to registration of data was used Crystaldigraph - PC.

  14. Progress of Carbonation in Chloride Contaminated Concretes

    OpenAIRE

    Wang, Yaocheng; Basheer, P.A.M.; Nanukuttan, S; Bai, Y.

    2016-01-01

    Concretes used in marine environment are generally under the cyclic effect of CO2 and chloride ions (Cl-). To date, the influence of carbonation on ingress of chloride ions in concretes has been widely studied; in comparison, study on the influence of Cl- on the progress of carbonation is limited. During the study, concretes were exposed to independent and combined mechanisms of carbonation and chloride ingress regimes. Profiles of apparent pH and chloride concentration were used to indicate ...

  15. Innovations in nuclear concrete constructions

    International Nuclear Information System (INIS)

    The technical requirements and scope of concrete work on nuclear projects present significant engineering and construction challenges. These demands represent the extremes in many areas of construction operations. In meeting these challenges, engineering and construction forces have developed several innovations which can be beneficially applied to other types of construction. Innovative approaches in the general categories of engineering scope, construction input to engineering, work planning, special methods and techniques, and satisfaction of quality assurance requirements are given in this paper. The transfer of this technology to other segments of the construction industry will improve overall performance by avoiding the problem areas encountered on nuclear projects

  16. An Experimental and Numerical Study on Embedded Rebar Diameter in Concrete Using Ground Penetrating Radar

    Directory of Open Access Journals (Sweden)

    Md Istiaque Hasan

    2016-01-01

    Full Text Available High frequency ground penetrating radar (GPR has been widely used to detect and locate rebars in concrete. In this paper, a method of estimating the diameter of steel rebars in concrete with GPR is investigated. The relationship between the maximum normalized positive GPR amplitude from embedded rebars and the rebar diameter was established. Concrete samples with rebars of different diameters were cast and the maximum normalized amplitudes were recorded using a 2.6 GHz GPR antenna. Numerical models using GPRMAX software were developed and verified with the experimental data. The numerical models were then used to investigate the effect of dielectric constant of concrete and concrete cover on the maximum normalized amplitude. The results showed that there is an approximate linear relationship between the rebar diameter and the maximum GPR normalized amplitude. The developed models can be conveniently used to estimate the embedded rebar diameters in existing concrete with GPR scanning; if the concrete is homogeneous, the cover depth is known and the concrete dielectric constant is also known. The models will be highly beneficial in forensic investigations of existing concrete structures with unknown rebar sizes and locations.

  17. Privileged Girls: The Place of Femininity and Femininity in Place

    Science.gov (United States)

    Fahey, Johannah

    2014-01-01

    Constructions of femininity and attendant notions of feminism are being produced in different ways in different places around the world. This is a complicated global process that cannot be reduced to analyses that take place in nation states. This paper seeks to respond to and enhance Angela McRobbie's compelling argument about understandings…

  18. Upscaling the Use of Mixed Recycled Aggregates in Non-Structural Low Cement Concrete

    Directory of Open Access Journals (Sweden)

    Antonio López-Uceda

    2016-02-01

    Full Text Available This research aims to produce non-structural concrete with mixed recycled aggregates (MRA in upscaled applications with low-cement content. Four slabs were executed with concrete made with different ratios of coarse MRA (0%, 20%, 40% and 100%, using the mix design, the mixing procedures and the facilities from a nearby concrete production plant. The analysis of the long-term compressive and splitting tensile strengths in concrete cores, extracted from the slabs, allowed the highlighting of the long-term high strength development potential of MRA incorporation. The study of cast specimens produced in situ under the same conditions as the slabs showed, firstly, that the use of MRA has a great influence on the properties related to durability, secondly, that the loss of compressive strength for total MRA incorporation relative to control concrete increases proportionally with the class strength, and, thirdly, that the mechanical properties (including Schmidt hammer results from the concrete slabs showed no significant differences relative to the control concrete for coarse aggregates replacements up to 40%. Therefore, this upscaled experimental study supports the application of concrete with 100% coarse MRA incorporation and low cement content in non-structural civil works such as bike lanes, gutters, ground slabs, leveling surfaces, and subgrades for foundations. To the best of the authors’ knowledge, there have not been any upscaled applications of concrete with MRA and low cement content.

  19. Ductility in lightweight concrete with fiber

    OpenAIRE

    Ahmadyar, Milad

    2011-01-01

    This master thesis presents the influence of different fiber in high-performance lightweight concrete and the ductility capacity of reinforced lightweight concrete beam. Twelve beams with length of 2.2m and reinforcement ratio 0.24 have been tested under 4 point bending, three of them were made by normal density aggregates as references beams. The target concrete compressive strength for all beams were 50MPa. Three different types of fibers such as steel fiber, Polypropylene ma...

  20. Integration and road tests of a self-sensing CNT concrete pavement system for traffic detection

    International Nuclear Information System (INIS)

    In this paper, a self-sensing carbon nanotube (CNT) concrete pavement system for traffic detection is proposed and tested in a roadway. Pre-cast and cast-in-place self-sensing CNT concrete sensors were simultaneously integrated into a controlled pavement test section at the Minnesota Road Research Facility (MnROAD), USA. Road tests of the system were conducted by using an MnROAD five-axle semi-trailer tractor truck and a van, respectively, both in the winter and summer. Test results show that the proposed self-sensing pavement system can accurately detect the passing of different vehicles under different vehicular speeds and test environments. These findings indicate that the developed self-sensing CNT concrete pavement system can achieve real-time vehicle flow detection with a high detection rate and a low false-alarm rate. (paper)

  1. Integration and road tests of a self-sensing CNT concrete pavement system for traffic detection

    Science.gov (United States)

    Han, Baoguo; Zhang, Kun; Burnham, Tom; Kwon, Eil; Yu, Xun

    2013-01-01

    In this paper, a self-sensing carbon nanotube (CNT) concrete pavement system for traffic detection is proposed and tested in a roadway. Pre-cast and cast-in-place self-sensing CNT concrete sensors were simultaneously integrated into a controlled pavement test section at the Minnesota Road Research Facility (MnROAD), USA. Road tests of the system were conducted by using an MnROAD five-axle semi-trailer tractor truck and a van, respectively, both in the winter and summer. Test results show that the proposed self-sensing pavement system can accurately detect the passing of different vehicles under different vehicular speeds and test environments. These findings indicate that the developed self-sensing CNT concrete pavement system can achieve real-time vehicle flow detection with a high detection rate and a low false-alarm rate.

  2. Radiation damage in reactor cavity concrete

    International Nuclear Information System (INIS)

    License renewal up to 60 years and the possibility of subsequent license renewal to 80 years has established a renewed focus on long-term aging of nuclear generating stations materials, and recently, on concrete (large irreplaceable sections of most nuclear generating stations include concrete). The Electric Power Research Institute (EPRI) and Oak Ridge National Laboratory (ORNL) have established a research plan to investigate the aging and degradation processes associated with concrete used in NPPs. This paper outlines the research program including: 1) defining the upper bound of the neutron and gamma dose levels expected in the biological shield concrete for extended operation (80 years of operation and beyond), 2) determining the effects of neutron and gamma irradiation as well as extended time at temperature on concrete, 3) evaluating opportunities to irradiate prototypical concrete under accelerated neutron and gamma dose levels to establish a conservative bound and share data obtained from different flux, temperature, and fluence levels, 4) evaluating opportunities to harvest and test irradiated concrete from international NPPs, 5) developing cooperative test programs to improve confidence in the results from the various concretes and research reactors, 6) furthering the understanding of the effects of radiation on concrete and 7) establishing an international collaborative research and information exchange effort to leverage capabilities and knowledge

  3. Strategies for Aging in Place

    Directory of Open Access Journals (Sweden)

    Suzanne Dupuis-Blanchard

    2015-01-01

    Full Text Available For healthy and independent older adults, aging in place can be seen as identical to any other adult living at home. Little is known about how frail seniors, particularly those who speak a minority language, manage the challenges of aging in place. The present qualitative descriptive study explores the strategies that Canadian French-speaking seniors have put in place to counter their loss of independence and promote their ability to stay in their home. Semistructured individual interviews were conducted with 39 older adults and transcribed, followed by content analysis to identify common themes related to study objectives. Six themes emerged in response to strategies described for aging in place. Findings reveal the limited extent to which language issues were perceived as a barrier by participants. In conclusion, the results of this study provide us with fruitful insights to guide community nursing practice, future research, and public policy.

  4. Concrete Flow in Diaphragm Wall Panels: A Full-Scale In-Situ Test

    NARCIS (Netherlands)

    Van Dalen, J.H.; Bosch, J.W.; Broere, W.

    2015-01-01

    Flow processes, taking place during the concreting of diaphragm wall panels (D-wall panels), are of great importance for the quality of the wall. During this phase, the bentonite, present in the excavated trench, should be completely replaced by concrete in a controlled way. In literature several ca

  5. Radionuclide Retention in Concrete Wasteforms

    Energy Technology Data Exchange (ETDEWEB)

    Wellman, Dawn M.; Jansik, Danielle P.; Golovich, Elizabeth C.; Cordova, Elsa A.

    2012-09-24

    Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e., sorption or precipitation); the mechanism of contaminant release; the significance of contaminant release pathways; how wasteform performance is affected by the full range of environmental conditions within the disposal facility; the process of wasteform aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of wasteform aging on chemical, physical, and radiological properties; and the associated impact on contaminant release. This knowledge will enable accurate prediction of radionuclide fate when the wasteforms come in contact with groundwater. Data collected throughout the course of this work will be used to quantify the efficacy of concrete wasteforms, similar to those used in the disposal of LLW and MLLW, for the immobilization of key radionuclides (i.e., uranium, technetium, and iodine). Data collected will also be used to quantify the physical and chemical properties of the concrete affecting radionuclide retention.

  6. Evaluation of porosity in Al alloy die castings

    Directory of Open Access Journals (Sweden)

    M. Říhová

    2012-01-01

    Full Text Available Mechanical properties of an Al-alloy die casting depend significantly on its structural properties. Porosity in Al-alloy castings is one of the most frequent causes of waste castings. Gas pores are responsible for impaired mechanical-technological properties of cast materials. On the basis of a complex evaluation of experiments conducted on AlSi9Cu3 alloy samples taken from the upper engine block which was die- cast with and without local squeeze casting it can be said that castings manufactured without squeeze casting exhibit maximum porosity in the longitudinal section. The area without local squeeze casting exhibits a certain reduction in mechanical properties and porosity increased to as much as 5%. However, this still meets the norms set by SKODA AUTO a.s.

  7. Damage Detection in Laboratory Concrete Beams

    DEFF Research Database (Denmark)

    Brincker, Rune; Andersen, P.; Kirkegaard, Poul Henning;

    The aim of the investigation reported in this paper is to clarify to what extent damages in reinforced concrete can be detected by estimating changes in the vibrational properties. A series of damages were introduced by applying static load cycles of increasing magnitude to two concrete beams...

  8. Computational Modelling of Particle Packing in Concrete

    NARCIS (Netherlands)

    He, H.

    2010-01-01

    Physical particle packing is becoming a hot topic in concrete technology as more and more types of granular materials are used in concrete either for ecological or for engineering purposes. Although various analytical methods have been developed for optimum mixture design, comprehensive information

  9. Maintenance system improvement in cast iron foundry

    Directory of Open Access Journals (Sweden)

    S. Kukla

    2011-07-01

    Full Text Available The work presents the issue of technical equipment management in an iron foundry basing on the assumptions of the TPM system (Total Productive Maintenance. Exploitation analysis of automatic casting lines has been carried out and their work’s influence on the whole production system’s functioning has been researched. Within maintenance system improvement, implementation of autonomic service and planned lines’ review have been proposed in order to minimize the time of breakdown stoppages. The SMED method was used to optimize changeover time, and the OEE (Overall Equipment Effectiveness was applied to evaluate the level of resources usage before and after implementing changes. Further, the influence of the maintenance strategy of casting devices’ efficiency on own costs of casting manufac- ture was estimated.

  10. Mechanical and thermal properties of prepacked aggregate concrete incorporating palm oil fuel ash

    Indian Academy of Sciences (India)

    HOSSEIN MOHAMMADHOSSEINI; A S M ABDUL AWAL; ABDUL RAHMAN MOHD SAM

    2016-10-01

    Prepacked aggregate concrete (PAC) is a special type of concrete which is made by placing coarse aggregate in a formwork and injecting a grout either by pump or under the gravity force to fill the voids. Use of pozzolanic materials in conventional concrete has become increasingly extensive, and this trend is expected to continue in PAC as well. Palm oil fuel ash (POFA) is one of these pozzolanic ash, which has been recognized as a good pozzolanic material. This paper presents the experimental results of the performance behaviour of POFA in developing physical and mechanical properties of prepacked aggregate concrete. Four concrete mixes namely,prepacked concrete with 100% OPC as a control, and PAC with 10, 20 and 30% POFA were cast, and thetemperature growth due to heat of hydration and heat transfer in all the mixtures was recorded. It has been found that POFA significantly reduces the temperature rise in prepacked aggregate concrete and delay the transfer of heat to the concrete body. The compressive and tensile strengths, however, increased with replacement up to20% POFA. The results obtained and the observation made in this study suggest that the replacement of OPC by POFA is beneficial, particularly for prepacked mass concrete where thermal cracking due to extreme heat rise is of great concern.

  11. Effect of nano materials in geopolymer concrete

    Directory of Open Access Journals (Sweden)

    Sudipta Naskar

    2016-09-01

    Full Text Available In general, cement based concrete can be replaced by low calcium fly-ash based geopolymer concrete regarding the adverse effect of the manufacture of ordinary Portland cement on environment. Nowadays, nano technology has an important role in the field of construction industries. It has been seen that several properties of cement based concrete are affected by different nano materials. As low calcium fly-ash based geopolymer concrete is an alternate option for cement based concrete, nano materials may also have some influence on it. An experimental program has been taken up on low calcium fly-ash based M25 grade geopolymer concrete having 16 (M concentration of activator liquid. Different percentage of nano materials viz. nano silica, carbon nano tube, titanium di-oxide were also used to investigate the effect of nano materials on geopolymer concrete. Geopolymer concrete with 1% titanium di-oxide shows appreciable improvement in compressive strength although pH remains almost same in all cases.

  12. Evaluating damage potential of cryogenic concrete using acoustic emission sensors and permeability testing

    Science.gov (United States)

    Kogbara, Reginald B.; Parsaei, Boback; Iyengar, Srinath R.; Grasley, Zachary C.; Masad, Eyad A.; Zollinger, Dan G.

    2014-04-01

    This study evaluates the damage potential of concrete of different mix designs subjected to cryogenic temperatures, using acoustic emission (AE) and permeability testing. The aim is to investigate design methodologies that might be employed to produce concrete that resists damage when cooled to cryogenic temperatures. Such concrete would be suitable for primary containment of liquefied natural gas (LNG) and could replace currently used 9% Ni steel, thereby leading to huge cost savings. In the experiments described, concrete cubes, 150 mm x 150 mm x 150 mm, were cast using four different mix designs. The four mixes employed siliceous river sand as fine aggregate. Moreover, limestone, sandstone, trap rock and lightweight aggregate were individually used as coarse aggregates in the mixes. The concrete samples were then cooled from room temperature (20°C) to cryogenic temperature (-165°C) in a temperature chamber. AE sensors were placed on the concrete cubes during the cryogenic freezing process. The damage potential was evaluated in terms of the growth of damage as determined from AE, as a function of temperature and concrete mixture design. The damage potential observed was validated with water permeability testing. Initial results demonstrate the effects of the coefficient of thermal expansion (CTE) of the aggregates on damage growth. Concrete damage (cracking) resistance generally decreased with increasing coarse aggregate CTE, and was in the order, limestone ≥ trap rock concrete due to differential CTE of its components.

  13. Enhancements in Magnesium Die Casting Impact Properties

    Energy Technology Data Exchange (ETDEWEB)

    David Schwam; John F. Wallace; Yulong Zhu; Srinath Viswanathan; Shafik Iskander

    2000-06-30

    The need to produce lighter components in transportation equipment is the main driver in the increasing demand for magnesium castings. In many automotive applications, components can be made of magnesium or aluminum. While being lighter, often times the magnesium parts have lower impact and fatigue properties than the aluminum. The main objective of this study was to identify potential improvements in the impact resistance of magnesium alloys. The most common magnesium alloys in automotive applications are AZ91D, AM50 and AM60. Accordingly, these alloys were selected as the main candidates for the study. Experimental quantities of these alloys were melted in an electrical furnace under a protective atmosphere comprising sulfur hexafluoride, carbon dioxide and dry air. The alloys were cast both in a permanent mold and in a UBE 315 Ton squeeze caster. Extensive evaluation of tensile, impact and fatigue properties was conducted at CWRU on permanent mold and squeeze cast test bars of AZ91, AM60 and AM50. Ultimate tensile strength values between 20ksi and 30ksi were obtained. The respective elongations varied between 25 and 115. the Charpy V-notch impact strength varied between 1.6 ft-lb and 5 ft-lb depending on the alloy and processing conditions. Preliminary bending fatigue evaluation indicates a fatigue limit of 11-12 ksi for AM50 and AM60. This is about 0.4 of the UTS, typical for these alloys. The microstructures of the cast specimens were investigated with optical and scanning electron microscopy. Concomitantly, a study of the fracture toughness in AM60 was conducted at ORNL as part of the study. The results are in line with values published in the literature and are representative of current state of the art in casting magnesium alloys. The experimental results confirm the strong relationship between aluminum content of the alloys and the mechanical properties, in particular the impact strength and the elongation. As the aluminum content increases from about 5

  14. Fibrous Calcareous Concretions in the Capsules of Human Pineal Glands

    OpenAIRE

    Kodaka Tetsuo; Mori Ryoichi; Ezure Hiromitsu; Ito Junji; Otsuka Naruhito

    2013-01-01

    We examined calcareous concretions in the capsule of 15 human pineal glands containing a large amount of the concretions in the matrix. The capsule concretions, brown to blackish-brown in color and/or translucent, were smaller than the matrix concretions, which were yellowish-white. The matrix concretions showed the typical mulberry-shaped overall appearance with scallop-shaped concentric laminations of non-fibrous structures, but the capsule concretions, which also contained Ca and P, showed...

  15. Sulfate attack and reinforcement corrosion in concrete with recycled concrete aggregates and supplementary cementing materials

    OpenAIRE

    Corral Higuera, Ramón; Arredondo Rea, Susana Paola; Neri Flores, M.A.; Gómez Soberón, José Manuel Vicente; Almeraya Calderón, F.; Castorena González, J.H.; Almaral Sánchez, Jorge Luis

    2011-01-01

    As strategies to contribute to the concrete industry sustainability, reinforced concrete was fabricated using recycled concrete coarse aggregate and replacing partially portland cement with supplementary cementing materials as fly ash and silica fume. On test specimens, partially immersed in 3.5% Na2SO4 aqueous solution, the effect of the recycled and supplementary materials against sulfate attack and reinforcement corrosion was evaluated. For such aim, weight loss of concrete and corrosion p...

  16. Current research progress in grain refinement of cast magnesium alloys: A review article

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Yahia; Qiu, Dong [School of Mechanical and Mining Engineering, University of Queensland, St Lucia, QLD 4072 (Australia); Jiang, Bin; Pan, Fusheng [College of Materials Science and Engineering, Chongqing University, Chongqing 400030 (China); Zhang, Ming-Xing, E-mail: Mingxing.Zhang@uq.edu.au [School of Mechanical and Mining Engineering, University of Queensland, St Lucia, QLD 4072 (Australia)

    2015-01-15

    Grain refinement of cast magnesium alloys, particularly in magnesium–aluminium (Mg–Al) based alloys, has been an active research topic in the past two decades, because it has been considered as one of the most effective approaches to simultaneously increase the strength, ductility and formability. The development of new grain refiners was normally based on the theories/models that were established through comprehensive and considerable studies of grain refinement in cast Al alloys. Generally, grain refinement in cast Al can be achieved through either inoculation treatment, which is a process of adding, or in situ forming, foreign particles to promote heterogeneous nucleation rate, or restricting grain growth by controlling the constitutional supercooling or both. But, the concrete and tangible grain refinement mechanism in cast metals is still not fully understood and there are a number of controversies. Therefore, most of the new developed grain refiners for Mg–Al based alloys are not as efficient as the commercially available ones, such as zirconium in non-Al containing Mg alloys. To facilitate the research in grain refinement of cast magnesium alloys, this review starts with highlighting the theoretical aspects of grain refinement in cast metals, followed by reviewing the latest research progress in grain refinement of magnesium alloys in terms of the solute effect and potent nucleants.

  17. Current research progress in grain refinement of cast magnesium alloys: A review article

    International Nuclear Information System (INIS)

    Grain refinement of cast magnesium alloys, particularly in magnesium–aluminium (Mg–Al) based alloys, has been an active research topic in the past two decades, because it has been considered as one of the most effective approaches to simultaneously increase the strength, ductility and formability. The development of new grain refiners was normally based on the theories/models that were established through comprehensive and considerable studies of grain refinement in cast Al alloys. Generally, grain refinement in cast Al can be achieved through either inoculation treatment, which is a process of adding, or in situ forming, foreign particles to promote heterogeneous nucleation rate, or restricting grain growth by controlling the constitutional supercooling or both. But, the concrete and tangible grain refinement mechanism in cast metals is still not fully understood and there are a number of controversies. Therefore, most of the new developed grain refiners for Mg–Al based alloys are not as efficient as the commercially available ones, such as zirconium in non-Al containing Mg alloys. To facilitate the research in grain refinement of cast magnesium alloys, this review starts with highlighting the theoretical aspects of grain refinement in cast metals, followed by reviewing the latest research progress in grain refinement of magnesium alloys in terms of the solute effect and potent nucleants

  18. The deformation of wax patterns and castings in investment casting technology

    Directory of Open Access Journals (Sweden)

    A. Herman

    2012-01-01

    Full Text Available The dimensional accuracy of the final casting of Inconel alloy 738 LC is affected by many aspects. One of them is the choice of method and time of cooling wax model for precision investment casting. The main objective was to study the initial deformation of the complex shape of the casting of the rotor blades. Various approaches have been tested for cooling wax pattern. When wax models are cooling on the air, without clamping in jig for cooling, deviations from the ideal shape of the casting are very noticeable (up to 8 mm and most are in extreme positions of the model. When blade is cooled in fixing jig in water environment, the resulting deviations compared with cooling in air are significantly larger, sometimes up to 10 mm. This itself does not mean that the final shape of the casting is dimensionally more accurate with usage of wax models, which have deviations from the ideal position smaller. Another deformation occurs when shell mould is produced around wax pattern and furthermore deformations emerge while casting of blade is cooling. This paper demonstrates first steps in describing complex process of deformations of Inconel alloy blades produced with investment casting technology by comparing results from thermal imagery, simulations in foundry simulation software ProCAST 2010 and measurements from CNC scanning system Carl Zeiss MC 850. Conclusions are so far not groundbreaking, but it seems deformations of wax pattern and deformations of castings do in some cases cancel each other by having opposite directions. Describing entirely whole process of deformations will help increase precision of blade castings so that models at the beginning and blades in the end are the same.

  19. 现场浇筑大坝混凝土起裂断裂韧度研究%Initial fracture toughness of site-casting dam concrete

    Institute of Scientific and Technical Information of China (English)

    管俊峰; 李庆斌; 吴智敏; 周绍武

    2014-01-01

    利用我国西南部某特高拱坝施工现场的拌合楼,浇筑成型骨料最大粒径150 mm的大坝混凝土楔入劈拉试件,试件尺寸分别为800 mm ×800 mm ×450 mm、1000 mm ×1000 mm ×450 mm和1200 mm ×1200 mm ×450 mm。通过试验获得现场浇筑大坝混凝土试件的起裂荷载,进而由有限元计算得到其起裂断裂韧度值,分析了龄期变化对起裂断裂韧度的影响规律,给出了起裂断裂韧度随试件尺寸的变化规律。结果表明,通过现场浇筑试件,得到大坝混凝土的起裂断裂韧度,能够真实反映大坝的实际断裂性能。现场浇筑大坝混凝土的起裂断裂韧度随着龄期增加而增加,180 d龄期的现场浇筑大坝混凝土的起裂断裂韧度在试件有效高度800~1200 mm范围内不存在明显的尺寸效应。%In this paper,the study aims to examine the initial fracture toughness KIinic of dam concrete ob⁃tained directly from a construction site. All test specimens with a maximum aggregate size of dmax = 150 mm were cast on site of an actual super-high arch dam in southwest China, and the dimensions of the wedge-splitting specimen were 800 mm × 800 mm × 450 mm,1000 mm × 1000 mm × 450 mm,1200 mm × 1200 mm × 450 mm, respectively. Based on the experimentally acquired initial cracking loads, the initial fracture toughness KI inic of the site-casting specimens was numerically obtained using the finite element method. Fur⁃thermore,the effect of specimen age and size on initial fracture toughness was analyzed and discussed. The results show that real fracture parameter KI inic of a super-high arch dam could be obtained by casting the test specimens at the construction site. The initial fracture toughness KI inic of the site-casting specimens in⁃creases with specimen age. The KI inic of the site-casting specimens at the age of 180 days is independent of specimen size at depths of 800 mm to 1200 mm.

  20. Radiation Damage In Reactor Cavity Concrete

    Energy Technology Data Exchange (ETDEWEB)

    Field, Kevin G [ORNL; Le Pape, Yann [ORNL; Naus, Dan J [ORNL; Remec, Igor [ORNL; Busby, Jeremy T [ORNL; Rosseel, Thomas M [ORNL; Wall, Dr. James Joseph [Electric Power Research Institute (EPRI)

    2015-01-01

    License renewal up to 60 years and the possibility of subsequent license renewal to 80 years has established a renewed focus on long-term aging of nuclear generating stations materials, and recently, on concrete. Large irreplaceable sections of most nuclear generating stations include concrete. The Expanded Materials Degradation Analysis (EMDA), jointly performed by the Department of Energy, the Nuclear Regulatory Commission and Industry, identified the urgent need to develop a consistent knowledge base on irradiation effects in concrete. Much of the historical mechanical performance data of irradiated concrete does not accurately reflect typical radiation conditions in NPPs or conditions out to 60 or 80 years of radiation exposure. To address these potential gaps in the knowledge base, The Electric Power Research Institute and Oak Ridge National Laboratory are working to disposition radiation damage as a degradation mechanism. This paper outlines the research program within this pathway including: (i) defining the upper bound of the neutron and gamma dose levels expected in the biological shield concrete for extended operation (80 years of operation and beyond), (ii) determining the effects of neutron and gamma irradiation as well as extended time at temperature on concrete, (iii) evaluating opportunities to irradiate prototypical concrete under accelerated neutron and gamma dose levels to establish a conservative bound and share data obtained from different flux, temperature, and fluence levels, (iv) evaluating opportunities to harvest and test irradiated concrete from international NPPs, (v) developing cooperative test programs to improve confidence in the results from the various concretes and research reactors, (vi) furthering the understanding of the effects of radiation on concrete (see companion paper) and (vii) establishing an international collaborative research and information exchange effort to leverage capabilities and knowledge.

  1. Effect Of Salt Water On Compressive Strength Of Concrete

    OpenAIRE

    Preeti Tiwari; Rajiv Chandak

    2014-01-01

    In this research work, the effect of salt water on the compressive strength of concrete was investigated. This paper therefore presents the result and findings of an experimental research on the effect of salt water on compressive strength of concrete. For this concrete cubes were cast using fresh wi and salt water for a design mix of M-30 1:1.8:3.31 by weight of concrete, and 0.45 water- cement ratio. Half of concrete cubes were cast and cured with fresh water and remaining ha...

  2. Effect Of Salt Water On Compressive Strength Of Concrete

    Directory of Open Access Journals (Sweden)

    Preeti Tiwari

    2014-04-01

    Full Text Available In this research work, the effect of salt water on the compressive strength of concrete was investigated. This paper therefore presents the result and findings of an experimental research on the effect of salt water on compressive strength of concrete. For this concrete cubes were cast using fresh wi and salt water for a design mix of M-30 1:1.8:3.31 by weight of concrete, and 0.45 water- cement ratio. Half of concrete cubes were cast and cured with fresh water and remaining half cubes were cast and cured with salt water. The concrete cubes were cured for 7,14 and 28 days respectively. The result of the average compressive strength of concrete obtained using fresh water ranges from 27.12 - 39.12N/mm2 and using salt water ranges from 28.45 – 41.34N/mm2

  3. Research on working property and early age mechanical property of self-compacting concrete used in steel-concrete structure

    International Nuclear Information System (INIS)

    Background: Self-compacting concrete that has good working property is the prerequisite of steel-concrete structure. The early age mechanical property of self-compacting concrete is the important parameter when design steel-concrete structure. Purpose: This paper attempts to research the working property and early age mechanical property of self-compacting concrete. Methods: Test is used to research the working property and early age mechanical property of self-compacting concrete. Results: Self-compacting concrete that could meet the requirement of steel-concrete structure has been mixed and parameters of early age mechanical property of self-compacting concrete which is necessary for design of steel-concrete structure have been presented. Conclusions: Base on the results, this paper can guide the construction of self-compacting concrete in steel-concrete structure and the design and construction of steel-concrete structure. (author)

  4. The optimization of concrete mixtures for use in highway applications

    Science.gov (United States)

    Moini, Mohamadreza

    Portland cement concrete is most used commodity in the world after water. Major part of civil and transportation infrastructure including bridges, roadway pavements, dams, and buildings is made of concrete. In addition to this, concrete durability is often of major concerns. In 2013 American Society of Civil Engineers (ASCE) estimated that an annual investment of 170 billion on roads and 20.5 billion for bridges is needed on an annual basis to substantially improve the condition of infrastructure. Same article reports that one-third of America's major roads are in poor or mediocre condition [1]. However, portland cement production is recognized with approximately one cubic meter of carbon dioxide emission. Indeed, the proper and systematic design of concrete mixtures for highway applications is essential as concrete pavements represent up to 60% of interstate highway systems with heavier traffic loads. Combined principles of material science and engineering can provide adequate methods and tools to facilitate the concrete design and improve the existing specifications. In the same manner, the durability must be addressed in the design and enhancement of long-term performance. Concrete used for highway pavement applications has low cement content and can be placed at low slump. However, further reduction of cement content (e.g., versus current specifications of Wisconsin Department of Transportation to 315-338 kg/m 3 (530-570 lb/yd3) for mainstream concrete pavements and 335 kg/m3 (565 lb/yd3) for bridge substructure and superstructures) requires delicate design of the mixture to maintain the expected workability, overall performance, and long-term durability in the field. The design includes, but not limited to optimization of aggregates, supplementary cementitious materials (SCMs), chemical and air-entraining admixtures. This research investigated various theoretical and experimental methods of aggregate optimization applicable for the reduction of cement content

  5. Bryce Canyon National Park: Hoodoos Cast Their Spell. Teaching with Historic Places.

    Science.gov (United States)

    Shakespear, Mala

    Surrounded by the beauty of southern Utah and panoramic views of three states, filigrees of colorful stones that erosion has shaped into a spectacular array of spires, fins, and pinnacles called "hoodoos" remind tourist viewers of church steeples, Gothic spires, castle walls, animals, and even people. In this lesson students explore why and how…

  6. Fermilab joins in global live Web cast

    CERN Multimedia

    Polansek, Tom

    2005-01-01

    From 2 to 3:30 p.m., Lederman, who won the Nobel Prize for physics in 1988, will host his own wacky, science-centered talk show at Fermi National Accelerator Laboratory as part of a lvie, 12-hour, international Web cast celebrating Albert Einstein and the world Year of Physics (2/3 page)

  7. The design of an instrumented rebar for assessment of corrosion in cracked reinforced concrete

    DEFF Research Database (Denmark)

    Pease, Bradley Justin; Geiker, Mette Rica; Stang, Henrik;

    2011-01-01

    An instrumented rebar is presented which was designed to have a realistic mechanical performance and to provide location dependent measurements to assess the environment with regards to reinforcement corrosion. The instrumented rebar was constructed from a hollowed 10 mm nominal diameter standard...... rebar with 17 electronically isolated corrosion sensors. Instrumented and standard rebars were cast into concrete beams and bending cracks were induced and held open using steel frames. Epoxy impregnation was used to assess and compare cracks in the concrete around the instrumented and standard rebar....... As bending-induced cracks reached the reinforcement, slip and separation occurred along the concrete-reinforcement interface. Cracks in the concrete surrounding standard and instrumented rebars are largely similar in appearance; however, sensors protruding from the instrumented rebar reduced the...

  8. Relation between fibre distribution and post-cracking behaviour in steel fibre reinforced self-compacting concrete panels

    OpenAIRE

    Abrishambaf, Amin; Barros, Joaquim A. O.; Cunha, Vitor M. C. F.

    2013-01-01

    In this research, the influence of the fibre distribution and orientation on the post-cracking behaviour of steel fibre 14 reinforced self-compacting concrete (SFRSCC) panels was studied. To perform this evaluation, SFRSCC panels 15 were cast from their centre point. For each SFRSCC panel, cylindrical specimens were extracted and notched either 16 parallel or perpendicular to the concrete flow direction, in order to evaluate the influence of fibre dispersion and 17 orientation on ...

  9. Undercooling and nodule count in thin walled ductile iron castings

    OpenAIRE

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2007-01-01

    Casting experiments have been performed with eutectic and hypereutectic castings with plate thicknesses from 2 to 8 mm involving both temperature measurements during solidification and microstructural examination afterwards. The nodule count was the same for the eutectic and hypereutectic castings in the thin plates (≤4.3 mm) while in the 8 mm plate the nodule count was higher in the hypereutectic than in the eutectic castings. The minimum temperature before the eutectic recalescence (Tmin) w...

  10. Combination of admixtures to improve the robustness of high-volume fly ash concrete in hot weather[ACI SP-239

    Energy Technology Data Exchange (ETDEWEB)

    Nkinamubanzi, P.C. [Natural Resources Canada, Ottawa, ON (Canada). CANMET International Centre for Sustainable Development of Cement and Concrete]|[American Concrete Inst. Farmington Hills, MI (United States); Bhattacharya, A.; Sharma, A. [Hindustan Construction Co., Mumbai (India)

    2006-07-01

    A precise admixtures system is needed when using high-volume fly ash concrete as fresh concrete occasionally undergoes rapid slump loss after mixing, which can cause problems with casting, pumping and finishing of the concrete in hot weather. This paper provided details of a study conducted to implement high-volume fly ash concrete technology in India. Different families of admixtures were investigated to determine their water reduction capacities. A set-retarding admixture was used in some of the concrete mixtures in order to determine its efficacy. An Indian Portland cement was used to create a total of 22 different concrete mixtures. Four different fly ashes were used to replace portions of the concrete. The slump of the fresh concrete mixture was monitored for 2 to 3 hours. Unit weight and temperature of the concrete was measured. Specimens were cast in steel moulds in order to determine the compressive strength and unit weight of the hardened concrete. The concretes were demoulded after 24 hours and cured in a water tank. Results of the study showed that 4 concrete mixtures showed good slump retention after 2 hours. The concretes were made using a combination of polycarboxylate-based admixtures from the naphthalene family. Concrete mixtures using admixtures made from sulfonated polymers also showed good slump resistance. Results showed that the selection of good combinations of admixtures can lead to excellent high volume fly ash concrete mixtures that are resistant to hot weather conditions. Exceptional results were achieved with concrete mixtures using a combination of polycarboxylates-based superplasticizers and sulfonated mid-range water-reducing admixtures. 7 refs., 8 tabs., 3 figs.

