WorldWideScience

Sample records for cast in place concrete

  1. 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 ...

  2. 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.

  3. Fundamental study on pull-out strength of cast-in-place anchor bolt in concrete subjected to high temperature

    International Nuclear Information System (INIS)

    Some recent research on high temperature behavior of concrete shows that its strength will decrease with further increase of temperature, and other mechanical properties also get worse, due to drying shrinkage, thermal stress and so on. Cast-in place anchor bolts are used in many structural applications. There is possibility that these anchor bolts will be exposed to high temperature in a short time by some accident, and that the pull-out strength will decrease. This paper describes a study on the pull-out strength of a cast-in-place anchor bolt installed in concrete which is subjected to high temperatures up to 500degC to obtain basic experimental data and to examine the response of cast-in-place anchor bolts to high temperature exposure. Tests results show that the pull-out strength under high temperature decreases significantly. The pull-out strength during heating and after heating up to 500degC was 20% and 50% of it in normal temperature, respectively. (author)

  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. 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

  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. 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.

  8. Self-Placing Concrete

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Certain concrete pours have areas where the congestion of reinforcing bars make placement of concrete almost impossible. Using conventional placing and vibration techniques, the resulting concrete can have considerable honeycombing due to the development of voids. Self-placing concrete is a possible solution to the problem. Also known as self-compactable concrete, self-consolidating concrete, flowable concrete, and non-vibration concrete. These concretes eliminate the need for vibration in a ...

  9. 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...

  10. 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.

  11. A development of numerical analysis model for tensile capacity evaluation of cast-in-place anchor

    International Nuclear Information System (INIS)

    Numerical analysis is carried out to identify the appropriateness of the design codes that is available for the tensile design of fastening system at Nuclear Power Plant (NPP) in this study. This study is intended for the cast-in-place anchor that is widely used for the fastening of equipment in Korean NPPs. The microplane model and the elastic-perfectly plastic model are employed for the quasi-brittle material like concrete and for the ductile material like anchor bolt as constitutive model for numerical analysis and smeared crack model is employed for the crack and damage phenomena. The developed numerical model is verified on a basis of the various test data of cast-in-place anchor. The appropriateness of both ACI 349 Code and CCD approach of CEB-FIP Code is evaluated for the tensile design of cast-in-place anchor and it is proved that both design codes give a conservative results compared with real tensile capacity of cast-in-place anchor

  12. Analytical Evaluation of Reinforced Concrete Pier and Cast-in-Steel-Shell Pile Connection Behavior considering Steel-Concrete Interface

    OpenAIRE

    Jiho Moon; Dawn E. Lehman; Charles W. Roeder; Hak-Eun Lee; Tae-Hyung Lee

    2016-01-01

    The seismic design of bridges may require a large-diameter deep pile foundation such as a cast-in-steel-shell (CISS) pile where a reinforced concrete (RC) member is cast in a steel casing. In practice, the steel casing is not considered in the structural design and the pile is assumed to be an RC member. It is partially attributed to the difficulties in evaluation of composite action of a CISS pile. However, by considering benefits provided by composite action of the infilled concrete and the...

  13. Analytical Evaluation of Reinforced Concrete Pier and Cast-in-Steel-Shell Pile Connection Behavior considering Steel-Concrete Interface

    Directory of Open Access Journals (Sweden)

    Jiho Moon

    2016-01-01

    Full Text Available The seismic design of bridges may require a large-diameter deep pile foundation such as a cast-in-steel-shell (CISS pile where a reinforced concrete (RC member is cast in a steel casing. In practice, the steel casing is not considered in the structural design and the pile is assumed to be an RC member. It is partially attributed to the difficulties in evaluation of composite action of a CISS pile. However, by considering benefits provided by composite action of the infilled concrete and the steel casing, both the cost and size of CISS pile can be reduced. In this study, the structural behavior of the RC pier and the CISS pile connection is simulated by using an advanced 3D finite element (FE method, where the interface between the steel and concrete is also modeled. Firstly, the FE model is verified. Then, the parametric study is conducted. The analysis results suggest that the embedment length and the friction coefficient between the steel casing and the infilled concrete affect the structural behavior of the RC pier. Finally, the minimum embedment length with reference to the AASHTO design guideline is suggested considering the composite action of the CISS pile.

  14. 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

  15. An evaluation of tensile capacity of cast-in-place anchor with crack

    International Nuclear Information System (INIS)

    Actual model tests are carried out to develop the model that can accurately incorporate the effect of the various types of cracks 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. 115 test specimens with single anchor are constructed on a basis of ASTM E488 under 23 cracked conditions and plain concrete for these actual model tests. As principal test variables related to crack, the crack width, the crack depth, and the distance between crack and anchor etc. are chosen. In order to apply the tensile force, 100 tonf-capacity actuator is used with displacement control of 0.5 mm/min. Through these test results, the model incorporating the effect of various types of cracks accurately, is developed and will be available for the an chorage capacity evaluation for seismic qualification of equipment in USI A -46 NPPs and anchorage design of new NPPs

  16. Early-age durability assessment of cast-in-place RC bridge deck

    Science.gov (United States)

    Aktan, Haluk M.; Yaman, Ismail O.; Udegbunam, Oge; Hearn, Nataliya

    2000-06-01

    A novel method for evaluating concrete permeability at an early age is being developed for use in performance-related specifications where the material durability is specified as a performance parameter. In developing the method, the fundamental relationship between ultrasonic pulse velocity (UPV) and permeability of a porous medium is derived. An experimental relationship between UPV and concrete permeability is also established which strongly correlates with its theoretical counterpart. This experimental relationship is developed from UPV and permeability tests conducted on specimens made from a series of concrete grades. The experimental relation utilized the data collected from specimens made from a total of 20 bridge deck normal concrete mixes corresponding to five w/c (water-cement ratio) groups of 0.35, 0.40, 0.45, 0.50 and 0.55. The implementation procedure developed is the application of the 'paste efficiency' principle. In implementing 'paste efficiency' principle during the casting of a bridge deck, standard specimens are prepared in the field and cured in the laboratory. UPV measurements are obtained at an early age both from the deck and the standard specimens. The decrease in UPV from standard specimens indicates paste quality loss (PQL) and is proportional to the increase in permeability of deck concrete.

  17. ESTIMATION OF IN-PLACE STRENGTH OF CONCRETE WITH COMBINED NONDESTRUCTIVE METHOD

    Directory of Open Access Journals (Sweden)

    İsa YÜKSEL

    2003-02-01

    Full Text Available This paper presents estimation of concrete strength by the SONREB method that is a combined non-destructive testing method and application of the method on a reinforced concrete building structure. Comparison of results of both destructive and non-destructive test results is introduced also. The SONREB method is based on evaluation of the combination of Schmidt hammer readings and ultrasonic pulse velocity measurements. The measured material properties are correlated with compressive strength of concrete by using special iso-strength curves established in the laboratory. The strength is also checked with strength of cores drilled from suitable positions on the building. In-place strength of concrete giving without any structural damage to the structure could be estimated rapidly and approximately with the SONREB method. It was concluded that the special isostrength curves increase sensitivity of in-place compressive strength estimation of concrete.

  18. 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.

  19. 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.

  20. Measurement of concrete E-modulus evolution since casting: A novel method based on ambient vibration

    International Nuclear Information System (INIS)

    The use of ambient vibration tests to characterize the evolution of E-modulus of concrete right after casting is investigated in this paper. A new methodology is proposed, which starts by casting a concrete cylindrical beam inside a hollow acrylic formwork. This beam is then placed horizontally, simply supported at both extremities, and vertical accelerations resulting from ambient vibration are measured at mid-span. Processing these mid-span acceleration time series using power spectral density functions allows a continuous identification of the first flexural frequency of vibration of the composite beam, which in turn is correlated with the evolutive E-modulus of concrete since casting. Together with experiments conducted with the proposed methodology, a complementary validation campaign for concrete E-modulus determination was undertaken by static loading tests performed on the composite beam, as well as by standard compressive tests of concrete cylinders of the same batch loaded at different ages.

  1. Partially rib precast and cast-in-situ floors with cellular-concrete blocks (rus

    Directory of Open Access Journals (Sweden)

    Gorshkov A.S.

    2011-10-01

    Full Text Available The object of research is precast and cast-in-situ inserted floor with cellular-concrete items used for reduction of structure weight. The used materials and installation technologies are considered.The aim of this work is analysis of strength and deformability of floor by two different methods: analytical calculation and calculation by finite element method using SCAD. It was shown that the finite element calculation is more precise and also it allows to use armature of lesser diameter that decreases the cost of the floor.For adjustment of given model and life duration of the structure the full-scale tests are necessary.

  2. 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...

  3. 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.

  4. 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...

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. Stiffness of reinforced concrete walls resisting in-place shear -- Tier 2: Aging and durability of concrete used in nuclear power plants. Final report

    International Nuclear Information System (INIS)

    Reinforced concrete walls are commonly used in power-plant construction to resist earthquake effects. Determination of wall stiffness is of particular importance for establishing design forces on attached equipment. Available experimental data indicate differences between the measured and calculated stiffness of walls in cases where concrete mechanical properties are well defined. Additional data indicate that in-situ concrete mechanical properties may differ significantly from those specified in design. The work summarized in this report was undertaken to investigate the mechanical properties of concrete considering aging and deterioration. Existing data on mechanical properties of concrete are evaluated, and new tests are carried out on concrete cylinders batched for nuclear power plants and stored under controlled conditions for up to twenty years. It is concluded that concretes batched for nuclear power plants commonly have 28-day strength that exceeds the design value by at least 1000 psi. Under curing conditions representative of those in the interior of thick concrete elements, strength gain with time can be estimated conservatively using the expression proposed by ACI Committee 209, with strengths at 25 years being approximately 1.3 times the 28-day strength. Young's modulus can be estimated using the expression given by ACI Committee 318. Variabilities in mechanical properties are identified. A review of concrete durability identified the main causes and results of concrete deterioration that are relevant for the class of concretes and structures commonly used in nuclear power plants. Prospects for identifying the occurrence and predicting the extent of deterioration are discussed

  10. 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。

  11. ESTIMATION OF IN-PLACE STRENGTH OF CONCRETE WITH COMBINED NONDESTRUCTIVE METHOD

    OpenAIRE

    İsa YÜKSEL

    2003-01-01

    This paper presents estimation of concrete strength by the SONREB method that is a combined non-destructive testing method and application of the method on a reinforced concrete building structure. Comparison of results of both destructive and non-destructive test results is introduced also. The SONREB method is based on evaluation of the combination of Schmidt hammer readings and ultrasonic pulse velocity measurements. The measured material properties are correlated with compressive strength...

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

    OpenAIRE

    Al Shamaa, Mohamad

    2012-01-01

    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 i...

  13. 29 CFR 1926.703 - Requirements for cast-in-place concrete.

    Science.gov (United States)

    2010-07-01

    ... members have been designed for such loading. (8) Whenever single post shores are used one on top of... plumbness during the jacking operation. (7) The predetermined safe rate of lift shall not be exceeded. (d... capable of supporting without failure all vertical and lateral loads that may reasonably be anticipated...

  14. 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...

  15. Efficiency study of superplasticizers to ensure durability of concrete placed by pump.

    OpenAIRE

    Kodelja, Matej

    2009-01-01

    Production of contemporary, high-performance concrete is almost impossible without chemical admixtures, particularly when plastic concrete is placed by pump or when adequate consistency has to be kept from manufacturing to placing of concrete in most environmental conditions. This was the starting point of my diploma work: to choose a chemical admixture - superplasticizer that will be sufficiently effective, practical to use and compatible with available basic materials. I obtained the basic ...

  16. 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...

  17. Resistance to fatigue and prediction of lifetime of wire tendons cast into concrete up to 10^8 cycles

    OpenAIRE

    Heinrich, Jens; Heeke, Guido; Maurer, Reinhard; Müller, Christine H.

    2016-01-01

    Usually for verification of compliance, the fatigue resistance of prestressing steel is determined from tests of naked specimens at 2 million cycles. However, for design the fatigue resistance of tendons cast into concrete, is substantially lower. To verify the resistance of existing older prestressed concrete bridges and for the design of new bridges, S-N curves of prestressing steel in curved steel ducts embedded into concrete are needed. In bridges, the load cycles due to heavy...

  18. Important Tenders and Contracts to be Placed in the Near Future - Concrete and Masonry Construction Work for the Control Station and Part of the Annex Laboratory Wing and the Corridor which Connects them to the Main SC Building

    CERN Document Server

    European Organization for Nuclear Research

    1955-01-01

    Important Tenders and Contracts to be Placed in the Near Future - Concrete and Masonry Construction Work for the Control Station and Part of the Annex Laboratory Wing and the Corridor which Connects them to the Main SC Building

  19. Variability in properties of Salado Mass Concrete

    International Nuclear Information System (INIS)

    Salado Mass Concrete (SMC) has been developed for use as a seal component in the Waste Isolation Pilot Plant. This concrete is intended to be mixed from pre-bagged materials, have an initial slump of 10 in., and remain pumpable and placeable for two hours after mixing. It is a mass concrete because it will be placed in monoliths large enough that the heat generated during cement hydration has the potential to cause thermal expansion and subsequent cracking, a phenomenon to avoid in the seal system. This report describes effects on concrete properties of changes in ratio of water to cement, batch size, and variations in characteristics of different lots of individual components of the concrete. The research demonstrates that the concrete can be prepared from laboratory-batched or pre-bagged dry materials in batches from 1.5 ft3 to 5.0 yd3, with no chemical admixtures other than the sodium chloride added to improve bonding with the host rock, at a water-to-cement ratio ranging from 0.36 to 0.42. All batches prepared according to established procedures had adequate workability for at least 1.5 hours, and achieved or exceeded the target compressive strength of 4500 psi at 180 days after casting. Portland cement and fly ash from different lots or sources did not have a measurable effect on concrete properties, but variations in a shrinkage-compensating cement used as a component of the concrete did appear to affect workability. A low initial temperature and the water-reducing and set-retarding functions of the salt are critical to meeting target properties

  20. SIMULATION MODELS OF RESISTANCE TO CONCRETE MOVEMENT IN THE CONCRETE CONVEYING PIPE OF THE AUTOCONCRETE PUMP

    OpenAIRE

    P. G. Anofriev

    2015-01-01

    Purpose. In modern construction the placing of concrete is often performed using distribution equipment of concrete pumps. Increase of productivity and quality of this construction work requires improvement of both concrete pumps and their tooling. The concrete pumps tooling consists of standardized concrete conveying pipes and connector bends radius of up to 2 m. A promising direction of tooling improvement is the reduce of resistance to movement of the concrete in the concrete conveying pip...

  1. 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.

  2. Studies of the transition zone in steel – chromium cast iron bimetallic casting

    Directory of Open Access Journals (Sweden)

    S. Tenerowicz

    2010-01-01

    Full Text Available In this work authors presented the results of transition zone studies on steel – cast iron interface in bimetallic casting. During the investigations cylindrical castings with different diameter were prepared of cast iron with steel rods placed in the center. From each bimetallic casting a microsection was prepared for microhardness tests and metalographic analysis, consisting of transition zone measurement, point and linear analysis as well as quantitative analysis.

  3. 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

    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...... 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...... 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 as...

  4. 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...

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

    DEFF Research Database (Denmark)

    Pedersen, Troels Holm; Lenau, Torben Anker

    2010-01-01

    that are rich in detail. Variable geometry moulds (VGM) offer a different approach to small production volume. A die or mould can change shape between the castings, and parts with different geometry can be made in the same mould. VGM is used in a multitude of applications such as sheet metal forming of parts...... for aircrafts, trains and cranial prostheses. The present project focuses on VGM for free form concrete facade elements, which in contrast to previous VGM projects uses a liquid raw material and involves the use of only a small amount of force. Method of Approach: The present VGM process is based on the so...

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

    DEFF Research Database (Denmark)

    Egholm Pedersen, Ole

    2012-01-01

    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...... 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 and......: 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, the...

  7. Casting in Sport

    OpenAIRE

    DeCarlo, Mark; Malone, Kathy; Darmelio, John; Rettig, Arthur

    1994-01-01

    Attempts by sports medicine professionals to return high school athletes with hand and wrist injuries to competition quickly and safely have been the source of confusion and debate on many playing fields around the country. In addition to the differing views regarding the appropriateness of playing cast usage in high school football, a debate exists among sports medicine professionals as to which material is best suited for playing cast construction. Materials used in playing cast constructio...

  8. 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.

  9. 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.

  10. Casting defects in low-pressure die-cast aluminum alloy wheels

    Science.gov (United States)

    Zhang, B.; Cockcroft, S. L.; Maijer, D. M.; Zhu, J. D.; Phillion, A. B.

    2005-11-01

    Defects in automotive aluminum alloy casting continue to challenge metallurgists and production engineers as greater emphasis is placed on product quality and production cost. A range of casting-related defects found in low-pressure die-cast aluminum wheels were examined metallographically in samples taken from several industrial wheel-casting facilities. The defects examined include macro- and micro- porosity, entrained oxide films, and exogenous oxide inclusions. Particular emphasis is placed on the impact of these defects with respect to the three main casting-related criteria by which automotive wheel quality are judged: wheel cosmetics, air-tightness, and wheel mechanical performance.

