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.

Decision Analysis Science Modeling for Application and Fielding Selection Applied to Concrete Decontamination Technologies

International Nuclear Information System (INIS)

Ebadian, M.A.; Ross, T.L.

1998-01-01

Concrete surfaces contaminated with radionuclides present a significant challenge during the decontamination and decommissioning (D and D) process. As structures undergo D and D, coating layers and/or surface layers of the concrete containing the contaminants must be removed for disposal in such a way as to present little to no risk to human health or the environment. The selection of a concrete decontamination technology that is safe, efficient, and cost-effective is critical to the successful D and D of contaminated sites. To support U.S. Department of Energy (DOE) Environmental Management objectives and to assist DOE site managers in the selection of the best-suited concrete floor decontamination technology(s) for a given site, two innovative and three baseline technologies have been assessed under standard, non-nuclear conditions at the Hemispheric Center for Environmental Technology (HCET) at Florida International University (FIU). The innovative technologies assessed include the Pegasus Coating Removal System and Textron's Electro-Hydraulic Scabbling System. The three baseline technologies assessed include: the Wheelabrator Blastrac model 1-15D, the NELCO Porta Shot Blast trademark model GPx-1O-18 HO Rider, and the NELCO Porta Shot Blasttrademark model EC-7-2. These decontamination technology assessments provide directly comparable performance data that have previously been available for only a limited number of technologies under restrictive site-specific constraints. Some of the performance data collected during these technology assessments include: removal capability, production rate, removal gap, primary and secondary waste volumes, and operation and maintenance requirements. The performance data generated by this project is intended to assist DOE site managers in the selection of the safest, most efficient, and cost-effective decontamination technologies to accomplish their remediation objectives

Surface treatment systems for concrete in marine environment: Effect of concrete cover thickness

Directory of Open Access Journals (Sweden)

Marcelo Henrique Farias de Medeiros

Full Text Available Abstract There are some ways to extend the service life of a reinforced concrete structure. This paper focuses on the extension of the service life by treating the surface of reinforced concrete, specifically on the effect of the concrete cover thickness on the surface treatment system efficacy. Thus, chloride migration tests were performed and diffusion chloride coefficients were calculated. The service life of each case (treated or non-treated concrete was estimated using these data and Fick's second law of diffusion. Results indicated that the thicker the concrete cover is, the greater the efficacy of the concrete surface treatment system will be. The dissemination of this information is important, since it is almost intuitive to think that the effect of a surface treatment system depends only on itself and this study shows the opposite.

HYDRAULIC CONCRETE COMPOSITION AND PROPERTIES CONTROL SYSTEM

Directory of Open Access Journals (Sweden)

O. M. Pshinko

2015-08-01

Full Text Available Purpose. Scientific work aims at the development and testing of information system to meet the challenges of concrete composition design and control (for railway structures and buildings based on the physico-analytical method algorithm for hydraulic concrete composition calculation. Methodology. The proposed algorithm of hydraulic concrete composition calculation is based on the physicochemical mechanics and in particular on the rheology of elastic–viscous–plastic bodies. The system of canonical equations consists of the equations for concrete strength, absolute volume, concrete mix consistency as well as the equation for optimal concrete saturation with aggregates while minimizing cement content. The joint solution of these four equations related to composition allows determining for the materials the concrete composition of required strength, concrete workability with minimum cement content. The procedure for calculation of hydraulic concrete composition according to the physico-analytical method consists of two parts: 1 physical, which is laboratory testing of concrete mix components in different concrete compositions; 2 analytical, which represents the calculation algorithm for concrete compositions equivalent in concrete strength and workability that comply with the specific conditions of concrete placing. Findings. To solve the problem of designing the concrete composition with the desired properties for railway structures and buildings it was proposed to use the information technology in the form of a developed computer program whose algorithm includes the physico-analytical method for hydraulic concrete composition determination. Originality. The developed concrete composition design method takes into account the basic properties of raw materials, concrete mix and concrete, which are pre-determined. The distinctive feature of physico-analytical method is obtaining of a set of equivalent compositions with a certain concrete mix

Hydraulic concrete composition and properties control system

OpenAIRE

PSHINKO O.M.; KRASNYUK A.V.; HROMOVA O.V.

2015-01-01

Purpose. Scientific work aims at the development and testing of information system to meet the challenges of concrete composition design and control (for railway structures and buildings) based on the physico-analytical method algorithm for hydraulic concrete composition calculation. Methodology. The proposed algorithm of hydraulic concrete composition calculation is based on the physicochemical mechanics and in particular on the rheology of elastic–viscous–plastic bodies. The system of canon...

Evaluation of concrete recycling system efficiency for ready-mix concrete plants.

Science.gov (United States)

Vieira, Luiz de Brito Prado; Figueiredo, Antonio Domingues de

2016-10-01

The volume of waste generated annually in concrete plants is quite large and has important environmental and economic consequences. The use of fresh concrete recyclers is an interesting way for the reuse of aggregates and water in new concrete production. This paper presents a study carried out for over one year by one of the largest ready-mix concrete producers in Brazil. This study focused on the evaluation of two recyclers with distinct material separation systems, herein referred to as drum-type and rotary sieve-type equipment. They were evaluated through characterization and monitoring test programs to verify the behaviour of recovered materials (aggregates, water, and slurry). The applicability of the recovered materials (water and aggregates) was also evaluated in the laboratory and at an industrial scale. The results obtained with the two types of recyclers used were equivalent and showed no significant differences. The only exception was in terms of workability. The drum-type recycler generated fewer cases that required increased pumping pressure. The analysis concluded that the use of untreated slurry is unfeasible because of its intense negative effects on the strength and workability of concrete. The reclaimed water, pre-treated to ensure that its density is less than 1.03g/cm(3), can be used on an industrial scale without causing any harm to the concrete. The use of recovered aggregates consequently induces an increase in water demand and cement consumption to ensure the workability conditions of concrete that is proportional to the concrete strength level. Therefore, the viability of their use is restricted to concretes with characteristic strengths lower than 25MPa. Copyright © 2016 Elsevier Ltd. All rights reserved.

CONCRETE BASED ON MODIFIED DISPERSE CEMENT SYSTEM

Directory of Open Access Journals (Sweden)

D. V. Rudenko

2016-08-01

Full Text Available Purpose. The article considers definition of the bond types occurring in a modified cement concrete matrix, and the evaluation of the quality of these links in a non-uniform material to determine the geometrical and physical relationships between the structure and the cement matrix modifiers. Methodology. To achieve this purpose the studies covered the microstructure of dispersed modified concrete cement matrix, the structure formation mechanism of the modified cement concrete system of natural hardening; as well as identification of the methods of sound concrete strength assessment. Findings. The author proposed a model of the spatial structure of the concrete cement matrix, modified by particulate reinforcement crystal hydrates. The initial object of study is a set of volume elements (cells of the cement matrix and the system of the spatial distribution of reinforcing crystallohydrates in these volume elements. It is found that the most dangerous defects such as cracks in the concrete volume during hardening are formed as a result of internal stresses, mainly in the zone of cement matrix-filler contact or in the area bordering with the largest pores of the concrete. Originality. The result of the study is the defined mechanism of the process of formation of the initial strength and stiffness of the modified cement matrix due to the rapid growth of crystallohydrates in the space among the dispersed reinforcing modifier particles. Since the lack of space prevents from the free growth of crystals, the latter cross-penetrate, forming a dense structure, which contributes to the growth of strength. Practical value. Dispersed modifying cement matrix provides a durable concrete for special purposes with the design performance characteristics. The developed technology of dispersed cement system modification, the defined features of its structure formation mechanism and the use of congruence principle for the complex of technological impacts of physical

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)

Naus, D.J.

1981-05-01

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

A corrosion monitoring system for existing reinforced concrete structures.

Science.gov (United States)

2015-05-01

This study evaluated a multi-parameter corrosion monitoring system for existing reinforced concrete structures in chloride-laden service environments. The system was fabricated based on a prototype concrete corrosion measurement system that : had bee...

Decontamination technologies evaluations

International Nuclear Information System (INIS)

Tripp, J.

1996-01-01

Testing has been completed at the Idaho Chemical Processing Plant (ICPP) on in situ recyclable abrasives grit blasting, concrete cleaning (using scabbling, chemicals and electro-kinetics) and laser light ablation of metals. Several small scale tests have also been conducted with strippable coatings, CO 2 pellet blasting and various other techniques. The results of this testing is summarized in this paper

Development of structural health monitoring and early warning system for reinforced concrete system

International Nuclear Information System (INIS)

Iranata, Data; Wahyuni, Endah; Murtiadi, Suryawan; Widodo, Amien; Riksakomara, Edwin; Sani, Nisfu Asrul

2015-01-01

Many buildings have been damaged due to earthquakes that occurred recently in Indonesia. The main cause of the damage is the large deformation of the building structural component cannot accommodate properly. Therefore, it is necessary to develop the Structural Health Monitoring System (SHMS) to measure precisely the deformation of the building structural component in the real time conditions. This paper presents the development of SHMS for reinforced concrete structural system. This monitoring system is based on deformation component such as strain of reinforcement bar, concrete strain, and displacement of reinforced concrete component. Since the deformation component has exceeded the limit value, the warning message can be sent to the building occupies. This warning message has also can be performed as early warning system of the reinforced concrete structural system. The warning message can also be sent via Short Message Service (SMS) through the Global System for Mobile Communications (GSM) network. Hence, the SHMS should be integrated with internet modem to connect with GSM network. Additionally, the SHMS program is verified with experimental study of simply supported reinforced concrete beam. Verification results show that the SHMS has good agreement with experimental results

Sensor Systems for Corrosion Monitoring in Concrete Structures

Directory of Open Access Journals (Sweden)

K.Kumar

2006-05-01

Full Text Available It is a need of permanently embedded corrosion monitoring devices to monitor the progress of corrosion problems on a new or existing reinforced concrete structures before embarking on repair or rehabilitation of the structures. Numerous devices are available for investigating corrosion problems, because no single technique exists which tells an engineer what he needs to know, namely how much damage there is on a structure now and how rapidly the damage will grow with time. In this investigation the studies on the sensors systems based on the measurements of half cell potential of rebars inside the concrete, resistivity of concrete, corrosion rate of rebars by eddy current measurements and sensing of chloride ions are reported. An integrated system consists of above sensors are fabricated and embedded into concrete. The response from each sensor was acquired and analyzed by NI hardware through LabVIEW software.

Use of wet concrete spraying in building technology of reinforced-concrete fiber slabs according to «Monofant» system

OpenAIRE

BUGAYEVSKIY S.

2016-01-01

Technology of cementation of reinforced-concrete slabs with non-extractable-liners for the «Monofant» system, using wet concrete spraying is implemented. A compression test for obtained columns made of fiber concrete is carried out.

Adding Concrete Syntax to a Prolog-Based Program Synthesis System

Science.gov (United States)

Fischer, Bernd; Visser, Eelco

2003-01-01

Program generation and transformation systems manipulate large, pa- rameterized object language fragments. Support for user-definable concrete syntax makes this easier but is typically restricted to certain object and meta languages. We show how Prolog can be retrofitted with concrete syntax and describe how a seamless interaction of concrete syntax fragments with an existing legacy meta-programming system based on abstract syntax is achieved. We apply the approach to gradually migrate the schemas of the AUTOBAYES program synthesis system to concrete syntax. Fit experiences show that this can result in a considerable reduction of the code size and an improved readability of the code. In particular, abstracting out fresh-variable generation and second-order term construction allows the formulation of larger continuous fragments and improves the locality in the schemas.

Development of contaminated concrete removing system 'Clean cut method'

International Nuclear Information System (INIS)

Kinoshita, Takehiko; Tanaka, Tsutomu; Funakawa, Naoyoshi; Idemura, Hajime; Sakashita, Fumio; Tajitsu, Yoshiteru

1989-01-01

In the case of decommissioning nuclear facilities such as nuclear power stations, nuclear fuel facilities and RI handling facilities and carrying out reconstruction works, if there is radioactive contamination on the surfaces of concrete structures such as the floors and walls of the buildings for nuclear facilities, it must be removed. Since concrete is porous, contamination infiltrates into the inside of concrete, and the wiping of surfaces only or chemical decontamination cannot remove it, therefore in most cases, contaminated concrete must be removed. The removal of concrete surfaces has been carried out with chipping hammers, grinders and so on, but many problems arise due to it. In order to solve these problems, the mechanical cutting method was newly devised, and clean cut method (CCRS) was completed. The depth of cutting from concrete surface is set beforehand, and the part to be removed is accurately cut, at the same time, the concrete powder generated is collected nearly perfectly, and recovered into a drum. The outline of the method and the constitution of the system, the features of the clean cut method, the development of the technology for cutting concrete and the technology for recovering concrete powder, and the test of verifying decontamination are reported. (K.I.)

Structural Precast Concrete Handbook

DEFF Research Database (Denmark)

Kjærbye, Per Oluf H

Structural concept for precast concrete systems. Design og precast reinforced concrete components. Design of precast concrete connections. Illustrations on design of precast concrete buildings. Precast concrete assembly.......Structural concept for precast concrete systems. Design og precast reinforced concrete components. Design of precast concrete connections. Illustrations on design of precast concrete buildings. Precast concrete assembly....

DISPATCHING CONTROL SYSTEM OF THE CONCRETE BATCHING PLANTS

Directory of Open Access Journals (Sweden)

Andrey Vladimirovich Ostroukh

2015-09-01

Full Text Available This paper proposes an approach to the design of dispatching control system of the concrete batching plant, which is a set of hardware maintenance, information, mathematical and software for control of technological objects. The proposed system is scalable and can include a control subsystem of mobile concrete plant, laboratory, subsystems, access control, and personnel management jobs. The system provides optimum automating the collection and processing of information for generating control signals and transmitting them without loss and distortion to the actuators in order to achieve the most efficient operation of process control object as a whole.

Precast concrete pavement - systems and performance review

Science.gov (United States)

Novak, Josef; Kohoutková, Alena; Křístek, Vladimír; Vodička, Jan

2017-09-01

Long-term traffic restrictions belong to the key disadvantages of conventional cast-in-plane concrete pavements which have been used for technical structures such as roads, parking place and airfield pavements. As a consequence, the pressure is put on the development of such systems which have short construction time, low production costs, long-term durability, low maintenance requirements etc.. The paper presents the first step in the development of an entirely new precast concrete pavement (PCP) system applicable to airfield and highway pavements. The main objective of the review of PCP systems is to acquire a better understanding of the current systems and design methods used for transport infrastructure. There is lack of information on using PCP systems for the construction of entirely new pavements. To most extensive experience is dated back to the 20th century when hexagonal slab panels and system PAG were used in the Soviet Union for the military airfields. Since cast-in-situ pavements became more common, the systems based on precast concrete panels have been mainly utilized for the removal of damaged sections of existing structures including roads, highways etc.. Namely, it concerns Fort Miller Super Slab system, Michigan system, Uretek Stitch system and Kwik system. The presented review indicates several issues associated with the listed PCP systems and their applications to the repair and rehabilitation of existing structures. Among others, the type of manufacturing technology, particularly the position of slots for dowel bars, affects the durability and performance of the systems. Gathered information serve for the development of a new system for airfield and highway pavement construction.

Control system design for concrete irrigation channels

OpenAIRE

Strecker, Timm; Aamo, Ole Morten; Cantoni, Michael

2017-01-01

Concrete channels find use at the periphery of irrigation networks, for expansion and to replace small earthen channels given the relative ease of maintenance and elimination of seepage losses. In design, it is important to account for control system performance when dimensioning the channel infrastructure. In this paper, the design of a distributed controller is investigated in terms managing water-levels, and thereby the depth profile (i.e., amount of concrete) needed to support peak flow l...

Timber-concrete composite floor systems

NARCIS (Netherlands)

Linden, M.L.R. van der; Blass, H.J.

1996-01-01

Timber-concrete composite (tcc) beams may be used for the renovation of old timber floors. Although these systems are a simple and practical solution, they are not widely adopted. One of the reasons for this is the lack of uniform design mies. In this research programme shear tests on four different

Process control system for fresh concrete preparation

International Nuclear Information System (INIS)

Bachvarov, N.; Pavlov, P.; Shukov, H.

1983-01-01

The paper discusses the principles, structure and organization of a modular microprocessor based control system, designed to be used in fresh concrete fabrication plants. The system is based on the measurement of the aggregate moisture by means of a neutron moisture meter. (author)

Development of Laser Based Remote Sensing System for Inner-Concrete Defects

Science.gov (United States)

Shimada, Yoshinori; Kotyaev, Oleg

Laser-based remote sensing using a vibration detection system has been developed using a photorefractive crystal to reduce the effect of concrete surface-roughness. An electric field was applied to the crystal and the reference beam was phase shifted to increase the detection efficiency (DE). The DE increased by factor of 8.5 times compared to that when no voltage and no phase shifting were applied. Vibration from concrete defects can be detected at a distance of 5 m from the system. A vibration-canceling system has also developed that appears to be promising for canceling vibrations between the laser system and the concrete. Finally, we have constructed a prototype system that can be transported in a small truck.

En-Vac Robotic Wall Scabbler. Innovative Technology Summary Report

International Nuclear Information System (INIS)

2001-01-01

The U.S. Department of Energy (DOE) continually seeks safer and more cost-effective technologies for use in decontamination and decommissioning (D and D) of nuclear facilities. To this end, the Deactivation and Decommissioning Focus Area (DDFA) of the DOE's Office of Science and Technology (OST) sponsors Large-Scale Demonstration and Deployment Projects (LSDDP). At these LSDDPs, developers and vendors of improved or innovative technologies showcase products that are potentially beneficial to DOE's projects and to others in the D and D community. Benefits sought include decreased health and safety risks to personnel and the environment, increased productivity, and decreased cost of operation. The Idaho National Engineering and Environmental Laboratory (INEEL) LSDDP generated a list of statements defining specific needs or problems where improved technology could be incorporated into ongoing D and D tasks. One of the stated needs was for a Robotic Wall Scabbler that would reduce costs and shorten schedules in DOE's Decommissioning Project. This demonstration investigated the associated costs and time required to remove paint from the Test Area North (TAN-607) Decontamination Shop walls by comparing the En-vac Robotic Wall Scabbler against the baseline technology. The baseline technologies consist of the Pentek Vac Pac System with the Pentek Rotopeen and Needle Gun hand-held attachments. This system only removes paint from the surface of concrete. Innovative Technology The En-vac Robotic Wall Scabbler is a remote-controlled scabbling unit with individually motor-controlled wheels that moves horizontally and vertically along floors, walls, and ceilings, adhering to the surface with the help of a high-vacuum suction created at its base (see Figures 1 and 2). The complete En-vac Blasting System consists of the En-vac robot, a recycling unit, a filter, and a vacuum unit, and uses an abrasive, steel-grit blasting technology for the scabbling process. By comparison, this

Application of expert systems in damage assessment of reinforced concrete structures

International Nuclear Information System (INIS)

Fazel Zarandi, M. H.; Sobhani, J.

2003-01-01

Expert systems are receiving great attentions in construction industry to support decision making processes in diagnostics, design, repair and rehabilitation of the structures. Although several expert systems have been examined in engineering since the 1970's, their applications in construction industry are rate. This was largely due to the lack of expert system tools available to represent the domain knowledge. Lack of flexibility, applicability, and robustness of the classical models, have forced the scientists to discover the ability of the expert systems in problem solving of civil engineering. This paper present an expert system for diagnosis the deterioration of concrete structures. This expert system emphasizes on cracking distress in reinforced concrete elements. A case study has been presented to examine and evaluate the proposed expert system. The system demonstrates a straightforward method for diagnosing the cause of reinforced concrete elements cracking

Mobile concrete solidification systems for power reactor waste

International Nuclear Information System (INIS)

Tchemitcheff, E.; Bordas, Y.

1990-01-01

In late 1988 SGN received an order from Electricite de France (EDF) for the construction of a mobile concrete solidification system to process secondary system resins generated by the P'4 and N4 series PWR power plants in France. This order was placed in view of SGN's experience with low- and medium-level radioactive waste treatment and conditioning over a period of almost 20 years. In addition to the construction of fixed waste processing facilities using more conventional technologies, SGN has been involved in application of the mobile system concept to the bituminization process in the United States, which led to the construction and commissioning of two transportable systems in collaboration with its American licensee US Ecology. It has also conducted large-scale R ampersand D on LLW/MLW concrete solidification, particularly for ion exchange resins. 5 figs

Advances in concrete materials for sewer systems affected by microbial induced concrete corrosion: A review.

Science.gov (United States)

Grengg, Cyrill; Mittermayr, Florian; Ukrainczyk, Neven; Koraimann, Günther; Kienesberger, Sabine; Dietzel, Martin

2018-05-01

Microbial induced concrete corrosion (MICC) is recognized as one of the main degradation mechanisms of subsurface infrastructure worldwide, raising the demand for sustainable construction materials in corrosive environments. This review aims to summarize the key research progress acquired during the last decade regarding the understanding of MICC reaction mechanisms and the development of durable materials from an interdisciplinary perspective. Special focus was laid on aspects governing concrete - micoorganisms interaction since being the central process steering biogenic acid corrosion. The insufficient knowledge regarding the latter is proposed as a central reason for insufficient progress in tailored material development for aggressive wastewater systems. To date no cement-based material exists, suitable to withstand the aggressive conditions related to MICC over its entire service life. Research is in particular needed on the impact of physiochemical material parameters on microbial community structure, growth characteristics and limitations within individual concrete speciation. Herein an interdisciplinary approach is presented by combining results from material sciences, microbiology, mineralogy and hydrochemistry to stimulate the development of novel and sustainable materials and mitigation strategies for MICC. For instance, the application of antibacteriostatic agents is introduced as an effective instrument to limit microbial growth on concrete surfaces in aggressive sewer environments. Additionally, geopolymer concretes are introduced as highly resistent in acid environments, thus representing a possible green alternative to conventional cement-based construction materials. Copyright © 2018 Elsevier Ltd. All rights reserved.

DURABILITY OF GREEN CONCRETE WITH TERNARY CEMENTITIOUS SYSTEM CONTAINING RECYCLED AGGREGATE CONCRETE AND TIRE RUBBER WASTES

Directory of Open Access Journals (Sweden)

MAJID MATOUQ ASSAS

2016-06-01

Full Text Available All over the world billions of tires are being discarded and buried representing a serious ecological threat. Up to now a small part is recycled and millions of tires are just stockpiled, landfilled or buried. This paper presents results about the properties and the durability of green concrete contains recycled concrete as a coarse aggregate with partial replacement of sand by tire rubber wastes for pavement use. Ternary cementious system, Silica fume, Fly ash and Cement Kiln Dust are used as partial replacement of cement by weight. Each one replaced 10% of cement weight to give a total replacement of 30%. The durability performance was assessed by means of water absorption, chloride ion permeability at 28 and 90 days, and resistance to sulphuric acid attack at 1, 7, 14 and 28 days. Also to the compression behaviors for the tested specimens at 7, 14, 28 and 90 days were detected. The results show the existence of ternary cementitious system, silica fly ash and Cement Kiln Dust minimizes the strength loss associated to the use of rubber waste. In this way, up to 10% rubber content and 30% ternary cementious system an adequate strength class value (30 MPa, as required for a wide range of common structural uses, can be reached both through natural aggregate concrete and recycled aggregate concrete. Results also show that, it is possible to use rubber waste up to 15% and still maintain a high resistance to acid attack. The mixes with 10%silica fume, 10% fly ash and 10% Cement Kiln Dust show a higher resistance to sulphuric acid attack than the reference mix independently of the rubber waste content. The mixes with rubber waste and ternary cementious system was a lower resistance to sulphuric acid attack than the reference mix.

Sorption of Cs, I, and actinides in concrete systems

International Nuclear Information System (INIS)

Allard, B.; Eliasson, L.; Andersson, K.

1984-09-01

Samples of seven different concretes were prepared (Standard Portland cement of two kinds; sulphate resistant, blast furnace slag, high alumina, fly ash, and silica cements) and the corresponding pore waters were analyzed. Batch-wise distribution studies were performed in the various concrete/pore water systems, as well as for three old concrete samples from a hydro power station dam (more than 60 years old), for the elements Cs, I, Th, U, Np, Pu, and Am at trace concentration levels. Generally the sorption of Cs was low, and somewhat higher for I. All the actinides, including U and Np in their hexa- and pentavalent states, respectively, were strongly sorbed on the cement phase. (Author)

SYSTEM FOR CONTROLLING ELECTRIC DRIVE OF ASPHALT CONCRETE MIXING PLANT

Directory of Open Access Journals (Sweden)

A. S. Surmak

2005-01-01

Full Text Available It is proposed to evaluate quality of asphalt concrete mixture through definition of current component variable of a drive motor and measurement of its derivative sign. In order to carry out final determination of mixture uniformity a transducer on the basis of a nuclear magnetic resonance is applied. Block diagram of the system is presented and algorithm of its operation is given in the paper. In addition to improvement of the finished product quality the application of the system makes it possible to reduce bitumen consumption used for production of asphalt concrete.

An Automated, Image Processing System for Concrete Evaluation

International Nuclear Information System (INIS)

Baumgart, C.W.; Cave, S.P.; Linder, K.E.

1998-01-01

Allied Signal Federal Manufacturing ampersand Technologies (FM ampersand T) was asked to perform a proof-of-concept study for the Missouri Highway and Transportation Department (MHTD), Research Division, in June 1997. The goal of this proof-of-concept study was to ascertain if automated scanning and imaging techniques might be applied effectively to the problem of concrete evaluation. In the current evaluation process, a concrete sample core is manually scanned under a microscope. Voids (or air spaces) within the concrete are then detected visually by a human operator by incrementing the sample under the cross-hairs of a microscope and by counting the number of ''pixels'' which fall within a void. Automation of the scanning and image analysis processes is desired to improve the speed of the scanning process, to improve evaluation consistency, and to reduce operator fatigue. An initial, proof-of-concept image analysis approach was successfully developed and demonstrated using acquired black and white imagery of concrete samples. In this paper, the automated scanning and image capture system currently under development will be described and the image processing approach developed for the proof-of-concept study will be demonstrated. A development update and plans for future enhancements are also presented

Concrete and criticality

International Nuclear Information System (INIS)

Carter, R.D.

1978-01-01

Concrete is a widely used structural material which occurs frequently in systems requiring criticality analyses. Ordinarily, we give little thought to what its actual composition is (as compared to reference compositions), yet in criticality safety, differences in composition can cause large changes in k-effective and it may not be easy to predict in which direction the change will occur. Concrete composition is quite variable with differences in the aggregate used in the concrete in various parts of the country providing relative large differences in k-effective. The water content of concrete can also strongly affect the reactivity of a system in which it acts as a reflector or is interspersed between fissile units. Because concrete is so common and is often (but not always) a better reflector than water, one must know the concrete compositions or be prepared to use a ''worst case'' composition. It may be a problem, however, to determine just what is the worst case. At the Hanford Plant, the aggregate normally used is basalt, which gives a composition very low in carbon as opposed to those areas (e.g., Oak Ridge) where the use of limestone aggregate will result in concrete with a high carbon content. The data presented show some of the effects found in situations using ''Hanford'' concrete, but similar effects might be found with other compositions. In some cases, the use of concrete may be incidental to the effects shown. While the numbers shown are those for actual systems, the primary intent is to alert the reader that these effects can occur. In applying this information, the analyst should use material specific to the systems being analyzed

Failure Modes in Concrete Repair Systems due to Ongoing Corrosion

Directory of Open Access Journals (Sweden)

Mladena Luković

2017-01-01

Full Text Available Corrosion of steel reinforcement is the main cause of deterioration in reinforced concrete structures. It can result in cracking and spalling of the concrete cover. After the damaged cover is repaired, reinforcement corrosion might continue and even accelerate. While the development of the corrosion cell is difficult to control, the damage can be possibly delayed and controlled by use of a suitable repair material. The lattice fracture model is used in this paper to investigate the performance of strain hardening cementitious composite (SHCC in concrete repair systems exposed to ongoing corrosion. Numerical results were verified by experimental tests when SHCC, nonreinforced material (repair mortar, and commercial repair mortar are used as repair materials. In experiments, reinforcement bars (surrounded by a repair material were exposed to accelerated corrosion tests. The influence of the substrate surface preparation, the type of repair material, the interface, and the substrate strength on the resulting damage and failure mode of repair systems are discussed. In general, SHCC repair enables distributed cracking with small crack widths, up to several times smaller compared to repair mortar. Furthermore, more warning signs prior to the final failure are present in the SHCC repair system.

Development of Vegetation-Pervious Concrete in Grid Beam System for Soil Slope Protection

Science.gov (United States)

Bao, Xiaohua; Liao, Wenyu; Dong, Zhijun; Wang, Shanyong; Tang, Waiching

2017-01-01

One of the most efficient and environmentally friendly methods for preventing a landslide on a slope is to vegetate it. Vegetation-pervious concretes have a promising potential for soil protection. In this study, the vegetation-pervious concrete with low alkalinity was developed and studied. Combined with a grid beam structure system, the stability and strength between the vegetation-pervious concrete and base soil are believed to be enhanced effectively. For improving plant adaptability, the alkalinity of concrete can be decreased innovatively by adding a self-designed admixture into the cement paste. The effects of the admixture content on alkalinity and compressive strength of the hardened pervious concrete were investigated using X-ray diffraction (XRD) and compression test, respectively. Meanwhile, the permeability of the vegetation-pervious concrete was studied as well. Through comparing with ordinary pervious concrete, the effect of low alkaline pervious concrete on vegetation growth was investigated in a small-scale field for ten weeks. The test results indicated that the alkalinity of the cement samples decreased with the increase of admixture content, and the vegetation grew successfully on previous concrete. By increasing the admixture content to approximately 3.6%, the compressive strength of pervious concrete was more than 25 MPa. PMID:28772454

Concrete structures

CERN Document Server

Setareh, Mehdi

2017-01-01

This revised, fully updated second edition covers the analysis, design, and construction of reinforced concrete structures from a real-world perspective. It examines different reinforced concrete elements such as slabs, beams, columns, foundations, basement and retaining walls and pre-stressed concrete incorporating the most up-to-date edition of the American Concrete Institute Code (ACI 318-14) requirements for the design of concrete structures. It includes a chapter on metric system in reinforced concrete design and construction. A new chapter on the design of formworks has been added which is of great value to students in the construction engineering programs along with practicing engineers and architects. This second edition also includes a new appendix with color images illustrating various concrete construction practices, and well-designed buildings. The ACI 318-14 constitutes the most extensive reorganization of the code in the past 40 years. References to the various sections of the ACI 318-14 are pro...

Sharing Experiences within AREVA D and D Project Portfolio: Four Illustrations - 13049

International Nuclear Information System (INIS)

Chabeuf, Jean-Michel; Varet, Thierry; AREVA Site Value Development Business Unit, La Hague Site

2013-01-01

Over the past ten years, AREVA has performed D and D operations on a wide range of nuclear sites, such as Marcoule and La Hague recycling plants, to Cadarache MOX fuel fabrication plant or Veurey and Annecy metallic Uranium machining plants. Each site is different from the other but some lessons can be shared through this D and D portfolio. In that respect, knowledge management is one of AREVA D and D Technical Department main missions. Four illustrations demonstrate the interest of knowledge share. Waste management is one of the key activities in D and D; It requires a specific characterization methodology, adapted logistics, and optimized waste channels, all of which have been developed over the years by AREVA teams on the site of Marcoule while they are rather new to La Hague, whose main activity remains fuel reprocessing despite the launch of UP2 400 D and D program. The transfer of know how has thus been organized over the past two years. Plasma cutting has been used extensively in Marcoule for years, while prohibited on the site of La Hague following questions raised about the risks associated wit Ruthenium sublimation. La Hague Technical Department has thus developed an experimental protocol to quantify and contain the Ruthenium risk, the result of which will then be applied to Marcoule where the Ruthenium issue has appeared in recent operations. Commissioning and operating fission products evaporators is a rather standard activity on UP2 800 and UP3, while the associated experience has been decreasing in Marcoule following final shutdown in 1998. When the French atomic Energy commission decided to build and operate a new evaporator to concentrate rinsing effluents prior to vitrification in 2009, AREVA La Hague operators were mobilized to test and commission the new equipment, and train local operators. Concrete scabbling is the final stage prior to the free release of a nuclear facility. In the context of Veurey and Annecy final cleanup and declassification

Sharing Experiences within AREVA D and D Project Portfolio: Four Illustrations - 13049

Energy Technology Data Exchange (ETDEWEB)

Chabeuf, Jean-Michel; Varet, Thierry [AREVA Site Value Development Business Unit, La Hague Site (France); AREVA Site Value Development Business Unit, La Hague Site

2013-07-01

Over the past ten years, AREVA has performed D and D operations on a wide range of nuclear sites, such as Marcoule and La Hague recycling plants, to Cadarache MOX fuel fabrication plant or Veurey and Annecy metallic Uranium machining plants. Each site is different from the other but some lessons can be shared through this D and D portfolio. In that respect, knowledge management is one of AREVA D and D Technical Department main missions. Four illustrations demonstrate the interest of knowledge share. Waste management is one of the key activities in D and D; It requires a specific characterization methodology, adapted logistics, and optimized waste channels, all of which have been developed over the years by AREVA teams on the site of Marcoule while they are rather new to La Hague, whose main activity remains fuel reprocessing despite the launch of UP2 400 D and D program. The transfer of know how has thus been organized over the past two years. Plasma cutting has been used extensively in Marcoule for years, while prohibited on the site of La Hague following questions raised about the risks associated wit Ruthenium sublimation. La Hague Technical Department has thus developed an experimental protocol to quantify and contain the Ruthenium risk, the result of which will then be applied to Marcoule where the Ruthenium issue has appeared in recent operations. Commissioning and operating fission products evaporators is a rather standard activity on UP2 800 and UP3, while the associated experience has been decreasing in Marcoule following final shutdown in 1998. When the French atomic Energy commission decided to build and operate a new evaporator to concentrate rinsing effluents prior to vitrification in 2009, AREVA La Hague operators were mobilized to test and commission the new equipment, and train local operators. Concrete scabbling is the final stage prior to the free release of a nuclear facility. In the context of Veurey and Annecy final cleanup and declassification

Hybrid FRP-concrete bridge deck system final report I : development and system performance validation.

Science.gov (United States)

2009-10-01

In this study, the concept of the hybrid FRP-concrete structural systems was applied to both bridge : superstructure and deck systems. Results from the both experimental and computational analysis for : both the hybrid bridge superstructure and deck ...

Concrete laying laboratory

International Nuclear Information System (INIS)

Bastlova, K.

1986-01-01

The task of the concrete laying laboratory established within a special department for quality control and assurance at the Dukovany nuclear power plant, is to check the composition of concrete mixes produced by the central concrete production plant on the site, and the shipment, laying and processing of concrete. The composition is given of special barite and serpentinite concretes designed for biological shields. The system of checks and of filing the results is briefly described. Esperience is summed up from the operation of the concrete laying laboratory, and conclusions are formulated which should be observed on similar large construction sites. They include the precise definition of the designer's requirements for the quality of concrete, the surface finish of concrete surfaces, the method of concreting specific structures around bushings, increased density reinforcements and various technological elements, and requirements for shipment to poorly accessible or remote places. As for the equipment of the laboratory, it should be completed with an instrument for the analysis of fresh concrete mixes, a large capacity drying kiln, etc. (Z.M.)

Waste Volume Reduction Using Surface Characterization and Decontamination By Laser Ablation

International Nuclear Information System (INIS)

Pellin, Michael J.; Savina, Michael R.; Reed, Claude B.; Zhiyue, Xu; Yong, Wang

2000-01-01

The U.S. Department of Energy's nuclear complex, a nation-wide system of facilities for research and production of nuclear materials and weapons, contains large amounts of radioactively contaminated concrete[1]. This material must be disposed of prior to the decommissioning of the various sites. Often the radioactive contaminants in concrete occupy only the surface and near-surface (∼3-6 mm deep) regions of the material. Since many of the structures such as walls and floors are 30 cm or more thick, it makes environmental and economic sense to try to remove and store only the thin contaminated layer rather than to treat the entire structure as waste. Current mechanical removal methods, known as scabbling, are slow and labor intensive, suffer from dust control problems, and expose workers to radiation fields. Improved removal methods are thus in demand[2-5]. Prior to decontamination, the surface must be characterized to determine the types and amounts of contaminants present i n order to decide on an appropriate cleaning strategy. Contamination occurs via exposure to air and water-borne radionuclides and by neutron activation. The radionuclides of greatest concern are (in order of abundance) [1]: 137Cs and 134Cs, 238U, 60Co, and 90Sr, followed by 3H, radioactive iodine, and a variety of Eu isotopes and transuranics. A system capable of on- line analysis is valuable since operators can determine the type of contaminants in real time and make more efficient use of costly sampling and characterization techniques. Likewise, the removed waste itself must be analyzed to insure that proper storage and monitoring techniques are used. The chemical speciation of radionuclides in concrete is largely unknown. Concrete is a complex material comprising many distinct chemical and physical phases on a variety of size scales[6-8]. Most studies of radionuclides in cements and concrete are for the most part restricted to phenomenological treatments of diffusion of ion s, particularly

Review of concrete properties for prestressed concrete pressure vesssels

International Nuclear Information System (INIS)

Nanstad, R.K.

1976-10-01

The desire for increasing power output along with safety requirements has resulted in consideration of the prestressed concrete pressure vessel (PCPV) for most current nuclear reactor systems, as well as for the very-high-temperature reactor for process heat and as primary pressure vessels for coal conversion systems. Results are presented of a literature review to ascertain current knowledge regarding plain concrete properties under conditions imposed by a mass concrete structure such as PCRV. The effects of high temperature on such properties as strength, elasticity, and creep are discussed, as well as changes in thermal properties, multiaxial behavior, and the mechanisms thought to be responsible for the observed behavior. In addition, the effects of radiation and moisture migration are discussed. It is concluded that testing results found in the technical literature show much disagreement as to the effects of temperature on concrete properties. The variations in concrete mixtures, curing and testing procedures, age at loading, and moisture conditions during exposure and testing are some of the reasons for such disagreement. Test results must be limited, in most cases, to the materials and conditions of a given test rather than applied to such a general class of materials such as concrete. It is also concluded that sustained exposure of normal concretes to current PCRV operating conditions will not result in any significant loss of properties. However, lack of knowledge regarding effects of temperatures exceeding 100 0 C (212 0 F), moisture migration, and multiaxial behavior precludes a statement advocating operation beyond current design limits. The report includes recommendations for future research on concrete for PCPVs

Development of System for Evaluating Concrete Strength Deterioration Due to Radiation and Resultant Heat

International Nuclear Information System (INIS)

Maruyama, I.; Kontani, O.; Ishizawa, A.; Takizawa, M.; Sato, O.

2012-01-01

Evaluation of the soundness of concrete exposed to irradiation has been studied within the framework of a project of the Nuclear and Industrial Safety Agency (NISA) 'Japan Ageing Management Program for System Safety'. This contribution presents the background to the existing evaluation processes, a review of the irradiation exposure effect on concrete and needs for irradiation testing. Based on results of this study, working assumptions for the development of an evaluation system are derived, and an overall picture of a numerical model as well as a framework for evaluating concrete soundness under irradiated conditions are proposed. (author)

Precast Concrete Beam-to-Column Connection System

OpenAIRE

ECT Team, Purdue

2007-01-01

Compared to conventional concrete constructions, precast concrete is a better option which is more cost-effective for production, transport, and erection when columns and beams can be fabricated independently. The BSF connection is a hidden beam and connection for gravity loads that eliminates the need for projecting column corbels. From a steel box cast into the concrete beam end, a sliding steel “knife” plate with a safety notch is cantilevered into a steel box that has been cast into the c...

Application of Interfacial Propagation and Kinking Crack Concept to ECC/Concrete Overlay Repair System

Directory of Open Access Journals (Sweden)

Yaw ChiaHwan

2014-01-01

Full Text Available Research on the application of ultraductile engineered cementitious composite (ECC as overlay in the repair of deteriorated concrete structures is performed in this paper. Also, interfacial crack kinking and trapping mechanism experimentally observed in ECC/concrete overlay repair system are described by comparison of toughness and energy release rate. The mechanism involves cycles of extension, kinking, and arrest of interfacial crack into the overlay. Experimental testing of overlay repair system reveals significant improvements in load carrying capacity and ductility over conventional concrete overlay. The commonly observed overlay system failure mode of delamination or spalling is eliminated when ECC is applied. These failure modes are suppressed when ECC is used as an ideal and durable candidate overlay repair material.