  11. Design of polymeric capsules for autonomous healing of cracks in cementitious materials

    OpenAIRE

    HILLOULIN, Benoit; Van Tittelboom, Kim; Gruyaert, Elke; LOUKILI, Ahmed; De Belie, Nele

    2013-01-01

    Now, most of the capsules used to contain polymeric healing agents in self-healing concrete, are made of glass. However, glass capsules cannot be mixed in concrete and are therefore placed manually into the moulds during concrete casting in laboratory tests. This represents a major drawback for an eventual industrialisation. In this study, polymeric capsules were designed to meet three requirements: breakage upon crack appearance, compatibility with the polymeric healing agent and survival...

  12. Mini Seminar on Form Filling Ability of Self-Compacting Concrete

    DEFF Research Database (Denmark)

    Thrane, Lars Nyholm

    2005-01-01

    The Nordic mini-seminar “Form Filling Ability of Self-Compacting Concrete” took place on 3-4 November 2003 at the Danish Technological Institute in Taastrup, Denmark. The mini-seminar gathered 12 participants from Finland, Sweden, Norway and Denmark. The objective was to present and discuss recent...... developments of Self-Compacting Concrete in the Nordic countries. In general, the seminar included results and observations on the effect of fresh concrete behaviour, casting technique, and organisation on site on the filling ability, passing ability, and surface quality. The seminar had participants from the...

  13. Caste dominance and economic performance in rural India

    NARCIS (Netherlands)

    Kalwij, Adriaan; Iversen, Vegard; Verschoor, Arjan; Dubey, Amaresh

    2014-01-01

    Using household panel data for rural India covering 1993–94 and 2004–5, we test whether scheduled castes (SCs) and other minority groups perform better or worse in terms of income when resident in villages dominated by (i) upper castes or (ii) their own group. Theoretically, upper-caste dominance co

  14. Controlling Air Content in Concrete That is Being Pumped, A Synthesis Study

    OpenAIRE

    Scholer, Charles F.; Grossman, Jay

    1998-01-01

    Changes in the air content of fresh concrete that is being pumped can occur at a number of places. These locations include the initial loading of the concrete into the pump hopper, as it passes through the pump line, and when it exits the line. This synthesis reviews the findings of recent research studies which deal with air content change in pumped concrete and summarizes methods of reducing air loss caused by handling. Three main mechanisms by which air content is lost in fresh concrete th...

  15. Fatigue in Breakwater Concrete Armour Units

    DEFF Research Database (Denmark)

    Burcharth, Hans F.

    1985-01-01

    The reliability of rubble mound breakwaters depends on the hydraulic stability and the mechanical strength of the armour units. The paper deals with the important aspect of fatigue related to the strength of concrete armour units. Results showing significant fatigue from impact tests with Dolosse...... made of unreinforced and steel fibre reinforced flyash concrete are presented. Moreover universal graphs for fatigue in armour units made of conventional unreinforced concrete exposed to impact load and pulsating load are presented. The effect of fibre reinforcement and the implementation of fatigue in...

  16. Variable Geometry Casting of Concrete Elements Using Pin-Type Tooling

    DEFF Research Database (Denmark)

    Pedersen, Troels Holm; Lenau, Torben Anker

    2010-01-01

    Background: Today, free form parts are made in small production volume with time consuming methods and a significant amount of material waste. These methods include CNC machining and the layered rapid prototyping techniques SLA, SLS, FDM, 3D print etc., which are well suited for smaller parts...

  17. Shear strength of match cast dry joints of precast concrete segmental bridges: proposal for Eurocode 2

    Directory of Open Access Journals (Sweden)

    Aparicio, J. A.

    2006-06-01

    Full Text Available This paper discusses a study on the performance of concretesegmental bridges with shear keys, focusing on theshear behaviour of castellated dry joints under ultimatelimit state conditions. The widely varying formulationused to evaluate joint shear strength were compiled,along with the experimental results published in the literatureon the subject. The various approaches were evaluatedby comparing their predictions of ultimate jointstrength to published empirical findings. The formulagiving the best prediction was adapted to the safety factorprovisions set out in Eurocode 2.Este trabajo presenta un estudio sobre el comportamientode puentes de dovelas de hormigon con llaves de cortante,centrado en el comportamiento a cortante de lasjuntas secas conjugadas en Estado Limite Ultimo. Se harealizado una exhaustiva recopilacion de la dispar formulacionexistente para evaluar la resistencia a cortante delas juntas. Se ha realizado, asimismo, una investigacionbibliografica de los resultados experimentales disponiblessobre este particular en la literatura. Los resultados recogidosen la bibliografia han sido comparados con la variadaformulacion existente para predecir la resistencia ultimade las juntas. La formula que mejor predice laresistencia ha sido identificada. Esta ha sido adaptada alformato de seguridad presente en el Eurocodigo 2.

  18. Application of numerical modeling at technology designing of heating and solidification of concrete in monolithic structures

    Directory of Open Access Journals (Sweden)

    L. V. Zinevich

    2011-03-01

    Full Text Available Questions of application of numerical modeling are considered at calculation temperature-strength conditions of concrete monolithic constructions, including in the environment of universal settlement package ELCUT. Processes of technological supply to heating and care of concrete belong to the main group of works for making cast-in-situ reinforced concrete structures in building conditions. They determine to a large extent their end-use properties and quality of building construction according to longevity and trustability criteria. Computer modeling possibility of these processes allows work out in high competitive and quality level complex of technological arrangements which can provide favorable conditions for concrete structures solidification according to the intensity required by building technology. But today one can find almost complete absence of tools – simple and available in all meanings which can allow automate thermotechnical calculations and select parameters of heating, and also difficult calculations of temperature and strength state of concrete in the construction modeling. In connection with this, engineering and introduction of special computer additions (small and simple enough including based on universal calculated complexes in project practice is the topical goal. In the article the general situation in the technological projecting of heating and care of concrete and two examples of projects implemented by author are considered. Special attention is paid on modeling of concrete position using Method of Final Elements in universal package ELCUT.

  19. Use of metallic fibers in concretes

    Directory of Open Access Journals (Sweden)

    Kherbache Souad

    2014-04-01

    Full Text Available The addition of a waste (fibers in construction materials, particularly, the concretes is a technique increasingly used, for several reasons, either ecological, or economic, or to improve some properties in a fresh or hardened state. In our work we studied the behavior of the concrete and the mortar containing metallic fibers resulting from the unit BCR which is in Bordj-Menaiel in Algeria (metallic fibers resulting from the rejection at the end of the domestic operation of silvering of the tools and which is stored in plastic bags which are preserved in metal containers. Our work consists to study the behavior of the concretes and the mortars containing these fibers of cement substitution. We noted that the use of these fibers in the concretes in substitution of cement decreases its of compressive strength and flexural strength but to 10% of waste these strength remain acceptable.

  20. RESEARCH AND APPLICATION OF AS-CAST WEAR RESISTANCE HIGH CHROMIUM CAST IRON

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The influence of alloy elements, such as boron and silicon, on the microstructure and properties of as-cast high chromium cast iron is studied. The results show that boron and silicon have a great effect on the mechanical properties and the wear resistance. Through proper addition of boron and silicon, the properties of as-cast high chromium cast iron can be improved effectively. Through analyzing the distribution of elements by scanning electron microscope, it has been shown that the addition of boron and silicon lowers the mass fraction of chromium saturated in as-cast austenite, and makes it unstable and liable to be transformed into martensite. The as-cast high chromium cast iron with proper content of boron and silicon is suitable for the manufacture of lining for asphalt concrete mixer and its wear resistance is 14 times that of lining made of low alloy white cast iron.

  1. Moisture redistribution in screeded concrete slabs

    OpenAIRE

    Åhs, Magnus

    2007-01-01

    The principal objective for this licentiate thesis is to develop a methodology and evaluation model in order to make the future relative humidity in a screeded concrete slab predictable. Residual moisture in screeded concrete slabs may redistribute to the top screed surface under semi-permeable flooring, thus elevating the relative humidity, RH, and possibly exceed the critical humidity level. Passing the critical humidity level may result in material damages on the flooring and adhesive. ...

  2. Performance of intact and partially degraded concrete barriers in limiting mass transport

    International Nuclear Information System (INIS)

    Mass transport through concrete barriers and release rate from concrete vaults are quantitatively evaluated. The thorny issue of appropriate diffusion coefficients for use in performance assessment calculations is covered, with no ultimate solution found. Release from monolithic concrete vaults composed of concrete waste forms is estimated with a semi-analytical solution. A parametric study illustrates the importance of different parameters on release. A second situation of importance is the role of a concrete shell or vault placed around typical waste forms in limiting mass transport. In both situations, the primary factor controlling concrete performance is cracks. The implications of leaching behavior on likely groundwater concentrations is examined. Frequently, lower groundwater concentrations can be expected in the absence of engineered covers that reduce infiltration

  3. Topics in Cement and Concrete Research

    OpenAIRE

    Brouwers, H. J. H.

    2006-01-01

    The present paper addresses several topics in regard to the sustainable design and use of concrete. First, major features concerning the sustainable aspects of the material concrete are summarised. Then the major constituent, from an environmental point of view, cement is discussed in detail, particularly the hydration and application of slag cement. The intelligent combining of mineral oxides, which are found in clinker, slag, fly ashes etc., is designated as mineral oxide engineering. It re...

  4. Utilization of Electronic Waste Plastic in Concrete

    Directory of Open Access Journals (Sweden)

    Vivek S. Damal

    2015-04-01

    Full Text Available In India, bitumen pavements are commonly used for highways. Due to the increasing traffic intensity, distress such as rutting and cracking of pavements are very common in Indian roads. Under varying seasonal temperature, flexible pavements tend to become soft in summer and brittle in winter. Investigations revealed that properties of concrete can be better than bitumen roads. But now a day‟s concrete roads are used commonly because concrete roads have more life span than the bitumen roads. In large cities now a day‟s concrete roads are used because concrete roads are more durable, strengthen and having more life span than bitumen roads. Waste plastics and E-waste (electronic waste both by domestic and industrial sectors can be used in the production of asphalt mix. Waste plastic, mainly used for packing are made up of polyethylene, polypropylene, polystyrene. Electronic waste, abbreviated as e-waste, consists of discarded old computers, TVs, refrigerators; radios, etc are basically any electrical or electronic appliance that has reached its end of life. An experimental study is made on the utilization of E-waste particles as fine aggregates in concrete with a percentage replacement ranging from 0 % to 21.5% i.e. (7.5%, 15% and 21.5% on the strength criteria of M30 Concrete. Compressive strength Concrete with and without E- waste plastic as aggregates was observed which exhibits a good strength. The feasibility of utilizing E-waste plastic particles as partial replacement of fine aggregate has been presented. In the present study, compressive strength was investigated for Optimum Cement Content and 7.5% E-plastic content in mix yielded stability and very good in compressive strength of 43 grade cement.

  5. Structure and mechanical properties of vermicular cast iron in cylinder head casting

    Directory of Open Access Journals (Sweden)

    E. Guzik

    2009-01-01

    Full Text Available The paper discusses the problem of grain density and ferrite content in microstructure of vermicular graphite iron cast in bars of different section diameters and cylinder head casting. The experimental results regarding the section effect demonstrate that the nodule count, grain density and ferrite content are all function of the cast bar diameter in this particular case ranging from 0.6 to 8.0 cm and microstructure and mechanical properties in the cylinder head. The nodule count (or grain density has been reported to increase, while ferrite content was decreasing with decreasing casting diameter. The density number of the grains Nv has been related (by regression analysis to the undercooling degree

  6. Establishment of mathematical moment model in twin casting rolling rolls

    Institute of Scientific and Technical Information of China (English)

    孙斌煜; 苑世剑; 张洪; 杜艳平; 张芳萍

    2002-01-01

    In continuous casting rolling process, the deformed body is different from the hot rolling strip. The metal in casting rolling zone is first assumed to be viscous fluid and the mathematical model of casting rolling force is established, then the calculating formula for casting rolling torque is derived. In addition, considering the effects of deforming cone and appendant torque of rotary junctions sealing ring, the calculating model which accords with casting rolling condition is found out. Theoretical formula is proved by experiment.

  7. PLACE OF NUTRITION IN YOGA

    OpenAIRE

    Desai, B.P.

    1990-01-01

    Nutrition plays a very vital role in our life. Yoga and Ayurveda had laid down the foundations of dietetics. The valuable guidelines regarding various food articles and diet for Yoga Sadhaka, to achieve maximum benefits, are given in traditional yoga texts like Hatha Pradipika and Gheranda Samhitha. Now is the time to evaluate the place of nutrition in Yoga and to study how the dietetic principles in yoga will help to eradicate the national problem of Mal-nutrition and poverty which is the pr...

  8. Undercooling and nodule count in thin walled ductile iron castings

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2007-01-01

    Casting experiments have been performed with eutectic and hypereutectic castings with plate thick¬nesses from 2 to 8 mm involving both temperature measurements during solidification and micro¬structural examination afterwards. The nodule count was the same for the eutectic and hypereutectic...... castings in the thin plates ( 4.3 mm) while in the 8 mm plate the nodule count was higher in the hypereutectic than in the eutectic castings. The minimum temperature prior to the eutectic recalescence (Tmin) was 15 to 20C lower for the eutectic than the hypereutectic castings. This is due to nucleation...... of graphite nodules which begins at a lover temperature in the eutectic than in the hypereutectic castings The recalescence (Trec) was however also larger for the eutectic casting and in the thin plates the maximum temperature after recalescence (Tmax) was the same in the eutectic and hypereutectic...

  9. Undercooling and nodule count in thin walled ductile iron castings

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2007-01-01

    Casting experiments have been performed with eutectic and hypereutectic castings with plate thicknesses from 2 to 8 mm involving both temperature measurements during solidification and microstructural examination afterwards. The nodule count was the same for the eutectic and hypereutectic castings...... in the thin plates (≤4.3 mm) while in the 8 mm plate the nodule count was higher in the hypereutectic than in the eutectic castings. The minimum temperature before the eutectic recalescence (Tmin) was 15 to 20ºC lower for the eutectic than for the hypereutectic castings. This is due to nucleation of...... graphite nodules which begins at a lower temperature in the eutectic than in the hypereutectic castings. The recalescence ∆Trec was however also larger for the eutectic casting and in the thin plates the maximum temperature after recalescence (Tmax) was the same in the eutectic and hypereutectic plates...

  10. Recent development of ductile cast iron production technology in China

    Institute of Scientific and Technical Information of China (English)

    Cai Qizhou; Wei Bokang

    2008-01-01

    Recent progress in the production and technology of ductile cast iron castings in China is reviewed.The manufacture and process control of as-cast ductile iron are discussed.The microstructure.properties and application of partial austenitization normalizing ductile iron and austempered duclile iron(ADI)are briefly depicted.The new development of duclile iron production techniques,such as cored-wire injection(wire-feeding nodularization)process,tundish cover ladle nodularizing process,horizontal continuous casting,and EPC process (lost foam)for ductile iron castings,etc.,are summarized.

  11. Organic compounds in concrete from demolition works.

    Science.gov (United States)

    Van Praagh, M; Modin, H; Trygg, J

    2015-11-01

    This study aims to verify the effect of physically removing the outer surface of contaminated concrete on total contents and on potential mobility of pollutants by means of leaching tests. Reclaimed concrete from 3 industrial sites in Sweden were included: A tar impregnated military storage, a military tar track-depot, as well as concrete constructions used for disposing of pesticide production surplus and residues. Solid materials and leachates from batch and column leaching tests were analysed for metals, Cl, F, SO4, DOC and contents of suspected organic compounds (polycyclic aromatic hydrocarbons, PAH, and pesticides/substances for pesticide production such as phenoxy acids, chlorophenols and chlorocresols, respectively). In case of PAH contaminated concrete, results indicate that removing 1 or 5 mm of the surface lead to total concentrations below the Swedish guidelines for recycling of aggregates and soil in groundwork constructions. 3 out of 4 concrete samples contaminated with pesticides fulfilled Swedish guidelines for contaminated soil. Results from batch and column leaching tests indicated, however, that concentrations above environmental quality standards for certain PAH and phenoxy acids, respectively, might occur at site when the crushed concrete is recycled in groundwork constructions. As leaching tests engaged in the study deviated from leaching test standards with a limited number of samples, the potential impact of the leaching tests' equipment on measured PAH and pesticide leachate concentrations has to be evaluated in future work. PMID:26164853

  12. Organic compounds in concrete from demolition works.

    Science.gov (United States)

    Van Praagh, M; Modin, H; Trygg, J

    2015-11-01

    This study aims to verify the effect of physically removing the outer surface of contaminated concrete on total contents and on potential mobility of pollutants by means of leaching tests. Reclaimed concrete from 3 industrial sites in Sweden were included: A tar impregnated military storage, a military tar track-depot, as well as concrete constructions used for disposing of pesticide production surplus and residues. Solid materials and leachates from batch and column leaching tests were analysed for metals, Cl, F, SO4, DOC and contents of suspected organic compounds (polycyclic aromatic hydrocarbons, PAH, and pesticides/substances for pesticide production such as phenoxy acids, chlorophenols and chlorocresols, respectively). In case of PAH contaminated concrete, results indicate that removing 1 or 5 mm of the surface lead to total concentrations below the Swedish guidelines for recycling of aggregates and soil in groundwork constructions. 3 out of 4 concrete samples contaminated with pesticides fulfilled Swedish guidelines for contaminated soil. Results from batch and column leaching tests indicated, however, that concentrations above environmental quality standards for certain PAH and phenoxy acids, respectively, might occur at site when the crushed concrete is recycled in groundwork constructions. As leaching tests engaged in the study deviated from leaching test standards with a limited number of samples, the potential impact of the leaching tests' equipment on measured PAH and pesticide leachate concentrations has to be evaluated in future work.

  13. Solidification and casting

    CERN Document Server

    Cantor, Brian

    2002-01-01

    INDUSTRIAL PERSPECTIVEDirect chillcasting of aluminium alloysContinuous casting of aluminium alloysContinuous casting of steelsCastings in the automotive industryCast aluminium-silicon piston alloysMODELLING AND SIMULATIONModelling direct chill castingMold filling simulation of die castingThe ten casting rulesGrain selection in single crystal superalloy castingsDefects in aluminium shape castingPattern formation during solidificationPeritectic solidificationSTRUCTURE AND DEFECTSHetergeneous nucleation in aluminium alloysCo

  14. Maintenance system improvement in cast iron foundry

    OpenAIRE

    S. Kukla

    2011-01-01

    The work presents the issue of technical equipment management in an iron foundry basing on the assumptions of the TPM system (Total Productive Maintenance). Exploitation analysis of automatic casting lines has been carried out and their work’s influence on the whole production system’s functioning has been researched. Within maintenance system improvement, implementation of autonomic service and planned lines’ review have been proposed in order to minimize the time of breakdown stoppages. The...

  15. CASTING OF DETAILS OF WEAR-RESISTANT CHROME CAST IRONS FOR CHROMIC MILLS IN COMBINED MOLDS AND CHILLS

    Directory of Open Access Journals (Sweden)

    K. E. Baranovskij

    2009-01-01

    Full Text Available Relative wear resistance of chrome cast irons of eutectic composition is determined in laboratory and industry conditions. Complex alloyed eutectic cast iron with increased wear resistance and mechanical characteristics is developed.

  16. Use of Recycled Aggregate and Fly Ash in Concrete Pavement

    Directory of Open Access Journals (Sweden)

    Myle N. James

    2011-01-01

    Full Text Available Problem statement: Recycled materials aggregate from the demolished concrete structures and fly ash from burning coal shows the possible application as structural and non structural components in concrete structures. This research aims to evaluate the feasibility of using concrete containing recycled concrete aggregate and fly ash in concrete pavement. Approach: Two water cement ratio (0.45 and 0.55 the compressive strength, modulus of electricity and flexural strength for concrete with recycled aggregate and fly ash with 0, 25% replacing cement in mass were considered. Results: The material properties of recycled aggregate concrete with fly ash indicate comparable results with that of concrete with natural aggregate and without fly ash. Conclusion/Recommendations: The recycled materials could be used in concrete pavement and it will promote the sustainability of concrete.

  17. Phase Transformation in Cast Superaustenitic Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Lee Phillips, Nathaniel Steven [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    Superaustenitic stainless steels constitute a group of Fe-based alloys that are compositionally balanced to have a purely austenitic matrix and exhibit favorable pitting and crevice corrosion resistant properties and mechanical strength. However, intermetallic precipitates such as sigma and Laves can form during casting or exposure to high-temperature processing, which degrade the corrosion and mechanical properties of the material. The goal of this study was to accurately characterize the solid-solid phase transformations seen in cast superaustenitic stainless steels. Heat treatments were performed to understand the time and temperature ranges for intermetallic phase formations in alloys CN3MN and CK3MCuN. Microstructures were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy and wavelength dispersive spectroscopy (EDS, WDS). The equilibrium microstructures, composed primarily of sigma and Laves within purely austenitic matrices, showed slow transformation kinetics. Factors that determine the extent of transformation, including diffusion, nucleation, and growth, are discussed.

  18. Solidification control in continuous casting of steel

    Indian Academy of Sciences (India)

    S Mazumdar; S K Ray

    2001-02-01

    An integrated understanding of heat transfer during solidification, friction/lubrication at solid-liquid interface, high temperature properties of the solidifying shell etc. is necessary to control the continuous casting process. The present paper elaborates upon the knowledge developed in the areas of initial shell formation, mode of mould oscillation, and lubrication mechanism. The effect of these issues on the caster productivity and the quality of the product has been discussed. The influence of steel chemistry on solidification dynamics, particularly with respect to mode of solidification and its consequence on strength and ductility of the solidifying shell, has been dealt with in detail. The application of these basic principles for casting of stainless steel slabs and processing to obtain good quality products have been covered.

  19. Understanding the Self Compacting Concrete & Its Fresh Properties

    OpenAIRE

    Prof. Vatsal Patel 1 ,; Prof. Nirav Gajjar 2

    2014-01-01

    A new kind of high performance concrete (HPC) i.e. self compacting concrete has been first developed in Japan in 1986. The development of SCC has made casting of dense reinforcement and mass concrete convenient, has minimized noise. Fresh self-compacting concrete (SCC) flows into formwork and around obstructions under its own weight to fill it completely and self-compact (without any need for vibration), without any segregation and blocking. The elimination of the need for com...

  20. How Concrete Is Concrete?

    Science.gov (United States)

    Gravemeijer, Koeno

    2011-01-01

    If we want to make something concrete in mathematics education, we are inclined introduce, what we call, "manipulatives", in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own,…

  1. Modelling of the fracture toughness anisotropy in fiber reinforced concrete

    OpenAIRE

    Tarasovs, S.; J. Krūmiņš; V. Tamužs

    2016-01-01

    Steel fiber reinforced concrete is potentially very promising material with unique properties, which currently is widely used in some applications, such as floors and concrete pavements. However, lack of robust and reliable models of fiber reinforced concrete fracture limits its application as structural material. In this work a numerical model is proposed for predicting the crack growth in fiber reinforced concrete. The mixing of the steel fibers with the concrete usually creates...

  2. Preferential dissolution behaviour in Ni–Cr dental cast alloy

    Indian Academy of Sciences (India)

    Viswanathan S Saji; Han Cheol Choe

    2010-08-01

    A Ni–Cr–Mo dental alloy was fabricated by three different casting methods, viz. centrifugal casting, high frequency induction casting and vacuum pressure casting. The dependence of cast microstructure on the electrochemical corrosion behaviour was investigated using potentiodynamic cyclic and potentiostatic polarization techniques, impedance spectroscopy and scanning electron microscopy. The experimental results were compared and discussed with those obtained for a Co–Cr–Mo counterpart. The results of the study showed that the variation in casting morphologies with casting methods has only marginal influence in the overall corrosion resistance of Ni–Cr and Co–Cr dental alloys. There was severe preferential dissolution of Ni rich, Cr and Mo depleted zones from the Ni–Cr–Mo alloy. The overall corrosion resistance property of the Co–Cr base alloy was better than that of the Ni–Cr base alloy.

  3. Myoglobin casts in renal biopsies: immunohistochemistry and morphologic spectrum.

    Science.gov (United States)

    Liapis, Helen; Boils, Christie; Hennigar, Randolph; Silva, Fred

    2016-08-01

    Five hundred eighty renal biopsies from a pool of 27850 archived cases were identified in which a myoglobin stain was performed because of atypical casts. Two hundred and thirty-eight (41%) of these biopsies were found to be positive for myoglobin casts. The morphology of the myoglobin casts ranged from light, almost translucent and refractile, to pink, to dark red and slightly brown granular casts by hematoxylin and eosin, to beaded globular casts that stained brightly fuchsinophilic with Masson trichrome and partially argyrophilic with silver methenamine. All biopsies displayed acute tubular injury associated with intratubular debris and thinning and vacuolization of tubular epithelium. Approximately 20% of myoglobin-positive biopsies showed calcium oxalate or phosphate deposition. Positive myoglobin staining was present in casts, proximal tubular epithelial cells without casts, and also dehisced epithelial cells. Collecting ducts and occasionally the distal tubular epithelium also stained positive. One case showed concurrent myeloma cast nephropathy with "fractured" casts and translucent myoglobin-positive casts. Herein, we describe the morphologic spectrum of myoglobin-positive casts. We conclude that utilization of myoglobin immunohistochemistry is advantageous and, when not available, knowledge of the morphologic spectrum is important. PMID:27038680

  4. Use of Recycled Aggregate and Fly Ash in Concrete Pavement

    OpenAIRE

    Myle N. James; Wonchang Choi; Taher Abu-Lebdeh

    2011-01-01

    Problem statement: Recycled materials aggregate from the demolished concrete structures and fly ash from burning coal shows the possible application as structural and non structural components in concrete structures. This research aims to evaluate the feasibility of using concrete containing recycled concrete aggregate and fly ash in concrete pavement. Approach: Two water cement ratio (0.45 and 0.55) the compressive strength, modulus of electricity and flexural streng...

  5. The optimization of concrete mixtures for use in highway applications

    Science.gov (United States)

    Moini, Mohamadreza

    Portland cement concrete is most used commodity in the world after water. Major part of civil and transportation infrastructure including bridges, roadway pavements, dams, and buildings is made of concrete. In addition to this, concrete durability is often of major concerns. In 2013 American Society of Civil Engineers (ASCE) estimated that an annual investment of 170 billion on roads and 20.5 billion for bridges is needed on an annual basis to substantially improve the condition of infrastructure. Same article reports that one-third of America's major roads are in poor or mediocre condition [1]. However, portland cement production is recognized with approximately one cubic meter of carbon dioxide emission. Indeed, the proper and systematic design of concrete mixtures for highway applications is essential as concrete pavements represent up to 60% of interstate highway systems with heavier traffic loads. Combined principles of material science and engineering can provide adequate methods and tools to facilitate the concrete design and improve the existing specifications. In the same manner, the durability must be addressed in the design and enhancement of long-term performance. Concrete used for highway pavement applications has low cement content and can be placed at low slump. However, further reduction of cement content (e.g., versus current specifications of Wisconsin Department of Transportation to 315-338 kg/m 3 (530-570 lb/yd3) for mainstream concrete pavements and 335 kg/m3 (565 lb/yd3) for bridge substructure and superstructures) requires delicate design of the mixture to maintain the expected workability, overall performance, and long-term durability in the field. The design includes, but not limited to optimization of aggregates, supplementary cementitious materials (SCMs), chemical and air-entraining admixtures. This research investigated various theoretical and experimental methods of aggregate optimization applicable for the reduction of cement content

  6. In-plane shear test of fibre reinforced concrete panels

    DEFF Research Database (Denmark)

    Solgaard, Anders Ole Stubbe; Stang, Henrik; Goltermann, Per

    2008-01-01

    The present paper concerns the investigation of polymer Fiber Reinforced Concrete (FRC) panels subjected to in-plane shear. The use of fibers as primary reinforcement in panels is a new application of fiber reinforcement, hence test methods, design bases and models are lacking. This paper...... contributes to the investigation of fibers as reinforcement in panels with experimental results and a consistent approach to material characterization and modeling. The proposed model draws on elements from the classical yield line theory of rigid, perfectly plastic materials and the theory of fracture...... determined from wedge splitting test (WST) specimens and compression cylinders. Three different test series were cast, where the only parameter which was varied was the amount of fibers in the mix, viz. 0.5, 1.0 and 1.5 vol. % fibers, respectively. Three identical experiments with panels were carried out...

  7. Recycling of fresh concrete exceeding and wash water in concrete mixing plants

    OpenAIRE

    Férriz Papí, J. A.

    2014-01-01

    The exceeding concrete and washing equipment water are a matter to solve in concrete production. This paper explains several possibilities for recycling and analyses the products obtained with one recycling equipment. The objective of this work is to study the possibility to increase the percentage of recycling in new mixes. The developed study relates wash water density and fine particles content. Besides, mortar and concrete samples were tested introducing different quantities of these fine...

  8. INVESTIGATIONS ON RECYCLED CONCRETE AGGREGATE AND MSAND AS AGGREGATE REPLACEMENT IN CONCRETE

    OpenAIRE

    Sridhar, U; Karthick, B

    2015-01-01

    Gigantic numbers of building and destruction trashes are produced in emerging countries like India. The clearance of these trashes is serious problem because it requires huge space. The present work is to study the properties of concrete with replacement of 50% of nature sand by manufactured sand and coarse aggregates by different proportions with recycled concrete aggregates (RCA). A mix proportion for M20 grade concrete is derived with standards confirming to IS codes. RCA was p...

  9. Development and optimization of novel sensors for inline measurement of sand filling and compaction stages in lost foam casting

    Science.gov (United States)

    Whelan, Matthew J.; Janoyan, Kerop D.

    2005-05-01

    The lost foam casting (LFC), or expendable pattern casting, process is employed worldwide in foundries as an efficient casting technology that offers the advantages of consolidation of components, reduced machining, and recirculation of casting mold material. Currently, many foundries develop a schedule of sand raining flow rates and flask excitation accelerations for each specific pattern through an often-lengthy trial and error procedure. During casting, a single flask acceleration measurement is typically the only measurement by which the sand compaction is monitored. The current research focuses on developing an array of measurement tools to be used in measuring parameters critical to the sand compaction stage of the lost foam casting process to aid in the development of filling and vibration schedules as well as to provide additional inline measurements during foundry operation. In particular, the study focuses on the use of minimally intrusive transducers placed inline to provide direct feedback that can be then used in both passive and active process control.

  10. State of the Art Treatment of Non-Ferrous Castings 3-in-1 Heat Treatment Systems Combine Foundry Processes

    Institute of Scientific and Technical Information of China (English)

    Volker R. Knobloch

    2004-01-01

    The interior of a high-pressure die-casting is of an unsatisfactory quality. Engine blocks made with this die casting process show lower specific engine performance. Pressure die-casting can hardly be heat treated for obvious reasons.PSM (Precision Sand Molds) process uses sand and organic binder to generate a mold and even allows the manufacturing of complex diesel engine blocks in aluminum alloys. Combined technologies are available for semi-permanent mold castings with cores and castings made in Precision Sand Molds with organic binders. Castings are placed into the special heat treatment furnace immediately after pouring without the operations in stand alone machinery. This patented Sand Lion(R) 3-in-1 technology processes hot castings and carries out three (3) foundry processes simultaneously in one (1) automated machine: 1) De-coring and sand removal; 2) Thermal sand reclamation; 3) Solution heat treatment of castings. The combination of several main casting processes is reflected in significant reductions of energy consumption, of production costs, and improving the quality of the castings. Audits in foundries using the 3-in-1 process showed an average reduction in production costs of more than 30%.

  11. Comparison of Performance of Standard Concrete And Fibre Reinforced Standard Concrete Exposed To Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    K.Srinivasa Rao

    2013-01-01

    Full Text Available Concrete elements exposed to fire undergo temperature gradients and as a result, undergo physical changes or spalling which leads to expose steel reinforcement. This causes distress in concrete structures. The performance of concrete can be improved with the addition of steel fibres to concrete especially when it is exposed to heat. Therefore, this study has been carried out to generate experimental data on standard concrete ofgrade M45 and Fiber Reinforced Standard Concrete exposed to elevated temperatures. For each type of concrete six sets of cubes, cylinders, and beams have been cast. Each set contains 5specimens. A total of thirty cubes, thirty cylinders, and thirty beams of Standard Concrete and Fiber Reinforced Standard Concrete have been cast, out of which 5 sets of standard concrete and fiber reinforced standard concrete are exposed to elevated temperatures of 500C, 1000C, 1500C, 2000C and 2500C for 3 hours and the sixth set is tested at room temperature as control concrete. These specimens have been tested for compressive strength, split tensile strength, and flexural strength in hot condition immediately after taking out from oven. The results are analyzed and final conclusions are drawn.

  12. Contribution of mesoscopic modeling for flows prediction in cracked concrete buildings in condition of severe accident

    International Nuclear Information System (INIS)

    This Ph.D. thesis aims at characterising and modeling the mechanical behavior of concrete at the mesoscopic scale. The more general scope of this study is the development of mesoscopic model for concrete; this model is to represent the concrete as a heterogeneous medium, taking into account the difference between aggregate and cement paste respecting the grading curve, the model parameters describe the mechanical and thermal behavior of cement paste and aggregates. We are interested in understanding the concrete behaviour, considered one structure. A program of random granular structure valid in 2D and 3D has been developed. This program is interfaced with the Finite Element code CAST3M in order to compute the numerical simulations. A method for numerical representation of the inclusions of concrete was also developed and validated by projection of the geometry on the shape functions, thus eliminating the problems of meshing that made the representation of all aggregates skeleton almost impossible, particularly in 3D. Firstly, the model is studied in two-dimensional and three-dimensional in order to optimize the geometrical model of the inner structure of concrete in terms of the meshing strategy and the smallest size of the aggregate to be taken into account. The results of the 2D and 3D model are analyzed and compared in the case of uniaxial tension and uniaxial compression. The model used is an isotropic unilateral damage model from Fichant [Fichant et al., 1999]. The model allows to simulate both the macroscopic behavior but also with the local studies of the distribution of crack and crack opening. The model shows interesting results on the transition from diffuse to localized damage and is able to reproduce dilatancy in compression. Finally, the mesoscopic model is applied to three simulations: the calculation of the permeability of cracked concrete; the simulation of the hydration of concrete at early age and finally the scale effect illustrated by bending

  13. Performance polymeric concrete with synthetic fiber reinforcement against reflective cracking in rigid pavement overlay

    International Nuclear Information System (INIS)

    Cement concrete pavements are used for heavy traffic loads throughout the world owing to its better and economical performance. Placing of a concrete overlay on the existing pavement is the most prevalent rehabilitating method for such pavements, however, the problem associated with the newly placed overlay is the occurrence of reflective cracking. This paper presents an assessment of the performance of polymeric concrete with synthetic fiber reinforcement against reflective cracking in an overlay system. The performance of polymeric concrete with synthetic fibers as an overlay material is measured in terms of the load-deflection, strain-deflection and load-strain behavior of beams of the polymeric concrete. For this purpose, five types of beams having different number of fiber wires and position are tested for flexure strength. Deflection/strains for each increment of load are recorded. In addition, cubes of plain concrete and of concrete with synthetic fiber needles were tested after 7 and 28 days for compressive strengths. Finite element models in ANSYS software for the beams have also been developed. Beams with greater number of longitudinal fiber wires displayed relatively better performance against deflection whilst beams with synthetic fiber needles showed better performance against strains. Thus, polymeric concrete overlay with fiber reinforcement will serve relatively better against occurrence of reflective cracking. (author)

  14. Chloride Transport in Undersea Concrete Tunnel

    Directory of Open Access Journals (Sweden)

    Yuanzhu Zhang

    2016-01-01

    Full Text Available Based on water penetration in unsaturated concrete of underwater tunnel, a diffusion-advection theoretical model of chloride in undersea concrete tunnel was proposed. The basic parameters including porosity, saturated hydraulic conductivity, chloride diffusion coefficient, initial water saturation, and moisture retention function of concrete specimens with two water-binder ratios were determined through lab-scale experiments. The variation of chloride concentration with pressuring time, location, solution concentration, initial saturation, hydraulic pressure, and water-binder ratio was investigated through chloride transport tests under external water pressure. In addition, the change and distribution of chloride concentration of isothermal horizontal flow were numerically analyzed using TOUGH2 software. The results show that chloride transport in unsaturated concrete under external water pressure is a combined effect of diffusion and advection instead of diffusion. Chloride concentration increased with increasing solution concentration for diffusion and increased with an increase in water pressure and a decrease in initial saturation for advection. The dominant driving force converted with time and saturation. When predicting the service life of undersea concrete tunnel, it is suggested that advection is taken into consideration; otherwise the durability tends to be unsafe.