  11. Diagnosing delayed ettringite formation in concrete structures

    International Nuclear Information System (INIS)

    There has been a number of cases involving deteriorated concrete structures in North America where there has been considerable controversy surrounding the respective contributions of alkali-silica reaction (ASR) and delayed ettringite formation (DEF) to the observed damage. The problem arises because the macroscopic symptoms of distress are not unequivocal and microscopical examinations of field samples often reveal evidence of both processes making it difficult to separate the individual contributions. This paper presents the results of an investigation of a number of concrete columns carrying a raised expressway in North America; prior studies had implicated both DEF and ASR as possible causes of deterioration. Although the columns were not deliberately heat-cured, it is estimated that the peak internal temperature would have exceeded 70 deg. C and perhaps even 80 deg. C, in some cases. The forensic investigation included scanning electron microscopy with energy-dispersive X-ray analysis and expansion testing of cores extracted from the structure. Small-diameter cores stored in limewater expanded significantly (0.3 to 1.3%) and on the basis of supplementary tests on laboratory-produced concrete specimens it was concluded that expansion under such conditions is caused by DEF as the conditions of the test will not sustain ASR. In at least one column, DEF was diagnosed as the sole contributory cause of damage with no evidence of any contribution from ASR or any other deterioration process. In other cases, both ASR and DEF were observed to have contributed to the apparent damage. Of the columns examined, only concrete containing fly ash appeared to be undamaged. The results of this study confirm that, under certain conditions, the process of DEF (acting in isolation of other processes) can result in significant deterioration of cast-in-place reinforced concrete structures

  12. Casting in sport.

    Science.gov (United States)

    Decarlo, M; Malone, K; Darmelio, J; Rettig, A

    1994-03-01

    Attempts by sports medicine professionals to return high school athletes with hand and wrist injuries to competition quickly and safely have been the source of confusion and debate on many playing fields around the country. In addition to the differing views regarding the appropriateness of playing cast usage in high school football, a debate exists among sports medicine professionals as to which material is best suited for playing cast construction. Materials used in playing cast construction should be hard enough to provide sufficient stabilization to the injured area and include adequate padding to absorb blunt impact forces. The purpose of the biomechanical portion of this investigation was to attempt to determine the most appropriate materials for use in constructing playing casts for the hand and wrist by assessing different materials for: 1) hardness using a Shore durometer, and 2) ability to absorb impact using a force platform. Results revealed that RTV11 and Scotchcast were the "least hard" of the underlying casting materials and that Temper Stick foam greatly increased the ability of RTV11 to absorb impact. Assessment of the mechanical properties of playing cast materials and review of current developments in high school football rules are used to aid practitioners in choosing the most appropriate materials for playing cast construction. PMID:16558257

  13. a Study on Improvement and its Evaluation for the Surface Layer of Concrete Placed with Permeable Form

    Science.gov (United States)

    Tanaka, Ryoichi; Habuchi, Takashi; Amino, Takahiko; Fukute, Tsutomu

    Permeable form can improve the quality of the surface layer of concrete and can enhance the durability of concrete structures. In this study, the improvement and its evaluation for the surface layer of concrete placed with permeable form were investigated. For these purposes, accelerated carbonation test, chloride ion penetration test, air permeability test, rebound hummer test and water permeability test were conducted using the concrete specimen. As a result, it was found that the air permeability correlates the carbonation depth, chloride ion penetration depth, rebound number and water permeable volume of concrete. Moreover, the possibility that the improvement for the surface layer of concrete can be quantitatively evaluated by air permeability test was shown.

  14. 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

  15. Lean duplex stainless steels—The role of molybdenum in pitting corrosion of concrete reinforcement studied with industrial and laboratory castings

    International Nuclear Information System (INIS)

    Highlights: ► Mo influence on corrosion of DSS was studied with industrial and laboratory heats. ► Beneficial effect of Mo was associated with ferrite corrosion resistance. ► Mo-species in the alkaline solution did not improve pit resistance. ► Mo role in DSS under alkaline conditions was ascribed to its presence in oxide film. - Abstract: The influence of Mo addition on pitting corrosion resistance of lean duplex stainless steels is not clearly understood in alkaline chloride conditions even if this element is widely recognized to increase corrosion resistance in acidic and neutral environments. This work aims to study the effect of Mo on pitting corrosion of lean duplex stainless steels in synthetic concrete pore solutions simulating degraded concrete. Results are discussed with respect to the influence of Mo on pitting potential for two industrial alloys in chloride rich and carbonated solution simulating concrete pore environments. To establish the real effect of Mo addition on lean duplex corrosion and passivation properties, two specific laboratory lean duplex alloys, for which the only difference is strictly the Mo content, are also studied. Mo presented a strong positive influence on the pitting corrosion resistance of industrial and laboratory lean duplex stainless steels in all studied chloride-rich solutions, but its effect is as less pronounced as the pH increases. In presence of Mo, pitting initiates and propagates preferentially in the austenitic phase at high temperature.

  16. Bainite obtaining in cast iron with carbides castings

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2010-01-01

    Full Text Available In these paper the possibility of upper and lower bainite obtaining in cast iron with carbides castings are presented. Conditions, when in cast iron with carbides castings during continuous free air cooling austenite transformation to upper bainite or its mixture with lower bainte proceeds, have been given. A mechanism of this transformation has been given, Si, Ni, Mn and Mo distribution in the eutectic cell has been tested and hardness of tested castings has been determined.

  17. Morphology and mechanical behaviour of concretes reinforced by amorphous cast fibres

    International Nuclear Information System (INIS)

    This research thesis addresses the characterization of the morphology and mechanical behaviour of concretes reinforced by amorphous cast fibres. It first gathers some general characteristics and observations related to the amorphous cast fibre: roughness, failure mode, amorphous structure, X-ray analysis, fire resistance. Experimental methods and techniques developed for morphological analysis and mechanical tests are presented (sample preparation, tensile test, and compression sample) and the use of image automatic analysis techniques is then addressed (void morphology and granulometry analysis, inter-void distance measurement, fibre spatial distribution). The next part reports the study of the mechanical behaviour under axial compression

  18. 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

  19. Recommendation of RILEM TC 178-TMC: Testing and modelling chloride penetration in concrete

    OpenAIRE

    Vennesland, Øystein; Climent Llorca, Miguel Ángel; Andrade, Carmen

    2013-01-01

    This RILEM Technical Recommendation intends to give a general description of methods of sampling for obtaining chloride concentration profiles in concrete, applicable both for laboratory cast concrete specimens, for concrete cores taken from structures and for testing on site. These sampling procedures may be applied for obtaining concentration profiles of any other chemical species present in concrete.

  20. 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.

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

    OpenAIRE

    Jong-Sup Park; Young Jin Kim; Jeong-Rae Cho; Se-Jin Jeon

    2015-01-01

    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 ...

  2. 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.

  3. 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。

  4. 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.

  5. Detecting the Presence of High Water-to-Cement Ratio in Concrete Surfaces Using Highly Nonlinear Solitary Waves

    Directory of Open Access Journals (Sweden)

    Piervincenzo Rizzo

    2016-04-01

    Full Text Available We describe a nondestructive evaluation (NDE method based on the propagation of highly nonlinear solitary waves (HNSWs to determine the excess of water on the surface of existing concrete structures. HNSWs are induced in a one-dimensional granular chain placed in contact with the concrete to be tested. The chain is part of a built-in transducer designed and assembled to exploit the dynamic interaction between the particles and the concrete. The hypothesis is that the interaction depends on the stiffness of the concrete and influences the time-of-flight of the solitary pulse reflected at the transducer/concrete interface. Two sets of experiments were conducted. In the first set, eighteen concrete cylinders with different water-to-cement (w/c ratios were cast and tested in order to obtain baseline data to link the ratio to the time of flight. Then, sixteen short beams with fixed w/c ratio, but subject to water in excess at one surface, were cast. The novel NDE method was applied along with the conventional ultrasonic pulse velocity technique in order to determine advantages and limitations of the proposed approach. The results show that the time of flight detected the excess of water in the beams. In the future, the proposed method may be employed in the field to evaluate rapidly and reliably the condition of existing concrete structures and, in particular, concrete decks.

  6. 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.

  7. 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...... mixtures are tested 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 water absorption in fresh concrete and without extra water, the internal curing water held by SAP may...... contribute to increase the degree of hydration. No matter if SAP is added with or without extra water, it appears that the so-called gel space ratio can be used as a key parameter to link age and mixture proportions (water-to-cement ratio and SAP dosage) to the resulting chloride migration coefficient; the...

  8. 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.

  9. ADVANCEMENTS IN CONCRETE TECHNOLOGY

    OpenAIRE

    Shri Purvansh B. Shah; Shri Prakash D. Gohil; Shri Hiren J. Chavda; Shri Tejas D. Khediya

    2015-01-01

    Developing and maintaining world’s infrastructure to meet the future needs of industrialized and developing countries is necessary to economically grow and improve the quality of life. The quality and performance of concrete plays a key role for most of infrastructure including commercial, industrial, residential and military structures, dams, power plants. Concrete is the single largest manufactured material in the world and accounts for more than 6 billion metric tons of materials annual...

  10. 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.

  11. Place Branding in Systems of Place

    DEFF Research Database (Denmark)

    Zenker, Sebastian; Andéhn, Mikael

    2015-01-01

    The pervasive managerial logic of branding has established a stable foothold in the context of place management. Yet the question of whether places, such as cities, regions and nations, can be effectively managed using marketing techniques remains elusive, as place brands and company brands have...... – like a city, region or nation brand – is per definition attached to a system of geographical abstractions in quasi-cartographic form in which each city, region or nation is understood in relation and contrast to other geographical entities. For those who seek to alter perceptions about a place.......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...

  12. 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.

  13. Glazed Concrete

    DEFF Research Database (Denmark)

    Bache, Anja Margrethe

    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 is the...... 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....

  14. 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...

  15. 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...

  16. Application of nanotechnology in self-compacting concrete design

    International Nuclear Information System (INIS)

    In this study, first, different mix design of four types of Self-Compacting Concrete, 1. Self-Compacting Concrete consisted of only nano silica, 2. Self-Compacting Concrete included only micro silica, 3. Self-Compacting Concrete consisted of both micro silica and nano silica and 4. Self-Compacting Concrete without micro silica and nano silica called as control mix, were casted and tested to find out the values of the Slump Flow, L-Box and 7 and 28 days compressive strength. Then, based on the results obtained and as yet there is no universally accepted standard for characterizing of Self-Compacting Concrete, the most suitable four concrete mixes were selected for further investigation of fresh and hardened concrete. For selected mixes, the fresh concrete properties such as values of the Slump Flow, L-Box, V-Funnel, J-Ring and hardened engineering properties such as compressive and flexural strength, shrinkage and swelling values were investigated for three curing conditions at short and long term. The results showed that the engineering properties of Self-Compacting Concrete mixes could not be improved by adding only nano silica. However, a satisfactory behavior can be achieved using micro silica in the Self-Compacting Concrete mixes. However, by adding both micro silica and nano silica to the Self-Compacting Concrete mixtures, the best effect on the engineering properties was reported while comparing to the control mixes.

  17. How to monitor the modulus of elasticity of concrete, automatically since the earliest age?

    OpenAIRE

    Boulay, Claude; Staquet, Stéphanie; DELSAUTE, Brice; CARETTE, Jérôme; Crespini, Michela; YAZOGHLI MARZOUK, O; MERLIOT, Érick; RAMANICH, Sandrine

    2014-01-01

    Monitoring the evolution of an early age set of parameters on concrete is necessary to predict the early age behaviour of structures. The difficulty lies in the fact that this monitoring must be automatic because the concrete hardening process takes place over a long period after the casting. This paper presents a new methodology and an apparatus, specifically designed at IFSTTAR, to monitor the hardening process of a concrete. Mainly, the Young's modulus can be monitored in compression. M...

  18. Field application of self-healing concrete with natural fibres as linings for irrigation canals in Ecuador

    OpenAIRE

    Sierra Beltran, M.G.; Jonkers, H.M.; Mors, R.M.; Mera-Ortiz, W.

    2015-01-01

    This paper describes the first field application of self-healing concrete with alkaliphilic spore-forming bacteria and reinforced with natural fibres. The application took place in the highlands in Ecuador in July 2014. The concrete was cast as linings for an irrigation canal that transports water from glaciers in the Andean mountains to agricultural fields. This canal has been used for over a century by the local farmers. Until not long ago the walls and bottom of the canals were simply made...

  19. 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.

  20. Advances in polymer concrete technology for cell house components

    International Nuclear Information System (INIS)

    The cell house environment is very challenging with regard to protection of the concrete structure and components against the corrosive effects of acid. Coating technology using Epoxy, Vinyl Ester and Polyurethane Polymers is available, to provide the necessary chemical and heat resistance. However, producing suitable POLYMER CONCRETE technology for pre-cast components, especially tanks and cells requires not only the correct POLYMER selection, but also significant know-how in mineral aggregate technology to achieve the desired performance properties. Furthermore, the POLYMER CONCRETE technology must enable the pre-caster to manufacture the components in a simple one-step procedure. This paper outlines the important aspects in formulating POLYMER CONCRETE, the performance properties that can be achieved and the practical issues relating to the cost effective pre-casting of tanks and cells in particular. (author)

  1. 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.

  2. 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...

  3. Hair casts

    Directory of Open Access Journals (Sweden)

    Sweta S Parmar

    2014-01-01

    Full Text Available Hair casts or pseudonits are circumferential concretions,which cover the hair shaft in such a way that, it could be easily removed. They are thin, cylindrical, and elongated in length. We present an unusual case of an 8-year-old girl presenting with hair casts. Occurrence of these is unusual, and they may have varied associations. This patient was suffering from developmental delay. It is commonly misdiagnosed as and very important to differentiate from pediculosis capitis.

  4. 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)

  5. 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…

  6. Mathematical Modelling of the Thermical Regime in the Continous Casting Process

    OpenAIRE

    Monika Erika POPA; Kiss, Imre

    2005-01-01

    Continuous casting is one of the prominent methods of production of casts. Effective design and operation of continuous casting machines needs complete analysis of the continuous casting process. In this paper the basic principles of continuous casting and its heat transfer analysis using the finite element method are presented. In the analysis phase change is assumed to take place at constant temperature. A front tracking algorithm has been developed to predict the position of the solidifica...

  7. 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...

  8. 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

  9. Sodium Exposure Tests on Limestone Concrete Used as Sacrificial Protection Layer in FBR

    International Nuclear Information System (INIS)

    Hot sodium coming in contact with structural concrete in case of sodium leak in FBR system cause damage as a result of thermo-chemical attack by burning sodium. In addition, release of free and bound water from concrete leads to generation of hydrogen gas, which is explosive in nature. Hence limestone concrete, as sacrificial layer on the structural concrete in FBR, needs to be qualified. Four concrete blocks of dimension 600 mm x 600 mm x 300 mm with 300 mm x 300 mm x 150 mm cavity were cast and subjected to controlled sodium exposure tests. They have composition of ordinary portland cement, water, fine and coarse aggregate of limestone in the ratio of 1: 0.58: 2.547: 3.817. These blocks were subjected to preliminary inspection by ultrasonic pulse velocity technique and rebound hammer tests. Each block was exposed for 30 minutes to about 12 kg of liquid sodium (∼ 120 mm liquid column) at 550 deg. C in open air, after which sodium was sucked back from the cavity of the concrete block into a sodium tank. On-line temperature monitoring was carried out at strategic locations of sodium pool and concrete block. After removing sodium from the cavity and cleaning the surfaces, rebound hammer testing was carried out on each concrete block at the same locations where data were taken earlier at pre-exposed stage. The statistical analysis of rebound hammer data revealed that one of the concrete block alone has undergone damage to the extent of 16%. The loss of mass occurred for all the four blocks varied from 0.6 to 2.4% due to release of water during the test duration. Chemical analysis of sodium in concrete samples collected from cavity floor of each block helped in generation of depth profiles of sodium monoxide concentration for each block. From this it is concluded that a bulk penetration of sodium up to 30 mm depth has taken place. However it was also observed that at few local spots, sodium penetrated into concrete up to 50 mm. Cylindrical core samples of 50 mm x 150

  10. 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.

  11. Models of transport processes in concrete

    International Nuclear Information System (INIS)

    An approach being considered by the US Nuclear Regulatory Commission for disposal of low-level radioactive waste is to place the waste forms in concrete vaults buried underground. The vaults would need a service life of 500 years. Approaches for predicting the service life of concrete of such vaults include the use of mathematical models. Mathematical models are presented in this report for the major degradation processes anticipated for the concrete vaults, which are corrosion of steel reinforcement, sulfate attack, acid attack, and leaching. The models mathematically represent rate controlling processes including diffusion, convection, and reaction and sorption of chemical species. These models can form the basis for predicting the life of concrete under in-service conditions. 33 refs., 6 figs., 7 tabs

  12. Drying of Concrete

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard; Geiker, Mette Rica; Nygaard, Peter Vagn; Kjeldsen, Ane Mette

    Estimated and measured relative humidity (RH) change during drying are compared for two concretes, 1: w/c=0.46 and 2: w/(c+0.5fa+2sf)=0.50. The estimations were undertaken by means of the Swedish program TorkaS 1.0. Measurements were performed by RH-sensors type Humi-Guard. Drying of 150 mm thick...... samples from sides at 60% RH and 22 °C took place from 4 to 56 days after casting. At the end of the drying period the measured RH was about 4% lower than the estimated RH at 1/5th depth from the exposed surface for both concretes. In the middle of the samples, the measured RH of concretes 1 and 2 were 2...

  13. 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.

  14. 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.

  15. Stay-In Place Deck Panels - Part 1

    OpenAIRE

    Goldman, Ariel; Cohen, Menashi D.; Ramirez, J A

    1995-01-01

    The objective of this study was the evaluation of frost resistance of concrete bridge decks with stay-in-place galvanized steel deck forms. The evaluation included specific aspects related to the potential for D-cracking in concrete bridge decks with these forms. The experimental program has been set up so that the real parameters of the bridge deck overlays and the environmental conditions could have been modeled. The program included freezing-and-thawing testing of large concrete slab speci...

  16. 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...

  17. 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...... how 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...

  18. 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。

  19. 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.e. in...

  20. 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.

  1. Comparative Study of Effect of Sustained High Temperature on strength Properties of Self Compacting Concrete and Ordinary Conventional Concrete

    Directory of Open Access Journals (Sweden)

    D. B. Kulkarni,

    2011-04-01

    Full Text Available Self Compacting Concrete is a material used in the construction where it is suitable for placing the concrete in difficult conditions and in structures with congested reinforcement without vibration. In case of unexpected fire, the concrete elements such as beams, columns etc will be subjected to extreme temperatures and need for assessment of their performance after fire. Hence, it is important to understand the change in the concrete strength properties due to extreme temperature exposure. This paper presents an assessment of effect of sustained temperatures on strength properties of self compacting concrete and its comparison with ordinary Conventional Concrete. In order to study effect of sustained elevated temperature on the compressive strength, flexural strength, tensile strength & impact strength of self compacting concrete and ordinary concrete, the specimens of Self Compacting Concrete and ordinary conventional concrete were tasted in laboratory. For various tests 21 cubes(150mmX150mmX150mm, 21 cylinders (100mmdiaX200mmheight, 21 beams(100mmx100mmX500mm and 21 plates were cast and same for the ordinary concrete. The specimens were kept in oven at required temperature ( 280C, 1000C, 2000C, 3000C,4000C,5000C and 6000C for 5 hrs at constant temperatures. The results obtained were compared with the corresponding properties of normal concrete with the same water cement and air content.

  2. Concrete Sawing Waste Recycling As Microfiller in Concrete Production

    OpenAIRE

    Bumanis, G.; Shakhmenko, G.; Kara, P; Korjakins, A.

    2015-01-01

    The main idea of the presented work is to find the ways of recycling the sawing waste/sludge in production of the new concrete. The aim of the study is to examine application of the dust-water suspension as micro filler in self-compacting concrete. In the process of sawing concrete elements a lot of dust waste is produced, the average amount being approximately 0.5-1% of the total amount of concrete. To avoid dust pollution in a production plant the sawing process is accompanied by a water st...