Historic Concrete : From Concrete Repair to Concrete Conservation

NARCIS (Netherlands)

Heinemann, H.A.

2013-01-01

Concrete like materials were already applied during the Roman Empire. After the decline of the Roman Empire, a wide scale application of concrete only reappeared in the 19th century. Here lies also the origin of modern (reinforced) concrete. Since then, both concrete application and composition have

The Significance of Coordination for Industrialised Building System (IBS) Precast Concrete in Construction Industry

OpenAIRE

Fitri Othman Mohd Khairul; Wan Muhammad Wan Mohd Nurdden; Abd Hadi Nurulhudaya; Azman Mohd Azrai

2017-01-01

IBS precast concrete is construction system which is meant to improve the conventional construction process. However IBS precast concrete projects are suffering from serious problems such as cost overrun, delays and less quality of the end product. The absence of coordination is perceived as the reason for this issue. The purpose of this paper is to review the significance of coordination for IBS precast concrete in the construction industry. It if found that the fragmentation which occurs in...

Classification of building systems for concrete 3D printing

OpenAIRE

DUBALLET , Romain; BAVEREL , Olivier; Dirrenberger , Justin

2017-01-01

In the present paper, a study is conducted on building systems associated with concrete extrusion-based additive manufacturing techniques. Specific parameters are highlighted - concerning scale, environment, support, and assembly strategies - and a classification method is introduced. The objective is to explicitly characterise construction systems based on such printing processes. A cartography of the different approaches and subsequent robotic complexity is proposed. The state of the art ga...

Solving decontaminable flooring problems

International Nuclear Information System (INIS)

Anon.

1989-01-01

Pennsylvania Power and Light wanted to cover deteriorating concrete in unit 2 of its Susquehanna BWR with a smooth, durable, decontaminable coating. Traditionally, floors in the plant had been coated with epoxy paint, but many of these floors suffered delamination, and failed in three to five years. Painting with epoxy would also interrupt operations for as much as three days while the floor dried, yet critical instruments in some areas had to be monitored at least once per shift. In addition, conventional floor surface preparation produced dust and vibration around sensitive equipment. The solution was a dustless scabbling system for surface preparation, followed by the installation of a high-strength acrylic industrial floor known as Silakal. The work was carried out by Pentek. Silikal bonds to the underlying concrete, so that delamination of the floor will not occur even under severe traffic conditions. Another advantage of this type of flooring is that it cures in one hour, so floor resurfacing has only minimal impact on plant operations. (author)

Retrofitting the AutoBayes Program Synthesis System with Concrete Syntax

Science.gov (United States)

Fischer, Bernd; Visser, Eelco

2004-01-01

AutoBayes is a fully automatic, schema-based program synthesis system for statistical data analysis applications. Its core component is a schema library. i.e., a collection of generic code templates with associated applicability constraints which are instantiated in a problem-specific way during synthesis. Currently, AutoBayes is implemented in Prolog; the schemas thus use abstract syntax (i.e., Prolog terms) to formulate the templates. However, the conceptual distance between this abstract representation and the concrete syntax of the generated programs makes the schemas hard to create and maintain. In this paper we describe how AutoBayes is retrofitted with concrete syntax. We show how it is integrated into Prolog and describe how the seamless interaction of concrete syntax fragments with AutoBayes's remaining legacy meta-programming kernel based on abstract syntax is achieved. We apply the approach to gradually mitigate individual schemas without forcing a disruptive migration of the entire system to a different First experiences show that a smooth migration can be achieved. Moreover, it can result in a considerable reduction of the code size and improved readability of the code. In particular, abstracting out fresh-variable generation and second-order term construction allows the formulation of larger continuous fragments.

Massive Niagara Falls power generation project uses unique concrete locking system

Energy Technology Data Exchange (ETDEWEB)

Polski, A. [Con Cast Pipe, Niagara Falls, ON (Canada)

2006-09-15

A 512 metre long accelerating wall and a 360 metre-long approach wall in the Niagara River are being built using a novel locking system to withstand the forces of nature. The walls have been designed to direct continuous flow to a new diversion tunnel below the City of Niagara Falls, Ontario. The walls are made of a single row of pre-cast concrete boxes that lock together in a special configuration to prevent movement from extreme load combinations in the Niagara River. The system was designed as part of a larger project to increase the power generating capabilities of the Sir Adam Beck 2 power generation station. Water channelled into the new tunnel will provide an estimated additional 1.6 terawatt-hours of renewable electricity annually and expand capacity at the station by about 15 per cent. The pre-cast reinforced concrete box design was chosen for the walls as it allowed fast and simple assembly of the structures. The basic structural system for each box is 4 vertical panels that form an open rectangular wall. The boxes are filled with clean rock fragments that are uniformly graded. Once the boxes are installed, cast-in-place concrete slabs will be poured to a depth of approximately 600 mm on top of the wall to cap the entire structure. The value of the design-build contract for the Niagara project is nearly $600 million out of an estimated $985 million budget. Commonly used for the design of culverts, the concrete box technology holds promise for applications including the stabilization of shorelines and the construction of small dams. 3 figs.

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.

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

International Nuclear Information System (INIS)

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

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. (paper)

On-site concrete cask storage system for spent nuclear fuel

International Nuclear Information System (INIS)

Craig, P.A.; Haelsig, R.T.; Kent, J.D.; Schmoker, D.S.

1989-01-01

A method is described of storing spent nuclear fuel assemblies including the steps of: transferring the fuel assemblies from a spent-fuel pool to a moveable concrete storage cask located outside the spent-fuel pool; maintaining a barrier between the fuel and the concrete in the cask to prevent contamination of the concrete by the fuel; maintaining the concrete storage cask containing the spent-fuel on site at the reactor complex for some predetermined period; transferring the fuel assemblies from the concrete storage cask to a shipping container; and, recycling the concrete storage cask

Improvements Realized on the NiThrow{sup TM} Solution - 13075

Energy Technology Data Exchange (ETDEWEB)

Moggia, F.; Objois, L.; Damerval, F. [AREVA - Clean-Up BU - 1, route de la Noue - 91196 Gif-sur-Yvette (France); Toulemonde, V. [AREVA - R and D Corporate - 1, place Jean Miller - 92084 - Paris La Defense (France); Varet, T. [AREVA - D and D BU - 1, place Jean Miller - Paris La Defense (France); Guillot, S. [AREVA Federal Services LLC - 2101 Horn Rapids Road Richland, WA 99354-5102 (United States); Richard, F. [Air Liquide - Research Center - 13, rue d' Epluches - 95310 St Ouen L' Aumone (France)

2013-07-01

Two years ago we presented the first results obtained with the highly pressurized liquid nitrogen technology (HPLN) in case of cutting, surface decontamination and concrete scabbling applications. These results, carried out in non active conditions, were really promising in term of efficiency and productivity and highlighted how this technology was interesting for D and D business (e.g. cut of depth up to 30 mm for concrete scabbling application; productivity of 4 cm.min{sup -1} in case of the cut of a 50 mm thick stainless steel ingot..). We also found some real issues which were not compatible with its use in a radioactive environment. Indeed, the reliability of some parts of the system was not efficient enough (e.g. lancing tool, intensifiers...) to run the HPLN technology in good conditions. More than two years, after a complete study of the whole system, and after the compilation of all the required troubleshooting, AREVA with its partner Air Liquide, decided to start a complete R and D work in order to improve this cryogenic technology. Our engineers started with the lancing tool and designed a new one lighter and more reliable than the original one. After that, they improved the reliability of the pressurization unit (skid) by changing seals and other parts. As mentioned above, the goal of this work was to implement this technology in a nuclear environment the best way. We also focused our efforts on the insulation of the high pressure hoses (with a maximal distance, between the 'skid - Heat exchanger' module and the lancing tool, of about 110 meters), and on the development of a quite efficient vacuum system comprising dust collection units (we can guarantee an efficiency of our system higher than 95%). Finally, the last step of our development was devoted to the design and the manufacturing of a dedicated carrier enabling the technology to move in all directions (X,Y and Z) and to reach all the positions (wall, ground, ceiling and for sure all

Improvements Realized on the NiThrowTM Solution - 13075

International Nuclear Information System (INIS)

Moggia, F.; Objois, L.; Damerval, F.; Toulemonde, V.; Varet, T.; Guillot, S.; Richard, F.

2013-01-01

Two years ago we presented the first results obtained with the highly pressurized liquid nitrogen technology (HPLN) in case of cutting, surface decontamination and concrete scabbling applications. These results, carried out in non active conditions, were really promising in term of efficiency and productivity and highlighted how this technology was interesting for D and D business (e.g. cut of depth up to 30 mm for concrete scabbling application; productivity of 4 cm.min -1 in case of the cut of a 50 mm thick stainless steel ingot..). We also found some real issues which were not compatible with its use in a radioactive environment. Indeed, the reliability of some parts of the system was not efficient enough (e.g. lancing tool, intensifiers...) to run the HPLN technology in good conditions. More than two years, after a complete study of the whole system, and after the compilation of all the required troubleshooting, AREVA with its partner Air Liquide, decided to start a complete R and D work in order to improve this cryogenic technology. Our engineers started with the lancing tool and designed a new one lighter and more reliable than the original one. After that, they improved the reliability of the pressurization unit (skid) by changing seals and other parts. As mentioned above, the goal of this work was to implement this technology in a nuclear environment the best way. We also focused our efforts on the insulation of the high pressure hoses (with a maximal distance, between the 'skid - Heat exchanger' module and the lancing tool, of about 110 meters), and on the development of a quite efficient vacuum system comprising dust collection units (we can guarantee an efficiency of our system higher than 95%). Finally, the last step of our development was devoted to the design and the manufacturing of a dedicated carrier enabling the technology to move in all directions (X,Y and Z) and to reach all the positions (wall, ground, ceiling and for sure all the singularities

Progress of admixtures and quality of concrete. 2. ; Approaches to ultra-high-strength concrete. Konwa zairyo no shinpo to concrete no hinshitsu. 2. ; Chokokyodo concrete eno approach

Energy Technology Data Exchange (ETDEWEB)

Kawai, T. (Shimizu Construction Co. Ltd., Tokyo (Japan)); Abe, M. (Building Research Institute, Tsukuba (Japan))

1994-02-15

Ultra-high-strength concrete of 600 kgf/cm[sup 2] or more is reviewed. MDF (macro defect free) cement, spheroidal cement and mechanically stabilized cement have been developed for ultra-high-strength concrete, however, in general, DSP (densified system containing homogeneously arranged ultra-fine particles) technique is now usual in which a water-cement ratio is reduced by use of advanced air entraining and water reducing agents and cured concrete is densified by use of ultra-fine particles as admixture. Four kinds of substances such as naphthalene system and polycarboxylic acid system are used as air entraining and water reducing agents, and silica fume is used as ultra-fine particle admixture which can be effectively replaced with blast furnace slag or fly ash. Various use examples of ultra-high-strength concrete such as an ocean platform are found in the world, however, only some examples such as a PC truss bridge and the main tower of a PC cable stayed bridge in Japan. 22 refs., 10 figs., 2 tabs.

Nondestructive Evaluation of Concrete Bridge Decks with Automated Acoustic Scanning System and Ground Penetrating Radar.

Science.gov (United States)

Sun, Hongbin; Pashoutani, Sepehr; Zhu, Jinying

2018-06-16

Delamanintions and reinforcement corrosion are two common problems in concrete bridge decks. No single nondestructive testing method (NDT) is able to provide comprehensive characterization of these defects. In this work, two NDT methods, acoustic scanning and Ground Penetrating Radar (GPR), were used to image a straight concrete bridge deck and a curved intersection ramp bridge. An acoustic scanning system has been developed for rapid delamination mapping. The system consists of metal-ball excitation sources, air-coupled sensors, and a GPS positioning system. The acoustic scanning results are presented as a two-dimensional image that is based on the energy map in the frequency range of 0.5⁻5 kHz. The GPR scanning results are expressed as the GPR signal attenuation map to characterize concrete deterioration and reinforcement corrosion. Signal processing algorithms for both methods are discussed. Delamination maps from the acoustic scanning are compared with deterioration maps from the GPR scanning on both bridges. The results demonstrate that combining the acoustic and GPR scanning results will provide a complementary and comprehensive evaluation of concrete bridge decks.

Numerical modelling of the reinforced concrete influence on a combined system of tunnel support

Directory of Open Access Journals (Sweden)

Grujić Bojana

2017-12-01

Full Text Available The paper presents the experimental, laboratory determined rheological-dynamic analysis of the properties of fiber reinforced concrete, which was then utilized to show nonlinear analysis of combined system of tunnel support structure. According to the performed experiments and calculations, different processes of destructive behavior of tunnel lining were simulated in combination with elastic and elastic-plastic behavior of materials taking into account the tunnel loading, the interaction between the fiber reinforced concrete and soil, as well as the interaction between the fiber reinforced concrete and the inner lining of the tunnel.

Numerical modelling of the reinforced concrete influence on a combined system of tunnel support

Science.gov (United States)

Grujić, Bojana; Jokanović, Igor; Grujić, Žarko; Zeljić, Dragana

2017-12-01

The paper presents the experimental, laboratory determined rheological-dynamic analysis of the properties of fiber reinforced concrete, which was then utilized to show nonlinear analysis of combined system of tunnel support structure. According to the performed experiments and calculations, different processes of destructive behavior of tunnel lining were simulated in combination with elastic and elastic-plastic behavior of materials taking into account the tunnel loading, the interaction between the fiber reinforced concrete and soil, as well as the interaction between the fiber reinforced concrete and the inner lining of the tunnel.

An Expert System for Concrete Bridge Management

DEFF Research Database (Denmark)

Brito, J. de; Branco, F. A.; Thoft-Christensen, Palle

1997-01-01

The importance of bridge repair versus new bridge construction has risen in recent decades due to high deterioration rates that have been observed in these structures. Budgets both for building new bridges and keeping the existing ones are always limited. To help rational decision-making, bridge...... management systems are presently being implemented by bridge authorities in several countries. The prototype of an expert system for concrete bridge management is presented in this paper, with its functionality relying on two modules. The inspection module relies on a periodic acquisition of field...... information complemented by a knowledge-based interactive system, BRIDGE-1. To optimize management strategies at the headquarters, the BRIDGE-2 module was implemented, including three submodules: inspection strategy, maintenance and repair....

Testing of plain and fibrous concrete single cavity prestressed concrete reactor vessel models

International Nuclear Information System (INIS)

Oland, C.B.

1985-01-01

Two single-cavity prestressed concrete reactor vessel (PCRV) models were fabricated and tested to failure to demonstrate the structural response and ultimate pressure capacity of models cast from high-strength concretes. Concretes with design compressive strengths in excess of 70 MPa (10,000 psi) were developed for this investigation. One model was cast from plain concrete and failed in shear at the head region. The second model was cast from fiber reinforced concrete and failed by rupturing the circumferential prestressing at the sidewall of the structure. The tests also demonstrated the capabilities of the liner system to maintain a leak-tight pressure boundary. 3 refs., 4 figs

The calculation of phase equilibria of oxide core-concrete systems

International Nuclear Information System (INIS)

Ball, R.G.J.; Mignanelli, M.A.; Barry, T.I.; Gisby, J.A.

1993-01-01

Thermodynamic models have been developed to describe the phase equilibria of oxide solutions appropriate for the understanding of the chemical interactions between nuclear reactor core debris and concrete. For this purpose, the Gibbs energy of the liquid phase is described by the inclusion of associate species and nonideal interactions between the components and associate species. Assessments of the thermodynamic and phase equilibrium data for the subsystems of the CaO-Al 2 O 3 -SiO 2 -UO 2 -ZrO 2 system have been used to obtain a thermodynamic description of the crystalline and liquid phases in good agreement with published data. The data for the subsystems have then been combined, using well established principles, to predict the phase relationships in the ternary and quaternary sytsems and in the overall quinary system. The results show that he overall system cannot properly be treated as a pseudo-ideal liquid and solid solution, as used in some computer codes which attempt to model the physics and chemistry of core-concrete interactions. The limitations of the current model are discussed. (orig.)

Chloride Penetration through Cracks in High-Performance Concrete and Surface Treatment System for Crack Healing

Directory of Open Access Journals (Sweden)

In-Seok Yoon

2012-01-01

Full Text Available For enhancing the service life of concrete structures, it is very important to minimize crack at surface. Even if these cracks are very small, the problem is to which extend these cracks may jeopardize the durability of these decks. It was proposed that crack depth corresponding with critical crack width from the surface is a crucial factor in view of durability design of concrete structures. It was necessary to deal with chloride penetration through microcracks characterized with the mixing features of concrete. This study is devoted to examine the effect of high strength concrete and reinforcement of steel fiber on chloride penetration through cracks. High strength concrete is regarded as an excellent barrier to resist chloride penetration. However, durability performance of cracked high strength concrete was reduced seriously up to that of ordinary cracked concrete. Steel fiber reinforcement is effective to reduce chloride penetration through cracks because steel fiber reinforcement can lead to reduce crack depth significantly. Meanwhile, surface treatment systems are put on the surface of the concrete in order to seal the concrete. The key-issue is to which extend a sealing is able to ensure that chloride-induced corrosion can be prevented. As a result, penetrant cannot cure cracks, however, coating and combined treatment can prevent chloride from flowing in concrete with maximum crack width of 0.06 mm and 0.08 mm, respectively.

Evaluation of structural systems in precast concrete buildings by ...

African Journals Online (AJOL)

In general, the precast concrete is the type of concrete that constructing, casting and curing in the standard factory conditions with high quality and then it will be transported with proper equipments and then it will be installed in the final position. In fact, the precast concrete buildings are the combined of several types of ...

Impact of hydrated cement paste quality and entrained air-void system on the durability of concrete.

Science.gov (United States)

2011-06-30

This study is designed to examine whether traditional limits used to describe the air-void system still : apply to concrete prepared with new admixtures and materials. For this research, the concrete mixtures : prepared were characterized with tradit...

Diffusion of radionuclides in concrete/bentonite systems

International Nuclear Information System (INIS)

Albinsson, Y.; Boerjesson, S.; Andersson, K.; Allard, B.

1993-02-01

In a repository for nuclear waste, different construction materials will be used. Two important materials among these are concrete and bentonite clay. These will act as mechanical barriers, preventing convective water flow and also retard transport due to diffusion of dissolved radionuclides by a combination of mechanical constraints and chemical interactions with the solid. An important issue is the possible change of the initial sodium bentonite into the calcium form due to ion exchange with calcium from the cement. The initial leaching of the concrete has been studied using radioactive spiked concrete in contact with compacted bentonite. The diffusion of Cs, Am and Pu into 5 different types of concrete in contact with porewater have been measured. The measured diffusivity for Cs agrees reasonable well with data found in literature. For Am and Pu no movement could be measured (less than 0.2 mm) even though the contact times were extremely long (2.5 y and 5 y, respectively). This report gives also a summary of the previously published results about sorption and diffusion of radionuclides in cement performed in Prav/KBS/SKB projects 1980-1990. 25 refs

Phase 2 microwave concrete decontamination results

International Nuclear Information System (INIS)

White, T.L.; Foster, D. Jr.; Wilson, C.T.; Schaich, C.R.

1995-01-01

The authors report on the results of the second phase of a four-phase program at Oak Ridge National Laboratory to develop a system to decontaminate concrete using microwave energy. The microwave energy is directed at the concrete surface through the use of an optimized wave guide antenna, or applicator, and this energy rapidly heats the free water present in the interstitial spaces of the concrete matrix. The resulting steam pressure causes the surface to burst in much the same way popcorn pops in a home microwave oven. Each steam explosion removes several square centimeters of concrete surface that are collected by a highly integrated wave guide and vacuum system. The authors call this process the microwave concrete decontamination, or MCD, process. In the first phase of the program the principle of microwaves concrete removal concrete surfaces was demonstrated. In these experiments, concrete slabs were placed on a translator and moved beneath a stationary microwave system. The second phase demonstrated the ability to mobilize the technology to remove the surfaces from concrete floors. Area and volume concrete removal rates of 10.4 cm 2 /s and 4.9 cm 3 /S, respectively, at 18 GHz were demonstrated. These rates are more than double those obtained in Phase 1 of the program. Deeper contamination can be removed by using a longer residence time under the applicator to create multiple explosions in the same area or by taking multiple passes over previously removed areas. Both techniques have been successfully demonstrated. Small test sections of painted and oil-soaked concrete have also been removed in a single pass. Concrete with embedded metal anchors on the surface has also been removed, although with some increased variability of removal depth. Microwave leakage should not pose any operational hazard to personnel, since the observed leakage was much less than the regulatory standard

The Significance of Coordination for Industrialised Building System (IBS Precast Concrete in Construction Industry

Directory of Open Access Journals (Sweden)

Fitri Othman Mohd Khairul

2017-01-01

Full Text Available IBS precast concrete is construction system which is meant to improve the conventional construction process. However IBS precast concrete projects are suffering from serious problems such as cost overrun, delays and less quality of the end product. The absence of coordination is perceived as the reason for this issue. The purpose of this paper is to review the significance of coordination for IBS precast concrete in the construction industry. It if found that the fragmentation which occurs in the construction industry requires continuity of coordination due to the construction activities are intertwined in nature. Coordination is designated to assist stakeholders in completing and complementing each other with the paramount focus of achieving the objective. Proper coordination is required in delivering the desired construction product at the ideal time, cost and quality. As for the findings, the significance of coordination for IBS precast concrete can be seen through the precast concrete construction phases which consist of planning; design; manufacturing; transportation and installation/construction. These phases are meant to complement construction process with the purpose to reduce issues of fragmentation and enhance IBS precast concrete project delivery.

concrete5 cookbook

CERN Document Server

Strack, David

2013-01-01

The Cookbook-style recipes allow you to go both directly to your topic of interest or follow topics throughout a chapter to gain in-depth knowledge. This practical Cookbook will cater to the needs of both intermediate and advanced concrete5 developers.This book is geared towards intermediate to advanced PHP developers who would like to learn more about the concrete5 content management system. Developers already familiar with concrete5 will learn new time-saving tricks and will find the book to be a great reference tool.

Thermal protection system for the concrete core support floor at Fort St. Vrain

International Nuclear Information System (INIS)

Jones, H.; Hedgecock, P.D.

1976-01-01

A unique feature of the Fort St. Vrain HTGR is its steel jacketed concrete core support floor. The construction of this floor generally resembles that of the prestressed concrete reactor vessel, but its location immediately below the core hot gas outlets generates some particularly severe thermal protection requirements. A thermal barrier is used over the entire outer surface of the floor and in the twelve hot gas ducts which convey the primary coolant through the floor to the steam generators. A cooling water system of square tubes welded to the inside of the steel jacket is used to remove that heat which does pass through the thermal barrier and to maintain the concrete at acceptable temperatures. The design approach to the floor itself and to the thermal barriers and cooling system will be described, but the main emphasis of the paper will be on the total experience gained during construction and pre-operational testing. A particular problem experienced during construction was leakage from some cooling tubes, after their embedment in concrete. The solution to that problem was to develop a method for injecting catalyzed epoxy into the leaking tube. This method, which has general usefulness for in-service repairs, will be described. (author)

DEVELOPMENT OF NON-DESTRUCTIVE MONITORING SYSTEM FOR CHLORIDE PENETRATION INTO REINFORCED CONCRETE STRUCTURES

Directory of Open Access Journals (Sweden)

Antoni Antoni

2006-01-01

Full Text Available Reinforced concrete structures in marine environment are subjected to chloride penetration, which significantly degrades the structural performance due to the occurrence of corrosion in the steel reinforcement. The performance degradation of the structures would reduce the intended service life and caused higher maintenance and repair cost. Therefore, system to monitor chloride penetration into reinforced concrete before the starting corrosion of reinforcement is indispensable. An embedded probe system to detect chloride penetration into concrete was developed in Japan. This probe consists of a cementitious material body and some number of wires as sensors, which are set in the shallow ditches around the probe body. The system detect the chloride penetration by monitoring the initiation time of wire corrosion, it also has the advantages of continuous monitoring and early warning on the onset of corrosion in the reinforcement. However, the probe had not yet had high sensitivity for detecting critical chloride content in concrete. Therefore to increase its sensitivity, four types of improvements, namely partial coating of the wires, waterproofing on the probe body, filling the ditches with porous material and supplying small current on the wires were evaluated in this study. From the experimental result, it was observed that supplying small current and partial coating of the wires could improve the sensitivity of the probe significantly, while waterproofing treatment on the probe body and filling the ditches did not have significant contribution.

Development of heat resistant concrete and its application to concrete casks. Improvement of neutron shielding performance of concrete in high temperature environment

International Nuclear Information System (INIS)

Owaki, Eiji; Hata, Akihito; Sugihara, Yutaka; Shimojo, Jun; Taniuchi, Hiroaki; Mantani, Kenichi

2003-01-01

Heat resistant concrete with hydrogen, which is able to shield neutron at more than 100degC, was developed. Using this new type concrete, a safety concrete cask having the same concept of metal casks was designed and produced. The new type cask omitted the inhalation and exhaust vent of the conventional type concrete casks. The new concrete consists of Portland cement added calcium hydroxide, iron powder and iron fiber. It showed 2.17 g/cm 3 density, 10.8 mass% water content, 1.4 W/(m·K) thermal conductivity at 150degC. Increasing of heat resistance made possible to produce the perfect sealing type structure, which had high shielding performance of radiation no consideration for streaming of radiation. Moreover, a monitor of sealing can be set. General view of concrete casks, outer view of 1/3 scaled model, cask storage system in the world, properties of new developed heat resistant concrete, results of shielding calculation are contained. (S.Y.)

Dynamic Heat Storage and Cooling Capacity of a Concrete Deck with PCM and Thermally Activated Building System

DEFF Research Database (Denmark)

Pomianowski, Michal Zbigniew; Heiselberg, Per; Jensen, Rasmus Lund

2012-01-01

This paper presents a heat storage and cooling concept that utilizes a phase change material (PCM) and a thermally activated building system (TABS) implemented in a hollow core concrete deck. Numerical calculations of the dynamic heat storage capacity of the hollow core concrete deck element...... in the article highlight the potential of using TABS and PCM in a prefabricated concrete deck element....

Concrete pavement mixture design and analysis (MDA) : assessment of air void system requirements for durable concrete.

Science.gov (United States)

2012-06-01

Concrete will suffer frost damage when saturated and subjected to freezing temperatures. Frost-durable concrete can be produced if a : specialized surfactant, also known as an air-entraining admixture (AEA), is added during mixing to stabilize micros...

Recycled Concrete as Aggregate for Structural Concrete Production

Directory of Open Access Journals (Sweden)

Mirjana Malešev

2010-04-01

Full Text Available A comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement ratios of natural with recycled coarse aggregate is presented in the paper. Recycled aggregate was made by crushing the waste concrete of laboratory test cubes and precast concrete columns. Three types of concrete mixtures were tested: concrete made entirely with natural aggregate (NAC as a control concrete and two types of concrete made with natural fine and recycled coarse aggregate (50% and 100% replacement of coarse recycled aggregate. Ninety-nine specimens were made for the testing of the basic properties of hardened concrete. Load testing of reinforced concrete beams made of the investigated concrete types is also presented in the paper. Regardless of the replacement ratio, recycled aggregate concrete (RAC had a satisfactory performance, which did not differ significantly from the performance of control concrete in this experimental research. However, for this to be fulfilled, it is necessary to use quality recycled concrete coarse aggregate and to follow the specific rules for design and production of this new concrete type.

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,…

Usage of Crushed Concrete Fines in Decorative Concrete

Science.gov (United States)

Pilipenko, Anton; Bazhenova, Sofia

2017-10-01

The article is devoted to the questions of usage of crushed concrete fines from concrete scrap for the production of high-quality decorative composite materials based on mixed binder. The main problem in the application of crushed concrete in the manufacture of decorative concrete products is extremely low decorative properties of crushed concrete fines itself, as well as concrete products based on them. However, crushed concrete fines could have a positive impact on the structure of the concrete matrix and could improve the environmental and economic characteristics of the concrete products. Dust fraction of crushed concrete fines contains non-hydrated cement grains, which can be opened in screening process due to the low strength of the contact zone between the hydrated and non-hydrated cement. In addition, the screening process could increase activity of the crushed concrete fines, so it can be used as a fine aggregate and filler for concrete mixes. Previous studies have shown that the effect of the usage of the crushed concrete fines is small and does not allow to obtain concrete products with high strength. However, it is possible to improve the efficiency of the crushed concrete fines as a filler due to the complex of measures prior to mixing. Such measures may include a preliminary mechanochemical activation of the binder (cement binder, iron oxide pigment, silica fume and crushed concrete fines), as well as the usage of polycarboxylate superplasticizers. The development of specific surface area of activated crushed concrete fines ensures strong adhesion between grains of binder and filler during the formation of cement stone matrix. The particle size distribution of the crushed concrete fines could achieve the densest structure of cement stone matrix and improve its resistance to environmental effects. The authors examined the mechanisms of structure of concrete products with crushed concrete fines as a filler. The results of studies of the properties of

Biodecontamination of concrete

International Nuclear Information System (INIS)

Hamilton, M.A.; Rogers, R.D.; Benson, J.

1996-01-01

A novel technology for biologically decontaminating concrete is being jointly developed by scientists at the Idaho National Engineering Laboratory (INEL) and British Nuclear Fuels plc (BNFL). The technology exploits a naturally occurring phenomenon referred to as microbially influenced degradation (MID) in which bacteria produce acids that dissolve the cement matrix of concrete. Most radionuclide contamination of concrete is fixed in the outer few mm of the concrete surface. By capturing and controlling this natural process, a biological method of removing the surface of concrete to depths up to several mm is being developed. Three types of bacteria are known to be important in MID of concrete: nitrifying bacteria that produce nitric acid, sulfur oxidizing bacteria that produce sulfuric acid, and certain heterotrophic bacteria that produce organic acids. An investigation of natural environments demonstrated with scanning electron microscopy the presence of bacteria on concrete surfaces of a variety of structures, such as bridges and dams, where corrosion is evident. Enumeration of sulfur oxidizing and nitrifying bacteria revealed their presence and activity on structures to varying degrees in different environments. Under ideal conditions, Thiobacillus thiooxidans, a sulfur oxidizing bacteria, attached to and colonized the surface of concrete specimens. Over 1mm depth of material from a 10 cm x 10 cm square surface was removed in 68 days in the Thiobacillus treated specimen compared to a sterile control. Laboratory and field demonstrations are currently being conducted using experimental chambers designed to be mounted directly to concrete surfaces where radionuclide contamination exists. Data is being obtained in order to determine actual rates of surface removal and limitations to the system. This information will be used to develop a full scale decontamination technology

Synthesis of concrete bridge piles prestressed with CFRP systems.

Science.gov (United States)

2017-06-01

The Texas Department of Transportation frequently constructs prestressed concrete piles for use in bridge : foundations. Such prestressed concrete piles are typically built with steel strands that are highly susceptible to : environmental degradation...

Prestressed-concrete pressure vessels and their applicability to advanced-energy-system concepts

International Nuclear Information System (INIS)

Naus, D.J.

1983-01-01

Prestressed concrete pressure vessels (PCPVs) are, in essence, spaced steel structures since their strength is derived from a multitude of steel elements made up of deformed reinforcing bars and prestressing tendons which are present in sufficient quantities to carry tension loads imposed on the vessel. Other major components of a PCPV include the concrete, liner and cooling system, and insulation. PCPVs exhibit a number of advantages which make them ideally suited for application to advanced energy concepts: fabricability in virtually any size and shape using available technology, improved safety, reduced capital costs, and a history of proven performance. PCPVs have many applications to both nuclear- and non-nuclear-based energy systems concepts. Several of these concepts will be discussed as well as the research and development activities conducted at ORNL in support of PCPV development

A modelling study of drying shrinkage damage in concrete repair systems

NARCIS (Netherlands)

Lukovic, M.; Savija, B.; Schlangen, E.; Ye, G.; van Breugel, K.

2014-01-01

Differential shrinkage between repair material and concrete substrate is considered to be the main cause of premature failure of repair systems (Martinola, Sadouki et al. 2001, Beushausen and Alexander 2007). Magnitude of induced stresses depends on many factors, for example the amount of restraint,

Recycled Concrete as Aggregate for Structural Concrete Production

OpenAIRE

Mirjana Malešev; Vlastimir Radonjanin; Snežana Marinković

2010-01-01

A comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement ratios of natural with recycled coarse aggregate is presented in the paper. Recycled aggregate was made by crushing the waste concrete of laboratory test cubes and precast concrete columns. Three types of concrete mixtures were tested: concrete made entirely with natural aggregate (NAC) as a control concrete and two types of concrete made with natural fine and recycle...

The Future Concrete: Self-Compacting Concrete

OpenAIRE

Iureş, Liana; Bob, Corneliu

2010-01-01

The paper presents the characteristics of the self-compacting concretes, their advantages and disadvantages when they are used in buildings. Due to its properties and composition, the self-compacting concrete is described here as being one of the future friendly enviromental material for buildings. Tests concerning to obtaining a self-compacting concrete, together with the specific fresh concrete properties tests, are described.

Study on heat removal capability concrete cask system with horizontal orientation

International Nuclear Information System (INIS)

Nabemoto, Toyonobu; Sakai, Mikio; Fujiwara, Hiroaki; Sakaya, Tadatsugu

2002-01-01

In Japan, nuclear fuel cycle, has been promoted, so the recycle fuels formed at nuclear power stations are planned to be processed at reprocessing facilities in future. However, as forming quantities of the recycle fuels are more than reprocessing quantities of the facilities, it is needed to practice a facility (interim storage facility (ISF)) to temporarily store them among the recycle fuels will be reprocessed. The Ishikawajima-Harima Heavy Industries, Co., Ltd. has investigated on vault system and concrete cask system for dry storage system with excellent economical efficiency among various systems on ISFs. As the latter method has a number of actual results in U.S.A., its practice is progressed after some improvements suitable for Japan. When progressing this practice on the latter method on fiscal year 1999, at first, a concrete cask with actual size was experimentally produced, to confirm its productivity. On fiscal year 2000, aiming to establish heat removal evaluation at storage, a thermal load test simulated at the storage was carried out by using this trial product. Here was reported results obtained at a test simulated at repacking carried out on fiscal year 2001. (G.K.)

DECONTAMINATION TECHNOLOGIES FOR FACILITY REUSE

International Nuclear Information System (INIS)

Bossart, Steven J.; Blair, Danielle M.

2003-01-01

As nuclear research and production facilities across the U.S. Department of Energy (DOE) nuclear weapons complex are slated for deactivation and decommissioning (D and D), there is a need to decontaminate some facilities for reuse for another mission or continued use for the same mission. Improved technologies available in the commercial sector and tested by the DOE can help solve the DOE's decontamination problems. Decontamination technologies include mechanical methods, such as shaving, scabbling, and blasting; application of chemicals; biological methods; and electrochemical techniques. Materials to be decontaminated are primarily concrete or metal. Concrete materials include walls, floors, ceilings, bio-shields, and fuel pools. Metallic materials include structural steel, valves, pipes, gloveboxes, reactors, and other equipment. Porous materials such as concrete can be contaminated throughout their structure, although contamination in concrete normally resides in the top quarter-inch below the surface. Metals are normally only contaminated on the surface. Contamination includes a variety of alpha, beta, and gamma-emitting radionuclides and can sometimes include heavy metals and organic contamination regulated by the Resource Conservation and Recovery Act (RCRA). This paper describes several advanced mechanical, chemical, and other methods to decontaminate structures, equipment, and materials

The Future Concrete: Self-Compacting Concrete

Directory of Open Access Journals (Sweden)

Liana Iureş

2010-01-01

Full Text Available The paper presents the characteristics of the self-compacting concretes, their advantages and disadvantages when they are used in buildings. Due to its properties and composition, the self-compacting concrete is described here as being one of the future friendly enviromental material for buildings. Tests concerning to obtaining a self-compacting concrete, together with the specific fresh concrete properties tests, are described.

76 FR 34890 - Track Safety Standards; Concrete Crossties

Science.gov (United States)

2011-06-15

...-0007, Notice No. 3] RIN 2130-AC01 Track Safety Standards; Concrete Crossties AGENCY: Federal Railroad... effective concrete crossties, for rail fastening systems connected to concrete crossties, and for automated inspections of track constructed with concrete crossties. The Track Safety Standards were amended via final...

Deflection control system for prestressed concrete bridges by CCD camera. CCD camera ni yoru prestressed concrete kyo no tawami kanri system

Energy Technology Data Exchange (ETDEWEB)

Noda, Y.; Nakayama, Y.; Arai, T. (Kawada Construction Co. Ltd., Tokyo (Japan))

1994-03-15

For the long-span prestressed concrete bridge (continuous box girder and cable stayed bridge), the design and construction control becomes increasingly complicated as construction proceeds because of its cyclic works. This paper describes the method and operation of an automatic levelling module using CCD camera and the experimental results by this system. For this automatic levelling system, the altitude can be automatically measured by measuring the center location of gravity of the target on the bridge surface using CCD camera. The present deflection control system developed compares the measured value by the automatic levelling system with the design value obtained by the design calculation system, and manages them. From the real-time continuous measurement for the long term, in which the CCD camera was set on the bridge surface, it was found that the stable measurement accuracy can be obtained. Successful application of this system demonstrates that the system is an effective and efficient construction aid. 11 refs., 19 figs., 1 tab.

Humectants To Augment Current From Metallized Zinc Cathodic Protection Systems on Concrete

Energy Technology Data Exchange (ETDEWEB)

Holcomb, Gordon R.; Covino Jr., Bernard S.; Cramer, Stephen D.; Russell, James H. Russell; Bullard, Sophie J.; Collins, W. Keith; Bennett, Jack E. (J.E. Bennett Consulting, Inc.); Soltesz, Steven M. (ODOT); Laylor, H. Martin (ODOT)

2002-12-01

Cathodic protection (CP) systems using thermal-sprayed zinc anodes are employed to mitigate the corrosion process in reinforced concrete structures. However, the performance of the anodes is improved by moisture at the anode-concrete interface. Research was conducted to investigate the effect of hydrophilic chemical additives, humectants, on the electrical performance and service life of zinc anodes. Lithium bromide and lithium nitrate were identified as feasible humectants with lithium bromide performing better under galvanic CP and lithium nitrate performing better under impressed current CP. Both humectants improved the electrical operating characteristics of the anode and increased the service life by up to three years.

Innovation in concrete research-review and perspective

International Nuclear Information System (INIS)

Idorn, Gunnar M.

2005-01-01

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

TRANSPARENT CONCRETE

OpenAIRE

Sandeep Sharma*, Dr. O.P. Reddy

2017-01-01

Transparent concrete is the new type of concrete introduced in todays world which carries special property of light transmitting due to presence of light Optical fibres. Which is also known as translucent concrete or light transmitting concrete, it is achieved by replacing coarse aggregates with transparent alternate materials (Optical fibres). The binding material in transparent concrete may be able to transmit light by using clear resins the concrete mix. The concrete used in industry in pr...

Open to a Changing World: Concrete Poetry in Denmark

DEFF Research Database (Denmark)

Ørum, Tania

2010-01-01

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...

DEVELOPMENT OF A SUSTAINABLE CONCRETE WASTE RECYCLING SYSTEM

OpenAIRE

Truptimala Patanaik*; Niharika Patel; Shilpika Panda; Subhasmita Prusty

2016-01-01

Construction solid waste has caused serious environmental problems. Reuse, recycling and reduction of construction materials have been advocated for many years, and various methods have been investigated. There may be six type of building materials: plastic, paper, timber, metal, glass and concrete which can be reused and recycled. This paper examines the rate of reusable & recyclable concrete waste. On the other hand, the reuse of construction waste is highly essential ...

Smart CFRP systems for the controlled retrofitting of reinforced concrete members

Science.gov (United States)

Schaller, M.-B.; Käseberg, S.; Kuhne, M.

2010-09-01

During the last ten years an increasing amount of Carbon Fiber Reinforced Polymer (CFRP) applications to rehabilitate damaged concrete elements was observed. Thereby some important disadvantages of the brittle materials must be considered, for example the low ductility of the bond between CFRP and concrete and brittle failure of FRP. With embedded sensor systems it is possible to measure crack propagation and strains. In this paper a sensor based CFRP system will be presented, that can be used for strengthening and measuring. The used optical fibers with Fiber Bragg Gratings (FBG) have a large number of advantages in opposite to electrical measuring methods. Examples are small dimensions, low weight as well as high static and dynamic resolution of measured values. The main problem during the investigations was the fixing of the glass fiber and the small FBG at the designated position. In this paper the possibility of setting the glass fiber with embroidery at the reinforcing fiber material will be presented. On the basis of four point bending tests on beams (dimensions of 700 x 150 x 150 mm) and tests on wrapped columns the potential of the Smart CFRP system is introduced.