  15. Infant Perception of Incongruent Shapes in Cast Shadows

    Directory of Open Access Journals (Sweden)

    Kazuki Sato

    2015-04-01

    Full Text Available A cast shadow occurs when an object blocks the light from an illumination and projects a dark region onto a surface. Previous studies have reported that adults are slower to identify an object when the object has an incongruent cast shadow than when it has a congruent cast shadow (Castiello, 2001. Here, we used the familiarization-novelty preference procedure to examine whether 5- to 8-month-old infants could detect the relationship between object shapes and cast shadows. In Experiment 1, we examined the infants' ability to detect incongruency between objects and cast shadows. Results showed that 7- to 8-month olds could detect incongruence between the object shapes and the cast shadows, whereas 5- to 6-month olds did not. Yet, our control experiment showed that infants could not detect this incongruence from stimuli in which a white outline had been added to the original cast shadow to decrease the possibility of it being perceived as a cast shadow (Experiment 2. The results of these experiments demonstrate that 7- to 8-month olds responded to the congruence of cast shadows and to consistent contrast polarity between the cast shadow and its background.

  16. Foundry Wastes Reuse and Recycling in Concrete Production

    Directory of Open Access Journals (Sweden)

    Silvia Fiore

    2007-01-01

    Full Text Available The industrial process of a cast iron foundry plant located in the North of Italy was analyzed in order to determine the amount and kind of produced wastes. The main fractions are core and moulding sands, muds and powders from dust abatement plants, furnace and ladle slags, and exhaust lime, making about 750-800 t/d of residues for a production of about 800 t/d of globular and grey cast iron. All wastes were sampled and characterized by means of particle-size distribution and chemical analyses to evaluate the best reuse and recycling solutions. On the grounds of the gathered results, the residues may be divided in three categories according to the particle-size dimensions: below 0.1 mm, between 0.1 and 0.6 mm and above 0.6 mm. The fraction above 0.6 mm, mainly made of metallic iron, may be reused in the furnaces. The fraction between 0.1 mm and 0.6 mm may be reused in cores production, after a regeneration treatment. The fraction between 0.1 and 0.025 mm may be recycled as raw material for the concrete industry, and the below 0.025 mm fraction may be reused in green moulding operations. An economic evaluation of the proposed reuse and recycling solutions was performed.

  17. Continuous analysis of cast-in-olace concrete voided flat floor%现浇混凝土圆管式空心楼板的连续化分析

    Institute of Scientific and Technical Information of China (English)

    张荣兰

    2011-01-01

    Continuous models basic supposition voided slab floor about bring forward, based on the summarizing of theories and methods of voided flat floor, studied on the designing calculation of structure system, by means of combining continuous analyses and calculations of multiform models of finite element. Formula of vertical deflection and global equivalent flexural rigidity of cross voided slab is inferred under two ends supported in the same direction as the hollow,which is one of important conditions for ends supported.%采用连续化分析法与有限元模型计算相结合的研究手段,提出了圆管式空心板连续化模型的基本假定;推导了顺管向两端支承的圆管式横向空心板在竖向均布荷载下的连续化方程,并对其进行了求解.最后,推导了其整体等效抗弯刚度,为四边支承圆管式空心楼盖的连续化分析提供了重要的条件.

  18. Comparison of residual stresses in sand- and chill casting of ductile cast iron wind turbine main shafts

    DEFF Research Database (Denmark)

    Sonne, Mads Rostgaard; Frandsen, J. O.; Hattel, Jesper Henri

    2015-01-01

    In this work, simulations of pouring, solidification and cooling, and residual stress evolution of sand and chill cast wind turbine main shafts is performed. The models are made in the commercial software MAGMAsoft. As expected, the cooling rate of the sand casting is shown to be much lower than...... for the chill casting, resulting in a very course microstructure.From the simulations the nodule count is found to be 17 nodules per mm2 and 159 nodules permm2 for the sand and chill casting, respectively, in the critical region of the main bearing seat.This is verified from nodule counts performed on...... the real cast main shafts. Residual stressevaluations show an overall increase of the maximum principal stress field for the chill casting,which is expected. However, the stresses are found to be in compression on the surface of thechill cast main shaft, which is unforeseen....

  19. The history and present of art casting in China

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    @@ A compendiary review of art casting in China: History of art casting in china has been over 5000 years. In the past few thousand years, numerous forming and decorating skills of art castings had been created, and left behind precious treasures in the world metal arts and crafts. In individual historical period and at different terrain, a unique artistic style formed,which flashed brilliant light in world artistic treasury.

  20. CENTRIFUGAL CASTING MACHINE

    Science.gov (United States)

    Shuck, A.B.

    1958-04-01

    A device is described that is specifically designed to cast uraniumn fuel rods in a vacuunn, in order to obtain flawless, nonoxidized castings which subsequently require a maximum of machining or wastage of the expensive processed material. A chamber surrounded with heating elements is connected to the molds, and the entire apparatus is housed in an airtight container. A charge of uranium is placed in the chamber, heated, then is allowed to flow into the molds While being rotated. Water circulating through passages in the molds chills the casting to form a fine grained fuel rod in nearly finished form.

  1. Effect of casting/mould interfacial heat transfer during solidification of aluminium alloys cast in CO2-sand mould

    Science.gov (United States)

    Kulkarni, S. N.; Radhakrishna, D. K.

    2011-06-01

    The ability of heat to flow across the casting and through the interface from the casting to the mold directly affects the evolution of solidification and plays a notable role in determining the freezing conditions within the casting, mainly in foundry systems of high thermal diffusivity such as chill castings. An experimental procedure has been utilized to measure the formation process of an interfacial gap and metal-mould interfacial movement during solidification of hollow cylindrical castings of Al-4.5 % Cu alloy cast in CO2-sand mould. Heat flow between the casting and the mould during solidification of Al-4.5 % Cu alloy in CO2-sand mould was assessed using an inverse modeling technique. The analysis yielded the interfacial heat flux ( q), heat transfer coefficient ( h) and the surface temperatures of the casting and the mould during solidification of the casting. The peak heat flux was incorporated as a dimensionless number and modeled as a function of the thermal diffusivities of the casting and the mould materials. Heat flux transients were normalized with respect to the peak heat flux and modeled as a function of time. The heat flux model proposed was to estimate the heat flux transients during solidification of Al-4.5 % Cu alloy cast in CO2-sand moulds.

  2. Durability of Steel Fibres Reinforcement Concrete Beams in Chloride Environment Combined with Inhibitor

    Directory of Open Access Journals (Sweden)

    AbdelMonem Masmoudi

    2016-01-01

    Full Text Available This paper presented the effect of the combination of an inhibitor and steel fibre reinforced concrete (SFRC for concrete structures in chloride environments. Twelve beams were cast and tested to study their flexural behavior. The morphology of steel surfaces using the inhibitor after observing the scanning electron microscope showed a low layer of corrosion products. The steel surface immersed in the inhibitor free solution was seen to have been subject to chloride ions attacks as shown in this study. The interest to the field of the present study is the relatively higher durability of the performance when using the inhibitor. Crack width and crack spacing for beams under the same load showed that the use of SFRC with the inhibitor for concrete structures in chloride environments must have transferred tension across cracks that led to reducing crack spacing without any chloride ions attack.

  3. Dynamic control of crystallinity in polymer film casting process

    OpenAIRE

    Thananchai Leephakpreeda

    2005-01-01

    This paper presents an approach for dynamic control of crystallinity in polymer film casting process. As known, the transients of crystallization dictate the microstructures of semi-crystalline polymer during solidification. In turn, the properties of finished products can be determined by adjustable variables in polymer film casting process such as temperature of chill roll. In this work, an experimental model of the solidification in film casting process is derived by a system identificatio...

  4. Low Background Micromegas in CAST

    DEFF Research Database (Denmark)

    Garza, J G; Aune, S.; Aznar, F.;

    2014-01-01

    to background levels below 10−6 counts/keV/cm2/s, more than a factor 100 lower than the first generation of Micromegas detectors. The best levels achieved at the Canfranc Underground Laboratory (LSC) are as low as 10−7 counts/keV/cm2/s, showing good prospects for the application of this technology in IAXO...

  5. Graphitization in chromium cast iron

    OpenAIRE

    LECOMTE-BECKERS, Jacqueline; Terziev, L.; Breyer, J. P.

    1998-01-01

    Some trials with graphite Hi-Cr iron rolls have been done mainly in Japan, for the rolling of stainless steel. This material could lead to good compromise between oxidation, wear and thermal behaviour. By using thermal analysis and resistometry, the conditions for secondary graphite formation have been studied. The amount and volume of free graphite may be strongly increased by a suitable heat treatment, allowing a good thermal conductivity as well as high wear and mechanical properties.

  6. BETWEEN THE DENDRITE STRUCTURE QUALITY, THE CASTING TECHNOLOGY AND THE DEFECTS IN CONTINUOUSLY CAST SLABS

    Directory of Open Access Journals (Sweden)

    Slavomír Peľák

    2009-11-01

    Full Text Available The paper presents the results of analysis of surface defects of continuously cast slabs. Longitudinal central cracks of type II, accompanied by local depression, were found. The local depressions were formed in areas with the thinnest slab chill zone. We suppose that they were caused by heterogeneous contraction of solidified shell. The second part of the paper analyzes the relationships between the chemical composition, the dendrite structure parameters, the casting technology parameters and the occurrence of defects in continuously cast slabs. To determine the susceptibility of the steel to longitudinal cracking, we analyzed the relationships between a large variety of data (slab chemical composition, casting speed, casting and overheating temperatures, primary and secondary dendrite arm spacing, etc.. The longitudinal defects were more frequent in overheated steel, with a small central zone, great dendrite arm spacing and with a higher than recommended sulphur and phosphorus content. Numerically expressed, cracking developed at the segregation index values IS bigger/same 100, with the surface cracking index IPT bigger/same 60.

  7. Modeling of fiber orientation in viscous fluid flow with application to self-compacting concrete

    Science.gov (United States)

    Kolařík, Filip; Patzák, Bořek

    2013-10-01

    In recent years, unconventional concrete reinforcement is of growing popularity. Especially fiber reinforcement has very wide usage in high performance concretes like "Self Compacting Concrete" (SCC). The design of advanced tailor-made structures made of SCC can take advantage of anisotropic orientation of fibers. Tools for fiber orientation predictions can contribute to design of tailor made structure and allow to develop casting procedures that enable to achieve the desired fiber distribution and orientation. This paper deals with development and implementation of suitable tool for prediction of fiber orientation in a fluid based on the knowledge of the velocity field. Statistical approach to the topic is employed. Fiber orientation is described by a probability distribution of the fiber angle.

  8. Analyses of concrete microcosmic structure in multi-media environment

    Institute of Scientific and Technical Information of China (English)

    闫波; 姜安玺; 王幼青; 刘丽艳; 徐桂芹

    2004-01-01

    The structure of concrete generally serves in multi-media environments; various environments act differently on concrete. The compound action of some severe environments will threaten the duration of concrete and decrease the service life of a concrete structure if improperly handled. In this paper the microstructure of concrete is observed by using Scanned Electric Microscope (SEM) through contrasting experiments in media of acid, alkali and salt with that of freezing-thawing in the same medium environment. This study is to supply a certain basis for changing traditional thinking of mechanical design and to combine construction reliability design with durability of concrete design.

  9. Phase Transformations in Cast Duplex Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Yoon-Jun Kim

    2004-12-19

    Duplex stainless steels (DSS) constitute both ferrite and austenite as a matrix. Such a microstructure confers a high corrosion resistance with favorable mechanical properties. However, intermetallic phases such as {sigma} and {chi} can also form during casting or high-temperature processing and can degrade the properties of the DSS. This research was initiated to develop time-temperature-transformation (TTT) and continuous-cooling-transformation (CCT) diagrams of two types of cast duplex stainless steels, CD3MN (Fe-22Cr-5Ni-Mo-N) and CD3MWCuN (Fe-25Cr-7Ni-Mo-W-Cu-N), in order to understand the time and temperature ranges for intermetallic phase formation. The alloys were heat treated isothermally or under controlled cooling conditions and then characterized using conventional metallographic methods that included tint etching, and also using electron microscopy (SEM, TEM) and wavelength dispersive spectroscopy (WDS). The kinetics of intermetallic-phase ({sigma} + {chi}) formation were analyzed using the Johnson-Mehl-Avrami (MA) equation in the case of isothermal transformations and a modified form of this equation in the case of continuous cooling transformations. The rate of intermetallic-phase formation was found to be much faster in CD3MWCuN than CD3MN due mainly to differences in the major alloying contents such as Cr, Ni and Mo. To examine in more detail the effects of these elements of the phase stabilities; a series of eight steel castings was designed with the Cr, Ni and Mo contents systematically varied with respect to the nominal composition of CD3MN. The effects of varying the contents of alloying additions on the formation of intermetallic phases were also studied computationally using the commercial thermodynamic software package, Thermo-Calc. In general, {sigma} was stabilized with increasing Cr addition and {chi} by increasing Mo addition. However, a delicate balance among Ni and other minor elements such as N and Si also exists. Phase equilibria in

  10. Phase transformations in cast duplex stainless steels

    Science.gov (United States)

    Kim, Yoon-Jun

    Duplex stainless steels (DSS) constitute both ferrite and austenite as a matrix. Such a microstructure confers a high corrosion resistance with favorable mechanical properties. However, intermetallic phases such as sigma (sigma) and chi (chi) can also form during casting or high-temperature processing and can degrade the properties of the DSS. This research was initiated to develop time-temperature-transformation (TTT) and continuous-cooling-transformation (CCT) diagrams of two types of cast duplex stainless steels, CD3MN (Fe-22Cr-5Ni-Mo-N) and CD3MWCuN (Fe-25Cr-7Ni-Mo-W-Cu-N), in order to understand the time and temperature ranges for intermetallic phase formation. The alloys were heat treated isothermally or under controlled cooling conditions and then characterized using conventional metallographic methods that included tint etching, and also using electron microscopy (SEM, TEM) and wavelength dispersive spectroscopy (WDS). The kinetics of intermetallic-phase (sigma + chi) formation were analyzed using the Johnson-Mehl-Avrami (JMA) equation in the case of isothermal transformations and a modified form of this equation in the case of continuous cooling transformations. The rate of intermetallic-phase formation was found to be much faster in CD3MWCuN than CD3MN due mainly to differences in the major alloying contents such as Cr, Ni and Mo. To examine in more detail the effects of these elements of the phase stabilities, a series of eight steel castings was designed with the Cr, Ni and Mo contents systematically varied with respect to the nominal composition of CD3MN. The effects of varying the contents of alloying additions on the formation of intermetallic phases were also studied computationally using the commercial thermodynamic software package, Thermo-Calc. In general, a was stabilized with increasing Cr addition and chi by increasing Mo addition. However, a delicate balance among Ni and other minor elements such as N and Si also exists. Phase equilibria in

  11. Examples of material solutions in bimetallic layered castings

    Directory of Open Access Journals (Sweden)

    S. Tenerowicz

    2011-07-01

    Full Text Available In paper is presented technology of bimetallic layered castings based on founding method of layer coating directly in cast process so-called method of mould cavity preparation. Prepared castings consist two fundamental parts i.e. bearing part and working part (layer. The bearing part of bimetallic layered casting is typical foundry material i.e. pearlitic grey cast iron, whereas working part (layer is depending on accepted variant plates of alloy steels sort X6Cr13, X12Cr13, X10CrNi18-8 and X2CrNiMoN22-5-3. The ratio of thickness between bearing and working part is 8:1. The verification of the bimetallic layered castings was evaluated on the basis of ultrasonic NDT (non-destructive testing, structure and macro- and microhardness researches.

  12. Caste Discrimination, Land Reforms and Land Market Performance in Nepal

    OpenAIRE

    Aryal, Jeetendra P.; Holden, Stein T.

    2011-01-01

    This paper assesses the implications of caste discrimination and past land reforms on the land rental market performance, land productivity and land use intensity in Nepal. The most severely discriminated group in the caste system is the Dalits, the so-called “untouchables”. Dalits faced religious, occupational and even, territorial discrimination. The study uses data from western Nepal. The low-caste households remain poorer than other households, have significantly smaller land endowments, ...

  13. The Effects of Drainer Formworks With Sucker Lining on The Concrete Surface Properties

    OpenAIRE

    ARSLAN, Metin

    1999-01-01

    In this research, the alternative formworks which are without lining and which are with sucker lining-drainer are produced. On the concrete blocks which are casted in formworks; blowhole on the surface, surface hardness with schmidth hammer, pull-out resistance, capilları absorption, sodium-sulfate frost resistance, abrasion resistance experiments are made. As a result; the concretes which are casted on sucker lining and drainaged formworks has better concrete surface properties than...

  14. Cracking control in mass concrete for three gorges dam; Sankyo damu ni okeru masu konkurito no hibiware yokusei

    Energy Technology Data Exchange (ETDEWEB)

    Chu, CHuanying

    1999-09-10

    The provisional cofferdam work of the mainstream of Three Gorges Dam project was successfully finished on November 8, 1997. Now, the work enters its second stage, and the placing of large-scale concrete was started. The total quantity of concrete used in this project reaches 15.00 million m{sup 3}. Inhibition of dam concrete cracking is an important subject. In order to manufacture concrete with good crack-resistance, cements, fly ashes, aggregates and blending agents are strictly selected; and hydration-generating heat is reduced by means of strict temperature control, precooling of aggregates, reduction of placing temperature and concrete temperature in mixers, and the like. As a consequence of maintaining the highest temperature value in concrete blocks to be lower than a predetermined value, harmful cracks can be prevented from occurring when the temperature in the dam lowers. (NEDO)

  15. Prompt gamma-ray analysis of chlorine in superpozz cement concrete

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A., E-mail: aanaqvi@kfupm.edu.sa [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Kalakada, Zameer [Department of Civil Engineering, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Al-Matouq, Faris A. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Maslehuddin, M. [Center for Engineering Research, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Al-Amoudi, O.S.B. [Department of Civil Engineering, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Ur-Rehman, Khateeb [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia)

    2012-11-21

    The chlorine concentration in Superpozz (SPZ) cement concrete was analyzed using a newly designed prompt gamma-ray neutron activation (PGNAA) setup utilizing a portable neutron generator. The setup, which mainly consists of a neutron source along with its moderator placed side by side with a shielded gamma-ray detector, allows determining chloride concentration in a concrete structure from one side. The setup has been tested through chlorine detection in chloride-contaminated Superpozz (SPZ) cement concrete specimens using 6.11 and 2.86{+-}3.10 MeV chlorine prompt gamma-rays. The optimum 0.032{+-}0.012 wt% value of Minimum Detectable Concentration (MDC) of chlorine in SPZ cement concrete measured in this study shows a successful application of a portable neutron generator in chloride analysis of concrete structure for corrosion studies.

  16. HTGR Base Technology Program. Task 2: concrete properties in nuclear environment. A review of concrete material systems for application to prestressed concrete pressure vessels

    International Nuclear Information System (INIS)

    Prestressed concrete pressure vessels (PCPVs) are designed to serve as primary pressure containment structures. The safety of these structures depends on a correct assessment of the loadings and proper design of the vessels to accept these loadings. Proper vessel design requires a knowledge of the component (material) properties. Because concrete is one of the primary constituents of PCPVs, knowledge of its behavior is required to produce optimum PCPV designs. Concrete material systems are reviewed with respect to constituents, mix design, placing, curing, and strength evaluations, and typical concrete property data are presented. Effects of extreme loadings (elevated temperature, multiaxial, irradiation) on concrete behavior are described. Finally, specialty concrete material systems (high strength, fibrous, polymer, lightweight, refractory) are reviewed. 235 references

  17. HTGR Base Technology Program. Task 2: concrete properties in nuclear environment. A review of concrete material systems for application to prestressed concrete pressure vessels

    Energy Technology Data Exchange (ETDEWEB)

    Naus, D.J.

    1981-05-01

    Prestressed concrete pressure vessels (PCPVs) are designed to serve as primary pressure containment structures. The safety of these structures depends on a correct assessment of the loadings and proper design of the vessels to accept these loadings. Proper vessel design requires a knowledge of the component (material) properties. Because concrete is one of the primary constituents of PCPVs, knowledge of its behavior is required to produce optimum PCPV designs. Concrete material systems are reviewed with respect to constituents, mix design, placing, curing, and strength evaluations, and typical concrete property data are presented. Effects of extreme loadings (elevated temperature, multiaxial, irradiation) on concrete behavior are described. Finally, specialty concrete material systems (high strength, fibrous, polymer, lightweight, refractory) are reviewed. 235 references.

  18. 部分预制装配混凝土结构海洋码头工程设计%Design of Precast and Cast-in-place Concrete Docking Structure in the Texaco Whart Maritime Port

    Institute of Scientific and Technical Information of China (English)

    李镇强; Rigoberto Ramirez C.

    2003-01-01

    在1940年代,美国德克札高(TEXACO)石油公司在洪都拉斯国北方海岸建有一个钢结构的原油码头.1998年德克札高公司在原来的旧址重建新码头和岸边的引桥.新原油码头工程采用预制预应力混凝土桩基础.上部结构采用预制和现浇混凝土叠合结构.施工中基本免除了现场的模板工程作业,大大提高了工程质量,缩短了施工周期.介绍这一设计的特色及施工和安装中的要点,其创新设计观念给码头工程和海工结构的传统设计提供了新的思路.

  19. 混凝土柱后接梁接头抗剪承载力研究%Study on Shear Capacity of Connections of Post-cast Beams Connected with Concrete Columns

    Institute of Scientific and Technical Information of China (English)

    王俊杰; 李志国; 王存贵; 王敏杰; 张磊

    2012-01-01

    Based on the experiment* on two kinds of beam-column joint, the roughened interface with inserting shear reinforcement and the rejected concrete cover with inserting shear reinforcement, the shear performance of the interface of post-cast beams, and the effects of shear reinforcement on the shear performance of connections are discussed. It was showed that the both connections had good performance, their shear capability was up to the level of integral casting beams, and the shear reinforcement could improve the shear capacity of the interface between the post-cast beam and the column. The relative slippage between the post-cast beam and the column in the roughened interface joint was less than in the rejected concrete cover joint. This paper discusses the shear performance and the mechanism of two joint forms, and sets up the calculation methods of the shear capacity, the proposal formulas agree with the results of the experiments well, so they could be used as a reference for the engineering design.%通过对无齿直缝植抗剪筋、剔凿混凝土保护层植抗剪筋两种柱后接梁接头形式的试验研究,讨论后接梁柱界面的抗剪性能,以及抗剪筋对接头抗剪性能的影响.试验结果证实:这两种接头形式都具有较好的抗剪能力,其受剪承载力均可以达到整浇式的水平,且植入抗剪筋有利于提高后接梁柱界面的受剪承载力,无齿直缝接头形式梁柱界面相对滑移小于剔凿混凝土保护层的接头形式.本文讨论了此两种接头形式的抗剪性能及机理,并建立了受剪承载力的验算方法,所提建议公式与实验结果相吻合,可供工程设计参考.

  20. Thin wall ductile iron casting as a substitute for aluminum alloy casting in automotive industry

    Directory of Open Access Journals (Sweden)

    M. Górny

    2009-01-01

    Full Text Available In paper it is presented thin wall ductile iron casting (TWDI as a substitute of aluminium alloy casting. Upper control arm made of ductile iron with wall thickness ranging from 2 – 3.7 mm was produced by inmold process. Structure, mechanical properties and computer simulations were investigated. Structural analysis of TWDI shows pearlitic-ferritic matrix free from chills and porosity. Mechanical testing disclose superior ultimate tensile strength (Rm, yield strength (Rp0,2 and slightly lower elongation (E of TWDI in comparison with forged control arm made of aluminium alloy (6061-T6. Moreover results of computer simulation of static loading for tested control arms are presented. Analysis show that the light-weight ductile iron casting can be loaded to similar working conditions as the forged Al alloy without any potential failures.

  1. In Search of Place Brand Identity

    DEFF Research Database (Denmark)

    Kvistgaard, Hans-Peter; Blichfeldt, Bodil Stilling; Hird, John

    2015-01-01

    Place branding relates both to brand identity (what the place is) and brand image (what the place is/should be in the eyes of external audiences). Brand identity can be perceived as the set of values and attributes that those responsible for marketing and development of a place wish to reinforce...

  2. Self-compacting concrete and its application in contemporary architectural practice

    OpenAIRE

    Okrajnov-Bajić Ruža; Vasović Dejan

    2009-01-01

    In majority of the most modern architectural designs realized in the past 10-20 years, concrete having features in fresh and hardened state as well as making, placing and curing techniques that are defined in detail was used. Quite frequently concrete which was self-compacting in fresh state was used. In order to get acquainted with this material and with possibilities of its application this paper presents various buildings in which it was used. The definition of self-compacting concre...

  3. Numerical Simulation System for Casting Process in Concurrent Engineering

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    According to the implementing principle and application background of the Concurrent Engineering (CE) project, studies on the integration of numerical simulation system for casting process with CE, simulation of turbulent phenomena in filling process of casting by Algebraic Stress Model (ASM), computation efficiency of filling process and quantitative prediction of shrinkage cavity and porosity under feeding condition of several risers are discussed. After the simulation of casting process of typical magnesium-based alloy casting with complicated structure, remarkable success in assuring the quality is also presented.

  4. CT measurements of SAP voids in concrete

    DEFF Research Database (Denmark)

    Laustsen, Sara; Bentz, Dale P.; Hasholt, Marianne Tange;

    2010-01-01

    X-ray computed tomography (CT) scanning is used to determine the SAP void distribution in hardened concrete. Three different approaches are used to analyse a binary data set created from CT measurement. One approach classifies a cluster of connected, empty voxels (volumetric pixel of a 3D image......) as one void, whereas the other two approaches are able to classify a cluster of connected, empty voxels as a number of individual voids. Superabsorbent polymers (SAP) have been used to incorporate air into concrete. An advantage of using SAP is that it enables control of the amount and size...

  5. Casting granular ion exchange resins with medium-active waste in cement

    International Nuclear Information System (INIS)

    Medium active waste from nuclear power stations in Sweden is trapped in granular ion exchange resins. The resin is mixed with cement paste and cast in a concrete shell which is cubic and has an edge dimension of 1.2 m. In some cases the ion exchange cement mortar has cracked. The report presents laboratory sutdies of the properties of the ion exchange resin and the mortar. Also the leaching of the moulds has been investigated. It was shown that a mixture with a water cement ratio higher than about 0.5 swells considerably during the first weeks after casting. The diffusion constant for cesium 137 has been determined at 3.10-4 cm2/24-hour period in conjunction with exposure of the mould and mortar to sea water. The Swedish language report has 400 pages with 90 figures and 30 tables. (author)

  6. Development,Application and Problem of Ductile Iron Lost Foam Casting Technology in China

    Institute of Scientific and Technical Information of China (English)

    He Wenhao; Ye Shengping; Han Xiaohong; Tang Suoyun

    2010-01-01

    @@ Lost-foam casting is a 21st century green casting technology.Over the past decade,there has been an extraordinary development in lost-foam casting in China;and ductile iron lost-foam casting has developed even more rapidly in foundry equipment,foundry raw materials,and casting engineers.

  7. A STDY ON EFFECT OF SIZE OF AGGREGATE ON COMPRESSIVE STRENGHT OF CONCRETE AND STRENGHT CHARACTERSTICS BY UTILIZATIION OF WASTE MATERIALS AS COURSE AGGREGATE IN CONCRETE

    Directory of Open Access Journals (Sweden)

    SETTIUBATHULA RAMYA

    2015-05-01

    Full Text Available Depletion of natural resources is a common phenomenon in developing countries like India due to rapid urbanization and Industrialization involving construction of Infrastructure and other amenities. In view of this, searching for suitable other viable alternative materials for concrete so that the existing natural resources could be preserved to the possible extent, for the future generation. To investigate the effect of size of aggregate on the compressive strength of concrete an experimental program was carried out. Four different sizes of coarse aggregates were used while developing the mix design. The sizes of coarse aggregate were 25mm, 20mm, 10mm and 4.75mm. Natural sand with fineness modules of 3.48 was used as fine aggregate. Ordinary Portland cement of 43 Grade was used as binding material. Different trials of mixing of coarse aggregate were made (25 mm and 20mm, 20mm and 10mm, 10mm and 4.75mm to investigate the influence of size of aggregate on compressive strength of concrete. Cubes of size 150mmx150mmx150mm were cast in laboratory and tested in Compression Testing Machine. It was concluded that 10mm and 4.75mm aggregates showed higher compressive strength than other types of aggregates. The tests revealed that on the replacement of 20% of ceramic tiles had increased the compressive strength of 13% more than that of conventional concrete. And it was observed that optimum ceramic tiles content was 20%. It is observed that by using 10% of plastic waste in concrete ,the fatigue characteristics of modified concrete has increased than that of plain cement concrete

  8. Field Testing of Rapid Electrokinetic Nanoparticle Treatment for Corrosion Control of Steel in Concrete

    Science.gov (United States)

    Cardenas, Henry E.; Alexander, Joshua B.; Kupwade-Patil,Kunal; Calle, Luz Marina

    2009-01-01

    This work field tested the use of electrokinetics for delivery of concrete sealing nanoparticles concurrent with the extraction of chlorides. Several cylinders of concrete were batched and placed in immersion at the Kennedy Space Center Beach Corrosion Test Site. The specimens were batched with steel reinforcement and a 4.5 wt.% (weight percent) content of sodium chloride. Upon arrival at Kennedy Space Center, the specimens were placed in the saltwater immersion pool at the Beach Corrosion Test Site. Following 30 days of saltwater exposure, the specimens were subjected to rapid chloride extraction concurrent with electrokinetic nanoparticle treatment. The treatments were operated at up to eight times the typical current density in order to complete the treatment in 7 days. The findings indicated that the short-term corrosion resistance of the concrete specimens was significantly enhanced as was the strength of the concrete.

  9. Commentary: the place of performative writing in forensic psychiatry.

    Science.gov (United States)

    Griffith, Ezra E H; Baranoski, Madelon V

    2007-01-01

    In this issue of the Journal, Robert Simon has explored the subject of the place that writing should occupy in the professional life of forensic psychiatrists. We have taken the platform so elegantly constructed by this erudite and prolific author and used it to discuss the quotidian and concrete task of writing the customary forensic psychiatry report. We look to other disciplines for mechanisms to analyze the written forensic report: concepts of voice, portraiture, and narrative. We ultimately conclude that preparing these reports is a complex undertaking and that writing with clarity, precision, and artistry in forensic psychiatry should be viewed as a core competency. PMID:17389341

  10. 浅谈混凝土现浇板裂缝的认识和防治措施%Discussion on the understanding and prevention measures of concrete cast-in-place floor crack

    Institute of Scientific and Technical Information of China (English)

    薛广玉

    2008-01-01

    针对混凝土现浇板裂缝的危害性,对住宅楼现浇板裂缝的产生原因做了具体的分析,说明了现浇板开裂容易出现的部位和常出现裂缝的形状,针对不同形式的裂缝提出了相应的预防及处理措施.

  11. 现浇框架模板预装及梁的钢筋整体入模施工%Pre-installation of cast-in-place frame formwork and reinforcement integral construction of beam before concrete pouring

    Institute of Scientific and Technical Information of China (English)

    臧俊林; 任旭亮

    2003-01-01

    针对某现浇框架的施工,由于工期比较紧,常规施工无法完成的情况,阐述了采用模板预装及梁的钢筋整体入模的施工方法,减少了因交叉施工占用的工期.强调了在施工时应注意安排好现场的施工顺序.

  12. Experimental validation of error in temperature measurements in thin walled ductile iron castings

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2007-01-01

    thicknesses between 2 and 4.3 mm. The thermocouples were accurately placed at the same distance from the surface of the casting for different plate thicknesses. It is shown that when measuring the temperature in plates with thickness between 2 and 4.3 mm the measured temperature will be parallel shifted to a...... level about 20C lower than the actual temperature in the casting. Factors affecting the measurement error (oxide layer on the thermocouple wire, penetration into the ceramic tube and variation in placement of thermocouple) are discussed. Finally, it is shown how useful cooling curve may be obtained in...

  13. Waste polyethylene terephthalate as an aggregate in concrete

    Directory of Open Access Journals (Sweden)

    Nabajyoti Saikia

    2013-04-01

    Full Text Available This paper reports the strength behaviour of concrete containing three types of recycled polyethylene terephthalate (PET aggregate. Results are also analysed to determine the PET-aggregate's effect on the relationship between the flexural and splitting tensile strengths and compressive strength and to know whether the relationships between compressive strength and other strength characteristics given in European design codes are applicable to concrete made with PET-aggregates. The compressive strength development of concrete containing all types of PET-aggregate behaves like in conventional concrete, though the incorporation of any type of PET-aggregate significantly lowers the compressive strength of the resulting concrete. The PET-aggregate incorporation improves the toughness behaviour of the resulting concrete. This behaviour is dependent on PET-aggregate's shape and is maximised for concrete containing coarse, flaky PET-aggregate. The splitting tensile and flexural strength characteristics are proportional to the loss in compressive strength of concrete containing plastic aggregates.

  14. Effects of Aspect Ratio on the Observed Hoop Strain Variation in FRP Confined Concrete Cylinders

    OpenAIRE

    Bisby, L. A.; Sinclair, D; Webster, M.; Stratford, T. J.; Take, W.A.