  3. 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.

  4. 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.)

  5. 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...

  6. 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

  7. 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...

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

    DEFF Research Database (Denmark)

    Blaakilde, Anne Leonora

    2015-01-01

    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 is...... 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....

  9. 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...

  10. Pressure distribution in centrifugal dental casting.

    Science.gov (United States)

    Nielsen, J P

    1978-02-01

    Equations are developed for liquid metal pressure in centrifugal dental casting, given the instantaneous rotational velocity, density, and certain dimensions of the casting machine and casting pattern. A "reference parabola" is introduced making the fluid pressure concept more understandable. A specially designed specimen demonstrates experimentally the reference parabola at freezing. PMID:355283

  11. Egg Shell As A Fine Aggregate In Concrete For Sustainable Construction

    Directory of Open Access Journals (Sweden)

    S.A. Raji

    2015-08-01

    Full Text Available ABSTRACT This work has investigated the potential use of usedegg shell as a concrete material. The usedegg shells were used as fine concrete aggregate. In the laboratory test conventional fine aggregate was replaced at 100 replacement level. A total of 18 cubes were cast cured and tested. The strength development of the concrete mixes containing egg shell aggregates was compared to that of conventional concrete with sand as fine aggregate. The result showed a reduction in compressive strength of the concrete but still falls within limits of lightweight concrete. This paper recommends that egg shell can be used for producing concrete where a lighter weight concrete is required and a reduction of dead load of structure is desired.

  12. Casting behavior of titanium alloys in a centrifugal casting machine.

    Science.gov (United States)

    Watanabe, K; Miyakawa, O; Takada, Y; Okuno, O; Okabe, T

    2003-05-01

    Since dental casting requires replication of complex shapes with great accuracy, this study examined how well some commercial titanium alloys and experimental titanium-copper alloys filled a mold cavity. The metals examined were three types of commercial dental titanium [commercially pure titanium (hereinafter noted as CP-Ti), Ti-6Al-4V (T64) and Ti-6Al-7Nb (T67)], and experimental titanium-copper alloys [3%, 5% and 10% Cu (mass %)]. The volume percentage filling the cavity was evaluated in castings prepared in a very thin perforated sheet pattern and cast in a centrifugal casting machine. The flow behavior of the molten metal was also examined using a so-called "tracer element technique." The amounts of CP-Ti and all the Ti-Cu alloys filling the cavity were similar; less T64 and T67 filled the cavity. However, the Ti-Cu alloys failed to reach the end of the cavities due to a lower fluidity compared to the other metals. A mold prepared with specially designed perforated sheets was effective at differentiating the flow behavior of the metals tested. The present technique also revealed that the more viscous Ti-Cu alloys with a wide freezing range failed to sequentially flow to the end of the cavity. PMID:12593955

  13. Quality Control of Concrete Structure For APR1400 Construction

    International Nuclear Information System (INIS)

    Nuclear structure shall be constructed to protect internal facilities in the normal operation against external accidents such as the radiation shielding, earthquakes and to be leak-proof of radioactive substances to the external environment in case of loss of coolants. containment and auxiliary building of nuclear power plants are built in reinforced concrete structures to maintain these protection functions. Nuclear structures shall be designed to ensure soundness in operation since they are located on the waterfront where is easy do drain the cooling water and so deterioration and damage of concrete structures caused by seawater can occur. Durability is ensured for concrete structures of APR1400, a Korea standard NPP, in compliance with all safety requirements. In particular, owners perform quality control directly on the production and pouring of cast in place concrete for the concrete structure construction to make sure concrete structures established with quality homogeneity and durability. This report is to look into the quality control standard and management status of cast in place concrete for APR1400 construction

  14. 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

  15. Strangers in Familiar Places

    DEFF Research Database (Denmark)

    Muhr, Sara Louise

    2012-01-01

    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......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...... – 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....

  16. Expansion of Hanford concrete

    International Nuclear Information System (INIS)

    This report presents results of measurements of thermal expansion of concrete cores from Hanford, Washington facilities, and concrete cast at the Construction Technology Laboratories of Portland Cement Association (CTL/PCA). Thermal expansion was measured from room temperature to 16000F on 0.5 x 3.0-in. specimens heated at a rate of 100F/min. Specimens were cored from concrete cylinders cast at CTL/PCA in 1975 and 1977, and from cylindrical cores taken from the Purex Building and Waste Tank Farms at the Hanford, Washington complex. A total of 14 specimens were tested: eight tests on CTL/PCA cast concrete, two tests on material from the Purex Building, and four tests on Waste Tank Farms concrete. All tests were conducted using a commercially built dilatometer of high strain resolution

  17. Bond of Reinforcement in Concrete Applied to Concrete Quality Control: The Bottle Bond Test

    OpenAIRE

    García Taengua, Emilio José; Martí Vargas, José Rocío; Serna Ros, Pedro

    2014-01-01

    This paper presents the results of an experimental research dealing with bond strength as a parameter for concrete quality control. To this end, a low-cost testing technique has been developed: the Bottle Bond Test (BBT). Specimens for the BBT are produced by casting concrete into empty plastic bottles (used as moulds) with a reinforcing bar longitudinally centred. The result is a bottle-shaped concrete specimen with an embedded rebar, which is pulled out to determine bond strength. Different...

  18. DETERMINATION OF FRACTURE PARAMETERS AND THE STUDY OF MIXED MODE CRACK PROPAGATION IN HIGH PERFORMANCE CONCRETE

    Directory of Open Access Journals (Sweden)

    Venkatesh

    2015-08-01

    Full Text Available n th e paper an experime n tal i n ve s tigation was carri ed out to study the Mixed Mode Crack Parameters of High Performance Concrete beams subjected to three point bending . The cubes and cylinders will be tested on Universal Testing Machine to find out the Compressive strength and split tensile strength. For High Performance Concrete, the partial replacement of cement with Grou nd Granulated Blast Furnace Slag (GGBS and sand with the ROBO sand (crusher dust will be taken. In this investigation the study of Mixed Mode Crack Propagation in High Performance Concrete b eams with eccentrically placed notch at a distance (L/4 from mi d span of the beam under a three point bending test i.e., with a central point load will be done. In High Performance Concrete , the Variation of volume fraction s of Ground Granulated Blast furnace Slag (GGBS and ROBO sand in the casting of beams will carr ied out to find the Mixed Mode Fracture Parameters . Fracture parameters like Fracture energy G f , Cohesive fracture process Zone C F , Stress intensity factor K I would be determined by using size effect method.

  19. 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.

  20. 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...

  1. Concrete waterproofing in nuclear industry.

    Science.gov (United States)

    Scherbyna, Alexander N; Urusov, Sergei V

    2005-01-01

    One of the main points of aggregate safety during the transportation and storage of radioactive materials is to supply waterproofing for all constructions having direct contact with radiating substances and providing strength, seismic shielding etc. This is the problem with all waterside structures in nuclear industry and concrete installations in the treatment and storage of radioactive materials. In this connection, the problem of developing efficient techniques both for the repair of operating constructions and the waterproofing of new objects of the specified assignment is genuine. Various techniques of concrete waterproofing are widely applied in the world today. However, in conditions of radiation many of these techniques can bring not a profit but irreparable damage of durability and reliability of a concrete construction; for instance, when waterproofing materials contain organic constituents, polymers etc. Application of new technology or materials in basic construction elements requires in-depth analysis and thorough testing. The price of an error might be very large. A comparative analysis shows that one of the most promising types of waterproofing materials for radiation loaded concrete constructions is "integral capillary systems" (ICS). The tests on radiation, thermal and strength stability of ICS and ICS-treated concrete samples were initiated and fulfilled in RFNC-VNIITF. The main result is--ICS applying is increasing of waterproofing and strength properties of concrete in conditions of readiation The paper is devoted to describing the research strategy, the tests and their results and also to planning of new tests. PMID:16604701

  2. Rapid Drying Concrete

    OpenAIRE

    ECT Team, Purdue

    2015-01-01

    One of the essential problems that are faced during construction is the drying of concrete and the presence of moisture which affects floor coverings that need to be placed. The rapid-drying characteristic in Aridusâ concrete allows for the quick reduction of moisture vapor that travels through the concrete pores of the concrete.

  3. The Tectonic Potentials of Concrete

    DEFF Research Database (Denmark)

    Egholm Pedersen, Ole

    2013-01-01

    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 an...... increased customisation of casting moulds. The hypothesis of this research is that the techniques used in this research do not fully address the tectonic potentials of concrete which gives rise to the primary research question: Is it possible to enhance existing or develop new concrete casting techniques...... which allows for individualisation and resource optimisation, while matching or enhancing the tectonic potentials found in existing, repetitive concrete casting techniques? The research is comprised of two modes of inquiry: an empirical study of contemporary casting methods and subsequently six case...

  4. Drying of concrete. Part I: A comparison of instruments for measuring the relative humidity in concrete structures

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard; Christensen, Søren Lolk

    The paper describes and evaluates five different instruments for measuring the relative humidity (RH) in concrete structures. The instruments work according to different principles. The evaluation of the instruments includes tests for linearity, drift over time, hysteresis and repeatability, and it...... is performed by use of saturated salt solutions in the laboratory. Further, the five different instruments are placed in the same concrete, and the instruments readings are followed during drying of the concrete for 43 days. The laboratory tests and the measurements in the concrete show that most of...... the instruments work well....

  5. The behaviour of concrete structures in fire

    OpenAIRE

    Fletcher, Ian A; Welch, Stephen; Torero, Jose L; Carvel, Ricky O; Usmani, Asif

    2007-01-01

    The nature of concrete-based structures means that they generally perform very well in fire. However, concrete is a complex material and its properties can change dramatically when exposed to high temperatures. This paper provides a ‘state of the art’ review of research into the effects of high temperature on concrete and concrete structures, extending to a range of forms of construction, including novel developments. The principal effects of fire on concrete are loss of compressive strength ...

  6. Self-consolidating concrete homogeneity

    OpenAIRE

    Jarque, J. C.; Parra, C.; Valcuende, M.O.

    2007-01-01

    Concrete instability may lead to the non-uniform distribution of its properties. The homogeneity of self-consolidating concrete in vertically cast members was therefore explored in this study, analyzing both resistance to segregation and pore structure uniformity. To this end, two series of concretes were prepared, self-consolidating and traditional vibrated materials, with different w/c ratios and types of cement. The results showed that selfconsolidating concretes exhibit high resistance to...

  7. 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.

  8. 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.

  9. 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)

  10. 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

  11. 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.

  12. 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

  13. 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

  14. Concrete Thinking

    OpenAIRE

    Kuang-Ming Wu

    2015-01-01

    Existence is concrete discerned bodily, thinking considers existents, and so concrete thinking is primal, at the base of logical thinking. Still, concrete actuality is reasonable beyond logical analysis. So, concrete thinking is “illogical” bodily reasonable. Thus this essay explores 1) concrete thinking various and 2) concrete thinking concretely. All this concrete thinking culminates in kids’ joys alive.

  15. 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...

  16. 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...

  17. High Performance Concrete Pavement in Indiana

    OpenAIRE

    Nantung, Tommy E

    2011-01-01

    Until the early 1990s, curling and warping of Portland cement concrete pavement did not concern pavement engineers in many transportation agencies. Since beginning construction of the interstate system in the United States in the late 1950s through the late 1980s, the performance of Portland cement concrete pavement has been associated with properties of concrete as a pavement material. In those years developed standards and design guidelines emphasized better concrete materials and construct...

  18. 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.

  19. 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...

  20. 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.

  1. 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.

  2. 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.

  3. 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...

  4. Signs in Place

    DEFF Research Database (Denmark)

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

    be an effective guidance tool. However, “signs in place” offer alternative or additional guidelines to help people with their journey. This paper firstly seeks to understand road traffic signs in terms of mobility in everyday life. It then attempts to distinguish the different perspectives of...... mobility 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....

  5. Signs In Place

    DEFF Research Database (Denmark)

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

    2012-01-01

    an effective guidance tool. However, “signs in place” offer alternative or additional guidelines to help people with their journey. This paper, first, seeks to understand road traffic signs in terms of mobility in everyday life. It, then, attempts to distinguish the different perspectives of mobility...... 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...

  6. 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.

  7. DEVELOPMENTS IN THE FIELD OF STEEL AND CAST IRON

    OpenAIRE

    Ten, E. B.; V. D. Belov

    2015-01-01

    The article describes the use of a number of promising casting technologies applied to produce the castings of steel and cast iron with special properties. Such as, technology of centrifugal casting of large-size workpieces made of steel, forecasting method composition of slag in the smelting of high-manganese steels, method of complex modifying chromium cast irons, analysis of properties of perspective high-alloy aluminium cast iron.

  8. DEVELOPMENTS IN THE FIELD OF STEEL AND CAST IRON

    Directory of Open Access Journals (Sweden)

    E. B. Ten

    2015-05-01

    Full Text Available The article describes the use of a number of promising casting technologies applied to produce the castings of steel and cast iron with special properties. Such as, technology of centrifugal casting of large-size workpieces made of steel, forecasting method composition of slag in the smelting of high-manganese steels, method of complex modifying chromium cast irons, analysis of properties of perspective high-alloy aluminium cast iron.

  9. Effects of Concrete on Propagation Characteristics of Guided Wave in Steel Bar Embedded in Concrete

    OpenAIRE

    Zhupeng Zheng; Ying Lei

    2014-01-01

    Techniques based on ultrasonic guided waves (UGWs) play important roles in the structural health monitoring (SHM) of large-scale civil infrastructures. In this paper, dispersion equations of longitudinal wave propagation in reinforced concrete member are investigated for the purpose of monitoring steels embedded in concrete. For a steel bar embedded in concrete, not the velocity but the attenuation dispersion curves will be affected by the concrete. The effects of steel-to-concrete shear modu...

  10. Corrosion of metal materials embedded in concrete

    International Nuclear Information System (INIS)

    Carbon steel is the material most frequently used to strengthen reinforced concrete structures; however, stainless steel and galvanized steel reinforcements are also used in construction concretes; and they are not often used in Latin America. Meanwhile, there are other metals that are embedded in the concrete forming part of the openings (aluminum) or in tubing systems (copper and lead). The use of concrete as a cementing material is also useful for immobilizing wastes, such as for example those generated by the nuclear industry. There is a great deal of research and development on the corrosion of steel reinforcements, but the same is not true for the behavior of other metals embedded in concrete and that also undergo corrosive processes. This work aims to study the corrosion of different metals: copper, lead, aluminum, zinc, stainless steel and carbon steel; embedded in concrete with and without the presence of aggressive species for the metal materials. Test pieces were made of mortar containing rods of different materials for testing, and with chlorides added in concentrations of 0; 0.3 % and 1% (mass of chloride per mass of cement). The test pieces were exposed to different conditions; laboratory environment with a relative humidity (RH) of 45%, a controlled atmosphere with 98% RH and submerged in a solution of 3.5% NaCl. The susceptibility to corrosion of the different metals was evaluated using techniques to monitor the corrosion potential, the resistivity of the mortar and the polarization resistance (PR). The rods were weighed before being placed inside the test pieces to later determine the loss of weight generated by the corrosion process. Polarization curves for the metals were also traced in a simulated pore solution (SPS) and in SPS with added chloride. The results obtained to date show that, of all the metals analyzed, aluminum is the most susceptible to corrosion, and that the test specimens with 0% and 1% of chloride exposed to the laboratory

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Addressing concrete cracking in NPPs

    International Nuclear Information System (INIS)

    The phenomenon of concrete cracking is one of the most frequently encountered deterioration at NPPs as it has been shown by a wide Survey of NPPs performed by IAEA in 1994-95 It can be due to a multitude of causes such as the normal ageing process (shrinkage, creep, prestressing force loss) as well as exposure to the environment (temperature variation, moisture, freeze/thaw, etc) The above mentioned Survey has also shown that in 64% of cases, no action was taken or required. It became also obvious that there is a lack of guidance as when remedial actions are needed. The paper describes, with the help of a Flow Chart, the various stages to be considered, from the first step of identification of cracks, to the definition of causes, evaluation of extent of damage, evaluation of effect/implications (safety, reliability), to the final step of deciding if repair action is required. Finally, based upon a wide literature survey the paper proposes in a Chart format, Criteria for addressing concrete cracks in NPPs., when taking in considerations all these factors. This paper discusses the process which should lead to the selection of an effective repair method and proposes, based upon worldwide standards and literature, criteria which should lead to the decision whether to repair or not concrete cracks, after the cracks have been identified and evaluated, addressing the entire range of aspects involved. (author)

  18. Redistribution of internal forces in composite concrete girders made continuous vs. time

    Directory of Open Access Journals (Sweden)

    Mašović Snežana

    2011-01-01

    Full Text Available Research on the long-term behavior of composite concrete girders made continuous is presented in the paper. Concrete precast element is cracked under construction load. Creep and differential shrinkage of precast and in-situ cast part of the girder also induce stresses in a structure. The subject of this investigation is redistribution of section forces in course of time for concrete girders subjected to change of the structural system. The aim of investigation is to verify design models and analytical procedures by experimental research.

  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

    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 ...

  1. 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…

  2. 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...

  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. Beneficial Role of the Industrial Wastes to Combat Adiabatic Temperature Rise in Massive Concrete

    Science.gov (United States)

    Ashraf, M.; Goyal, A.; Anwar, A. M.; Hattori, K.; Ogata, H.; Guo, S.

    An evaluation was made on the mutual beneficial role of fly ash and ground granulated blast furnace slag in combating adiabatic temperature rise. The experimental program was designed in two stages; the main experiment consisted of two massive concrete specimens with dimensions (50x50x50) cm. In first stage of experiment, an adiabatic rise in temperature of specimens was measured. In second stage, the mechanical properties of massive concrete specimens were measured at the ages of 8, 14, 28, 56 and 91 days. At the age of 91 days, surface core and central cores were extracted from the surface and the central part of massive concrete specimens to determine compressive strength and dynamic modulus of elasticity. In the massive concrete specimen without any additive, the peak temperature noted was 64.5°C at 7th h after casting. While in mineral substituted concrete the maximum adiabatic temperature was 49.6°C at 19th h after casting. Lower rate of temperature rise in mineral substituted concrete has resulted in higher value of ultrasonic pulse velocity and ultimate compressive strength of concrete.

  5. 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....

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

    DEFF Research Database (Denmark)

    Jensen, Poul; Buhr, Birit; Thorborg, Jesper; Hattel, Jesper; Jeppesen, Per; Coff, Niels

    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 be...... 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...