Study on Real-Time Simulation Analysis and Inverse Analysis System for Temperature and Stress of Concrete Dam

Directory of Open Access Journals (Sweden)

Lei Zhang

2015-01-01

Full Text Available In the concrete dam construction, it is very necessary to strengthen the real-time monitoring and scientific management of concrete temperature control. This paper constructs the analysis and inverse analysis system of temperature stress simulation, which is based on various useful data collected in real time in the process of concrete construction. The system can produce automatically data file of temperature and stress calculation and then achieve the remote real-time simulation calculation of temperature stress by using high performance computing techniques, so the inverse analysis can be carried out based on a basis of monitoring data in the database; it fulfills the automatic feedback calculation according to the error requirement and generates the corresponding curve and chart after the automatic processing and analysis of corresponding results. The system realizes the automation and intellectualization of complex data analysis and preparation work in simulation process and complex data adjustment in the inverse analysis process, which can facilitate the real-time tracking simulation and feedback analysis of concrete temperature stress in construction process and enable you to discover problems timely, take measures timely, and adjust construction scheme and can well instruct you how to ensure project quality.

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

Experimental Evaluation of the Failure of a Seismic Design Category - B Precast Concrete Beam-Column Connection System

Science.gov (United States)

2014-12-01

Precast Concrete Beam - Column Connection ...ERDC TR-14-12 December 2014 Experimental Evaluation of the Failure of a Seismic Design Category – B Precast Concrete Beam - Column Connection ...systems in order to develop a methodology and obtain basic insight for predicting the brittle failure of precast beam - column connections under

How Concrete is Concrete

OpenAIRE

Koeno Gravemeijer

2010-01-01

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, 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 diff...

Thermal analysis of dry concrete canister storage system for CANDU spent fuel

International Nuclear Information System (INIS)

Ryu, Yong Ho

1992-02-01

This paper presents the results of a thermal analysis of the concrete canisters for interim dry storage of spent, irradiated Canadian Deuterium Uranium(CANDU) fuel. The canisters are designed to contain 6-year-old fuel safely for periods of 50 years in stainless steel baskets sealed inside a steel-lined concrete shield. In order to assure fuel integrity during the storage, fuel rod temperature shall not exceed the temperature limit. The contents of thermal analysis include the following : 1) Steady state temperature distributions under the conservative ambient temperature and insolation load. 2) Transient temperature distributions under the changes in ambient temperature and insolation load. Accounting for the coupled heat transfer modes of conduction, convection, and radiation, the computer code HEATING5 was used to predict the thermal response of the canister storage system. As HEATING5 does not have the modeling capability to compute radiation heat transfer on a rod-to-rod basis, a separate calculating routine was developed and applied to predict temperature distribution in a fuel bundle. Thermal behavior of the canister is characterized by the large thermal mass of the concrete and radiative heat transfer within the basket. The calculated results for the worst case (steady state with maximum ambient temperature and design insolation load) indicated that the maximum temperature of the 6 year cooled fuel reached to 182.4 .deg. C, slightly above the temperature limit of 180 .deg. C. However,the thermal inertia of the thick concrete wall moderates the internal changes and prevents a rise in fuel temperature in response to ambient changes. The maximum extent of the transient zone was less than 75% of the concrete wall thickness for cyclic insolation changes. When transient nature of ambient temperature and insolation load are considered, the fuel temperature will be a function of the long term ambient temperature as opposed to daily extremes. The worst design

Effect of insulating concrete forms in concrete compresive strength

Science.gov (United States)

Martinez Jerez, Silvio R.

The subject presented in this thesis is the effect of Insulating Concrete Forms (ICF's) on concrete compressive strength. This work seeks to identify if concrete cured in ICF's has an effect in compressive strength due to the thermal insulation provided by the forms. Modern construction is moving to energy efficient buildings and ICF's is becoming more popular in new developments. The thesis used a concrete mixture and a mortar mixture to investigate the effects of ICF's on concrete compressive strength. After the experimentations were performed, it was concluded that the ICF's do affect concrete strength. It was found that the forms increase concrete strength without the need for additional curing water. An increase of 50% in strength at 56 days was obtained. It was concluded that the longer concrete cures inside ICF's, the higher strength it reaches, and that ICF's effect on concrete strength is proportional to volume of concrete.

Reviewing the Carbonation Resistance of Concrete

Directory of Open Access Journals (Sweden)

S P Singh

2016-07-01

Full Text Available The paper reviews the studies on one of the important durability properties of concrete i.e. Carbonation. One of the main causes of deterioration of concrete is carbonation, which occurs when carbon dioxide (CO2 penetrates the concrete’s porous system to create an environment with lower pH around the reinforcement in which corrosion can proceed. Carbonation is a major cause of degradation of concrete structures leading to expensive maintenance and conservation operations. Herein, the importance, process and effect of various parameters such as water/cement ratio, water/binder ratio, curing conditions, concrete cover, super plasticizers, type of aggregates, grade of concrete, porosity, contaminants, compaction, gas permeability, supplementary cementitious materials (SCMs/ admixtures on the carbonation of concrete has been reviewed. Various methods for estimating the carbonation depth are also reported briefly

Estimation of Prestress Force Distribution in the Multi-Strand System of Prestressed Concrete Structures

Directory of Open Access Journals (Sweden)

Keunhee Cho

2015-06-01

Full Text Available Prestressed concrete (PSC is one of the most reliable, durable and widely used construction materials, which overcomes the weakness of concrete in tension by the introduction of a prestress force. Smart strands enabling measurement of the prestress force have recently been developed to maintain PSC structures throughout their lifetime. However, the smart strand cannot give a representative indication of the whole prestress force when used in multi-strand systems since each strand sustains a different prestress force. In this paper, the actual distribution of the prestress force in a multi-strand system is examined using elastomagnetic (EM sensors to develop a method for tracking representative indicators of the prestress force using smart strands.

Estimation of Prestress Force Distribution in the Multi-Strand System of Prestressed Concrete Structures.

Science.gov (United States)

Cho, Keunhee; Park, Sung Yong; Cho, Jeong-Rae; Kim, Sung Tae; Park, Young-Hwan

2015-06-15

Prestressed concrete (PSC) is one of the most reliable, durable and widely used construction materials, which overcomes the weakness of concrete in tension by the introduction of a prestress force. Smart strands enabling measurement of the prestress force have recently been developed to maintain PSC structures throughout their lifetime. However, the smart strand cannot give a representative indication of the whole prestress force when used in multi-strand systems since each strand sustains a different prestress force. In this paper, the actual distribution of the prestress force in a multi-strand system is examined using elastomagnetic (EM) sensors to develop a method for tracking representative indicators of the prestress force using smart strands.

Empirical Validation of Heat Transfer Performance Simulation of Graphite/PCM Concrete Materials for Thermally Activated Building System

Directory of Open Access Journals (Sweden)

Jin-Hee Song

2017-01-01

Full Text Available To increase the heat capacity in lightweight construction materials, a phase change material (PCM can be introduced to building elements. A thermally activated building system (TABS with graphite/PCM concrete hollow core slab is suggested as an energy-efficient technology to shift and reduce the peak thermal load in buildings. An evaluation of heat storage and dissipation characteristics of TABS in graphite/PCM concrete has been conducted using dynamic simulations, but empirical validation is necessary to acceptably predict the thermal behavior of graphite/PCM concrete. This study aimed to validate the thermal behavior of graphite/PCM concrete through a three-dimensional transient heat transfer simulation. The simulation results were compared to experimental results from previous studies of concrete and graphite/PCM concrete. The overall thermal behavior for both materials was found to be similar to experiment results. Limitations in the simulation modeling, which included determination of the indoor heat transfer coefficient, assumption of constant thermal conductivity with temperature, and assumption of specimen homogeneity, led to slight differences between the measured and simulated results.

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 ...

EXPERIMENTAL INVESTIGATION ON THE EFFECT OF NATURAL TROPICAL WEATHER ON INTERFACIAL BONDING PERFORMANCE OF CFRP-CONCRETE BONDING SYSTEM

Directory of Open Access Journals (Sweden)

MOHD H. MOHD HASHIM

2016-04-01

Full Text Available The existing reinforced concrete structures may require rehabilitation and strengthening to overcome deficiencies due to defect and environmental deterioration. Fibre Reinforced Polymer (FRP-concrete bonding systems can provide solution for the deficiencies, but the durability of the bonded joint needs to be investigated for reliable structural performance. In this research the interfacial bonding behaviour of CFRP-concrete system under tropical climate exposure is main interest. A 300 mm concrete prism was bonded with CFRP plate on its two sides and exposed for 3, 6, and 9 months to laboratory environment, continuous natural weather, and wet-dry exposure in 3.5% saltwater solution at room and 40 °C temperature. The prisms were subjected to tension and compression load under bonding test to measure the strain and determine stress distribution and shear stress transfer behaviour. The results of the bonding test showed that load transfer was fairly linear and uniform at lower load level and changed to non-linear and non- uniform at higher load level. The force transfers causes the shear stress distribution being shifted along the bonded length. The combination of climate effects may have provided better curing of the bonded joints, but longer duration of exposure may be required to weaken the bond strength. Nevertheless, CFRP-concrete bonding system was only minimally affected under the tropical climate and salt solution.

Concrete

DEFF Research Database (Denmark)

2015-01-01

Concrete is a component of coherent transition between a concrete base and a wooden construction. The structure is based on a quantity of investigations of the design possibilities that arise when combining digital fabrication tools and material capacities. Through tangible experiments the project...... specific for this to happen. And the knowledge and intention behind the drawing becomes specialised through the understanding of the fabrication processes and their affect on the materials.The structure Concrete is a result of a multi-angled kerf series in ash wood and a concrete base. The ash wood is cut...... using a 5-axis CNC router with a thin saw blade attached. The programming of the machining results in variations of kerfs that lets the ash wood twist into unique shapes.The shapes of the revolving ash ribbons continue into the concrete creating a cohesive shape. The form for the concrete itself is made...

Fast Lamb wave energy shift approach using fully contactless ultrasonic system to characterize concrete structures

Science.gov (United States)

Ham, Suyun; Popovics, John S.

2015-03-01

Ultrasonic techniques provide an effective non-destructive evaluation (NDE) method to monitor concrete structures, but the need to perform rapid and accurate structural assessment requires evaluation of hundreds, or even thousands, of measurement datasets. Use of a fully contactless ultrasonic system can save time and labor through rapid implementation, and can enable automated and controlled data acquisition, for example through robotic scanning. Here we present results using a fully contactless ultrasonic system. This paper describes our efforts to develop a contactless ultrasonic guided wave NDE approach to detect and characterize delamination defects in concrete structures. The developed contactless sensors, controlled scanning system, and employed Multi-channel Analysis of Surface Waves (MASW) signal processing scheme are reviewed. Then a guided wave interpretation approach for MASW data is described. The presence of delamination is interpreted by guided plate wave (Lamb wave) behavior, where a shift in excited Lamb mode phase velocity, is monitored. Numerically simulated and experimental ultrasonic data collected from a concrete sample with simulated delamination defects are presented, where the occurrence of delamination is shown to be associated with a mode shift in Lamb wave energy.

Build-up Factor Calculation for Ordinary Concrete, Baryte Concrete and Blast-furnace Slugges Concrete as γ Radiation Shielding

International Nuclear Information System (INIS)

Isman MT; Elisabeth Supriatni; Tochrul Binowo

2002-01-01

Calculation of build up factor ordinary concrete, baryte concrete and blast-furnace sludge concrete have been carried out. The calculations have been carried out by dose rate measurement of Cs 137 source before and after passing through shielding. The investigated variables were concrete type, thickness of concrete and relative possession of concrete. Concrete type variables are ordinary concrete, baryte concrete and blast sludge furnace concrete. The thickness variables were 6, 12, 18, 24, 30 and 36 cm. The relative position variables were dose to the source and close to detector. The result showed that concrete type and position did not have significant effect to build-up factor value, while the concrete thickness (r) and the attenuation coefficient (μ) were influenced to the build-up factor. The higher μr value the higher build-up factor value. (author)

Concrete mixtures with high-workability for ballastless slab tracks

OpenAIRE

Olga Smirnova

2017-01-01

The concrete track-supporting layer and the monolithic concrete slab of ballastless track systems are made in-situ. For this reason the concrete mixtures of high workability should be used. Influence of the sand kind, the quartz microfiller fineness and quantity as well as quantity of superplasticizer on workability of fresh concrete and durability of hardened concrete is shown. The compositions of the high-workability concrete mixtures with lower consumption of superplasticizer are developed...

Assessment of permeation quality of concrete through mercury intrusion porosimetry

International Nuclear Information System (INIS)

Kumar, Rakesh; Bhattacharjee, B.

2004-01-01

Permeation quality of laboratory cast concrete beams was determined through initial surface absorption test (ISAT). The pore system characteristics of the same concrete beam specimens were determined through mercury intrusion porosimetry (MIP). Data so obtained on the measured initial surface absorption rate of water by concrete and characteristics of pore system of concrete estimated from porosimetry results were used to develop correlations between them. Through these correlations, potential of MIP in assessing the durability quality of concrete in actual structure is demonstrated

Bacteria-based concrete: from concept to market

Science.gov (United States)

Wiktor, V.; Jonkers, H. M.

2016-08-01

The concept of self-healing concrete—a concrete which can autonomously repair itself after crack formation, with no or limited human intervention—has received a lot of attention over the past 10 years as it could help structures to last longer and at a lower maintenance cost. This paper gives an overview on the key aspects and recent advances in the development of the bacteria-based self-healing concrete developed at the University of Technology of Delft (The Netherlands). Research started with the screening and selection of concrete compatible bacteria and nutrients. Several types of encapsulated bacteria and nutrients have been developed and tested. The functionality of these healing agents was demonstrated by showing metabolic activity of activated bacterial spores by oxygen consumption measurements and by regain of material functionality in form of regain of water tightness. Besides development of bacteria-based self-healing concrete, a bacteria-based repair mortar and liquid system were developed for the treatment of aged concrete structures. Field trials have been carried out with either type of bacteria-based systems and the promising results have led to a spinoff company Basilisk Self-Healing Concrete with the aim to further develop these systems and bring them to the market.

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.

Investigation on integrity of JMTR concrete structures, cooling system and utility facilities

International Nuclear Information System (INIS)

Ebisawa, Hiroyuki; Tobita, Kenji; Fukasaku, Akitomi; Kaminaga, Masanori

2010-02-01

The condition of facilities and components to be used for re-operation of the Japan Materials Testing Reactor (JMTR) from FY2011, was investigated before the refurbishment work. An investigation of aged components (aged-investigation) was carried out for concrete structures of the JMTR reactor building, exhaust stack, trench, canal, filter banks and for aged components of tanks in the primary cooling system, heat exchangers, pipes in the secondary cooling system, cooling tower, emergency generators and so on, in order to identify their integrity. The aged-investigation was carried out from the beginning of FY2007. As a result, cracks of concrete structures such as the exhaust stack, a foundation of the UCL (Utility Cooling Line) elevated water tank were repaired and pipe linings of secondary cooling system were replaced. Motors of primary cooling pumps, pumps in the secondary cooling system and in other systems were decided to replace from viewpoints of future maintenance and improvement of reliability. Other components and the reactor building were decided to use continuously for a long-term by appropriate maintenance activities based on the long-term maintenance plan. In this paper, the aged-investigation for the JMTR reactor building, heat exchangers and emergency generators is presented. (author)

NANOMODIFIED CONCRETE

Directory of Open Access Journals (Sweden)

B. M. Khroustalev

2015-01-01

Full Text Available One of the main directions in construction material science is the development of  next generation concrete that is ultra-dense, high-strength, ultra-porous, high heat efficient, extra corrosion-resistant. Selection of such direction is caused by extreme operational impacts on the concrete, namely: continuously increasing load on the concrete and various dynamics of such loads; the necessity in operation of concrete products in a wide temperature range and their exposure to various chemical and physical effects.The next generation concrete represents high-tech concrete mixtures with additives that takes on and retain the required properties when hardening and being used under any operational conditions. A differential characteristic of the next generation concrete is its complexity that presumes usage of various mineral dispersed components, two- and three fractional fine and coarse aggregates, complex chemical additives, combinations of polymer and iron reinforcement.Design strength and performance properties level of the next generation concrete is achieved by high-quality selection of the composition, proper selection of manufacturing techniques, concrete curing, bringing the quality of concrete items to the required level of technical condition during the operational phase. However, directed formation of its structure is necessary in order to obtain high-tech concrete.Along with the traditional methods for regulation of the next generation concrete structure, modification of concrete while using silica nanoparticles is also considered as a perspective one because the concrete patterning occurs due to introduction of a binder in a mineral matrix. Due to this it is possible to obtain nano-modified materials with completely new properties.The main problem with the creation of nano-modified concrete is a uniform distribution of nano-materials in the volume of the cement matrix which is particularly important in the cases of adding a modifier in

Reduced labor and condensed schedules with cellular concrete solutions

Energy Technology Data Exchange (ETDEWEB)

Lavis, D. [CEMATRIX Inc., Calgary, AB (Canada)

2008-07-01

This paper discussed the use of cellular concrete materials in oil sands tank base foundation systems, shallow buried utility insulation systems, roadways, slabs, and buried modules. The concrete is formed from Portland cement, water, specialized pre-formed foaming agents, and air mixed in controlled proportions. Fly ash and polypropylene or glass fibers can also be used as additions. Cellular concrete can often be used to speed up construction and minimize labour requirements. Cellular concrete can be cast-in-place, and has soil-stabilizing and self-compacting features. The concrete can be produced and placed on-site at rates exceeding 120 cubic meters per hour. Cellular concrete can be pumped into place over long distances through flexible hoses. A case study comparing the cellular concrete to traditional plastic foam insulation was used to demonstrate the equivalency and adequacy of insulation, structural properties and installation costs. The study showed that although the cellular concrete had a high installation cost, greater compressive strength was gained. The concrete was self-levelling and did not require compaction or vibration. The use of the cellular concrete resulted in an accelerated construction schedule. 6 refs., 2 tabs., 6 figs.

Concrete mixtures with high-workability for ballastless slab tracks

Directory of Open Access Journals (Sweden)

Olga Smirnova

2017-10-01

Full Text Available The concrete track-supporting layer and the monolithic concrete slab of ballastless track systems are made in-situ. For this reason the concrete mixtures of high workability should be used. Influence of the sand kind, the quartz microfiller fineness and quantity as well as quantity of superplasticizer on workability of fresh concrete and durability of hardened concrete is shown. The compositions of the high-workability concrete mixtures with lower consumption of superplasticizer are developed. The results of the research can be recommended for high performance concrete of ballastless slab track.

Dismantling system of concrete thermal shielding walls

International Nuclear Information System (INIS)

Machida, Nobuhiro; Saiki, Yoshikuni; Ono, Yorimasa; Tokioka, Masatake; Ogino, Nobuyuki.

1985-01-01

Purpose: To enable safety and efficient dismantling of concrete thermal shielding walls in nuclear reactors. Method: Concrete thermal shielding walls are cut and dismantled into dismantled blocks by a plasma cutting tool while sealing the top opening of bioshielding structures. The dismantled blocks are gripped and conveyed. The cutting tool is remote-handled while monitoring on a television receiver. Slugs and dusts produced by cutting are removed to recover. Since the dismantling work is carried out while sealing the working circumstance and by the remote control of the cutting tool, the operators' safety can be secured. Further, since the thermal sealing walls are cut and dismantled into blocks, dismantling work can be done efficiently. (Moriyama, K.)

A review on carbonation study in concrete

Science.gov (United States)

Venkat Rao, N.; Meena, T.

2017-11-01

In this paper the authors have reviewed the carbonation studies which are a vital durability property of concrete. One of the major causes for deterioration and destruction of concrete is carbonation. The mechanism of carbonation involves the penetration carbon dioxide (CO2) into the concrete porous system to form an environment by reducing the pH around the reinforcement and initiation of the corrosion process. The paper also endeavours to focus and elucidate the gravity of importance, the process and chemistry of carbonate and how the various parameters like water/cement ratio, curing, depth of concrete cones, admixtures, grade of concrete, strength of concrete, porosity and permeability effect carbonation in concrete. The role of Supplementary Cementitious Materials (SCMs) like Ground granulated Blast Furnace Slag (GGBS) and Silica Fume (SF) has also been reviewed along with the influence of depth of carbonation.

Nuclear Power Plant Concrete Structures

Energy Technology Data Exchange (ETDEWEB)

Basu, Prabir [International Atomic Energy Agency (IAEA); Labbe, Pierre [Electricity of France (EDF); Naus, Dan [Oak Ridge National Laboratory (ORNL)

2013-01-01

A nuclear power plant (NPP) involves complex engineering structures that are significant items of the structures, systems and components (SSC) important to the safe and reliable operation of the NPP. Concrete is the commonly used civil engineering construction material in the nuclear industry because of a number of advantageous properties. The NPP concrete structures underwent a great degree of evolution, since the commissioning of first NPP in early 1960. The increasing concern with time related to safety of the public and environment, and degradation of concrete structures due to ageing related phenomena are the driving forces for such evolution. The concrete technology underwent rapid development with the advent of chemical admixtures of plasticizer/super plasticizer category as well as viscosity modifiers and mineral admixtures like fly ash and silica fume. Application of high performance concrete (HPC) developed with chemical and mineral admixtures has been witnessed in the construction of NPP structures. Along with the beneficial effect, the use of admixtures in concrete has posed a number of challenges as well in design and construction. This along with the prospect of continuing operation beyond design life, especially after 60 years, the impact of extreme natural events ( as in the case of Fukushima NPP accident) and human induced events (e.g. commercial aircraft crash like the event of September 11th 2001) has led to further development in the area of NPP concrete structures. The present paper aims at providing an account of evolution of NPP concrete structures in last two decades by summarizing the development in the areas of concrete technology, design methodology and construction techniques, maintenance and ageing management of concrete structures.

Performance evaluation of corrosion-affected reinforced concrete ...

Indian Academy of Sciences (India)

M B Anoop

Abstract. A methodology for performance evaluation of reinforced concrete bridge girders in corrosive ... concrete (RC) members of infrastructural systems, espe- ... bility will be useful for making engineering decisions for ...... Water-cement ratio.

The concreteness effect: evidence for dual coding and context availability.

Science.gov (United States)

Jessen, F; Heun, R; Erb, M; Granath, D O; Klose, U; Papassotiropoulos, A; Grodd, W

2000-08-01

The term concreteness effect refers to the observation that concrete nouns are processed faster and more accurately than abstract nouns in a variety of cognitive tasks. Two models have been proposed to explain the neuronal basis of the concreteness effect. The dual-coding theory attributes the advantage to the access of a right hemisphere image based system in addition to a verbal system by concrete words. The context availability theory argues that concrete words activate a broader contextual verbal support, which results in faster processing, but do not access a distinct image based system. We used event-related fMRI to detect the brain regions that subserve to the concreteness effect. We found greater activation in the lower right and left parietal lobes, in the left inferior frontal lobe and in the precuneus during encoding of concrete compared to abstract nouns. This makes a single exclusive theory unlikely and rather suggests a combination of both models. Superior encoding of concrete words in the present study may result from (1) greater verbal context resources reflected by the activation of left parietal and frontal associative areas, and (2) the additional activation of a non-verbal, perhaps spatial imagery-based system, in the right parietal lobe. Copyright 2000 Academic Press.

High Performance Concrete

Directory of Open Access Journals (Sweden)

Traian Oneţ

2009-01-01

Full Text Available The paper presents the last studies and researches accomplished in Cluj-Napoca related to high performance concrete, high strength concrete and self compacting concrete. The purpose of this paper is to raid upon the advantages and inconveniences when a particular concrete type is used. Two concrete recipes are presented, namely for the concrete used in rigid pavement for roads and another one for self-compacting concrete.

Studies of detailed biofilm characterization on fly ash concrete in comparison with normal and superplasticizer concrete in seawater environments.

Science.gov (United States)

Vishwakarmaa, Vinita; George, R P; Ramachandran, D; Anandkumar, B; Mudalib, U Kamachi

2014-01-01

In cooling water systems, many concrete structures in the form of tanks, pillars and reservoirs that come in contact with aggressive seawater are being deteriorated by chemical and biological factors. The nuclear industry has decided to partially replace the Portland cement with appropriate pozzolans such as fly ash, which could densify the matrix and make the concrete impermeable. Three types of concrete mixes, viz., normal concrete (NC), concrete with fly ash and superplasticizer (FA) and concrete with only superplasticizer (SP) were fabricated for short- and long-term exposure studies and for screening out the better concrete in seawater environments. Biofilm characterization studies and microscopic studies showed excellent performance of FA concrete compared to the other two. Laboratory exposure studies in pure cultures of Thiobacillus thiooxidans and Fusarium oxysporum were demonstrated for the inhibition of microbial growth on fly ash. Epifluorescence and scanning electron microscopic studies supported the better performance of the FA specimen. Thus, the present study clearly showed that FA concrete is less prone to biofilm formation and biodeterioration.

Failure Modes in Concrete Repair Systems due to Ongoing Corrosion

NARCIS (Netherlands)

Lukovic, M.; Šavija, B.; Ye, G.; Schlangen, H.E.J.G.; van Breugel, K.

2017-01-01

Corrosion of steel reinforcement is the main cause of deterioration in reinforced concrete structures. It can result in cracking and spalling of the concrete cover. After the damaged cover is repaired, reinforcement corrosion might continue and even accelerate. While the development of the corrosion

The state of the Primary Degradation Factors and Models of Concrete Cask in Spent Fuel Dry Storage System

International Nuclear Information System (INIS)

Kim, J. S.; Lee, K. S.; Choi, J. W.; Kwon, S.

2010-01-01

In South Korea, a total of twenty nuclear reactors are in operation; the cumulative amount of spent fuel is estimated to be 10,490 MTU in 2009. The full capacity of the waste storage is expected to be saturated in around 2016. However, a national strategy for spent fuel management has not yet been set down and high level waste (HLW) such as spent fuel will have to be stored at-reactor (AR) by re-racking. Recently an worldwide interest on the dry storage has increased especially around U.S. With a perspective of the material of the spent fuel dry storage cask, the system can be divided into two types of metal and concrete casks. The concrete type cask is a very attractive option because of the cost competitiveness of concrete material and its relatively long-term durability. Although the type of metal cask is chosen, the use of cementitious material is inevitable at least for the cask foundation and the facilities for the protection of dry storage structures. Upon being placed, the performance of concrete begins to deteriorate from the intrinsic change of cement and the physical/ chemical environmental conditions. Thus it is necessary to evaluate the durability of a concrete for the increase of reliability and safety of the whole system during the designed life time. Considering the dry storage system of spent fuel is the item which can create a lot of added value, the development of a dry storage cask is usually initiated by private enterprises among developed countries. The detail research results and specific design criteria for the safety assessment of a concrete cask have not been revealed to the public well. In this paper, the major expected degradation factors and related degradation models of concrete casks were investigated as part of the safety assessment by taking account of the site where Korea industrial nuclear power plants are located

How Concrete is Concrete?

Directory of Open Access Journals (Sweden)

Koeno Gravemeijer

2011-01-01

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.Key words:  Conceret Learning Materials, School Math, Common Sense, Scaffolding, Communication DOI: http://dx.doi.org/10.22342/jme.2.1.780.1-14

Properties of high-workability concrete with recycled concrete aggregate

OpenAIRE

Safiuddin,; Alengaram,Ubagaram Johnson; Salam,Abdus; Jumaat,Mohd Zamin; Jaafar,Fahrol Fadhli; Saad,Hawa Binti

2011-01-01

This study presents the effects of recycled concrete aggregate (RCA) on the key fresh and hardened properties of concrete. RCA was used to produce high-workability concrete substituting 0-100% natural coarse aggregate (NCA) by weight. The slump and slump flow of fresh concretes were determined to ensure high workability. In addition, the compressive, flexural and splitting tensile strengths, modulus of elasticity, and permeable voids of hardened concretes were determined. The test results rev...

Clogging in permeable concrete: A review.

Science.gov (United States)

Kia, Alalea; Wong, Hong S; Cheeseman, Christopher R

2017-05-15

Permeable concrete (or "pervious concrete" in North America) is used to reduce local flooding in urban areas and is an important sustainable urban drainage system. However, permeable concrete exhibits reduction in permeability due to clogging by particulates, which severely limits service life. This paper reviews the clogging mechanism and current mitigating strategies in order to inform future research needs. The pore structure of permeable concrete and characteristics of flowing particulates influence clogging, which occurs when particles build-up and block connected porosity. Permeable concrete requires regular maintenance by vacuum sweeping and pressure washing, but the effectiveness and viability of these methods is questionable. The potential for clogging is related to the tortuosity of the connected porosity, with greater tortuosity resulting in increased potential for clogging. Research is required to develop permeable concrete that can be poured on-site, which produces a pore structure with significantly reduced tortuosity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Odua Weston Jambi Hotel’s Structural Building Design with Prestressed Concrete Slab System Approach

Science.gov (United States)

Bayuaji, R.; Darmawan, M. S.; Rofiq, M. A.; Santoso, S. E.; Hardiyanto, E.

2017-11-01

Odua Weston Jambi Hotel is an eight-floor hotel and located in a prone to earth-quake area. This building used conventional concrete to its structural beam and column. This research’s purpose was to maximize the second-floor’s function by modifing its architectural design. Special Moment Resisting Frame System (SMRFS) approach was used in the structural design, referred to SNI 03-2847-2013 dan SNI 1726-2012 and to compensate the needs of a spacious hall without any column in the centre of the hall, so therefore, prestressed concrete plate is used to solve this problem.

Concrete Waste as a Cement Replacement Material in Concrete Blocks for Optimization of Thermal and Mechanical Properties

OpenAIRE

Rosman M.S.; Abas N.F.; Othuman Mydin M.A.

2014-01-01

The sustainability of the natural environment and eco-systems is of great importance. Waste generated from construction forces mankind to find new dumping grounds and at the same time, more natural resources are required for use as construction materials. In order to overcome this problem, this study was conducted to investigate the use of concrete waste in concrete blocks with a special focus on the thermal and mechanical properties of the resulting products. Three varieties of concrete mixt...

COMPARATIVE STUDY OF GLASS FIBRE CONCRETE AND NORMAL CONCRETE

OpenAIRE

Mr.Yogesh S.Lanjewar*

2018-01-01

Concrete is basically the most important material concerning with the construction and infrastructural procedures, for which it should be of good strength and durability. Many researches are being conducted to make concrete more sustainable and of more strength and durability. Therefore keeping this in mind i have chosen to do the comparative study regarding the strength of normal concrete with the glass fibre added concrete using mix design procedure as per IS 10262-2009 for concrete. As w...

Study of technological features of tubular compressed concrete members in concreting

Directory of Open Access Journals (Sweden)

Voskobiinyk Olena

2017-01-01

Full Text Available The technological features of core concreting were analyzed as the main factor in ensuring of strength and reliability of compressed concrete-filled steel tubular (CFST members. We have conducted the analysis of existing concreting methods of CFST members. In this respect, the most dangerous types of possible technological defects of concrete core of CFST members are inhomogeneity along the height, voids, caverns, and concrete “weak spots”. The authors considered the influence of such technological factors of concreting: placeability, time, concrete mixture compaction method, concreting height on the concrete core strength of CFST members. Based on the experimental studies conducted we suggested the regression correlations for determining the concrete strength of CFST members of different length depending on the movability of concrete mixture and a time for its compaction. The authors performed the correlation analysis of technological factors of concreting on the strength of the concrete core. We carried out the comparison of data on the concrete core strength of CFST members, that were determined by non-destructive methods (sclerometer test results, ultrasonic method and direct compression strength tests. We experimentally proved that using movable mixtures with the slump of about 4 – 9 cm the overall variation coefficient of concrete core strength of CFST members along the height reaches nearly 13%. Based on the experimental studies conducted we suggested the guidelines on optimal regimes of concrete compaction during manufacturing CFST members at a construction site environment.

Study of the performance of four repairing material systems for hydraulic structures of concrete dams

Directory of Open Access Journals (Sweden)

Kormann A. C. M.

2003-01-01

Full Text Available Four types of repairing materials are studied as function of either a conventional concrete or a reference-concrete (RefC, these are: polymer-modified cement mortar (PMor, steel fiber concrete (SFco, epoxy mortar (EMor and silica fume mortar (SFmo, to be applied in hydraulic structures surfaces subjected to a high velocity water flow. Besides the mechanical requests and wearing resistance of hydraulic concrete dam structures, especially the spillway surfaces, the high solar radiation, the environmental temperature and wet and dry cycles, contribute significantly to the reduction of their lifespan. RefC and the SFco were developed based on a usual concrete mixture used in slabs of spillways. The average RefC mixture used was 1: 1.61: 2.99: 0.376, with Pozzolan-modified Portland cement consumption of 425 kg/m³. EMor and PMor mixtures followed the information given by the manufacturers and lab experience. Tests on concrete samples were carried out in laboratory simulating normally found environmental situations in order to control the mechanical resistance and the aging imposed conditions, such as solar radiation and humidity. Also, physicochemical characterizing tests were made for all used materials. From the analyzed results, two of them presented a higher performance: the EMor and SFmo. SFco presented good adherence to the RefC and good mechanical performance. However, it also presented apparent metal corrosion in humidity tests, being indicated for use, with caution, as an intermediate layer in underwater repairs. In a general classification, considering all tests, including their field applications, the better performance material systems were EMor- SFmo> SFco> PMor.

Glazed Concrete

DEFF Research Database (Denmark)

Bache, Anja Margrethe

2010-01-01

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

Properties of concretes produced with waste concrete aggregate

International Nuclear Information System (INIS)

Topcu, Ilker Bekir; Sengel, Selim

2004-01-01

An environmentally friendly approach to the disposal of waste materials, a difficult issue to cope with in today's world, would only be possible through a useful recycling process. For this reason, we suggest that clearing the debris from destroyed buildings in such a way as to obtain waste concrete aggregates (WCA) to be reused in concrete production could well be a partial solution to environmental pollution. For this study, the physical and mechanical properties along with their freeze-thaw durability of concrete produced with WCAs were investigated and test results presented. While experimenting with fresh and hardened concrete, mixtures containing recycled concrete aggregates in amounts of 30%, 50%, 70%, and 100% were prepared. Afterward, these mixtures underwent freeze-thaw cycles. As a result, we found out that C16-quality concrete could be produced using less then 30% C14-quality WCA. Moreover, it was observed that the unit weight, workability, and durability of the concretes produced through WCA decreased in inverse proportion to their endurance for freeze-thaw cycle

POROUS STRUCTURE OF ROAD CONCRETE

Directory of Open Access Journals (Sweden)

M. K. Pshembaev

2016-01-01

Full Text Available Having a great number of concrete structure classifications it is recommended to specify the following three principal types: microstructure – cement stone structure; mesostructure – structure of cement-sand mortar in concrete; macrostucture – two-component system that consists of mortar and coarse aggregate. Every mentioned-above structure has its own specific features which are related to the conditions of their formation. Thus, microstructure of cement stone can be characterized by such structural components as crystal intergrowth, tobermorite gel, incompletely hydrated cement grains and porous space. The most important technological factors that influence on formation of cement stone microstructure are chemical and mineralogical cement composition, its grinding fineness, water-cement ratio and curing condition. Specific cement stone microstructure is formed due to interrelation of these factors. Cement stone is a capillary-porous body that consists of various solid phases represented predominantly by sub-microcrystals of colloidal dispersion. The sub-microcrystals are able adsorptively, osmotically and structurally to withhold (to bind some amount of moisture. Protection of road concrete as a capillary-porous body is considered as one of the topical issues. The problem is solved with the help of primary and secondary protection methods. Methods of primary protection are used at the stage of designing, preparation and placing of concrete. Methods of secondary protection are applied at the operational stage of road concrete pavement. The paper considers structures of concrete solid phase and characteristics of its porous space. Causes of pore initiation, their shapes, dimensions and arrangement in the concrete are presented in the paper. The highest hazard for road concrete lies in penetration of aggressive liquid in it and moisture transfer in the cured concrete. Water permeability of concrete characterizes its filtration factor which

Concrete Hinges

DEFF Research Database (Denmark)

Halding, Philip Skov; Hertz, Kristian Dahl; Schmidt, Jacob Wittrup

2014-01-01

In the first part of the 20th century concrete hinges developed by Freyssinet and Mesnager were widely tested and implemented in concrete structures. The concrete hinges were used a great deal in closed-spandrel arch bridges. Since such a bridge type has not been competitive for the past 40 years......, the research in concrete hinges has not evolved significantly in that period. But introducing a new state-of-the-art concrete arch bridge solution (Pearl-Chain arches invented at the Technical University of Denmark) creates a necessity of a concrete hinge research based on modern standards. Back when research...... in concrete hinges was more common different designs were proposed for the geometry and reinforcement. Previous research focused on fatigue, multi-axial stresses around the hinge throat, and the relation between rotation- and moment. But many different test-setups were proposed by different researchers...

Effect of high temperature or fire on heavy weight concrete properties

International Nuclear Information System (INIS)

Sakr, K.; EL-Hakim, E.

2005-01-01

Temperature plays an important role in the use of concrete for shielding nuclear reactors. In the present work, the effect of different durations (1, 2 and 3 h) of high temperatures (250, 500, 750 and 950 deg. C) on the physical, mechanical and radiation properties of heavy concrete was studied. The effect of fire fitting systems on concrete properties was investigated. Results showed that ilmenite concrete had the highest density, modulus of elasticity and lowest absorption percent, and it had also higher values of compressive, tensile, bending and bonding strengths than gravel or baryte concrete. Ilmenite concrete showed the highest attenuation of transmitted gamma rays. Firing (heating) exposure time was inversely proportional to mechanical properties of all types of concrete. Ilmenite concrete was more resistant to elevated temperature. Foam or air proved to be better than water as a cooling system in concrete structure exposed to high temperature because water leads to a big damage in concrete properties

Sodium-concrete reactions experiments and code development

International Nuclear Information System (INIS)

Casselman, C.; Malet, J.C.; Dufresne, J.; Bolvin, M.

1988-01-01

Hypothesis of hot sodium leak in a fast breeder reactor implies, for the safety organism to consider spillage of sodium on concrete. This safety analysis involves the understanding of sodium-concrete reactions, the knowledge of their consequences and to test the choiced preventive solutions. In association with EDF, the nuclear safety department had carried out an extensive experimental program, the different parts of which are connected with each aspect of this problem: - firstly, interaction between sodium and bare surface of usual concrete; - secondly, the case of a sodium spillage on a concrete surface covered with a defected liner; - thirdly, special concrete tests for a comparison with usual concrete behavior, in direct contact with hot sodium; - at last, a test which concerns a new design with a layer of the selected concrete protected with a defected liner. On the same time, theoretical work leads to elaborate a physical model to describe temporal evolution of thermal and chemical decomposition of a concrete slab under hot sodium action. SORBET-REBUS system will use quoted above test results to its validation

Significance of tests and properties of concrete and concrete-making materials

CERN Document Server

Pielert, James H

2006-01-01

Reflects a decade of technological changes in concrete industry! The newest edition of this popular ASTM publication reflects the latest technology in concrete and concrete-making materials. Six sections cover: (1) General information on the nature of concrete, sampling, variability, and testing laboratories. A new chapter deals with modeling cement and concrete properties. (2) Properties of freshly mixed concrete. (3) Properties of hardened concrete. (4) Concrete aggregates—this section has been revised and the chapters are presented in the order that most concerns concrete users: grading, density, soundness, degradation resistance, petrographic examination, reactivity, and thermal properties. (5) Materials other than aggregates—the chapter on curing materials now reflects the current technology of materials applied to new concrete surfaces. The chapter on mineral admixtures has been separated into two chapters: supplementary cementitious materials and ground slag. (6) Specialized concretes—contains a ...

Design of ultra-lightweight concrete: towards monolithic concrete structures

Directory of Open Access Journals (Sweden)

Yu Qing Liang

2014-04-01

Full Text Available This study addresses the development of ultra-lightweight concrete. A moderate strength and an excellent thermal conductivity of the lightweight concrete are set as the design targets. The designed lightweight aggregates concrete is targeted to be used in monolithic concrete façade structure, performing as both load bearing element and thermal insulator. The developed lightweight concrete shows excellent thermal properties, with a low thermal conductivity of about 0.12 W/(m·K; and moderate mechanical properties, with 28-day compressive strengths of about 10-12 N/mm . This combination of values exceeds, to the researchers’ knowledge, the performance of all other lightweight building materials. Furthermore, the developed lightweight concrete possesses excellent durability properties.