    2009-01-01

    Confinement of circular concrete columns by circumferential fibre reinforced polymer (FRP) wraps is among the most widely implemented applications of FRP materials for infrastructure. FRPs are wrapped in the hoop direction around the perimeter of concrete columns and bonded in place with an epoxy adhesive; the effect of this is to drastically improve the columns’ strength and deformability, which has clear benefits for axial strengthening, seismic enhancement, and blast damage mitigation. The...

  15. Performance of concrete backfilling materials for shafts and tunnels in rock formations. Volume 1: concrete selection and properties

    International Nuclear Information System (INIS)

    Preplaced Aggregate Concrete (PAC) consists of graded coarse aggregate, immobilised by cementitious grout injected into the voids. PAC can be considered as a suitable backfill material for mined radioactive waste repositories. PAC is also reported to be amenable to mechanical/remote placement and have usefully improved properties when compared with conventionally placed concretes. In particular reduced shrinkage and heat cycle during cement hydration, higher densities and improved plant economics are claimed. This study attempts to establish the validity of these claims both from reported experience and by practical demonstration through experimentation. A literature study supported the claims made for the PAC system but all reported experiences recorded the use of organic admixtures (workability aids, retarders etc). Because of the lack of long term durability data on such admixtures, especially in a radiation environnement, it was decided to prepare a sample of PAC without organic admixtures. Considerable experimental difficulties were encountered in obtaining a satisfactory quality for test specimens. The necessary grout fluidity was only achieved by the inclusion of bentonite. The test data collected indicates that the PAC system employed did not improve mechanical properties compared with conventional concretes. This is attributed to the non-usage of organic admixtures to achieve the expected performance. Further research on low permeability concretes would require the use of organic admixtures. The effect of radiation on these materials, and their leaching rate needs to be quantified

  16. Prestress losses evaluation in prestressed concrete prismatic specimens

    OpenAIRE

    CARO FORERO, LIBARDO ANDRÉS; Martí Vargas, José Rocío; Serna Ros, Pedro

    2013-01-01

    This paper presents an experimental research work to evaluate prestress losses in pretensioned prestressed concrete. An experimental program including variables such as concrete mix design, specimen cross-section size and concrete age at the prestress transfer was carried out. Several pretensioned prestressed concrete prismatic specimens were made and tested using the ECADA+ test method, based on measuring prestressing reinforcement force. In addition, specimens were instrumented to obtain th...

  17. Concrete with superabsorbent polymers (SAP) - experience from the Fehmarn field exposure station in Rødbyhavn

    DEFF Research Database (Denmark)

    Hasholt, Marianne Tange; Pade, Claus

    2011-01-01

    A field exposure station has been established in Rødbyhavn Habour. One of the concrete types tested is with superabsorbent polymer (SAP) - a new type of additive, which can be used to mitigate self-desiccation and to control air void structure. This paper presents results from the extensive...... laboratory test program, which was conducted before test panels were placed in Rødbyhavn Habour. Results show that when using SAP, it is possible to produce concrete with a pre-defined air void structure. Strength and transport properties are comparable to the properties of a reference concrete, but results...

  18. Asphalt Pavement Concrete Stable Cold In-place Recycling Construction Technology%浅述沥青路面水泥稳定就地冷再生施工工艺

    Institute of Scientific and Technical Information of China (English)

    侯睿妮

    2013-01-01

    本文论述了水泥稳定碎石就地冷再生施工工艺在大修工程中的应用,介绍施工特点、施工工艺及对效益进行分析.%The paper discusses the application of cement stable macadam cold regeneration in situ construction technology in overhaul engineering, and presents construction features, construction technology, and benefit.

  19. Effective Utilisation of Waste Glass in Concrete

    Directory of Open Access Journals (Sweden)

    Sameer Shaikh

    2015-12-01

    Full Text Available Glass is a widely used product throughout the world; it is versatile, durable and reliable. The uses of glass ranges drastically, therefore waste glass is discarded, stockpiled or land filled. About million tons of waste glass is generated and around large percent of this glass is disposed of in landfills. This pattern has influenced environmental organizations to pressure the professional community to lower the amount of glass being discarded as well as find use to the non-recycled glass in new applications. In relation, the recycling of waste glass as a component in concrete gives waste glass a sustainable alternative to land filling and therefore makes it economically viable.The proposed study of utilising waste glass powder(GLP in concrete as partial replacement of cement as well as the use of crushed glass particles(CGP retained on 1.18mm & 2.36mm IS sieve as a partial replacement to sand, which offers important benefits related to strength of concrete as well as it is eco-friendly. Recycling of mixed-colour waste glass possesses major problems for municipalities, and this problem can be greatly eliminated by re-using waste glass as sand/cement replacement in concrete. Moreover, re-using waste materials in construction can reduce the demand on the sources of primary materials.In this project the attempts have been made to partially replace the cement as well as sand by waste glass powder and crushed glass particles with equal combination by 5% interval up to 20% replacement and observe its effect on the strength of concrete after 7 days and 28 days of curing.

  20. Shear Reinforcements in the Reinforced Concrete Beams

    Directory of Open Access Journals (Sweden)

    Moayyad M. Al-Nasra

    2013-10-01

    Full Text Available - This study focuses on the use of different types of shear reinforcement in the reinforced concrete beams. Four different types of shear reinforcement are investigated; traditional stirrups, welded swimmer bars, bolted swimmer bars, and u-link bolted swimmer bars. Beam shear strength as well as beam deflection are the main two factors considered in this study. Shear failure in reinforced concrete beams is one of the most undesirable modes of failure due to its rapid progression. This sudden type of failure made it necessary to explore more effective ways to design these beams for shear. The reinforced concrete beams show different behavior at the failure stage in shear compare to the bending, which is considered to be unsafe mode of failure. The diagonal cracks that develop due to excess shear forces are considerably wider than the flexural cracks. The cost and safety of shear reinforcement in reinforced concrete beams led to the study of other alternatives. Swimmer bar system is a new type of shear reinforcement. It is a small inclined bars, with its both ends bent horizontally for a short distance and welded or bolted to both top and bottom flexural steel reinforcement. Regardless of the number of swimmer bars used in each inclined plane, the swimmer bars form plane-crack interceptor system instead of bar-crack interceptor system when stirrups are used. Several reinforced concrete beams were carefully prepared and tested in the lab. The results of these tests will be presented and discussed. The deflection of each beam is also measured at incrementally increased applied load.

  1. Investigation on the Potentials of Cupola Furnace Slag in Concrete

    OpenAIRE

    Stephen Adeyemi Alabi; Joseph O. Afolayan

    2013-01-01

    The compressive strength of the concrete designed using blast cupola furnace slag and granulated cupola slag as a coarse aggregate and partial replacement for cement was investigated. A series of experimental studies were conducted involve concrete production in two stages. The first stage comprised of normal aggregate concrete (NAC) produced with normal aggregates and 100% ordinary Portland cement (OPC). Meanwhile, the second stage involved production of concrete comprising of cupola furnace...

  2. The ancient Chinese casting techniques

    OpenAIRE

    Tan Derui; Lian Haiping

    2011-01-01

    In the course of Chinese civilization, which lasted more than 5,000 years, casting production has made a huge contribution. In this paper, some representative metal castings were presented. According to their forming techniques, they can be grouped into stone mould casting, clay mould casting, ablation casting, lost wax casting, stack casting, permanent mould casting, sand casting, etc. According to their materials, they can be categorized into tin bronze, bimetallic bronze, malleable cast ir...

  3. Probabilistic modeling of solidification grain structure in investment castings

    Energy Technology Data Exchange (ETDEWEB)

    Upadhya, G.K.; Yu, K.O.; Layton, M.A.; Paul, A.J. [Concurrent Technologies Corp., Johnstown, PA (United States)

    1995-12-31

    A probabilistic approach for modeling the evolution of grain structure in investment castings has been developed. The approach differs from the classical Monte Carlo simulations of microstructural evolution in that it uses the results from a heat transfer simulation of the investment casting process for determining the probabilities of nucleation and growth. The model was used to predict the solidification grain structure in castings. The model is quasi-3D, since it uses the information from a 3D simulation of heat transfer to predict the grain structure developed in any 2D-section of the casting. Structural transitions such as columnar/equiaxed transition can also be predicted, using suitable transition criteria. Results from the model have been validated by comparison with actual micrographs from experimental investment castings. In the first case, simulations were performed for a simple plate shaped casting of superalloy Rene 77. The effects of mold insulation as well as metal pour and mold preheat temperatures on the grain size of the casting were studied. In the second example, the casting of a complex-shaped jet engine component made of superalloy IN718 was simulated. Simulation results were seen to match very well with experiments.

  4. Disperse reinforced concrete used in obtaining prefabricated elements for roads

    Directory of Open Access Journals (Sweden)

    Bogdan MEZEI

    2014-07-01

    Full Text Available Concrete is the most used material in construction. By improving the performance of materials and of technologies, concretes with outstanding performances were also developed, in the past two decades. Concrete with dispersed reinforcement represents a new generation of reinforced concrete that combines a good behavior of concrete compressive strength with an increased tensile strength of steel fibers. Using this material, monolithic and prefabricated concrete elements with high mechanical strengths and high durability can be obtained. Technological processes for preparation of concrete with dispersed reinforcement are similar to the conventional methods and do not involve using additional equipment for dosing the dispersed reinforcement. The study aimed the development of road plates made with optimized disperse- reinforced concrete. The first tests were done on plates from the gutter roadway, having a classic reinforcement, using different percentages of fibre reinforcement in the concrete composition, leading to the development of a new optimized economical solution. The results prove the enhanced characteristics of the disperse-reinforced concrete versus conventional concrete, and hence of the developed concrete plates.

  5. Virtual Mold Technique in Thermal Stress Analysis during Casting Process

    Institute of Scientific and Technical Information of China (English)

    Si-Young Kwak; Jae-Wook Baek; Jeong-Ho Nam; Jeong-Kil Choi

    2008-01-01

    It is important to analyse the casting product and the mold at the same time considering thermal contraction of the casting and thermal expansion of the mold. The analysis considering contact of the casting and the mold induces the precise prediction of stress distribution and the defect such as hot tearing. But it is difficult to generate FEM mesh for the interface of the casting and the mold. Moreover the mesh for the mold domain spends lots of computational time and memory for the analysis due to a number of meshes. Consequently we proposed the virtual mold technique which only uses mesh of the casting part for thermal stress analysis in casting process. The spring bar element in virtual mold technique is used to consider the contact of the casting and the mold. In general, a volume of the mold is much bigger than that of casting part, so the proposed technique decreases the number of mesh and saves the computational memory and time greatly. In this study, the proposed technique was verified by the comparison with the traditional contact technique on a specimen. And the proposed technique gave satisfactory results.

  6. Shrinkage stress in concrete under dry-wet cycles: an example with concrete column

    Science.gov (United States)

    Gao, Yuan; Zhang, Jun; Luosun, Yiming

    2014-02-01

    This paper focuses on the simulation of shrinkage stress in concrete structures under dry-wet environments. In the modeling, an integrative model for autogenous and drying shrinkage predictions of concrete under dry-wet cycles is introduced first. Second, a model taking both cement hydration and moisture diffusion into account synchronously is used to calculate the distribution of interior humidity in concrete. Using the above two models, the distributions of shrinkage strain and stress in concrete columns made by normal and high strength concrete respectively under dry-wet cycles are calculated. The model results show that shrinkage gradient along the radial direction of the column from the center to outer surface increases with age as the outer circumference suffers to dry. The maximum and minimum shrinkage occur at the outer surface and the center of the column, respectively, under drying condition. As wetting starts, the shrinkage strain decreases with increase of interior humidity. The closer to the wetting face, the higher the humidity and the lower the shrinkage strain, as well as the lower the shrinkage stress. As results of the dry-wet cycles acting on the outer circumference of the column, cyclic stress status is developed within the area close to the outer surface of the column. The depth of the influencing zone of dry-wet cyclic action is influenced by concrete strength and dry-wet regime. For low strength concrete, relatively deeper influencing zone is expected compared with that of high strength concrete. The models are verified by concrete-steel composite ring tests and a good agreement between model and test results is found.

  7. STUDIES ON STRENGTH CHARACTERISTICS ON UTILIZATION OF WASTE MATERIALS AS COARSE AGGREGATE IN CONCRETE

    Directory of Open Access Journals (Sweden)

    DR. T. SEKAR

    2011-07-01

    Full Text Available Depletion of natural resources is a common phenomenon in developing countries like India due to rapid urbanization and Industrialization involving construction of Infrastructure and other amenities. In view of this, people have started searching for suitable other viable alternative materials for concrete so that the existing natural resources could be preserved to the possible extent, for the future generation. In this process, different industrial waste materials such as fly ash, blast furnace slag, quarry dust, tile waste, brick bats, broken glass waste, waste aggregate from demolition of structures, ceramic insulator waste, etc. have been tried as a viablesubstitute material to the conventional materials in concrete and has also been succeeded. This paper describes the studies conducted on strength characteristics of concrete made with utilizing waste materials viz: ceramic tiles, ceramic insulator waste, and broken glass pieces. A total number of 24cubes, 24 cylinders and 24 beamswere cast and tested for compressive strength, splitting tensile strength and flexural strength using industrial wastes and the results presented. It was found that, the concrete made of waste ceramic tile aggregate produced more strength in compression, split tensile and flexure than ceramic insulator scrap and broken glass material. This paper recommends that waste ceramic tiles can be used as an alternate construction material to coarse aggregate in concrete.

  8. Caste biology and behaviour of Bulbitermes sarawakensis (Isoptera, Nasutitermitinae) in Malaysia

    NARCIS (Netherlands)

    Lommen, S.T.E.; Huis, van A.; Sajap, A.S.

    2004-01-01

    Morphometrics, caste composition and behaviour were studied in Bulbitermes sarawakensis (Isoptera; Nasutitermitinae) in Malaysia. Morphometric studies displayed two larval stages, a presoldier and a soldier caste, two worker castes and different nymphal stages. Four different nymphs with long wings

  9. Announcement on the Ranking List of China's Large Casting Enterprises in 2005

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ China is the largest country in casting production worldwide and with many excellent casting producers. Advanced manufacturing technology, scientific management ideas, enormous economic benefit in these enterprises makes them the pioneers of the national casting industry.

  10. Fractal structures in casting films from chlorophyll

    Science.gov (United States)

    Pedro, G. C.; Gorza, F. D. S.; de Souza, N. C.; Silva, J. R.

    2014-04-01

    Chlorophyll (Chl) molecules are important because they can act as natural light-harvesting devices during the photosynthesis. In addition, they have potential for application as component of solar cell. In this work, we have prepared casting films from chlorophyll (Chl) and demonstrated the occurrence of fractal structures when the films were submitted to different concentrations. By using optical microscopy and the box-count method, we have found that the fractal dimension is Df = 1.55. This value is close to predicted by the diffusion-limited aggregation (DLA) model. This suggests that the major mechanism - which determines the growth of the fractal structures from Chl molecules - is the molecular diffusion. Since the efficiencies of solar cells depend on the morphology of their interfaces, these finds can be useful to improve this kind of device.

  11. A Review on Radiation Damage in Concrete for Nuclear Facilities: From Experiments to Modeling

    Directory of Open Access Journals (Sweden)

    Beatrice Pomaro

    2016-01-01

    Full Text Available Concrete is a relatively cheap material and easy to be cast into variously shaped structures. Its good shielding properties against neutrons and gamma-rays, due to its intrinsic water content and relatively high-density, respectively, make it the most widely used material for radiation shielding also. Concrete is so chosen as biological barrier in nuclear reactors and other nuclear facilities where neutron sources are hosted. Theoretical formulas are available in nuclear engineering manuals for the optimum thickness of shielding for radioprotection purposes; however they are restricted to one-dimensional problems; besides the basic empirical constants do not consider radiation damage effects, while its long-term performance is crucial for the safe operation of such facilities. To understand the behaviour of concrete properties, it is necessary to examine concrete strength and stiffness, water behavior, volume change of cement paste, and aggregate under irradiated conditions. Radiation damage process is not well understood yet and there is not a unified approach to the practical and predictive assessment of irradiated concrete, which combines both physics and structural mechanics issues. This paper provides a collection of the most distinguished contributions on this topic in the past 50 years. At present a remarkable renewed interest in the subject is shown.

  12. Centerline Depletion in Direct-Chill Cast Aluminum Alloys: The Avalanche Effect and Its Consequence for Turbulent Jet Casting

    Science.gov (United States)

    Wagstaff, Samuel R.; Allanore, Antoine

    2016-07-01

    Avalanche dynamics of sedimenting grains in direct-chill casting of aluminum ingots is investigated as a primary driving force for centerline segregation. An analytical model predicting the importance of avalanche events as a function of casting parameters is proposed and validated with prior art results. New experimental results investigating the transient and steady-state centerline segregation of DC casting with a turbulent jet are reported.

  13. Sense of Place in Environmental Education

    Science.gov (United States)

    Kudryavtsev, Alex; Stedman, Richard C.; Krasny, Marianne E.

    2012-01-01

    Although environmental education research has embraced the idea of sense of place, it has rarely taken into account environmental psychology-based sense of place literature whose theory and empirical studies can enhance related studies in the education context. This article contributes to research on sense of place in environmental education from…

  14. Structure formation of aerated concrete containing waste coal combustion products generated in the thermal vortex power units

    Science.gov (United States)

    Ivanov, A. I.; Stolboushkin, A. Yu; Temlyanstev, M. V.; Syromyasov, V. A.; Fomina, O. A.

    2016-10-01

    The results of fly ash research, generated in the process of waste coal combustion in the thermal vortex power units and used as an aggregate in aerated concrete, are provided. It is established that fly ash can be used in the production of cement or concrete with low loss on ignition (LOI). The permitted value of LOI in fly ash, affecting the structure formation and operational properties of aerated concrete, are defined. During non-autoclaved hardening of aerated concrete with fly ash aggregate and LOI not higher than 2%, the formation of acicular crystals of ettringite, reinforcing interporous partitions, takes place.

  15. Twin-roll strip casting of magnesium alloys in China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The development status of twin-roll strip casting for magnesium alloys in China was summarized as well as the new progress when several kinds of twin-roll strip casting technologies were developed and used.Horizontal twin-roll casting (HTRC) of magnesium alloys has attracted much attention and has been industrialized in China.Vertical twin roll casting(VTRC) of the magnesium alloys can reach a speed of higher than 30 m/min and its research and development are just beginning and exhibit exciting potential.By comparing the process characteristics of the two technologies,the process stability of HTRC for the magnesium alloys is better,and the casting speed and the cooling rate of VTRC for the magnesium alloys are higher.The quality of the products by the two technologies needs to be improved and further investigated.

  16. Formwork pressure exerted by self-consolidating concrete

    Science.gov (United States)

    Omran, Ahmed Fathy

    rate should be optimized to yield a cost effective formwork system. Pausing the continuous casting by a waiting period can reduce the exerted lateral pressure. The research investigation could accelerate the acceptance and implementation of SCC technology in cast-in-place applications, which is the preponderate business of the ready mixed concrete suppliers. The research findings could also contribute to the removal of some of the major barriers hindering the acceptance of SCC in cast-in-place applications and provide the industry with much needed guidelines on formwork pressure. (Abstract shortened by UMI.)

  17. Preliminary engineering and economic analysis of the fixation of high-level radioactive wastes in concrete

    International Nuclear Information System (INIS)

    This feasibility study was based on a waste fixation facility that would serve a reprocessing plant with a capacity of 5 metric tons of uranium per day (MTU/day). Postirradiation cooling times of 3 to 10 years prior to waste solidification were assumed. The waste solution would be concentrated, denitrated, mixed with cement, and cast under pressure in cylindrical canisters similar to those envisioned for a glass facility. The solidified waste grout would be vented, to allow the free water to escape, and then sealed. The filled canisters would be shipped to a geologic repository for permanent storage. Recent work with concretes formed under elevated temperatures and pressures (FUETAP) indicates that they are highly leach resistant. The operating costs were estimated for a waste fixation facility under several conditions. Operating costs for a glass fixation facility were also estimated and compared with the operating costs for a concrete fixation facility. The principal conclusion is that concrete could be an alternative to glass as a matrix for fixation of wastes with high heat-generation rates. The operating costs of an optimized concrete fixation process would probably not be greatly higher than the operating costs of a glass plant, and the capital costs would almost surely be lower. In addition, the concrete process is not a high-temperature process and would not have the consequent operating problems

  18. CONCRETE IN COLD WEATHER CONDITIONS –CHALLANGES – PRECAUTIONS

    OpenAIRE

    Dr.S.Vijaya Mohan Rao

    2016-01-01

    In general, Concrete can be placed safely without damage from freezing throughout the winter months in cold climates if certain precautions are taken. Cold weather is defined as a period when for more than 3 successive days the average daily air temperature drops below 5°C (40°F) and stays below 10°C (50°F) for more than one-half of any 24 hour period (ACI Committee 306). Under these circumstances, all materials and equipment needed for adequate protection and curing must be o...

  19. Optimization of Micro Silica in Light Weight Lika Concrete

    Directory of Open Access Journals (Sweden)

    Alireza M.G. Roshan

    2010-01-01

    Full Text Available Problem statement: In this article, special kind of light weight aggregate named lika had been studied. Approach: The aim of this research was first, to achieve the best mix design of light weight concrete which could be in light weight concrete category and second, by applying the first part gain the main reason of this research which was finding the optimized amount of Micro Silica in a light weight lika concrete. Results: Experimental results had been compared with theoretical viewpoints to reach the properties of the optimized concrete with lika. Conclusion: It is concluded that we can get to a light weight structure concrete applying light aggregate of lika.

  20. An Alternative Mechanism for Accelerated Carbon Sequestration in Concrete

    Energy Technology Data Exchange (ETDEWEB)

    Haselbach, Liv M.; Thomle, Jonathan N.

    2014-07-01

    The increased rate of carbon dioxide sequestration (carbonation) is desired in many primary and secondary life applications of concrete in order to make the life cycle of concrete structures more carbon neutral. Most carbonation rate studies have focused on concrete exposed to air under various conditions. An alternative mechanism for accelerated carbon sequestration in concrete was investigated in this research based on the pH change of waters in contact with pervious concrete which have been submerged in carbonate laden waters. The results indicate that the concrete exposed to high levels of carbonate species in water may carbonate faster than when exposed to ambient air, and that the rate is higher with higher concentrations. Validation of increased carbon dioxide sequestration was also performed via thermogravimetric analysis (TGA). It is theorized that the proposed alternative mechanism reduces a limiting rate effect of carbon dioxide dissolution in water in the micro pores of the concrete.

  1. Relationship Between Casting Distortion, Mold Filling, and Interfacial Heat Transfer in Sand Molds

    Energy Technology Data Exchange (ETDEWEB)

    J. K. Parker; K. A. Woodbury; T. S. Piwonka; Y. Owusu

    1999-09-30

    This project sought to determine the relationship between casting dimensions and interfacial heat transfer in aluminum alloy sand castings. The program had four parts; measurement of interfacial heat transfer coefficients in resin bonded and green sand molds, the measurement of gap formation in these molds, the analysis of castings made in varying gatings, orientations and thicknesses, and the measurement of residual stresses in castings in the as-cast and gate removed condition. New values for interfacial heat transfer coefficients were measured, a novel method for gap formation was developed, and the variation of casting dimensions with casting method, gating, and casting orientation in the mold was documented.

  2. 工程结构中混凝土裂缝控制技术研究%Technology Research on Concrete Crack Control of Engineering Structures

    Institute of Scientific and Technical Information of China (English)

    赵野; 吕子鹏

    2013-01-01

    收缩混凝土结构裂缝是工程应用和学术界长期研究和探讨的重要课题。文章从大体积混凝土结构和砌块住宅结构另方面分析了混凝土裂缝控制的技术,从而分析了现浇混凝土楼板裂缝的危害,提出了现浇混凝土楼板裂缝防治策略。%The shrinkage cracks of concrete structure is an important subject in engineering application and academic circles for a long time of study and discussion. This paper analyzes the concrete crack control technology from a large volume of concrete structure and masonry residential structure on the other hand. It analyses the harm of cast-in-place concrete floor crack, and puts forward the prevention of cracks in cast-in-place concrete floor control strategies.

  3. Beneficial Use of Carbon Dioxide in Precast Concrete Production

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Yixin

    2014-03-31

    The feasibility of using carbon dioxide as feedstock in precast concrete production is studied. Carbon dioxide reacts with calcium compounds in concrete, producing solid calcium carbonates in binding matrix. Two typical precast products are examined for their capacity to store carbon dioxide during the production. They are concrete blocks and fiber‐cement panels. The two products are currently mass produced and cured by steam. Carbon dioxide can be used to replace steam in curing process to accelerate early strength, improve the long‐term durability and reduce energy and emission. For a reaction within a 24‐hour process window, the theoretical maximum possible carbon uptake in concrete is found to be 29% based on cement mass in the product. To reach the maximum uptake, a special process is developed to promote the reaction efficiency to 60‐80% in 4‐hour carbon dioxide curing and improve the resistance to freeze‐thaw cycling and sulfate ion attack. The process is also optimized to meet the project target of $10/tCO{sub 2} in carbon utilization. By the use of self‐concentrating absorption technology, high purity CO{sub 2} can be produced at a price below $40/t. With low cost CO{sub 2} capture and utilization technologies, it is feasible to establish a network for carbon capture and utilization at the vicinity of carbon sources. If all block produces and panel producers in United States could adopt carbon dioxide process in their production in place of steam, carbon utilization in these two markets alone could consume more than 2 Mt CO{sub 2}/year. This capture and utilization process can be extended to more precast products and will continue for years to come.

  4. Beneficial Use of Carbon Dioxide in Precast Concrete Production

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Yixin [McGill Univ., Montreal, QC (Canada)

    2014-06-26

    The feasibility of using carbon dioxide as feedstock in precast concrete production is studied. Carbon dioxide reacts with calcium compounds in concrete, producing solid calcium carbonates in binding matrix. Two typical precast products are examined for their capacity to store carbon dioxide during the production. They are concrete blocks and fiber-cement panels. The two products are currently mass produced and cured by steam. Carbon dioxide can be used to replace steam in curing process to accelerate early strength, improve the long-term durability and reduce energy and emission. For a reaction within a 24-hour process window, the theoretical maximum possible carbon uptake in concrete is found to be 29% based on cement mass in the product. To reach the maximum uptake, a special process is developed to promote the reaction efficiency to 60-80% in 4-hour carbon dioxide curing and improve the resistance to freeze-thaw cycling and sulfate ion attack. The process is also optimized to meet the project target of $10/tCO2 in carbon utilization. By the use of self-concentrating absorption technology, high purity CO2 can be produced at a price below $40/t. With low cost CO2 capture and utilization technologies, it is feasible to establish a network for carbon capture and utilization at the vicinity of carbon sources. If all block produces and panel producers in United States could adopt carbon dioxide process in their production in place of steam, carbon utilization in these two markets alone could consume more than 2 Mt CO2/year. This capture and utilization process can be extended to more precast products and will continue for years to come.

  5. Stress wave communication in concrete: I. Characterization of a smart aggregate based concrete channel

    Science.gov (United States)

    Siu, Sam; Ji, Qing; Wu, Wenhao; Song, Gangbing; Ding, Zhi

    2014-12-01

    In this paper, we explore the characteristics of a concrete block as a communication medium with piezoelectric transducers. Lead zirconate titanate (PZT) is a piezoceramic material used in smart materials intended for structural health monitoring (SHM). Additionally, a PZT based smart aggregate (SA) is capable of implementing stress wave communications which is utilized for investigating the properties of an SA based concrete channel. Our experiments characterize single-input single-output and multiple-input multiple-output (MIMO) concrete channels in order to determine the potential capacity limits of SAs for stress wave communication. We first provide estimates and validate the concrete channel response. Followed by a theoretical upper bound for data rate capacity of our two channels, demonstrating a near-twofold increase in channel capacity by utilizing multiple transceivers to form an MIMO system. Our channel modeling techniques and results are also helpful to researchers using SAs with regards to SHM, energy harvesting and stress wave communications.

  6. Stress wave communication in concrete: I. Characterization of a smart aggregate based concrete channel

    International Nuclear Information System (INIS)

    In this paper, we explore the characteristics of a concrete block as a communication medium with piezoelectric transducers. Lead zirconate titanate (PZT) is a piezoceramic material used in smart materials intended for structural health monitoring (SHM). Additionally, a PZT based smart aggregate (SA) is capable of implementing stress wave communications which is utilized for investigating the properties of an SA based concrete channel. Our experiments characterize single-input single-output and multiple-input multiple-output (MIMO) concrete channels in order to determine the potential capacity limits of SAs for stress wave communication. We first provide estimates and validate the concrete channel response. Followed by a theoretical upper bound for data rate capacity of our two channels, demonstrating a near-twofold increase in channel capacity by utilizing multiple transceivers to form an MIMO system. Our channel modeling techniques and results are also helpful to researchers using SAs with regards to SHM, energy harvesting and stress wave communications. (paper)

  7. Flow modelling of steel fibre reinforced self-compacting concrete

    DEFF Research Database (Denmark)

    Svec, Oldrich

    the casting process of fibre reinforced self-compacting concrete, including the movement of individual immersed fibres in response to such factors as formwork geometry and surface roughness, has profound implications toward the effective use of these materials within the civil infrastructure. Together...... with physical experimentation, this coupled simulation of concrete casting and its load resistance in the hardened state presents opportunities for improving material performance for both ordinary and high-performance applications.......Concrete is one of the most widely used materials in the world. Ordinary concrete composition makes the material strong in compression yet weak and brittle in tension. Steel reinforced concrete successfully eliminates the weak tensile properties of the ordinary concrete. Steel fibres dispersed...

  8. Diffusion behavior of chloride ions in concrete

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, T.; Gjoerv, O.E. [Norwegian Univ. of Science and Technology, Trondheim (Norway). Div. of Building Materials

    1996-06-01

    In the present paper, an analysis of the diffusion behavior of chloride ions in concrete is presented. In concentrated electrolytic aqueous solutions such as seawater or that typically used in laboratory experiments, the effect of ionic interaction may significantly reduce the chemical potential and thus the driving force of the diffusing species. Because of different drift velocities of the cations and chloride ions in the solution, the lagging motion of the cations will also retard the drift velocity of the chlorides. In addition, both the electrical double layer forming on the solid surface and the chemical binding may significantly interfere with the transport of the chloride ions. As a result, the diffusion behavior of the chloride ions in concrete is a more complex and complicated transport process than what can be described by Fick`s law of diffusion.

  9. Places of remembrance in citizenship education

    Directory of Open Access Journals (Sweden)

    KInga Majchrzak

    2012-06-01

    Full Text Available The text starts with a short introduction. Then the concept of place is defined and its inherent characteristics are described: its symbolism, multi-sided nature and multidisciplinary connotations. Afterwards the principles of place-based pedagogy are presented and it’s eclectic character is pointed out. Then, attempt is made to explain the idea of the places of remembrance from the standpoint of history and pedagogy. In the final part the author relates to educational potential of places of remembrance and takes a stance on the role of places of remembrance in citizenship education.

  10. Development of Nano technology in High Performance Concrete

    International Nuclear Information System (INIS)

    Concrete is the most widely used building material all around the world which has been undergoing many changes aligned with technological advancement. The most recent available type of concrete is high performance concrete which is produced by employing different admixtures both chemical and mineral to enhance mechanical properties and durability. Recently, technology has made it easy for scientist to study nano sized admixtures and their effect on microstructure of concrete. This paper reviews nano particles in cement composites and how they can improve different properties of concrete. (author)

  11. Self-compacting concrete mixtures for road BUILDING

    Directory of Open Access Journals (Sweden)

    Tran Tuan My

    2012-10-01

    Therefore, effective concrete road pavements require self-compacting though non-segregating concrete mixtures to comply with the pre-set values of their properties, namely, bending and compressive strength, corrosion resistance, freeze resistance, etc. Acting in cooperation with Department of Technology of Binders and Concretes of MSUCE, NIIMosstroy developed and examined a self-compacting cast concrete mixture designated for durable monolithic road pavements. The composition in question was generated by adding a multi-component modifier into the mix. The modifier was composed of a hyperplasticiser, active (structureless fine and crystalline silica, and a concrete hardening control agent.

  12. Modelling autogenous expansion for magnesia concrete in arch dams

    Institute of Scientific and Technical Information of China (English)

    Feng JIN; Guoxin ZHANG; Xiaoqing LUO; Chuhan ZHANG

    2008-01-01

    Magnesia Concrete is a kind of expansive con-crete used in Chinese hydraulic engineering more and more widely. To evaluate the effects of autogenous expan-sion on the stresses of arch dams, a simple model of auto-genous expansion for Magnesia Concrete in dam engineering is presented. This model is based on three assumptions: 1) the total amount of autogenous expan-sion of Magnesia Concrete is related only to the properties of materials and mixing of concrete; 2) the autogenous expansion of Magnesia Concrete is irreversible due to the irreversibility of hydration reaction of Magnesia in the concrete; 3) the autogenous expansion strain rates of Magnesia Concrete bear a relation between temperature and residual Magnesia per unit volume of concrete. The model is verified by some experimental data of autogen-ous expansion of Magnesia Concrete and field-measured data of an arch dam in China. Embedded into finite ele-ment arch dam simulation software, this model is employed to simulate the effects of autogenous expansion of Magnesia Concrete in hydraulic engineering.

  13. Corrosion inhibition in self-compacting concrete

    OpenAIRE

    Blankson, Marva Angela

    2013-01-01

    This research was undertaken to investigate the effectiveness of carboxylic corrosion inhibitor in fly ash and silica fume (respectively FM and SM) samples and nitrite-based corrosion inhibitors in fly ash (FGC) sample. The findings from this research show that the addition of the carboxylic inhibitor altered the hydration of fly ash and silica fume self-compaction concretes (SCCs) by delaying the formation of ettrngite and the production of portlandite in the FM and SM samples and ultimatel...

  14. Teaching Media Integration in Concrete Technology Course

    Directory of Open Access Journals (Sweden)

    René Antonio Puig Martínez

    2015-01-01

    Full Text Available The Concrete Technology subject, part of the curriculum of Civil Engineering, required for your study multiple and varied teaching media, only way to achieve objectivity in the instruction. The work presented here, aims to unite methodologically the teaching media as a system, aimed at improving knowledge acquisition by students as a more for raising the quality of instruction and learning outcomes. By selecting appropriate teaching media to Concrete Technology subject, the author was supported by the main categories of didactic. The key product of the work is presented as a multimedia organized methodologically for conducting classes and independent study in the subject and in the integrated project for third year. The study results have been validated to date in two courses, contributing to increased student motivation for the subject and better outcomes.

  15. Influences of Short Discrete Fibers in High Strength Concrete with Very Coarse Sand

    Directory of Open Access Journals (Sweden)

    Mahyuddin Ramli

    2010-01-01

    Full Text Available Problem statement: High Strength Concrete (HSC normally content high cementitous amount and low water binder ratio. However, these would cause substantial volume changes to the concrete and therefore affected the strength development. In addition, the brittleness of HSC was increased when silica fume used as partial cement replacement to achieve high strength. Approach: This study discussed the effects of incorporated short discrete Coconut Fibers (CF, Barchip Fibers (BF and Glass Fibers (GF into HSC to enhance the performance of concrete while kept the binder content at moderate level. Additional specialty to this HSC was casted with very coarse sand with fineness modulus of 3.98. A total of thirteen mixes were casted and tested for slump, density, compressive strength, flexural strength and ultrasonic pulse velocity in accordance with British Standards. Results: The slump was slightly reduced by the short discrete fibers. All of the fibrous specimens had lower density than control. However, the compressive strength of the HSC had increased from 71.8-79.0 MPa using 1.8% of BF, while flexural strength had increased from 5.21-6.50 MPa. All specimens showed that ultrasonic velocity higher than 4.28 km sec-1. Conclusion/Recommendations: In short, combination of incorporated short discrete fibers and applied very coarse sand to produce HSC showed very satisfying results and improvements. Further assessment on durability and impact resistivity will be verified in the coming research.