  7. Effect of Some Parameters on the Cast Component Properties in Hot Chamber Die Casting

    Science.gov (United States)

    Singh, Rupinder; Singh, Harvir

    2016-04-01

    Hot chamber die casting process is designed to achieve high dimensional accuracy for small products by forcing molten metal under high pressure into reusable moulds, called dies. The present research work is aimed at study of some parameters (as a case study of spring adjuster) on cast component properties in hot chamber die casting process. Three controllable factors of the hot chamber die casting process (namely: pressure at second phase, metal pouring temperature and die opening time) were studied at three levels each by Taguchi's parametric approach and single-response optimization was conducted to identify the main factors controlling surface hardness, dimensional accuracy and weight of the casting. Castings were produced using aluminium alloy, at recommended parameters through hot chamber die casting process. Analysis shows that in hot chamber die casting process the percentage contribution of second phase pressure, die opening time, metal pouring temperature for surface hardness is 82.48, 9.24 and 6.78 % respectively. While in the case of weight of cast component the contribution of second phase pressure is 94.03 %, followed by metal pouring temperature and die opening time (4.58 and 0.35 % respectively). Further for dimensional accuracy contribution of die opening time is 76.97 %, metal pouring temperature is 20.05 % and second phase pressure is 1.56 %. Confirmation experiments were conducted at an optimal condition showed that the surface hardness, dimensional accuracy and weight of the castings were improved significantly.

  8. 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...... 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 in...

  9. 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...

  10. Solidification Conditions and Microstructure in Continuously Cast Aluminum

    Science.gov (United States)

    Buxmann, K.; Gold, E.

    1982-04-01

    The well-known relationship between cell size or dendrite spacing and local solidification time gives the possibility of calculating the thermal parameters of solidification from the microstructure of the as-cast product. As a basis for such calculations, the dendrite spacing of different aluminum castings (DC cast ingots of different diameters, cast in conventional and electromagnetic molds; cast strip from roll casters, belt casters, and block casters; and Properzi cast rod) has been measured through their cross sections. Based on these measurements, a qualitative discussion of the thermal conditions during the solidification of these products is given, and the influence of a variation in the casting conditions discussed.

  11. Air permeability of joint between existing and newly placed concrete subjected to sustained and repeated tensile stresses

    International Nuclear Information System (INIS)

    Air permeability of joint between new and old concrete under tensile stress is investigated with mechanical properties of joint experimentally. Treatment roughening the joint surface is made by shot blast method and green cut method. Static, sustained and repeated tensile stresses are applied to specimen, respectively. When viewed in terms of the increasing ratio of air permeability coefficient of specimen in loaded condition to that of specimen in unloaded condition, the increasing ratio for joint is larger compared to that for concrete without joint. Changes in air permeability coefficient and elastic modulus of joint subjected to repeated tensile stress are related to each other by defect rate.(author)

  12. 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

  13. Durability of concrete materials in high-magnesium brine

    Energy Technology Data Exchange (ETDEWEB)

    Wakeley, L.D.; Poole, T.S.; Burkes, J.P. [Army Engineer Waterways Experiment Station, Vicksburg, MS (United States). Structures Lab.

    1994-03-01

    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.

  14. 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...

  15. 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...

  16. 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 ...

  17. 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.

  18. 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

  19. 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 ...

  20. Concept of Place in Novel

    Directory of Open Access Journals (Sweden)

    Mehmet Bakır ŞENGÜL

    2010-04-01

    Full Text Available Novel, as the modern time’s narration type, is a literary type which claims to surround life holistically. It expresses a perception which owns the whole emotions that people have and a perception which focuses on the story of time and individual. Whether it is real or fictional, a person or another object needs place in order to exist. It is seen that ‘place’ starts to gain meaning in people’s mind with the help of the occurrence of the humanity norms and with the help of their perception. The concept of place starts to occupy an important place in novel by following a proper route in accordance with the novel’s development process. The fact that ‘place’ is the basic element of novel has both provided the novel to get away from a character that is only based on the event and both provided its personal side that is to be discovered. The parallelism between the existence of the ‘place’ and the people’s life reflects into the novel in different types. Sometime it is a talky witness of the novel and sometimes it is in place of an actor who displays the physical and spiritual limits of the character of the novel. In this study, the ambiguities which the concept of place has had in the historical process and the forms of the expression of ‘place’ in the prenovel narrations and in the novels have been emphasized.

  1. 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)

  2. 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.

  3. 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...

  4. Modelling reinforcement corrosion in concrete

    DEFF Research Database (Denmark)

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

    2012-01-01

    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......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...

  5. 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

  6. Open to a Changing World: Concrete Poetry in Denmark

    DEFF Research Database (Denmark)

    Ørum, Tania

    The essay describes the rise of concrete poetry in Denmark in the 1960s, the intermedial roots of concrete poetry, concrete poetry as open work (in Eco's sense), the main Danish poets, the development of concrete poetry into systemic writing and the longer cultural perspectives of concrete poetry...

  7. 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

  8. 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.

  9. 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.

  10. Pull-Out Strength and Bond Behavior of Prestressing Strands in Prestressed Self-Consolidating Concrete

    Directory of Open Access Journals (Sweden)

    Wu-Jian Long

    2014-10-01

    Full Text Available With the extensive use of self-consolidating concrete (SCC worldwide, it is important to ensure that such concrete can secure uniform in-situ mechanical properties that are similar to those obtained with properly consolidated concrete of conventional fluidity. Ensuring proper stability of SCC is essential to enhance the uniformity of in-situ mechanical properties, including bond to embedded reinforcement, which is critical for structural engineers considering the specification of SCC for prestressed applications. In this investigation, Six wall elements measuring 1540 mm × 2150 mm × 200 mm were cast using five SCC mixtures and one reference high-performance concrete (HPC of normal consistency to evaluate the uniformity of bond strength between prestressing strands and concrete as well as the distribution of compressive strength obtained from cores along wall elements. The evaluated SCC mixtures used for casting wall elements were proportioned to achieve a slump flow consistency of 680 ± 15 mm and minimum caisson filling capacity of 80%, and visual stability index of 0.5 to 1. Given the spreads in viscosity and static stability of the SCC mixtures, the five wall elements exhibited different levels of homogeneity in in-situ compressive strength and pull-out bond strength. Test results also indicate that despite the high fluidity of SCC, stable concrete can lead to more homogenous in-situ properties than HPC of normal consistency subjected to mechanical vibration.

  11. 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.

  12. Variation of Shrinkage Strain within the Depth of Concrete Beams

    OpenAIRE

    Jong-Hyun Jeong; Yeong-Seong Park; Yong-Hak Lee

    2015-01-01

    The variation of shrinkage strain within beam depth was examined through four series of time-dependent laboratory experiments on unreinforced concrete beam specimens. Two types of beam specimens, horizontally cast and vertically cast, were tested; shrinkage variation was observed in the horizontally cast specimens. This indicated that the shrinkage variation within the beam depth was due to water bleeding and tamping during the placement of the fresh concrete. Shrinkage strains were measured ...

  13. Polymer concrete cell applications in zinc electrowinning

    International Nuclear Information System (INIS)

    The use of polymer concrete cells in zinc electrowinning plants is discussed and the properties of these cells are described. These include, improved corrosion resistance, modularization, maintenance reduction and integrated designs and attachments for bus bars and walkways and for solution handling. Use of UNICELL polymer concrete cells in different cell houses is reviewed. (author)

  14. The long-term properties of concrete used in prestressed concrete pressure vessels

    International Nuclear Information System (INIS)

    Data are presented on the late-life properties of concretes used in prestressed concrete pressure vessels (PCPV) and containment structures. The effects of ageing under simulated PCPV conditions are discussed. (author)

  15. Economic aspect comparison between steel plate reinforced concrete and reinforced concrete technique in reactor containment wall construction

    International Nuclear Information System (INIS)

    Construction costs of nuclear power plant were high due to the construction delays, regulatory delays, redesign requirement, and difficulties in construction management. Based on US DOE (United States Department of Energy) study in 2004, there were thirteen advanced construction technologies which were potential to reduce the construction time of nuclear power plant. Among these technologies was the application of steel-plate reinforced concrete (SC) on reactor containment construction. The conventional reinforced concrete (RC) technique were built in place and require more time to remove framework since the external form is temporary. Meanwhile, the SC technique offered a more efficient way to placing concrete by using a permanent external form made of steel. The objective of this study was to calculate construction duration and economic comparison between RC and SC technique. The result of this study showed that SC technique could reduce the construction time by 60% and 29,7% cost reduced compare to the RC technique. (author)

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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…

  2. 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...

  3. 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...

  4. New concrete materials technology for competitive house building

    OpenAIRE

    Peterson, Markus

    2003-01-01

    The research project aims at investigating the potential of new concrete materials technology (high performance concrete, HPC and self-compacting concete, SCC) for competitive design, production and function of structural frames of cast in-situ concrete in house building.

  5. 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.

  6. 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.

  7. STRUCTURAL VIOLENCE: A STUDY OF CASTE IN GUJARAT

    Directory of Open Access Journals (Sweden)

    Arif Rasheed

    2015-10-01

    Full Text Available Indian democracy is more than six decades old but a large number of its citizens are still yearning for equal treatment. Identity based discrimination is practiced in different visible and invisible forms across the country. Gujarat is certainly one of the most developed States of India but a large number of cases involving structural violence are found in this State as well. The caste identity is a major factor discriminating dalit community from other hindus and they are not permitted to freely enter the house of upper caste, religious places and donot have access to community drinking water. The act of keeping a particular section of the society out of touch is an example of structural violence. The present paper focuses on the instances of discrimination faced by people of lower strata in administrative, social and economic spheres in this techno advance State of India.

  8. 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...

  9. 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

  10. 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

  11. 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)

  12. 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)

  13. 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...

  14. 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...

  15. 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 ...

  16. 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...

  17. Complex Doping of Uranium under Centrifugal Casting in Zirconium Mold

    International Nuclear Information System (INIS)

    The paper presents the results of the investigation on the structure and distribution pattern of the doping elements in uranium casting, produced by the centrifugal casting in a sealed zirconium mold. It is investigated the possibility of complex zirconium and iron doping of uranium. The values of the zirconium mold dissolution rate against the centrifugal casting time are provided. The mechanism is suggested for doping uranium with the elements included in the mold material during the fuel rod fabrication by the centrifugal casting

  18. 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.

  19. 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...

  20. Development Of Pallan Caste In Tamil Nadu - Hindrance And Contributive Factors

    OpenAIRE

    B. Jawaharlal Nehru

    2013-01-01

    Pallan caste is sub – sect of scheduled castes in Tamil Nadu. Pallan caste people possess their own cultural heritage among the scheduled caste. This paper narrates about the hindrance contributive and factors for development of Pallan in Tamil Nadu.

  1. 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...

  2. Assessment of behavior, design and testing of anchors for fastening to concrete

    International Nuclear Information System (INIS)

    This report presents the evaluation of behavior and the prediction of tensile capacity of anchors that fail concrete, as the design basis for anchorage. Tests of cast-in place headed anchors, domestically manufactured and installed in uncracked, unreinforced concrete were performed to investigate the behavior of single anchors and multiple anchors with the consideration of various embedment lengths and edge distances. The failure mode and the load-deformation response of these anchors are discussed and the concrete failure data then compared with capacities by the two exiting methods : the 45 degree cone method of ACI 349, appendix B and the Concrete Capacity Design (CCD) method. Discrepancies between the test results and these two prediction methods are assessed and also the basic differences in philosophy and the factors contributing to the philosophical differences in these two methods are addressed

  3. 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...

  4. 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...

  5. A Study on the Cover Failure in Concrete Structure Following Concrete Deterioration

    International Nuclear Information System (INIS)

    The RC (Reinforced Concrete) structures in the spent fuel dry storage is required structural integrity for a long period of the service life time. A study on the concrete cracking behavior by stress on concrete is necessary for life time estimation of structures because concrete cracking can reduce the radiation shielding performance and deteriorate the durability of spent fuel dry storage. The purpose of this study is to analyze the relationship between the range of the steel expansion and the crack creation and propagation using the ABAQUS tool. Parameters used in this study were concrete strength, concrete cover depth and the steel diameter. The value of steel radius to volume expansion was applied to suppose the expansion of reinforcing bar under the load condition. As a result of this case study, it is confirmed that the critical steel expansion which can initiate cracking is proportional to tensile strength. And primary factors which effect crack creation of concrete cover are in order of concrete strength, cover thickness and steel diameter. If concrete strength is lowered about its 30%, the rate of surface crack occurrence accelerates 15 times maximally. The critical expansion value of steel increased as the increment of concrete cover depth. The surface cracking of concrete cover was created at the value of steel expansion, ranging from 0.019 to 0.051 mm under the cover depth 50 mm. (authors)

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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...

  11. 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

  12. 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

  13. 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.

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

    OpenAIRE

    BİNİCİ, Hanifi; İsmail H. ÇAĞATAY; Kaplan, Hasan

    2000-01-01

    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.

  15. 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...

  16. 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...

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

    Directory of Open Access Journals (Sweden)

    Cai Qizhou

    2008-05-01

    Full Text Available 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 ductile iron (ADI are briefl y depicted. The new development of ductile 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.

  18. 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.

  19. StatsCasts: screencasts for complementing lectures in statistics classes

    Science.gov (United States)

    Dunn, Peter K.; McDonald, Christine; Loch, Birgit

    2015-05-01

    Students who are studying introductory statistics units but are enrolled in non-statistics majors often struggle with the content, and do not stay engaged. Support structures are in place at many Australian universities to help these students. Most of these are face-to-face support centres that the students can visit during opening hours. To provide additional assistance to these students any time, and from anywhere, online media are increasingly used by students - either provided by support centres, or sought independently by students. Little research has been undertaken on the effectiveness of such resources to support student learning. This paper investigates whether students will embrace StatsCasts - short screen-capture videos on key statistical topics that students have struggled with in the past, with narrator explanation provided by the lecturer - as part of their learning strategy and if they will actively engage with the videos. Students enrolled in a large first-year statistics class at an Australian university who had been provided with StatsCasts responded to a survey at the end of the semester. Volunteering students also participated in a focus group to probe deeper into students' perceptions of and motivations for watching the videos. Analysis of the data shows that students do actively engage with the StatsCasts and they appear to become an important component of their study and revision strategy.

  20. Damage detection in concrete and cementitious composites

    Science.gov (United States)

    Wu, Hwai-Chung; Pai, P. Frank

    2008-03-01

    Traditionally ultrasonic testing is used to estimate the extent of damage in a concrete structure. However Pulse-velocity and amplitude attenuation methods are not very reliable, and are difficult to reveal early damage of concrete. In a previous study, a new active modulation approach, Nonlinear Active Wave Modulation Spectroscopy, was developed and found promising for early detection of damage in concrete. In this procedure, a probe wave is passed through the system in a fashion similar to regular acoustic methods for inspection. Simultaneously, a second, low-frequency modulating wave is applied to the system to effectively change the size and stiffness of flaws microscopically and cyclically, thereby causing the frequency modulation to change cyclically as well. It has been also shown that it is advantageous to apply the Hilbert-Huang transform to decompose nonlinear non-stationary time-domain responses of plain concrete. Such procedure leads to improving the damage detection sensitivity of this modulation method in concrete. In this paper, further investigation on mortar and fiber reinforced concrete will be presented and discussed.

  1. Statistical analysis of ultrasonic measurements in concrete

    Science.gov (United States)

    Chiang, Chih-Hung; Chen, Po-Chih

    2002-05-01

    Stress wave techniques such as measurements of ultrasonic pulse velocity are often used to evaluate concrete quality in structures. For proper interpretation of measurement results, the dependence of pulse transit time on the average acoustic impedance and the material homogeneity along the sound path need to be examined. Semi-direct measurement of pulse velocity could be more convenient than through transmission measurement. It is not necessary to assess both sides of concrete floors or walls. A novel measurement scheme is proposed and verified based on statistical analysis. It is shown that Semi-direct measurements are very effective for gathering large amount of pulse velocity data from concrete reference specimens. The variability of measurements is comparable with that reported by American Concrete Institute using either break-off or pullout tests.

  2. The lost foam process in pilot castings plattes

    Directory of Open Access Journals (Sweden)

    Z. Żółkiewicz

    2009-04-01

    Full Text Available The paper discusses the process of thermal evaporation of a foundry pattern. At several research-development centres, studies have beencarried out to examine the physico-chemical phenomena that take place in foundry mould filled with polystyrene pattern when it is pouredwith molten metal. In the technique of evaporative patterns, the process of mould filling with molten metal (the said mould holding inside a polystyrene pattern is interrelated with the process of thermal decomposition of this pattern. The process of polystyrene pattern evaporation in foundry mould under the effect of molten metal is of a very complex nature and depends on many different factors, still not fully investigated. The technology of evaporative patterns was used in manufacture of pilot castings of the high abrasion resistance plates. The material and the properties of the resultant castings were determined by the customer (patent protection. At the beginning of the studies, the properties of the pattern material were determined, patterns were assembled, the properties of the ceramic layer were determined as well as the technique of its preparation and application. The technique of molten metal feeding to the mould cavity was examined along with the parameters of the gating and feeding system, and casting cooling and solidification conditions (large contraction, shrinkage cavities and depressions.

  3. 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

  4. Measurement of neutron activation in concrete samples

    International Nuclear Information System (INIS)

    The results of activation studies of ordinary and barytes concrete samples relevant for research reactor decommissioning are given. Five important long-lived radioactive isotopes (54Mn, 60Co, 65Zn, 133Ba, and 152Eu) were identified from the gamma-ray spectra measured in the irradiated concrete samples. Activation of these samples was also calculated using ORIGEN2 code. Comparison of calculated and measured results is given. (author)

  5. Humidity measurements in the precast concrete

    International Nuclear Information System (INIS)

    The precast concrete industry manufactures requires a good knowledge and control of the humidity factor: during the manufacturing process, in order to regulate the water content of aggregates, or the fresh concrete workability: during the quality control of the product characteristics. The principles of measurements: conductivity, dielectric characteristics and neutron moisture meters are compared for cost, humidity range, accuracy, temperature dependence, interfering elements, density dependence, grain size and shape

  6. 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

  7. 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.

  8. The prediction of bubble defects in castings

    OpenAIRE

    Lawrence, James Andrew

    2004-01-01

    Objective of this research was to develop models that capture the entrainment, breakup and transport of gas bubbles in solidifying TiAl castings. The candidate has reviewed the literature, programmed in FORTRAN code, and validated a number of competing techniques for two phase flow relevant to the filling of moulds. He has developed a hybrid (Donor-acceptor/ Level Set) method, which captures the characteristics of gas bubbles based on the surface tension —fluid inertia balance on the free sur...

  9. 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...