Developing a computerized aging management system for concrete structures in finnish nuclear power plants

International Nuclear Information System (INIS)

Al-Neshawy, F.; Piironen, J.; Sistonen, E.; Vesikari, E.; Tuomisto, M.; Hradil, P.; Ferreira, M.

2013-01-01

Finland has four nuclear reactors units in two power plants. The first unit started operation in 1977 and in the early 1980's all four units were in use. During the last few years the aging management of the Nuclear Power Plant's (NPP) concrete structures has grown an important issue because the existing structures are reaching the end of their licensed operating lifetime (about 40 years). Therefore the nuclear power companies are developing aging management systems to avoid premature degradation of NPP facilities and to be able to extend their operating lifetime. This paper is about the development of a computerized ageing management system for the nuclear power plants concrete structures. The computerized ageing management system is built upon central database and implementation applications. It will assist the personnel of power companies to implement the aging management activities at different phases of the lifetime of a power plant. It will provide systematic methods for planning, surveillance, inspection, monitoring, condition assessment, maintenance and repair of structures. (authors)

Carbonation of ternary cementitious concrete systems containing fly ash and silica fume

Directory of Open Access Journals (Sweden)

Eehab Ahmed Badreldin Khalil

2015-04-01

Full Text Available Carbonation is quite a complex physical negative effect phenomenon on concrete especially in the ones containing ternary blends of Portland Cement, fly ash, and silica fume. Nine selected concrete mixtures were prepared with various water to cementitious materials’ ratios and various cementitious contents. The concrete mixtures were adapted in such a way to have the same workability and air content. The fresh concrete properties were kept near identical in slump, air content, and unit weight. The variation was in the hardened concrete mechanical properties of compression and tension strength. The carbonation phenomenon was studied for these mixes showing at which mixes of ternary cementitious content heavy carbonation attacks maybe produced. The main components of such mixes that do affect the carbonation process with time were presented.

Design and application of a small size SAFT imaging system for concrete structure

Science.gov (United States)

Shao, Zhixue; Shi, Lihua; Shao, Zhe; Cai, Jian

2011-07-01

A method of ultrasonic imaging detection is presented for quick non-destructive testing (NDT) of concrete structures using synthesized aperture focusing technology (SAFT). A low cost ultrasonic sensor array consisting of 12 market available low frequency ultrasonic transducers is designed and manufactured. A channel compensation method is proposed to improve the consistency of different transducers. The controlling devices for array scan as well as the virtual instrument for SAFT imaging are designed. In the coarse scan mode with the scan step of 50 mm, the system can quickly give an image display of a cross section of 600 mm (L) × 300 mm (D) by one measurement. In the refined scan model, the system can reduce the scan step and give an image display of the same cross section by moving the sensor array several times. Experiments on staircase specimen, concrete slab with embedded target, and building floor with underground pipe line all verify the efficiency of the proposed method.

Fibre Concrete 2017

Science.gov (United States)

2017-09-01

9th international conference on fibre reinforced concretes (FRC), textile reinforced concretes (TRC) and ultra-high performance concretes (UHPC) Preface The Fibre Concrete Conference series is held biennially to provide a platform to share knowledge on fibre reinforced concretes, textile concretes and ultra-high performance concretes regarding material properties and behaviour, technology procedures, topics of long-term behaviour, creep, durability; sustainable aspects of concrete including utilisation of waste materials in concrete production and recycling of concrete. The tradition of Fibre Concrete Conferences started in eighties of the last century. Nowadays the conference is organized by the Department of Concrete and Masonry Structures of the Czech Technical University in Prague, Faculty of Civil Engineering. The 9th International Conference Fibre Concrete 2017 had 109 participants from 27 countries all over the world. 55 papers were presented including keynote lectures of Professor Bažant, Professor Bartoš and Dr. Broukalová. The conference program covered wide range of topics from scientific research to practical applications. The presented contributions related to performance and behaviour of cement based composites, their long-term behaviour and durability, sustainable aspects, advanced analyses of structures from these composites and successful applications. This conference was organized also to honour Professor Zděnek P. Bažant on the occasion of his jubilee and to appreciate his merits and discoveries in the field of fibre reinforced composites, structural mechanics and engineering.

Carbonation and CO2 uptake of concrete

International Nuclear Information System (INIS)

Yang, Keun-Hyeok; Seo, Eun-A; Tae, Sung-Ho

2014-01-01

This study developed a reliable procedure to assess the carbon dioxide (CO 2 ) uptake of concrete by carbonation during the service life of a structure and by the recycling of concrete after demolition. To generalize the amount of absorbable CO 2 per unit volume of concrete, the molar concentration of carbonatable constituents in hardened cement paste was simplified as a function of the unit content of cement, and the degree of hydration of the cement paste was formulated as a function of the water-to-cement ratio. The contribution of the relative humidity, type of finishing material for the concrete surface, and the substitution level of supplementary cementitious materials to the CO 2 diffusion coefficient in concrete was reflected using various correction factors. The following parameters varying with the recycling scenario were also considered: the carbonatable surface area of concrete crusher-runs and underground phenomena of the decreased CO 2 diffusion coefficient and increased CO 2 concentration. Based on the developed procedure, a case study was conducted for an apartment building with a principal wall system and an office building with a Rahmen system, with the aim of examining the CO 2 uptake of each structural element under different exposure environments during the service life and recycling of the building. As input data necessary for the case study, data collected from actual surveys conducted in 2012 in South Korea were used, which included data on the surrounding environments, lifecycle inventory database, life expectancy of structures, and recycling activity scenario. Ultimately, the CO 2 uptake of concrete during a 100-year lifecycle (life expectancy of 40 years and recycling span of 60 years) was estimated to be 15.5%–17% of the CO 2 emissions from concrete production, which roughly corresponds to 18%–21% of the CO 2 emissions from the production of ordinary Portland cement. - Highlights: • CO 2 uptake assessment approach owing to the

Concrete Materials with Ultra-High Damage Resistance and Self- Sensing Capacity for Extended Nuclear Fuel Storage Systems

Energy Technology Data Exchange (ETDEWEB)

Li, Mo [Univ. of California, Irvine, CA (United States); Nakshatrala, Kalyana [Univ. of Houston, TX (United States); William, Kasper [Univ. of Houston, TX (United States); Xi, Yungping [Univ. of Colorado, Boulder, CO (United States)

2017-02-08

The objective of this project is to develop a new class of multifunctional concrete materials (MSCs) for extended spent nuclear fuel (SNF) storage systems, which combine ultra-high damage resistance through strain-hardening behavior with distributed multi-dimensional damage self-sensing capacity. The beauty of multifunctional concrete materials is two-fold: First, it serves as a major material component for the SNF pool, dry cask shielding and foundation pad with greatly improved resistance to cracking, reinforcement corrosion, and other common deterioration mechanisms under service conditions, and prevention from fracture failure under extreme events (e.g. impact, earthquake). This will be achieved by designing multiple levels of protection mechanisms into the material (i.e., ultrahigh ductility that provides thousands of times greater fracture energy than concrete and normal fiber reinforced concrete; intrinsic cracking control, electrochemical properties modification, reduced chemical and radionuclide transport properties, and crack-healing properties). Second, it offers capacity for distributed and direct sensing of cracking, strain, and corrosion wherever the material is located. This will be achieved by establishing the changes in electrical properties due to mechanical and electrochemical stimulus. The project will combine nano-, micro- and composite technologies, computational mechanics, durability characterization, and structural health monitoring methods, to realize new MSCs for very long-term (greater than 120 years) SNF storage systems.

Investigation of early timber–concrete composite bridges in the United States

Science.gov (United States)

James P. Wacker; Alfredo Dias; Travis K. Hosteng

2017-01-01

The use of timber–concrete composite (TCC) bridges in the United States dates back to circa 1925. Two different TCC systems were constructed during this early period. The first system included a longitudinal nail-laminated deck composite with a concrete deck top layer. The second system included sawn timber stringers supporting a concrete deck top layer. Records...

Concrete with onyx waste aggregate as aesthetically valued structural concrete

Science.gov (United States)

Setyowati E., W.; Soehardjono, A.; Wisnumurti

2017-09-01

The utillization of Tulungagung onyx stone waste as an aggregate of concrete mixture will improve the economic value of the concrete due to the brighter color and high aesthetic level of the products. We conducted the research of 75 samples as a test objects to measure the compression stress, splits tensile stress, flexural tensile stress, elasticity modulus, porosity modulus and also studied 15 test objects to identify the concrete micro structures using XRD test, EDAX test and SEM test. The test objects were made from mix designed concrete, having ratio cement : fine aggregate : coarse aggregate ratio = 1 : 1.5 : 2.1, and W/C ratio = 0.4. The 28 days examination results showed that the micro structure of Tulungagung onyx waste concrete is similar with normal concrete. Moreover, the mechanical test results proved that Tulungagung onyx waste concretes also have a qualified level of strength to be used as a structural concrete with higher aesthetic level.

The neutron physics of concrete reflectors

International Nuclear Information System (INIS)

Monahan, S.P.

1995-01-01

It has long been known that concrete reflection can be an important factor in determining the critical state of any fissile system, single unit or storage array. Since there can be a large variation in the chemical makeup of concrete, mass-limit reduction factors are necessarily conservative, and may lead to a very uneconomical storage arrangement. This study was undertaken to clarify the importance of the various concrete constituents and to determine some general guidance as to the magnitude of the reactivity effects for the more likely fissile material storage conditions

Delamination detection in reinforced concrete using thermal inertia

International Nuclear Information System (INIS)

Del Grande, N K; Durbin, P F.

1998-01-01

We investigated the feasibility of thermal inertia mapping for bridge deck inspections. Using pulsed thermal imaging, we heat-stimulated surrogate delaminations in reinforced concrete and asphalt-concrete slabs. Using a dual-band infrared camera system, we measured thermal inertia responses of Styrofoam implants under 5 cm of asphalt, 5 cm of concrete, and 10 cm of asphalt and concrete. We compared thermal maps from solar-heated concrete and asphalt-concrete slabs with thermal inertia maps from flash-heated concrete and asphalt-concrete slabs. Thermal inertia mapping is a tool for visualizing and quantifying subsurface defects. Physically, thermal inertia is a measure of the resistance of the bridge deck to temperature change. Experimentally, it is determined from the inverse slope of the surface temperature versus the inverse square root of time. Mathematically, thermal inertia is the square root of the product of thermal conductivity, density, and heat capacity. Thermal inertia mapping distinguishes delaminated decks which have below-average thermal inertias from normal or shaded decks. Key Words: Pulsed Thermal Imaging, Thermal Inertia, Detection Of Concrete Bridgedeck Delaminations

Pervious Concrete

OpenAIRE

Torsvik, Øyvind André Hoff

2012-01-01

Pervious concrete is a material with a high degree of permeability but generally low strength. The material is primarily used for paving applications but has shown promise in many other areas of usage. This thesis investigates the properties of pervious concrete using normal Norwegian aggregates and practices. An overview of important factors when it comes to designing and producing pervious concrete is the result of this investigation. Several experiments have been performed in the concrete ...

Sustainable Concrete Technology

Directory of Open Access Journals (Sweden)

Sim J.

2015-12-01

Full Text Available The growing concern over global warming and significant ecological changes requires sustainable development in all fields of science and technology. Concrete not only consumes huge amount of energy and natural sources, but also emits large amount of CO2, mainly due to the production of cement. It is evident that such large amount of concrete production has put significant impact on the energy, resource, environment, and ecology of the society. Hence, how to develop the concrete technology in a sustainable way has become a significant issue. In this paper, some of Korean researches for sustainable development of concrete are presented. These are sustainable strengthening for deteriorated concrete structure, sustainable reinforcement of new concrete structure, sustainable concrete using recycled aggregate and supplementary cementing materials and finally application of each technique to precast concrete.

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

International Nuclear Information System (INIS)

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

2014-01-01

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. (paper)

Properties of concrete containing foamed concrete block waste as fine aggregate replacement

Science.gov (United States)

Muthusamy, K.; Budiea, A. M. A.; Zaidan, A. L. F.; Rasid, M. H.; Hazimmah, D. S.

2017-11-01

Environmental degradation due to excessive sand mining dumping at certain places and disposal of foamed concrete block waste from lightweight concrete producing industry are issues that should be resolved for a better and cleaner environment of the community. Thus, the main intention of this study is to investigate the potential of foamed concrete block waste as partial sand replacement in concrete production. The foamed concrete waste (FCW) used in this research that were supplied by a local lightweight concrete producing industry. The workability and compressive strength of concrete containing various percentage of foamed concrete waste as partial sand replacement has been investigated. Prior to the use, the foamed concrete waste were crushed to produce finer particles. Six concrete mixes containing various content of crushed foamed concrete waste that are 0%, 10%, 20%, 30%, 40% and 50% were used in this experimental work. Then the prepared specimens were placed in water curing until the testing age. Compressive strength test and flexural strength tests were conducted at 7, 14 and 28 days. The result shows that integration of crushed foamed concrete waste as partial sand replacement in concrete reduces the mix workability. It is interesting to note that both compressive strength and flexural strength of concrete improves when 30% crushed foamed concrete waste is added as partial sand replacement.

Seismic behavior of fiber reinforced steel-concrete composite systems

OpenAIRE

Faghih, F.; Das, D.; Ayoub, A.

2017-01-01

The addition of Steel Fibers (SF) to concrete has been widely studied in the past decades as a mean to control its crack behavior and maintain its ductility in tension. It has been verified that the use of these fibers at an appropriate dosage can change the behavior of structural members from brittle to ductile. Further, since the discovery of carbon nanotubes/fibers (CNT/CNF), they have been also considered as efficient fibers to be used in construction materials such as concrete. Previous ...

Recycled construction and demolition concrete waste as aggregate for structural concrete

Directory of Open Access Journals (Sweden)

Ashraf M. Wagih

2013-12-01

Full Text Available In major Egyptian cities there is a surge in construction and demolition waste (CDW quantities causing an adverse effect on the environment. The use of such waste as recycled aggregate in concrete can be useful for both environmental and economical aspects in the construction industry. This study discusses the possibility to replace natural coarse aggregate (NA with recycled concrete aggregate (RCA in structural concrete. An investigation into the properties of RCA is made using crushing and grading of concrete rubble collected from different demolition sites and landfill locations around Cairo. Aggregates used in the study were: natural sand, dolomite and crushed concretes obtained from different sources. A total of 50 concrete mixes forming eight groups were cast. Groups were designed to study the effect of recycled coarse aggregates quality/content, cement dosage, use of superplasticizer and silica fume. Tests were carried out for: compressive strength, splitting strength and elastic modulus. The results showed that the concrete rubble could be transformed into useful recycled aggregate and used in concrete production with properties suitable for most structural concrete applications in Egypt. A significant reduction in the properties of recycled aggregate concrete (RAC made of 100% RCA was seen when compared to natural aggregate concrete (NAC, while the properties of RAC made of a blend of 75% NA and 25% RCA showed no significant change in concrete properties.

Performance and working life of cathodic protection systems for concrete structures

NARCIS (Netherlands)

Polder, R.B.; Worm, D.; Courage, W.; Leegwater, G.

2012-01-01

Corrosion of reinforcing steel in concrete structures causes concrete cracking and steel diameter reduction, eventually resulting in loss of safety. Conventional repair means heavy, labour intensive and costly work and the required quality level is under economic pressure. Consequently, conventional

Special protective concretes

International Nuclear Information System (INIS)

Bouniol, P.

2001-01-01

Concrete is the most convenient material when large-scale radiation protection is needed. Thus, special concretes for nuclear purposes are used in various facilities like reactors, reprocessing centers, storage sites, accelerators, hospitals with nuclear medicine equipment, food ionization centers etc.. The recent advances made in civil engineering for the improvement of concrete durability and compactness are for a large part transposable to protection concretes. This article presents the basic knowledge about protection concretes with the associated typological and technological aspects. A large part is devoted to the intrinsic properties of concretes and to their behaviour in irradiation and temperature conditions: 1 - definition and field of application of special protective concretes; 2 - evolution of concepts and technologies (durability of structures, techniques of formulation, new additives, market evolution); 3 - design of protective structures (preliminary study, radiation characteristics, thermal constraints, damping and dimensioning, mechanical criteria); 4 - formulation of special concretes (general principles, granulates, hydraulic binders, pulverulent additives, water/cement ratio, reference composition of some special concretes); 5 - properties of special concretes (damping and thermo-mechanical properties); 6 - induced-irradiation and temperature phenomena (activation, radiolysis, mineralogical transformations, drying, shrinking, creep, corrosion of reinforcement). (J.S.)

Self-Compacting Concrete

OpenAIRE

Okamura, Hajime; Ouchi, Masahiro

2003-01-01

Self-compacting concrete was first developed in 1988 to achieve durable concrete structures. Since then, various investigations have been carried out and this type of concrete has been used in practical structures in Japan, mainly by large construction companies. Investigations for establishing a rational mix-design method and self-compactability testing methods have been carried out from the viewpoint of making self-compacting concrete a standard concrete.

A review on the suitability of rubberized concrete for concrete bridge decks

Science.gov (United States)

Syamir Senin, Mohamad; Shahidan, Shahiron; Radziah Abdullah, Siti; Anting Guntor, Nickholas; Syazani Leman, Alif

2017-11-01

Road authorities manage a large population of ageing bridges, a substantial number of which fail to meet the current requirements either due to deterioration and other structural deficiencies or as a result of the escalating demands imposed by increased traffic. This problem is related to the dynamic load from vehicles. This problem can be solved by producing a type of concrete that can reduce the amplitude of oscillation or vibration such as rubberized concrete. Green construction has been a very important aspect in concrete production field in the last decade. One of the most problematic waste materials is scrap tires. The use of scrap tires in civil engineering is increasing by producing rubberized concrete. Rubberized concrete is a type of concrete that is mixed with rubber. The purpose of this review is to justify the suitability of rubberized concrete for concrete bridge decks. Several parameters named physical, chemical and mechanical properties were measured to ensure the suitability of rubberized concrete for concrete bridge decks. Rubberized concrete has similar workability to normal concrete. The rubber reduced the density and compressive strength of the concrete while increased the flexural strength, water absorption and damping ratio. The used of rubber in concrete beyond 20% is not recommended due to decreasing in compressive strength. Rubberized concrete recommended to be used in circumstances where vibration damping was required such as in bridge construction as shock-wave absorber.

Concreteness effects in semantic processing: ERP evidence supporting dual-coding theory.

Science.gov (United States)

Kounios, J; Holcomb, P J

1994-07-01

Dual-coding theory argues that processing advantages for concrete over abstract (verbal) stimuli result from the operation of 2 systems (i.e., imaginal and verbal) for concrete stimuli, rather than just 1 (for abstract stimuli). These verbal and imaginal systems have been linked with the left and right hemispheres of the brain, respectively. Context-availability theory argues that concreteness effects result from processing differences in a single system. The merits of these theories were investigated by examining the topographic distribution of event-related brain potentials in 2 experiments (lexical decision and concrete-abstract classification). The results were most consistent with dual-coding theory. In particular, different scalp distributions of an N400-like negativity were elicited by concrete and abstract words.

Environmental importance, composition and properties of pervious concrete

Directory of Open Access Journals (Sweden)

Topličić-Ćurčić Gordana

2016-01-01

Full Text Available Porous or pervious concrete was in use since the 60's of the previous century. It was first used in the USA and afterwards in Europe. The environmental importance of pervious concrete can be seen through fast collection of stormwater from the pavements, parking lots and other impervious surfaces. . Special purification systems remove the detrimental matter from the collected strormwater. As such, it can be used for other purposes. The pervious concrete has little or almost no fine aggregates. Its porosity is high, and ranges between 15 and 30 % in comparison to the concrete volume. Prior to massive usage of pervious concrete, it was necessary to prove, i.e. to examine its properties in service conditions. The paper elucidates the environmental character of pervious concrete, provides its usual composition and its properties.

A prestressed concrete pressure vessel for helium high temperature reactor system

International Nuclear Information System (INIS)

Horner, R.M.W.; Hodzic, A.

1976-01-01

A novel prestressed concrete pressure vessel has been developed to provide the primary containment for a fully integrated system comprising a high temperature nuclear reactor, three horizontally mounted helium turbines, associated heat exchangers and inter-connecting ducts. The design and analysis of the pressure vessel is described. Factors affecting the final choice of layout are discussed, and earlier development work seeking to resolve the conflicting requirements of the structural, mechanical, and system engineers outlined. Proposals to increase the present output of about 1000 MW of electrical power to over 3000 MW, by incorporating four turbines in a single pressure vessel are presented. (author)

Concrete Waste as a Cement Replacement Material in Concrete Blocks for Optimization of Thermal and Mechanical Properties

Directory of Open Access Journals (Sweden)

Rosman M.S.

2014-01-01

Full Text Available The sustainability of the natural environment and eco-systems is of great importance. Waste generated from construction forces mankind to find new dumping grounds and at the same time, more natural resources are required for use as construction materials. In order to overcome this problem, this study was conducted to investigate the use of concrete waste in concrete blocks with a special focus on the thermal and mechanical properties of the resulting products. Three varieties of concrete mixtures were prepared, whereby they each contained different amounts of concrete waste of 0%, 5% and 15%, respectively. These mixtures were formed into cube specimens and were then analysed for data on their compressive strength, density and ultrasonic pulse. Thermal investigations were carried out on each admixture as well as on a control concrete block of model design. The thermal data results indicated that the 15% concrete waste mixture had the lowest temperature in comparison to the surrounding air. For density and compressive strength, the highest readings came from the control mixture at 2390 kg/m3 and 40.69 N/mm2, respectively, at 28 days. In terms of pulse velocity, the 5% concrete waste mixture indicated medium quality results of 4016 m/s.

Hybrid FRP-concrete bridge deck system final report II : long term performance of hybrid FRP-concrete bridge deck system.

Science.gov (United States)

2009-06-01

This report describes the investigation of the long term structural performance of a : hybrid FRP-concrete (HFRPC) bridge deck on steel girders. The study aimed at : assessing three long term aspects pertaining to the HFRPC bridge deck: (1) creep : c...

Monitoring of Concrete Structures Using Ofdr Technique

Science.gov (United States)

Henault, J. M.; Salin, J.; Moreau, G.; Delepine-Lesoille, S.; Bertand, J.; Taillade, F.; Quiertant, M.; Benzarti, K.

2011-06-01

Structural health monitoring is a key factor in life cycle management of infrastructures. Truly distributed fiber optic sensors are able to provide relevant information on large structures, such as bridges, dikes, nuclear power plants or nuclear waste disposal facilities. The sensing chain includes an optoelectronic unit and a sensing cable made of one or more optical fibers. A new instrument based on Optical Frequency Domain Reflectometry (OFDR), enables to perform temperature and strain measurements with a centimeter scale spatial resolution over hundred of meters and with a level of precision equal to 1 μstrain and 0.1 °C. Several sensing cables are designed with different materials targeting to last for decades in a concrete aggressive environment and to ensure an optimal transfer of temperature and strain from the concrete matrix to the optical fiber. Tests were carried out by embedding various sensing cables into plain concrete specimens and representative-scale reinforced concrete structural elements. Measurements were performed with an OFDR instrument; meanwhile, mechanical solicitations were imposed to the concrete element. Preliminary experiments are very promising since measurements performed with distributed sensing system are comparable to values obtained with conventional sensors used in civil engineering and with the Strength of Materials Modelling. Moreover, the distributed sensing system makes it possible to detect and localize cracks appearing in concrete during the mechanical loading.

A 3D Lattice Modelling Study of Drying Shrinkage Damage in Concrete Repair Systems

NARCIS (Netherlands)

Lukovic, M.; Savija, B.; Schlangen, H.E.J.G.; Ye, G.; van Breugel, K.

2016-01-01

Differential shrinkage between repair material and concrete substrate is considered to be the main cause of premature failure of repair systems. The magnitude of induced stresses depends on many factors, for example the degree of restraint, moisture gradients caused by curing and drying conditions,

A 3D Lattice Modelling Study of Drying Shrinkage Damage in Concrete Repair Systems

Directory of Open Access Journals (Sweden)

Mladena Luković

2016-07-01

Full Text Available Differential shrinkage between repair material and concrete substrate is considered to be the main cause of premature failure of repair systems. The magnitude of induced stresses depends on many factors, for example the degree of restraint, moisture gradients caused by curing and drying conditions, type of repair material, etc. Numerical simulations combined with experimental observations can be of great use when determining the influence of these parameters on the performance of repair systems. In this work, a lattice type model was used to simulate first the moisture transport inside a repair system and then the resulting damage as a function of time. 3D simulations were performed, and damage patterns were qualitatively verified with experimental results and cracking tendencies in different brittle and ductile materials. The influence of substrate surface preparation, bond strength between the two materials, and thickness of the repair material were investigated. Benefits of using a specially tailored fibre reinforced material, namely strain hardening cementitious composite (SHCC, for controlling the damage development due to drying shrinkage in concrete repairs was also examined.

Porous Structure of Road Concrete

OpenAIRE

Пшембаев, М. К.; Гиринский, В. В.; Ковалев, Я. Н.; Яглов, В. Н.; Будниченко, С. С.

2016-01-01

Having a great number of concrete structure classifications it is recommended to specify the following three principal types: microstructure – cement stone structure; mesostructure – structure of cement-sand mortar in concrete; macrostucture – two-component system that consists of mortar and coarse aggregate. Every mentioned-above structure has its own specific features which are related to the conditions of their formation. Thus, microstructure of cement stone can be characterized by such st...

Evaluation of ilmenite serpentine concrete and ordinary concrete as nuclear reactor shielding

International Nuclear Information System (INIS)

Abulfaraj, W.H.; Kamal, S.M.

1994-01-01

The present study involves adapting a formal decision methodology to the selection of alternative nuclear reactor concrete shielding. Multiattribute utility theory is selected to accommodate decision maker's preferences. Multiattribute utility theory (MAU) is here employed to evaluate two appropriate nuclear reactor shielding concretes in terms of effectiveness to determine the optimal choice in order to meet the radiation protection regulations. These concretes are Ordinary concrete (O.C.) and Illmenite Serpentile concrete (I.S.C.). These are normal weight concrete and heavy weight heat resistive concrete, respectively. The effectiveness objective of the nuclear reactor shielding is defined and structured into definite attributes and subattributes to evaluate the best alternative. Factors affecting the decision are dose received by reactor's workers, the material properties as well as cost of concrete shield. A computer program is employed to assist in performing utility analysis. Based upon data, the result shows the superiority of Ordinary concrete over Illmenite Serpentine concrete. (Author)

Study of strength kinetics of sand concrete system of accelerated hardening

Science.gov (United States)

Sharanova, A. V.; Lenkova, D. A.; Panfilova, A. D.

2018-04-01

Methods of calorimetric analysis are used to study the dynamics of the hydration processes of concretes with different accelerator contents. The efficiency of the isothermal calorimetry method is shown for study of strength kinetics of concrete mixtures of accelerated hardening, promising for additive technologies in civil engineering.

Towards Better Understanding of Concrete Containing Recycled Concrete Aggregate

Directory of Open Access Journals (Sweden)

Hisham Qasrawi

2013-01-01

Full Text Available The effect of using recycled concrete aggregates (RCA on the basic properties of normal concrete is studied. First, recycled aggregate properties have been determined and compared to those of normal aggregates. Except for absorption, there was not a significant difference between the two. Later, recycled aggregates were introduced in concrete mixes. In these mixes, natural coarse aggregate was partly or totally replaced by recycled aggregates. Results show that the use of recycled aggregates has an adverse effect on the workability and air content of fresh concrete. Depending on the water/cement ratio and on the percent of the normal aggregate replaced by RCA, the concrete strength is reduced by 5% to 25%, while the tensile strength is reduced by 4% to 14%. All results are compared with previous research. As new in this research, the paper introduces a simple formula for the prediction of the modulus of elasticity of RCA concrete. Furthermore, the paper shows the variation of the air content of RAC.

Vision-Inspection System for Residue Monitoring of Ready-Mixed Concrete Trucks

Directory of Open Access Journals (Sweden)

Deok-Seok Seo

2015-01-01

Full Text Available The objective of this study is to propose a vision-inspection system that improves the quality management for ready-mixed concrete (RMC. The proposed system can serve as an alternative to the current visual inspection method for the detection of residues in agitator drum of RMC truck. To propose the system, concept development and the system-level design should be executed. The design considerations of the system are derived from the hardware properties of RMC truck and the conditions of RMC factory, and then 6 major components of the system are selected in the stage of system level design. The prototype of system was applied to a real RMC plant and tested for verification of its utility and efficiency. It is expected that the proposed system can be employed as a practical means to increase the efficiency of quality management for RMC.

Evaluation of recycled concrete as aggregate in new concrete pavements.

Science.gov (United States)

2014-04-01

This study evaluated the use of recycled concrete as coarse aggregate in new concrete pavements. : Recycled concrete aggregate (RCA) produced from demolished pavements in three geographically dispersed locations in Washington state were used to perfo...

A new concept for the targeted cutting of concrete structures

International Nuclear Information System (INIS)

Reinhardt, Steffen; Gentes, Sascha; Weidemann, Roman; Geimer, Marcus

2011-01-01

The decontamination and crushing of reinforced concrete is a main part during deconstruction of nuclear facilities. The selective treatment of contaminated or activated material is of special interest, since the non-contaminated material can be transferred into the normal reprocessing cycle. In the frame of a project concerning the innovative cutting of massive reinforced concrete structures an all-purpose system for spatially restricted and defined cutting of strongly reinforced concrete including packaging suitable for final disposal was developed. Due to the remote handling of the machine the dose rate for personnel can be reduced significantly. Main part of the system is the tool that can cut highly reinforced concrete without system or component replacement. The authors describe preliminary tests of these tools, further experiments and process optimization are necessary before the tools can be integrated into the new system.

TRANSPORT THROUGH CRACKED CONCRETE: LITERATURE REVIEW

Energy Technology Data Exchange (ETDEWEB)

Langton, C.

2012-05-11

Concrete containment structures and cement-based fills and waste forms are used at the Savannah River Site to enhance the performance of shallow land disposal systems designed for containment of low-level radioactive waste. Understanding and measuring transport through cracked concrete is important for describing the initial condition of radioactive waste containment structures at the Savannah River Site (SRS) and for predicting performance of these structures over time. This report transmits the results of a literature review on transport through cracked concrete which was performed by Professor Jason Weiss, Purdue University per SRR0000678 (RFP-RQ00001029-WY). This review complements the NRC-sponsored literature review and assessment of factors relevant to performance of grouted systems for radioactive waste disposal. This review was performed by The Center for Nuclear Waste Regulatory Analyses, San Antonio, TX, and The University of Aberdeen, Aberdeen Scotland and was focused on tank closure. The objective of the literature review on transport through cracked concrete was to identify information in the open literature which can be applied to SRS transport models for cementitious containment structures, fills, and waste forms. In addition, the literature review was intended to: (1) Provide a framework for describing and classifying cracks in containment structures and cementitious materials used in radioactive waste disposal, (2) Document the state of knowledge and research related to transport through cracks in concrete for various exposure conditions, (3) Provide information or methodology for answering several specific questions related to cracking and transport in concrete, and (4) Provide information that can be used to design experiments on transport through cracked samples and actual structures.

Transport Through Cracked Concrete: Literature Review

International Nuclear Information System (INIS)

Langton, C.

2012-01-01

Concrete containment structures and cement-based fills and waste forms are used at the Savannah River Site to enhance the performance of shallow land disposal systems designed for containment of low-level radioactive waste. Understanding and measuring transport through cracked concrete is important for describing the initial condition of radioactive waste containment structures at the Savannah River Site (SRS) and for predicting performance of these structures over time. This report transmits the results of a literature review on transport through cracked concrete which was performed by Professor Jason Weiss, Purdue University per SRR0000678 (RFP-RQ00001029-WY). This review complements the NRC-sponsored literature review and assessment of factors relevant to performance of grouted systems for radioactive waste disposal. This review was performed by The Center for Nuclear Waste Regulatory Analyses, San Antonio, TX, and The University of Aberdeen, Aberdeen Scotland and was focused on tank closure. The objective of the literature review on transport through cracked concrete was to identify information in the open literature which can be applied to SRS transport models for cementitious containment structures, fills, and waste forms. In addition, the literature review was intended to: (1) Provide a framework for describing and classifying cracks in containment structures and cementitious materials used in radioactive waste disposal, (2) Document the state of knowledge and research related to transport through cracks in concrete for various exposure conditions, (3) Provide information or methodology for answering several specific questions related to cracking and transport in concrete, and (4) Provide information that can be used to design experiments on transport through cracked samples and actual structures.

Removal of contaminated concrete surfaces by microwave heating: Phase 1 results

International Nuclear Information System (INIS)

White, T.L.; Grubb, R.G.; Pugh, L.P.; Foster, D. Jr.; Box, W.D.

1992-01-01

Oak Ridge National Laboratory (ORNL) is developing a microwave heating process to remove radiologically contaminated surface layers from concrete. The microwave energy is directed at the concrete surface and heats the concrete and free water present in the concrete matrix. Continued heating produces steam-pressure-induced mechanical stresses that cause the concrete surface to burst. The concrete particles from this steam explosion are small enough to be removed by a vacuum system, yet less than 1% of the debris is small enough to pose an airborne contamination hazard. The first phase of this program has demonstrated reliable removal of noncontaminated concrete surfaces at frequencies of 2.45 GHz and 10.6 GHz. Continuous concrete removal rates of 1.07 cm 3 /s with 5.2 kW of 2.45.-GHz power and 2.11 cm 3 /s with 3.6 kW of 10.6-GHz power have been demonstrated. Figures-of-merit for microwave removal of concrete have been calculated to be 0.21 cm 3 /s/kW at 2.45 GHz and 0.59 cm 3 /s/kW at 10.6 GHz. The amount of concrete removed in a single pass can be controlled by choosing the frequency and power of the microwave system

Recycled concrete aggregate in portland cement concrete.

Science.gov (United States)

2013-01-01

Aggregates can be produced by crushing hydraulic cement concrete and are known as recycled concrete : aggregates (RCA). This report provides results from a New Jersey Department of Transportation study to identify : barriers to the use of RCA in new ...

Design of a 3-D Magnetic Mapping System to Locate Reinforcing Steel in Concrete Pavements

Science.gov (United States)

2017-12-01

This report outlines the design, fabrication, and testing of a 3-D magnetic mapping system used to locate reinforcing steel in concrete pavements developed at Kansas State University (KSU) in 2006. The magnetic sensing functionality is based on the p...

Analysis of Possibilities for Using Recycled Concrete Aggregate in Concrete Pavement

OpenAIRE

R. Pernicova; D. Dobias

2016-01-01

The present article describes the limits of using recycled concrete aggregate (denoted as RCA) in the top layer of concrete roads. The main aim of this work is to investigate the possibility of reuse of recycled aggregates obtained by crushing the old concrete roads as a building material in the new top layers of concrete pavements. The paper is based on gathering the current knowledge about how to use recycled concrete aggregate, suitability, and modification of the properties and its standa...

Experimental investigations concerning the suitability of channel systems for liner leak detection and drainage of a prestressed concrete vessel

International Nuclear Information System (INIS)

Nickel, M.; Breitbach, G.; Altes, J.; Escherich, K.H.; Wolters, J.

1985-02-01

The iternal surfaces of prestressed concrete pressure vessels are fitted with a steel liner to preserve the gas tightness of the primary circuit. Because of the high quality manufacture and the loading conditions a linear failure can be practically excluded. However, if it is hypothetically assumed, that a leak develops during reactor operation, it may be difficult to determine the position of the leak, because the linear area is very large. For tightness surveillance and for venting channel systems installed in close proximity to the linear are suitable. The suitability of such channels for leak detection, localisation and venting was investigated experimentally. A concrete wall (length 2.5 m, height 2.0 m, thickness 0.5 m) was constructed, covered on one side with a steel liner. Behind the liner two different channel systems have been installed. For the simulation of leaks holes were drilled into the liner. The experimental programm contained the following measurements: determination of gas flow rates into the different leaks, distribution of leakage gas over the array of channels and determination of pressures into the concrete and immediately behind the liner. The experiments have shown, that channel arrays immediately adjacent to the liner are the most suitable systems for localisation and controlled exhaust of leakage gas. The suitability decreases, if the channels are set into the concrete somewhat distant from the liner. (orig.) [de

Life Cycle Cost Analysis of Ready Mix Concrete Plant

Science.gov (United States)

Topkar, V. M.; Duggar, A. R.; Kumar, A.; Bonde, P. P.; Girwalkar, R. S.; Gade, S. B.

2013-11-01

India, being a developing nation is experiencing major growth in its infrastructural sector. Concrete is the major component in construction. The requirement of good quality of concrete in large quantities can be fulfilled by ready mix concrete batching and mixing plants. The paper presents a technique of applying the value engineering tool life cycle cost analysis to a ready mix concrete plant. This will help an investor or an organization to take investment decisions regarding a ready mix concrete facility. No economic alternatives are compared in this study. A cost breakdown structure is prepared for the ready mix concrete plant. A market survey has been conducted to collect realistic costs for the ready mix concrete facility. The study establishes the cash flow for the ready mix concrete facility helpful in investment and capital generation related decisions. Transit mixers form an important component of the facility and are included in the calculations. A fleet size for transit mixers has been assumed for this purpose. The life cycle cost has been calculated for the system of the ready mix concrete plant and transit mixers.

Ageing management of CANDUtm concrete containment buildings

International Nuclear Information System (INIS)

Philipose, K.E.; Gregor, F.E.

2009-01-01

The containment system in a Nuclear Power Plant (NPP) provides the final physical barrier against release of radioactive materials to the external environment. Even though there are different physical configurations to meet this fundamental safety function in various reactor types, a common feature is the use of a thick-walled concrete structure as part of the containment system commonly referred to as 'Concrete Containment Building'. In order for the concrete containment buildings to continue to provide the required safety function, it has to maintain its structural integrity. As well, its leak rates under test pressures must be maintained below acceptable limits. As some of the containment buildings of the CANDU nuclear power plants are approaching their fourth decade of successful operation, questions regarding the impact of ageing on their ultimate useful service life emerge. Ageing Management has become the tool for addressing those questions. In this paper, the ageing and ageing management of the CANDU concrete containments are discussed, including the specific programs being implemented to monitor and trend the ageing conditions. Specifically, the usefulness of the embedded strain gauges as a tool for the assessment of the condition of the containment concrete structure is discussed. Some of the operational and test data accumulated over the last 30 years have been evaluated and trended to provide some results and conclusions regarding the satisfactory long-term behaviour of the concrete containment buildings. (authors)

Elastic Composite, Reinforced Lightweight Concrete as a Type of Resilient Composite Systems

OpenAIRE

Esmaeili, Kamyar

2015-01-01

. A kind of "Elastic Composite, Reinforced Lightweight Concrete (ECRLC)" with the mentioned specifics is a type of "Resilient Composite Systems (RCS)" in which, contrary to the basic geometrical assumption of flexure theory in Solid Mechanics, "the strain changes in the beam height during bending" is typically "Non-linear". . Through employing this integrated structure, with significant high strain capability and modulus of resilience in bending, we could constructively achieve high bearing c...

Use of fiber reinforced concrete for concrete pavement slab replacement.

Science.gov (United States)

2014-03-01

Unlike ordinary concrete pavement, replacement concrete slabs need to be open to traffic within 24 hours (sooner in : some cases). Thus, high early-strength concrete is used; however, it frequently cracks prematurely as a result of high : heat of hyd...