  16. Recycling of PET bottles as fine aggregate in concrete.

    Science.gov (United States)

    Frigione, Mariaenrica

    2010-06-01

    An attempt to substitute in concrete the 5% by weight of fine aggregate (natural sand) with an equal weight of PET aggregates manufactured from the waste un-washed PET bottles (WPET), is presented. The WPET particles possessed a granulometry similar to that of the substituted sand. Specimens with different cement content and water/cement ratio were manufactured. Rheological characterization on fresh concrete and mechanical tests at the ages of 28 and 365days were performed on the WPET/concretes as well as on reference concretes containing only natural fine aggregate in order to investigate the influence of the substitution of WPET to the fine aggregate in concrete. It was found that the WPET concretes display similar workability characteristics, compressive strength and splitting tensile strength slightly lower that the reference concrete and a moderately higher ductility. PMID:20176466

  17. Attenuation of gamma radiation in concrete shields

    International Nuclear Information System (INIS)

    The attenuation characteristics of γ radiation in concrete layers considering their mechanical resistence and densities were determined. A 137Cs source was used in a 'good geometry' arrangement to eliminate the effects of the buildup factor. The ordinary and the heavy concrete were irradiated and for the latter it was used as additives iron ore and Fe2O3 pellets in various grain sizes. The detection system consisted of a 2' x 2' NaI (Tl) crystal coupled to a photomultiplier tube and the associated electronic equipment. FORTRAN programs were used for determining the absorption coefficients and the attenuation factors. These programs calculate photopeak areas eliminating all contributions due to Compton effect and background. (Author)

  18. Development of chloride-induced corrosion in pre-cracked RC beams under sustained loading: Effect of load-induced cracks, concrete cover, and exposure conditions

    International Nuclear Information System (INIS)

    This paper deals with corrosion initiation and propagation in pre-cracked reinforced concrete beams under sustained loading during exposure to a chloride environment. Specimen beams that were cast in 2010 were compared to specimens cast in 1984. The only differences between the two sets of beams were the casting direction in relation to tensile reinforcement and the exposure conditions in the salt-fog chamber. The cracking maps, corrosion maps, chloride profiles, and cross-sectional loss of one group of two beams cast in 2010 were studied and their calculated corrosion rates were compared to that of beams cast in 1984 in order to investigate the factors influencing the natural corrosion process. Experimental results show that, after rapid initiation of corrosion at the crack tip, the corrosion process practically halted and the time elapsing before corrosion resumed depended on the exposure conditions and cover depth

  19. Development of chloride-induced corrosion in pre-cracked RC beams under sustained loading: Effect of load-induced cracks, concrete cover, and exposure conditions

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Linwen [Université de Toulouse, UPS, INSA, LMDC, Toulouse (France); Université de Sherbrooke, Quebec (Canada); François, Raoul, E-mail: raoul.francois@insa-toulouse.fr [Université de Toulouse, UPS, INSA, LMDC, Toulouse (France); Dang, Vu Hiep [Hanoi Architectural University, Faculty of Civil Engineering, Hanoi (Viet Nam); L' Hostis, Valérie [CEA Saclay, CEA, DEN, DPC, SECR, Laboratoire d' Etude du Comportement des Bétons et des Argiles, Gif-sur-Yvette (France); Gagné, Richard [Université de Sherbrooke, Quebec (Canada)

    2015-01-15

    This paper deals with corrosion initiation and propagation in pre-cracked reinforced concrete beams under sustained loading during exposure to a chloride environment. Specimen beams that were cast in 2010 were compared to specimens cast in 1984. The only differences between the two sets of beams were the casting direction in relation to tensile reinforcement and the exposure conditions in the salt-fog chamber. The cracking maps, corrosion maps, chloride profiles, and cross-sectional loss of one group of two beams cast in 2010 were studied and their calculated corrosion rates were compared to that of beams cast in 1984 in order to investigate the factors influencing the natural corrosion process. Experimental results show that, after rapid initiation of corrosion at the crack tip, the corrosion process practically halted and the time elapsing before corrosion resumed depended on the exposure conditions and cover depth.

  20. Fatigue Strain and Damage Analysis of Concrete in Reinforced Concrete Beams under Constant Amplitude Fatigue Loading

    Directory of Open Access Journals (Sweden)

    Fangping Liu

    2016-01-01

    Full Text Available Concrete fatigue strain evolution plays a very important role in the evaluation of the material properties of concrete. To study fatigue strain and fatigue damage of concrete in reinforced concrete beams under constant amplitude bending fatigue loading, constant amplitude bending fatigue experiments with reinforced concrete beams with rectangular sections were first carried out in the laboratory. Then, by analyzing the shortcomings and limitations of existing fatigue strain evolution equations, the level-S nonlinear evolution model of fatigue strain was constructed, and the physical meaning of the parameters was discussed. Finally, the evolution of fatigue strain and fatigue damage of concrete in the compression zone of the experimental beam was analyzed based on the level-S nonlinear evolution model. The results show that, initially, fatigue strain grows rapidly. In the middle stages, fatigue strain is nearly a linear change. Because the experimental data for the third stage are relatively scarce, the evolution of the strain therefore degenerated into two phases. The model has strong adaptability and high accuracy and can reflect the evolution of fatigue strain. The fatigue damage evolution expression based on fatigue strain shows that fatigue strain and fatigue damage have similar variations, and, with the same load cycles, the greater the load level, the larger the damage, in line with the general rules of damage.

  1. Fastening elements in concrete structures - numerical simulations

    OpenAIRE

    Ozbolt, Josko; Eligehausen, Rolf

    1993-01-01

    Anchoring elements such as headed and expansion studs and grouted or undercut anchors, are often used for local transfer of loads into concrete members. In order to better understand the failure mechanism, a large number of experiments have been carried out in the past. However, due to the complicated three-dimensional load transfer a very few or no numerical studies have been performed for a number of different fastening situations i.e. influence of the embedment depth, crack-width inftuence...

  2. Influence of Binder Composition and Concrete Pore Structure on Chloride Diffusion Coefficient in Concrete

    Institute of Scientific and Technical Information of China (English)

    LI Pengping; SU Dagen; WANG Shengnian; FAN Zhihong

    2011-01-01

    The influence of binder composition and pore structure of concrete on chloride diffusion coefficient in concrete were investigated by the natural immersion test, MIP test, SEM and EDS test, respectively. The experimental results showed that the effect of binder composition on chloride diffusion coefficient was the comprehensive result of concrete pore structure and binder hydration products, and the porosity and pore size distribution were the main factors that influence the changes of diffusion coefficient. The chloride diffusion coefficient decreased with increasing the curing temperature and the relative humidity. The hydration degree were promoted by improving curing temperatures, and then the porosity of concrete decreased and the proportion of gel pore and transitional pore increased, respectively. But the water evaporation decreased with increasing the relative humidity and then decreased porosity and increased the proportion of gel pore and transitional pore. Additionally, The chloride diffusion coefficient of concrete got the lower value when the appropriate replacement of fly ash in the ranges of 10%-20%, when the double-adding fly ash and slag content was 50%. The porosity increased and the ratio of C/S in C-S-H decreased with further increasing the fly ash content, which led to increase the chloride diffusion coefficient in concrete.

  3. Study on durability of concrete in coal mine

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.; Jin, Z.; Sun, W.; Guan, X. [Henan Polytechnic University, Jiaozuo (China). Dept. of Resource and Material

    2004-12-01

    There are sulfate and chloride ions corrosion and carbonation of concrete in coal mine. Based on taking test of accelerated carbonation, corrosion of 3.5% weight of NaCl solution and 5% weight of Na{sub 2}SO{sub 4} solution of coal mine concretes, durability of concretes which include spray concrete of C20, high performance concretes of C30 and C50 and effect of fly ash on durability have been studied. Results suggest that the coal mineral high performance concretes show good resistance capacities of carbonation, and sulfate and chloride corrosion to meet the coal mine construction. Moreover, fly ash improves resistance capacity of high performance concrete (HPC) to chloride and sulfate but decreases the resistance capacity of C30's to carbonation and average dynamic modulus. 9 refs., 4 figs., 1 tab.

  4. Study on durability of concrete in coal mine

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yi-shun; JIN Zu-quan; SUN Wei; GUAN Xue-mao

    2004-01-01

    There are sulfate and chloride ions corrosion and carbonation to concrete in coal mine. Based on taking test of accelerated carbonation, corrosion of 3.5% weight of NaCl solution and 5% weight of Na2SO4 solution of coal mine concretes, durability of concretes which include spray concrete of C20, high performance concretes of C30 and C50and effect of fly ash on durability have been studied. Results suggest that the coal mineral high performance concretes show good resistance capacities of carbonation, sulfate and chloride corrosion to meet the coal mine construction. And the higher the strength grade is,the better the resistance capacity of corrosion of carbonation is, chloride and sulfate.Moreover, fly ash improves resistance capacity of high performance concrete(HPC) to chloride and sulfate but decreases the resistance capacity of C30's to carbonation and average dynamic modulus.

  5. Internal Heterogeneity in a Reactive Powder Concrete

    OpenAIRE

    Bayard, O; Ple, O; Bernier, G

    2004-01-01

    International audience Reactive Powder Concrete (RPC) is made of a very fine homogeneous and compact matrix with short steel fibres. Internal heterogeneities in the material induce heterogeneities of the mechanical characteristics. Elastic fields are disturbed by the presence of fibres. These fields within the matrix, such as load transfers, which operate between fibres and the surrounding matrix, depend not only on the mechanical characteristics of each component, but also on the local pe...

  6. Valorization of Local Mineral Admixtures in Concretes

    Directory of Open Access Journals (Sweden)

    Boudchicha Abdelaziz

    2014-04-01

    Full Text Available This study is an extension of previous researches on mortars with mineral admixtures and super-plasticizers. In this way, the same methodology was applied to concretes and the use of mineral admixture was limited to low cost materials available in Algeria as limestone, pozzolan and blast furnace slag, with current cement and super-plasticizer. The experimental methodology used was based on the volume substitution of the cement by admixtures in mixtures with the absolute volume of the solid phases and workability preserved constant. The main results achieved showed that the super-plasticizer demand of concretes depends on the nature and the quantity of the incorporated admixture. The combined use of admixtures and super-plasticizer has generally a favourable effect on compressive strengths at 07 and 28 days at low rates of cement substitution, which vary significantly with the nature, fineness and quantity of the used admixtures. At 07 days, limestone admixtures give better improvements and reach more than 20 % of gain to the compressive strength of the reference concrete with no admixtures or super-plasticizer, at 10 % of the cement substitution and still better until 30 %. At 28 days, blast furnace slag admixtures give better improvements at 28 days and reach more than 20 % of gain to the compressive strength of the reference concrete at 20 % of the cement substitution and still better until 30 %. This contribution to the compressive strength is explained on the one hand by the reduction of the quantity of water in the mixtures at the same consistency, by the use of the super-plasticizer and on another hand by the activity of Limestone admixtures at early ages and to the latent hydraulic properties of blast furnace slag at 28 days.

  7. Solidification science in cast MMCs: The influence of merton flemings

    Science.gov (United States)

    Rohatgi, Pradeep; Asthana, Rajiv

    2001-09-01

    The solidification science of cast metalmatrix composites (MMC) evolved as a subset of the broad field of solidification of monolithic alloys pioneered by Merton Flemings and his students. As a result of advances in solidification, the cast MMC field has evolved from its early incarnation—employing empirical research to engineer novel materials using versatile and cost-effective casting techniques—to using solidification-science-based approaches to tailor advanced materials for application-specific needs. The current and emerging applications of cast MMCs in a variety of automotive, aerospace, electronic packaging, and consumer-good industries exemplify the maturity of the field and the materials. Innovations in composite-forming techniques and efforts at wider industrial acceptance of MMCs will undoubtedly continue. However, the scientific principles underlying the solidification microstructure evolution that governs the composite properties have become well established, to a great extent, due to Flemings’ early, pioneering work on monolithic alloys and some of his more recent studies on solidification of reinforced metals. This paper reviews some aspects of solidification of discontinuously reinforced cast metals that owe their current understanding to Flemings’ contributions, in particular, the scientific understanding of macro- and microsegregation, fluidity and rheology of multiphase slurries, and stircasting, semi-solid casting, and preform infiltration. Current research to develop and test prototype components made from cast composites, including Al-flyash, Cu-graphite, Al-graphite, Al-alumina, and SiC-Al, is also presented, along with directions for future research.

  8. Dynamic control of crystallinity in polymer film casting process

    Directory of Open Access Journals (Sweden)

    Thananchai Leephakpreeda

    2005-05-01

    Full Text Available This paper presents an approach for dynamic control of crystallinity in polymer film casting process. As known, the transients of crystallization dictate the microstructures of semi-crystalline polymer during solidification. In turn, the properties of finished products can be determined by adjustable variables in polymer film casting process such as temperature of chill roll. In this work, an experimental model of the solidification in film casting process is derived by a system identification technique. This model is used to design a digital feedback controller including a state estimator. The simulation results show the effectiveness of the proposed control technique on an extruded film.

  9. Properties of Self-Compacting Concrete Incorporating Waste Foundry Sand

    OpenAIRE

    Rafat SIDDIQUE; Ravinder Kaur SANDHU

    2013-01-01

    This paper demonstrates the possibilities of using waste foundry sand as partial replacement of sand in self-compacting concrete. Self-compacting concrete, as the name indicates, is a type of concrete that does not require external or internal compaction, because it becomes levelled and consolidated under its self-weight. Foundry sand is high quality silica sand used as a moulding material by ferrous and non-ferrous metal casting industries. It can be reused several times in foundries but, af...

  10. Retention of Lead and Total Suspended Solids in Pervious Concrete

    Science.gov (United States)

    Nolin, Spring

    Pervious concrete, an alternative to conventional concrete, is a material with an increased amount of void space that allows water to pass through the concrete versus ponding and/or running off into catchment systems. This study examines the retention capabilities of lead and Total Suspended Solids (TSS) within an entire pervious concrete system and the effects of different fly ash compositions for pervious concrete along with two different types of crushed stones and a soil layer. A complete pervious concrete system consisted of one formulation of pervious concrete along with one type of crushed stone and the soil layer used in the individual trials of TSS removal and lead retention to determine if a complete pervious concrete system would equal the sum of its parts. The retention of lead by the complete pervious concrete system was compared against the individual results from the parts of the complete pervious concrete system. Among the different formulations of pervious concrete, the specimens with a high loss on ignition showed a higher removal rate of lead but not TSS than those with low loss on ignition, yet the difference in the percentage of fly ash did not show an effect on the removal or retention of either lead or TSS. Of the two types of crushed stone tested, the 3/8" crushed stone retained more TSS than the #57 crushed stone. The amount of lead retained by the #57 crushed stone was not significantly different from the 3/8" crushed stone after the crushed stone was flushed. The dirt layer showed a complete removal rate of lead as did the complete pervious concrete system. The sum of the parts of the pervious concrete system indicate that for maximum removal of TSS and lead, a high loss on ignition fly ash pervious concrete cylinder should be used in conjunction with a 3/8" crushed stone layer.

  11. Effect of Fractal Dimension of Fine Aggregates on the Concrete Chloride Resistance

    OpenAIRE

    Xue, Wen; J. Chen

    2016-01-01

    The relationship between fractal dimension of fine aggregates and the chloride resistance of concrete was investigated in this study. Both concrete and mortar specimens were cast. Concrete specimens were in the same mix design as the mortar specimens except for the coarse aggregates. The specimens were divided into different groups based on the gradation of the fine aggregates. The chloride resistances of concrete specimens were tested by using the rapid chloride migration method. The results...

  12. Carbides in Nodular Cast Iron with Cr and Mo

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2007-07-01

    Full Text Available In these paper results of elements microsegregation in carbidic nodular cast iron have been presented. A cooling rate in the centre of the cross-section and on the surface of casting and change of moulding sand temperature during casting crystallization and its self-cooling have been investigated. TDA curves have been registered. The linear distribution of elements concentration in an eutectic grain, primary and secondary carbides have been made. It was found, that there are two kinds of carbides: Cr and Mo enriched. A probable composition of primary and secondary carbides have been presented.

  13. Solute distribution in columnar crystal zone of continuous casting billets

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The periodic bending deformation in the direction of casting occurs at the liquid/solid interface of billet due to the roller supporting force and the pressure of molten metal in the process of continuous casting. Based on this fact, a qualitative expression of solute concentration in columnar crystal zone for continuous casting billet is established, which agrees with the experimental results basically. Therefore, it is favorable to gain a columnar structure with less segregation by adopting a caster with compactly distributed small rollers and enhancing the cooling intensity in secondary-cooling zone.

  14. Rotational Capacity of Reinforced Concrete Beams

    DEFF Research Database (Denmark)

    Ulfkjær, J. P.; Henriksen, M. S.; Brincker, Rune;

    1995-01-01

    The European Structural Integrity Society-Technical Committee 9, has initiated a Round Robin on 'Scale Effects and Transitional Failure Phenomena of Reinforced Concrete Beams in Flexure'. In Denmark, Aalborg University is participating. The programme for Aalborg University involves an experimental...... programme where 120 reinforced concrete beams, 54 plain concrete beams and 324 concrete cylinders are tested. For the reinforced concrete beams four different parar meters are varied. The slenderness is 6, 12 and 18, the beam depth is 100 mm, 200 mm and 400 mm giving nine different geometries, five...... reinforcement ratios between 0.14% and 1.57%, and the concrete has a compressive strength of approximately 60 MPa or 90 MPa. The beams are tested in threepoint bending in a servo controlled materials testing system specially designed for the wide range of geometries The casting of the beams is finished. The...

  15. Cool Stars in Hot Places

    OpenAIRE

    Megeath, S. T.; Gaidos, E.; Hester, J. J.; Adams, F. C.; Bally, J.; Lee, J. -E.; Wolk, S.

    2007-01-01

    During the last three decades, evidence has mounted that star and planet formation is not an isolated process, but is influenced by current and previous generations of stars. Although cool stars form in a range of environments, from isolated globules to rich embedded clusters, the influences of other stars on cool star and planet formation may be most significant in embedded clusters, where hundreds to thousands of cool stars form in close proximity to OB stars. At the cool stars 14 meeting, ...

  16. The Poorest Place in America

    Institute of Scientific and Technical Information of China (English)

    JackeWhite; 李小平

    2000-01-01

    The town has no public parks or swimming pools, no movie theaters, no shopping malls, not even a McDonald's or a WalMart. In fact, business in Lake Providence,Louisiana, is so bad that even the pawnshop has shut down. " The only recreation we

  17. Put Yourself in My Place

    Science.gov (United States)

    Schuller, Tom

    2011-01-01

    As the riots in England demonstrated this summer, lack of empathy is a key factor in explaining people's readiness to commit crimes. How one acquires empathy is a major challenge to one's learning. Adult education has historically provided the spaces where people can both reassert and develop their particular collective identity and also learn…

  18. A Place in the Sun.

    Science.gov (United States)

    Booth, Bibi; Brook, Richard; Rieben, Elizabeth; Wooster, Elizabeth

    2001-01-01

    Describes life in the Mojave Desert. Includes a map of the desert and a poster that can be used in the classroom with drawings and photographs of desert creatures. Presents three lesson plans on mapping deserts, earthshaking events, and weed invaders as well as a section of teacher resources. (SAH)

  19. Booking His Place in History

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Late American Pulitzer Prize-winner John Updike is remembered in China The news of the passing of American literary icon John Updike saddened the whole world.In China,the 76-year-old Pulitzer Prize-winning novelist,who

  20. Effects of casting speed on microstructure and segregation of electromagnetically stirred Aluminum alloy in continuous casting process

    Institute of Scientific and Technical Information of China (English)

    LEE Dock-Young; KANG Suk-Won; CHO Duck-Ho; KIM Ki-Bae

    2006-01-01

    Recently, a semi-solid metal processing has been acknowledged as a cost-effective technique to be able to manufacture high quality product for the transportation industry.In this study a hypo-eutectic Al alloy was fabricated by means of an electromagnetic stirrer in continuous casting process and the microstructural change during solidification due to a fluid flow by electromagnetic stirring was examined.Due to the forced fluid flow during solidification a dendritic phase of primary α phase of Al alloy was turned into a globular phase, which can make the Al alloy get a thixotropic behavior in the semi-solid region.In order to establish the quantitative relationship between microstructure and the process parameters, the morphology shape, a silicon distribution and a size of primary α phase were observed according to casting speed in continuous casting machine.The primary α phase was turned into the degenerate dendrites approaching a spherical configuration with increasing casting speed.The fine-grained and equiaxed microstructure appeared at higher casting speed.A segregation behavior of Si element was declined with increasing casting speed and a very uniform distribution of Si element was observed on the billet at a casting speed of 600 mm·min-1.A thickness of the solidifying shell of the billet was shortened with increasing the casting speed.

  1. New Singularities in Unexpected Places

    CERN Document Server

    Barrow, John D

    2015-01-01

    Spacetime singularities have been discovered which are physically much weaker than those predicted by the classical singularity theorems. Geodesics evolve through them and they only display infinities in the derivatives of their curvature invariants. So far, these singularities have appeared to require rather exotic and unphysical matter for their occurrence. Here we show that a large class of singularities of this form can be found in a simple Friedmann cosmology containing only a scalar-field with a power-law self-interaction potential. Their existence challenges several preconceived ideas about the nature of spacetime singularities and impacts upon the end of inflation in the early universe.

  2. Grouted jetted precast concrete sheet piles: Method, experiments, and applications

    OpenAIRE

    Xu, GH; Yue, ZQ; Liu, DF; He, FR

    2006-01-01

    This paper introduces an innovative technology - grouted jetted precast concrete piling - that increases the efficiency of piling operations in coastal regions. The technology includes the following steps: (i) casting concrete piles factory-designed especially for jetting and grouting; (ii) jetting to drive the concrete piles with a crane on a floating ship or platform into soil; and (iii) grouting to enhance the sheet pile connections and to increase the pile bearing capacity. This technolog...

  3. Residual stresses in a cast iron automotive brake disc rotor

    Energy Technology Data Exchange (ETDEWEB)

    Ripley, Maurice I. [Australian Nuclear Scinece and Technology Organisation, PMB 1, Menai, NSW 2234 (Australia)]. E-mail: m.ripley@ansto.gov.au; Kirstein, Oliver [Australian Nuclear Scinece and Technology Organisation, PMB 1, Menai, NSW 2234 (Australia)

    2006-11-15

    Runout, and consequent juddering and pulsation through the brake pedal, is a multi-million dollar per year warranty problem for car manufacturers. There is some suspicion that the runout can be caused by relaxation of residual casting stresses when the disc is overheated during severe-braking episodes. We report here neutron-diffraction measurements of the levels and distribution of residual strains in a used cast iron brake disc rotor. The difficulties of measuring stresses in grey cast iron are outlined and three-dimensional residual-strain distributions are presented and their possible effects discussed.

  4. Inverse thermal analysis method to study solidification in cast iron

    DEFF Research Database (Denmark)

    Dioszegi, Atilla; Hattel, Jesper

    2004-01-01

    Solidification modelling of cast metals is widely used to predict final properties in cast components. Accurate models necessitate good knowledge of the solidification behaviour. The present study includes a re-examination of the Fourier thermal analysis method. This involves an inverse numerical...... solution of a 1-dimensional heat transfer problem connected to solidification of cast alloys. In the analysis, the relation between the thermal state and the fraction solid of the metal is evaluated by a numerical method. This method contains an iteration algorithm controlled by an under relaxation term...... inverse thermal analysis was tested on both experimental and simulated data....

  5. Residual stresses in a cast iron automotive brake disc rotor

    International Nuclear Information System (INIS)

    Runout, and consequent juddering and pulsation through the brake pedal, is a multi-million dollar per year warranty problem for car manufacturers. There is some suspicion that the runout can be caused by relaxation of residual casting stresses when the disc is overheated during severe-braking episodes. We report here neutron-diffraction measurements of the levels and distribution of residual strains in a used cast iron brake disc rotor. The difficulties of measuring stresses in grey cast iron are outlined and three-dimensional residual-strain distributions are presented and their possible effects discussed

  6. Everything in its right place

    NARCIS (Netherlands)

    Fluitman, S.B.A.H.A.

    2011-01-01

    This thesis aimed at exploring immunological aspects of mainly obsessive compulsive disorder (OCD) as well as generalized social anxiety disorder (GSAD), major depressive disorder (MDD) and psychosis. First we reviewed nearly 100 clinical studies on immunological disturbancesin anxiety disorders.In

  7. Thirsty Plants in Arid Places

    Science.gov (United States)

    Schaffer, Linda; Kingsley, Karla V.

    2009-01-01

    In order to demonstrate how plants remove water from the soil and release it to the atmosphere, students compared open- and closed-growing systems using drought-tolerant and higher water requirement plants. Then, students designed a drought-tolerant garden demonstrating what they had learned. Through this experience, students not only learned…

  8. Pervious Concrete

    OpenAIRE

    Torsvik, Øyvind André Hoff

    2011-01-01

    Pervious concrete is a type of concrete with little or no fines which give a large void. This enables high permeability and because of this it enables water to percolate through the concrete. Pervious concrete have been used in many years both as pavement material and on several other applications in the U.S and in other countries in Western Europe. In Norway pervious concrete is not currently in use. This thesis aims to investigate if pervious concrete can withstand the harsh Norwegian clima...

  9. Concrete quality assurance

    Energy Technology Data Exchange (ETDEWEB)

    Holz, N. [Harza Engineering Company, Chicago, IL (United States)

    2000-08-01

    This short article reports on progress at the world's largest civil construction project, namely China's Three Gorges hydro project. Work goes on around the clock to put in place nearly 28 M m{sup 3} of concrete. At every stage of the work there is strong emphasis on quality assurance (QA) and concrete is no exception. The US company Harza Engineering has been providing QA since the mid-1980s and concrete QA has been based on international standards. Harza personnel work in the field with supervisors developing educational tools for supervising concrete construction and quality, as well as providing training courses in concrete technology. Some details on flood control, capacity, water quality and environmental aspects are given..

  10. Put waste in its place

    CERN Multimedia

    2009-01-01

    It doesn’t take much of an effort to sort waste, but what a difference it can make - to the environment, of course, but also to CERN’s incineration bill. A variety of containers are provided to allow waste to be sorted before disposal, thereby making recycling easier. Everyone knows that sorting waste reduces pollution. By recycling or recovering waste materials, we can reduce the amount of waste that ends up in an incinerator or land-fill, while giving the used material a second life. That reduces the consumption of raw materials and natural resources—and of budget resources. CERN pays lower bill: disposing of a tonne of waste by incineration costs 230 Swiss francs, while a tonne of paper only costs 10 francs to dispose of. The problem is that much of the waste is not properly sorted. "In 2008, out of more than 1600 tonnes of waste we had to incinerate 600 tonnes, which is an enormous figure!" says Martine Auerbach, wh...

  11. The degradation processes in high loaded casts

    Directory of Open Access Journals (Sweden)

    E. Ďuriníková

    2010-01-01

    Full Text Available In this work are described structural changes of jet engine DV – 2 turbine blades and effect of degradation process. Turbine blades work in aggressively environs and because of that there are rate among high loaded cast stock. As an experimental material we have chose nickel superalloy ŽS6K with surface heat - resisting alitize layer. Evaluation is slant on largeness wearing over work of certain number of hour in operation. Effect working environs and overrun working temperatures is show changes measures as well as changes macrostructure of basic material blades. Evaluate is advance quantitative metallography through the medium metallographic software NIS element. Quantitative analysis evaluate thickness measures, quality control outer look and lack mixture in the seat, which is not splash, is precede by lack of near another applied protective layer. Allowance is knot on last examination in the area ratings protective heat-resisting layers and gives records for others possible ratings and experiments in this area.

  12. Determination of Bulk Dimensional Variation in Castings

    Energy Technology Data Exchange (ETDEWEB)

    Dr. James F. Cuttino Dr. Edward P. Morse

    2005-04-14

    The purpose of this work is to improve the efficiency of green sand foundries so that they may continue to compete as the most cost-effective method of fabrication while meeting tightening constraints on near-net shape manufacturing. In order to achieve this objective, the study is divided into two major components. The first component concentrated on identifying which processes control surface finish on the castings and which provide potential reductions in variations. The second component identified metrological methods that effectively discern between the geometry of bulk material versus surface finish in order to more accurately determine the quality of a part. The research resulted in the determination of an empirical relationship relating pouring parameters to dimensional variation, with an R2 value of greater than 0.79. A significant difference in variations obtained from vertical vs. horizontal molding machines was also noticed. When analyzed separately, however, the resulting empirical relationships for horizontal and vertical machines had reduced R2 values, probably due to the reduced data sets. Significant parameters when considering vertical and horizontal molding machines together included surface roughness, pattern type, iron type, pouring rate, copper content, amount of Western Bentonite, and permeability.

  13. Review of concrete biodeterioration in relation to nuclear waste.

    Science.gov (United States)

    Turick, Charles E; Berry, Christopher J

    2016-01-01

    Storage of radioactive waste in concrete structures is a means of containing wastes and related radionuclides generated from nuclear operations in many countries. Previous efforts related to microbial impacts on concrete structures that are used to contain radioactive waste showed that microbial activity can play a significant role in the process of concrete degradation and ultimately structural deterioration. This literature review examines the research in this field and is focused on specific parameters that are applicable to modeling and prediction of the fate of concrete structures used to store or dispose of radioactive waste. Rates of concrete biodegradation vary with the environmental conditions, illustrating a need to understand the bioavailability of key compounds involved in microbial activity. Specific parameters require pH and osmotic pressure to be within a certain range to allow for microbial growth as well as the availability and abundance of energy sources such as components involved in sulfur, iron and nitrogen oxidation. Carbon flow and availability are also factors to consider in predicting concrete biodegradation. The microbial contribution to degradation of the concrete structures containing radioactive waste is a constant possibility. The rate and degree of concrete biodegradation is dependent on numerous physical, chemical and biological parameters. Parameters to focus on for modeling activities and possible options for mitigation that would minimize concrete biodegradation are discussed and include key conditions that drive microbial activity on concrete surfaces. PMID:26397745

  14. Review of concrete biodeterioration in relation to nuclear waste.

    Science.gov (United States)

    Turick, Charles E; Berry, Christopher J

    2016-01-01

    Storage of radioactive waste in concrete structures is a means of containing wastes and related radionuclides generated from nuclear operations in many countries. Previous efforts related to microbial impacts on concrete structures that are used to contain radioactive waste showed that microbial activity can play a significant role in the process of concrete degradation and ultimately structural deterioration. This literature review examines the research in this field and is focused on specific parameters that are applicable to modeling and prediction of the fate of concrete structures used to store or dispose of radioactive waste. Rates of concrete biodegradation vary with the environmental conditions, illustrating a need to understand the bioavailability of key compounds involved in microbial activity. Specific parameters require pH and osmotic pressure to be within a certain range to allow for microbial growth as well as the availability and abundance of energy sources such as components involved in sulfur, iron and nitrogen oxidation. Carbon flow and availability are also factors to consider in predicting concrete biodegradation. The microbial contribution to degradation of the concrete structures containing radioactive waste is a constant possibility. The rate and degree of concrete biodegradation is dependent on numerous physical, chemical and biological parameters. Parameters to focus on for modeling activities and possible options for mitigation that would minimize concrete biodegradation are discussed and include key conditions that drive microbial activity on concrete surfaces.

  15. Prompt gamma analysis of chlorine in concrete for corrosion study.

    Science.gov (United States)

    Naqvi, A A; Nagadi, M M; Al-Amoudi, O S B

    2006-02-01

    Measurement of chlorine in concrete is very important for studying of corrosion of reinforcing steel in concrete. Corrosion of reinforcing steel is primarily ascribed to the penetration of chloride ions to the steel surface. Preventive measures for avoiding concrete structure reinforcement corrosion requires monitoring the chloride ion concentration in concrete so that its concentration does not exceed a threshold limit to initiate reinforcement concrete corrosion. An accelerator based prompt gamma neutron activation analysis (PGNAA) setup has been developed for non-destructive analysis of elemental composition of concrete samples. The setup has been used to measure chlorine concentration in concrete samples over a 1-3 wt% concentration range. Although a strong interference has been observed between the chlorine gamma-rays and calcium gamma-rays from concrete, the chlorine concentration in concrete samples has been successfully measured using the 1.164 and 7.643 MeV chlorine gamma-rays. The experimental data were compared with the results of the Monte Carlo simulations. An excellent agreement has been achieved between the experimental data and results of Monte Carlo simulations. The study has demonstrated the successful use of the accelerator-based PGNAA setup in non-destructive analysis of chlorine in concrete samples. PMID:16129605

  16. Use of freeze-casting in advanced burner reactor fuel design

    Energy Technology Data Exchange (ETDEWEB)

    Lang, A. L.; Yablinsky, C. A.; Allen, T. R. [Dept. of Engineering Physics, Univ. of Wisconsin Madison, 1500 Engineering Drive, Madison, WI 53711 (United States); Burger, J.; Hunger, P. M.; Wegst, U. G. K. [Thayer School of Engineering, Dartmouth College, 8000 Cummings Hall, Hanover, NH 03755 (United States)

    2012-07-01

    This paper will detail the modeling of a fast reactor with fuel pins created using a freeze-casting process. Freeze-casting is a method of creating an inert scaffold within a fuel pin. The scaffold is created using a directional solidification process and results in open porosity for emplacement of fuel, with pores ranging in size from 300 microns to 500 microns in diameter. These pores allow multiple fuel types and enrichments to be loaded into one fuel pin. Also, each pore could be filled with varying amounts of fuel to allow for the specific volume of fission gases created by that fuel type. Currently fast reactors, including advanced burner reactors (ABR's), are not economically feasible due to the high cost of operating the reactors and of reprocessing the fuel. However, if the fuel could be very precisely placed, such as within a freeze-cast scaffold, this could increase fuel performance and result in a valid design with a much lower cost per megawatt. In addition to competitive costs, freeze-cast fuel would also allow for selective breeding or burning of actinides within specific locations in fast reactors. For example, fast flux peak locations could be utilized on a minute scale to target specific actinides for transmutation. Freeze-cast fuel is extremely flexible and has great potential in a variety of applications. This paper performs initial modeling of freeze-cast fuel, with the generic fast reactor parameters for this model based on EBR-II. The core has an assumed power of 62.5 MWt. The neutronics code used was Monte Carlo N-Particle (MCNP5) transport code. Uniform pore sizes were used in increments of 100 microns. Two different freeze-cast scaffold materials were used: ceramic (MgO-ZrO{sub 2}) and steel (SS316L). Separate models were needed for each material because the freeze-cast ceramic and metal scaffolds have different structural characteristics and overall porosities. Basic criticality results were compiled for the various models

  17. Awareness programs and change in taste-based caste prejudice.

    Science.gov (United States)

    Banerjee, Ritwik; Datta Gupta, Nabanita

    2015-01-01

    Becker's theory of taste-based discrimination predicts that relative employment of the discriminated social group will improve if there is a decrease in the level of prejudice for the marginally discriminating employer. In this paper we experimentally test this prediction offered by Garry Becker in his seminal work on taste based discrimination, in the context of caste in India, with management students (potential employers in the near future) as subjects. First, we measure caste prejudice and show that awareness through a TV social program reduces implicit prejudice against the lower caste and the reduction is sustained over time. Second, we find that the treatment reduces the prejudice levels of those in the left tail of the prejudice distribution--the group which can potentially affect real outcomes as predicted by the theory. And finally, a larger share of the treatment group subjects exhibit favorable opinion about reservation in jobs for the lower caste.