  10. Phase Transformation in Cast Superaustenitic Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Nathaniel Steven Lee Phillips

    2006-12-12

    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.

  11. 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.

  12. Level measurement in electromagnetic continuous casting

    International Nuclear Information System (INIS)

    Level measurement method of molten metal have been investigated to apply in the electromagnetic continuous casting. The level measuring principle was based on the electromagnetic induction and search coil type of magnetic sensor was chosen as a level sensor, Before construct the level meter, the artificial cold charges was used to characterize the sensor output according to the level, the coil current, and the aging. Considering the results of basic experiments, we constructed a level measurement system and applied it to electromagnetic continuous casting at a billet caster of POSCO works. The developed level meter showed that the resolution of the level was within ±0.3 mm, the dynamic range of sensing was from the top of the mold to 300 mm below the top of the mold. It worked well with the existing control device in supplying the molten steel to the mold.

  13. 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.

  14. Special concretes for protection in piles (1963)

    International Nuclear Information System (INIS)

    The report reviews the main concretes used for the protection of reactors. First are examined the general factors affecting the selection of concretes for protection; some of the general aspects of radiation attenuation (fast and thermal neutrons, γ) are then recalled. After an enumeration of the qualities and defects of conventional concretes, desirable or possible improvements are proposed: introduction of heavy elements for increasing the efficiency with respect to fast neutrons and γ; increase in the hydrogen content (as H2O), addition of absorbent products (B, Li, rare earths) for thermal neutron capture. A list is given of the principal products used for this purpose. Finally there is a rapid review of the preparation, the stability with time, and the resistance to radiation and to heat. Appendices and tables give details and numerical values. Appendix 1 deals with the question of water in concretes. Appendix 2 gives a classification of concretes based mainly on their density. At the end, ten tables give the compositions and values of the physical and mechanical characteristics of sixteen particularly typical concretes. (authors)

  15. 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.

  16. 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

  17. 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...

  18. 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...

  19. 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,…

  20. 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...

  1. Analysis of production factors in high performance concrete

    OpenAIRE

    Gilberto Carbonari; Ravindra Gettu; Luiz Agullo; Berenice Martins Toralles Carbonari

    2003-01-01

    The incorporation of silica fume and superplasticizers in high strength and high performance concrete, along with a low water-cement ratio, leads to significant changes in the workability and the energy needed to homogenize and compact the concrete. Moreover, several aspects of concrete production that are not critical for conventional concrete are important for high strength concrete. This paper will discuss the need for controlling the humidity of the aggregates, optimizing the mixing seque...

  2. Possibilities of Using Concrete Waste in the Further Production of Concrete Composite

    OpenAIRE

    Olga Finoženok; Ramunė Žurauskienė

    2011-01-01

    Concrete is a secure building material due to outstanding characteristics of which used in different constructions all over the world. A number of scientists examined the use of different waste products in building material manufacture in order to economize the input of energy and natural resources. On the basis of conducted tests, we can maintain that after 28 days of consolidation, the strength of concrete in the process of manufacturing of which the coarse aggregate of concrete waste was u...

  3. 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

  4. Transfer and anchorage bond behaviour in self-compacting concrete

    OpenAIRE

    Rigueira-Víctor, J. W.; Arbeláez, C. A.; Serna-Ros, P.; Martí-Vargas, J. R.

    2006-01-01

    Self-compacting concretes (SCC) provide solutions to the problems facing precast concrete construction, enhancing competitiveness, reducing turnaround times and improving final product quality. SCC is fast becoming a key product for the future development of the precast pre-stressed concrete industry.The present paper compares the bond performance of SCC and traditional concrete (TC). The bond performance results confirm the viability of SCC in precast pre-stressed concrete manufacture, despi...

  5. Potential reduction of concrete deterioration through controlled DEF in hydrated concrete

    OpenAIRE

    Lubej, Samo; Radosavljevic, Milan

    2015-01-01

    Delayed ettringite formation (DEF) is a chemical reaction with proven damaging effects on hydrated concrete. Ettringite crystals can cause cracks and their widening due to pressure on cracked walls caused by the positive volume difference in the reaction. Concrete may show improvements in strength at early ages but further growth of cracks causes widening and spreading through the concrete structure. In this study, finely dispersed crystallization nuclei achieved by adding air-entraining agen...

  6. EFFECTS OF CHEMICAL ADMIXTURES ON SPECIALITIES OF HARDENED CONCRETE USED IN READY CONCRETE PRODUCTION IN ESKİŞEHİR

    OpenAIRE

    TOPÇU, İlker Bekir; IŞIKDAĞ, Burak; Özgür TATAR

    2006-01-01

    In this study polls were taken from different ready mixed concrete firms in Eskişehir. Chemical admixtures used in concrete production were investigated according to the polls, and some information about chemical admixtures was obtained. Compressive strengths of concrete specimens manufactured by ready mixed concrete firms were evaluated, and results were investigated due to different types and proportions of admixtures used in concrete. Chemical admixtures were compared to each other at the ...

  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. Casting of 3-dimensional footwear prints in snow with foam blocks.

    Science.gov (United States)

    Petraco, Nicholas; Sherman, Hal; Dumitra, Aurora; Roberts, Marcel

    2016-06-01

    Commercially available foam blocks are presented as an alternative material for the casting and preservation of 3-dimensional footwear impressions located in snow. The method generates highly detailed foam casts of questioned footwear impressions. These casts can be compared to the known outsole standards made from the suspects' footwear. Modification of the commercially available foam casting blocks is simple and fast. The foam block is removed and a piece of cardboard is secured to one side of the block with painter's masking tape. The prepared foam block is then placed back into its original box, marked appropriately, closed and stored until needed. When required the foam block is carefully removed from its storage box and gently placed, foam side down, over the questioned footwear impression. Next, the crime scene technician's hands are placed on top of the cardboard and pressure is gently applied by firmly pressing down onto the impression. The foam cast is removed, dried and placed back into its original container and sealed. The resulting 3D impressions can be directly compared to the outsole of known suspected item(s) of footwear. PMID:27124876

  10. 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

  11. 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.

  12. 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.

  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. 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.

  15. 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.

  16. 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....

  17. The Belgian super-container concept: Study of the concrete buffer behaviour in service life

    International Nuclear Information System (INIS)

    The ONDRAF/NIRAS agency for radioactive waste and enriched fissile materials is in charge of the management of the radioactive wastes in Belgium. In the framework of the study of a new concept for the disposal of high level wastes, a project of a super-container has been considered and studied. The main goal of this study was to estimate the Thermo-Hydrological behaviour of the concrete buffer in service life. Water (liquid and vapour) and heat transfers were described through coupled differential equations by the means of the procedure THYDR developed at the Department of Physico-Chemistry of the French Commission for Atomic Energy (CEA/DPC) and implemented in the code CAST3M. Two different configurations for the concrete buffer were investigated: concrete cured with no water loss or partially dried. The simulations allowed the estimation of the evolution of both vapour pressure and liquid saturation. (author)

  18. Moisture Transport in Concrete Structures in Swedish Hydro Power Plants

    OpenAIRE

    Rosenqvist, Martin

    2011-01-01

    Concrete structures in hydro power plants exposed to harsh environment, such as non-frozen freshwater and long cold winters with freezing temperatures, are always in the danger-zone for suffering from concrete damages. Some existing concrete structures already suffer from different damages caused by high water content. The conditions regarding concrete quality, air entrainment, temperature and time will be investigated experimentally and theoretically in this doctoral study. The results could...

  19. The dry storage of used fuel in concrete canisters in Canada

    International Nuclear Information System (INIS)

    The Whiteshell Nuclear Research Establishment (WNRE) initiated a program for dry storage of used CANDU fuel in concrete canisters in 1975. Over the past decade, 17 Mg of fuel have been placed in concrete canister storage at WNRE. In 1985, the WNRE concrete canister design was used for the first time commercially for the interim, on-site storage of 67 Mg of fuel from the Gentilly-1 power reactor at the Gentilly site in the Province of Quebec. This report describes various aspects of this interim storage method. The discussion includes the concept, applications, overall operating experience, licensing aspects, and quality assurance standards and their development

  20. 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.

  1. 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.

  2. Caste differences in Pseudopolybia compressa (Hymenoptera: Vespidae: Polistinae)

    OpenAIRE

    Laura Chavarría Pizarro; Noll, Fernando B; Sidnei Mateus

    2009-01-01

    Studies of morphological caste syndromes in the tribe Epiponini help us to understand the evolution of social behavior in insects. Few studies have integrated morphological syndromes of various species from the same or distinct genera. We studied morphological differences between castes from three colonies of Pseudopolybia compressa de Saussure, 1854, in order to relate their caste syndrome with those of other species in the genus. We took eight morphometric measures and females were classifi...

  3. 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.

  4. 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.

  5. 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.

  6. 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...... exhibit favorable opinion about reservation in jobs for the lower caste....

  7. Automatic inspection of surface defects in die castings after machining

    OpenAIRE

    S. J. Świłło; M. Perzyk

    2011-01-01

    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 pri...

  8. 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

  9. 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

  10. 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.

  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. 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

  14. 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...

  15. 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)

  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. 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.

  18. A study on the mix design and fundamental properties of pre-cast concrete artifacts prepared with coarse and fine recycled aggregates

    OpenAIRE

    Garcia Navarro, Justo; Guzmán Báez, Ana de; Cervantes Villamuelas, Miguel

    2010-01-01

    This paper analyzes the use of Construction and Demolition Waste as aggregate in precast concrete artifacts production incorporating coarse and fine fractions. The recycled aggregates used were sourced from a Spanish sorting facility and were mainly composed of concrete rubbles and ceramic materials. A complete study of the properties of the aggregates was carried out and laboratory trials were conducted to investigate the possibility of the use of 10%, 20%, 30% and 50% contents of coa...

  19. 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.

  20. 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...

  1. Specificities of foundations for turbosets and of concrete structures in seismic localities - experience from abroad

    International Nuclear Information System (INIS)

    The method is described of elastically laid foundations of turbosets mainly suitable for seismic localities. Support structures are first built under the foundation. Then the boarding is prepared for the upper foundation plate and prestress--ed insulators are placed in the appertures in the bottom in such a manner that by their lower collar they bear on the prepared places in the support structure. On the placed insulators a set of spacing sheets is then placed. Reinforcement and concreting are performed using routine methods. Various admixtures are added to the concrete which improve the processibility of the mix and extend setting time to prevent excessive shrinkage of concrete due to an increase in hydration heat. (J.H.)

  2. Detecting the Presence of High Water-to-Cement Ratio in Concrete Surfaces Using Highly Nonlinear Solitary Waves

    OpenAIRE

    Piervincenzo Rizzo; Amir Nasrollahi; Wen Deng; Julie M. Vandenbossche

    2016-01-01

    We describe a nondestructive evaluation (NDE) method based on the propagation of highly nonlinear solitary waves (HNSWs) to determine the excess of water on the surface of existing concrete structures. HNSWs are induced in a one-dimensional granular chain placed in contact with the concrete to be tested. The chain is part of a built-in transducer designed and assembled to exploit the dynamic interaction between the particles and the concrete. The hypothesis is that the interaction depends on ...

  3. The use of acoustic monitoring to manage concrete structures in the nuclear industry

    International Nuclear Information System (INIS)

    Concrete and steel are widely used in containment vessels within the nuclear industry. Both are excellent acoustic transmitters. In many structures tensioned wire elements are used within containment structures. However, tensioned wire can be vulnerable to corrosion. To reduce the probability of corrosion sophisticated protection systems are used. To confirm that the design strength is available through time, extensive inspection and maintenance regimes are implemented. These regimes include tests to confirm the condition of the post-tensioning, and pressure tests (leak tests) to verify the performance of vessel. This paper presents an acoustic monitoring technology which uses widely distributed sensors to detect and locate wire failures using the energy released at failure. The technology has been used on a range of structures including post-tensioned concrete bridges, suspension bridges, buildings, pre-cast concrete cylinder pipelines (PCCP) and prestressed concrete containment vessels (PCCV), where it has increased confidence in structures and reduced maintenance costs. Where the level of ambient noise is low then SoundPrint acoustic monitoring can detect concrete cracking. This has been shown in PCCP pipelines, on laboratory test structures and also in nuclear structures. The programme has shown that distributed sensors can locate internal cracking well before there is any external evidence. Several projects have been completed on nuclear vessels. The first has been completed on an Electricite de France (EDF) concrete test pressure vessel at Civaux in France. The second at the Sandia PCCV Test Vessel in Albuquerque, New Mexico, USA, which involved the testing of a steel lined concrete vessel. The third was on a PCCV in Maryland, USA. Acoustic monitoring is also able to monitor the deterioration of post-tensioned concrete structures as a result of seismic activity. Summary details of a case history are presented. (authors)

  4. The use of acoustic monitoring to manage concrete structures in the nuclear industry

    International Nuclear Information System (INIS)

    Concrete and steel are widely used in containment vessels within the nuclear industry. Both are excellent acoustic transmitters. In many structures tensioned wire elements are used within containment structures. However, tensioned wire can be vulnerable to corrosion. To reduce the probability of corrosion sophisticated protection systems are used. To confirm that the design strength is available through time, extensive inspection and maintenance regimes are implemented. These regimes include tests to confirm the condition of the post-tensioning, and pressure tests (leak tests) to verify the performance of vessel. This paper presents an acoustic monitoring technology which uses widely distributed sensors to detect and locate wire failures using the energy released at failure. The technology has been used on a range of structures including post-tensioned concrete bridges, suspension bridges, buildings, pre-cast concrete cylinder pipelines (PCCP) and prestressed concrete containment vessels (PCCV), where it has increased confidence in structures and reduced maintenance costs. Where the level of ambient noise is low then SoundPrint acoustic monitoring can detect concrete cracking. This has been shown in PCCP pipelines, on laboratory test structures and also in nuclear structures. The programme has shown that distributed sensors can locate internal cracking well before there is any external evidence. Several projects have been completed on nuclear vessels. The first has been completed on an Electricite de France (EDF) concrete test pressure vessel at Civaux in France. The second at the Sandia PCCV Test Vessel in Albuquerque, New Mexico, USA, which involved the testing of a steel lined concrete vessel. The third was on a PCCV in Maryland, USA. Acoustic monitoring is also able to monitor the deterioration of post-tensioned concrete structures as a result of seismic activity. Summary details of a case history are presented. (author)

  5. 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.

  6. 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)

  7. Synergy, inteligibility and revelation in neighbourhood places

    OpenAIRE

    Dalton, N. S. C.

    2011-01-01

    In architectural and urban design the notion of place is highly desired, or in its absence, strongly criticised. Yet what is place and how might it be engendered by design? Over the last 30 years an extensive body of research on place has emerged, largely based on phenomenological approaches. This work gives rise to the question of whether place is a purely social concept completely divorced from physical space, or is linked to space and therefore amenable to design based inter...

  8. 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…

  9. 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

  10. 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.

  11. 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...

  12. Self-flowing underwater concrete mixtures for high rise structures

    International Nuclear Information System (INIS)

    Placement of conventional concrete mixtures in underwater construction results in a high percentage of material loss due to washout of cement paste. This paper presents the influence of anti washout admixture (AWA) on various properties of concrete. Eleven self-flowing concrete (SFC) mixtures using type II cement were proportioned. A combination of low water cement (w/c), high cement contents, anti washout admixtures, fly ash, and silica fume were used to enhance the resistance of fresh concrete to washout. The concrete mixtures proportioned to be highly flow able, self-leveling and cohesive. The water-cementitious materials ratios ranged between 0.356 and 0.392 which correspond a typical underwater concrete mixture. The concrete mixtures were tested for slump, slump flow, washout resistance and compressive strength. The compressive strength of each concrete mixture cast underwater was determined at 3, 7, 28 days and compared with the compressive strength of the same concrete mixture cast in normal condition (in air). Test results indicated that the use of an AWA facilitates the production of flow able concrete mixtures with the added benefit of lower washout loss. Concrete mixture proportioned using Type II cement and fly ash at level of replacement of 15% was found to develop self flowing concrete with better fresh and hardened properties and more resistant to washout. The self-flowing underwater concretes developed a 28-day compressive strengths ranging from 20 to 28 MPa

  13. Radiation Exposure to Concrete in Israel

    International Nuclear Information System (INIS)

    Most building materials of terrestrial origin contain small amounts of radionuclides of natural origin, mainly from the Uranium (238U) and Thorium (232Th) decay chains and the radioactive isotope of potassium, 40K. The external radiation exposure is caused by gamma emitting radionuclides, which in the uranium series mainly belong to the decay chain segment starting with Radium (226Ra). The internal (by inhalation) radiation exposure is due to Radon (222Rn), and its short lived decay products, exhaled from building materials into the room air. Due to economical and environmental reasons there is an increased tendency to use industrial by-products containing relatively high concentrations of radionuclides of natural origin in the building material industry. Fly ash (FA), produced as by-product in the combustion of coal, is extensively used in Israel since mid eighties of the last century in concrete and as an additive to cement . The increase of 226Ra activity concentration, the mineralogical characteristics of the FA and of the concrete may influence on the radon exhalation rate and consequently on the radon exposure of the public. The recently published Israeli Standard 5098 (IS 5098) 'Content of natural radioactive elements in building products' limits the content of natural radionuclides as well as the radon emanation from concrete. This paper presents a compilation of three studies conducted at Soreq Nuclear Research Centre (SNRC), Technion, NRG and Environmental Lab BGU (ELBGU) to investigate and quantify the influence of FA addition in concrete

  14. Evaluation of corrosion effect in reinforced concrete by chloride exposure

    Science.gov (United States)

    Loreto, G.; Di Benedetti, M.; Iovino, R.; Nanni, A.; Gonzalez, M. A.

    2011-04-01

    Durability is generally described as the ability of a material to maintain its physical and mechanical properties over time. In reinforced concrete (RC) structures, concrete is the ideal material to protect the steel reinforcement given its high alkalinity. In environments subjected to highly aggressive conditions, mostly due to the presence of chlorides, concrete may lose its protective characteristics and allow for accelerated ageing. Concrete degradation and steel reinforcement corrosion are phenomena closely connected. The aim of this research work is the characterization of the relationship between steel reinforcement corrosion and concrete degradation under accelerated ageing in a 3% sodium chloride solution. The method of linear polarization is used for identification of the corrosion rate of the steel bar. Additionally, the values of concrete residual strength are obtained, and correlated to both the corrosion rate and width of concrete cracks. Finally, the prediction of the concrete cover useful life is estimated.