Review of constitutive models and failure criteria for concrete

Energy Technology Data Exchange (ETDEWEB)

Seo, Jeong Moon; Choun, Young Sun [Korea Atomic Energy Research Institute, Taejeon (Korea)

2000-03-01

The general behavior, constitutive models, and failure criteria of concrete are reviewed. The current constitutive models for concrete cannot satisfy all of mechanical behavior of concrete. Among several constitutive models, damage models are recommended to describe properly the structural behavior of concrete containment buildings, because failure modes and post-failure behavior are important in containment buildings. A constitutive model which can describe the concrete behavior in tension is required because the containment buildings will reach failure state due to ultimate internal pressure. Therefore, a thorough study on the behavior and models under tension stress state in concrete and reinforced concrete has to be performed. There are two types of failure criteria in containment buildings: structural failure criteria and leakage failure criteria. For reinforced or prestressed concrete containment buildings, concrete cracking does not mean the structural failure of containment building because the reinforcement or post-tensioning system is able to resist tensile stress up to yield stress. Therefore leakage failure criteria will be prior to structural failure criteria, and a strain failure criterion for concrete has to be established. 120 refs., 59 figs., 1 tabs. (Author)

304 Concretion facility closure plan

International Nuclear Information System (INIS)

1990-04-01

The Hanford Site, located northwest of Richland, Washington, houses reactors, chemical-separation systems, and related facilities used for the production of special nuclear materials. The 300 Area of the Hanford Site contains reactor fuel manufacturing facilities and several research and development laboratories. Recyclable scrap uranium Zircaloy-2 and copper silicon alloy, uranium-titanium alloy, beryllium/Zircaloy-2 alloy, and Zircaloy-2 chips and fines were secured in concrete billets in the 304 Concretion Facility, located in the 300 Area. The beryllium/Zircaloy-2 alloy and Zircaloy-2 chips and fines are designated as low-level radioactive mixed waste (LLRMW) with the characteristic of ignitability. The concretion process reduced the ignitability of the fines and chips for safe storage and shipment. This process has been discontinued and the 304 Concretion Facility is now undergoing closure as defined in the Resource Conservation and Recovery Act of 1976 (RCRA). This closure plan presents a description of the facility, the history of materials and wastes managed, and the procedures that will be followed to close the 304 Concretion Facility (304 Facility). Clean closure of the 304 Facility is the proposed method for closure of the facility. Justification for this proposal is presented. 15 refs., 22 figs., 4 tabs

The Bullwhip Effect: Concretization of Entropic Information Dissipation in Supply Chain Systems

Directory of Open Access Journals (Sweden)

Tarik Saikouk

2012-08-01

Full Text Available Supply chains represent complex and dynamic systems that incorporate autonomous firms interacting with one another to fulfill a common goal, while insuring their own ones. These firms’ behaviors are considered to be non-linear and sometimes unpredictable. This makes information transfer in the supply chain complex and causes instability when information transferred is incomplete or incorrect. This instability is characterized by the Bullwhip Effect that represents concretization of entropy, namely the degree of disorder within a system. In this paper we develop a new analytical approach assuming that the bullwhip effect is a consequence of the entropy of the supply chain system that is represented by information dissipation.

A multifunctional design approach for sustainable concrete : with application to concrete mass products

NARCIS (Netherlands)

Hüsken, G.

2010-01-01

This thesis provides a multifunctional design approach for sustainable concrete, particularly earth-moist concrete (EMC), with application to concrete mass products. EMC is a concrete with low water content and stiff consistency that is used for the production of concrete mass products, such as

The influence of recycled concrete aggregates in pervious concrete

Directory of Open Access Journals (Sweden)

L. M. TAVARES

Full Text Available The expansion of urban areas under constant changes in the hydrological cycle directly affects the drainage of rainwater. The problems of urban drainage become major engineering problems to be solved in order to avoid negative consequences for local populations. Another urban problem is the excessive production of construction and demolition waste (CDW, in which , even with a increasingly policy of waste management , have been an end up being thrown in inappropriate disposal sites. Alternatively aiming to a minimization of the problems presented, we propose the study of permeable concrete using recycled concrete aggregate. In this study, there were evaluated the performance of concrete by means of permeability, consistency, strength, and interface conditions of the materials . Satisfactory relationships of resistance/permeability of concrete with recycled aggregate in relation to the concrete with natural aggregates was obtained, showing their best potential.

Possible options for reducing occupational dose from the TMI-2 basement

International Nuclear Information System (INIS)

Munson, L.F.; Harty, R.

1985-11-01

The major sources of exposure in the basement include the enclosed stairwell/elevator shaft structure, water and sludge in the elevator shaft, cast concrete walls, concrete floor slab, water and sludge on the floor, and activity in the paint and loose surface contamination. The sources were identified using data obtained by the utility from water processing, water and solid samples, remote video inspections and radiation monitoring with a robot, and strings of thermoluminescent dosimeters lowered from upper elevations. The area dose rates in the basement range from approximately 4 R/hr (in the NE quadrant) to over 1100 R/hr (near the enclosed stairwell/elevator shaft structure). It is estimated that the basement contains between 11,000 and 21,000 curies of 137 Cs. Specific decontamination and cleanup techniques are discussed. These techniques include flushing with water, high-pressure water blasting, leaching, scabbling and chemical cleaning. The applicability of these techniques to the major sources of radiation are discussed, and possible approaches and work sequences for basement cleanup are given

Mechanical properties of refractory concretes for boilers; Propriedades mecanicas de concretos refratarios para caldeiras

Energy Technology Data Exchange (ETDEWEB)

Angioletto, E.; Pelisser, F.; Peterson, M.; Angioletto, E.; Rocha, M.R.; Arnt, A.B.C. [Universidade do Estado de Santa Catarina (UDESC), Criciuma, SC (Brazil)], E-mail: ean@unesc.net; Coelho, R. [Tractebel Energia, Florianpolis, SC (Brazil)

2010-07-01

Refractory concretes are used in extremely physically demanding conditions. An important example is concretes used as sealing systems in boilers, where their dimensional stability at high temperatures is fundamental to durability and has a strong impact on maintenance costs and system idleness. In this work, refractory concretes with different compositions were characterized and then tested by dilatometry, for compressive strength and in assays involving adherence between tensile concrete/metal inserts, simulating the fixing system in boilers. Analysis of the results showed that refractory concretes do not present retraction due to air during drying, eliminating the possibility of cracking. While casting the plate/prototype with metal inserts, satisfactory concrete/metal adherence was verified and surface cracking occurred that did not influence the tensile bond strength between the insert and the concrete. (author)

Dynamic behavior of radiant cooling system based on capillary tubes in walls made of high performance concrete

DEFF Research Database (Denmark)

Mikeska, Tomás; Svendsen, Svend

2015-01-01

elements made of high performance concrete. The influence of the radiant cooling system on the indoor climate of the test room in terms of the air, surface and operative temperatures and velocities was investigated.The results show that the temperature of the room air can be kept in a comfortable range...... using cooling water for the radiant cooling system with a temperature only about 4K lower than the temperature of the room air. The relatively high speed reaction of the designed system is a result of the slim construction of the sandwich wall elements made of high performance concrete. (C) 2015...... the small amount of fresh air required by standards to provide a healthy indoor environment.This paper reports on experimental analyses evaluating the dynamic behavior of a test room equipped with a radiant cooling system composed of plastic capillary tubes integrated into the inner layer of sandwich wall...

The management routes for materials produced by the dismantling of the BR3-PWR reactor

International Nuclear Information System (INIS)

Klein, M.; Demeulemeester, Y.; Ponnet, M.; Emond, M.; Emond, O.; Dadoumont, J.; Massaut, V.

2000-01-01

The dismantling of the BR3 reactor produces quite large masses of contaminated materials, mainly metals or concrete. The main management routes are: conditioning of the radioactive wastes and disposal, recycling of radioactive materials in the nuclear sector and the recycling of free released materials in the industrial sector or their evacuation as industrial waste. The conditioning of the radioactive wastes is essentially performed in the installations of Belgoprocess and must follow the specifications imposed by the national radwaste management agency ONDRAF/NIRAS. The conditioning of the pieces produced during the cutting of the reactor pressure vessel is given as example. The recycling of radioactive materials in the nuclear sector is possible for metals and for concrete. For metals, SCK.CEN has an agreement with a nuclear foundry which reuses these materials for the fabrication of shieldings. For concrete, an R and D programme is going on with the objective to demonstrate the possible reuse of baryte concrete as raw materials for the production of mortar used in the conditioning of radioactive wastes. The free release of radioactive materials and their reuse or evacuation as radioactive wastes requires the strict respect of procedures and the use of low level measurement techniques. Various decontamination techniques are used at SCK.CEN to reach this objective. For the metals, we use mainly simple washing, abrasive decontamination and hard chemical decontamination. For concrete, we use mainly scabbling or shaving techniques. (authors)

Automatic Control of the Concrete Mixture Homogeneity in Cycling Mixers

Science.gov (United States)

Anatoly Fedorovich, Tikhonov; Drozdov, Anatoly

2018-03-01

The article describes the factors affecting the concrete mixture quality related to the moisture content of aggregates, since the effectiveness of the concrete mixture production is largely determined by the availability of quality management tools at all stages of the technological process. It is established that the unaccounted moisture of aggregates adversely affects the concrete mixture homogeneity and, accordingly, the strength of building structures. A new control method and the automatic control system of the concrete mixture homogeneity in the technological process of mixing components have been proposed, since the tasks of providing a concrete mixture are performed by the automatic control system of processing kneading-and-mixing machinery with operational automatic control of homogeneity. Theoretical underpinnings of the control of the mixture homogeneity are presented, which are related to a change in the frequency of vibrodynamic vibrations of the mixer body. The structure of the technical means of the automatic control system for regulating the supply of water is determined depending on the change in the concrete mixture homogeneity during the continuous mixing of components. The following technical means for establishing automatic control have been chosen: vibro-acoustic sensors, remote terminal units, electropneumatic control actuators, etc. To identify the quality indicator of automatic control, the system offers a structure flowchart with transfer functions that determine the ACS operation in transient dynamic mode.

Improved concrete properties to resist the saline water using environmental by-product

Directory of Open Access Journals (Sweden)

Mohamed Anwar

2013-10-01

Full Text Available This paper investigates the influence of using environmental by-product materials (silica fume and fly ash in concrete on the chloride ion permeability of concrete. Nine concrete mixtures were designed to have the same degree of workability and air content with water/cementitious material ratio of 0.4. The studied parameters include the main fresh and hardened concrete properties such as slump, air content, unit weight, compressive strength, tensile strength, flexural strength, static Young's modulus, and dynamic elastic modulus. Concrete samples were kept in water for 28 days, then immersed in artificial sea water for 5 months. The total and soluble chloride contents were measured through the concrete using the potentiometric titration analysis. The obtained test results indicated that the use of ternary systems in concrete improved the different characteristics of the product concrete and showed a significant resistance to chloride penetration. The weights of chloride in mix 9 (10% silica fume and 25% fly ash at depths from the concrete surface to 30 mm were less than the weights of control mix 1 (100% ordinary Portland cement by about 60%. Further, the ternary systems can be used in concrete industry with considerable proportions.

Influence of Concrete Properties on Molten Core-Concrete Interaction: A Simulation Study

Directory of Open Access Journals (Sweden)

Jin-yang Jiang

2016-01-01

Full Text Available In a severe nuclear power plant accident, the molten core can be released into the reactor pit and interact with sacrificial concrete. In this paper, a simulation study is presented that aims to address the influence of sacrificial concrete properties on molten core-concrete interaction (MCCI. In particular, based on the MELCOR Code, the ferrosiliceous concrete used in European Pressurized Water Reactor (EPR is taken into account with respect to the different ablation enthalpy and Fe2O3 and H2O contents. Results indicate that the concrete ablation rate as well as the hydrogen generation rate depends much on the concrete ablation enthalpy and Fe2O3 and H2O contents. In practice, the ablation enthalpy of sacrificial concrete is the higher the better, while the Fe2O3 and H2O content of sacrificial concrete is the lower the better.

Design, development, and application of precast and prestressed concrete system for rigid pavement in Indonesia

Science.gov (United States)

Nurjaman, Hari; Faizal, Lutfi; Suaryana, Nyoman; Hariandja, Binsar; Gambiro, Purnomo, Wicaksono, Siswo

2017-11-01

The performance of highways in Indonesia until today is yet to be optimum. Flexible or rigid pavement construction generally do not reach designed service lives, either due to the fact that the construction do not meet specifications or unavoidable excessive load. Precast and prestressed concrete system has been applied since 2007, but unfortunately the application has not been optimum due to the fact that the construction method is not integrally carried out. This paper deals with a construction concept that developed in 2015-2017. The concept applies green construction based on integrated manufacture industry, starting from design, construction, function, maintenance and demolition. The concept is applied on the three highway sub-layers, i.e., sub grade, sub base, and surface, and drainage system. Sub grade improvement may use soil dislocation, chemical improvement or concrete matress. Sub base material uses foam mortar, which is material easy in quality control compared to conventional materials. Pavement material uses precast and prestressed concrete components with controlled quality, quickly function as flexible pavement, and moreover, may anticipate excessive loadings. Cost estimation is carried out integrated by life cycle cost: initial investment, obstruction while construction, and maintenance cost during operation. This innovation has passed tests in technical construction method aspects as well as construction work in 2015-2017, so it is available to support infrastructure construction acceleration which achieves quality demanded to date.

TYPES OF STEEL AND CONCRETE COMPOSITE CABLE SPACE FRAMES

Directory of Open Access Journals (Sweden)

G. M. Gasii

2016-12-01

Full Text Available Purpose. Modern terms of the construction generate the need to find new structures, including roof systems that would meet modern requirements. An important aspect in finding constructive solutions for new structures is the use of reliable and advanced materials. Considering this, the decision to develop the new space structures to a wide implementation in practice of domestic and foreign construction are relevant and perspective direction of building structures development. Methodology. Given the results of previously conducted theoretical research of existing types of space roof structures find promising areas of improvement or creation of new structures that should be devoid of weaknesses and imperfections of analogs and they should have an economic effect through rational use of materials. Findings. Types of steel and concrete composite cable space frames and structural features of its elements are developed and considered. The steel and concrete composite cable space frame is a completely new kind of space structure system that has the original structural concept and it was designed to cover large-span industrial and public buildings. The basic elements of that structure system are modular element of the bottom chord and space steel and concrete composite module that consists of tubular rods and reinforced concrete slab. All modular elements are made in the factory. With bottom chord modular elements and space steel and concrete composite modules can be assembled three types of longitudinal elements. It is the beam element, arched element and hanging element. Also with the modules can be assembled various structure system and their combinations. Number of space steel and concrete composite modules and bottom chord modular elements, which is needed to collect steel and concrete composite cable space frames, is determined by calculation and optimal designing. Recommended dimensions of the modular elements of the steel and concrete composite

Electrically conductive Portland cement concrete.

Science.gov (United States)

1986-01-01

There is a need for an effective, simple-to-install secondary anode system for use in the cathodic protection of reinforced concrete bridge decks. In pursuit of such a system, carbon fibers and carbon black were incorporated in portland cement concre...

Microbial healing of cracks in concrete: a review.

Science.gov (United States)

Joshi, Sumit; Goyal, Shweta; Mukherjee, Abhijit; Reddy, M Sudhakara

2017-11-01

Concrete is the most widely used construction material of the world and maintaining concrete structures from premature deterioration is proving to be a great challenge. Early age formation of micro-cracking in concrete structure severely affects the serviceability leading to high cost of maintenance. Apart from conventional methods of repairing cracks with sealants or treating the concrete with adhesive chemicals to prevent the cracks from widening, a microbial crack-healing approach has shown promising results. The unique feature of the microbial system is that it enables self-healing of concrete. The effectiveness of microbially induced calcium carbonate precipitation (MICCP) in improving durability of cementitious building materials, restoration of stone monuments and soil bioclogging is discussed. Main emphasis has been laid on the potential of bacteria-based crack repair in concrete structure and the applications of different bacterial treatments to self-healing cracks. Furthermore, recommendations to employ the MICCP technology at commercial scale and reduction in the cost of application are provided in this review.

SUSTAINABLE CONCRETE FOR WIND TURBINE FOUNDATIONS.

Energy Technology Data Exchange (ETDEWEB)

BERNDT,M.L.

2004-06-01

The use of wind power to generate electricity continues to grow, especially given commitments by various countries throughout the world to ensure that a significant percentage of energy comes from renewable sources. In order to meet such objectives, increasingly larger turbines with higher capacity are being developed. The engineering aspects of larger turbine development tend to focus on design and materials for blades and towers. However, foundations are also a critical component of large wind turbines and represent a significant cost of wind energy projects. Ongoing wind research at BNL is examining two areas: (a) structural response analysis of wind turbine-tower-foundation systems and (b) materials engineering of foundations. This work is investigating the dynamic interactions in wind turbine systems, which in turn assists the wind industry in achieving improved reliability and more cost efficient foundation designs. The results reported herein cover initial studies of concrete mix designs for large wind turbine foundations and how these may be tailored to reduce cost and incorporate sustainability and life cycle concepts. The approach taken was to investigate material substitutions so that the environmental, energy and CO{sub 2}-impact of concrete could be reduced. The use of high volumes of ''waste'' materials in concrete was examined. These materials included fly ash, blast furnace slag and recycled concrete aggregate. In addition, the use of steel fiber reinforcement as a means to improve mechanical properties and potentially reduce the amount of bar reinforcement in concrete foundations was studied. Four basic mixes were considered. These were: (1) conventional mix with no material substitutions, (2) 50% replacement of cement with fly ash, (3) 50% replacement of cement with blast furnace slag and (4) 25% replacement of cement with fly ash and 25% replacement with blast furnace slag. Variations on these mixes included the addition of 1

Development of a concrete placement device for support of abandoned mines

International Nuclear Information System (INIS)

Burnett, M.; Burnett, J.M.; El-Korchi, T.

1994-01-01

Burnett Associates, Inc. (BAI), under contract to the US Bureau of Mines, has developed a reliable and cost effective method of remote placement of point support columns in abandoned mines through boreholes to provide local support, especially under surface structures in subsidence prone areas. The development of the system to remotely build a concrete support cylinder in an abandoned mine required the coordination of mechanical system and concrete design. The mechanical system was designed to remote place concrete in a cylindrical shape. The concrete was designed to meet the requirements of low slump with high enough strength to resist the forces applied by the ground above mine. The support cylinder is fabricated through an 8-inch borehole by pumping concrete through a second 4-in pipe inside the borehole. The 4-in pipe has a flexible trunk on the lower end that is bent from the surface when it is inside the mine void. When pumping starts, the 4-in pipe is rotated and a spiral of concrete is placed on the mine floor. Operation continues until the concrete seals at the roof. A normal weight concrete as recommended by ACI 211 having a maximum slump of 1--2 in, a maximum coarse aggregate size of 1/2 in, and a minimum compressive strength of 5,000 psi was used. Cylinders have been fabricated to roof heights of 6 ft. There does not appear to be a technical height limitation. The concrete cylinder can support up to 40 x 10 6 lbs when fully cured and filled with gravel, depending on cylinder diameter

Aspects of clay/concrete interactions

International Nuclear Information System (INIS)

Oscarson, D.W.; Dixon, D.A.; Onofrei, M.

1997-01-01

In the Canadian concept for nuclear fuel waste management, both clay-based materials and concrete are proposed for use as barriers, seals or supporting structures. The main concern when clays and concrete are in proximity is the generation of a high-pH environment by concrete since clay minerals are relatively unstable at high pH. Here we examine the OH - -generating capacity of two high-performance concretes when in contact with several solutions. We also investigate various aspects of claylconcrete interactions. They are: (1) the alkalimetric titration of clay suspensions, (2) the effect of Ca(OH) 2 (portlandite) on the swelling and hydraulic properties of compacted bentonite, and (3) the influence of cement grout on a backfill clay retrieved from the 900-d Buffer/Container Experiment at the Underground Research Laboratory of AECL. The results indicate that although high-performance concretes establish significantly lower poresolution pH (9 to 10) than does ordinary portland cement, the pH is still somewhat higher than that of clay/groundwater systems of about pH 8. Hence, even if high-performance concrete is used in a disposal vault, the potential still exists for clay minerals to alter over long periods of time if in contact with this concrete. The data show, however, that clays have a substantial buffering capacity, and clay-based barriers can thus neutralize much of the OH - potentially released from concrete in a vault. Moreover, even after reacting for 120 d at 85 o C with up to 5 wt.% Ca(OH) 2 , compacted bentonite (dry density = 1.2 Mg/m 3 ) retains much of its swelling capacity and has a permeability low enough (hydraulic conductivity ≤ 10 -11 m/s) to ensure that molecular diffusion will be the main transport mechanism through compacted clay-based barriers. Furthermore, according to X-ray diffractometry, the clay mineral component of backfill was not altered by contact with a cement grout for 900 d in the Buffer/Container Experiment

Radiation shielding and effective atomic number studies in different types of shielding concretes, lead base and non-lead base glass systems for total electron interaction: A comparative study

International Nuclear Information System (INIS)

Kurudirek, Murat

2014-01-01

Highlights: • Radiation shielding calculations for concretes and glass systems. • Assigning effective atomic number for the given materials for total electron interaction. • Glass systems generally have better shielding ability than concretes. - Abstract: Concrete has been widely used as a radiation shielding material due to its extremely low cost. On the other hand, glass systems, which make everything inside visible to observers, are considered as promising shielding materials as well. In the present work, the effective atomic numbers, Z eff of some concretes and glass systems (industrial waste containing glass, Pb base glass and non-Pb base glass) have been calculated for total electron interaction in the energy region of 10 keV–1 GeV. Also, the continuous slowing down approximation (CSDA) ranges for the given materials have been calculated in the wide energy region to show the shielding effectiveness of the given materials. The glass systems are not only compared to different types of concretes but also compared to the lead base glass systems in terms of shielding. Moreover, the obtained results for total electron interaction have been compared to the results for total photon interaction wherever possible. In general, it has been observed that the glass systems have superior properties than most of the concretes over the high-energy region with respect to the electron interaction. Also, glass systems without lead show better electron stopping than lead base glasses at some energy regions as well. Along with the photon attenuation capability, it is seen that Fly Ash base glass systems have not only greater electron stopping capability but also have greater photon attenuation especially in high energy region when compared with standard shielding concretes

Radiation shielding and effective atomic number studies in different types of shielding concretes, lead base and non-lead base glass systems for total electron interaction: A comparative study

Energy Technology Data Exchange (ETDEWEB)

Kurudirek, Murat, E-mail: mkurudirek@gmail.com

2014-12-15

Highlights: • Radiation shielding calculations for concretes and glass systems. • Assigning effective atomic number for the given materials for total electron interaction. • Glass systems generally have better shielding ability than concretes. - Abstract: Concrete has been widely used as a radiation shielding material due to its extremely low cost. On the other hand, glass systems, which make everything inside visible to observers, are considered as promising shielding materials as well. In the present work, the effective atomic numbers, Z{sub eff} of some concretes and glass systems (industrial waste containing glass, Pb base glass and non-Pb base glass) have been calculated for total electron interaction in the energy region of 10 keV–1 GeV. Also, the continuous slowing down approximation (CSDA) ranges for the given materials have been calculated in the wide energy region to show the shielding effectiveness of the given materials. The glass systems are not only compared to different types of concretes but also compared to the lead base glass systems in terms of shielding. Moreover, the obtained results for total electron interaction have been compared to the results for total photon interaction wherever possible. In general, it has been observed that the glass systems have superior properties than most of the concretes over the high-energy region with respect to the electron interaction. Also, glass systems without lead show better electron stopping than lead base glasses at some energy regions as well. Along with the photon attenuation capability, it is seen that Fly Ash base glass systems have not only greater electron stopping capability but also have greater photon attenuation especially in high energy region when compared with standard shielding concretes.

Reinforced sulphur concrete

NARCIS (Netherlands)

2014-01-01

Reinforced sulphur concrete wherein one or more metal reinforcing members are in contact with sulphur concrete is disclosed. The reinforced sulphur concrete comprises an adhesion promoter that enhances the interaction between the sulphur and the one or more metal reinforcing members.

Numerical modeling of hybrid fiber-reinforced concrete (hyfrc)

International Nuclear Information System (INIS)

Hameed, R.; Turatsinze, A.

2015-01-01

A model for numerical simulation of mechanical response of concrete reinforced with slipping and non slipping metallic fibers in hybrid form is presented in this paper. Constitutive law used to model plain concrete behaviour is based on plasticity and damage theories, and is capable to determine localized crack opening in three dimensional (3-D) systems. Behaviour law used for slipping metallic fibers is formulated based on effective stress carried by these fibers after when concrete matrix is cracked. A continuous approach is proposed to model the effect of addition of non-slipping metallic fibers in plain concrete. This approach considers the constitutive law of concrete matrix with increased fracture energy in tension obtained experimentally in direct tension tests on Fiber Reinforced Concrete (FRC). To simulate the mechanical behaviour of hybrid fiber-reinforced concrete (HyFRC), proposed approaches to model non-slipping metallic fibers and constitutive law of plain concrete and slipping fibers are used simultaneously without any additive equation. All the parameters used by the proposed model have physical meanings and are determined through experiments or drawn from literature. The model was implemented in Finite Element (FE) Code CASTEM and tested on FRC prismatic notched specimens in flexure. Model prediction showed good agreement with experimental results. (author)

Connecting to concrete: wireless monitoring of chloride ions in concrete structures

NARCIS (Netherlands)

Abbas, Yawar; ten Have, Bas; Hoekstra, Gerrit I.; Douma, Arjan; de Bruijn, Douwe; Olthuis, Wouter; van den Berg, Albert

2015-01-01

For the first time, chloride ions are measured wirelessly in concrete. The half-cell potential of a silver/silver chloride (Ag/AgCl) electrode, which corresponds to the concentration of chloride ions, is measured wirelessly. The sensor system (the Ag/AgCl and a reference electrode) is embedded in

Development of guidelines for transportation of prestressed concrete girders.

Science.gov (United States)

2011-11-01

"Prestressed concrete girders are an economical superstructure system for bridges. With the : advent of higher strength concretes and more effi cient cross sections, the use of long span (>100 : ft.) prestressed girders are now specifi ed. Such long ...

The use of a concrete additive to eliminate returned concrete waste volumes

Directory of Open Access Journals (Sweden)

Bester Johannes

2017-01-01

Full Text Available This paper investigates the effects of the use of a recently developed two-component powdered product made from polymers and inorganic compounds that can be mechanically mixed into returned fresh ready-mix concrete to allow for the separation of the concrete into fine and coarse aggregates. This allows for the re-use of the returned concrete as aggregates in the manufacturing of new concrete. The returned concrete waste can therefore be eliminated, thus reducing virgin aggregate usage, as well as reducing the environmental impact of returned concrete. In this study, the treated recycled fresh concrete was separated into fine and coarse aggregates, and then used at replacement levels of 0%, 25%, 50%, 75% and 100%. The effect of the product on the material classification, and on important fresh and hardened properties of the concrete for the above-mentioned replacement values was tested. For the fine aggregate, the results indicate minimal changes in both the fresh and hardened properties. For the coarse aggregate, the results show a marked improvement of flexural strength with an increase in replacement value when coarse aggregates are used. Very high replacement levels may be used with very little effect on the quality of the new concrete.

Concrete Fibrations

OpenAIRE

Pagnan, Ruggero

2017-01-01

As far as we know, no notion of concrete fibration is available. We provide one such notion in adherence to the foundational attitude that characterizes the adoption of the fibrational perspective in approaching fundamental subjects in category theory and discuss it in connection with the notion of concrete category and the notions of locally small and small fibrations. We also discuss the appropriateness of our notion of concrete fibration for fibrations of small maps, which is relevant to a...

Utilization of waste glass in translucent and photocatalytic concrete

NARCIS (Netherlands)

Spiesz, P.; Rouvas, S.; Brouwers, H.J.H.

2016-01-01

Abstract This article addresses the development of a translucent and air purifying concrete containing waste glass. The concrete composition was optimized applying the modified Andreasen & Andersen model to obtain a densely packed system of granular ingredients. Both untreated (unwashed) and washed

Flexural Behaviour of Precast Aerated Concrete Panel (PACP with Added Fibrous Material: An Overview

Directory of Open Access Journals (Sweden)

Abdul Rahim Noor Hazlin

2017-01-01

Full Text Available The usage of precast aerated concrete panel as an IBS system has become the main alternative to conventional construction system. The usage of this panel system contributes to a sustainable and environmental friendly construction. This paper presents an overview of the precast aerated concrete panel with added fibrous material (PACP. PACP is fabricated from aerated foamed concrete with added Polypropylene fibers (PP. The influence of PP on the mechanical properties of PACP are studied and reviewed from previous research. The structural behaviour of precast concrete panel subjected to flexure load is also reviewed. It is found that PP has significant affects on the concrete mixture’s compressive stregth, tensile strength and flexural strength. It is also found that PP manage to control the crack propagation in the concrete panel.

Maintenance and preservation of concrete structures. Report 3: Abrasion-erosion resistance of concrete

Science.gov (United States)

Liu, T. C.

1980-07-01

This report describes a laboratory test program on abrasion-erosion resistance of concrete, including the development of a new underwater abrasion-erosion test method. This program was designed to evaluate the relative abrasion-erosion resistance of various materials considered for use in the repair of erosion-damaged concrete structures. The test program encompassed three concrete types (conventional concrete, fiber-reinforced concrete, and polymer concrete); seven aggregate types (limestone, chert, trap rock, quartzite, granite, siliceous gravel, and slag); three principal water-cement rations (0.72, 0.54, and 0.40); and six types of surface treatment (vacuum, polyurethane coating, acrylic mortar coating, epoxy mortar coating, furan resin mortar coating, and iron aggregate topping). A total of 114 specimens made from 41 batches of concrete was tested. Based on the test data obtained, a comprehensive evaluation of the effects of various parameters on the abrasion-erosion resistance of concrete was presented. Materials suitable for use in the repair of erosion-damaged concrete structures were recommended. Additional work to correlate the reported findings with field performance was formulated.

Effect of High Temperature or fire on heavy weight concrete properties used in nuclear facilities

International Nuclear Information System (INIS)

Sakr, K.

2003-01-01

In the present work the effect of different duration (1, 2 and 3 hours) of high temperatures (250 degree C, 500 degree C, 750 degree C and 950 degree C) on the physical and mechanical properties of heavy concrete shields were studied. The effect of fire fitting systems on ordinary concrete was investigated. The work was extended to determine the effect of high temperature or accidental fire on the radiation properties of heavy weight concrete. Results showed that ilmenite concrete had the highest density, absorption, and modulus of elasticity when compared to the other types of studied concrete and it had also higher values of compressive, tensile, bending and bonding strength than ordinary or baryte concrete. Ilmenite concrete had the highest attenuation of transmitted gamma rays in comparing to gravel concrete and baryte concrete. Ilmenite concrete was more resistant to elevated temperature than gravel concrete and baryte concrete. Foam or air as a fire fitting system in concrete structure that exposed to high temperature or accidental fire proved that better than water

Demonstration experience with an abrasive blasting technique for decontaminating concrete pads

International Nuclear Information System (INIS)

Devgun, J.S.; Land, R.R.; Doane, R.W.

1990-01-01

A demonstration was performed for decontaminating a radioactivity contaminated concrete pad with a portable abrasive blasting system. The system utilizes a rotating blast wheel that scours the concrete surface with metal abrasive. The metal abrasive, pulverized concrete dust, and contaminants rebound into a separator chamber. The reusable metal abrasive is recycled, and the pulverized media are removed to an integral dust collection system. The exhaust is HEPA filtered to minimize release of airborne contaminants. However, the technique had limited success in reducing contamination around the cracks and seams in the concrete where the higher activity levels of contamination were detected during the radiological survey before the cleanup. The technique can be successful and cost-effective in decontaminating large areas of low contamination; however, careful characterization and planning are necessary. 3 refs., 3 figs., 1 tabs

Lightweight concrete materials and structural systems for water tanks for thermal storage. Final report

Energy Technology Data Exchange (ETDEWEB)

Buckman, R.W. Jr.; Elia, G.G.; Ichikawa, Y.

1980-12-01

Thermally efficient hot water storage tanks were designed, fabricated and evaluated. The tanks were made using cellular concrete at a nominal density of 100 lb/ft/sup 3/ for the structural elements and at a 30 lb/ft/sup 3/ density for the insulating elements. Thermal performance testing of the tanks was done using a static decay test since the test procedure specified in ASHRAE 94-77 was not experimentally practical. A series of composition modifications to the cellular concrete mix were investigated and the addition of alkaline resistant glass fibers was found to enhance the mechanical properties at no sacrifice in thermal behavior. Economic analysis indicated that cellular concrete provides a cost-effective insulating material. The total portability of the plant for producing cellular concrete makes cellular concrete amenable to on-site fabrication and uniquely adaptable to retrofit applications.

Modeling and assessment of concrete and the energy infrastructure

International Nuclear Information System (INIS)

Guthrie, G.; Carey, J.

1998-01-01

This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Concrete is an essential component of the energy infrastructure. The characteristics of concrete that determine its effectiveness in any application--be it construction (e.g., roads, bridges, dams) or waste isolation--result from the chemical and structural evolution of the particular concrete structure. Geochemical and mineralogical factors are among the most important, yet most overlooked, controls of this evolutionary process. This project is geared at using a combination of advanced geochemical and mineralogical experimentation, characterization, and modeling (much of which was developed to understand geological systems such as Yucca Mountain) to understand the evolution of concrete in a mechanistic way. The goal was to develop a systematic approach to problems ranging from premature degradation of concrete to the design of next-generation concretes

The behaviour of concrete under attack of liquid steel

International Nuclear Information System (INIS)

Schneider, U.; Ehm, C.; Diederichs, U.

1983-01-01

Investigations were carried out to study the interaction between concrete and liquid steel. Different types and different forms of concrete were investigated at temperatures of liquid steel between 1.600 and 2.600 0 C. The liquid steel of 1.600 0 C was produced in an induction furnace, the liquid steel of 2.600 0 C was produced in concrete crucibles by metallothermic reactions. The reactions occuring during the interaction of concrete and liquid steel may be summarized as follows: - Concrete reacts violently upon sudden loading with high temperatures and high heat fluxes. Great quantities of steam and gases are generated. The mechanical strength decreases rapidly with increasing temperature. -At about 1.200 0 C concrete begins to melt. First the cement matrix melts, than the aggregates melt. The melts of different concretes consist of different constituents and their reactions with liquid steel vary. The temperature of the liquid steel significantly influences the intensity of the reactions and the erosion rates. - The erosion rates amounted to 30 mm/min, when liquid steel was produced in concrete crucibles. When cylindrical concrete specimens were immersed in molten steel the rate of melting off amounted up to 66 mm/min. - The dissipation of heat during the interaction brings about that the reactions between concrete and liquid steel vanish gradually, if no additional energy is fed into the system. (orig.)

Doses of the staff during the spent fuel assemblies transportation and storage in Nuhmos 56V concrete system

International Nuclear Information System (INIS)

Atoyan, V.; Muradyan, A.

2003-01-01

The NUHMOS 56V concrete system provides long-term interim storage (50 years) for spent fuel assemblies, which have been out of the reactor for a sufficient period of time. It consists from horizontal storage modules. The fuel assemblies are confined in a helium atmosphere by a canister containment pressure vessel. The canister is protected and shielded by a massive reinforced concrete module. Decay heat is removed from the canister and concrete module by a passive natural draft convection ventilation system. The project of storage does not foresee the radiation monitoring inside of building and around it. But we provided and realize the radiation monitoring program around storage, it includes tree phases: - determination the zero background around the building before storage put in exploiting; - monitoring of the radioactive particles in air (additional aspiration plant); dose rate monitoring by portable dosimeters and soil monitoring during the process of the fuel storage; - constantly after the completion the fuel storage process - monitoring of the radioactive particles in air (additional aspiration plant); dose rate monitoring by portable dosimeters, and soil monitoring. Also designed the dose rate monitoring by the dosimeter RME 3 with the transfer of data by radio channel to central monitor. The canistered spent fuel assemblies are transferred from the plant's spent fuel pool to the concrete storage modules in a transfer cask. The cask is aligned with the storage module and the canister and inserted into the module by means of a hydraulic ram. The system is a totally passive installation that is designed to provide shielding and safe confinement of spent fuel for a range of postulated accident conditions and natural phenomena. (authors)

LIGHTWEIGHT CONCRETE BASED GRANSHLAK

Directory of Open Access Journals (Sweden)

NETESA M. I.

2016-02-01

Full Text Available Raising of problem. Concrete advisable to obtain a low strength with local secondary resources for recycling and reduce the environmental burden on the environment. But it is important to design such concrete compositions with a reduced flow of cement. It is known that the coefficient of efficiency of use of cement in the concrete of the heavy and B10 is less than about 0.5, which is almost two times smaller than in class B15 concrete and above. Even lower coefficient of efficiency in light concrete cement low strength. Therefore, it is important to find patterns determining the composition of lightweight concrete based on local-products industry with more efficient use of cement in them. Purpose.. Based on the analysis of earlier research results, including with the use of methods of mathematical planning of experiments to determine the concrete contents, which can provide the requirements for the underlying layers of the floor, the compressive strength of which should correspond to the class B5. It is important to provide the required strength at minimum flow of the cement, which is the most expensive and energy-intensive part of concrete. Conclusion. Analysis of the test results of control samples of concrete in 28-day-old, the following laws. The required tensile strength of concrete compressive strength of 7.0 MPa can be obtained in the test range when used in formulations as a filler as the Dnieper hydroelectric power station fly ash and tailings Krivoy Rog iron ore YuGOK. To ensure providing the required characteristic strength of the concrete in the underlying layers of the floor is advisable to use a nominal composition per cubic meter of concrete: cement 160 kg granshlaka Plant named after Petrovsky, 675 kg of fly ash Dnieper HPP 390 kg, 400 kg of sand, 230 liters of water. Thus, while ensuring rational grain composition components can obtain the desired strength lightweight concrete based granshlaka plant Petrovsky, using as fillers

How PE tape performs under concrete coating

International Nuclear Information System (INIS)

Dritt, H.J.

1984-01-01

The program objectives were to evaluate the performance of polyethylene tape plant coating and fusion bonded epoxy powder systems with particular respect to the following: 1. Concrete coating application procedures; 2. The shear resistance during laying and retrieving operations of the coating at the various interfaces (a) Pipe and anti-corrosion coating; (b) Anti-corrosion coating and outerwrap; (c) Overlap areas of the anti-corrosion and outerwrap layers; (d) Between concrete and the various corrosion coatings during laying and retrieving operations. 3. Resistance to damage of the coating as a consequence of cracking or slippage of the concrete weight coating. 4. Ability of various coatings to withstand the damage during concrete application by both impact and compression methods; 5. Evaluation of tape and shrink sleeve joint coatings at the cut-back area as well as performance of tape under hot asphalt coating

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..

Aesthetic coatings for concrete bridge components

Science.gov (United States)

Kriha, Brent R.

This thesis evaluated the durability and aesthetic performance of coating systems for utilization in concrete bridge applications. The principle objectives of this thesis were: 1) Identify aesthetic coating systems appropriate for concrete bridge applications; 2) Evaluate the performance of the selected systems through a laboratory testing regimen; 3) Develop guidelines for coating selection, surface preparation, and application. A series of site visits to various bridges throughout the State of Wisconsin provided insight into the performance of common coating systems and allowed problematic structural details to be identified. To aid in the selection of appropriate coating systems, questionnaires were distributed to coating manufacturers, bridge contractors, and various DOT offices to identify high performing coating systems and best practices for surface preparation and application. These efforts supplemented a literature review investigating recent publications related to formulation, selection, surface preparation, application, and performance evaluation of coating materials.

Concrete and prestressing process, container made with this concrete

International Nuclear Information System (INIS)

Gerard, M.

1992-01-01

Shape memory alloy fibers or heat shrinking fibers are encapsulated in a standard concrete. Prestressed concrete is obtained by heat treatment. Application is made to the fabrication of radioactive waste containers

Neural correlates of concreteness in semantic categorization.

Science.gov (United States)

Pexman, Penny M; Hargreaves, Ian S; Edwards, Jodi D; Henry, Luke C; Goodyear, Bradley G

2007-08-01

In some contexts, concrete words (CARROT) are recognized and remembered more readily than abstract words (TRUTH). This concreteness effect has historically been explained by two theories of semantic representation: dual-coding [Paivio, A. Dual coding theory: Retrospect and current status. Canadian Journal of Psychology, 45, 255-287, 1991] and context-availability [Schwanenflugel, P. J. Why are abstract concepts hard to understand? In P. J. Schwanenflugel (Ed.), The psychology of word meanings (pp. 223-250). Hillsdale, NJ: Erlbaum, 1991]. Past efforts to adjudicate between these theories using functional magnetic resonance imaging have produced mixed results. Using event-related functional magnetic resonance imaging, we reexamined this issue with a semantic categorization task that allowed for uniform semantic judgments of concrete and abstract words. The participants were 20 healthy adults. Functional analyses contrasted activation associated with concrete and abstract meanings of ambiguous and unambiguous words. Results showed that for both ambiguous and unambiguous words, abstract meanings were associated with more widespread cortical activation than concrete meanings in numerous regions associated with semantic processing, including temporal, parietal, and frontal cortices. These results are inconsistent with both dual-coding and context-availability theories, as these theories propose that the representations of abstract concepts are relatively impoverished. Our results suggest, instead, that semantic retrieval of abstract concepts involves a network of association areas. We argue that this finding is compatible with a theory of semantic representation such as Barsalou's [Barsalou, L. W. Perceptual symbol systems. Behavioral & Brain Sciences, 22, 577-660, 1999] perceptual symbol systems, whereby concrete and abstract concepts are represented by similar mechanisms but with differences in focal content.