  18. Shear capacity of high-strength concrete beams with their point of inflection within the shear span

    OpenAIRE

    Islam, MS; Pam, HJ; Kwan, AKH

    1998-01-01

    The shear strength of concrete does not increase in proportion with the concrete grade. Thus, when high-strength concrete is used in place of normal-strength concrete, the shear capacity of the structure could become critical. In the study presented, the effect of concrete strength on the shear capacity of concrete beams was investigated. As previous research on normal-strength concrete beams has shown that the presence of an inflection point within the shear span can significantly influence ...

  19. SPRAY CASTING

    OpenAIRE

    SALAMCI, Elmas

    2010-01-01

    ABSTRACT This paper is designed to provide a basic review of spray casting. A brief overview of the historical development of spray  casting and the description of plant and equipment have been given. Following metallurgical characteristics of spray formed alloys, process parameters and solidification mechanism of spray deposition have been discussed in detail. Finally, microstructure and mechanical properties of the selected spray cast Al-Zn-Mg-Cu alloys have been presented and compared...

  20. Residual stress in spin-cast polyurethane thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hong; Zhang, Li, E-mail: lizhang@mae.cuhk.edu.hk [Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin N.T., Hong Kong (China); Chow Yuk Ho Technology Centre for Innovative Medicine, The Chinese University of Hong Kong, Shatin N.T., Hong Kong (China)

    2015-01-19

    Residual stress is inevitable during spin-casting. Herein, we report a straightforward method to evaluate the residual stress in as-cast polyurethane thin films using area shrinkage measurement of films in floating state, which shows that the residual stress is independent of radial location on the substrate and decreased with decreasing film thickness below a critical value. We demonstrate that the residual stress is developed due to the solvent evaporation after vitrification during spin-casting and the polymer chains in thin films may undergo vitrification at an increased concentration. The buildup of residual stress in spin-cast polymer films provides an insight into the size effects on the nature of polymer thin films.

  1. Managament quality of tools in the planned housing casting

    Directory of Open Access Journals (Sweden)

    Jaworski J.

    2007-01-01

    Full Text Available The Kaizen method of housing casting designing was presented in the paper. Algorithm making possibility of identification of tools limiting efficienty of tooling process was formulated. The system of tool management consisting of various was shown.

  2. Application of Fly Ash from Solid Fuel Combustion in Concrete

    OpenAIRE

    Pedersen, Kim Hougaard; Dam-Johansen, Kim; Jensen, Anker Degn

    2008-01-01

    Application of Fly Ash from Solid Fuel Combustion in Concrete Kim H. Pedersen Abstract Industrial utilization of fly ash from pulverized coal combustion plays an important role in environmentally clean and cost effective power generation. Today, the primary market for fly ash utilization is as pozzolanic additive in the production of concrete. However, the residual carbon in fly ash can adsorb the air entraining admixtures (AEAs) added to enhance air entrainment in concrete in order to increa...

  3. Safety training: places available in September 2014

    CERN Multimedia

    HSE Unit

    2014-01-01

    There are places available in the forthcoming Safety courses. For updates and registrations, please refer to the Safety Training Catalogue (see here).   Please note that there are 7 places left on the “Territorial Safety Officer (TSO) – Initial” course on September 23-25, 2014 (in French).

  4. Wear Property of Cast Steel Wheel Material in Rail Truck

    Institute of Scientific and Technical Information of China (English)

    MI Guo-fa; LIU Yan-lei; ZHANG Bin; FU Xiu-qin; ZHANG Hong; SONG Guo-xiang

    2009-01-01

    Wear property of material plays a key role in the service time of workpiece.A major objective in the development of new wheel materials is to improve the wear performance.The wear property of B and B+ grade cast steel materials was reported.The results showed that B+ grade cast steel material exhibited better wear property than the B grade material.Carbon content related to the hardness match was the principal factor affecting the wear properties.

  5. A study of interfacial heat transfer and process parameters in squeeze casting and low pressure permanent mold casting

    Science.gov (United States)

    Krishna, Prasad

    2001-08-01

    With the emerging demand for energy efficient and environment-friendly automobiles, cast aluminum alloys are increasingly being used in their manufacture. In this context, two permanent mold casting processes, namely, Squeeze Cast Permanent Mold and Low Pressure Permanent Mold (LPPM) have become very popular in the production of high integrity shape-cast aluminum components. However, many industries are yet to benefit from the full potential of these processes due to limited understanding of the effect of process parameters on casting quality and the necessary boundary conditions for computer modeling and simulation so as to minimize costly field trials. This dissertation attempts to address some of these concerns facing today's foundry industry. An experimental investigation of the Indirect Squeeze Casting Process was conducted by pouring molten Al-7Si-0.3Mg (A356) alloy into a specially designed and instrumented mold, mounted on a horizontal clamped-vertical shot squeeze caster (HVSC). Temperature measurements close to the metal/mold interface were made and compared with the results of the numerical simulation of heat flow during solidification and cooling of castings. The Heat Transfer Coefficient (HTC), a critical parameter essential for any solidification simulation, was estimated based on the simulation that gave the best fit to the experimental temperature data. During the solidification process, the HTC is relatively uniform over the entire casting and on reaching a critical solidification pressure, the HTC is close to 4500 W/m2 K. The work has also provided a correlation of Secondary Dendrite Arm Spacing (SDAS) with cooling rate for a modified A356 alloy. Low Pressure Permanent Mold Casting experiments were conducted by pouring a nearly identical aluminum alloy into an instrumented, coated mold mounted on a low pressure casting machine. The pressure levels, along with the time required to achieve complete filling, were microprocessor controlled in the

  6. The Next Generation Ecological Self Compacting Concrete with Glass Waste Powder as a Cement Component in Concrete and Recycled Concrete Aggregates

    OpenAIRE

    Kara, P

    2013-01-01

    In the present study the performance characteristics (workability, compressive strength, frost resistance, permeability and temperature of hydration) of the ecological self compacting concrete with reduced cement content and with the next generation recycled concrete aggregates which are obtained from crashed concrete specimens with cement substitution at level of 30% with waste glass powder were investigated. Waste glass as powder ground to certain fineness accelerates beneficial chemical re...

  7. Application of 3D stereoscopic visualization technology in casting aspect

    Institute of Scientific and Technical Information of China (English)

    Kang Jinwu; Zhang Xiaopeng; Zhang Chi; Liu Baicheng

    2014-01-01

    3D stereoscopic visualization technology is coming into more and more common use in the field of entertainment, and this technology is also beginning to cut a striking ifgure in casting industry and scientiifc research. The history, fundamental principle, and devices of 3D stereoscopic visualization technology are reviewed in this paper. The authors’ research achievements on the 3D stereoscopic visualization technology in the modeling and simulation of the casting process are presented. This technology can be used for the observation of complex 3D solid models of castings and the simulated results of solidiifcation processes such as temperature, lfuid lfow, displacement, stress strain and microstructure, as wel as the predicted defects such as shrinkage/porosity, cracks, and deformation. It can also be used for other areas relating to 3D models, such as assembling of dies, cores, etc. Several cases are given to compare the illustration of simulated results by traditional images and red-blue 3D stereoscopic images. The spatial shape is observed better by the new method. The prospect of 3D stereoscopic visualization in the casting aspect is discussed as wel. The need for aided-viewing devices is stil the most prominent problem of 3D stereoscopic visualization technology. However, 3D stereoscopic visualization represents the tendency of visualization technology in the future; and as the problem is solved in the years ahead, great breakthroughs wil certainly be made for its application in casting design and modeling and simulation of the casting processes.

  8. Stereology of carbide phase in modified hypereutectic chromium cast iron

    Directory of Open Access Journals (Sweden)

    J. Suchoń

    2010-04-01

    Full Text Available In paper are presented results of studies of carbide phase stereology modified hypereutectic wear resistance chromium cast iron which contains carbon about 3,5% and chromium about 25%. Three substances were applied to the modification: boron carbide (B4C, ferroniobium (FeNb and mixture of ferroniobium and rare-earth (RE. The measurements of geometrical features of carbides were conducted on microsection taken from castings wich were cooled with various velocities.

  9. Stereology of carbide phase in modified hypereutectic chromium cast iron

    OpenAIRE

    J. Suchoń; A. Studnicki; M. Przybył

    2010-01-01

    In paper are presented results of studies of carbide phase stereology modified hypereutectic wear resistance chromium cast iron which contains carbon about 3,5% and chromium about 25%. Three substances were applied to the modification: boron carbide (B4C), ferroniobium (FeNb) and mixture of ferroniobium and rare-earth (RE). The measurements of geometrical features of carbides were conducted on microsection taken from castings wich were cooled with various velocities.

  10. Caste, Class and the Love-Marriage: Social Change in India

    Science.gov (United States)

    Corwin, Lauren A.

    1977-01-01

    The present study of a small town in rural West Bengal, India, reveals a number of "love-marriages" involving individuals from castes of distinctly different ranks in the local caste hierarchy. Despite the prevailing rule of caste endogamy, inter-caste couples appear to face little difficulty. (Author)

  11. Quality of concrete : one example in the north of Portugal

    OpenAIRE

    Cunha, P. J.; Aguiar, J. L. Barroso de; De Oliveira, Pedro; Camões, Aires

    2010-01-01

    The non-quality and non-conformity of concrete, simulates the development of pathologies into the structure and consequently in coatings and masonry. So an early degradation of the buildings could be reached. The objectives of this study were he characterization of the procedures adopted for the production concrete n some works in the north of Portugal, determining he strength class required in the project. At this point, we performed the evaluation of the compressive resistance f concrete n ...

  12. Optimization of Micro Silica in Light Weight Lika Concrete

    OpenAIRE

    Alireza M.G. Roshan; Mohammad B. Hosseinian; Hossein Khalilpasha; Reza Amirpour

    2010-01-01

    Problem statement: In this article, special kind of light weight aggregate named lika had been studied. Approach: The aim of this research was first, to achieve the best mix design of light weight concrete which could be in light weight concrete category and second, by applying the first part gain the main reason of this research which was finding the optimized amount of Micro Silica in a light weight lika concrete. Results: Experimental results had been compared with theoretical viewpoints t...

  13. STUDY ON STRENGTH OF BACTERIAL CONCRETE IN BACILLUS MEGATERIUM

    OpenAIRE

    Deepika.B*, C.Savinth Kumar

    2016-01-01

    Concrete a strong, durable material composed of cement, aggregate and water is the most used building material in the world. Concrete has an ultimate load bearing capacity under compression but the material is weak in tension. The steel reinforced bars take the load when the concrete cracks in tension. To increase the strength and durability of the structure either crack that are formed should be repaired conventionally using epoxy injection or latex treatment or by providing extra reinforcem...

  14. 现浇楼板对RC框架梁抗弯承载力的增强作用%Study on the Effect of Over-strength Caused by Casting Slab on the Moment Bearing Capability of Beam for Reinforced Concrete Frame Structures

    Institute of Scientific and Technical Information of China (English)

    李永梅; 郭磊; 周锡元

    2012-01-01

    By analyzing the failure model of various reinforced concrete frame structures in earthquake, it shows that the failure mechanism of strong column and weak beam expected could not achieve for a lot of casting reinforced concrete frame structures. Based on the effect of casting slab on the moment bearing capability of beam in reinforced concrete frame structures, the mechanism on the effect of the over-strength caused by casting slab on the negative moment bearing capability of beam end is studied. By analyzing an actual example according to design codes, it shows that although the increasing coefficients of moment of column end are enhanced in GB 50011-2010 code for seismic design of buildings, GB 50010-2010 code for design of concrete structures, and JG J3-2010 technical specification for concrete structures of tall building and higher ratios of reinforcement were used, the mechanism of strong column and weak beam cannot be surely achieved. In conclusion, some suggestions for structural design are given for reinforced concrete frame structures, such as how to strengthen bending moments at the ends of column, to calculate real negative bending moments at the ends of beam and so on.%震害分析表明,大量的现浇钢筋混凝土框架结构并未实现设计规范所要求的“强柱弱梁”梁铰破坏机制.总结国内外研究现状,研究楼板作用(楼板内钢筋)对支座节点处的实际负弯矩增强作用机理;并基于设计规范中的规定,通过实例计算分析,表明尽管GB 50011-2010规范、GB 50010-2010规范和JGJ3-2010规程进一步提高了柱端弯矩增大系数,但在板具有较高配筋率时,仍不能完全保证“强柱弱梁”的实现.最后给出了增强柱端弯矩、以及梁端实际负弯矩计算和配置等方面的设计建议.

  15. Durability Indicators in High Absorption Recycled Aggregate Concrete

    OpenAIRE

    Jiménez, Luis F.; Moreno, Eric I.

    2015-01-01

    The use of recycled aggregates in structural concrete production has the inconvenience of increasing the fluid transport properties, such as porosity, sorptivity, and permeability, which reduces the resistance against penetration of environmental loads such as carbon dioxide and chloride ion. In this paper, behavior of ten concrete mixtures with different percentages of coarse aggregate replacement was studied. The recycled material was recovered by crushing of concrete rubble and had high ab...

  16. Sustainable concrete in Asia: Approaches and barriers considering regional context

    OpenAIRE

    Henry, Michael; Kato, Yoshitaka

    2014-01-01

    Asia is home to a diversity of socio-economic and environmental conditions which directly affect concrete-related manufacturing and construction. The implementation of sustainable concrete in Asian countries is thus highly dependent on their regional conditions, but the regional context of sustainable concrete needs to be understood in order to connect generalized strategies with actual implementation. This paper summarizes the results and key findings from previous qualitative investigations...

  17. Wider application of additions in self-compacting concrete

    OpenAIRE

    Liu, M.

    2009-01-01

    Compared to normally vibrated concrete (NVC), self-compacting concrete (SCC) possesses enhanced qualities and improves productivity and working conditions due to the elimination of compaction. SCC generally has a higher powder content than NVC and thus it is necessary to replace some of the cement by additions to achieve an economical and durable concrete. The established benefits of using low volumes of fly ash in SCC, high volumes of fly ash in NVC and the search for uses ...

  18. Experimental Investigation of Use of Microsilica in Self Compacting Concrete

    OpenAIRE

    Mr.Ashok P. Kalbande; Prof. R.V.R.K. Prasad

    2012-01-01

    This paper is described Project in detail and presents laboratory observation. Microsilica is used as a 10% replacement of cement by weight. Various test were conducted on fine aggregate & coarse aggregate, to determine specific gravity, bulk density, fineness modulus of aggregate, concrete mix proportion design using this parameter..For conventional concrete water cement ratio of 0.4 and for microsilica concrete is increased water contain about 20liter/m3. Water demand increases in ...

  19. Influence of cracks on chloride penetration in concrete

    OpenAIRE

    Audenaert, K.; Schutter, G. de; MARSAVINA, L

    2009-01-01

    Chloride initiated reinforcement corrosion is the main durability problem for concrete structures in a marine environment. If the chlorides reach the reinforcement steel, it will depassivate and start to corrode in presence of air and water. Since the corrosion products have a larger volume than the initial products, concrete stresses are induced, leading to spalling and degradation of the concrete structures. If cracks, caused by early drying, thermal effects, shrinkage movements or overstre...

  20. Horizons of place in Utzon's Bayview Project

    DEFF Research Database (Denmark)

    Andersen, Michael Asgaard

    In this paper, the horizons of place are discussed in relation to the work of danish architect Jørn Utzon. As one of the most significant personalities of nordic architecture in the second half of the twentieth century, Utzon created a body of work that deals with place in profound and unexpected...... understandings of his work. In doing so, the paper aims at approaching architecture and phenomenology through tensional relationships in the places of Utzon's Bayview project.......In this paper, the horizons of place are discussed in relation to the work of danish architect Jørn Utzon. As one of the most significant personalities of nordic architecture in the second half of the twentieth century, Utzon created a body of work that deals with place in profound and unexpected...... ways. While previous scholarship by Christian Norberg-Schulz and others has focused on regional aspects, or regional versus international aspects, this paper understands places in Utzon's Bayview project in a broaderb sense. Considering this project within contemporary place notions, opens for new...

  1. Investigation on the Potentials of Cupola Furnace Slag in Concrete

    Directory of Open Access Journals (Sweden)

    Stephen Adeyemi Alabi

    2013-12-01

    Full Text Available The compressive strength of the concrete designed using blast cupola furnace slag and granulated cupola slag as a coarse aggregate and partial replacement for cement was investigated. A series of experimental studies were conducted involve concrete production in two stages. The first stage comprised of normal aggregate concrete (NAC produced with normal aggregates and 100% ordinary Portland cement (OPC. Meanwhile, the second stage involved production of concrete comprising of cupola furnace slag an aggregates with 100% ordinary Portland cement (OPC and subsequently with 2%, 4%, 6%, 8% and 10% cementitious replacement with granulated cupola furnace slag that had been grounded and milled to less than 75 µm diameter. The outcomes of compressive strength test conducted on the slag aggregate concrete (SAC with and without granulated slag cementitious replacement were satisfactory compared to normal aggregate concretes (NAC.

  2. Eventful places in the 2011 movements

    DEFF Research Database (Denmark)

    Risager, Bjarke Skærlund

    Inspired by the Occupy movement, the Egyptian revolutionaries and other of the 2011 social movements, this paper investigates the relationship between social movement and place. Drawing on first-hand accounts from these movements, I argue that the relationship between movement and place...... is dialectical and mutually constitutive: the physical and symbolic characteristics of place influence the formation of the movement and its actions while the latter re-creates the place. This is a corrective to a dominant approach in social movement studies to see movements as a ‘dependent variable......’ that is to be explained (della Porta 2008) instead of a political subject with the ability to affect itself and society; and a corrective to the growing body of literature on the geographies of social movements that often has a too static and state-centred approach. Using John Agnew’s (1987) conceptualisation of place...

  3. Possibilites for Structural Improvements in the Design of Concrete Bridges

    OpenAIRE

    Spasojevic, Ana

    2006-01-01

    This paper presents the concept and the current state of a research investigating possibilities for further evolutions in medium span concrete road bridges. The main parameters of the study are the structural shape, the type of materials used and their disposition. The study will provide an optimisation of the design of various systems of concrete bridges, with the perspective of introducing new advanced cementitious materials, such as ultra high performance fibre reinforced concrete, UHPFC. ...

  4. New Findings in Hydrogen Sulfide Related Corrosion of Concrete Sewers

    DEFF Research Database (Denmark)

    Nielsen, Asbjørn Haaning; Jensen, Henriette Stokbro; Hvitved-Jacobsen, Thorkild;

    2009-01-01

    main. H2S related concrete corrosion and odor is often observed at such locations. The experiments showed that the rate of H2S oxidation was significantly faster on concrete pipe surfaces than on plastic pipe surfaces. Steady state calculations based on the kinetic data demonstrated that the gas phase......, the paper demonstrates how the kinetic data can be used for prediction of concrete corrosion in real sewer systems based on H2S measurements from a conventional gas detector....

  5. Computational modelling of chloride ion transport in reinforced concrete

    OpenAIRE

    Meijers, S.J.H.; Bijen, J.M.J.M.; De Borst, R.; Fraaij, A.L.A.

    2001-01-01

    Exposure to a saline environment is a major threat with respect to the durability of reinforced concrete structures. The chloride ions, which are present in seawater and de-icing salts, are able to penetrate the concrete up to the depth of the reinforcement. They can eventually trigger a pitting corrosion process. The assessment of a corrosion-free service life of concrete structures is of paramount economic interest. However, the modelling of the ingress of chloride ions is complicated due t...

  6. In-place HEPA filter penetration test

    Energy Technology Data Exchange (ETDEWEB)

    Bergman, W.; Wilson, K.; Elliott, J. [Lawrence Livermore National Lab., CA (United States)] [and others

    1997-08-01

    We have demonstrated the feasibility of conducting penetration tests on high efficiency particulate air (HEPA) filters as installed in nuclear ventilation systems. The in-place penetration test, which is designed to yield equivalent penetration measurements as the standard DOP efficiency test, is based on measuring the aerosol penetration of the filter installation as a function of particle size using a portable laser particle counter. This in-place penetration test is compared to the current in-place leak test using light scattering photometers for single HEPA filter installations and for HEPA filter plenums using the shroud method. Test results show the in-place penetration test is more sensitive than the in-place leak test, has a similar operating procedure, but takes longer to conduct. Additional tests are required to confirm that the in-place penetration test yields identical results as the standard dioctyl phthalate (DOP) penetration test for HEPA filters with controlled leaks in the filter and gasket and duct by-pass leaks. Further development of the procedure is also required to reduce the test time before the in-place penetration test is practical. 14 refs., 14 figs., 3 tabs.

  7. Corrosion of Steel in Concrete, Part I – Mechanisms

    DEFF Research Database (Denmark)

    Küter, André; Møller, Per; Geiker, Mette Rica

    2006-01-01

    prematurely. Reinforcement corrosion is identified to be the foremost cause of deterioration. Steel in concrete is normally protected by a passive layer due the high alkalinity of the concrete pore solution; corrosion is initiated by neutralization through atmospheric carbon dioxide and by ingress...... of depassivation ions, especially chloride ions. The background and consequences of deterioration of reinforced concrete structures caused by steel corrosion are summarized. Selected corrosion mechanisms postulated in the literature are briefly discussed and related to observations. The key factors controlling...... initiation and propagation of corrosion of steel in concrete are outlined....

  8. Damage model of fresh concrete in sulphate environment

    Institute of Scientific and Technical Information of China (English)

    张敬书; 张银华; 冯立平; 金德保; 汪朝成; 董庆友

    2015-01-01

    A model of damage to fresh concrete in a corrosive sulphate environment was formulated to investigate how and why the strength of corroded concrete changes over time. First, a corroded concrete block was divided into three regions:an expanded and dense region;a crack-development region;and a noncorroded region. Second, based on the thickness of the surface corrosion layer and the rate of loss of compressive strength of the corroding region, a computational model of the concrete blocks’ corrosion-resistance coefficient of compressive strength in a sulphate environment was generated. Third, experimental tests of the corrosion of concrete were conducted by immersing specimens in a corrosive medium for 270 d. A comparison of the experimental results with the computational formulae shows that the calculation results and test results are in good agreement. A parameter analysis reveals that the corrosion reaction plays a major role in the corrosion of fresh concrete containing ordinary Portland cement, but the diffusion of the corrosion medium plays a major role in the corrosion of concrete mixtures containing fly ash and sulphate-resistant cement. Fresh concrete with a high water-to-cement ratio shows high performance during the whole experiment process whereas fresh concrete with a low water-to-cement ratio shows poor performance during the late experiment period.

  9. Utilisation of iron ore tailings as aggregates in concrete

    Directory of Open Access Journals (Sweden)

    Francis Atta Kuranchie

    2015-12-01

    Full Text Available Sustainable handling of iron ore tailings is of prime concern to all stakeholders who are into iron ore mining. This study seeks to add value to the tailings by utilising them as a replacement for aggregates in concrete. A concrete mix of grade 40 MPa was prepared in the laboratory with water–cement ratio of 0.5. The concrete were cured for 1, 2, 3, 7, 14 and 28 days. The properties of the concrete such as workability, durability, density, compressive strength and indirect tensile strength were tested. A controlled mix of concrete was also prepared in similar way using conventional materials and the results were compared with the tailings concrete. It was found that the iron ore tailings may be utilised for complete replacement for conventional aggregates in concrete. The iron ore tailings aggregates concrete exhibited a good mechanical strength and even in the case of compressive strength, there was an improvement of 11.56% over conventional aggregates concrete. The indirect tensile strength did not improve against the control mix due high content of fines in the tailings aggregates but showed 4.8% improvement compared with the previous study where the conventional fine aggregates was partially replaced by 20% with iron ore tailings.

  10. Optimization of casting defects analysis with supply chain in cast iron foundry process

    Directory of Open Access Journals (Sweden)

    C. Narayanaswamy

    2016-10-01

    Full Text Available Some of the foundries are in need of meeting production targets and due to the urgency they ignore the rejections. The objective of this paper is to analyze the various defects, [1] from molding process in a cast iron foundry. The Failure Mode Effects Analysis (FMEA in quality control [2-6] with suitable supply chain for mold making process considering rejection rates are identified and analyzed in terms of Risk Priority Number (RPN to prioritize the attention for each of the problem. The optimum levels of selected parameters [7] are obtained in this analysis.

  11. Preferred orientation of ettringite in concrete fractures

    KAUST Repository

    Wenk, Hans-Rudolf

    2009-05-15

    Sulfate attack and the accompanying crystallization of fibrous ettringite [Ca6Al2(OH)12(SO4) 3·26H2O] cause cracking and loss of strength in concrete structures. Hard synchrotron X-ray microdiffraction is used to quantify the orientation distribution of ettringite crystals. Diffraction images are analyzed using the Rietveld method to obtain information on textures. The analysis reveals that the c axes of the trigonal crystallites are preferentially oriented perpendicular to the fracture surfaces. By averaging single-crystal elastic properties over the orientation distribution, it is possible to estimate the elastic anisotropy of ettringite aggregates. © 2009 International Union of Crystallography.

  12. Interferences in Prompt γ Analysis of corrosive contaminants in concrete

    Science.gov (United States)

    Naqvi, A. A.; Nagadi, M. M.; Al-Amoudi, O. S. B.

    2006-12-01

    An accelerator-based Prompt Gamma Neutron Activation Analysis (PGNAA) setup has been developed to measure the concentration of corrosive chloride and sulfate contaminants in concrete. The Minimum Detectable Concentration (MDC) limit of chlorine and sulfur in the concrete depends upon the γ-ray used for elemental analysis. For more interfering γ-rays, the MDC limit is higher than that for less interfering γ-rays. The MDC limit of sulfur in concrete measured for the KFUPM PGNAA setup was calculated to be 0.60±0.19 wt%. The MDC limit is equal to the upper limit of sulfur concentration in concrete set by the British Standards. The MDC limit of chlorine in concrete for the KFUPM PGNAA setup, which was calculated for less interfering 1.165 MeV γ-rays, was found to be 0.075±0.025 wt%. The lower limits of the MDC of chlorine in concrete was 73% higher than the limit set by American Concrete Institute. The limit of the MDC can be improved to the desired standard by increasing the intensity of neutron source. For moreinterfering 5.715 and 6.110 MeV chlorine γ-rays the MDC limit was found to be 2-3 times larger than that of 1.165 MeV γ-rays. When normalized to the same intensity of the neutron source, the MDC limits of chlorine and sulfur in concrete from the KFUPM PGNAA setup are better than MDC limits of chlorine in concrete obtained with the 241Am-Be source-based PGNAA setup. This study has shown that an accelerator-based PGNAA setup can be used in chlorine and sulfur analysis of concrete samples.

  13. Teaching students in place: the languages of third space learning

    Science.gov (United States)

    Morawski, Cynthia M.

    2016-07-01

    With a perceptive eye cast on geoscience pedagogy for students labeled as disabled, Martinez-Álvarez makes important contributions to the existing conversation on placed-based learning. It is in our local backyards, from the corner basketball court, to the mud bank of a city lake, to the adjacent field where rocky outcrops spill down to a forgotten farmer's field, that we find rich working material for connecting self and community, moving students' out-of-school experiences that feature their cultural and linguistic knowledge, from misconceptions to "alternative conceptions." Informed by her insights regarding the learning of students whose literacy does not match conventional classroom practice, geoscience learning in the place of third space can act as a model of meaning making across the entire curriculum. In the pages that follow, I transact, both aesthetically and efferently, with Martinez-Álvarez's text as she presents her research on special ways of learning in placed-based geoscience explorations with bilingual children experiencing disabilities.

  14. Size Effect for Normal Strength Concrete in Uniaxial Tension

    Institute of Scientific and Technical Information of China (English)

    李庆斌; 尹玉先

    2004-01-01

    This paper presents a new size effect model for normal strength concrete subjected to uniaxial tension. The model is based on two extremes, sand cement paste in uniaxial tension and a sand-cement-paste/rock interface in uniaxial tension. Uniaxial tension tests with normal strength concrete measuring the tensile strength of normal strength concrete specimens with different geometrical shapes and different ratios of the aggregate size to the characteristic dimension of the concrete specimen show a significant size effect. The theoretical size effect law prediction agrees well with the experimental data.

  15. Utilisation of iron ore tailings as aggregates in concrete

    OpenAIRE

    Francis Atta Kuranchie; Sanjay Kumar Shukla; Daryoush Habibi; Alireza Mohyeddin

    2015-01-01

    Sustainable handling of iron ore tailings is of prime concern to all stakeholders who are into iron ore mining. This study seeks to add value to the tailings by utilising them as a replacement for aggregates in concrete. A concrete mix of grade 40 MPa was prepared in the laboratory with water–cement ratio of 0.5. The concrete were cured for 1, 2, 3, 7, 14 and 28 days. The properties of the concrete such as workability, durability, density, compressive strength and indirect tensile strength we...

  16. Place in Pacific Islands Climate Education

    Science.gov (United States)

    Barros, C.; Koh, M. W.

    2015-12-01

    Understanding place, including both the environment and its people, is essential to understanding our climate, climate change, and its impacts. For us to develop a sense of our place, we need to engage in multiple ways of learning: observation, experimentation, and opportunities to apply new knowledge (Orr, 1992). This approach allows us to access different sources of knowledge and then create local solutions for local issues. It is especially powerful when we rely on experts and elders in our own community along with information from the global community.The Pacific islands Climate Education Partnership (PCEP) is a collaboration of partners—school systems, nongovernmental organizations, and government agencies—working to support learning and teaching about climate in the Pacific. Since 2009, PCEP partners have been working together to develop and implement classroom resources, curriculum standards, and teacher professional learning opportunities in which learners approach climate change and its impacts first through the lens of their own place. Such an approach to putting place central to teaching and learning about climate requires partnership and opportunities for learners to explore solutions for and with their communities. In this presentation, we will share the work unfolding in the Republic of the Marshall Islands (RMI) as one example of PCEP's approach to place-based climate education. Three weeklong K-12 teacher professional learning workshops took place during June-July 2015 in Majuro, RMI on learning gardens, climate science, and project-based learning. Each workshop was co-taught with local partners and supports educators in teaching climate-related curriculum standards through tasks that can foster sense of place through observation, experimentation, and application of new knowledge. Additionally, we will also share PCEP's next steps in place-based climate education, specifically around emerging conversations about the importance of highlighting

  17. Bond behavior between reinforcing steel and concrete under multiaxial loading conditions in concrete containments

    International Nuclear Information System (INIS)

    Important elements of the safety equipment of nuclear power plants are reinforced and prestressed concrete containments, which generally have been used as protective cover in pressurized-water and boiling-water reactors. For these structures, the leakage rate of hazardous products has to be limited to a maximum allowable rate. Therefore, the verification of integrity and leak tightness of containment structures is of high priority. In this study the deformation behavior of a modern prestressed concrete containment under increasing internal pressure was tested by means of a 1:4 scale model in the Sandia National Laboratories in the USA

  18. Application of microorganisms in concrete: a promising sustainable strategy to improve concrete durability.

    Science.gov (United States)

    Wang, Jianyun; Ersan, Yusuf Cagatay; Boon, Nico; De Belie, Nele

    2016-04-01

    The beneficial effect of microbially induced carbonate precipitation on building materials has been gradually disclosed in the last decade. After the first applications of on historical stones, promising results were obtained with the respect of improved durability. An extensive study then followed on the application of this environmentally friendly and compatible material on a currently widely used construction material, concrete. This review is focused on the discussion of the impact of the two main applications, bacterial surface treatment and bacteria based crack repair, on concrete durability. Special attention was paid to the choice of suitable bacteria and the metabolic pathway aiming at their functionality in concrete environment. Interactions between bacterial cells and cementitious matrix were also elaborated. Furthermore, recommendations to improve the effectiveness of bacterial treatment are provided. Limitations of current studies, updated applications and future application perspectives are shortly outlined.

  19. FEM Analysis of Physical Field in Level Rolling Process of Inversion Casting by ANSYS Program

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The strain physical field in level rolling process of inversion casting was analyzed by ANSYS program. Plastics train, stress and displacement were gained. The results show that only surfaces train takes place; the maximum stress exists in the geometrical deformation zone ; In the deformation transition zone and the part leaving the rollers, different stress exists. The rolling force estimated with ANSYS program corresponds to those measured.

  20. Experimental assessment of damping factors in concrete housing walls

    OpenAIRE

    Julián Carrillo; Sergio M. Alcocer; Giovanni González

    2012-01-01

    Thin walls having low concrete strength, minimum web steel ratios and web shear reinforcement made of welded wire meshes are commonly used in low-rise concrete housing. The damping factor commonly used for code-based dynamic analysis was evaluated based on seismic response measured during shake table tests of six low-rise concrete walls. The variables studied were the type of concrete (normal and lightweight), the web steel shear ratio (0.125% and 0.25%), the type of web shear reinforcement (...

  1. Chemical Agents: Facts about Sheltering in Place

    Science.gov (United States)

    ... have in your shelter room: First aid kit Flashlight, battery-powered radio, and extra batteries for both ... on the radio and on television emergency broadcast system if you need to shelter in place. What ...

  2. Geographic Place Names, Published in unknown, SWGRC.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Geographic Place Names dataset as of unknown. Data by this publisher are often provided in Geographic coordinate system; in a Not Sure projection; The extent...

  3. Electronic market places in the energy

    International Nuclear Information System (INIS)

    Electronic market places in the energy domain occurred at the end of the 90's in the US and have started to develop in Europe in the year 2000. About 60 platforms are registered today and this development can be explained by the advantages raised by such an infrastructure: simplification of purchase procedures, reduction of delays in the purchase decision, reduction of administrative costs etc.. However, today none of these electronic market places is profitable and several have closed down. On the other hand, this tool will certainly become necessary in the future and all energy actors are developing projects in this way. This study analyzes the electronic market places phenomenon in the energy domain using 10 market places examples with their key-factors of success. It draws out a complete status of the initiatives developed today and presents some scenarios of evolution. (J.S.)