  15. Concrete with Nano-Additives in Thin Wall Shell Structures

    OpenAIRE

    Lūsis, V; Krasņikovs, A; I. Boiko; Geriņa-Ancāne, A

    2013-01-01

    In the present paper physical and mechanical properties of glass fibre fibrous concrete as well as its technological possibilities in the production of definite shells have been studied. Production technology patented by RTU Concrete Mechanics Laboratory was used. This technology allows developing and obtaining different shells from fibrous concrete, including also dome structures and two-plane bended shells with smooth inner and outer surfaces. Concrete is spread in the necessary thickness o...

  16. 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...

  17. 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

  18. GPR measurements of attenuation in concrete

    International Nuclear Information System (INIS)

    Ground-penetrating radar (GPR) signals from concrete structures are affected by several phenomenon, including: (1) transmission and reflection coefficients at interfaces; (2) the radiation patterns of the antenna(s) being used; and (3) the material properties of concrete and any embedded objects. In this paper we investigate different schemes for determining the electromagnetic (EM) attenuation of concrete from measured signals obtained using commercially-available GPR equipment. We adapt procedures commonly used in ultrasonic inspections where one compares the relative strengths of two or more signals having different travel paths through the material of interest. After correcting for beam spread (i.e., diffraction), interface phenomena, and equipment amplification settings, any remaining signal differences are assumed to be due to attenuation thus allowing the attenuation coefficient (say, in dB of loss per inch of travel) to be estimated. We begin with a brief overview of our approach, and then discuss how diffraction corrections were determined for our two 1.6 GHz GPR antennas. We then present results of attenuation measurements for two types of concrete using both pulse/echo and pitch/catch measurement setups

  19. 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...

  20. Radon exhalation from and diffusion in concrete

    International Nuclear Information System (INIS)

    Cylindrical test pieces of concrete are used for measurements of 222Rn exhalation rates. Except one flat end surface of a test piece, other parts of its exteriority are covered with sealant. Radon atoms can escape only through its end surface from the interior into the outside air. This treatment makes the radon transport in the concrete one dimensional phenomena. The piece is put in an airtight container. Time variations of radon concentrations in the air of the container are measured with a plane multiwire-electrode ionization chamber. From this result, the radon areal exhalation rate is deduced for the piece. Exhalation rates are measured for four pieces with different length. Then, the diffusion coefficient is obtained for radon in the concrete as (5.0 ± 1.0) x 10-8m2s-1 (a one-block method). A two-block method has been invented to obtain simultaneously values of three parameters: diffusion coefficient, porosity of concrete, and radon production rate in the pore air in the concrete. Except one end surface, the exterior is sealed preventing radon atoms from leaking out into the air. Areal exhalation rates are measured for six two-block objects linked together with pipes of different length. From these results, values of three parameters are deduced as (3.9 ± 0.5) x 10-8m2s-1, (6.9 ± 0.2) x 10-2, and (1.21 ± 0.09) x 105 atoms m-3s-1 for diffusion coefficient, porosity, and radon production rate, respectively. This value for diffusion coefficient agrees with that obtained by the one-block method within the experimental errors. The two-block method is shown to be useful to obtain the values of three parameters. Radium contents are obtained by the gamma-ray spectrometry for the concrete, and the materials used for it. The radon diffusion coefficient is measured also for the andesite used as a material of the concrete as (5.9 ± 0.3) x 10-10m2s-1. (author)

  1. 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.

  2. 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

    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......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...

  3. 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.

  4. Caste differences in Pseudopolybia compressa (Hymenoptera: Vespidae: Polistinae

    Directory of Open Access Journals (Sweden)

    Laura Chavarría Pizarro

    2009-12-01

    Full Text Available Studies of morphological caste syndromes in the tribe Epiponini help us to understand the evolution of social behavior in insects. Few studies have integrated morphological syndromes of various species from the same or distinct genera. We studied morphological differences between castes from three colonies of Pseudopolybia compressa de Saussure, 1854, in order to relate their caste syndrome with those of other species in the genus. We took eight morphometric measures and females were classified in relation to ovarian development and spermathecal contents. Females of Colony 1 (C1 present a higher distinction between castes than females of Colonies 2 and 3 (C2 and C3, and, in general, queens of the three colonies are larger than workers in some measures but smaller in others. In Pseudopolybia Dalla Torre, 1894, shape rather than size is a more important trait in caste divergence.

  5. 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.

  6. 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...

  7. 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.

  8. Utilization of Recycled Wastes as Ingredients in Concrete Mix

    OpenAIRE

    Er. Nitish Puri,; Er. Brijesh Kumar; Er. Himanshu Tyagi,

    2013-01-01

    Laboratory experimentation was carried out to analyze the performance of M25 concrete made by partially replacing aggregates with waste materials like construction debris, PVC scrap and leather waste. The resultant concrete was tested for parameters like weight, compressive strength, slump and workability and compared with conventional plain cement concrete. It has been observed that the use of waste materials results in the formation of light weight concrete. There is a considerable increase...

  9. 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...

  10. Fracture and aggregate interlock mechanisms in reinforced concrete

    International Nuclear Information System (INIS)

    Nine tests regarding thin-webbed I-beams failing in shear because of stirrup yielding and concrete crushing are considered here. An incremental-iterative procedure for the nonlinear F.E. analysis of reinforced concrete structures is applied to three of the above beams. Solid concrete is modeled as a hypoelastic material, while cracked concrete (including fracture and aggregate interlock) is modeled with crack bands, according to the smeared crack approach

  11. Cracks in base-restrained plain and reinforced concrete walls

    OpenAIRE

    OUZAA, Kheira; BENMANSOUR, Mohammed Benali

    2010-01-01

    This study deals with the problem of shrinkage cracks in reinforced concrete walls restrained at the base. A finite element model to study cracking of the wall was proposed. Nonlinear behavior of concrete was considered by means of a smeared crack approach. The equations proposed by ACI Committee 209 were used to model the mechanical properties of concrete, as well as the average concrete shrinkage within the thickness of the wall. It was found that the suggested model closely pred...

  12. Saw Dust Ash as Partial Replacement for Cement in Concrete

    OpenAIRE

    Raheem, A. A.; Olasunkanmi, B. S.; Folorunso, C. S.

    2012-01-01

    This research considered the use of saw dust ash as a pozzolan in the production of concrete. the study investigated the physical properties and chemical composition of saw dust ash (SDA) as well as the workability, and compressive strength properties of the concrete produced by replacing 5%, 10%, 15%, 20% and 25% by weight of ordinary Portland cement with SDA. Slump and compacting factor tests were carried out on the fresh concrete and compressive strength test on hardened concrete. The conc...

  13. High temperature corrosion of cast irons and cast steels in dry air

    Energy Technology Data Exchange (ETDEWEB)

    Tholence, F.; Norell, M. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Engineering Metals

    2001-07-01

    The oxidation in dry air of four cast alloys intended for exhaust gas systems has been examined. Particular interest was directed to how the oxide growth was related to the microstructures. The examined alloys were two cast ductile irons, a SiMo alloy (Fe3,86Si0,6Mo3C) and a Ni-Resist alloy (Fe32Ni5,3Si2,1C), and two cast stainless steels, one ferritic (Fe18Cr2,1Mn0,32C) and one austenitic (Fe20Cr9Ni0,47C). Coupons were oxidised for 50 h at temperatures between 650 C and 1050 C. The samples were characterised by using XRD, SEM/EDX and AES. As expected, the overall oxide thickness increased with temperature and partial spallation occurred at the highest temperatures for all alloys. Porous Fe oxide nodules nucleate at the graphite nodules on the ductile irons. These Fe-oxide nodules formed above a continuous layer of Fe-Si-oxide for the SiMo and mixed Fe-Ni-Si oxides for the Ni-Resist. The total oxide thickness is about (60 {mu}m). Thick oxides at the interdendritic regions in the cast steels were attributed to non-Cr-carbides. Segregation of Cr directed the formation of iron oxide nodules to the centre of the dendrites in the austenitic alloy. (orig.)

  14. 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.

  15. 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.

  16. Acoustic energy transmission in cast iron pipelines

    Science.gov (United States)

    Kiziroglou, Michail E.; Boyle, David E.; Wright, Steven W.; Yeatman, Eric M.

    2015-12-01

    In this paper we propose acoustic power transfer as a method for the remote powering of pipeline sensor nodes. A theoretical framework of acoustic power propagation in the ceramic transducers and the metal structures is drawn, based on the Mason equivalent circuit. The effect of mounting on the electrical response of piezoelectric transducers is studied experimentally. Using two identical transducer structures, power transmission of 0.33 mW through a 1 m long, 118 mm diameter cast iron pipe, with 8 mm wall thickness is demonstrated, at 1 V received voltage amplitude. A near-linear relationship between input and output voltage is observed. These results show that it is possible to deliver significant power to sensor nodes through acoustic waves in solid structures. The proposed method may enable the implementation of acoustic - powered wireless sensor nodes for structural and operation monitoring of pipeline infrastructure.

  17. 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.

  18. 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.

  19. Behavior of cermets (Fe powder + Al2O3) obtained 'in situ' in cast iron

    International Nuclear Information System (INIS)

    The introduction of hard ceramic particles in a ferrous matrix modifies its behavior when undergoing stresses associated with wear resistance. So that this occurs, the particles must be properly selected, with reference to their hardness, size, shape and dispersion. These compound materials are called MMC (metal matrix composites) or cermets. This work looks at the methodology for producing cast iron pieces using a traditional sand mold casting process, using MMC tablets, and placing them in some areas of the piece that will undergo wear from abrasion. The following steps are described in the production of MMC tablets and of the casting material in the foundry's pilot plant. The material was studied and the metallurgical quality was evaluated together with its resistance to the abrasive wear

  20. 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.

  1. 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.

  2. 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.

  3. 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, ...

  4. 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…

  5. 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

  6. 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.

  7. 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.)

  8. 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…

  9. 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

  10. 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...

  11. 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

  12. 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...

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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)

  20. 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)

  1. 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: a...... beam with a typical reinforcement ratio, and a beam with a small reinforcement ratio. The modal properties of the beams were found exciting the beams by a series of pulses and identifying the properties using ARMA and ARMAX models. It was found, that extremely small damages could be detected, that the...... significance of detection was only slightly improved using the measured input signal, and finally that it was easier to detect damage in a normally reinforced beam than in a lightly reinforced beam....

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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...

  8. Modelling Tension Stiffening in Reinforced Concrete Structures

    DEFF Research Database (Denmark)

    Christiansen, Morten Bo; Nielsen, Mogens Peter

    1997-01-01

    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...... crack widths predicted by the models are compared with experimental data from tests on tension rods as well as flexural beams.In the light of the simple assumptions made and the random nature of cracking, the accordance between the models and the test data is quite good.Part II of the present thesis...... the light of the simple assumptions, quite good accordance is found.Part III of the thesis deals with the deformations of a beam symmetrically loaded by two concentrated forces. In the shear-flexure beam model it is assumed that the load is carried by means of a stringer system and a diagonal stress...

  9. Section 2--Psychology in Its Place

    Science.gov (United States)

    Radford, John

    2008-01-01

    In 1996, Graham Richards published "Putting Psychology in its Place: An introduction from a critical historical perspective." Here, I seek to consider what is or should be the "place" of Psychology in education, more particularly Higher Education, and not just from a historical perspective. This raises issues about several contexts in which…

  10. 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

  11. Analysis of reactive stress in concrete reinforcement of reinforced concrete blocks joined with pressed joints

    International Nuclear Information System (INIS)

    The possible replacement was considered of welded joints on concrete reinforcements in rigid structures by pressed sleeve joints. The effects on inner stress of joint reinforced concrete blocks were compared. A laboratory test was performed aimed at establishing the size and the course of stress induced in the models of reinforced concrete block structures by the sleeve joints of the individual reinforcements. Static calculations were carried out of stress and deformation of the spatial rod structure consisting of two extreme models of reinforced concrete blocks, loaded with longitudinal rod deformation in pressed sleeve joint points. The magnetoelastic method was used in testing stress in the reinforcement. Models are described for the laboratory tests and the measured and the calculated values are listed of reactive stress in the rods. The measurements and the calculations showed that the method of anchoring the reinforcement in the reinforced concrete structure significantly affects the magnitude of stress. It was shown that the welded joint with an experimentally observed free shrinkage of about 0.8 mm exerted a similar effect on the stress of the reinforcement like the pressed joint. Pressed joint sleeves can be used in the design of reinforced concrete blocks for the Mochovce nuclear power plant. (J.B.). 9 figs., 3 tabs., 4 refs

  12. 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)

  13. 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...

  14. Safety Assessment in Installation of Precast Concrete

    OpenAIRE

    Yashrri S.N.; Hanizam A.

    2014-01-01

    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 Kontra...

  15. Formation of microstructures in the spheroidal graphite cast iron

    International Nuclear Information System (INIS)

    Pipeline systems for hydraulic networks are obtained via centrifugal casting of spheroidal graphite cast iron. The very high cooling rate that is achieved in the skin of the product can sometimes lead to carbide instead of graphite in cast iron. An experimental device has been built in the laboratory that allows reproducing the extreme thermal conditions encountered during formation of skin of centrifugally cast pipes. Liquid metal droplets fall on a cold substrate. Rapid directional solidification occurs. The temperature evolution of the lower surface of the droplet is recorded during the very first moment of the solidification (t < 200 ms) thanks to a photodiode, which is located below the substrate. The microstructures that are obtained in laboratory are characterised in both the as-cast state and the heat-treated state. They are compared to the centrifugally cast ones. A model of directional solidification of cast iron under a very large temperature gradient has been built. It allows explaining the transition from stable to metastable micro structure that was observed in the products and reproduced in the laboratory samples.

  16. 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; Svensson, Ingvar L; Seifeddine, Salem

    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...

  17. A Place for Everything and Literature in Its Place.

    Science.gov (United States)

    Roser, Nancy L.

    2001-01-01

    Considers how to teach children to become proficient readers and writers in combination with teaching them to appreciate the "art form" of language. Argues that it is unrealistic to expect teachers with pressing responsibilities to regard children's literature as sacred texts--art forms that are too fragile to be transgressed upon by instructional…

  18. 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.

  19. The ‘full sleeve’ application in the horizontal cold-chamber machine for pressure die casting of aluminium alloys

    OpenAIRE

    Konopka, Z.; A. Zyska; M. Łągiewka; Bielecka, A.; S. Nocuń

    2008-01-01

    The ‘full sleeve’ construction has been designed and accomplished in the horizontal cold-chamber pressure die casting machine. Main part of this solution is a counter plunger placed in a movable die half which allows for full filling of the shot sleeve and precisely fixes the metal quantity needed for casting. The purpose of this new construction solution is mainly the reduction of the casting porosity caused by air entrapment and the improvement of both castability and accuracy of the die ca...

  20. Modeling the Time-to Corrosion Cracking of the Cover Concrete in Chloride Contaminated Reinforced Concrete Structures

    OpenAIRE

    Liu, Youping

    1996-01-01

    Significant factors on steel corrosion in chloride contaminated reinforced concrete and time-to-corrosion cracking were investigated in this study. Sixty specimens were designed with seven admixed chloride contents, three concrete cover depths, two reinforcing steel bar diameters, two exposure conditions, and a typical concrete with water to cement ratio of 0.45. Corrosion current density (corrosion rate), corrosion potential, ohmic resistance of concrete and temperature were measured monthly...

  1. 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.

  2. 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).

  3. 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.

  4. 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.

  5. Prestressed BFRP tendons in concrete beams

    OpenAIRE

    Björgvin Smári Jónsson

    2011-01-01

    Concrete structures are normally reinforced with steel tendons. In marine or chemical environment steel has its limitations. Replacing steel with FRP reinforcement has been practiced for many years but using basalt fiber reinforcement polymer tendons (BFRP) as a structural material is rather new. Tension strength of BFRP tendon is about twice the tension strength of steel reinforcement but the elastic modulus is only 40-50 GPa while steel has 200 GPa. Therefore elastic lengthening of BFRP ten...

  6. 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...

  7. Transverse Reinforcement in Reinforced Concrete Columns

    Science.gov (United States)

    Gramblička, Štefan; Veróny, Peter

    2013-11-01

    In the article we are dealing with the influence of transverse reinforcement to the resistance of a cross-section of the reinforced concrete columns and also with the effective detailing of the column reinforcement. We are verifying the correctness of design guides for detailing of transverse reinforcement. We are also taking into account the diameter of stirrups and its influence over transverse deformation of column.

  8. Radionuclide Retention in Concrete Waste Forms

    Energy Technology Data Exchange (ETDEWEB)

    Mattigod, Shas V.; Bovaird, Chase C.; Wellman, Dawn M.; Wood, Marcus I.

    2010-09-30

    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 waste form performance is affected by the full range of environmental conditions within the disposal facility; the process of waste form aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of waste form 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 waste forms come in contact with groundwater. The information presented in the report provides data that 1) quantify radionuclide retention within concrete waste form materials similar to those used to encapsulate waste in the Low-Level Waste Burial Grounds (LLBG); 2) measure the effect of concrete waste form properties likely to influence radionuclide migration; and 3) quantify the stability of uranium-bearing solid phases of limited solubility in concrete.

  9. 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...

  10. 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.

  11. 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.

  12. 59Fe distribution in continuously cast aluminium strip

    International Nuclear Information System (INIS)

    The problems are discussed of the homogeneity of continuously cast aluminium strips by horizontal casting. Theoretically discussed are phenomena present during primary solidification, namely the nonhomogeneous distribution of admixtures and impurities in primary solidified dendritic cells. A survey is given of the distribution of coefficients of basic admixtures and impurities in aluminium. Experimental investigation was carried out within the verification of theoretical research results, of the distribution of iron in continuously cast aluminium strips using radioactive iron 59Fe in form of radioactive foundry alloy containing 1.8% 59Fe. (author). 13 figs., 1 tab

  13. 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.

  14. 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...

  15. Evolution of microstructure in centrifugal cast Al-Cu alloy

    Directory of Open Access Journals (Sweden)

    Sui Yanwei

    2010-02-01

    Full Text Available In this research, the effects of centrifugal radius and mould rotation speed on microstructure in centrifugal-cast Al-Cu alloy have been investigated. The results show that, with increase of the centrifugal radius or mould rotation speed, the grain size of centrifugal-cast Al-Cu alloy decreases gradually, while the content of white phases containing the Al2Cu precipitated from α-phase, divorced eutectic and regular eutectic microstructure increases, leading to higher Cu macrosegregation. The variation level of microstructure in centrifugal-cast Al-Cu alloy at 600 rpm of mould rotation speed is greater than that at 300 rpm.