Let’s Get Concrete!

DEFF Research Database (Denmark)

Jones, Candace; Boxenbaum, Eva

whereas in the United States market and professional logics interacted: manufacturers cooperated to create standards for concrete and appealed to architects as consumers. Our findings also illuminate that concrete was legitimated initially by imitation of stone, but this strategy soon de......-legitimated not only concrete but also stone. Concrete was perceived as merely imitative and thus inauthentic. For concrete to become a legitimate and widely adopted material, architects had to theorize concrete as unique material with distinctive aesthetic possibilities, which led to new kinds of buildings and new...... architectural styles. Our study illuminates the key role that materials and aesthetics played within architects’ professional logic and shaped processes of institutional change....

Strain rate effects for spallation of concrete

Science.gov (United States)

Häussler-Combe, Ulrich; Panteki, Evmorfia; Kühn, Tino

2015-09-01

Appropriate triaxial constitutive laws are the key for a realistic simulation of high speed dynamics of concrete. The strain rate effect is still an open issue within this context. In particular the question whether it is a material property - which can be covered by rate dependent stress strain relations - or mainly an effect of inertia is still under discussion. Experimental and theoretical investigations of spallation of concrete specimen in a Hopkinson Bar setup may bring some evidence into this question. For this purpose the paper describes the VERD model, a newly developed constitutive law for concrete based on a damage approach with included strain rate effects [1]. In contrast to other approaches the dynamic strength increase is not directly coupled to strain rate values but related to physical mechanisms like the retarded movement of water in capillary systems and delayed microcracking. The constitutive law is fully triaxial and implemented into explicit finite element codes for the investigation of a wide range of concrete structures exposed to impact and explosions. The current setup models spallation experiments with concrete specimen [2]. The results of such experiments are mainly related to the dynamic tensile strength and the crack energy of concrete which may be derived from, e.g., the velocity of spalled concrete fragments. The experimental results are compared to the VERD model and two further constitutive laws implemented in LS-Dyna. The results indicate that both viscosity and retarded damage are required for a realistic description of the material behaviour of concrete exposed to high strain effects [3].

Strain rate effects for spallation of concrete

Directory of Open Access Journals (Sweden)

Häussler-Combe Ulrich

2015-01-01

Full Text Available Appropriate triaxial constitutive laws are the key for a realistic simulation of high speed dynamics of concrete. The strain rate effect is still an open issue within this context. In particular the question whether it is a material property – which can be covered by rate dependent stress strain relations – or mainly an effect of inertia is still under discussion. Experimental and theoretical investigations of spallation of concrete specimen in a Hopkinson Bar setup may bring some evidence into this question. For this purpose the paper describes the VERD model, a newly developed constitutive law for concrete based on a damage approach with included strain rate effects [1]. In contrast to other approaches the dynamic strength increase is not directly coupled to strain rate values but related to physical mechanisms like the retarded movement of water in capillary systems and delayed microcracking. The constitutive law is fully triaxial and implemented into explicit finite element codes for the investigation of a wide range of concrete structures exposed to impact and explosions. The current setup models spallation experiments with concrete specimen [2]. The results of such experiments are mainly related to the dynamic tensile strength and the crack energy of concrete which may be derived from, e.g., the velocity of spalled concrete fragments. The experimental results are compared to the VERD model and two further constitutive laws implemented in LS-Dyna. The results indicate that both viscosity and retarded damage are required for a realistic description of the material behaviour of concrete exposed to high strain effects [3].

Ultrafine particles in concrete: Influence of ultrafine particles on concrete properties and application to concrete mix design

Energy Technology Data Exchange (ETDEWEB)

Vogt, Carsten

2010-07-01

In this work, the influence of ultrafine particles on concrete properties was investigated. In the context of this work, ultrafine particles (reactive and inert materials) are particles finer than cement. Due to the development of effective superplasticizers, the incorporation of ultrafine particles in concrete is nowadays possible. Different minerals, usually considered inert, were tested. These minerals were also used in combination with reactive silica fume. The modified Andreassen model was used to optimise the particle size distribution and thus the packing density of the complete mix composition. Heat of hydration, compressive strength, shrinkage, frost resistance and the microstructure were investigated.The influence of different ultrafine inert materials on the cement hydration was investigated. The results show that most of the minerals have an accelerating effect. They provide nucleation sites for hydration products and contribute in that way to a faster dissolution of cement grains. Minerals containing calcium were found to influence the early stage of hydration as well. These minerals shortened the dormant period of the cement hydration, the effect is known from limestone filler in self-compacting concrete. In a first test series on concrete, different ultrafine inert particles were used to replace cement. That was done in several ways; with constant water content or constant w/c. The results from this test series show that the best effect is achieved when cement is replaced by suitable ultrafines while the w/c is kept constant. In doing so, the compressive strength can be increased and shrinkage can be reduced. The microstructure is improved and becomes denser with improved packing at microlevel. Efficiency factors (k values) for the ultrafine inert materials were calculated from the compressive strength results. The k values are strongly dependent on the mode of cement replacement, fineness and type of the replacement material and curing time. Drying

Clearance of concrete debris generated from modification work of JRR-3

International Nuclear Information System (INIS)

Satoyama, Tomonori; Nanri, Tomohiro; Kishimoto, Katsumi

2014-01-01

The Japan Atomic Energy Agency (JAEA) planned to apply the clearance system to slightly contaminated concrete debris with radionuclides, which was generated from the modification of the Japan Research Reactor No. 3 (JRR-3) in the Nuclear Science Research Institute (NSRI) of JAEA. The modification work was conducted from 1985 to 1990 and the generated concrete debris has been stored as radioactive waste in interim storage facilities in the NSRI. This is the Japanese first approved of clearance system to concrete debris and stored waste. We established procedures for measuring and evaluating the radioactivity concentration of scored concrete debris. In 2008, the authority approved these procedures for clearance. Since 2009, we have been measuring and evaluating the radioactivity concentration of concrete debris, using the approved procedures. By the end of 2012, the authority had confirmed the correctness of our measurement and evaluation results on about 2,600 tons of concrete debris. About 1,800 tons of those cleared concrete were recycled to flat surface subsidence in the NSRI caused by the Great East Japan Earthquake, and also used as base material to construct new buildings and parking lots in the NSRI. (author)

CONCRETE MIX DESIGN FOR STRUCTURES SUBJECTED TO EXPOSURE CLASS XC1 DEPENDING ON CONCRETE COVER

Directory of Open Access Journals (Sweden)

O. Yu. Cherniakevich

2016-01-01

Full Text Available The reinforced steel corrosion which is the most important problem of reinforced concrete structures durability is generally stipulated for carbonization of concrete surrounding it. Concrete cover calculation at the design stage is predicated one because of the differences in manufacturing conditions and use of constructions. The applying of the probabilistic approaches to the carbonation process modeling allows to get predicated grade of the depth of carbonization of concrete and, thus, to settle minimum concrete cover thickness for a given projected service life of a construction. The procedures for concrete mix design for different strength classes of concrete are described in the article. Current recommendations on assignment of concrete strength class as well as concrete cover are presented. The European Standard EN 206:2013 defines the content requirements for the concrete structures operated in the exposure class XC1, including the minimum values of water-cement ratio, minimum cement content, and minimum strength class of concrete. Since the standard does not include any basis or explanations of the requirements, we made an effort to develop a scientific justification for the mentioned requirements. We developed the probabilistic models for the process of carbonation of concrete based on the concrete mix which was designed using the software VTK-Korroziya. The reinforced concrete structures with concrete cover 20–35 mm operated in the most unfavorable conditions within the exposure class XC1 were analyzed. The corresponding probabilistic calculations of the depth of carbonated concrete are described in the article. 

Concrete portable handbook

CERN Document Server

Woodson, R Dodge

2011-01-01

Whether or not, you are on the job site or back in the office, this book will help you to avoid mistakes, code violations, and wasted time and money. The book's four part treatment begins with constituent materials followed by self contained parts on Concrete Properties, Processes, and Concrete Repair and Rehabilitation. Designed to be an ""all in one"" reference, the author includes a wealth information for the most popular types of testing. This includes: Analysis of Fresh Concrete; Testing Machines; Accelerated Testing Methods; Analysis of Hardened Concrete and Mortar; Core Sampl

Autogenous Deformation of Concrete

DEFF Research Database (Denmark)

Autogenous deformation of concrete can be defined as the free deformation of sealed concrete at a constant temperature. A number of observed problems with early age cracking of high-performance concretes can be attributed to this phenomenon. During the last 10 years , this has led to an increased...... focus on autogenous deformation both within concrete practice and concrete research. Since 1996 the interest has been significant enough to hold international, yearly conferences entirely devoted to this subject. The papers in this publication were presented at two consecutive half-day sessions...... at the American Concrete Institute’s Fall Convention in Phoenix, Arizona, October 29, 2002. All papers have been reviewed according to ACI rules. This publication, as well as the sessions, was sponsored by ACI committee 236, Material Science of Concrete. The 12 presentations from 8 different countries indicate...

Monitoring of concrete structures by using the 14 MeV tagged neutron beams

International Nuclear Information System (INIS)

Sudac, D.; Nad, K.; Obhodas, J.; Valkovic, V.

2013-01-01

The maintenance and repair of reinforced concrete structures, especially those submerged in the sea-water require effective inspection and monitoring techniques for assessing the state of corrosion in the reinforcement material. An underwater inspection system was developed which is able to monitor the corrosion of the reinforcement. The system is composed of a remotely operating vehicle (ROV) equipped with the sealed tube neutron generator (NG). By rotating the NG and by using the associated alpha particle technique it is possible to measure the concrete cover thickness together with the reinforcing bar diameter. The possibility of estimating the carbon and chloride contents in the concrete was investigated. Iron plates of different thickness, covered by 6 cm thick concrete block, were successfully detected and the thickness of the concrete cover was estimated. In addition, reinforcing bar of one and 3 cm in diameter were identified and measured. All measurements could be performed without cleaning the concrete surface from fouling material. -- Highlights: • An underwater inspection system was developed which is able to monitor the state of reinforcement corrosion. • The system is composed of a remotely operating vehicle (ROV) equipped with the sealed tube neutron generator (NG). • All measurements could be performed without cleaning the concrete surface from fouling material

Research reactor decommissioning experience - concrete removal and disposal -

International Nuclear Information System (INIS)

Manning, Mark R.; Gardner, Frederick W.

1990-01-01

Removal and disposal of neutron activated concrete from biological shields is the most significant operational task associated with research reactor decommissioning. During the period of 1985 thru 1989 Chem-Nuclear Systems, Inc. was the prime contractor for complete dismantlement and decommissioning of the Northrop TRIGA Mark F, the Virginia Tech Argonaut, and the Michigan State University TRIGA Mark I Reactor Facilities. This paper discusses operational requirements, methods employed, and results of the concrete removal, packaging, transport and disposal operations for these (3) research reactor decommissioning projects. Methods employed for each are compared. Disposal of concrete above and below regulatory release limits for unrestricted use are discussed. This study concludes that activated reactor biological shield concrete can be safely removed and buried under current regulations

Crack classification in concrete beams using AE parameters

Science.gov (United States)

Bahari, N. A. A. S.; Shahidan, S.; Abdullah, S. R.; Ali, N.; Zuki, S. S. Mohd; Ibrahim, M. H. W.; Rahim, M. A.

2017-11-01

The acoustic emission (AE) technique is an effective tool for the evaluation of crack growth. The aim of this study is to evaluate crack classification in reinforced concrete beams using statistical analysis. AE has been applied for the early monitoring of reinforced concrete structures using AE parameters such as average frequency, rise time, amplitude counts and duration. This experimental study focuses on the utilisation of this method in evaluating reinforced concrete beams. Beam specimens measuring 150 mm × 250 mm × 1200 mm were tested using a three-point load flexural test using Universal Testing Machines (UTM) together with an AE monitoring system. The results indicated that RA value can be used to determine the relationship between tensile crack and shear movement in reinforced concrete beams.

Behaviour of concrete beams reinforced withFRP prestressed concrete prisms

Science.gov (United States)

Svecova, Dagmar

The use of fibre reinforced plastics (FRP) to reinforce concrete is gaining acceptance. However, due to the relatively low modulus of FRP, in comparison to steel, such structures may, if sufficient amount of reinforcement is not used, suffer from large deformations and wide cracks. FRP is generally more suited for prestressing. Since it is not feasible to prestress all concrete structures to eliminate the large deflections of FRP reinforced concrete flexural members, researchers are focusing on other strategies. A simple method for avoiding excessive deflections is to provide sufficiently high amount of FRP reinforcement to limit its stress (strain) to acceptable levels under service loads. This approach will not be able to take advantage of the high strength of FRP and will be generally uneconomical. The current investigation focuses on the feasibility of an alternative strategy. This thesis deals with the flexural and shear behaviour of concrete beams reinforced with FRP prestressed concrete prisms. FRP prestressed concrete prisms (PCP) are new reinforcing bars, made by pretensioning FRP and embedding it in high strength grout/concrete. The purpose of the research is to investigate the feasibility of using such pretensioned rebars, and their effect on the flexural and shear behaviour of reinforced concrete beams over the entire loading range. Due to the prestress in the prisms, deflection of concrete beams reinforced with this product is substantially reduced, and is comparable to similarly steel reinforced beams. The thesis comprises both theoretical and experimental investigations. In the experimental part, nine beams reinforced with FRP prestressed concrete prisms, and two companion beams, one steel and one FRP reinforced were tested. All the beams were designed to carry the same ultimate moment. Excellent flexural and shear behaviour of beams reinforced with higher prestressed prisms is reported. When comparing deflections of three beams designed to have the

Quality control of concrete structures in nuclear power plant, (3)

International Nuclear Information System (INIS)

Takahashi, Hisao; Kawaguchi, Tohru; Oike, Takeshi; Morimoto, Shoichi; Takeshita, Shigetoshi.

1979-01-01

In general, concrete placed in the winter season has a tendency to have lower strength at the age of 4 weeks due to low curing temperature after placement. Therefore, under the Japanese code, the target mix Proportions in the winter season are modified adding an extra correction factor based on air temperature. Meanwhile, the quality control system for mass concrete to be placed in the winter system is indistinct at this stage. It is the aim of this report to present the results of investigations to clarify the following two subjects: (1) whether the correction factor due to temperature is needed or not for mass concrete in the winter season; (2) what kind of curing should be applied to control cylinders for estimating strength of mass concrete. (author)

Quality of concrete plant wastewater for reuse

Directory of Open Access Journals (Sweden)

H. M. Paula

Full Text Available Efficient water use is one of the most important requirements of cleaner production, and the use of the wastewater from concrete production can be an important means to this end. However, there are no Brazilian studies on the quality of concrete plant wastewater and the activities in which such water can be used. This paper aims to evaluate the quality of concrete plant wastewater and to propose guidelines for its treatment for non-potable applications. Wastewater samples were collected from three points in the studied treatment system, and tests were later performed in the laboratory to evaluate the water quality. The results obtained were compared with the limit values for the quality parameters that have been used for the analysis of the non-potable water supply in Brazil. The results indicate a need to at least add coagulation and pH correction processes to the treatment system.

Numerical Study Of The Effects Of Preloading, Axial Loading And Concrete Shrinkage On Reinforced Concrete Elements Strengthened By Concrete Layers And Jackets

International Nuclear Information System (INIS)

Lampropoulos, A. P.; Dritsos, S. E.

2008-01-01

In this study, the technique of seismic strengthening existing reinforced concrete columns and beams using additional concrete layers and jackets is examined. The finite element method and the finite element program ATENA is used in this investigation. When a reinforced jacket or layer is being constructed around a column it is already preloaded due to existing service loads. This effect has been examined for different values of the axial load normalized to the strengthened column. The techniques of strengthening with a concrete jacket or a reinforced concrete layer on the compressive side of the column are examined. Another phenomenon that is examined in this study is the shrinkage of the new concrete of an additional layer used to strengthen an existing member. For this investigation, a simply supported beam with an additional reinforced concrete layer on the tensile side is examined. The results demonstrate that the effect of preloading is important when a reinforced concrete layer is being used with shear connectors between the old and the new reinforcement. It was also found that the shrinkage of the new concrete reduces the strength of the strengthened beam and induces an initial sliding between the old and the new concrete

Offshore concrete structures

International Nuclear Information System (INIS)

Lamas Pardo, M.; Carral Couce, L. M.

2011-01-01

In the offshore industry there are two possible materials for the construction of the hull of a structure; the steel and concrete, with the first one widely used until now, as in the rest of the shiphuidling industry of merchant ships, warships, etc. Materials such as aluminum, GRP or timber areused in small units with lengths lower than 100 m, and in less adverse conditions than in the offshore industry. Nevertheless, some ships/barges have been built of concrete in the past, but have been rather isolated cases which have not changed the practice in the industry. In the First and Second World War were built by the scarcity of materials, while the series of barges by Alfred A. Yee was a rare exception. Other units were also made in concrete, but almost anecdotal. Still, the behaviour of these concrete structures, especially in terms of maintenance, has been excellent. Therefore, the fact that the concrete has not had an adequate reception so far in shipbuilding, does not mean that in will not be the material best suited for the offshore industry in the future. The extra displacement and associated fuel costs in concrete ships have been found prohibitive in the past. But the loss of mobility of a concrete hull in relation to a steel hull can be perfectly offset by the advantages offered by the concrete, as the shipping and offshore industry have very different priorities. One of the main differences in these priorities is in terms of maintenance and resistance to fatigue, precisely where the concrete performs better. ships can easily be dry docked for maintenance and repair, while in the offshore platforms these works have to be done in situ so maintenance and fatigue are crucial to them. Besides these, the concrete has other advantages according to findings of several studies. And although they are interested in the conclusions that the makes as they came from people in the concrete industry, the fact that in recent years concrete offshore unit shave been built

Development of prestressed concrete containment vessels

International Nuclear Information System (INIS)

Yuji, Hideo; Kuniyoshi, Mutsumu; Nagata, Kaoru

1983-01-01

This paper presents a summary of evaluations for the selection of the structural and prestressing system type to be employed for the first domestic Prestressed Concrete Containment Vessel (PCCV) in Japan. This paper also discusses characteristic features in the design of the liner plate system provided on the PCCV inner surface to assure its leak-tight integrity. Prestressed concrete containment vessels so far constructed in foreign countries are to a considerable extent of different structural types, depending on differences in dome shapes, prestressing systems and number of buttresses. These differences are caused not only by differences in design philosophy and construction practices, but also by difference in the level of technology of the times when the individual containment vessels are being constructed. In the investigation reported herein, the most suitable types of PCCV and Prestressing Systems were determined as the results of an overall comparative evaluation of data and information obtained from PCCV's so far constructed from the design, construction and cost aspects, taking into consideration the seismic criteria, available technology, construction practices, regulations and technical standards in Japan. The function of the liner plate system requires the liner to have enough deformability so that the liner deformation can be consistent with the PCCV concrete deformation. Therefore, in the design of the liner plate system a method for evaluating liner deformability was employed, instead of the stress evaluation method which is widely used in the design of ordinary structures. (author)

Self-compacting concrete (SCC)

DEFF Research Database (Denmark)

Geiker, Mette Rica

2008-01-01

In many aspects Self-Compacting Concrete (SCC, “Self-Consolidating Concrete” in North America) can be considered the concrete of the future. SCC is a family of tailored concretes with special engineered properties in the fresh state. SCC flows into the formwork and around even complicated...... reinforcement arrangements under its own weight. Thus, SCC is not vibrated like conventional concrete. This drastically improves the working environment during construction, the productivity, and potentially improves the homogeneity and quality of the concrete. In addition SCC provides larger architectural...

Induced radioactivity in Bevatron concrete radiation shielding blocks

International Nuclear Information System (INIS)

Moeller, G.C.; Donahue, R.J.

1994-07-01

The Bevatron accelerated protons up to 6.2 GeV and heavy ions up to 2.1 GeV/amu. It operated from 1954 to 1993. Radioactivity was induced in some concrete radiation shielding blocks by prompt radiation. Prompt radiation is primarily neutrons and protons that were generated by the Bevatron's primary beam interactions with targets and other materials. The goal was to identify the gamma-ray emitting nuclides (t 1/2 > 0.5 yr) that could be present in the concrete blocks and estimate the depth at which the maximum radioactivity presently occurs. It is shown that the majority of radioactivity was produced via thermal neutron capture by trace elements present in concrete. The depth of maximum thermal neutron flux, in theory, corresponds with the depth of maximum induced activity. To estimate the depth at which maximum activity occurs in the concrete blocks, the LAHET Code System was used to calculate the depth of maximum thermal neutron flux. The primary beam interactions that generate the neutrons are also modeled by the LAHET Code System

Photocatalyticpaving concrete

Directory of Open Access Journals (Sweden)

Lyapidevskaya Ol'ga Borisovna

2014-02-01

Full Text Available Today bituminous concrete is a conventional paving material. Among its advantages one can name dustlessness and noiselessness, fine wear (up to 1 mm a year and fine maintainability. As the main disadvantages of this material one can name high slipperiness under humidification, low durability and weather resistance. Besides that, during placement of the bituminous concrete a lot of different air pollutants are emitted, which are harmful for environment and human’s health (they are listed in the paper according to the US Environmental Protection Agency materials. As an alternative, one can use cement-concrete pavement, which is in many ways more efficient than the bituminous concrete. It is proposed to enhance environmental performance of the cement-concrete pavement via usage of photocatalysis. The mechanism of different photocatalytic reactions is described in the paper, namely heterogeneous and homogeneous photocatalysis, photo-induces, photoactivated catalysis and catalytical photoreactions. It is pro-posed to use heterogeneous photocatalysis with titanium dioxide as a photocatalyst. The mechanism of photo oxidation of air contaminants, with the usage of titanium dioxide is2described. The paper sets problems, connected with the sensibilization of TiOto thevisible light (it is proposed to use titanium dioxide, doped with the atoms of certain elements to increase its sensibility to the visible light and with the development of a new photocatalytic paving concrete, which will meet the requirements, specified for paving in the climatic and traffic conditions of the Russian Federation.

Fibre-concrete container

International Nuclear Information System (INIS)

2000-01-01

In this leaflet the fibre-concrete container for radioactive wastes is described. The fibre container is made of fibre-concrete that contains cement, aggregate, sand, filter, flame-silica, super-plastificator, water and scattered metal fibres. The fibre-concrete container has a dice shape with outer dimension 1.7 x 1.7 x 1.7 m. It is mounted of a container body, a container cover and two caps. Total weight of container is 4,240 kg, maximum weight of loaded container do not must exceed 15,000 kg. The physical and mechanical properties of the fibre-concrete container are described in detail. The fibre-concrete container manufactured for storing of low and intermediate radioactive wastes. A fibre-concrete container utilization to store of radioactive wastes solves these problems: increase of stability of stored packages of radioactive waste; watertightness within 300 years at least; static stability of bearing space; better utilization of bearing spaces; insulation of radioactive waste in a case of seismic and geological event; increase of fire resistance; and transport of radioactive waste

Very heavy iron-punching concretes

International Nuclear Information System (INIS)

Dubois, F.

1966-01-01

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) [fr

Increased Durability of Concrete Made with Fine Recycled Concrete Aggregates Using Superplasticizers.

Science.gov (United States)

Cartuxo, Francisco; de Brito, Jorge; Evangelista, Luis; Jiménez, José Ramón; Ledesma, Enrique F

2016-02-08

This paper evaluates the influence of two superplasticizers (SP) on the durability properties of concrete made with fine recycled concrete aggregate (FRCA). For this purpose, three families of concrete were tested: concrete without SP, concrete made with a regular superplasticizer and concrete made with a high-performance superplasticizer. Five volumetric replacement ratios of natural sand by FRCA were tested: 0%, 10%, 30%, 50% and 100%. Two natural gravels were used as coarse aggregates. All mixes had the same particle size distribution, cement content and amount of superplasticizer. The w/c ratio was calibrated to obtain similar slump. The results showed that the incorporation of FRCA increased the water absorption by immersion, the water absorption by capillary action, the carbonation depth and the chloride migration coefficient, while the use of superplasticizers highly improved these properties. The incorporation of FRCA jeopardized the SP's effectiveness. This research demonstrated that, from a durability point of view, the simultaneous incorporation of FRCA and high-performance SP is a viable sustainable solution for structural concrete production.

Durable concrete for a waste repository - Measurement of ionic ingress

International Nuclear Information System (INIS)

Feldman, R.F.; Beaudoin, J.J.; Philipose, K.E.

1990-01-01

A waste repository for the below ground disposal of low level radioactive waste is planned at Chalk River Nuclear Laboratories. It relies greatly on the durability of concrete for the required 500 year service life. A research program to design durable concrete and predict its service life is in progress. The degradation of the concrete depends to a large extent on the rate of ingress of corrosive agents. Penetration of chloride and sulfate ions are particularly relevant. Twenty mix formulations were developed to create various types and qualities of concrete, and to study their behavior in different site environmental conditions. A total of 1,000 concrete specimens are being exposed at 20C and 45C to 25 different combinations of the corrosive agents including CO 2 . Procedures to measure the ionic profiles and to determine the factors controlling diffusion of the ions in the various concretes have been developed. Results of selected concrete systems exposed to chloride and sulfate solutions for 1 year are presented and discussed in terms of pore structure and permeability parameters of the concrete

Requirements for thermal insulation on prestressed concrete reactor vessels

International Nuclear Information System (INIS)

Neylan, A.J.; Wistrom, J.D.

1979-01-01

During the past decade, extensive design, construction, and operating experience on concrete pressure vessels for gas-cooled reactor applications has accumulated. Excellent experience has been obtained to date on the structural components (concrete, prestressing systems, liners, penetrations, and closures) and the thermal insulation. Three fundamentally different types of insulation systems have been employed to ensure the satisfactory performance of this component, which is critical to the overall success of the prestressed concrete reactor vessel (PCRV). Although general design criteria have been published, the requirements for design, materials, and construction are not rigorously addressed in any national or international code. With the more onerous design conditions being imposed by advanced reactor systems, much greater attention has been directed to advance the state of the art of insulation systems for PCRVs. This paper addresses some of the more recent developments in this field being performed by General Atomic Company and others. (author)

Impact of recycled gravel obtained from low or medium concrete grade on concrete properties

Directory of Open Access Journals (Sweden)

Yasser Abdelghany Fawzy

2018-04-01

Full Text Available This paper investigates the effect of recycled gravel obtained from low (Gl or medium (Gm concrete grade on fresh property of concrete (slump, mechanical properties (compressive-splitting tensile strength and mass transport properties (ISAT-sorptivity of concrete containing dolomite as a natural coarse aggregate. Concrete specimens were prepared with cement, water, sand and dolomite admixed with recycled gravel. The percentage of recycled gravel/dolomite was 0:100, 25:75, 50:50 and 75:25 at w/c = 0.50, 0.55 and 0.60. The effect of silica fume and bonding admixture at w/c = 0.55 on concrete properties were also considered. The results indicated that, increasing the percentage of recycled gravel/dolomite led to decreasing the slump. All mechanical properties of concrete discussed were inversely affected by increasing percentage of recycled gravel/dolomite from low and medium concrete. Adding 10% SF or bonding admixture increased the mechanical properties of concrete. Mass transport properties of concrete (ISAT-sorptivity were enhanced by decreasing the percentage of recycled gravel/dolomite. The optimum percentage of recycled gravel/dolomite = 25%. Keywords: Recycled gravel, Concrete, Silica fume, Compressive strength, Mass transport

Phenomena of Foamed Concrete under Rolling of Aircraft Wheels

Science.gov (United States)

Jiang, Chun-shui; Yao, Hong-yu; Xiao, Xian-bo; Kong, Xiang-jun; Shi, Ya-jie

2014-04-01

Engineered Material Arresting System (EMAS) is an effective technique to reduce hazards associated with aircraft overrunning runway. In order to ascertain phenomena of the foamed concrete used for EMAS under rolling of aircraft wheel, a specially designed experimental setup was built which employed Boeing 737 aircraft wheels bearing actual vertical loads to roll through the foamed concrete. A number of experiments were conducted upon this setup. It is discovered that the wheel rolls the concrete in a pure rolling manner and crushes the concrete downwards, instead of crushing it forward, as long as the concrete is not higher than the wheel axle. The concrete is compressed into powder in-situ by the wheel and then is brought to bottom of the wheel. The powder under the wheel is loose and thus is not able to sustain wheel braking. It is also found that after being rolled by the wheel the concrete exhibits either of two states, i.e. either 'crushed through' whole thickness of the concrete or 'crushed halfway', depending on combination of strength of the concrete, thickness of the concrete, vertical load the wheel carries, tire dimension and tire pressure. A new EMAS design concept is developed that if an EMAS design results in the 'crushed through' state for the main gears while the 'crushed halfway' state for the nose gear, the arresting bed would be optimal to accommodate the large difference in strength between the nose gear and the main gear of an aircraft.

Performance of shcc with bacteria for concrete patch repair

NARCIS (Netherlands)

Sierra Beltran, M.G.; Jonkers, H.M.; Schlangen, E.

2014-01-01

The overall performance of concrete patch repair systems depends on the durability of and compatibility between the concrete substrate and the repair material. This paper investigates the performance of a new type of SHCC material with embedded bacteria as a repair material. The bacteria are a

Composite Strain Hardening Properties of High Performance Hybrid Fibre Reinforced Concrete

Directory of Open Access Journals (Sweden)

Vikram Jothi Jayakumar

2014-01-01

Full Text Available Hybrid fibres addition in concrete proved to be a promising method to improve the composite mechanical properties of the cementitious system. Fibre combinations involving different fibre lengths and moduli were added in high strength slag based concrete to evaluate the strain hardening properties. Influence of hybrid fibres consisting of steel and polypropylene fibres added in slag based cementitious system (50% CRL was explored. Effects of hybrid fibre addition at optimum volume fraction of 2% of steel fibres and 0.5% of PP fibres (long and short steel fibre combinations were observed in improving the postcrack strength properties of concrete. Test results also indicated that the hybrid steel fibre additions in slag based concrete consisting of short steel and polypropylene (PP fibres exhibited a the highest compressive strength of 48.56 MPa. Comparative analysis on the performance of monofibre concrete consisting of steel and PP fibres had shown lower residual strength compared to hybrid fibre combinations. Hybrid fibres consisting of long steel-PP fibres potentially improved the absolute and residual toughness properties of concrete composite up to a maximum of 94.38% compared to monofibre concrete. In addition, the relative performance levels of different hybrid fibres in improving the matrix strain hardening, postcrack toughness, and residual strength capacity of slag based concretes were evaluated systematically.

Imaging of concrete specimens using inverse synthetic aperture radar

International Nuclear Information System (INIS)

Rhim, Hong C.; Buyukozturk, Oral

2000-01-01

Radar Measurement results of laboratory size concrete specimens are presented in this paper. The purpose of this research work is to study various aspects of the radar method in an effort to develop an improved radar system for nondestructive testing of concrete structures. The radar system used for the study is an Inverse Synthetic Aperture Radar (ISAR), which is capable of transmitting microwaves at three different frequency ranges of 2-3.4, 3.4-5.8, and 8-12 GHz. Radar measurement setup is such that the radar is locates 14.4 m away from a concrete target to satisfy a far-field criterion. The concrete target is rotated for 20 degrees during the measurements for the generation of two-dimensional (cross-range) imagery. Concrete targets used for the measurements have the dimensions of 305 mm (width)x305 mm (height)x92 mm (thickness) with different inside configurations. Comparisons are made for dry and wet specimens, specimens with and without inclusions. Each specimen is made to model various situations that a concrete structure can have in reality. Results show that center frequency, frequency bandwidth, and polarization of the incident wave have different effects on identifying the thickness or inclusions inside concrete specimens. Results also suggest that a certain combination of measurement parameters is suitable for a specific application area. Thus, measurement parameters can be optimized for a specific problem. The findings are presented and discussed in details in the paper. Signal processing schemes implemented for imaging of the specimens are also discussed

Variability in properties of Salado Mass Concrete

International Nuclear Information System (INIS)

Wakeley, L.D.; Harrington, P.T.; Hansen, F.D.

1995-08-01

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 ft 3 to 5.0 yd 3 , 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

Applicability of Clearance Automatic Laser Inspection System to Clearance Measurement of Concrete Segments

International Nuclear Information System (INIS)

Sasaki, M.; Ogino, H.; Hattori, T.

2009-01-01

In the decommissioning of a nuclear power plant, large amounts of metal scrap and concrete segments require disposal when dismantling the nuclear reactor and surrounding facilities. When their activity level is negligible or sufficiently small, they can be regarded as general industrial waste. To distinguish between radioactive and nonradioactive materials, the clearance level for each radionuclide has been determined in units of activity concentration. These clearance levels are indicated in the International Atomic Energy Agency (IAEA) Safety Standards Series No. RS-G-1.7. The Japanese regulatory authority decided in 2005 to adopt the values given in RS-G-1.7 as clearance levels in legislation. Recently, a Clearance Automatic Laser Inspection System (CLALIS) has been developed utilizing gamma-ray measurement, automatic laser shape measurement and Monte Carlo calculation. CLALIS comprises four laser scanners and eight large plastic scintillation detectors surrounded by a 5-cm-thick lead shield. Using three-dimensional (3D) laser scanning, a measurement target, which is placed on the measuring tray, is represented as a dot image. The dot image is converted into voxels after noise removal, and is written in MCNP (A General Monte Carlo N-Particle Transport Code System) input files. When the gamma-ray measurement is carried out, the MCNP calculations are also carried out to obtain the calibration factor and background (BG) correction factors. For the clearance measurement of concrete segments, the effect of gamma-rays from natural radionuclides in the measurement target, such as K-40 and the radioactive decay products of Th-232 and U-238, should be taken into account to ensure adequate waste management. Since NE102A plastic scintillation detectors are used for gamma-ray measurement in CLALIS, it is impossible to distinguish between the count rates of natural radionuclides and contaminants on the basis of gamma-ray energy information. To overcome this problem, the

Working life of cathodic protection systems for concrete structures - Analysis of field data

NARCIS (Netherlands)

Polder, R.B.; Leegwater, G.; Worm, D.; Courage, W.

2012-01-01

Corrosion of reinforcing steel in concrete structures causes concrete cracking, steel diameter reduction and eventually loss of safety. In infrastructure this is mainly due to penetration of chloride ions from de-icing or marine salts. Conventional repair means heavy, labour intensive and costly

Concrete construction engineering handbook

CERN Document Server

Nawy, Edward G

2008-01-01

Provides coverage of concrete construction engineering and technology. This work features discussions focusing on: the advances in engineered concrete materials; reinforced concrete construction; specialized construction techniques; and, design recommendations for high performance.

CRASH TEST AND EVALUATION OF RESTRAINED SAFETY-SHAPE CONCRETE BARRIERS ON CONCRETE BRIDGE DECK

Science.gov (United States)

2018-01-01

This research designed and tested a new portable concrete barrier that meets the performance of MASH TL-4 and can be used in temporary and permanent applications on bridge decks. Additionally, this new barrier system will minimize deflection, allowin...

Comparison of physical and mechanical properties of river sand concrete with quarry dust concrete

Science.gov (United States)

Opara, Hyginus E.; Eziefula, Uchechi G.; Eziefula, Bennett I.

2018-03-01

This study compared the physical and mechanical properties of river sand concrete with quarry dust concrete. The constituent materials were batched by weight. The water-cement ratio and mix ratio selected for the experimental investigation were 0.55 and 1:2:4, respectively. The specimens were cured for 7, 14, 21 and 28 days. Slump, density and compressive strength tests were carried out. The results showed that river sand concrete had greater density and compressive strength than quarry dust concrete for all curing ages. At 28 days of curing, river sand concrete exceeded the target compressive strength by 36%, whereas quarry dust concrete was less than the target compressive strength by 12%. Both river sand concrete and quarry dust concrete for the selected water/cement ratio and mix ratio are suitable for non-structural applications and lightly-loaded members where high strength is not a prerequisite.

CBP [TASK 12] experimental study of the concrete salstone two-layer system

Energy Technology Data Exchange (ETDEWEB)

Samson, Eric [SIMCO Technologies, Inc., Ville de Québec, QC (Canada); Protiere, Yannick [SIMCO Technologies, Inc., Ville de Québec, QC (Canada)

2016-11-01

This report presents the results of a study which intended to study the behavior of concrete samples placed in contact with a wasteform mixture bearing high level of sulfate in its pore solution. A setup was prepared which consisted in a wasteform poured on top of vault concrete mixes (identified as Vault 1/4 and Vault 2 mixes) cured for approximately 6 months.

Physical Characteristics of Laboratory Tested Concrete as a Substituion of Gravel on Normal Concrete

Science.gov (United States)

Butar-butar, Ronald; Suhairiani; Wijaya, Kinanti; Sebayang, Nono

2018-03-01

Concrete technology is highly potential in the field of construction for structural and non-structural construction. The amount uses of this concrete material raise the problem of solid waste in the form of concrete remaining test results in the laboratory. This waste is usually just discarded and not economically valuable. In solving the problem, this experiment was made new materials by using recycle material in the form of recycled aggregate which aims to find out the strength characteristics of the used concrete as a gravel substitution material on the normal concrete and obtain the value of the substitution composition of gravel and used concrete that can achieve the strength of concrete according to the standard. Testing of concrete characteristic is one of the requirements before starting the concrete mixture. This test using SNI method (Indonesian National Standard) with variation of comparison (used concrete : gravel) were 15: 85%, 25: 75%, 35:65%, 50:50 %, 75: 25%. The results of physical tests obtained the mud content value of the mixture gravel and used concrete is 0.03 larger than the standard of SNI 03-4142-1996 that is equal to 1.03%. so the need watering or soaking before use. The water content test results show an increase in the water content value if the composition of the used concrete increases. While the specific gravity value for variation 15: 85% until 35: 65% fulfilled the requirements of SNI 03-1969-1990. the other variasion show the specifics gravity value included on the type of light materials.

Concrete produced with recycled aggregates

Directory of Open Access Journals (Sweden)

J. J. L. Tenório

Full Text Available This paper presents the analysis of the mechanical and durable properties of recycled aggregate concrete (RAC for using in concrete. The porosity of recycled coarse aggregates is known to influence the fresh and hardened concrete properties and these properties are related to the specific mass of the recycled coarse aggregates, which directly influences the mechanical properties of the concrete. The recycled aggregates were obtained from construction and demolition wastes (CDW, which were divided into recycled sand (fine and coarse aggregates. Besides this, a recycled coarse aggregate of a specific mass with a greater density was obtained by mixing the recycled aggregates of the CDW with the recycled aggregates of concrete wastes (CW. The concrete was produced in laboratory by combining three water-cement ratios, the ratios were used in agreement with NBR 6118 for structural concretes, with each recycled coarse aggregates and recycled sand or river sand, and the reference concrete was produced with natural aggregates. It was observed that recycled aggregates can be used in concrete with properties for structural concrete. In general, the use of recycled coarse aggregate in combination with recycled sand did not provide good results; but when the less porous was used, or the recycled coarse aggregate of a specific mass with a greater density, the properties of the concrete showed better results. Some RAC reached bigger strengths than the reference concrete.

Durability of lightweight concrete : Phase I : concrete temperature study.

Science.gov (United States)

1968-08-01

This report describes a study conducted to determine the temperature gradient throughout the depth of a six inch concrete bridge deck. The bridge deck selected for study was constructed using lightweight concrete for the center spans and sand and gra...

Mechanical properties of recycled concrete with demolished waste concrete aggregate and clay brick aggregate

Science.gov (United States)

Zheng, Chaocan; Lou, Cong; Du, Geng; Li, Xiaozhen; Liu, Zhiwu; Li, Liqin

2018-06-01

This paper presents an experimental investigation on the effect of the replacement of natural coarse aggregate (NCA) with either recycled concrete aggregate (RCA) or recycled clay brick aggregate (RBA) on the compressive strengths of the hardened concrete. Two grades (C25 and C50) of concrete were investigated, which were achieved by using different water-to-cement ratios. In each grade concrete five different replacement rates, 0%, 25%, 50%, 75% and 100% were considered. In order to improve the performance of the recycled aggregates in the concrete mixes, the RCA and RBA were carefully sieved by using the optimal degradation. In this way the largest reduction in the 28-day compressive strength was found to be only 7.2% and 9.6% for C25 and C50 recycled concrete when the NCA was replaced 100% by RCA, and 11% and 13% for C25 and C50 recycled concrete when the NCA was replaced 100% by RBA. In general, the concrete with RCA has better performance than the concrete with RBA. The comparison of the present experimental results with those reported in literature for hardened concrete with either RCA or RBA demonstrates the effectiveness in improving the compressive strength by using the optimal gradation of recycled aggregates.