  4. Study of carbon and silicon loss through oxidation in cast iron base metal using rotary furnace for melting

    Directory of Open Access Journals (Sweden)

    Sylvester Olanrewaju OMOLE

    2015-05-01

    Full Text Available The projection of loss of carbon and silicon through oxidation is uncertain phenomenon depending on the furnace used for melting, which affect the carbon equivalent value (CEV of cast iron produced. CEV enhances the fluidity of molten metal as well as having great effects on the mechanical properties of cast products. Study on the way elemental loss takes place during melting with rotary furnace will give idea of approach to minimize the loss. Therefore, the aim of this work is to study the magnitude of the elemental loss with rotary furnace and means to minimize the loss. 60kg of grey cast iron scrap was charged into rotary furnace of 100kg capacity after preheating the furnace for 40 minutes. Graphite and ferrosilicon was added to the charge in order to obtain a theoretical composition of not less than 4.0% carbon and 2.0% silicon. Charges in the furnace were heated to obtain molten metal which was tapped at 1400°C. Tapping was done for casting at three different times. The castings solidified in sand mould and allowed to cool to room temperature in the mould. Castings were denoted as sample 1, 2 and 3. Final compositions of each casting were analyzed with optical light emission spectrometer. Sample 1 has 2.95% carbon and 1.82% silicon. Sample 2 has 2.88% carbon and 1.70% silicon and sample 3 has 2.75% carbon and 1.63% silicon.

  5. How Concrete is Concrete

    Directory of Open Access Journals (Sweden)

    Koeno Gravemeijer

    2010-07-01

    Full Text Available If we want to make something concrete in mathematics education, we are inclined introduce, what we call, ‘manipulatives’, in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own, abstract, knowledge; in the latter, we try to find an example that the others will be familiar with. This article first looks at the tension between these two different ways of making things concrete. Next another role of manipulatives, will be discussed, namely that of means for scaffolding and communication. In this role, manipulatives may function as means of support in a process that aims at helping students to build on their own thinking while constructing more sophisticated mathematics

  6. Very heavy iron-punching concretes

    International Nuclear Information System (INIS)

    The present report deals with all the heavy iron-punching concretes, metallic wastes produced by the transformation industry. After a detailed description of the physical properties of metallic aggregates, a classification of heavy mortars is given, into three main categories: steel-shot grouts d = 5,3 - 6; steel-shot grouts mixed with a mineral d = 3,7 - 4,2; injection heavy grouts d = 3,5 - 4. The following chapter describes iron-punching concretes the most used in the atomic industry: iron-punching concretes mixed with cast-iron - iron-punching concretes mixed with magnetite; iron-punching concretes mixed with barite; iron-punching concretes mixed with limonite; iron-punching concretes mixed with boron. The compositions of these concretes are given together with their physical and mechanical characteristics. Numerous diagrams make it possible to find rapidly the proportions of the constituents of these concretes as a function of the required density. Technical advice and specifications are given in an appendix together with a bibliography of these heavy concretes. (author)

  7. EXPERIMENTAL STUDY ON EFFECT OF VARIOUS FACTORS ON COMPRESSIVE STRENGTH OF CONCRETE

    Directory of Open Access Journals (Sweden)

    Hanifi BİNİCİ

    2000-03-01

    Full Text Available In this study, the factors affecting at the compressive strength of the concrete were determined. According the result of the test, the quality of concrete, which was used, is very low. Cement, analysis of aggregates for concrete, compacting, mixing placing and curing of concrete, and the techniques of the production of concrete have effected by different ratio of the quality of concrete.

  8. Radionuclide Retention in Concrete Wasteforms - FY13

    Energy Technology Data Exchange (ETDEWEB)

    Snyder, Michelle MV; Golovich, Elizabeth C.; Wellman, Dawn M.; Crum, Jarrod V.; Lapierre, Robert; Dage, Denomy C.; Parker, Kent E.; Cordova, Elsa A.

    2013-10-15

    Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e., sorption or precipitation); the mechanism of contaminant release; the significance of contaminant release pathways; how wasteform performance is affected by the full range of environmental conditions within the disposal facility; the process of wasteform aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of wasteform aging on chemical, physical, and radiological properties; and the associated impact on contaminant release. This knowledge will enable accurate prediction of radionuclide fate when the wasteforms come in contact with groundwater. Data collected throughout the course of this work will be used to quantify the efficacy of concrete wasteforms, similar to those used in the disposal of low-level waste and mixed low-level waste, for the immobilization of key radionuclides (i.e., uranium, technetium, and iodine). Data collected will also be used to quantify the physical and chemical properties of the concrete affecting radionuclide retention.

  9. Yield improvement and defect reduction in steel casting

    Energy Technology Data Exchange (ETDEWEB)

    Kent Carlson

    2004-03-16

    This research project investigated yield improvement and defect reduction techniques in steel casting. Research and technology development was performed in the following three specific areas: (1) Feeding rules for high alloy steel castings; (2) Unconventional yield improvement and defect reduction techniques--(a) Riser pressurization; and (b) Filling with a tilting mold; and (3) Modeling of reoxidation inclusions during filling of steel castings. During the preparation of the proposal for this project, these areas were identified by the High Alloy Committee and Carbon and Low Alloy Committee of the Steel Founders' Society of America (SFSA) as having the highest research priority to the steel foundry industry. The research in each of the areas involved a combination of foundry experiments, modeling and simulation. Numerous SFSA member steel foundries participated in the project through casting trials and meetings. The technology resulting from this project will result in decreased scrap and rework, casting yield improvement, and higher quality steel castings produced with less iteration. This will result in considerable business benefits to steel foundries, primarily due to reduced energy and labor costs, increased capacity and productivity, reduced lead-time, and wider use and application of steel castings. As estimated using energy data provided by the DOE, the technology produced as a result of this project will result in an energy savings of 2.6 x 10{sup 12} BTU/year. This excludes the savings that were anticipated from the mold tilting research. In addition to the energy savings, and corresponding financial savings this implies, there are substantial environmental benefits as well. The results from each of the research areas listed above are summarized.

  10. Studies of detailed biofilm characterization on fly ash concrete in comparison with normal and superplasticizer concrete in seawater environments.

    Science.gov (United States)

    Vishwakarmaa, Vinita; George, R P; Ramachandran, D; Anandkumar, B; Mudalib, U Kamachi

    2014-01-01

    In cooling water systems, many concrete structures in the form of tanks, pillars and reservoirs that come in contact with aggressive seawater are being deteriorated by chemical and biological factors. The nuclear industry has decided to partially replace the Portland cement with appropriate pozzolans such as fly ash, which could densify the matrix and make the concrete impermeable. Three types of concrete mixes, viz., normal concrete (NC), concrete with fly ash and superplasticizer (FA) and concrete with only superplasticizer (SP) were fabricated for short- and long-term exposure studies and for screening out the better concrete in seawater environments. Biofilm characterization studies and microscopic studies showed excellent performance of FA concrete compared to the other two. Laboratory exposure studies in pure cultures of Thiobacillus thiooxidans and Fusarium oxysporum were demonstrated for the inhibition of microbial growth on fly ash. Epifluorescence and scanning electron microscopic studies supported the better performance of the FA specimen. Thus, the present study clearly showed that FA concrete is less prone to biofilm formation and biodeterioration. PMID:24600839

  11. Interaction of clay and concrete plugs - Plugging of 5 m deep hole KA1621G01 at Aespoe

    Energy Technology Data Exchange (ETDEWEB)

    Pusch, Roland [Drawrite AB, Lund (Sweden); Luleaa Technical Univ., Luleaa (Sweden); Ramqvist, Gunnar [Eltekno AB, Figeholm (Sweden)

    2011-11-15

    Sealing of deep boreholes in repository rock is planned to be made by installing dense smectite clay plugs where the rock is low-permeable and casting concrete where the holes intersect water-bearing fracture zones. Such zones have to be stabilized before sealing starts because fragments of rock can otherwise fall off and make it difficult to bring equipment for concrete casting and clay plug units down. These parts of the holes are filled with concrete and clay plugs are then inserted up to the nearest fracture zone where concrete is filled to the required level etc. The role of the concrete in the hole and in the closest part of the surrounding fracture zone is to provide stable parts that are sufficiently fine-porous to prevent clay particles from contacting clay plugs to migrate into the fractures and be lost by erosion. While the larger parts of long clay plugs are believed to stay largely intact chemically for hundreds of thousands of years, the parts adjacent to concrete plugs may undergo changes and so can the concrete plugs themselves. The objective of the presently reported project was to identify the detailed processes and quantify associated changes in physical properties by investigating samples of clay and concrete from a 2.5 m long plug of clay over which an equally long concrete plug had been cast and left to rest for 3 years. The outcome of the investigations was that significant chemically induced changes in mineralogy and physical performance had occurred within a few centimetres distance from the clay/concrete contact but that virtually no changes had taken place at larger distance. A comprehensive laboratory study including X-ray diffraction (XRD), X-ray fluorescence (XRF) and electron microscopy study (SEM and TEM) on the sample material was performed including also dual beam (combined ion and electron) microscopy. It was found that the clay had infiltrated the contacting concrete plug after filling of the borehole since clay was detected both

  12. Automatic inspection of surface defects in die castings after machining

    Directory of Open Access Journals (Sweden)

    S. J. Świłło

    2011-07-01

    Full Text Available A new camera based machine vision system for the automatic inspection of surface defects in aluminum die casting was developed by the authors. The problem of surface defects in aluminum die casting is widespread throughout the foundry industry and their detection is of paramount importance in maintaining product quality. The casting surfaces are the most highly loaded regions of materials and components. Mechanical and thermal loads as well as corrosion or irradiation attacks are directed primarily at the surface of the castings. Depending on part design and processing techniques, castings may develop surface discontinuities such as cracks or tears, inclusions due to chemical reactions or foreign material in the molten metal, and pores that greatly influence the material ability to withstand these loads. Surface defects may act as a stress concentrator initiating a fracture point. If a pressure is applied in this area, the casting can fracture. The human visual system is well adapted to perform in areas of variety and change; the visual inspection processes, on the other hand, require observing the same type of image repeatedly to detect anomalies. Slow, expensive, erratic inspection usually is the result. Computer based visual inspection provides a viable alternative to human inspectors. Developed by authors machine vision system uses an image processing algorithm based on modified Laplacian of Gaussian edge detection method to detect defects with different sizes and shapes. The defect inspection algorithm consists of three parameters. One is a parameter of defects sensitivity, the second parameter is a threshold level and the third parameter is to identify the detected defects size and shape. The machine vision system has been successfully tested for the different types of defects on the surface of castings.

  13. Market Design in Chinese Market Places

    OpenAIRE

    Krug, Barbara; Hendrischke, Hans

    2012-01-01

    textabstractThe market design (MD) approach to institutional analysis provides the analytical tools to evaluate endogenous institution building in local market places irrespective of the institutional setting of the national economy. Implicit in this analysis of endogenous institution building at the market place level is the recognition of institutional diversity, which none of the conventional forms of institutional analysis can provide. We extend the MD approach from its original game theo...

  14. Use of waste ash from palm oil industry in concrete.

    Science.gov (United States)

    Tangchirapat, Weerachart; Saeting, Tirasit; Jaturapitakkul, Chai; Kiattikomol, Kraiwood; Siripanichgorn, Anek

    2007-01-01

    Palm oil fuel ash (POFA), a by-product from the palm oil industry, is disposed of as waste in landfills. In this study, POFA was utilized as a pozzolan in concrete. The original size POFA (termed OP) was ground until the median particle sizes were 15.9 microm (termed MP) and 7.4 microm (termed SP). Portland cement Type I was replaced by OP, MP, and SP of 10%, 20%, 30%, and 40% by weight of binder. The properties of concrete, such as setting time, compressive strength, and expansion due to magnesium sulfate attack were investigated. The results revealed that the use of POFA in concretes caused delay in both initial and final setting times, depending on the fineness and degree of replacement of POFA. The compressive strength of concrete containing OP was much lower than that of Portland cement Type I concrete. Thus, OP is not suitable to be used as a pozzolanic material in concrete. However, the replacement of Portland cement Type I by 10% of MP and 20% of SP gave the compressive strengths of concrete at 90 days higher than that of concrete made from Portland cement Type I. After being immersed in 5% of magnesium sulfate solution for 364 days, the concrete bar mixed with 30% of SP had the same expansion level as that of the concrete bar made from Portland cement Type V. The above results suggest that ground POFA is an excellent pozzolanic material and can be used as a cement replacement in concrete. It is recommended that the optimum replacement levels of Portland cement Type I by MP and SP are 20% and 30%, respectively.

  15. The UK Casting Industry

    Institute of Scientific and Technical Information of China (English)

    Jincheng Liu

    2006-01-01

    The casting production in the UK in 2004 is presented and analysed. The UK casting industry has played an important role in world casting and manufacturing production. However recent years the rapid development of some developing countries has been shifting the casting production from the western industrialized countries including the UK. The UK casting industry and associated research and technology organizations, universities have been working together very hard to face the serious competition to make the UK casting industry have a sustainable future. The UK casting industry remains strong and plays an important role in world casting and manufacturing production.

  16. Study on Strength and Ultrasonic Velocity of Air-Entrained Concrete and Plain Concrete in Cold Environment

    Directory of Open Access Journals (Sweden)

    Huai-shuai Shang

    2014-01-01

    Full Text Available Nondestructive testing technology is essential in the quality inspection of repair, alteration, and renovation of the existing engineering, especially for concrete structure in severe environment. The objective of this work is to deal with the behavior of ultrasonic velocity and mechanical properties of plain concrete and air-entrained concrete subjected to freeze-thaw cycles (F-T-C. The ultrasonic velocity and mechanical properties (tensile strength, compressive strength, cubic compressive strength, and splitting strength of C30 air-entrained concrete and plain concrete with different water-cement ratio (water-cement ratio was 0.55, 0.45, and 0.50, resp. after F-T cycles were measured. The influences of F-T cycles on ultrasonic velocity and mechanical properties of C30 air-entrained concrete and plain concrete were analyzed. And the relationship between mechanical properties and ultrasonic velocity was established. The experimental results can be useful for the design of new concrete structure, maintenance and life prediction of existing concrete structure such as offshore platform and concrete dock wall.

  17. Corrosion of Steels in Steel Reinforced Concrete in Cassava Juice

    Science.gov (United States)

    Oluwadare, G. O.; Agbaje, O.

    The corrosion of two types of construction steels, ST60Mn and RST37-2♦, in a low cyanide concentration environment (cassava juice) and embedded in concrete had been studied. The ST60 Mn was found to be more corrosion resistant in both ordinary water and the cassava juice environment. The cyanide in cassava juice does not attack the steel but it provides an environment of lower pH around the steel in the concrete which leads to breakdown of the passivating film provided by hydroxyl ions from cement. Other factors such as the curing time of the concrete also affect the corrosion rates of the steel in the concrete. The corrosion rate of the steel directly exposed to cassava juice i.e., steel not embedded in concrete is about twice that in concrete. Long exposure of concrete structure to cassava processing effluent might result in deterioration of such structures. Careful attention should therefore be paid to disposal of cassava processing effluents, especially in a country like Nigeria where such processing is now on the increase.

  18. Numerical modelling and experimental assessment of concrete spalling in fire

    NARCIS (Netherlands)

    Shamalta, M.; Breunese, A.; Peelen, W.; Fellinger, J.

    2005-01-01

    In this paper, the phenomenon of spalling of concrete in fire has been studied using a numerical model. Spalling is the violent or non-violent breaking off of layers or pieces of concrete when it is exposed to high temperatures as experienced in fires. The types and mechanisms of spalling have been

  19. Strength Characteristics in the concrete with a Surface Enhancement Method

    International Nuclear Information System (INIS)

    In this study, dewatering performance-based sheets are attached to the inside of form in order to improve the durability of structures in N.P.P(nuclear power plants) through concrete surface enhancement. Then, the influence of dewatering sheet by removing the residual water inside the concrete analyzed on the strength

  20. Fracture Energy of High-Strength Concrete in Compression

    DEFF Research Database (Denmark)

    Dahl, H.; Brincker, Rune

    1989-01-01

    is essential for understanding the fracture mechanism of concrete in compression. In this paper a series of tests is reported, carried out for the purpose of studying the fracture mechanical properties of concrete in compression. Including the measurement and study of the descending branch, a new...

  1. Recrystallization microstructures and textures in AA 5052 continuous cast and direct chill cast aluminum alloy

    International Nuclear Information System (INIS)

    Commercially produced hot bands of AA 5052 continuous cast (CC) and direct chill (DC) cast aluminum alloys were cold rolled to (thickness) reductions of 70%, 80%, and 90% followed by annealing at different conditions. The recrystallization kinetics are found equivalent for both the CC and DC materials. Recrystallization microstructures are different between the CC and DC materials. Evolution of recrystallization texture in the CC and DC materials were investigated by using three-dimensional orientation distribution functions (ODFs) that were determined by X-ray diffraction. The recrystallization texture was correlated with cold rolling reduction (prior to annealing), annealing temperature, and annealing time. Results showed that the R {124} and cube {001} are dominant recrystallization texture components in both CC and DC materials. During annealing, the intensity and volume fraction of the cube component strongly depend on the prior cold rolling history. In contrast, the intensity and volume fraction of the R component remains almost constant regardless of the different cold rolling reductions prior to annealing. After complete recrystallization, the intensity and volume fraction of both R and cube components appear to be independent of the annealing temperature and annealing time

  2. Corrosion of Steel in Concrete: Prevention, Diagnosis, Repair

    NARCIS (Netherlands)

    Bertolini, L.; Elsener, B.; Redaelli, E.; Polder, R.

    2013-01-01

    Reinforced concrete has been developed and applied extensively in the 20th century. It combines the good compressive strength of concrete with the high tensile strength of steel and has proven to be successful in terms of structural performance and durability. However, there are instances of prematu

  3. Anchorage of Main Reinforcement in Lightweight Aggregate Concrete Beams

    DEFF Research Database (Denmark)

    Larsen, Henning

    1999-01-01

    The paper deals with the anchorage of reinforcement bars at end supports in beam component made of lightweight aggregate concrete with open structure.......The paper deals with the anchorage of reinforcement bars at end supports in beam component made of lightweight aggregate concrete with open structure....

  4. Concreteness Effects in the Processing of Chinese Words

    Science.gov (United States)

    Zhang, Qin; Guo, Chun-yan; Ding, Jin-hong; Wang, Zheng-yan

    2006-01-01

    The present study examined the relationship between word concreteness and word frequency using event-related potential (ERP) measurements during a lexical decision task. Potential effects of concreteness in the processing of verbs were also examined. ERPs were recorded from 119 scalp electrodes in 23 right-handed participants. The results showed…

  5. [Characteristic of Particulate Emissions from Concrete Batching in Beijing].

    Science.gov (United States)

    Xue, Yi-feng; Zhou, Zhen; Zhong, Lian-hong; Yan, Jing; Qu, Song; Huang, Yu-hu; Tian, He- zhong; Pan, Tao

    2016-01-15

    With the economic development and population growth in Beijing, there is a strong need for construction and housing, which leads to the increase of the construction areas. Meanwhile, as a local provided material, the production of concrete has been raised. In the process of concrete production by concrete batching, there are numerous particulates emitted, which have large effect on the atmospheric environment, however, systematic study about the tempo-spatial characteristics of pollutant emission from concrete batching is still rare. In this study, we estimated the emission of particulates from concrete batching from 1991 to 2012 using emission factor method, analyzed the tempo-spatial characteristics of pollutant emission, established the uncertainty range by adopting Monte-Carlo method, and predicted the future emission in 2020 based on the relative environmental and economical policies. The results showed that: (1) the emissions of particulates from concrete batching showed a trend of "first increase and then decrease", reaching the maximum in 2005, and then decreased due to stricter emission standard and enhanced environmental management. (2) according to spatial distribution, the emission of particulates from concrete batch mainly concentrated in the urban area with more human activities, and the area between the fifth ring and the sixth ring contributed the most. (3) through scenarios analysis, for further reducing the emission from concrete batching in 2020, more stricter standard for green production as well as powerful supervision is needed.

  6. 自密实混凝土在钢管混凝土结构中的应用%Application of Self-compacting concrete in the concrete filled steel tubular structure

    Institute of Scientific and Technical Information of China (English)

    张奋强

    2012-01-01

    本文结合工程实例,根据工程实际应用经验,提出对高抛自密实混凝土的工作机理、配合比设计、工作性评价方法、试验方法,介绍自密实混凝土在钢管混凝土结构中的应用。%Combined with the project examples,this article puts forward the working mechanism,mixture design,workability evaluation method and test methods of highly-casting self-compacting concrete according to actual engineering application experiences,then introduces the application of self-compacting concrete in steel-tube-concrete structure.

  7. Sulfate Attack on Concrete in an Inland Salt Lake Environment

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Several cracks were found on the surface of the concrete foundations that support the steel towers of the Luohe(漯河)-Huaiyang(淮阳) high-voltage electricity transmission line that is 20 years old and situated in an inland salt lake environment in North China.To analyze the deterioration mechanism that led to this condition, field investigations were carried out and several tests were conducted on the soil and the affected concrete, including XRD (X-ray diffraction), electric probe analysis, and chemical analysis.The results show that the concentration of sulfates is very high (0.39% wt.-0.67%wt.) in both the surrounding soil and the material around the coarse aggregates inside the concrete.Hence, sulfateattack could be one of the main causes of concrete deterioration.The percentage of sulfates in the surface layer of the concrete was higher than that in the inner layers of the concrete.The sulfates penetrate into the concrete and react with the hydrates of cement to form ettringite (AFt), which leads to increase in the volume and cracking of the concrete.

  8. Innovative reuse of concrete slurry waste from ready-mixed concrete plants in construction products.

    Science.gov (United States)

    Xuan, Dongxing; Zhan, Baojian; Poon, Chi Sun; Zheng, Wei

    2016-07-15

    Concrete slurry waste (CSW) is generated from ready-mixed concrete plants during concrete production and is classified as a corrosive hazardous material. If it is disposed of at landfills, it would cause detrimental effects for our surrounding environment and ecosystems due to its high pH value as well as heavy metal contamination and accumulation. A new method in this study has been introduced to effectively reuse CSW in new construction products. In this method, the calcium-silicate rich CSW in the fresh state was considered as a cementitious paste as well as a CO2 capture medium. The experimental results showed that the pH values of the collected CSWs stored for 28 days ranged from 12.5 to 13.0 and a drastic decrease of pH value was detected after accelerated mineral carbonation. The theoretically calculated CO2 sequestration extent of CSWs was from 27.05% to 31.23%. The practical water to solid ratio in the fresh CSW varied from 0.76 to 1.12, which had a significant impact on the compressive strength of the mixture with CSWs. After subjecting to accelerated mineral carbonation, rapid initial strength development and lower drying shrinkage for the prepared concrete mixture were achieved. PMID:27016667

  9. Innovative reuse of concrete slurry waste from ready-mixed concrete plants in construction products.

    Science.gov (United States)

    Xuan, Dongxing; Zhan, Baojian; Poon, Chi Sun; Zheng, Wei

    2016-07-15

    Concrete slurry waste (CSW) is generated from ready-mixed concrete plants during concrete production and is classified as a corrosive hazardous material. If it is disposed of at landfills, it would cause detrimental effects for our surrounding environment and ecosystems due to its high pH value as well as heavy metal contamination and accumulation. A new method in this study has been introduced to effectively reuse CSW in new construction products. In this method, the calcium-silicate rich CSW in the fresh state was considered as a cementitious paste as well as a CO2 capture medium. The experimental results showed that the pH values of the collected CSWs stored for 28 days ranged from 12.5 to 13.0 and a drastic decrease of pH value was detected after accelerated mineral carbonation. The theoretically calculated CO2 sequestration extent of CSWs was from 27.05% to 31.23%. The practical water to solid ratio in the fresh CSW varied from 0.76 to 1.12, which had a significant impact on the compressive strength of the mixture with CSWs. After subjecting to accelerated mineral carbonation, rapid initial strength development and lower drying shrinkage for the prepared concrete mixture were achieved.

  10. On the Degradation of Concrete in Marine Structures

    DEFF Research Database (Denmark)

    Burcharth, Hans F.; Hofman Frisch, P.; Freisleben, P.;

    1985-01-01

    practice and inherent problems are dealt with. Some recommendations on concrete specifications and production technique are also presented. The second part of the paper presents conventional concrete problems as observed in quaywall structures in harbour basins. On the background of the first two parts......Concrete is a cheap and extremely handy material and as such used extensively also in marine structures. Everybody dealing with this material knows examples of concrete apparently of almost infinite durability but also examples where serious degradation started shortly after completion...... of the structure. It is a fact that despite the tremendous amount of research and despite the material having been used for generations, the difference between success and failure is still small. The paper is in three parts. In the first part, which deals with concrete in breakwater structures, the conventional...

  11. Use of recycled fine aggregate in concretes with durable requirements.

    Science.gov (United States)

    Zega, Claudio Javier; Di Maio, Angel Antonio

    2011-11-01

    The use of construction waste materials as aggregates for concrete production is highly attractive compared to the use of non-renewable natural resources, promoting environmental protection and allowing the development of a new raw material. Several countries have recommendations for the use of recycled coarse aggregate in structural concrete, whereas the use of the fine fraction is limited because it may produce significant changes in some properties of concrete. However, during the last decade the use of recycled fine aggregates (RFA) has achieved a great international interest, mainly because of economic implications related to the shortage of natural sands suitable for the production of concrete, besides to allow an integral use of this type of waste. In this study, the durable behaviour of structural concretes made with different percentage of RFA (0%, 20%, and 30%) is evaluated. Different properties related to the durability of concretes such as absorption, sorptivity, water penetration under pressure, and carbonation are determined. In addition, the results of compressive strength, static modulus of elasticity and drying shrinkage are presented. The obtained results indicate that the recycled concretes have a suitable resistant and durable behaviour, according to the limits indicated by different international codes for structural concrete. PMID:21775123

  12. Incorporation of Mineral Admixtures in Sustainable High Performance Concrete

    Directory of Open Access Journals (Sweden)

    Nima Farzadnia

    2011-07-01

    Full Text Available Concrete is a widely used construction material around the world, and its properties have been undergoing changes through technological advancement. Numerous types of concrete have been developed to enhance the different properties of concrete. So far, this development can be divided into four stages. The earliest is the traditional normal strength concrete which is composed of only four constituent materials, which are cement, water, fine and coarse aggregates. With a fast population growth and a higher demand for housing and infrastructure, accompanied by recent developments in civil engineering, such as high-rise buildings and long-span bridges, higher compressive strength concrete was needed. At the beginning, reducing the water-cement ratio was the easiest way to achieve the high compressive strength. Thereafter, the fifth ingredient, a water reducing agent or super plasticizer, was indispensable. However, sometimes the compressive strength was not as important as some other properties, such as low permeability, durability and workability. Thus, high performance concrete was proposed and widely studied at the end of the last century. Currently, high-performance concrete is used in massive volumes due to its technical and economic advantages. Such materials are characterized by improved mechanical and durability properties resulting from the use of chemical and mineral admixtures as well as specialized production processes. This paper reviews the incorporation of mineral admixtures in binary, ternary and quaternary blended mortars in concrete.

  13. DOUBLE CURVED SURFACE (DCS) - Case study in reinforced concrete

    DEFF Research Database (Denmark)

    Esteves, Luis Pedro; Henriques, Goncalo

    2007-01-01

    This paper deals with digital integration between design and fabrication in order to construct a complex double-curved concrete surface. This research focused on practical application of CNC technology to polyurethane (EPS), as an alternative to concrete formwork. The influence of specific EPS pr...

  14. Concrete Hinges

    DEFF Research Database (Denmark)

    Halding, Philip Skov; Hertz, Kristian Dahl; Schmidt, Jacob Wittrup

    2014-01-01

    In the first part of the 20th century concrete hinges developed by Freyssinet and Mesnager were widely tested and implemented in concrete structures. The concrete hinges were used a great deal in closed-spandrel arch bridges. Since such a bridge type has not been competitive for the past 40 years......, the research in concrete hinges has not evolved significantly in that period. But introducing a new state-of-the-art concrete arch bridge solution (Pearl-Chain arches invented at the Technical University of Denmark) creates a necessity of a concrete hinge research based on modern standards. Back when research...... in concrete hinges was more common different designs were proposed for the geometry and reinforcement. Previous research focused on fatigue, multi-axial stresses around the hinge throat, and the relation between rotation- and moment. But many different test-setups were proposed by different researchers...

  15. Innovative Materials and Techniques in Concrete Construction : ACES Workshop

    CERN Document Server

    2012-01-01

    Recent years have seen enormous advances in the technology of concrete as a material, through which its strength, compactness and ductility can reach levels never dreamed of before. Thanks to these improved material properties, the strength and durability of concrete structures is greatly improved, their weight and dimensions reduced, the scope of concrete as a structural material is widened and – despite the higher material costs – overall economy is possible, with positive impacts on sustainability as well. Similar advances are underway in reinforcing materials, notably high strength steel and fibre-reinforced polymers, and in the way they are combined with concrete into high performance structures. Developments in materials and equipment, as well as new concepts, have lead to innovative construction techniques, reducing cost and construction time and making possible the application of concrete under extreme conditions of construction or environment. All these advances will be highlighted in the book by...

  16. Seismic Material Properties of Reinforced Concrete and Steel Casing Composite Concrete in Elevated Pile-Group Foundation

    OpenAIRE

    Zhou Mi; Yuan Wancheng; Zhang Yue

    2015-01-01

    The paper focuses on the material mechanics properties of reinforced concrete and steel casing composite concrete under pseudo-static loads and their application in structure. Although elevated pile-group foundation is widely used in bridge, port and ocean engineering, the seismic performance of this type of foundation still need further study. Four scale-specimens of the elevated pile-group foundation were manufactured by these two kinds of concrete and seismic performance characteristic of ...

  17. Electrical Resistance Tomography imaging of concrete

    KAUST Repository

    Karhunen, Kimmo

    2010-01-01

    We apply Electrical Resistance Tomography (ERT) for three dimensional imaging of concrete. In ERT, alternating currents are injected into the target using an array of electrodes attached to the target surface, and the resulting voltages are measured using the same electrodes. These boundary measurements are used for reconstructing the internal (3D) conductivity distribution of the target. In reinforced concrete, the metallic phases (reinforcing bars and fibers), cracks and air voids, moisture gradients, and the chloride distribution in the matrix carry contrast with respect to conductivity. While electrical measurements have been widely used to characterize the properties of concrete, only preliminary results of applying ERT to concrete imaging have been published so far. The aim of this paper is to carry out a feasibility evaluation with specifically cast samples. The results indicate that ERT may be a feasible modality for non-destructive evaluation of concrete. © 2009 Elsevier Ltd. All rights reserved.

  18. Damage Effects of Shelled Explosive Explosion in Concrete

    Directory of Open Access Journals (Sweden)

    Liu Yan

    2010-10-01

    Full Text Available The damage of concrete subjected to explosion loading is an important issue in defense engineering. The damage degree of concrete is related to many factors, such as the type of explosive charge, the depth of burial and the parameters of concrete. In this paper, three factors are considered for experiments of shelled explosives in concrete targets, which are the filling coefficient, length-to-diameter ratio and the depth of burial. The filling coefficient is from 0.1 to 1 by changing thickness of shell, and length-to-diameter ratio is from 2.5 to 10. The unconfined compressive strength of concrete target for test is 35MPa. The experimental results showed that the sizes of craters of concretes are varied as the filling coefficient, length-to-diameter ratio and the depth of burial. The optimal values of filling coefficient, length-to-diameter ratio and the depth of burial of shelled charges were obtained to get largest damage regions of concrete targets. This work provides a base for evaluating the damage of concrete and designing the penetrating warhead.Defence Science Journal, 2010, 60(6, pp.672-677, DOI:http://dx.doi.org/10.14429/dsj.60.434

  19. Performance of Recycled Asphalt Pavement as Coarse Aggregate in Concrete

    Directory of Open Access Journals (Sweden)

    Fidelis O. OKAFOR

    2010-12-01

    Full Text Available Recycled asphalt pavement (RAP is the reclaimed and reprocessed pavement material containing asphalt and aggregate. Most RAP is recycled back into pavements, and as a result there is a general lack of data pertaining to the mechanical properties for RAP in other possible applications such as Portland cement concrete. In the present study, some mechanical properties of Portland cement concrete containing RAP as coarse aggregate were investigated in the laboratory. Six concrete mixes of widely differing water/cement ratios and mix proportions were made using RAP as coarse aggregate. The properties tested include the physical properties of the RAP aggregate, the compressive and flexural strengths of the concrete. These properties were compared with those of similar concretes made with natural gravel aggregate. Results of the tests suggest that the strength of concrete made from RAP is dependent on the bond strength of the “asphalt-mortar” (asphalt binder-sand-filler matrix coatings on the aggregates and may not produce concrete with compressive strength above 25 MPa. However, for middle and low strength concrete, the material was found to compare favorably with natural gravel aggregate.

  20. Use of recycled plastics in concrete: A critical review.

    Science.gov (United States)

    Gu, Lei; Ozbakkaloglu, Togay

    2016-05-01

    Plastics have become an essential part of our modern lifestyle, and the global plastic production has increased immensely during the past 50years. This has contributed greatly to the production of plastic-related waste. Reuse of waste and recycled plastic materials in concrete mix as an environmental friendly construction material has drawn attention of researchers in recent times, and a large number of studies reporting the behavior of concrete containing waste and recycled plastic materials have been published. This paper summarizes the current published literature until 2015, discussing the material properties and recycling methods of plastic and the influence of plastic materials on the properties of concrete. To provide a comprehensive review, a total of 84 studies were considered, and they were classified into sub categories based on whether they dealt with concrete containing plastic aggregates or plastic fibers. Furthermore, the morphology of concrete containing plastic materials is described in this paper to explain the influence of plastic aggregates and plastic fibers on the properties of concrete. The properties of concretes containing virgin plastic materials were also reviewed to establish their similarities and differences with concrete containing recycled plastics. PMID:26970843

  1. Use of recycled plastics in concrete: A critical review.

    Science.gov (United States)

    Gu, Lei; Ozbakkaloglu, Togay

    2016-05-01

    Plastics have become an essential part of our modern lifestyle, and the global plastic production has increased immensely during the past 50years. This has contributed greatly to the production of plastic-related waste. Reuse of waste and recycled plastic materials in concrete mix as an environmental friendly construction material has drawn attention of researchers in recent times, and a large number of studies reporting the behavior of concrete containing waste and recycled plastic materials have been published. This paper summarizes the current published literature until 2015, discussing the material properties and recycling methods of plastic and the influence of plastic materials on the properties of concrete. To provide a comprehensive review, a total of 84 studies were considered, and they were classified into sub categories based on whether they dealt with concrete containing plastic aggregates or plastic fibers. Furthermore, the morphology of concrete containing plastic materials is described in this paper to explain the influence of plastic aggregates and plastic fibers on the properties of concrete. The properties of concretes containing virgin plastic materials were also reviewed to establish their similarities and differences with concrete containing recycled plastics.

  2. Safety Assessment in Installation of Precast Concrete

    Directory of Open Access Journals (Sweden)

    Yashrri S.N.

    2014-03-01

    Full Text Available This study was carried out to identify the safety aspects and the level of safety during the installation process in construction sites. A questionnaire survey and interviews were done to provide data on safety requirements in precast concrete construction. All of the interviews and the research questionnaire survey were conducted among contractors that are registered as class 1 to class 7 with the Construction Industry Development Board (CIDB and class A to class G with Pusat Khidmat Kontraktor (PKK in Penang. Returned questionnaires were analysed with the use of simple percentages and the Likert Scale analysis method to identify safety aspects of precast construction. The results indicate that the safety aspect implemented by companies involved in the precast construction process is at a good level in the safety aspect during bracing, propping, welding and grouting processes and at a very good level of safety in general aspects and safety aspects during lifting processes.