  16. Optical storage properties in cast films of an azopolymer

    Directory of Open Access Journals (Sweden)

    Neves Ubaldo Martins das

    2003-01-01

    Full Text Available In this paper we discuss the properties of optically induced birefringence in DR19-MDI cast films that may be used in optical storage applications. The selection of DR19-MDI cast films was based on a comparative study of optical storage properties of Langmuir-Blodgett (LB films from various azopolymers. DR19-MDI possesses a high residual fraction of optical birefringence and good environmental stability, which was corroborated by the data from optical storage experiments. DR19-MDI cast films maintain a reasonable level of birefringence after the initial decay due to chromophore relaxation, thus making them promising candidates for optical storage devices.

  17. Fibre reinforced self-compacting concrete flow simulations in comparison with l-box experiments using carbopol

    DEFF Research Database (Denmark)

    Svec, Oldrich; Skocek, Jan; Olesen, John Forbes;

    An evolution of distribution and orientation of fibres in the fibre reinforced self-compacting concrete during the casting process is an important matter as the final orientation and distribution of fibres can significantly influence mechanical properties of the structural elements. A two...... conducted and analysed by means of digital image analysis. Orientation tensor fields coming from the digital image analysis were compared with the simulation to verify the ability of the model to properly represent the flow of the fibre reinforced self-compacting concrete....

  18. 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...

  19. Place and dialect levelling in Denmark

    DEFF Research Database (Denmark)

    Monka, Malene

    , informants’ languages featured substantial amounts of dialect features (Kristensen 1980; Pedersen 1986). In 2005 to 2010, researchers at the Danish National Research Center for Language Change in Real Time (LANCHART) and the University of Southern Denmark re-interviewed informants, thus providing data for......) – but also to place effects, i.e. the ensemble of sociolinguistic conditions within speech localities (Horvath and Horvath 2001; Britain 2009; Blommaert 2010). This paper examines the impact of social and structural factors of place (historic, demographic, and socio-economic) (e.g. Britain 2002) as well...... as phenomenological factors (conceptualizations of place, sense of belonging and sense of place) (Johnstone 2010; Quist 2010; Jørgensen, Fallov et al. 2011) on language change in real time. Social and structural factors of place may explain why conceptualizations of – and perceived relations between...

  20. A dynamic control water distribution model of steel in continuous casting

    International Nuclear Information System (INIS)

    After investigation in many continuous casting shop of steel, a dynamic water distribution model is proposed for flexible control on secondary cooling in continuous casting. In this model, the water cooling intensity is determined by the model casting speed instead of the real casting speed. When the casting speed is steady, the model casting speed is equal to the real casting speed. When the real casting speed is changing, the model casting speed according to calculating algorithm to adjust and approaches to the real one, but there is a time delay between them, so it can avoid the slab surface temperature fluctuated due to casting speed changes. The secondary cooling can be dynamically controlled by monitoring the model casting speed. The compare of the simulation results and the measured results reveals that the temperature field and thickness of slab shell in simulations agree very well with the real production situations.

  1. Corrosion of steel in concrete in cooling water walls. Report part 3 - Corrosion of steel in water saturated concrete

    International Nuclear Information System (INIS)

    It is a well known fact that for concrete structures exposed to water the splash zone exhibit the greatest risk for corrosion on the reinforcement. Chloride ions are enriched and the supply of oxygen is good. Below the water table reported corrosion damages are few. The threshold for chloride content is in most cases exceeded but the propagation rate is low due to slow diffusion rate of oxygen in water saturated concrete. Despite this, ongoing corrosion of reinforcement has been observed in cooling water systems at the Swedish nuclear power plants. The aim of this project has been to identify and qualitatively quantify the importance of different possible mechanisms involved in corrosion of reinforcement in water saturated concrete. This has been achieved by collecting experiences, literature survey, modelling, theoretical calculations, experimental investigations as well as field measurements. The investigations have resulted in several new findings. The following have been concluded: In water saturated concrete, without the existence of macro cells, the reinforcement corrodes in an active state but with a very low rate. This active corrosion proceeds independently of the chloride content of the concrete. The corrosion rate is low even with thin concrete cover and most probably even if the concrete has been leached. Nor does high velocity of the cooling water create serious attacks. Inspections have unveiled attacks of reinforcement corrosion in the splash zone, in walls externally exposed to air and in the vicinity to pumps. In the splash zone the attacks occur above the water level. The absence of a macro cell resulting in increased corrosion on parts below the water line is of subordinate importance and is judged being without practical influence. The corrosion takes place where the environmental conditions are optimal. The same is valid for walls externally exposed to air. The macro cell is of subordinate importance. In the vicinity of pumps, observed

  2. 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

  3. 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...

  4. Irradiation response of delta ferrite in as-cast and thermally aged cast stainless steel

    Science.gov (United States)

    Li, Zhangbo; Lo, Wei-Yang; Chen, Yiren; Pakarinen, Janne; Wu, Yaqiao; Allen, Todd; Yang, Yong

    2015-11-01

    To enable the life extension of Light Water Reactors (LWRs) beyond 60 years, it is critical to gain adequate knowledge for making conclusive predictions to assure the integrity of duplex stainless steel reactor components, e.g. primary pressure boundary and reactor vessel internal. Microstructural changes in the ferrite of thermally aged, neutron irradiated only, and neutron irradiated after being thermally aged cast austenitic stainless steels (CASS) were investigated using atom probe tomography. The thermal aging was performed at 400 °C for 10,000 h and the irradiation was conducted in the Halden reactor at ˜315 °C to 0.08 dpa (5.6 × 1019 n/cm2, E > 1 MeV). Low dose neutron irradiation at a dose rate of 5 × 10-9 dpa/s was found to induce spinodal decomposition in the ferrite of as-cast microstructure, and further to enhance the spinodal decomposition in the thermally aged cast alloys. Regarding the G-phase precipitates, the neutron irradiation dramatically increases the precipitate size, and alters the composition of the precipitates with increased, Mn, Ni, Si and Mo and reduced Fe and Cr contents. The results have shown that low dose neutron irradiation can further accelerate the degradation of ferrite in a duplex stainless steel at the LWR relevant condition.

  5. 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...

  6. Possibilities of implementing bimetallic hammer castings in crushing industries

    Directory of Open Access Journals (Sweden)

    S. Žic

    2009-01-01

    Full Text Available For decades manganese steel casts have been most used materials for manufacturing elements subjected to impact and high stress abrasion. These materials are used in countless industrial applications that involve crushing of raw material by impact. Some of most important characteristics of manganese cast steels are work-hardening and high strength. Opposite from manganese steels, highly alloyed white cast irons are materials with high amount of hard carbide phases that shows better abrasion resistance but have lower strength and impact energy. Aim of this paper is to investigate possibilities to reduce costs and maintenance periods by implementing bimetallic materials.

  7. Eventful places in the 2011 movements

    DEFF Research Database (Denmark)

    Risager, Bjarke Skærlund

    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......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......’ 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...

  8. Effects of GFF Bands on Normal and High Strength Concrete Cylinders

    OpenAIRE

    J. Jayaprakash; Abdul Aziz Abdul Samad; Noridah Mohamad; Choong, K.K.; M.J. Megat Azmi; H.A.B. Badorul

    2010-01-01

    This paper exemplifies the effects of externally confined Glass Fibre Fabric (GFF) bands on normal and high strength concrete cylinders. Twelve normal and high strength concrete cylinders were cast and tested in the laboratory environment under axial compression to failure. The experimental results show that the degree of confinement of discrete GFF confined high strength concrete cylinders was significantly better than normal strength concrete cylinders with GFF bands, however...

  9. 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.

  10. 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

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

    International Nuclear Information System (INIS)

    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-ZrO2) 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. Preliminary results

  12. 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...

  13. 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.

  14. In-place HEPA filter penetration test

    International Nuclear Information System (INIS)

    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

  15. 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..

  16. Electrokinetic decontamination of concrete

    International Nuclear Information System (INIS)

    Concrete structures which have been contaminated with uranium and other radioisotopes may be decontaminated using in-situ electrokinetic remediation. By placing an electrode cell on the concrete surface and using the concrete's rebar, a ground rod, or another surface cell as the counter electrode, the radioisotopes may be migrated from the concrete into this cell. The process is highly dependent upon the chemical parameters of the species involved; namely, the concrete, the contaminants, and the solubilizers used to mobilize the contaminants. In a preliminary study conducted at the K-25 Site of the Oak Ridge National Labs, an estimated removal of >40 percent of uranium has been observed for a short duration run. This removal occurred using traditional uranium solubilizers in contact with the contaminated surface

  17. Concretization of high level radioactive source in marine sediment

    International Nuclear Information System (INIS)

    A method is described of forming a concretized coating which encapsulates a canister of heat producing materials and provides protection against corrosion by seawater when the canister is placed in an ocean floor-sediment environment. The method comprises: selecting a location on the ocean floor at such a depth that the proximate seawater thereat would be capable of reaching a temperature of at least 1100C. when in contact with the canister of heat producing materials. The seawater within the pores of the ocean floor sediment thereat contains sufficient amounts of calcium and sulfate to form, at the temperature, an anhydrite layer around the canister; placing the canister into the ocean floor sediment at the location; and storing the canister at the location for at least one month thereby allowing heat from the canister to raise the temperature of the seawater in the pores of the sediment proximate to the canister to at least 1100C. wherein anhydrite precipitates from the proximate seawater and forms a concretized layer on the exterior surfaces of the canister

  18. 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...

  19. 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

  20. 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

  1. 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.

  2. 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 ...

  3. Social interactions affecting caste development through physiological actions in termites

    Directory of Open Access Journals (Sweden)

    DaiWatanabe

    2014-04-01

    Full Text Available A colony of social insects is not only an aggregation of individuals but also a functional unit. To achieve adaptive social behavior in fluctuating environmental conditions, in addition to coordination of physiological status in each individual, the whole colony is coordinated by interactions among colony members. The study on the regulation of social-insect colonies is termed “social physiology”. Termites, a major group of social insects, exhibit many interesting phenomena related to social physiology, such as mechanisms of caste regulation in a colony. In their colonies, there are different types of individuals, i.e., castes, which show distinctive phenotypes specialized in specific colony tasks. Termite castes comprise reproductives, soldiers and workers, and the caste composition can be altered depending on circumstances. For the regulation of caste compositions, interactions among individuals, i.e. social interactions, are thought to be important. In this article, we review previous studies on the adaptive meanings and those on the proximate mechanisms of the caste regulation in termites, and try to understand those comprehensively in terms of social physiology. Firstly, we summarize classical studies on the social interactions. Secondly, previous studies on the pheromone substances that mediate the caste regulatory mechanisms are overviewed. Then, we discuss the roles of a physiological factor, juvenile hormone (JH in the regulation of caste differentiation. Finally, we introduce the achievements of molecular studies on the animal sociality (i.e. sociogenomics in terms of social physiology. By comparing the proximate mechanisms of social physiology in termites with those in hymenopterans, we try to get insights into the general principles of social physiology in social animals.

  4. 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 ...

  5. 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.)

  6. 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...

  7. 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.

  8. 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...

  9. Estimation of primary dendrite arm spacings in continuous casting products

    Energy Technology Data Exchange (ETDEWEB)

    Cicutti, C. [Centro de Investigacion Industrial-FUDETEC, Campana (Argentina); Bilmes, P.; Boeri, R.

    1997-09-01

    The proportion of steels produced by continuous casting has grown drastically during the last two decades, increasing to such an extent that in some countries, several grades of steel are exclusively made by this process. Many investigations recognized the significant influence of the solidification structure on the quality of cast products, and pointed out the importance of the development of appropriate tools to predict the microstructure as a function of thermal and physical parameters. The estimation of secondary dendrite arm spacings in continuously cast steel products has received some attention. However, very little effort has been focused on the prediction of primary dendrite arm spacings, to the best of the authors` knowledge. The main objective of this study is to develop simple expressions to estimate the variation of primary dendrite arm spacings through the section of continuous casting steel products.

  10. 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...

  11. Consumer views about aging-in-place

    OpenAIRE

    Grimmer K; Kay D; Foot J; Pastakia K

    2015-01-01

    Karen Grimmer, Debra Kay, Jan Foot, Khushnum PastakiaInternational Center for Allied Health Evidence, Sansom Institute, City East Campus, University of South Australia, Adelaide, SA, AustraliaBackground: Supporting older people’s choices to live safely and independently in the community (age-in-place) can maximize their quality of life and minimize unnecessary hospitalizations and residential care placement. Little is known of the views of older people about the aging-in-place process, ...

  12. 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.

  13. STRENGTH SHRINKAGE AND CREEP OF CONCRETE IN TENSION AND COMPRESSION

    OpenAIRE

    S A Kristiawan

    2006-01-01

    Strength, shrinkage and creep of concrete in tension and compression have been determined and the relationship between those properties was studied. Direct tensile tests were applied to measure those properties in tension. The relationship of creep in tension and compression was determined based on the measurement of creep at similar stress and similar stress/strength ratio. It is found that concrete deforms more in tension than in compression. Except for concrete with a higher water/cement r...

  14. Considering place in community health nursing.

    Science.gov (United States)

    Bender, Amy; Clune, Laurie; Guruge, Sepali

    2009-03-01

    When a geographic location is assigned meaning, it becomes a place. The authors argue that place matters as both geographical location and lived experience.They extend the current conceptualization of nursing geography to encompass community health nursing and address intricacies of community nursing practice and research that often go unnoticed. They do so by exploring the notion of place in home and community, including the structural/spatial dimensions of the nurse-client relationship. The authors review the health geography literatures, then discuss the implications for practice and research in community health. They invite community health nurses to critically examine their practice and research with reference to such issues as the power of the nurse, marginalized places as determinants of health, and how best to care for clients living in diverse community settings. PMID:19485049

  15. 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...

  16. 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.

  17. 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.

  18. Worker caste determination in the army ant Eciton burchellii

    OpenAIRE

    Jaffé, Rodolfo; Kronauer, Daniel J. C.; Bernhard Kraus, F; Boomsma, Jacobus J.; Robin F A Moritz

    2007-01-01

    Elaborate division of labour has contributed significantly to the ecological success of social insects. Division of labour is achieved either by behavioural task specialization or by morphological specialization of colony members. In physical caste systems, the diet and rearing environment of developing larvae is known to determine the phenotype of adult individuals, but recent studies have shown that genetic components also contribute to the determination of worker caste. One of the most ext...

  19. High Performance Concrete (HPC)

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Normal Strength Concrete (NSC) is heavy and lacks the required workability in some large concrete structures, such as high-rise buildings, bridges, and structures under severe exposure conditions. High Performance Concrete (HPC) is the latest development in concrete.

  20. 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...

  1. The rehabilitation of concrete dams in Ontario

    International Nuclear Information System (INIS)

    Rehabilitation alternatives for Ontario's large inventory of concrete dams, many of them constructed in the early part of this century, were discussed. Although many of these dams have undergone varying degrees of rehabilitation and updating over the years, many of them are again in need of replacement or major rehabilitation. Details of the field and laboratory investigations involved in a detailed condition assessment are described, and the approach is illustrated with two case histories, one involving a dam near Sudbury (Coniston Generating Station, constructed in 1935), the other near Cobalt (Matabitchuan Generating Station, constructed in 1909). 10 refs., 2 figs

  2. Developments in Performance Monitoring of Concrete Exposed to Extreme Environments.

    OpenAIRE

    McCarter, W.J.; Chrisp, T. M.; Starrs, G.; Adamson, A.; Owens, E.; Basheer, P.A.M.; Nanukuttan, S. V.; Srinivasan, S; Holmes, Niall

    2011-01-01

    The performance of the surface zone of concrete is acknowledged as a major factor governing the rate of deterioration of reinforced concrete structures because it provides the only barrier to the ingress of water containing dissolved ionic species such as chlorides, which ultimately initiate corrosion of the reinforcement. In situ monitoring of cover-zone concrete is therefore critical in attempting to make realistic predictions as to the in-service performance of the structure. To this end, ...

  3. 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 ...

  4. HETEK - Control of Early Age Cracking in Concrete

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Christensen, Søren Lolk; Dela, Birgitte Friis;

    1997-01-01

    This report deals with autogenous shrinkage of two concretes and the corresponding mortars. The theory of self-desiccation and autogenous deformation is presented. Autogenous shrinkage of mortar is measuredin a paste dilatometer at constant and varying temperatures. Similarly the autogenous shrin...... shrinkage of the concrete is measured in a concrete dilatometer developed in this project. The results are discussed in relation to thermal expansion, activation energy and maturity transformation....

  5. 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...

  6. 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...

  7. Corrosion of reinforcement bars in steel ibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Solgaard, Anders Ole Stubbe

    perpendicular to the reinforcement bar) was reduced for SFRC compared to plain concrete, whereas there was no clear impact on the slip at the concrete/steel-bar (displacement discontinuity parallel to the reinforcement bar) caused by the steel fibres. Additional experimental and numerical studies concerning......Steel fibres have been known as an alternative to traditional reinforcement bars for special applications of structural concrete for decades and the use of steel fibre reinforced concrete (SFRC) has gradually increased in recent years. Steel fibres lead to reduced crack widths in concrete formed......, among other reasons, due to shrinkage and/or mechanical loading. Steel fibres are nowadays also used in combination with traditional reinforcement for structural concrete, where the role of the fibres is to minimize the crack widths whereas the traditional reinforcement bars are used for structural...

  8. Damage detection monitoring applications in self-healing concrete structures using embedded piezoelectric transducers and recovery

    Science.gov (United States)

    Karaiskos, G.; Tsangouri, E.; Aggelis, D. G.; Deraemaeker, A.; Van Hemelrijck, D.

    2015-07-01

    The ageing, operational and ambient loadings have a great impact in the operational and maintenance cost of concrete structures. Their service life prolongation is of utmost importance and this can be efficiently achieved by using reliable and low-cost monitoring and self-healing techniques. In the present study, the ultrasonic pulse velocity (UPV) method using embedded small-size and low-cost piezoelectric PZT (lead zirconate titanate) ceramic transducers in concrete with self-healing properties is implemented for monitoring not only the setting and hardening phases of concrete since casting time, but also for the detection of damage initiation, propagation and recovery of integrity after healing. A couple of small-scale notched unreinforced concrete beams are subjected to mode-I fracture through three-point bending tests. After a 24-hour healing agent curing period, the beams are reloaded using the same loading scenario. The results demonstrate the excellent performance of the proposed monitoring technique during the hydration, damage generation and recovery periods.