Material properties characterization - concrete

International Nuclear Information System (INIS)

England, G.L.; MacLeod, J.S.

1978-01-01

A review is presented of the six contributions in the SMiRT 4 conference to Session H5 on structural analysis of prestressed concrete reactor pressure vessels. These relate to short term stress-strain aspects of concrete loaded beyond the linear range in uniaxial and biaxial stress fields, to some time and temperature dependent properties of concrete at working stress levels, and to a programme of strain-gauge testing for the assessment of concrete properties. From the information discussed, it is clear that there are difficulties in determining material properties for concrete, and these are summarised. (UK)

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

OpenAIRE

Anofriev, P. G.

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...

Nanostructured silicate polymer concrete

Directory of Open Access Journals (Sweden)

Figovskiy Oleg L'vovich

2014-03-01

Full Text Available It has been known that acid-resistant concretes on the liquid glass basis have high porosity (up to 18~20 %, low strength and insufficient water resistance. Significant increasing of silicate matrix strength and density was carried out by incorporation of special liquid organic alkali-soluble silicate additives, which block superficial pores and reduce concrete shrinkage deformation. It was demonstrated that introduction of tetrafurfuryloxisilane additive sharply increases strength, durability and shock resistance of silicate polymer concrete in aggressive media. The experiments showed, that the strength and density of silicate polymer concrete increase in case of decreasing liquid glass content. The authors obtained optimal content of silicate polymer concrete, which possesses increased strength, durability, density and crack-resistance. Diffusive permeability of concrete and its chemical resistance has been investigated in various corroding media.

A historical examination of concrete

International Nuclear Information System (INIS)

Mallinson, L.G.; Li Davies, I.

1987-01-01

The requirement that concrete in radioactive waste repositories be stable physically and chemically for very long times has initiated studies of ancient and old concretes. This report is a contribution to this effort. After a description of the history of cement and concrete, the published literature relating to the analysis of old and ancient concrete is reviewed. A series of samples spanning the history of concrete has been obtained; a variety of physical and chemical techniques have been employed to characterize these samples. Reasons for survival of ancient concretes, and for durability of early, reinforced concretes are identified. Recommendations for further studies are given. 132 refs

Geochemical modelling of the evolution of a granite-concrete-water system around a repository for spent nuclear fuel

International Nuclear Information System (INIS)

Fritz, B.; Made, B.; Tardy, Y.

1988-04-01

The interactions between a granitic rock and concrete due to the natural solutions circulating around a repository for spent nuclear fuel has been simulated considering the dissolution of Ca(OH) 2 as the major source of alkalinity due to the concrete. This study follows a previous one considering the same interaction without concrete at 25, 60 and 100 deg C. The temperature range has been extended to 150 deg C. The results of the modelling are considered as following: - evolution of the water chemistry due to detected pssible chemical reactions. - minerals produced and dissolved. The calculations give mass transfers and volumic consequences (opening or closing tendencies). The conclusions of this yearly report are mainly the following: (1) the extent of the temperature range for the storage (up to 150 deg C) does not change the tendencies previously detected in the same conditions without any particular alkaline effect due to concrete dissolution, the reactions occurring tend to decrease the porosity of the rock by a sealing effect due to calcite precipitation and clays formation. (2) The effect of an alkaline concrete dissolution is clearly important, pH may reach very high values in closed system, and the volumic consequence is found in favour of an opening of the porosity, at the stage of saturation of the portlandite. This is probably an important point considering the security of natural barriers around such a repository. (authors)

304 Concretion Facility Closure Plan

International Nuclear Information System (INIS)

1991-10-01

The Hanford Site, located northwest of Richland, Washington, houses reactors, chemical-separation systems, and related facilities used for the production of special nuclear materials. The 300 Area of the Hanford Site contains reactor fuel manufacturing facilities and several research and development laboratories. Recyclable scrap uranium with Zircaloy-2 and copper silicon allo , uranium-titanium alloy, beryllium/Zircaloy-2 alloy, and Zircaloy-2 chips and fines were secured in concrete billets (7.5-gal containers) in the 304 Concretion Facility (304 Facility), located in the 300 Area. The beryllium/Zircaloy-2 alloy and Zircaloy-2 chips and fines are designated as low-level radioactive mixed waste (LLRMW) with the characteristic of ignitability. The concretion process reduced the ignitability of the fines and chips for safe storage and shipment. This process has been discontinued and the 304 Concretion Facility is now undergoing closure as defined in the Resource Conservation and Recovery Act of 1976 (RCRA) and the Washington Administrative Code (WAC) Dangerous Waste Regulations, WAC 173-303-040 (Ecology 1991). This closure plan presents a description of the facility, the history of materials and wastes managed, and the procedures that will be followed to close the 304 Facility. The strategy for closure of the 304 Facility is presented in Section 6.0

Concrete radiation shielding

International Nuclear Information System (INIS)

Kaplan, M.F.

1989-01-01

The increased use of nuclear energy has given rise to a growth in the amount of artificially produced radiation and radioactive materials. The design and construction of shielding to protect people, equipment and structures from the effects of radiation has never been more important. Experience has shown that concrete is an effective, versatile and economical material for the construction of radiation shielding. This book provides information on the principles governing the interaction of radiation with matter and on relevant nuclear physics to give the engineer an understanding of the design and construction of concrete shielding. It covers the physical, mechanical and nuclear properties of concrete; the effects of elevated temperatures and possible damage to concrete due to radiation; basic procedures for the design of concrete radiation shields and finally the special problems associated with their construction and cost. Although written primarily for engineers concerned with the design and construction of concrete shielding, the book also reviews the widely scattered data and information available on this subject and should therefore be of interest to students and those wishing to research further in this field. (author)

Radiation shielding concrete

International Nuclear Information System (INIS)

Kunishima, Shigeru.

1990-01-01

The radiation shielding concretes comprise water, cement, fine aggregates consisting of serpentines and blown mist slags, coarse aggregates consisting of serpentines and kneading materials. Since serpentines containing a relatively great amount of water of crystallization in rocks as coarse aggregates and fine aggregates, the hydrogen content in the radiation shielding concretes is increased and the neutron shielding effect is improved. In addition, since serpentines are added as the fine aggregates and blown mists slags of a great specific gravity are used, the specific gravity of the shielding concretes is increased to improve the γ-ray shielding effect. Further, by the use of the kneading material having a water reducing effect and fluidizing effect, and by the bearing effect of the spherical blown mist slags used as the fine aggregates, concrete fluidity can be increased. Accordingly, workability of the radiation shielding concretes can be improved. (T.M.)

The Fire Resistance Performance of Recycled Aggregate Concrete Columns with Different Concrete Compressive Strengths

OpenAIRE

Dong, Hongying; Cao, Wanlin; Bian, Jianhui; Zhang, Jianwei

2014-01-01

In order to ascertain the fire resistance performance of recycled aggregate concrete (RAC) components with different concrete compressive strengths, four full-scaled concrete columns were designed and tested under high temperature. Two of the four specimens were constructed by normal concrete with compressive strength ratings of C20 and C30, respectively, while the others were made from recycled coarse aggregate (RCA) concrete of C30 and C40, respectively. Identical constant axial forces were...

Reinforced concrete bridges: effects due to corrosion and concrete young modulus variation

Directory of Open Access Journals (Sweden)

P. T. C. Mendes

Full Text Available Most of the Brazilian bridges of federal road network are made of reinforced concrete and are more than 30 years old, with little information about the mechanical properties of their constitutive materials. Along the service life of these bridges much modification occurred on vehicles load and geometry and in design standard. Many of them show signs of concrete and steel deterioration and their stability conditions are unknown. With the aim of contributing to the structural evaluation of reinforced concrete bridges it was decided to analyze the stresses in reinforced concrete bridge sections to verify the effects due to reinforcement corrosion and variation of the concrete Young modulus on the stress distribution regarding several load patterns and cracking effects in a representative bridge of the Brazilian road network with different longitudinal reinforcement taxes and two concrete Young modulus, Ec and 0.5Ec, and with different percentage of reinforcement corrosion. The analysis considered two finite element models: frame and shell elements as well as solid elements. The results indicate that these variation effects are more significant in reinforcement bars than in concrete.

An historical examination of concrete

International Nuclear Information System (INIS)

Mallinson, L.G.

1986-03-01

The requirement that concrete in nuclear waste repositories be stable physically and chemically for hundreds, if not thousands, of years has initiated studies of ancient and old concretes. The history of cement and concrete is described. The oldest know concrete, from Yugoslavia, is ca. 7,500 years old. Concrete was used in many ancient civilisations, including those of Egypt, Greece and Rome. Ancient concretes were usually based upon lime, but sometimes gypsum was used. Pure lime concretes hardened by atomospheric carbonation but the Ancients, in particular the Romans, also employed hydraulic limes and discovered pozzolanas to make superior concretes which, upon hardening, contained complex cementitious hydrates including calcium-silicate-hydrate (CSH), the principal binding element in Portland cement concrete. Portland cement was not invented until 1824 or later and consists principally of calcium silicates formed by clinkerisation of a mixture of limestone and clay in carefully measured proportions. The cement sets hydraulically to form, principally, calcium hydroxide and CSH, the latter being an amorphous or semi-amorphous substance of variable composition. The published literature relating to the analysis of old and ancient cements and concretes is reviewed. A suite of samples spanning the history of concrete has been obtained. A variety of physical and chemical techniques have been employed to characterise these samples. (author)

Design of a 3-D Magnetic Mapping System to Locate Reinforcing Steel in Concrete Pavements : Technical Summary

Science.gov (United States)

2017-12-01

This report outlines the design, fabrication, and testing of a 3-D magnetic mapping system used to locate reinforcing steel in concrete pavements developed at Kansas State University (KSU) in 2006. The magnetic sensing functionality is based on the p...

Development for low-activation concrete design reducing radioactive waste

International Nuclear Information System (INIS)

Kimura, Ken-ichi; Kinno, Masaharu; Hasegawa, Akira

2008-01-01

activation cross section library and accurate estimation of major target elements in various raw materials for the concrete with width of uncertainty are necessary. So, development for low-activation concrete design reducing radioactive waste have been conducted in the project mentioned above. Detail survey of the selected aggregates and cements for the low-activation concrete are carried out and uncertain of the materials are obtained. Tons of execution experimental works for several types of low-activation concrete are conducted to categorize as conventional, high performance and boron added, with reduction rate of radioactivity to the ordinary concrete from 1/10 to 10000. Low-activation material development system and activation mapping system could calculate required quantities of target elements in certain area and boundary of the radioactivity level for shielding wall in decommissioning. These results contribute to optimize the design of low-activation concrete for reducing radioactive waste. This work is supported by a grant-in-aid of Innovative and Viable Nuclear Technology (IVNET) development project of Ministry of Economy, Trade and Industry, Japan. (author)

Early stage beneficial effects of cathodic protection in concrete structures

NARCIS (Netherlands)

Polder, R.B.; Peelen, W.H.A.; Neeft, E.A.C.; Stoop, B.T.J.

2010-01-01

Over the last 25 years, cathodic protection (CP) of reinforced concrete structures suffering from chloride induced reinforcement corrosion has shown to be successful and durable. CP current causes steel polarisation, electrochemical reactions and ion transport in the concrete. CP systems are

Novel approach to make concrete structures self-healing using porous network concrete

NARCIS (Netherlands)

Sangadji, S.; Schlangen, E.

2012-01-01

Many researchers proposed self healing mechanism using hollow fibres and or microcapsule containing a modifying agent dispersed in the concrete to prolong its service life and make it more durable. A novel self healing concrete concept is proposed in this paper by using porous network concrete

Analysis and modelling composite timber-concrete systems: Design of bridge structure according to EN

Directory of Open Access Journals (Sweden)

Manojlović Dragan

2016-01-01

Full Text Available Timber-concrete composite structures are already applied more than 80 years in engineering practice, went trought the intuitive problem solution to the fully prefabricated hybride assemblies for dry building. The development path of timber-concrete composites was always followed by extensive theoretical and experimental research, whose results were successfully implemented in practice, i.e. on the market, but till presence didn't result in modern designer's code. In expectation of new European codes for timber-concrete composites, the objective of the paper is to provide a comprehensive review of available standards provisions and recent conclusions from literature. The key issues for practical design are highlighted and ilustrated on the example of glulam composite arch bridge structure with concrete deck, according the Eurocodes.

Cracking in concrete-debonding length at the concrete/steel interface

OpenAIRE

Kjeldby, Liv Brox

2016-01-01

Investigation of the debonding length at the concrete/steel interface have been investigated based on different types of cracks in concrete. Different methods for investigation have been used in the laboratory.

Concrete

OpenAIRE

Kruse Aagaard, Anders

2015-01-01

Concrete is a component of coherent transition between a concrete base and a wooden construction. The structure is based on a quantity of investigations of the design possibilities that arise when combining digital fabrication tools and material capacities.Through tangible experiments the project discusses materiality and digitally controlled fabrications tools as direct expansions of the architect’s digital drawing and workflow. The project sees this expansion as an opportunity to connect th...

Mechanical properties of concrete containing recycled concrete aggregate (RCA) and ceramic waste as coarse aggregate replacement

Science.gov (United States)

Khalid, Faisal Sheikh; Azmi, Nurul Bazilah; Sumandi, Khairul Azwa Syafiq Mohd; Mazenan, Puteri Natasya

2017-10-01

Many construction and development activities today consume large amounts of concrete. The amount of construction waste is also increasing because of the demolition process. Much of this waste can be recycled to produce new products and increase the sustainability of construction projects. As recyclable construction wastes, concrete and ceramic can replace the natural aggregate in concrete because of their hard and strong physical properties. This research used 25%, 35%, and 45% recycled concrete aggregate (RCA) and ceramic waste as coarse aggregate in producing concrete. Several tests, such as concrete cube compression and splitting tensile tests, were also performed to determine and compare the mechanical properties of the recycled concrete with those of the normal concrete that contains 100% natural aggregate. The concrete containing 35% RCA and 35% ceramic waste showed the best properties compared with the normal concrete.

Development of a wireless MEMS multifunction sensor system and field demonstration of embedded sensors for monitoring concrete pavements, volume II

Science.gov (United States)

2016-08-01

This two-pronged study evaluated the performance of commercial off-the-shelf (COTS) micro-electromechanical sensors and systems (MEMS) embedded in concrete pavement (Final Report Volume I) and developed a wireless MEMS multifunctional sensor system f...

Optimization Design and Application of Underground Reinforced Concrete Bifurcation Pipe

Directory of Open Access Journals (Sweden)

Chao Su

2015-01-01

Full Text Available Underground reinforced concrete bifurcation pipe is an important part of conveyance structure. During construction, the workload of excavation and concrete pouring can be significantly decreased according to optimized pipe structure, and the engineering quality can be improved. This paper presents an optimization mathematical model of underground reinforced concrete bifurcation pipe structure according to real working status of several common pipe structures from real cases. Then, an optimization design system was developed based on Particle Swarm Optimization algorithm. Furthermore, take the bifurcation pipe of one hydropower station as an example: optimization analysis was conducted, and accuracy and stability of the optimization design system were verified successfully.

Effect of mineral additives on structure and properties of concrete for pavements

Science.gov (United States)

Sobol, Khrystyna; Markiv, Taras; Hunyak, Oleksii

2017-12-01

Concrete pavements is an attractive alternative to asphalt pavements because of its lower cost and higher durability. Major contribution to sustainable development can be made by partial replacement of cement in concrete pavement with supplementary cementitious materials of different nature and origin. In this paper, the effect of natural zeolite and perlite additives in complex with chemical admixtures on the structure and properties of concrete for pavement was studied. Compressive and flexural strength test was used to study the mechanical behavior of designed concrete under load. Generally, the compressive strength of both control concrete and concrete containing mineral additives levels at the later ages of hardening. The microstructure analysis of concrete with mineral additives of different nature activity showed the formation of additional amount of hydration products such as tobermorite type calcium hydrosilicate which provide self-reinforcement of hardening concrete system.

The Use of Seashell by-Products in Pervious Concrete Pavers

OpenAIRE

Dang Hanh Nguyen; Nassim Sebaibi; Mohamed Boutouil; Lydia Leleyter; Fabienne Baraud

2013-01-01

Pervious concrete is a green alternative to conventional pavements with minimal fine aggregate and a high void content. Pervious concrete allows water to infiltrate through the pavement, thereby reducing the runoff and the requirement for stormwater management systems. Seashell By-Products (SBP) are produced in an important quantity in France and are considered as waste. This work investigated to use SBP in pervious concrete and produce an even more environmentally friendly product, Pervi...

Effects on concrete from borated water and boric compounds cast into the concrete

International Nuclear Information System (INIS)

Fagerlund, Goeran

2010-06-01

A study has been made of the effects on concrete of its exposure to external water containing boric acid, and the effects on concrete of boric compounds cast into the concrete during its manufacture. According to information in literature boric acid is a weak Lewis acid that has no effect on concrete. Reaction between calcium hydroxide existing in concrete and boric acid might occur at the concrete surface. The reaction product formed (calcium-metaboritehexahydrate) has lower solubility than calcium hydroxide itself. Therefore, the reaction is reasonably harmless. Accelerated and non-accelerated test methods exist by which quantitative information on the effect of boric acid can be obtained. The test principles are described. Boron-containing compounds might be mixed into concrete in order to increase its resistance to neutron radiation. Pure boron minerals, as well as boron-containing residual materials from processing of natural boron minerals, might be used. Concrete might be affected with regard to the following properties: - Workability of the fresh concrete; - Stiffening and hardening of the concrete; - Strength (compression, tension); - Deformation (E-modulus, creep); - Durability (chemical, steel corrosion. Information in literature indicates that the hardening process might be severely affected also when rather small amounts of certain boron-containing materials are used. The effect seems to be small, or none, however, if materials with low solubility are used. The effect on workability seems to be marginal. Test methods exist by which it is practical possible to develop acceptable concrete recipes. The effects on mechanical properties are not well clarified by research. However, effects seem to be small when boron materials with low solubility are used. In one study, in which part of the cement was replaced by a boron containing colemanite waste, it was found that the E-modulus was very much reduced. The significance of this result is unclear. The

Electrokinetic decontamination of concrete

International Nuclear Information System (INIS)

Lomasney, H.L.; SenGupta, A.K.; Yachmenev, V.

1996-01-01

ELECTROSORB Electrokinetic Extraction Technology, developed by ISOTRON Corp., offers a cost-effective approach to treating contaminated concrete. Heavy metals/radionuclides trapped in concrete can be extracted using this process if they are chemically solubilized; solubilizers used are citric acid alone and a mixture of citric and nitric acids. A DC electric field is applied across the contaminated concrete to electrokinetically transport the solubilized contaminants from the concrete pores to a collector on the concrete surface. The collector is an extraction pad laid on the surface. The pad provides confinement for a planar electrode and solubilizer solution; it is operated under a vacuum to hold the pad against the concrete surface. Operation requires little attendance, reducing the workers' health hazards. The process incorporates a mechanism for recycling the solubilizer solution. A field demonstration of the process took place in Building 21 of DOE's Mound facility in Miamisburg, OH, over 12 days in June 1996. The thorium species present in this building's concrete floors included ThO 2 and thorium oxalate. The nitric acid was found to facilitate Th extraction

Feasibility study of a concrete plug made of low pH concrete

Energy Technology Data Exchange (ETDEWEB)

Dahlstroem, Lars-Olof; Magnusson, Jonas (NCC Engineering (Sweden)); Gueorguiev, Ginko; Johansson, Morgan (Reinertsen Sverige AB, Goeteborg (Sweden))

2009-09-15

In this report a concrete plug, used as a barrier between the deposition tunnels and the access tunnel, is investigated. The objectives of the work is to see whether it is possible to use low pH concrete for the plug and whether it can be designed without using reinforcement. The requirements set on the plug are that the water leakage through it should be small enough and that the concrete stresses are limited to a value valid for the concrete used. A modified geometry of the plug is proposed, which makes it possible to use it as a general solution in all deposition tunnels. Material properties of a low pH concrete (B200) determined by CBI have been used. Loads considered in the study is the pressure from water and swelling, the temperature change in the rock and plug due to heat development from nuclear fuel stored in nearby copper canisters, pre-stressing in the plug due to cooling during construction and the shrinkage of concrete in the plug. Two-dimensional, axis-symmetric finite element analyses, assuming linear elastic material behaviour in rock and concrete where contact friction between concrete and rock is taken into consideration, have been used to study the structural response of the plug. A total of 48 main load combinations, consisting of 8 different load scenarios and 6 material combinations, have been used. It is found that the concrete plug will not remain uncracked when subjected to the loads studied but that it, nevertheless, is possible to achieve an unreinforced concrete plug that satisfies the requirements set up. The minimum size of the concrete compressed zone will be 0.5 m, resulting in a water leakage through the plug determined to be lower than the requirement of 0.01 l/min set up in this study. Further, the maximum compressive stresses of interest are 33 MPa and the maximum displacement in the plug is about 3 mm, which are deemed to be satisfactorily. Consequently, it is concluded that it seems possible to use low pH concrete for the plug

Modified pavement cement concrete

Science.gov (United States)

Botsman, L. N.; Ageeva, M. S.; Botsman, A. N.; Shapovalov, S. M.

2018-03-01

The paper suggests design principles of pavement cement concrete, which covers optimization of compositions and structures at the stage of mixture components selection due to the use of plasticizing agents and air-retaining substances that increase the viability of a concrete mixture. It also demonstrates advisability of using plasticizing agents together with air-retaining substances when developing pavement concrete compositions, which provides for the improvement of physical and mechanical properties of concrete and the reduction of cement binding agent consumption thus preserving strength indicators. The paper shows dependences of the main physical-mechanical parameters of concrete on cement consumption, a type and amount of additives.

The Fire Resistance Performance of Recycled Aggregate Concrete Columns with Different Concrete Compressive Strengths.

Science.gov (United States)

Dong, Hongying; Cao, Wanlin; Bian, Jianhui; Zhang, Jianwei

2014-12-08

In order to ascertain the fire resistance performance of recycled aggregate concrete (RAC) components with different concrete compressive strengths, four full-scaled concrete columns were designed and tested under high temperature. Two of the four specimens were constructed by normal concrete with compressive strength ratings of C20 and C30, respectively, while the others were made from recycled coarse aggregate (RCA) concrete of C30 and C40, respectively. Identical constant axial forces were applied to specimens while being subjected to simulated building fire conditions in a laboratory furnace. Several parameters from the experimental results were comparatively analyzed, including the temperature change, vertical displacement, lateral deflection, fire endurance, and failure characteristics of specimens. The temperature field of specimens was simulated with ABAQUS Software (ABAQUS Inc., Provindence, RI, USA) and the results agreed quite well with those from the experiments. Results show that the rate of heat transfer from the surface to the interior of the column increases with the increase of the concrete's compressive strength for both RAC columns and normal concrete columns. Under the same initial axial force ratio, for columns with the same cross section, those with lower concrete compressive strengths demonstrate better fire resistance performance. The fire resistance performance of RAC columns is better than that of normal concrete columns, with the same concrete compressive strength.

Lunar concrete for construction

Science.gov (United States)

Cullingford, Hatice S.; Keller, M. Dean

1988-01-01

Feasibility of using concrete for lunar-base construction has been discussed recently without relevant data for the effects of vacuum on concrete. Experimental studies performed earlier at Los Alamos have shown that concrete is stable in vacuum with no deterioration of its quality as measured by the compressive strength. Various considerations of using concrete successfully on the moon are provided in this paper along with specific conclusions from the existing data base.

Concrete Plant Operations Optimization Using Combined Simulation and Genetic Algorithms

NARCIS (Netherlands)

Cao, Ming; Lu, Ming; Zhang, Jian-Ping

2004-01-01

This work presents a new approach for concrete plant operations optimization by combining a ready mixed concrete (RMC) production simulation tool (called HKCONSIM) with a genetic algorithm (GA) based optimization procedure. A revamped HKCONSIM computer system can be used to automate the simulation

Structural-functional integrated concrete with macro-encapsulated inorganic PCM

Science.gov (United States)

Mohseni, Ehsan; Tang, Waiching; Wang, Zhiyu

2017-09-01

Over the last few years the application of thermal energy storage system incorporating phase change materials (PCMs) to foster productivity and efficiency of buildings energy has grown rapidly. In this study, a structural-functional integrated concrete was developed using macro-encapsulated PCM-lightweight aggregate (LWA) as partial replacement (25 and 50% by volume) of coarse aggregate in control concrete. The PCM-LWA was prepared by incorporation of an inorganic PCM into porous LWAs through vacuum impregnation. The mechanical and thermal performance of PCM-LWA concrete were studied. The test results revealed that though the compressive strength of concrete with PCM-LWA was lower than the control concrete, but ranged from 22.02 MPa to 42.88 MPa which above the minimum strength requirement for structural application. The thermal performance test indicated that macro-encapsulated PCM-LWA has underwent the phase change transition reducing the indoor temperature.

How to transform an asphalt concrete pavement into a solar turbine

International Nuclear Information System (INIS)

García, Alvaro; Partl, Manfred N.

2014-01-01

Highlights: • We create a system for harvesting energy from asphalt concrete. • We create an artificial porosity in the asphalt concrete. • We connect a chimney to this porosity. • Differences in temperature produce an air flow. • This air flow serves also for cooling down the pavement. - Abstract: Asphalt concrete can absorb a considerable amount of the incident solar radiation. For this reason asphalt roads could be used as solar collectors. There have been different attempts to achieve this goal. All of them have been done by integrating pipes conducting liquid, through the structure of the asphalt concrete. The problem of this system is that all pipes need to be interconnected: if one is broken, the liquid will come out and damage the asphalt concrete. To overcome these limitations, in this article, an alternative concept is proposed:parallel air conduits, where air can circulate will be integrated in the pavement structure. The idea is to connect these artificial pore volumes in the pavement to an updraft or to a downdraft chimney. Differences of temperature between the pavement and the environment can be used to create an air flow, which would allow wind turbines to produce an amount of energy and that would cool the pavement down in summer or even warm it up in winter. To demonstrate that this is possible, an asphalt concrete prototype has been created and basics calculations on the parameters affecting the system have been done. It has been found that different temperatures, volumes of air inside the asphalt and the difference of temperature between the asphalt concrete and the environment are critical to maximize the air flow through the pavement. Moreover, it has been found that this system can be also used to reduce the heat island effect

Concrete-Design

Directory of Open Access Journals (Sweden)

Leczovics Péter

2014-12-01

Full Text Available Present paper introduces a new interpretation of concrete, demonstrating some extreme possibilities of this rigid material such as a design element. In the first part a brief overview of the previous achievements are shown. The second part of this paper focuses on the relationship between concrete and fashion.

ESEARCH OF THE PROPERTIES OF THE SELF-COMPACTED CONCRETE OVER TIME

Directory of Open Access Journals (Sweden)

S. Bugayevskiy

2017-12-01

Full Text Available Concrete mixture is examined as a complex multicomponent system that becomes a single unit and can be studied as a physical unity with certain rheological, physical and mechanical properties. Studying the change of properties of self-compacted concrete over time, as well as the effect of two-phasic introduction of super-plasticizer on properties of concrete mixture are presented in this article.

PRIMARY STAGE OF PAKIS-STEM-BLOCK SYSTEM AS THERMAL PROTECTIVE TO FLAT BARE CONCRETE ROOFTOP IN TROPICAL CLIMATE OF SURABAYA

Directory of Open Access Journals (Sweden)

Danny Santoso Mintorogo

2011-07-01

Full Text Available In the era of global warming and increasing urban heat island condition, flat concrete deck on shop-houses may be less sustainable to handle the excessive solar heat radiation impacts on the roof surfaces. Innovative alternative roofing system is needed to manage heat radiation that will lead to sustainable factors likes energy savings, less energy body used on the roofing materials, and provide comprehensive environmental friendly roof system. This paper discusses about particular environmental friendly materials such as “Pakis-Stem Blocks” system is a good thermal resistant to absorb the solar sun heat and provide natural cooling through convective-wind without adding substantial loads to the roof structures. “Pakis-stem blocks” are easier, cheaper and more valuable than other sub-structure roofing materials as thermal resistant layer on flat bare concrete deck besides green roofing systems.

Finite element analysis of degraded concrete structures - Workshop proceedings

International Nuclear Information System (INIS)

1999-09-01

This workshop is related to the finite element analysis of degraded concrete structures. It is composed of three sessions. The first session (which title is: the use of finite element analysis in safety assessments) comprises six papers which titles are: Historical Development of Concrete Finite Element Modeling for Safety Evaluation of Accident-Challenged and Aging Concrete Structures; Experience with Finite Element Methods for Safety Assessments in Switzerland; Stress State Analysis of the Ignalina NPP Confinement System; Prestressed Containment: Behaviour when Concrete Cracking is Modelled; Application of FEA for Design and Support of NPP Containment in Russia; Verification Problems of Nuclear Installations Safety Software of Strength Analysis (NISS SA). The second session (title: concrete containment structures under accident loads) comprises seven papers which titles are: Two Application Examples of Concrete Containment Structures under Accident Load Conditions Using Finite Element Analysis; What Kind of Prediction for Leak rates for Nuclear Power Plant Containments in Accidental Conditions; Influence of Different Hypotheses Used in Numerical Models for Concrete At Elevated Temperatures on the Predicted Behaviour of NPP Core Catchers Under Severe Accident Conditions; Observations on the Constitutive Modeling of Concrete Under Multi-Axial States at Elevated Temperatures; Analyses of a Reinforced Concrete Containment with Liner Corrosion Damage; Program of Containment Concrete Control During Operation for the Temelin Nuclear Power Plant; Static Limit Load of a Deteriorated Hyperbolic Cooling Tower. The third session (concrete structures under extreme environmental load) comprised five papers which titles are: Shear Transfer Mechanism of RC Plates After Cracking; Seismic Back Calculation of an Auxiliary Building of the Nuclear Power Plant Muehleberg, Switzerland; Seismic Behaviour of Slightly Reinforced Shear Wall Structures; FE Analysis of Degraded Concrete

Concrete spent fuel storage casks dose rates

International Nuclear Information System (INIS)

Bace, M.; Jecmenica, R.; Trontl, K.

1998-01-01

Our intention was to model a series of concrete storage casks based on TranStor system storage cask VSC-24, and calculate the dose rates at the surface of the casks as a function of extended burnup and a prolonged cooling time. All of the modeled casks have been filled with the original multi-assembly sealed basket. The thickness of the concrete shield has been varied. A series of dose rate calculations for different burnup and cooling time values have been performed. The results of the calculations show rather conservative original design of the VSC-24 system, considering only the dose rate values, and appropriate design considering heat rejection.(author)

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

International Nuclear Information System (INIS)

Zhao Yongguang

2013-01-01

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)

Effect of mineral additives on structure and properties of concrete for pavements

Directory of Open Access Journals (Sweden)

Sobol Khrystyna

2017-12-01

Full Text Available Concrete pavements is an attractive alternative to asphalt pavements because of its lower cost and higher durability. Major contribution to sustainable development can be made by partial replacement of cement in concrete pavement with supplementary cementitious materials of different nature and origin. In this paper, the effect of natural zeolite and perlite additives in complex with chemical admixtures on the structure and properties of concrete for pavement was studied. Compressive and flexural strength test was used to study the mechanical behavior of designed concrete under load. Generally, the compressive strength of both control concrete and concrete containing mineral additives levels at the later ages of hardening. The microstructure analysis of concrete with mineral additives of different nature activity showed the formation of additional amount of hydration products such as tobermorite type calcium hydrosilicate which provide self-reinforcement of hardening concrete system.

Concrete material characterization reinforced concrete tank structure Multi-Function Waste Tank Facility

International Nuclear Information System (INIS)

Winkel, B.V.

1995-01-01

The purpose of this report is to document the Multi-Function Waste Tank Facility (MWTF) Project position on the concrete mechanical properties needed to perform design/analysis calculations for the MWTF secondary concrete structure. This report provides a position on MWTF concrete properties for the Title 1 and Title 2 calculations. The scope of the report is limited to mechanical properties and does not include the thermophysical properties of concrete needed to perform heat transfer calculations. In the 1970's, a comprehensive series of tests were performed at Construction Technology Laboratories (CTL) on two different Hanford concrete mix designs. Statistical correlations of the CTL data were later generated by Pacific Northwest Laboratories (PNL). These test results and property correlations have been utilized in various design/analysis efforts of Hanford waste tanks. However, due to changes in the concrete design mix and the lower range of MWTF operating temperatures, plus uncertainties in the CTL data and PNL correlations, it was prudent to evaluate the CTL data base and PNL correlations, relative to the MWTF application, and develop a defendable position. The CTL test program for Hanford concrete involved two different mix designs: a 3 kip/in 2 mix and a 4.5 kip/in 2 mix. The proposed 28-day design strength for the MWTF tanks is 5 kip/in 2 . In addition to this design strength difference, there are also differences between the CTL and MWTF mix design details. Also of interest, are the appropriate application of the MWTF concrete properties in performing calculations demonstrating ACI Code compliance. Mix design details and ACI Code issues are addressed in Sections 3.0 and 5.0, respectively. The CTL test program and PNL data correlations focused on a temperature range of 250 to 450 F. The temperature range of interest for the MWTF tank concrete application is 70 to 200 F

Effect of concrete strength gradation to the compressive strength of graded concrete, a numerical approach

Science.gov (United States)

Pratama, M. Mirza Abdillah; Aylie, Han; Gan, Buntara Sthenly; Umniati, B. Sri; Risdanareni, Puput; Fauziyah, Shifa

2017-09-01

Concrete casting, compacting method, and characteristic of the concrete material determine the performance of concrete as building element due to the material uniformity issue. Previous studies show that gradation in strength exists on building member by nature and negatively influence the load carrying capacity of the member. A pilot research had modeled the concrete gradation in strength with controllable variable and observed that the weakest material determines the strength of graded concrete through uniaxial compressive loading test. This research intends to confirm the recent finding by a numerical approach with extensive variables of strength disparity. The finite element analysis was conducted using the Strand7 nonlinear program. The results displayed that the increase of strength disparity in graded concrete models leads to the slight reduction of models strength. A substantial difference in displacement response is encountered on the models for the small disparity of concrete strength. However, the higher strength of concrete mix in the graded concrete models contributes to the rise of material stiffness that provides a beneficial purpose for serviceability of building members.

Deterioration of Concrete Structures

DEFF Research Database (Denmark)

Thoft-Christensen, Palle

Chloride ingress is a common cause of deterioration of reinforced concrete bridges. Concrete may be exposed to chloride by seawater or de-icing salts. The chloride initiates corrosion of the reinforcement, which through expansion disrupts the concrete. In addition, the corrosion reduces the cross...

Life Cycle Assessment of Concrete

Energy Technology Data Exchange (ETDEWEB)

Sjunnesson, Jeannette

2005-09-15

This is an environmental study on concrete that follows the standard protocol of life cycle assessment (LCA). The study is done for two types of concrete, ordinary and frost-resistant concrete, and has an extra focus on the superplasticizers used as admixtures. The utilization phase is not included in this study since the type of construction for which the concrete is used is not defined and the concrete is assumed to be inert during this phase. The results show that it is the production of the raw material and the transports involved in the life cycle of concrete that are the main contributors to the total environmental load. The one single step in the raw material production that has the highest impact is the production of cement. Within the transportation operations the transportation of concrete is the largest contributor, followed by the transportation of the cement. The environmental impact of frost-resistant concrete is between 24-41 % higher than that of ordinary concrete due to its higher content of cement. Superplasticizers contribute with approximately 0.4-10.4 % of the total environmental impact of concrete, the least to the global warming potential (GWP) and the most to the photochemical ozone creation potential (POCP). Also the toxicity of the superplasticizers is investigated and the conclusion is that the low amount of leakage of superplasticizers from concrete leads to a low risk for the environment and for humans.

Performance of Waterless Concrete

Science.gov (United States)

Toutanji, Houssam; Evans, Steve; Grugel, Richard N.

2010-01-01

The development of permanent lunar bases is constrained by performance of construction materials and availability of in-situ resources. Concrete seems a suitable construction material for the lunar environment, but water, one of its major components, is an extremely scarce resource on the Moon. This study explores an alternative to hydraulic concrete by replacing the binding mix of concrete (cement and water) with sulfur. Sulfur is a volatile element on the lunar surface that can be extracted from lunar soils by heating. Sulfur concrete mixes were prepared to investigate the effect of extreme environmental conditions on the properties of sulfur concrete. A hypervelocity impact test was conducted, having as its target a 5-cm cubic sample of sulfur concrete. This item consisted of JSC-1 lunar regolith simulant (65%) and sulfur (35%). The sample was placed in the MSFC Impact Test Facility s Micro Light Gas Gun target chamber, and was struck by a 1-mm diameter (1.4e-03 g) aluminum projectile at 5.85 km/s. In addition, HZTERN code, provided by NASA was used to study the effectiveness of sulfur concrete when subjected to space radiation.

Steel fiber reinforced concrete

International Nuclear Information System (INIS)

Baloch, S.U.

2005-01-01

Steel-Fiber Reinforced Concrete is constructed by adding short fibers of small cross-sectional size .to the fresh concrete. These fibers reinforce the concrete in all directions, as they are randomly oriented. The improved mechanical properties of concrete include ductility, impact-resistance, compressive, tensile and flexural strength and abrasion-resistance. These uniqlte properties of the fiber- reinforcement can be exploited to great advantage in concrete structural members containing both conventional bar-reinforcement and steel fibers. The improvements in mechanical properties of cementitious materials resulting from steel-fiber reinforcement depend on the type, geometry, volume fraction and material-properties of fibers, the matrix mix proportions and the fiber-matrix interfacial bond characteristics. Effects of steel fibers on the mechanical properties of concrete have been investigated in this paper through a comprehensive testing-programme, by varying the fiber volume fraction and the aspect-ratio (Lid) of fibers. Significant improvements are observed in compressive, tensile, flexural strength and impact-resistance of concrete, accompanied by marked improvement in ductility. optimum fiber-volume fraction and aspect-ratio of steel fibers is identified. Test results are analyzed in details and relevant conclusions drawn. The research is finally concluded with future research needs. (author)

The suitability of concrete using recycled aggregates (RAs) for high-performance concrete (HPC)

OpenAIRE

Torgal, Fernando Pacheco; Ding, Y.; Miraldo, Sérgio; Abdollahnejad, Zahra; Labrincha, J. A.

2013-01-01

Most studies related to concrete made with recycled aggregates (RA) use uncontaminated aggregates produced in the laboratory, revealing the potential to re-use as much as 100%. However, industrially produced RA contain a certain level of impurities that can be deleterious for Portland cement concrete, thus making it difficult for the concrete industry to use such investigations unless uncontaminated RA are used. This chapter reviews current knowledge on concrete made with RA, with a focus on ...

Shear crack propagation in MBC strengthened concrete beams”

DEFF Research Database (Denmark)

Täljsten, Björn; Blanksvärd, Thomas; Carolin, Anders

2008-01-01

thermal compatibility to the base concrete and are often sensitive to the surface nature and surrounding temperature. By using mineral based composites (MBC) some of these challenges can be overcome. MBC refers here to a cementitious bonding agent and a carbon FRP grid. This paper is a part of an ongoing......Repair and upgrading existing concrete structures using FRPs and an epoxy adhesive as the bonding agent has some disadvantages when it comes to compatibility to the base concrete. Epoxies are often restricted by regulations of use, have low permeability which may create freeze/thaw problems, poor...... study of MBC systems. Emphasis is placed on the cracking behavior of the MBC system used for shear strengthening of RC beams. Traditional foil strain gauges and photometric measurements have been used for monitoring of the cracking behavior. In this study it is shown that the use of mineral based shear...

Cost Effectiveness of Precast Reinforced Concrete Roof Slabs

Science.gov (United States)

Parskiy, N. D.; Molodtsov, M. V.; Molodtsova, V. E.