  3. Modelling of Filling, Microstructure Formation, Local Mechanical Properties and Stress – Strain Development in High-Pressure Die Cast Aluminium Castings

    DEFF Research Database (Denmark)

    Kotas, Petr; Hattel, Jesper Henri; Thorborg, Jesper;

    2009-01-01

    .e. whether the casting is based on cast iron- or aluminium-alloys. The distribution of local properties in a casting might vary substantially which makes it complex to optimize the casting with good accuracy. Often, mechanical simulations of the load situation are based on the assumption that the cast...... in an aluminium alloy is considered including simulation of the entire casting process with emphasis on microstructure formation related to mechanical properties such as elastic modulus, yield stress, ultimate strength and elongation as well as residual stresses. Subsequently, the casting is subjected to service...... inherently affects the component’s properties depending on design, metallurgy and casting technique. The wall thickness influences the coarseness of the microstructure and the material will have properties depending on the local metallurgical and thermal histories. This is independent on the material, i...

  4. Awareness programs and change in taste-based caste prejudice

    DEFF Research Database (Denmark)

    Banerjee, Ritwik; Datta Gupta, Nabanita

    Becker's theory of taste-based discrimination predicts that relative employment of the discriminated social group will improve if there is a decrease in the level of prejudice for the marginally discriminating employer. In this paper we experimentally test this prediction offered by Becker (1971......) in the context of caste in India, with management students (potential employers in the near future) as subjects. First, we measure caste prejudice and show that awareness through a TV social program reduces implicit prejudice against the lower caste and the reduction is sustained over time. Second, we find...... that the treatment reduces the prejudice levels of those in the left tail of the prejudice distribution - the group which can potentially affect real outcomes as predicted by the theory. And finally, a larger share of the treatment group subjects exhibit favorable opinoion about reservation in jobs for the lower...

  5. Awareness Programs and Change in Taste-based Caste Prejudice

    DEFF Research Database (Denmark)

    Banerjee, Ritwik; Gupta, Nabanita Datta

    2015-01-01

    Becker's theory of taste-based discrimination predicts that relative employment of the discriminated social group will improve if there is a decrease in the level of prejudice for the marginally discriminating employer. In this paper we experimentally test this prediction offered by Garry Becker...... in his seminal work on taste based discrimination, in the context of caste in India, with management students (potential employers in the near future) as subjects. First, we measure caste prejudice and show that awareness through a TV social program reduces implicit prejudice against the lower caste...... and the reduction is sustained over time. Second, we find that the treatment reduces the prejudice levels of those in the left tail of the prejudice distribution - the group which can potentially affect real outcomes as predicted by the theory. And finally, a larger share of the treatment group subjects exhibit...

  6. Aluminum-Based Cast In Situ Composites: A Review

    Science.gov (United States)

    Pramod, S. L.; Bakshi, Srinivasa R.; Murty, B. S.

    2015-06-01

    In situ composites are a class of composite materials in which the reinforcement is formed within the matrix by reaction during the processing. In situ method of composite synthesis has been widely followed by researchers because of several advantages over conventional stir casting such as fine particle size, clean interface, and good wettability of the reinforcement with the matrix and homogeneous distribution of the reinforcement compared to other processes. Besides this, in situ processing of composites by casting route is also economical and amenable for large scale production as compared to other methods such as powder metallurgy and spray forming. Commonly used reinforcements for Al and its alloys which can be produced in situ are Al2O3, AlN, TiB2, TiC, ZrB2, and Mg2Si. The aim of this paper is to review the current research and development in aluminum-based in situ composites by casting route.

  7. Mechanical properties of recycled PET fibers in concrete

    Directory of Open Access Journals (Sweden)

    Fernando Pelisser

    2012-08-01

    Full Text Available Fiber-reinforced concrete represents the current tendency to apply more efficient crack-resistant concrete. For instance, polyethylene terephthalate (PET is a polyester polymer obtained from recyclable bottles; it has been widely used to produce fibers to obtain cement-based products with improved properties. Therefore, this paper reports on an experimental study of recycled-bottle-PET fiber-reinforced concrete. Fibers with lengths of 10, 15 and 20 mm and volume fractions of 0.05, 0.18 and 0.30% related to the volume of the concrete were used. Physical and mechanical characterization of the concrete was performed, including the determination of compressive strength, flexural strength, Young's modulus and fracture toughness as well as analysis using mercury intrusion porosimetry (MIP and scanning electron microscopy (SEM. Flexure and impact tests were performed after 28 and 150 days. No significant effect of the fiber addition on the compressive strength and modulus of elasticity was observed. However, the Young's modulus was observed to decrease as the fiber volume increased. At 28 days, the concrete flexural toughness and impact resistance increased with the presence of PET fibers, except for the 0.05 vol.% sample. However, at 150 days, this improvement was no longer present due to recycled-bottle-PET fiber degradation in the alkaline concrete environment, as visualized by SEM observations. An increase in porosity also has occurred at 365 days for the fiber-reinforced concrete, as determined by MIP.

  8. Ductility of Reinforced Concrete Structures in Flexure

    DEFF Research Database (Denmark)

    Hestbech, Lars

    2013-01-01

    In this thesis, a rotational capacity model for flexural reinforced concrete elements is presented. The model is based on the general assumption, that any other failure mode than bending is prevented by proper design. This includes failure due to shear, anchorage, concentrated loads etc. Likewise......, beams governed by failure described by Kani’s Valley are not covered by the presented model. Hence, the model is delimited to shear reinforced elements failing in flexure. The rotational capacity model is divided into the following calculation procedures. 1. A cross sectional analysis of the critical...... section to obtain the maximum force in the tension reinforcement. 2. The variation of tensile forces in the reinforcement is determined from two contributions, moment and tension shift. 3. Correction of the tension force curve to tension stiffening effects. 4. Calculation of the rotational capacity...

  9. Sacred places in global big cities

    DEFF Research Database (Denmark)

    Greve, Anni

    The question of sacred places in modern societies involves an analytical perspective, which is not very prevalent in sociology, namely the anthropological or even better: the ethnological perspective. With this theme we have entered a veritable dispute, or controversy, in sociology about the rela......The question of sacred places in modern societies involves an analytical perspective, which is not very prevalent in sociology, namely the anthropological or even better: the ethnological perspective. With this theme we have entered a veritable dispute, or controversy, in sociology about...

  10. Review of Concrete Biodeterioration in Relation to Buried Nuclear Waste

    Energy Technology Data Exchange (ETDEWEB)

    Turick, C; Berry, C.

    2012-10-15

    Long-term storage of low level radioactive material in below ground concrete disposal units (DUs) (Saltstone Disposal Facility) is a means of depositing wastes generated from nuclear operations of the U.S. Department of Energy. Based on the currently modeled degradation mechanisms, possible microbial induced effects on the structural integrity of buried low level wastes must be addressed. Previous international efforts related to microbial impacts on concrete structures that house low level radioactive waste showed that microbial activity can play a significant role in the process of concrete degradation and ultimately structural deterioration. This literature review examines the recent research in this field and is focused on specific parameters that are applicable to modeling and prediction of the fate of concrete vaults housing stored wastes and the wastes themselves. Rates of concrete biodegradation vary with the environmental conditions, illustrating a need to understand the bioavailability of key compounds involved in microbial activity. Specific parameters require pH and osmotic pressure to be within a certain range to allow for microbial growth as well as the availability and abundance of energy sources like components involved in sulfur, iron and nitrogen oxidation. Carbon flow and availability are also factors to consider in predicting concrete biodegradation. The results of this review suggest that microbial activity in Saltstone, (grouted low level radioactive waste) is unlikely due to very high pH and osmotic pressure. Biodegradation of the concrete vaults housing the radioactive waste however, is a possibility. The rate and degree of concrete biodegradation is dependent on numerous physical, chemical and biological parameters. Results from this review point to parameters to focus on for modeling activities and also, possible options for mitigation that would minimize concrete biodegradation. In addition, key chemical components that drive microbial

  11. The formation of the structure of cast composites in different solidification conditions

    Directory of Open Access Journals (Sweden)

    A. Dolata-Grosz

    2008-05-01

    Full Text Available Purpose: In the research work the result of the reinforcement displacement and solidification analysis foraluminium cast composite with ceramic particles in different solidification conditions have been presented. Theresults of research on the solidification process for heterophase composite have been shown.Design/methodology/approach: : The solidification process of the AK12/ SiC+C composite suspension invarious heat abstraction conditions was recorded using the ThermaCAMTME25 photometer system for temperaturecontrol and measurement. The system, equipped with a thermovision camera, LCD display and a laser pointer, wasconnected to a SPIDER 8 recorder and used to monitor, record and, simultaneously, to visualize the temperaturechanges which take place during composites’ solidification. The structure analysis for composite casts wasperformed by means of optical microscopy.Findings: As the research has shown, moulds which abstract heat quickly, like a graphite or permanent mould,ensure obtaining a uniform distribution of ceramic particles in the matrix. A longer time of composite suspensionsolidification facilitates floatation and segregation of the reinforcing particles. Therefore, application of materialswhich prolong the solidification process, e.g. a sand mould, enables obtaining a gradient or laminar structure inheterophase composites.Practical implications: The mould’s material changes the nature of composite crystallization.Originality/value: It was found that the has a significant influence on the distribution of heterophasereinforcement in the matrix. By applying an appropriate mould material it is possible to shape the cast structureand the distribution of particles in the cast.

  12. The Tectonic Potentials of Concrete

    DEFF Research Database (Denmark)

    Egholm Pedersen, Ole

    2013-01-01

    with the industrial paradigm of standardization, have been put forward. This development is carried forward by computers and digital fabrication, but has yet to find its way into the production of building components. With regards to concrete casting, however, existing research do offer advancement towards...... construction is achievable though attention the properties of materials, structural logics and the craft of making. The thoughts of Marco Frascari which suggest a reading of details as a creator of meaning are introduced to be able to help establishing a progression in the case studies. Due to the narrow....... Addition is found to be the most widely used principle in contemporary practice, where the addition of Euclidian geometrical elements make up rectangular casting moulds which present a geometric restriction to the inherent isotropy of concrete. Subtraction, on the other hand, is found to be the most widely...

  13. Performance of Waterless Concrete

    Science.gov (United States)

    Toutanji, Houssam; Evans, Steve; Grugel, Richard N.

    2010-01-01

    The development of permanent lunar bases is constrained by performance of construction materials and availability of in-situ resources. Concrete seems a suitable construction material for the lunar environment, but water, one of its major components, is an extremely scarce resource on the Moon. This study explores an alternative to hydraulic concrete by replacing the binding mix of concrete (cement and water) with sulfur. Sulfur is a volatile element on the lunar surface that can be extracted from lunar soils by heating. Sulfur concrete mixes were prepared to investigate the effect of extreme environmental conditions on the properties of sulfur concrete. A hypervelocity impact test was conducted, having as its target a 5-cm cubic sample of sulfur concrete. This item consisted of JSC-1 lunar regolith simulant (65%) and sulfur (35%). The sample was placed in the MSFC Impact Test Facility s Micro Light Gas Gun target chamber, and was struck by a 1-mm diameter (1.4e-03 g) aluminum projectile at 5.85 km/s. In addition, HZTERN code, provided by NASA was used to study the effectiveness of sulfur concrete when subjected to space radiation.

  14. Cure-in-place process for seals

    Science.gov (United States)

    Hirasuna, Alan R.

    1981-01-01

    A cure-in-place process which allows a rubber seal element to be deformed to its service configuration before it is cross-linked and, hence, is a plastic and does not build up internal stress as a result of the deformation. This provides maximum residual strength to resist the differential pressure. Furthermore, the process allows use of high modulus formulations of the rubber seal element which would otherwise crack if cured and then deformed to its service configuration, resulting in a seal which has better gap bridging capability. Basically, the process involves positioning an uncured seal element in place, deforming it to its service configuration, heating the seal element, curing it in place, and then fully seating the seal.

  15. Experimental investigation of the relation between damage at the concrete-steel interface and initiation of reinforcement corrosion in plain and fibre reinforced concrete

    DEFF Research Database (Denmark)

    Michel, Alexander; Solgaard, Anders Ole Stubbe; Pease, Bradley Justin;

    2013-01-01

    Cracks in covering concrete are known to hasten initiation of steel corrosion in reinforced concrete structures. To minimise the impact of cracks on the deterioration of reinforced concrete structures, current approaches in (inter)national design codes often limit the concrete surface crack width...

  16. Numerical Analysis of Secondary Cooling in Continuous Slab Casting

    Institute of Scientific and Technical Information of China (English)

    Kee-Hyeon Cho; Byung-Moon Kim

    2008-01-01

    In the present study, a numerical optimization program has been developed for predicting the optimal secondary cooling patterns in a continuous slab caster. Optimization strategy using Broydon-Fletcher-Goldfarb-Shanno (BFGS) method is carried out by determining the constant heat transfer coefficients in each spray zone, which could satisfy the casting conditions and metallurgical criteria specified by the engineer. From the present results, it is found that even a slight variation in the pouring temperature, allowable surface temperature, and casting speed could give rise to the changes in the cooling pattern throughout the spray zones.

  17. Modelling the Loss of Steel-Concrete Bonds in Corroded Reinforced Concrete Beams

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    2007-01-01

    The existing stochastic models for deterioration of reinforced concrete structures is extended by adding modelling of "loss of bond" due to corrosion between the reinforcement bars and the surrounding concrete.......The existing stochastic models for deterioration of reinforced concrete structures is extended by adding modelling of "loss of bond" due to corrosion between the reinforcement bars and the surrounding concrete....

  18. Jamestown and Disneyland: Two Places in Time.

    Science.gov (United States)

    Scrofani, E. Robert; Tideman, Robert

    This unit for high school students uses two dissimilar places in time; (2) Jamestown, Virginia, founded in 1607, one of the earliest settlements in the United States and (2) Disneyland, California, built in 1956, an institution of contemporary culture. The lessons address two fundamental questions in geography: (1) where? and (2) why here rather…

  19. Preferred orientation of ettringite in concrete fractures

    Energy Technology Data Exchange (ETDEWEB)

    Wenk, Hans-Rudolf; Monteiro, Paulo J.M.; Kunz, Martin; Chen, Kai; Tamura, Nobumichi; Lutterotti, Luca; Delacroz, John

    2009-01-31

    Sulfate attack and the accompanying crystallization of fibrous ettringite [Ca{sub 6}Al{sub 2}(OH){sub 12}(SO{sub 4}){sub 3} {center_dot} 26H{sub 2}O] cause cracking and loss of strength in concrete structures. Hard synchrotron X-ray microdiffraction is used to quantify the orientation distribution of ettringite crystals. Diffraction images are analyzed using the Rietveld method to obtain information on textures. The analysis reveals that the c axes of the trigonal crystallites are preferentially oriented perpendicular to the fracture surfaces. By averaging single-crystal elastic properties over the orientation distribution, it is possible to estimate the elastic anisotropy of ettringite aggregates.

  20. A Novel Process in Semi-Solid Metal Casting

    Institute of Scientific and Technical Information of China (English)

    Bijan Abbasi-Khazaei; Saeid Ghaderi

    2012-01-01

    In this research a new process for semi-solid casting of ductile iron based on the high nucleation rate combined with locally mechanical stirring is presented. In this process at first fully liquid ductile iron was poured on the peripheral surface of a wheel rotating against pouring direction. At this stage, the solid crystals nucleated at the chilling surface were pushed to the melt by a heat resistance steel cutter and finally the semi-solid slurry was generated. Reheating treatment was done on the samples to achieve more efficiency of semi-solid casting process. The effects of the travelling distance of solid particles during casting, the reheating time and temperature were examined. The results showed that the process effectively changes the dendrite structure to globular one.

  1. EFFECT OF WASTE MINERAL ADDITIVES ON FLOW STABILITY OVER TIME IN SELF-COMPACTING CONCRETE MIXES WITH LOW CLINKER CONTENT

    Directory of Open Access Journals (Sweden)

    Anna M. Grabiec

    2015-09-01

    Full Text Available Contemporary solutions in concrete technology are varied, and consist in e.g. the use of new generation concretes, including the most spectacular achievement of the 1990s – self-compacting concrete (SCC being the subject of continuous research, as well as protection of the environment against excessive anthropogenic pressures, such as carbon dioxide which is a major emission substance from the cement industry. The studies analysed the possibilities for replacing part of the clinker binder (cement CEM I 42.5 R in self-compacting concrete with three types of waste mineral additives: fly ash, limestone powder, and granite powder. Focus was placed on key technological characteristics of concrete mixes: air content and rheological properties, maximal diameter of slump-flow and changes thereof over time, as well as the mix’s flow time into the 500 mm diameter, determining the flow dynamics. 28-day compressive strength of the concrete was recognised as a secondary property which in self-compacting concretes results from achieving the right range of the mix’s rheological properties. Concretes were produced using gravel-sand aggregate in 3-fraction composition and a high-efficiency superplasticiser. The studies were conducted as a planned experiment in the 3-ingredient mixes plan.

  2. Improvement of die life in high speed injection die casting

    Institute of Scientific and Technical Information of China (English)

    Yasuhiro Arisuda; Akihito Hasuno; Junji Yoshida; Kazunari Tanii

    2008-01-01

    High-speed injection die casting is an efficient manufacturing technology for upgrading aluminum die-cast products. However, deficiencies (such as die damage in eady period) due to larger load on the molding die compared with conventional technology have brought new challenges. In this study, the cause of damage generated in super high-speed injection was investigated by the combination of experimental observation of the dies and CAE simulation (e.g. die temperature analysis, flow analysis and thermal stress analysis). The potential countermeasures to solve the above problems were also proposed.

  3. [Which place for physicians in blood supply?].

    Science.gov (United States)

    Danic, B; Pelletier, B

    2013-05-01

    Historically, blood transfusion has been divised, enhanced and organized by physicians. The special status of blood led to ensure that collection of blood and its components were placed under the supervision of a physician. Throughout its history, blood transfusion organization in France has established an exclusive exercise of the collection of blood and its components entrusted to doctors, thus creating the concept of "medicine of donation". This view is changing, and programmed exercise of this activity by nurses led to question about this profession perimeter, its necessary evolution, and finally about the place of physicians in blood supply. PMID:23537956

  4. 谈自密实混凝土施工技术%Discussion on the self-compacting concrete construction technique

    Institute of Scientific and Technical Information of China (English)

    黄巍

    2012-01-01

    以北京市南水北调工程水工隧洞现浇自密实混凝土工程为例,对自密实混凝土配合比设计、原材料选择和工程应用施工操作要点等加以说明和介绍,以期促进自密实混凝土施工技术的推广应用。%Taking the cast-in-place self-compacting concrete project in South-North Water transfer project in Beijing as the background,the paper indicates and introduces the proportional ratio,the selection of raw materials,and the operation points for the engineering application for the self-compacting concrete,so as to enhance the extensive application for the self-compacting concrete construction.

  5. Reuse of Lathe Waste Steel Scrap in Concrete Pavements

    Directory of Open Access Journals (Sweden)

    Pooja Shrivastavaa

    2014-12-01

    Full Text Available These project works assess on the study of the workability and mechanical strength properties of the concrete reinforced with industrialized waste fibers or the recycled fibers. In each lathe industries wastes are available in form of steel scraps are yield by the lathe machines in process of finishing of different machines parts and dumping of these wastes in the barren soil contaminating the soil and ground water that builds an unhealthy environment. Now a day’s these steel scraps as a waste products used by innovative construction industry and also in transportation and highway industry. In addition to get sustainable progress and environmental remuneration, lathe scrap as worn-recycle fibers with concrete are likely to be used. When the steel scrap reinforced in concrete it acquire a term; fiber reinforced concrete and steel fibers in concrete defined as steel fiber reinforced concrete (SFRC.Different experimental studies are done to identify about fresh and hardened concrete properties of steel scrap fiber reinforced concrete (SSFRC and their mechanical properties are found to be increase due to the addition of steel scrap in concrete i.e. compressive strength, flexural strength, impact strength, fatigue strength and split tensile strength were increased but up to 0.5-2% scrap content . When compared with usual concrete to SSFRC, flexural strength increases by 40% and considerable increases in tensile and compressive strength. These steel scrap also aid to improve the shrinkage reduction, cracking resistance i.e. preventing crack propagation and modulus of elasticity. The workability of fresh SSFRC are carried out by using slump test but it restricted to less scrap contents. This work focuses on the enhancement of structural strength and improvement in fatigue life of concrete pavements by reuse of scrap steel in concrete. These concrete roads with SSFRC promises an appreciably eminent design life, offer superior serviceability and

  6. Combination Of The Non-Destructive Methods For Evaluating The Quality Of Concrete Used In Structures In Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Mr. R. OBAD

    2014-12-01

    Full Text Available The study is aboutthe use and comparison of three non-destructive methods (dynamic auscultation, sclerometric auscultation and auscultation by RADAR (Radio Detecting and Ranging to monitor and assess the quality of concrete. Samples of reinforced concrete panels, dimensions 200x100x30 cm of concrete dosed at 350 kg/m3 with diverse E/C ratio were achieved, conserved in the laboratory and subjected to various non-destructive test. The synthesis of the results obtained by auscultation RADAR shows a decrease in the propagation speed of the electromagnetic wave with an increase of the E/C ratio and a decrease in resistance of concrete values measured and confirmed by other non-destructive techniques (sclerometric and dynamic auscultations. This shows that more the dielectric constant is high, morethe concrete resistance is reduced, and conversely the opposite.

  7. The metaphor in the Changing Place

    Institute of Scientific and Technical Information of China (English)

    李晨

    2013-01-01

    This paper attempts to use some basic principles in the modern metaphor theory in the cognitive theory to analyze the Changing Place, which is one of the representatives of David Lodge’s academic fictions, so that it can help to have a better understanding of the metaphor used in this fiction.

  8. Market Design in Chinese Market Places

    NARCIS (Netherlands)

    B. Krug (Barbara); H. Hendrischke (Hans)

    2012-01-01

    textabstractThe Market Design (MD) approach to institutional analysis provides the analytical tools to evaluate endogenous institution building in local market places irrespective of the institutional setting of the national economy. Implicit in this analysis of endogenous institution building at th

  9. Market design in Chinese market places

    NARCIS (Netherlands)

    B. Krug (Barbara); H. Hendrischke (Hans)

    2012-01-01

    textabstractThe market design (MD) approach to institutional analysis provides the analytical tools to evaluate endogenous institution building in local market places irrespective of the institutional setting of the national economy. Implicit in this analysis of endogenous institution building at th

  10. CASTING DEFECT MODELING IN AN INTEGRATED COMPUTATIONAL MATERIALS ENGINEERING APPROACH

    Energy Technology Data Exchange (ETDEWEB)

    Sabau, Adrian S [ORNL

    2015-01-01

    To accelerate the introduction of new cast alloys, the simultaneous modeling and simulation of multiphysical phenomena needs to be considered in the design and optimization of mechanical properties of cast components. The required models related to casting defects, such as microporosity and hot tears, are reviewed. Three aluminum alloys are considered A356, 356 and 319. The data on calculated solidification shrinkage is presented and its effects on microporosity levels discussed. Examples are given for predicting microporosity defects and microstructure distribution for a plate casting. Models to predict fatigue life and yield stress are briefly highlighted here for the sake of completion and to illustrate how the length scales of the microstructure features as well as porosity defects are taken into account for modeling the mechanical properties. Thus, the data on casting defects, including microstructure features, is crucial for evaluating the final performance-related properties of the component. ACKNOWLEDGEMENTS This work was performed under a Cooperative Research and Development Agreement (CRADA) with the Nemak Inc., and Chrysler Co. for the project "High Performance Cast Aluminum Alloys for Next Generation Passenger Vehicle Engines. The author would also like to thank Amit Shyam for reviewing the paper and Andres Rodriguez of Nemak Inc. Research sponsored by the U. S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office, as part of the Propulsion Materials Program under contract DE-AC05-00OR22725 with UT-Battelle, LLC. Part of this research was conducted through the Oak Ridge National Laboratory's High Temperature Materials Laboratory User Program, which is sponsored by the U. S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Program.

  11. Convective heat transfer correlations for molten core debris pools growing in concrete

    International Nuclear Information System (INIS)

    The heat and mass transfer processes taking place in volumetrically-heated pools are of interest because of their relevance in post accident heat removal analyses for fast reactors. Earlier studies on volumetrically-heated pools have focused on natural convection phenomena. These, however, do not apply for molten core debris pools growing in concrete since large amounts of gas will be released by the concrete. These gases will vigorously mix the pool. Knowledge of the heat transfer rates at the pool boundaries is necessary in order to assess the passive core retention capability of the concrete support structure below the reactor vessel. Hence, the main objectives of this investigation have been to experimentally simulate the gas evolution process at the pool boundaries and determine the effect of gas release on the heat transfer rates along the boundaries. Nusselt-type correlations have been obtained for the downward, sideward, and upward heat transfer rates

  12. Behavior’s Evolution of Micro-Concretes in Combined Sulphate and Magnesium Aggressive Environments, at Three -Years Old

    Directory of Open Access Journals (Sweden)

    Mircea Rujanu

    2010-03-01

    Full Text Available In the present paper is analysed concrete behavior from strength structure elements, subjected to combined sulphatic and magnesian aggressive actions. In order to clearly relieve cement influence regarding corrosion behavior and to be as close as possible of concrete structural characteristics, tests are realized on standard mortars, which from compositional point of view are mocro-concretes. These were used different W/C ratios in order to obtain different structural characteristics, knowing that in the first period after casting, when concrete porosity is sensibly higher, corrosion process is more emphatic, with subsequent negative effects. It was taken into account the fact that sulphatic corrosion effect appears after a long duration of aggressive agent action, in the present paper proposing a three year duration for aggressive attack. In the same time it was considered the fact that usual cement for structural elements is composite cement type CEM II/A-S 32,5, studying combined sulphatic and magnesian corrosion evolution on a large type of micro-concrete compositions with different compactness and aggressive agent concentrations.

  13. Modelling of the fracture toughness anisotropy in fiber reinforced concrete

    Directory of Open Access Journals (Sweden)

    S. Tarasovs

    2016-01-01

    Full Text Available Steel fiber reinforced concrete is potentially very promising material with unique properties, which currently is widely used in some applications, such as floors and concrete pavements. However, lack of robust and reliable models of fiber reinforced concrete fracture limits its application as structural material. In this work a numerical model is proposed for predicting the crack growth in fiber reinforced concrete. The mixing of the steel fibers with the concrete usually creates nonuniform fibers distribution with more fibers oriented in horizontal direction, than in vertical. Simple numerical models of fiber reinforced concrete require a priori knowledge of the crack growth direction in order to take into account bridging action of the fibers, which depends on the fibers orientation. In proposed model user defined elements are used to calculate the bridging force during the course of the analysis when the crack starts to grow. Cohesive elements were used to model the crack propagation in the concrete matrix. In cohesive zone model the cohesive elements are embedded between all solid elements to simulate the arbitrary crack path. The bridging effect of the fibers are modeled as nonlinear springs, where the stiffness of the springs is defined from experimentally measured pull-out force and the angle between the fiber and crack opening direction.

  14. A study of the coupling relationship between concrete surface temperature and concrete surface emissivity in natural conditions.

    Science.gov (United States)

    Tang, Lin-Ling; Chen, Xiao-Ling; Wang, Jia-Ning; Zhao, Hong-Mei; Huang, Qi-Ting

    2014-07-01

    Land surface emissivity (LSE) has already been recognized as a crucial parameter for the determination of land surface temperature (LST). There is an ill-posed problem for the retrieval of LST and LSE. And laboratory-based emissivity is measured in natural constant conditions, which is limited in the application in thermal remote sensing. To solve the above problems, the coupling of LST and LSE is explored to eliminate temperature effects and improve the accuracy of LES. And then, the estimation accuracy of LST from passive remote sensing images will be improved. For different land surface materials, the coupling of land surface emissivity and land surface temperature is various. This paper focuses on studying concrete surface that is one of the typical man-made materials in urban. First the experiments of measuring concrete surface emissivity and concrete surface temperature in natural conditions are arranged reasonably and the suitable data are selected under ideal atmosphere conductions. Then to improve the determination accuracy of concrete surface emissivity, the algorithm worked on the computer of Fourier Transform Infrared Spectroradiometer (FTIR) has been improved by the most adapted temperature and emissivity separation algorithm. Finally the coupling of concrete surface temperature and concrete surface emissivity is analyzed and the coupling model of concrete surface temperature and concrete surface emissivity is established. The results show that there is a highest correlation coefficient between the second derivative of emissivity spectra and concrete surface temperature, and the correlation coefficient is -0.925 1. The best coupling model is the stepwise regression model, whose determination coefficient (R2) is 0.886. The determination coefficient (R2) is 0.905 and the root mean squares error (RMSE) is 0.292 1 in the validation of the model. The coupling model of concrete surface temperature and concrete surface emissivity under natural conditions

  15. A study of the coupling relationship between concrete surface temperature and concrete surface emissivity in natural conditions.

    Science.gov (United States)

    Tang, Lin-Ling; Chen, Xiao-Ling; Wang, Jia-Ning; Zhao, Hong-Mei; Huang, Qi-Ting

    2014-07-01

    Land surface emissivity (LSE) has already been recognized as a crucial parameter for the determination of land surface temperature (LST). There is an ill-posed problem for the retrieval of LST and LSE. And laboratory-based emissivity is measured in natural constant conditions, which is limited in the application in thermal remote sensing. To solve the above problems, the coupling of LST and LSE is explored to eliminate temperature effects and improve the accuracy of LES. And then, the estimation accuracy of LST from passive remote sensing images will be improved. For different land surface materials, the coupling of land surface emissivity and land surface temperature is various. This paper focuses on studying concrete surface that is one of the typical man-made materials in urban. First the experiments of measuring concrete surface emissivity and concrete surface temperature in natural conditions are arranged reasonably and the suitable data are selected under ideal atmosphere conductions. Then to improve the determination accuracy of concrete surface emissivity, the algorithm worked on the computer of Fourier Transform Infrared Spectroradiometer (FTIR) has been improved by the most adapted temperature and emissivity separation algorithm. Finally the coupling of concrete surface temperature and concrete surface emissivity is analyzed and the coupling model of concrete surface temperature and concrete surface emissivity is established. The results show that there is a highest correlation coefficient between the second derivative of emissivity spectra and concrete surface temperature, and the correlation coefficient is -0.925 1. The best coupling model is the stepwise regression model, whose determination coefficient (R2) is 0.886. The determination coefficient (R2) is 0.905 and the root mean squares error (RMSE) is 0.292 1 in the validation of the model. The coupling model of concrete surface temperature and concrete surface emissivity under natural conditions

  16. Promoting the use of crumb rubber concrete in developing countries.

    Science.gov (United States)

    Batayneh, Malek K; Marie, Iqbal; Asi, Ibrahim

    2008-11-01

    The use of accumulated waste materials in third world countries is still in its early phases. It will take courage for contractors and others in the construction industry to recycle selected types of waste materials in the concrete mixes. This paper addresses the recycling of rubber tires accumulated every year in Jordan to be used in concrete mixes. The main objectives of this research were to provide more scientific evidence to support the use of legislation or incentive-based schemes to promote the reuse of accumulated waste tires. This research focused on using crumb tires as a replacement for a percentage of the local fine aggregates used in the concrete mixes in Jordan. Different concrete specimens were prepared and tested in terms of uniaxial compression and splitting tension. The main variable in the mixture was the volumetric percentage of crumb tires used in the mix. The test results showed that even though the compressive strength is reduced when using the crumb tires, it can meet the strength requirements of light weight concrete. In addition, test results and observations indicated that the addition of crumb rubber to the mix has a limited effect toward reducing the workability of the mixtures. The mechanical test results demonstrated that the tested specimens of the crumb rubber concrete remained relatively intact after failure compared to the conventional concrete specimens. It is also concluded that modified concrete would contribute to the disposal of the non-decaying scrap tires, since the amount being accumulated in third world countries is creating a challenge for proper disposal. Thus, obliging authorities to invest in facilitating the use of waste tires in concrete, a fundamental material to the booming construction industry in theses countries, serves two purposes. PMID:18956487

  17. Indian Place Names in South Dakota.

    Science.gov (United States)

    Gasque, Thomas J.

    A cursory examination of place names on a map of South Dakota does not reflect the important role that Indians have played in the state and their relation to the land framed by its borders. Only three towns with populations over 1,000 bear names that clearly come from Indian languages: Sioux Falls, Sisseton, and Yankton. The hostile relationship…

  18. Exploratory Study of Palm Oil Fuel Ash as Partial Cement Replacement in Oil Palm Shell Lightweight Aggregate Concrete

    Directory of Open Access Journals (Sweden)

    K. Muthusamy

    2014-07-01

    Full Text Available In Malaysia, issue of environmental pollution resulting from disposal of Palm Oil Fuel Ash (POFA which is a by-product from palm oil mill has initiated research to incorporate this waste in Oil Palm Shell (OPS lightweight aggregate concrete production. The current study investigates the effect of palm oil fuel ash content as partial cement replacement towards compressive strength OPS lightweight aggregate concrete. Several OPS lightweight aggregate concrete mixes were produced by replacing various percentage of POFA ranging from 10, 20, 30, 40 and 50%, respectively by weight of cement. All the mixes were cast in form of cubes and then subjected to water curing until the testing date. The compressive strength test is conducted in accordance to BSEN 12390 (2009 at 7 and 28 days. From the results, it was observed that the combination of appropriate POFA content would enhance the compressive strength of OPS lightweight aggregate concrete. Specimen produced using 20% POFA as partial cement replacement exhibit higher value of compressive strength than that of control OPS lightweight aggregate concrete. However, mixes consisting POFA up to 50% is also suitable for structural application.

  19. Size Effects on the Bending Behaviour of Reinforced Concrete Beams

    DEFF Research Database (Denmark)

    Brincker, Rune; Henriksen, M. S.; Christensen, F. A.;

    1999-01-01

    Load-deformation curves for reinforced concrete beams subjected to bending show size effects due to tensile failure of the concrete at early stages in the failure process and due to compression failure of the concrete when the final failure takes place. In this paper these effects are modelled...

  20. Stabilization of electric-arc furnace dust in concrete

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Caldas de Souza

    2010-12-01

    Full Text Available Electric-arc furnace dust (EAFD is a by-product of steel production and recycling. This fine-grained material contains high amounts of zinc and iron as well as significant amounts of potentially toxic elements such as lead, cadmium and chromium. Therefore, the treatment and stabilization of this industrial residue is necessary. Concrete is a well-known suitable environment for stabilization/solidification of materials which have leachable elements in need of fixation. The effect of the EAFD content on the mechanical and chemical performance of Portland cement concrete is investigated in this paper. The effect of the EAFD content on the setting time of cement slurry was also analyzed. The axial compressive strength of the concrete samples increases with the EAFD addition in the range of 10 to 20 wt. (% EAFD; also the tensile strength increases with the EAFD addition. An increase in EAFD content significantly increases the setting time of the concrete. The acetic acid leaching and water solubilization tests indicate low mobility of the potentially toxic elements from the EAFD concrete composite. The results of the immersion tests show that the addition of EAFD to the concrete seems to reduce chloride penetration, which may help prevent pitting corrosion in reinforced concrete.