  9. Responses in concrete cylinders under severe thermal loads

    International Nuclear Information System (INIS)

    The numerical results indicate that the thermal gradient significantly influences the rate of pore pressure buildup and the drying rate in a hollow concrete cylinder exposed to high temperature environments on the inner surface and the surrounding atmosphere on the outer surface. The higher the rate of the concrete surface temperature rise, the higher the rate of the pore pressure build up and the higher the drying rate of the concrete. The higher the rate of surface temperature rise, the closer the location of the maximum pore pressure peak to the heated inner surface. Due to the moisture clog and high values of the pore pressure buildup in the clogged region beneath the heated surface of the concrete hollow cylinder, explosive spallings and cracks of the concrete are expected as the stress generated by the pore pressure exceed the concrete tensile strength. (author)

  10. Service life of concrete

    International Nuclear Information System (INIS)

    The US Nuclear Regulatory Commission (NRC) has the responsibility for developing a strategy for the disposal of low-level radioactive waste (LLW). An approach being considered for their disposal is to place the waste forms in concrete vaults buried in the earth. A service life of 500 years is required for the concrete vaults as they may be left unattended for much of their lives. This report examines the basis for making service life predictions based on accelerated testing and mathematical modeling of factors controlling the durability of concrete buried in the ground. Degradation processes are analyzed based on considerations of their occurrence, extent of potential damage, and mechanisms. A recommended research plan for developing methods for predicting the service life of concrete is presented. The major degradation processes that concrete of underground vaults will likely encounter are sulfate attack, corrosion of reinforcing steel, alkali-aggregate reactions, and leaching by ground water. Freezing and thawing damage could occur before the vaults are covered with soil and therefore are addressed. Other degradation processes which may occur are microbiological attack, salt crystallization, and attack by LLW, especially by acidic materials. Two important factors controlling the resistance of concrete to these degradation processes are its quality and permeability. Concepts of quality and factors affecting quality of concrete are discussed. Permeability is discussed in terms of the water-to-cement ratio, the pore structure of concrete, and the effects of cracks. 101 refs., 15 figs., 5 tabs

  11. Neutron activation measurements in research reactor concrete shield

    International Nuclear Information System (INIS)

    The results of activation measurement inside TRIGA research reactor concrete shielding are given. Samples made of ordinary and barytes concrete together with gold and nickel foils were irradiated in the reactor body. Long-lived neutron-induced gamma-ray-emitting radioactive nuclides in the samples were measured with HPGe detector. The most active longlived radioactive nuclides in ordinary concrete samples were found to be 60Co and 152Eu and in barytes concrete samples 60Co, 152Eu and 133Ba. Measured activity density of all nuclides was found to decrease almost linearly with depth in logarithmic scale.(author)

  12. STRENGTH SHRINKAGE AND CREEP OF CONCRETE IN TENSION AND COMPRESSION

    Directory of Open Access Journals (Sweden)

    S A Kristiawan

    2006-01-01

    Full Text Available Strength, shrinkage and creep of concrete in tension and compression have been determined and the relationship between those properties was studied. Direct tensile tests were applied to measure those properties in tension. The relationship of creep in tension and compression was determined based on the measurement of creep at similar stress and similar stress/strength ratio. It is found that concrete deforms more in tension than in compression. Except for concrete with a higher water/cement ratio, the use of pulverised fuel ash, ground granulated blast furnace slag, superplasticizer and shrinkage reducing admixture has no effect on strength. However, they affect creep and shrinkage of concrete.

  13. 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...

  14. 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...

  15. Ultrasonic Pulse Velocity Versus Strength For Concrete In Qatar

    OpenAIRE

    Abdul Salam, M. A.

    1992-01-01

    Compressive strength of concrete is widely accepted as a characteristic property indicating and representing its quality. The accuracy of both ultrasonic and mechanical strength is discussed and the advantages of ultrasonic testing are pointed out. Measurements of ultrasonic pulse velocity and mechanical crushing load of concrete cubes made from the aggregate and cement used in the State of Qatar are reported in this paper. Measurements on concrete cores from a local structure are also report...

  16. 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 ...

  17. 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...

  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. Role of technological service in the production of concrete

    International Nuclear Information System (INIS)

    The principles are summed up of quality assurance in concrete production and of technology services operations. Compression strength is the basic concrete property being monitored. Regular assessment of cube strength can be computer-aided. One test is performed per 100 m3 of production. Also concrete strength in structures is determined, this either using bodies removed from the structures or using nondestructive tests. (M.D.). 3 refs

  20. Innovation in concrete research-review and perspective

    International Nuclear Information System (INIS)

    The heritage of concrete making as a craft has made testing of laboratory specimens the basic principle for research and standard control systems; this has corresponded well with the conditions for field concrete technology and structural performance throughout the 19th and the first half of the 20th centuries' developments. New demands for concrete in the wake of World War II made tremendous development possible for the cement and concrete industries. However, deleterious reactions in field concrete appeared in many countries over the next decades, among other reasons because the laboratory testing systems were preserved without recognition that rates and intensity of the reactions in the actual concrete caused changes of the processes, which did not occur in the test samples. That made the reproducibility of the tests incompatible with the sought predictability for the properties of the concrete. In recent years, senior scientists have commenced to caution that the ordinary laboratory tests do not reliably simulate the behavior of concrete in the field. Besides, fractal appearance of micro- and macrostructures in concrete has been reported in international research journals. Meanwhile, progress in the natural sciences with the introduction of the chaos theory has made it possible to investigate turbulence, i.e. nonlinear processes in Nature and their visual fractal patterns

  1. Temperature field in concrete when in contact with hot liquids

    International Nuclear Information System (INIS)

    In an HCDA (Hypothetical Core Disruptive Accident) it is postulated that liquid metal coolants and core materials come in contact with the retaining concrete structure. A mathematical model and an associated computer program was previously developed to describle the transient heat and mass transfer in the concrete. Implementations on the original program-USINT- are included to consider the variations of the thermal conductivity as a function of the temperature. Also a subroutine - PLOTTI - is incorporated to the program for the plotting of the results. The new program - USINTG - is used to calculate the temperature and pressure fields and the water released from concrete structures during a sodium leak simulation and with the concrete structures in contact with liquid sodium. No consideration about chemical reactions involving the sodium when in contact with concrete is considered. (Author)

  2. Consumer views about aging-in-place

    Directory of Open Access Journals (Sweden)

    Grimmer K

    2015-11-01

    Full Text Available Karen Grimmer, Debra Kay, Jan Foot, Khushnum PastakiaInternational Center for Allied Health Evidence, Sansom Institute, City East Campus, University of South Australia, Adelaide, SA, AustraliaBackground: Supporting older people’s choices to live safely and independently in the community (age-in-place can maximize their quality of life and minimize unnecessary hospitalizations and residential care placement. Little is known of the views of older people about the aging-in-place process, and how they approach and prioritize the support they require to live in the community accommodation of their choice.Purpose: To explore and synthesize the experiences and perspectives of older people planning for and experiencing aging-in-place.Methods: Two purposively sampled groups of community-dwelling people aged 65+ years were recruited for individual interviews or focus groups. The interviews were semistructured, audio-recorded, and transcribed. Themes were identified by three researchers working independently, then in consort, using a qualitative thematic analysis approach.Results: Forty-two participants provided a range of insights about, and strategies for, aging-in-place. Thematic saturation was reached before the final interviews. We identified personal characteristics (resilience, adaptability, and independence and key elements of successful aging-in-place, summarized in the acronym HIPFACTS: health, information, practical assistance, finance, activity (physical and mental, company (family, friends, neighbors, pets, transport, and safety.Discussion: This paper presents rich, and rarely heard, older people’s views about how they and their peers perceive, characterize, and address changes in their capacity to live independently and safely in the community. Participants identified relatively simple, low-cost, and effective supports to enable them to adapt to change, while retaining independence and resilience. The findings highlighted how successful

  3. 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.

  4. 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. ...

  5. Durability of GFRP reinforcing bars and their bond in concrete

    OpenAIRE

    ROLLAND, Arnaud; Chataigner, Sylvain; QUIERTANT, Marc; Benzarti, Karim; Argoul, Pierre

    2015-01-01

    The use of composite reinforcing bars (rebars) for the reinforcement of concrete appears as an attractive solution to prevent corrosion, which is the main pathology encountered on concrete structures. Although such rebars are being used for more than ten years, there is a clear lack of knowledge regarding their durability, especially under alkaline environment. This paper aims at investigating the evolutions of tensile properties and bond in concrete of GFRP (Glass Fiber Reinforced Polymer...

  6. Comparison of different forms of gravel as aggregate in concrete

    OpenAIRE

    Sikiru ORITOLA; Abd. Latif SALEH; Abdul Rahman MOHD SAM

    2014-01-01

    Gradation plays an important role in the workability, segregation, and pump ability of concrete. Uniformly distributed aggregates require less paste which will also decrease bleeding, creep and shrinkage while producing better workability, more durable concrete and higher packing. This attempt looks at the effect of particle size distribution pattern for five types of gravel aggregate forms, angular, elongated, smooth rounded, irregular and flaky as related to the strength of concrete produce...

  7. 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...

  8. Prevention of shrinkage cracking in tight concrete structures

    International Nuclear Information System (INIS)

    It is shown that crack formation and propagation in concrete members subjected to restrained shrinkage can be realistically predicted by means of a comprehensive approach including a diffusion analysis and fracture mechanics considerations. The conditions for stable crack propagation regarding dimensions of the concrete member, degree of restraint to the imposed deformation and material properties are discussed. Guidelines on the prevention of shrinkage cracking of concrete structures are given. (author). 10 refs., 5 figs

  9. Fissuring-chemical damaging on transfers in concrete

    International Nuclear Information System (INIS)

    Concrete is a material often use in the nuclear wastes disposal. The safety analysis of a long time wastes disposal with concrete requires to verify the concrete behaviour in water. As concretes generally have cracks, it is necessary to study the crack propagation influence on chemical degradation. In this paper, the author presents diffusion tests on fissured and/or chemical aged cement. The chemical degradation of the material leads to a supplementary porosity by the hydrates decalcification and increases its diffusivity. The cracking impact is less important and can be experimentally concealed. (A.L.B.)

  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. Preferred orientation of ettringite in concrete fractures

    International Nuclear Information System (INIS)

    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.

  13. 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.

  14. 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.

  15. 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.

  16. Nodular cast iron and casting monitoring

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2008-10-01

    Full Text Available In this paper quality monitoring of nodular cast iron and casting made of it is presented. A control system of initial liquid cast iron to spheroidization, after spheroidization and inoculation with using of TDA method was shown. An application of an ultrasonic method to assessment of the graphite form and the metal matrix microstructure of castings was investigated.

  17. 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.

  18. 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...

  19. EFFECTS OF CHEMICAL ADMIXTURES ON SPECIALITIES OF HARDENED CONCRETE USED IN READY CONCRETE PRODUCTION IN ESKİŞEHİR

    Directory of Open Access Journals (Sweden)

    İlker Bekir TOPÇU

    2006-01-01

    Full Text Available In this study polls were taken from different ready mixed concrete firms in Eskişehir. Chemical admixtures used in concrete production were investigated according to the polls, and some information about chemical admixtures was obtained. Compressive strengths of concrete specimens manufactured by ready mixed concrete firms were evaluated, and results were investigated due to different types and proportions of admixtures used in concrete. Chemical admixtures were compared to each other at the end of the investigation, and the results showed, chemical admixtures gain concrete different characteristics according to various environmental conditions. The past investigations showed that the differences between chemical admixtures were most occurred owing to environmental conditions (season, temperature etc., and chemical admixtures were classified according to seasons by users.

  20. 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.

  1. 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

  2. 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 (...

  3. Sex and Caste-Specific Variation in Compound Eye Morphology of Five Honeybee Species

    OpenAIRE

    Streinzer, Martin; Brockmann, Axel; Nagaraja, Narayanappa; Spaethe, Johannes

    2013-01-01

    Ranging from dwarfs to giants, the species of honeybees show remarkable differences in body size that have placed evolutionary constrains on the size of sensory organs and the brain. Colonies comprise three adult phenotypes, drones and two female castes, the reproductive queen and sterile workers. The phenotypes differ with respect to tasks and thus selection pressures which additionally constrain the shape of sensory systems. In a first step to explore the variability and interaction between...

  4. Additives as corrosion inhibitors in reinforced concrete

    International Nuclear Information System (INIS)

    This work studies the behavior of two additives as inhibitors of corrosion in reinforced concrete. The presence of Microsilica, a physical inhibitor, in the mixture decreases pore size in structures and improves compression. Calcium Nitrite, a chemical inhibitor, is an oxidizing agent and allows a more homogenous film to form over the steel that becomes more resistant to attacks from aggressive ions like anion chloride and others. Three pairs of concrete test pieces were used without additives and with additives with a/c ration of 0.55. The samples were exposed to an accelerated attack of chlorides, submerging them in a 4.27 M solution of NaCl for 24 hours and then drying them at room temperature for another 24 hours, completing a cycle every 48 hours. The tests were carried out at 1 cycle and 5 cycles of partial moistening and drying. The steel corrosion was evaluated with corrosion potential measurements. Conductivity, pH, chlorides and sulfate profiles were defined depending on the depth of the concrete. The composition of the corrosion products was determined using X-ray diffraction and the morphology of the film by scanning electron microscopy. The results show that for 1 test cycle, the corrosion potential of the steel in the sample with calcium nitrite was -54mV, which was a higher value than that measured in the sample with microsilica (-217.3mV) and without an additive (-159.1mV), corroborating its inhibitory power. The content of the free chlorides in the sample with micros ice allows greater capillary suction by adding high amounts of chloride to the structure (2.6% on the outside up to 2.20% near the steel); while the test pieces with calcium nitrite and without an additive had concentrations lower than 2% in all the evaluated points. After five cycles of exposing the samples to the saline solution the behavior is inverted. The measures of conductivity agreed with the previous results. Meanwhile, the pH of the solutions obtained from the powder from the

  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. 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.

  7. 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.

  8. Tritium contamination of concrete walls and floors in tritium-handling laboratory

    International Nuclear Information System (INIS)

    A tritium handling laboratory was constructed at the National Institute for Fusion Science about twenty years ago and it was recently closed down. We completed the necessary work that is legally required in Japan at the laboratory, when the use of radioisotopes is discontinued, involving measurements of radioactive contamination. We mainly used smear and direct-immersion methods for the measurements. In applying the smear method, we used a piece of filter paper to wipe up the tritium staining the surfaces. The filter paper containing the tritium was placed directly into a dedicated vial, a scintillation cocktail was then poured over it, and the tritium was measured with a liquid scintillation counter. With the direct-immersion method, a piece of concrete was placed directly into a vial containing a scintillation cocktail, and the tritium in the concrete was measured with a liquid scintillation counter. As well as these measurements, we investigated water-extraction and heating-cooling methods for measuring tritium contamination in concrete. With the former, a piece of concrete was placed into water in a tube to extract the tritium, the water containing the extracted tritium was then poured into a dedicated vial containing a scintillation cocktail, and the tritium contamination was measured. With the latter, a piece of concrete was placed into a furnace and heated to 800 degrees centigrade to vaporize the tritiated water into flowing dry air. The flowing air was then cooled to collect the vaporized tritiated water in a tube. The collected water was placed in a vial for scintillation counting. To evaluate the direct-immersion method, ratios were determined by dividing the contamination measured with the heating-cooling method by that measured with the direct-immersion method. The average ratio was about 2.5, meaning a conversion factor from contamination obtained with the direct-immersion method to that with the heating-cooling method. We also investigated the

  9. 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.

  10. Surface dosimetry for breast radiotherapy in the presence of immobilization cast material

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, Andrew; Hardcastle, Nicholas; Metcalfe, Peter; Cutajar, Dean; Quinn, Alexandra; Cardoso, Michael; Rosenfeld, Anatoly [Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW (Australia); Foo, Kerwyn [Sydney Medical School, University of Sydney, Sydney, NSW (Australia); Barlin, Sheree, E-mail: anatoly@uow.edu.au [Illawarra Cancer Care Centre, Wollongong Hospital, Wollongong, NSW (Australia)

    2011-02-21

    Curative breast radiotherapy typically leaves patients with varying degrees of cosmetic damage. One problem interfering with cosmetically acceptable breast radiotherapy is the external contour for large pendulous breasts which often results in high doses to skin folds. Thermoplastic casts are often employed to secure the breasts to maintain setup reproducibility and limit the presence of skin folds. This paper aims to determine changes in surface dose that can be attributed to the use of thermoplastic immobilization casts. Skin dose for a clinical hybrid conformal/IMRT breast plan was measured using radiochromic film and MOSFET detectors at a range of water equivalent depths representative of the different skin layers. The radiochromic film was used as an integrating dosimeter, while the MOSFETs were used for real-time dosimetry to isolate the contribution of skin dose from individual IMRT segments. Strips of film were placed at various locations on the breast and the MOSFETs were used to measure skin dose at 16 positions spaced along the film strips for comparison of data. The results showed an increase in skin dose in the presence of the immobilization cast of up to 45.7% and 62.3% of the skin dose without the immobilization cast present as measured with Gafchromic EBT film and MOSFETs, respectively. The increase in skin dose due to the immobilization cast varied with the angle of beam incidence and was greatest when the beam was normally incident on the phantom. The increase in surface dose with the immobilization cast was greater under entrance dose conditions compared to exit dose conditions.

  11. 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…

  12. 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)

  13. Manufacture of centrifugal Castings

    OpenAIRE

    Minář, Martin

    2015-01-01

    The main goal of this bachelor thesis is to collect basic information related to the production of castings by centrifugal casting. It is focused on horizontal and vertical centrigugal casting, casting of various metals and their alloys, such as zinc, aluminum, iron, steel and silumin. This technology is compared with other casting methods in terms of specific characteristics, amount of usage, production economics, advantages, disadvantages, the resulting quality of castings and other factors.

  14. Assessment of Concrete Strength Using Partial Replacement of Coarse Aggregate for Wast Tiles and Cement for Rice Husk Ash in Concrete

    Directory of Open Access Journals (Sweden)

    Umapathy U

    2014-05-01

    Full Text Available Conservation of natural resources and preservation of environment is the essence of any development. The problem arising from continuous technological and industrial development is the disposal of waste material. If some of the waste materials are found suitable in concrete making, not only cost of construction can be cut down, but also safe disposal of waste materials can be achieved. So in our project, an attempt has been made to assess the suitability of stone with waste tills in concrete making. In the laboratory tiles has been tried as coarse aggregate has been used as partial substitute to conventional coarse aggregate concrete making and today many researches are ongoing into the use of Portland cement replacements, using many waste materials like pulverized fly ash (PFA and ground granulated blast furnace slag (GGBS. Like PFA and GGBS a waste glass powder (GLP is also used as a binder with partial replacement of cement which takes some part of reaction at the time of hydration. In this study, rice husk ash have been used as partially replacements to the cement Cubes were cast and tested for compressive strength, and modulus of rupture after a curing period of 7,17,28 days.

  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. 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

  17. 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.

  18. 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.

  19. 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.

  20. [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