2017-11-01

Engineers always seek to free interior space from intermediate supporting elements. Nowadays plants, being at the forefront of technology, produce a new generation of exclusive patented prefabricated reinforced concrete elements with a high load-bearing capacity, excellent heat resistance characteristics combined with the aesthetics and beauty. It is a system of Seagull Gabbiano prestressed roof slabs for the spans of 12m - 40m. The article shows the advantages of the Seagull slabs over conventional precast reinforced concrete and metal roof trusses. It also gives the analysis of the technical and economic indices of design and construction of a building with the Seagull slabs depending on the size of spans to cover. The use of structural systems with increased spans allows for the modern buildings and structures of prefabricated reinforced concrete with enhanced functionality and aesthetics alongside with a wide range of planning solutions.

1st International Conference on Calcined Clays for Sustainable Concrete

CERN Document Server

Favier, Aurélie

2015-01-01

This volume focuses on research and practical issues linked to Calcined Clays for Sustainable Concrete. The main subjects are geology of clays, hydration and performance of blended systems with calcined clays, alkali activated binders, economic and environmental impacts of the use of calcined clays in cement based materials. Topics addressed in this book include the influence of processing on reactivity of calcined clays, influence of clay mineralogy on reactivity, geology of clay deposits, Portland-calcined clay systems, hydration, durability, performance, Portland-calcined clay-limestone systems, hydration, durability, performance, calcined clay-alkali systems, life cycle analysis, economics and environmental impact of use of calcined clays in cement and concrete, and field applications. This book compiles the different contributions of the 1st International Conference on Calcined Clays for Sustainable Concrete, which took place in Lausanne, Switzerland, June, 23-25, 2015.The papers present the latest  res...

Abrasive water jet cutting technique for biological shield concrete dismantlement

International Nuclear Information System (INIS)

Konno, T.; Narazaki, T.; Yokota, M.; Yoshida, H.; Miura, M.; Miyazaki, Y.

1987-01-01

The Japan Atomic Energy Research Institute (JAERI) is developing the abrasive-water jet cutting system to be applied to dismantling the biological shield walls of the JPDR as a part of the reactor dismantling technology development project. This is a total system for dismantling highly activated concrete. The concrete biological shield wall is cut into blocks by driving the abrasive-water jet nozzle, which is operated with a remote, automated control system. In this system, the concrete blocks are removed to a container, while the slurry and dust/mist which are generated during cutting are collected and treated, both automatically. It is a very practical method and will quite probably by used for actual dismantling of commercial power reactors in the future because it can minimize workers' exposure to radioactivity during dismantling, contributes to preventing diffusion of radiation, and reduces the volume of contaminated secondary waste

Retrofitting of Reinforced Concrete Beams using Reactive Powder Concrete (RPC)

Science.gov (United States)

Karthik, S.; Sundaravadivelu, Karthik

2017-07-01

Strengthening of existing damaged structures is one of the leading studies in civil engineering. The purpose of retrofitting is to structurally treat the member with an aim to restore the structure to its original strength. The focus of this project is to study the behaviour of damaged Reinforced Concrete beam retrofitted with Reactive Powder Concrete (RPC) Overlay. Reinforced concrete beams of length 1200 mm, width 100 mm and depth 200 mm were casted with M30 grade of concrete in the laboratory and cured for 28 days. One beam is taken as control and are tested under two point loading to find out ultimate load. Remaining beams are subjected to 90 % ultimate load of control beams. The partially damaged beams are retrofitted with Reactive Powder Concrete Overlay at the full tension face of the beam and side overlay depends upon the respectable retrofitting techniques with 10 mm and 20 mm thick layer to find optimum. Materials like steel fibres are added to enhance the ductility by eliminating coarse particle for homogeneity of the structure. Finally, the modes of failure for retrofitted beams are analysed experimentally under two point loading & compared the results with Control beam.

Steel-concrete bond model for the simulation of reinforced concrete structures

International Nuclear Information System (INIS)

Mang, Chetra

2015-01-01

Reinforced concrete structure behavior can be extremely complex in the case of exceeding the cracking threshold. The composite characteristics of reinforced concrete structure should be finely presented especially in the distribution stress zone between steel-concrete at their interface. In order to compute the industrial structures, a perfect relation hypothesis between steel and concrete is supposed in which the complex phenomenon of the two-material relation is not taken into account. On the other hand, this perfect relation is unable to predict the significant disorders, the repartition, and the distribution of the cracks, which is directly linked to the steel. In literature, several numerical methods are proposed in order to finely study the concrete-steel bond behavior, but these methods give many difficulties in computing complex structures in 3D. With the results obtained in the thesis framework of Torre-Casanova (2012), the new concrete-steel bond model has been developed to improve performances (iteration numbers and computational time) and the representation (cyclic behavior) of the initial one. The new model has been verified with analytical solution of steel-concrete tie and validated with the experimental results. The new model is equally tested with the structural scale to compute the shear wall behavior in the French national project (CEOS.fr) under monotonic load. Because of the numerical difficulty in post-processing the crack opening in the complex crack formation, a new crack opening method is also developed. This method consists of using the discontinuity of relative displacement to detect the crack position or using the slip sign change between concrete-steel. The simulation-experiment comparison gives validation of not only the new concrete-steel bond model but also the new crack post-processing method. Finally, the cyclic behavior of the bond law with the non-reduced envelope is adopted and integrated in the new bond model in order to take

Nanophase modified fly ash concrete with superior concrete properties, durability and biofouling resistance for seawater applications

International Nuclear Information System (INIS)

Vishwakarma, Vinita; Sudha, U.; Ramachandran, D.; George, R.P.; Kamachi Mudali, U.; Kalpana Kumari; Preetha, R.; Pillai, C.S.

2015-01-01

There are many concrete structures in the cooling water system of nuclear power plants that are exposed to seawater in the form of tanks, pillars and reservoirs. These structures come in contact with aggressive chlorides and acid producing microbes and deteriorate by chemical and biological factors. Recently fly ash (FA) concrete has emerged exhibiting excellent degradation resistance in seawater environments. However some disadvantages are reported like lesser early strength, higher carbonation and calcium leaching. This work attempted to modify FA concrete by adding nanoparticles of TiO 2 and CaCO 3 for increased strength and degradation resistance. Four types of concrete and mortar mix namely fly ash concrete (FA), FA with 2% TiO 2 nanoparticles (FAT), FA with 2% CaCO 3 nanoparticles and FA with 2% TiO 2 : CaCO 3 nanoparticles were cast and immersed in seawater for a year. Thermal analysis and Differential thermal analysis (TG-DTA) analysis was done before exposing in sea water to know the changes in the physical properties of the specimens at higher temperature. Strength and durability were evaluated using parameters like compressive strength, split tensile test, Rapid chloride permeability test (RCPT), carbonation test and pH degradation. Detailed biofilm characterizations were attempted using microbiological and molecular biology tools to study the antibacterial properties. Calcium leaching and sulfate attack studies were carried out by laboratory exposure studies. Using field emission scanning electron microscopy (FESEM) and X-ray diffraction technique (XRD), microstructural properties and chemical phases were identified. All the nanophase modified FA specimens showed superior properties compared to FA concrete with respect to strength, carbonation depth, calcium leaching and antibacterial activity. Results are discussed in detail in the paper. (author)

X-ray test system for detection of under grounds in concrete

International Nuclear Information System (INIS)

Katou, Kiyoshi

1997-01-01

Previously the durability of concrete constructions was thought to be nearly semi-permanent if its strength was secured, but thereafter the significance of diagnosis for its durability has been paid considerable attention as the buildings after ca. 1955 were constructed according to the idea of scrap and build. In addition to the conventional non-destructive methods, development of another method became necessary and roentgenoscopic imaging method has been used to examine the intra-concrete conditions. Here, a radiographic method was introduced to determine the positioning of materials buried in a concrete building. This method was not appropriate to examine a wide area from the viewpoint of working efficiency and its cost. Therefore, the examination must be done after selecting a restricted site to test. For an examination of a wide area, a combined use with laser light survey was necessary. The roentgenographic method is often used for examinations for the kind of reinforcing rods and their distributions. Presently, this method is used for diagnosing the durability for static constructions. (M.N.)

Shape Effect of Electrochemical Chloride Extraction in Structural Reinforced Concrete Elements Using a New Cement-Based Anodic System

Directory of Open Access Journals (Sweden)

Jesús Carmona

2015-05-01

Full Text Available This article shows the research carried out by the authors focused on how the shape of structural reinforced concrete elements treated with electrochemical chloride extraction can affect the efficiency of this process. Assuming the current use of different anode systems, the present study considers the comparison of results between conventional anodes based on Ti-RuO2 wire mesh and a cement-based anodic system such as a paste of graphite-cement. Reinforced concrete elements of a meter length were molded to serve as laboratory specimens, to closely represent authentic structural supports, with circular and rectangular sections. Results confirm almost equal performances for both types of anode systems when electrochemical chloride extraction is applied to isotropic structural elements. In the case of anisotropic ones, such as rectangular sections with no uniformly distributed rebar, differences in electrical flow density were detected during the treatment. Those differences were more extreme for Ti-RuO2 mesh anode system. This particular shape effect is evidenced by obtaining the efficiencies of electrochemical chloride extraction in different points of specimens.

Shape Effect of Electrochemical Chloride Extraction in Structural Reinforced Concrete Elements Using a New Cement-Based Anodic System

Science.gov (United States)

Carmona, Jesús; Climent, Miguel-Ángel; Antón, Carlos; de Vera, Guillem; Garcés, Pedro

2015-01-01

This article shows the research carried out by the authors focused on how the shape of structural reinforced concrete elements treated with electrochemical chloride extraction can affect the efficiency of this process. Assuming the current use of different anode systems, the present study considers the comparison of results between conventional anodes based on Ti-RuO2 wire mesh and a cement-based anodic system such as a paste of graphite-cement. Reinforced concrete elements of a meter length were molded to serve as laboratory specimens, to closely represent authentic structural supports, with circular and rectangular sections. Results confirm almost equal performances for both types of anode systems when electrochemical chloride extraction is applied to isotropic structural elements. In the case of anisotropic ones, such as rectangular sections with no uniformly distributed rebar, differences in electrical flow density were detected during the treatment. Those differences were more extreme for Ti-RuO2 mesh anode system. This particular shape effect is evidenced by obtaining the efficiencies of electrochemical chloride extraction in different points of specimens.

High temperature helium test rig with prestressed concrete pressure vessel

International Nuclear Information System (INIS)

Schmidl, H.

1975-10-01

The report gives a short description of the joint project prestressed concrete vessel-helium test station as there is the building up of the concrete structure, the system of instrumentation, the data processing, the development of the helium components as well as the testing programs. (author)

Application of concrete filled steel bearing wall to inner concrete structure fro PWR nuclear power plant

International Nuclear Information System (INIS)

Sekimoto, Hisashi; Tanaka, Mamoru; Inoue, Kunio; Fukihara, Masaaki; Akiyama, Hiroshi.

1992-01-01

'Concrete filled steel bearing wall', applied to the inner concrete structure for PWR nuclear power plant, was developed for rationalization of construction procedure at site. It was concluded through preliminary studies that this new type of wall, where concrete is placed between steel plates, is best suited for the strength members of the above structure, due to the high strength and ductility of surface steel plates and the confinement effect of filled concrete. To verify the behavior from the elastic range to the inelastic range, the ultimate strength and the failure mechanism, and to clarify experimentally the structural integrity of the inner concrete structure, which was composed of a concrete filled steel bearing wall, against seismic lateral loads, horizontal loading tests using a 1/10th scale model of the inner concrete structure for PWR nuclear power plant were conducted. As a result of the tests, the inner concrete structure composed of a concrete filled steel bearing wall appeared to have a larger load carrying capacity and a higher ductility as compared with that composed of a reinforced concrete wall. (author)

Image analysis for the detection and quantification of concrete bugholes in a tunnel lining

Directory of Open Access Journals (Sweden)

Isamu Yoshitake

2018-06-01

Full Text Available A measurement and quantification system for concrete bugholes (surface air voids on sidewalls was developed to quantify the surface quality of tunnel-lining concrete. The developed system uses and evaluates red/green/blue values of color images taken by a commercial digital still camera. A comparative test shows that the developed system has higher accuracy than image analyses using thresholding and can estimate bugholes with accuracy almost equal to that of a detailed visual inspection. The results confirm that even small bugholes (<1 mm can be detected in color image analysis, whereas such bugholes are hardly detected in the detailed visual survey. In addition, color image analysis improves the calculations of the area of multiple bugholes distributed randomly over a concrete surface. Fundamental tests employing image analysis demonstrate that the prevalence of bugholes increases with an increase in the negative angle of the concrete form and a decrease in concrete workability. The system is applicable to the quantitative evaluation of a concrete surface having visible and invisible bugholes. Results indicate that the developed color image analysis can contribute to the reasonable and appropriate evaluation of bugholes and replace a detailed survey that requires much human resource and has a long inspection time. Keywords: Bughole, Image analysis, Surface quality, Tunnel lining concrete, Laboratory test, Inspection

Fracture Behavior and Properties of Functionally Graded Fiber-Reinforced Concrete

International Nuclear Information System (INIS)

Roesler, Jeffery; Bordelon, Amanda; Gaedicke, Cristian; Park, Kyoungsoo; Paulino, Glaucio

2008-01-01

In concrete pavements, a single concrete mixture design is selected to resist mechanical loading without attempting to adversely affect the concrete pavement shrinkage, ride quality, or noise attenuation. An alternative approach is to design distinct layers within the concrete pavement surface which have specific functions thus achieving higher performance at a lower cost. The objective of this research was to address the structural benefits of functionally graded concrete materials (FGCM) for rigid pavements by testing and modeling the fracture behavior of different combinations of layered plain and synthetic fiber-reinforced concrete materials. Fracture parameters and the post-peak softening behavior were obtained for each FGCM beam configuration by the three point bending beam test. The peak loads and initial fracture energy between the plain, fiber-reinforced, and FGCM signified similar crack initiation. The total fracture energy indicated improvements in fracture behavior of FGCM relative to full-depth plain concrete. The fracture behavior of FGCM depended on the position of the fiber-reinforced layer relative to the starter notch. The fracture parameters of both fiber-reinforced and plain concrete were embedded into a finite element-based cohesive zone model. The model successfully captured the experimental behavior of the FGCMs and predicted the fracture behavior of proposed FGCM configurations and structures. This integrated approach (testing and modeling) demonstrates the viability of FGCM for designing layered concrete pavements system

The Fire Resistance Performance of Recycled Aggregate Concrete Columns with Different Concrete Compressive Strengths

Science.gov (United States)

Dong, Hongying; Cao, Wanlin; Bian, Jianhui; Zhang, Jianwei

2014-01-01

In order to ascertain the fire resistance performance of recycled aggregate concrete (RAC) components with different concrete compressive strengths, four full-scaled concrete columns were designed and tested under high temperature. Two of the four specimens were constructed by normal concrete with compressive strength ratings of C20 and C30, respectively, while the others were made from recycled coarse aggregate (RCA) concrete of C30 and C40, respectively. Identical constant axial forces were applied to specimens while being subjected to simulated building fire conditions in a laboratory furnace. Several parameters from the experimental results were comparatively analyzed, including the temperature change, vertical displacement, lateral deflection, fire endurance, and failure characteristics of specimens. The temperature field of specimens was simulated with ABAQUS Software (ABAQUS Inc., Provindence, RI, USA) and the results agreed quite well with those from the experiments. Results show that the rate of heat transfer from the surface to the interior of the column increases with the increase of the concrete’s compressive strength for both RAC columns and normal concrete columns. Under the same initial axial force ratio, for columns with the same cross section, those with lower concrete compressive strengths demonstrate better fire resistance performance. The fire resistance performance of RAC columns is better than that of normal concrete columns, with the same concrete compressive strength. PMID:28788279

Metrology Needs for Predicting Concrete Pumpability

Directory of Open Access Journals (Sweden)

Myoungsung Choi

2015-01-01

Full Text Available With the increasing use of pumping to place concrete, the development and refinement of the industry practice to ensure successful concrete pumping are becoming important needs for the concrete construction industry. To date, research on concrete pumping has been largely limited to a few theses and research papers. The major obstacle to conduct research on concrete pumping is that it requires heavy equipment and large amounts of materials. Thus, developing realistic and simple measurement techniques and prediction tools is a financial and logistical challenge that is out of reach for small research labs and many private companies in the concrete construction industry. Moreover, because concrete pumping involves the flow of a complex fluid under pressure in a pipe, predicting its flow necessitates detailed knowledge of the rheological properties of concrete, which requires new measurement science. This paper summarizes the technical challenges associated with concrete pumping and the development in concrete pumping that have been published in the technical literature and identifies future research needed for the industry to develop best practices for ensuring successful concrete pumping in the field.

Shaking Table Tests of Reinforced Concrete Frames

DEFF Research Database (Denmark)

Skjærbæk, P. S.; Kirkegaard, Poul Henning; Nielsen, Søren R.K.

-varying systems and to verify various methods for damage assessment of reinforced concrete structures from soft motion measurements. In this study the maximum softening concept will be evaluated. In the paper the assessment obtained by this method is compared to visual damage assessment. The structures considered...... vector ARMA model is suitable for modal identification of degrading reinforced concrete structures and the maximum softening damage index calculated from the obtained identification provides a valuable tool for assessment of the damage state of the structure....

SHAPE CHARACTERIZATION OF CONCRETE AGGREGATE

Directory of Open Access Journals (Sweden)

Jing Hu

2011-05-01

Full Text Available As a composite material, the performance of concrete materials can be expected to depend on the properties of the interfaces between its two major components, aggregate and cement paste. The microstructure at the interfacial transition zone (ITZ is assumed to be different from the bulk material. In general, properties of conventional concrete have been found favoured by optimum packing density of the aggregate. Particle size is a common denominator in such studies. Size segregation in the ITZ among the binder particles in the fresh state, observed in simulation studies by concurrent algorithm-based SPACE system, additionally governs density as well as physical bonding capacity inside these shell-like zones around aggregate particles. These characteristics have been demonstrated qualitatively pertaining also after maturation of the concrete. Such properties of the ITZs have direct impact on composite properties. Despite experimental approaches revealed effects of aggregate grain shape on different features of material structure (among which density, and as a consequence on mechanical properties, it is still an underrated factor in laboratory studies, probably due to the general feeling that a suitable methodology for shape characterization is not available. A scientific argument hindering progress is the interconnected nature of size and shape. Presently, a practical problem preventing shape effects to be emphasized is the limitation of most computer simulation systems in concrete technology to spherical particles. New developments at Delft University of Technology will make it possible in the near future to generate jammed states, or other high-density fresh particle mixtures of non-spherical particles, which thereupon can be subjected to hydration algorithms. This paper will sketch the outlines of a methodological approach for shape assessment of loose (non-embedded aggregate grains, and demonstrate its use for two types of aggregate, allowing

Integrated Monitoring System for Durability Assessment of Concrete Bridges

Directory of Open Access Journals (Sweden)

Cristian-Claudiu Comisu

2005-01-01

Full Text Available An ageing and deteriorating bridge stock presents the bridge owners with the growing challenge of maintaining the structures at a satisfactory level of safety, performance and aesthetic appearance within the allocated budgets. This task calls for optimized bridge management based on efficient methods of selecting technical and economical optimal maintenance and rehabilitation strategies. One of the crucial points in the assessment of the current condition and future development and performance. Selecting the optimal maintenance and rehabilitation strategy within the actual budget is a key point in bridge management for which an accurate assessment of performance and deterioration rate is necessary. For this assessment, the use of integrated monitoring system has several advantages compared to the traditional approach of scattered visual inspections combined with occasional on site testing with portable equipment and laboratory testing of collected samples. For this reason, attention is more focusing on the development of permanent integrated monitoring system for durability assessment of concrete bridges. It is estimated that with the implementation of such integrated monitoring systems, it should be possible to reduce the operating costs of inspections and maintenance by 25% and the operator of the structures will be able to take protective actions before damaging processes start. This paper indentifies the main bridge owner requirements to integrated monitoring systems and outlines how monitoring systems may be used for performance and deterioration rate assessment to establish a better basis for selecting the optimal maintenance and rehabilitation strategy.

Damage induced by continued corrosion in concrete repair systems

NARCIS (Netherlands)

Luckovic, M.; Savija, B.; Schlangen, E.

2014-01-01

Corrosion of steel reinforcement is the main cause of deterioration in reinforced concrete structures. After the repair, corrosion of the steel might continue and even accelerate. While the development of the corrosion cell depends on many parameters and is difficult to control, the occurrence of

Experimental study of sodium fires on concrete based on the sodium-concrete reaction and its consequences: study of the behavior of various concretes under metallic sheaths

International Nuclear Information System (INIS)

Berlin; Colome, J.; Malet, J.C.

The problem created by the violent reaction between hot sodium and concrete has only recently been recognized. Its importance was evidenced during experiments in which the sodium-barium oxide concrete reactions led to violent explosions. SESR approached this question during its experimental programs Cassandre and Lucifer. The Cassandre 01 experiment demonstrated the sodium-ordinary concrete reaction, where sodium was burned directly in a concrete vat. The consequences of this fire, pulverization of sodium particles, explosions and deterioration of the concrete led to consideration of protecting the concrete. Among possible shieldings sheath metal appeared to be the safest solution. The Cassandre 08, Lucifer 01 and Lucifer 04 experiments were used to study the behavior of various qualities of concrete protected from fire by a metal wall. The results show that a metal cladding efficiently protects concrete from sodium leaks

Experimental investigation of photocatalytic effects of concrete in air purification adopting entire concrete waste reuse model.

Science.gov (United States)

Xu, Yidong; Chen, Wei; Jin, Ruoyu; Shen, Jiansheng; Smallbone, Kirsty; Yan, Chunyang; Hu, Lei

2018-07-05

This research investigated the capacities of recycled aggregate concrete adopting entire concrete waste reuse model in degrading NO 2. Two major issues within environmental sustainability were addressed: concrete waste reuse rate and mitigation of hazards substances in the polluted air. The study consisted of two stages: identification of proper replacement rates of recycled concrete wastes in new concrete mixture design, and the evaluation of photocatalytic performance of recycled aggregate concrete in degrading NO 2 . It was found that replacement rates up to 3%, 30%, and 50% for recycled power, recycled fine aggregate, and recycled coarse aggregate respectively could be applied in concrete mixture design without deteriorating concrete strength. Recycled aggregates contained both positive attributes ("internal curing") and negative effects (e.g., lower hardness) to concrete properties. It was found that 30%-50% of natural coarse aggregate replaced by recycled coarse aggregates coated with TiO 2 would significantly improve the photocatalytic performance of concrete measured by degradation rate of NO 2 . Micro-structures of recycled aggregates observed under microscope indicated that soaking recycled aggregates in TiO 2 solution resulted in whiskers that filled the porosity within recycled aggregates which enhanced concrete strength. Copyright © 2018 Elsevier B.V. All rights reserved.

Mechanical Properties of Steel Fiber Reinforced all Lightweight Aggregate Concrete

Science.gov (United States)

Yang, Y. M.; Li, J. Y.; Zhen, Y.; Nie, Y. N.; Dong, W. L.

2018-05-01

In order to study the basic mechanical properties and failure characteristics of all lightweight aggregate concrete with different volume of steel fiber (0%, 1%, 2%), shale ceramsite is used as light coarse aggregate. The shale sand is made of light fine aggregate and mixed with different volume of steel fiber, and the mix proportion design of all lightweight aggregate concrete is carried out. The cubic compressive strength, axial compressive strength, flexural strength, splitting strength and modulus of elasticity of steel fiber all lightweight aggregate concrete were studied. Test results show that the incorporation of steel fiber can restrict the cracking of concrete, improve crack resistance; at the same time, it shows good plastic deformation ability and failure morphology. It lays a theoretical foundation for further research on the application of all lightweight aggregate concrete in structural systems.

Acid Mine Drainage Research in Gauteng Highlighting Impacts on Infrastructure and Innovation of Concrete-Based Remedial Systems

Science.gov (United States)

Diop, S.; Ekolu, S.; Azene, F.

2013-12-01

Acid mine drainage (AMD) is presently one of the most important environmental problems in in the densely populated Gauteng Province, South Africa. The threat of acid mine drainage has demanded short-term interventions (some of which are being implemented by government) but more importantly sustainable long-term innovative solutions. There have been moments of public apprehension with some media reports dubbing the current scenario as a future 'nightmare of biblical proportions' and 'South Africa's own Chernobyl' that could cause dissolving of concrete foundations of buildings and reinforcement steel, leading to collapse of structures. In response to the needs of local and provincial authorities, this research was conducted to (1) generate scientific understanding of the effects of AMD on infrastructure materials and structures, and (2) propose innovative long-term remedial systems based on cementitious materials for potential AMD treatment applications of engineering scale. Two AMD solutions from the goldfields and two others from the coalfields were used to conduct corrosion immersion tests on mild steel, stainless steel, mortars, pastes and concretes. Results show that AMD water from the gold mines is more corrosive than that from the coal mines, the corrosion rate of the former being about twice that of the latter. The functionality of metal components of mild steel can be expected to fail within one month of exposure to the mine water. The investigation has also led to development of a pervious concrete filter system of water-cement ratio = 0.27 and cement content = 360 kg/m3, to be used as a permeable reactive barrier for AMD treatment. Early results show that the system was effective in removing heavy metal contaminants with removal levels of 30% SO4, 99% Fe, 50-83% Mn, 85% Ca, and 30% TDS. Further work is on-going to improve and optimise the system prior to field demonstration studies.

Electrokenitic Corrosion Treatment of Concrete

Science.gov (United States)

Cardenas, Henry E (Inventor)

2015-01-01

A method and apparatus for strengthening cementitious concrete by placing a nanoparticle carrier liquid in contact with a first surface of a concrete section and inducing a current across the concrete section at sufficient magnitude and for sufficient time that nanoparticles in the nanoparticle carrier liquid migrate through a significant depth of the concrete section.

Electrokinetic Strength Enhancement of Concrete

Science.gov (United States)

Cardenas, Henry E. (Inventor)

2016-01-01

A method and apparatus for strengthening cementitious concrete by placing a nanoparticle carrier liquid in contact with a first surface of a concrete section and inducing a current across the concrete section at sufficient magnitude and for sufficient time that nanoparticles in the nanoparticle carrier liquid migrate through a significant depth of the concrete section.

Assessment of mass fraction and melting temperature for the application of limestone concrete and siliceous concrete to nuclear reactor basemat considering molten core-concrete interaction

Energy Technology Data Exchange (ETDEWEB)

Lee, Ho Jae; Kim, Do Gyeum [Korea Institute of Civil Engineering and Building Technology, Goyang (Korea, Republic of); Cho, Jae Leon [Korea Hydro and Nuclear Power Co., Ulsan (Korea, Republic of); Yoon, Eui Sik [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of); Cho, Myung Suk [Korea Hydro and Nuclear Power Co., Central Research Institute, Daejeon (Korea, Republic of)

2016-04-15

Severe accident scenarios in nuclear reactors, such as nuclear meltdown, reveal that an extremely hot molten core may fall into the nuclear reactor cavity and seriously affect the safety of the nuclear containment vessel due to the chain reaction caused by the reaction between the molten core and concrete. This paper reports on research focused on the type and amount of vapor produced during the reaction between a high-temperature molten core and concrete, as well as on the erosion rate of concrete and the heat transfer characteristics at its vicinity. This study identifies the mass fraction and melting temperature as the most influential properties of concrete necessary for a safety analysis conducted in relation to the thermal interaction between the molten core and the basemat concrete. The types of concrete that are actually used in nuclear reactor cavities were investigated. The H2O content in concrete required for the computation of the relative amount of gases generated by the chemical reaction of the vapor, the quantity of CO2 necessary for computing the cooling speed of the molten core, and the melting temperature of concrete are evaluated experimentally for the molten core-concrete interaction analysis.

Probabilistic design of fibre concrete structures

Science.gov (United States)

Pukl, R.; Novák, D.; Sajdlová, T.; Lehký, D.; Červenka, J.; Červenka, V.

2017-09-01

Advanced computer simulation is recently well-established methodology for evaluation of resistance of concrete engineering structures. The nonlinear finite element analysis enables to realistically predict structural damage, peak load, failure, post-peak response, development of cracks in concrete, yielding of reinforcement, concrete crushing or shear failure. The nonlinear material models can cover various types of concrete and reinforced concrete: ordinary concrete, plain or reinforced, without or with prestressing, fibre concrete, (ultra) high performance concrete, lightweight concrete, etc. Advanced material models taking into account fibre concrete properties such as shape of tensile softening branch, high toughness and ductility are described in the paper. Since the variability of the fibre concrete material properties is rather high, the probabilistic analysis seems to be the most appropriate format for structural design and evaluation of structural performance, reliability and safety. The presented combination of the nonlinear analysis with advanced probabilistic methods allows evaluation of structural safety characterized by failure probability or by reliability index respectively. Authors offer a methodology and computer tools for realistic safety assessment of concrete structures; the utilized approach is based on randomization of the nonlinear finite element analysis of the structural model. Uncertainty of the material properties or their randomness obtained from material tests are accounted in the random distribution. Furthermore, degradation of the reinforced concrete materials such as carbonation of concrete, corrosion of reinforcement, etc. can be accounted in order to analyze life-cycle structural performance and to enable prediction of the structural reliability and safety in time development. The results can serve as a rational basis for design of fibre concrete engineering structures based on advanced nonlinear computer analysis. The presented

Fiber-reinforced concretes with a high fiber volume fraction — a look in future. Can a design determine the fiber amount in concrete in real time in every part of a structure in production?

Science.gov (United States)

Tepfers, R.

2010-09-01

In near future, when the control of the load-bearing capacity of fiber-only-reinforced concrete members will be safely guaranteed, the deletion of the ordinary continuous steel reinforcing bars might be possible. For the time being, it is difficult to change the fiber amount during the casting with today's techniques. Therefore, the fiber concentration has to be determined by the maximum tensile stress in concrete structural members, resulting in an unnecessary fiber addition in compressed zones. However, if the right amount of fibers could be regulated and added to concrete in real time at the pump outlet, a future vision could be to design and produce a structure by using FEM-controlled equipment. The signals from calculation results could be transmitted to a concrete casting system for addition of a necessary amount of fibers to take care of the actual tensile stresses in the right position in the structure. The casting location could be determined by using a GPS for positioning the pump outlet for targeting the casting location horizontally and a laser vertically. The addition of fibers to concrete at the outlet of a concrete pump and proportioning them there according to the actual needs of the stress situation in a structure, given by a FEM analysis in real time, is a future challenge. The FEM analysis has to be based on material properties of fiber-only-reinforced concrete. This means that the resistance and stiffness of different-strength concrete members with a varying fiber content has to be determined in tests and conveyed to the FEM analysis. The FEM analysis has to be completed before the casting and controlled. Then it can be used as the base for adding a correct amount of fibers to concrete in every part of the structure. Thus, a system for introducing a correct amount of fibers into concrete has to be developed. The fibers have to be added at the outlet of concrete pump. Maybe a system to shotcrete concrete with electronically controlled fiber

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

International Nuclear Information System (INIS)

Casson, R.B.J.; Davies, I.L.

1986-01-01

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

Comparison on Heat of Hydration between Current Concrete for NPP and High Fluidity Concrete including Pozzolan Powders

International Nuclear Information System (INIS)

Noh, Jea Myoung; Cho, Myung Sug

2010-01-01

Nuclear power plant (NPP) concrete structures are exposed to many construction factors that lower the quality of concrete due to densely packed reinforcements and heat of hydration since they are mostly constructed with mass concrete. The concrete currently being used in Korean NPPs is mixed with Type I cement and fly ash. However, there is a demand to improve the performance of concrete with reduced heat of hydration and superior constructability. Many advantages such as improving workability and durability of concrete and decreasing heat of hydration are introduced by replacing cement with pozzolan binders. Therefore, the manufacturing possibility of high fluidity concrete should be investigated through applying multi-component powders blended with pozzolan binders to the concrete structure of NPPs, while the researches on properties, characteristic of hydration, durability and long-term behavior of high fluidity concrete using multi-component cement should be carried out. High fluidity concrete which is made using portland cement and pozzlonan powders such as fly ash and blast furnace slag has better properties on heat of hydration than the concrete currently in use for NPPs

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.

Service life and life cycle cost modelling of cathodic protection systems for concrete structures

NARCIS (Netherlands)

Polder, R.B.; Leegwater, G.; Worm, D.; Courage, W.

2012-01-01

Corrosion of reinforcing steel in concrete structures causes concrete cracking, steel diameter reduction and eventually loss of safety. In infrastructure this is mainly due to penetration of chloride ions from de-icing or marine salts. Conventional repair means heavy, labour intensive and costly

Mixed materials for concrete. Concrete yo konwazai ni tsuite

Energy Technology Data Exchange (ETDEWEB)

Kono, K [Tokushima Univ., Tokushima (Japan). Faculty of Engineering

1994-07-05

The materials except cement, water and aggregate added into the cement paste, mortar or concrete before the execution of smashing are called mixed materials. The mixed materials are indispensable to the concrete for improving the quality of the fresh concrete as well as the hardened concrete; providing the characteristics suitable for the operation; and increasing the economy. In this paper, the main mixed materials including fly ash, which is the by-product in coal thermoelectric power station; silica fume; micropowder of slag in blast furnace; expansive materials and so on are described summarily. Especially, silica fume is the by-product, which are the super micro-powders with the average size around 0.1 micrometer, collected by the dust-collector from the waste gas generated during the manufacture in the electric furnace of ferrosilicon, which is an alloy iron, or silicon metal used as the deacidificating and desulfurizing agents in the steel production. But the most part thereof is depended on the import since the domestic output is low. 38 refs., 19 figs., 6 tabs.

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...... 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 higher the volume of gel solid relative to the space available for it, the lower the chloride migration coefficient, because the pore system becomes more tortuous and the porosity becomes less....

Optimum concrete compression strength using bio-enzyme

OpenAIRE

Bagio Tony Hartono; Basoeki Makno; Tistogondo Julistyana; Pradana Sofyan Ali

2017-01-01

To make concrete with high compressive strength and has a certain concrete specifications other than the main concrete materials are also needed concrete mix quality control and other added material is also in line with the current technology of concrete mix that produces concrete with specific characteristics. Addition of bio enzyme on five concrete mixture that will be compared with normal concrete in order to know the optimum level bio-enzyme in concrete to increase the strength of the con...

Structural performance of new thin-walled concrete sandwich panel system reinforced with bfrp shear connectors

DEFF Research Database (Denmark)

Hodicky, Kamil; Hulin, Thomas; Schmidt, Jacob Wittrup

2013-01-01

This paper presents a new thin-walled concrete sandwich panel system reinforced with basalt fiber-reinforced plastic (BFRP) with optimum structural performances and a high thermal resistance developed by Connovate and Technical University of Denmark. The shear connecting system made of a BFRP grid...... is described and provides information on the structural design with its advantages. Experimental and numerical investigations of the BFRP connecting systems were performed. The experimental program included testing of small scale specimens by applying shear (push-off) loading and semi-full scale specimens...... on finite element modelling showed that the developed panel system meets the objectives of the research and is expected to have promising future....

Early Property Development in Concrete

DEFF Research Database (Denmark)

Normann, Gitte; Munch-Petersen, Christian

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

Estimating Durability of Reinforced Concrete

Science.gov (United States)

Varlamov, A. A.; Shapovalov, E. L.; Gavrilov, V. B.

2017-11-01

In this article we propose to use the methods of fracture mechanics to evaluate concrete durability. To evaluate concrete crack resistance characteristics of concrete directly in the structure in order to implement the methods of fracture mechanics, we have developed special methods. Various experimental studies have been carried out to determine the crack resistance characteristics and the concrete modulus of elasticity during its operating. A comparison was carried out for the results obtained with the use of the proposed methods and those obtained with the standard methods for determining the concrete crack resistance characteristics.

Low-pH concrete plug for sealing the KBS-3V deposition tunnels

International Nuclear Information System (INIS)

Malm, Richard

2012-01-01

In SKB's main alternative for final repository of radioactive material, KBS-3V, the backfilled deposition tunnels will be separated from the remaining tunnel system with concrete plugs. These concrete plugs will be designed for a life span of 100 years and their function shall maintain until the transport tunnels outside the plug are backfilled and the natural geohydrological conditions have been restored. The purpose of this report is to document the results and the evaluation from this project and motivate the choice of the most appropriate design for closing the deposition tunnels in the spent fuel repository. The purpose has also been to investigate and present the loads acting on the plug system and determine the load capacity of the concrete plug. This report is the result of a project conducted between 2009-01-01 - 2010-12-31 and the project group has made its assessment based on the conditions and requirements that are present today. The entire design of the plug system is part of this project, where the plug system consists of a filter, a bentonite seal and a cast-in-place concrete plug. Two different conceptual design alternatives for the concrete plug have been studied in this report, one long tapered plug and one dome shaped plug. The results in this report focus on the choice of the conceptual design for the concrete plug and its possibility to assist the entire plug system to satisfy its requirements. It is a complicated task to dispose the radioactive waste and it sets high technical requirements on the design and the production of the backfill and the closing of the deposition tunnels. The aim of this project is to design and develop a plug system suitable for production. This is done by the means of numerical calculations and analyses. The primary function of the concrete plug is to act as a resistance to the external loads originated from the axial expansion of the backfill and the water pressure. However, the entire plug system has a requirement

Low-pH concrete plug for sealing the KBS-3V deposition tunnels

Energy Technology Data Exchange (ETDEWEB)

Malm, Richard (Vattenfall Power Consultant AB (Sweden))

2012-01-15

In SKB's main alternative for final repository of radioactive material, KBS-3V, the backfilled deposition tunnels will be separated from the remaining tunnel system with concrete plugs. These concrete plugs will be designed for a life span of 100 years and their function shall maintain until the transport tunnels outside the plug are backfilled and the natural geohydrological conditions have been restored. The purpose of this report is to document the results and the evaluation from this project and motivate the choice of the most appropriate design for closing the deposition tunnels in the spent fuel repository. The purpose has also been to investigate and present the loads acting on the plug system and determine the load capacity of the concrete plug. This report is the result of a project conducted between 2009-01-01 - 2010-12-31 and the project group has made its assessment based on the conditions and requirements that are present today. The entire design of the plug system is part of this project, where the plug system consists of a filter, a bentonite seal and a cast-in-place concrete plug. Two different conceptual design alternatives for the concrete plug have been studied in this report, one long tapered plug and one dome shaped plug. The results in this report focus on the choice of the conceptual design for the concrete plug and its possibility to assist the entire plug system to satisfy its requirements. It is a complicated task to dispose the radioactive waste and it sets high technical requirements on the design and the production of the backfill and the closing of the deposition tunnels. The aim of this project is to design and develop a plug system suitable for production. This is done by the means of numerical calculations and analyses. The primary function of the concrete plug is to act as a resistance to the external loads originated from the axial expansion of the backfill and the water pressure. However, the entire plug system has a

Radiometric assessment of quality of concrete mix with respect to hardened concrete strength

International Nuclear Information System (INIS)

Czechowski, J.

1983-01-01

The experiments have confirmed the relationship between the intensity of backscattered gamma radiation and the density of fresh concrete, and also between the flow of backscattered fast neutrons and the water content. From the said two parameters it is possible to derive the compression strength of concrete over the determined period of mix hardening, e.g., after 28 days. For a certain composition of concrete it is possible to derive empirical relations between the intensity of backscattered gamma radiation and neutrons and concrete strength after hardening and to construct suitable nomograms. (Ha)

Durability assessment of recycled concrete aggregates for use in new concrete.

Science.gov (United States)

2012-06-01

The primary goal of this research project was to investigate the long-term durability of concrete incorporating : recycled concrete aggregate (RCA) through accelerated laboratory testing. Overall it was found that modifications to : standard aggregat...

Shrinkage Reducing Admixture for Concrete

OpenAIRE

ECT Team, Purdue

2007-01-01

Concrete shrinkage cracking is a common problem in all types of concrete structures, especially for structures and environments where the cracks are prevalent and the repercussions are most severe. A liquid shrinkage reducing admixture for concrete, developed by GRACE Construction Products and ARCO Chemical Company, that reduces significantly the shrinkage during concrete drying and potentially reduces overall cracking over time.

CONCRETE PROPERTIES IMPROVEMENT OF SLAB TRACKS USING CHEMICAL ADDITIVES

Directory of Open Access Journals (Sweden)

V. V. Pristinskaya

2015-11-01

Full Text Available Purpose. On the Railways of Ukraine a very large number of slab tracks are operated with cracks. Many scientific works of previous years are dedicated to improving the design of slab tracks. The main causes of defects are: poor exploitation of the track; insufficient physic-mechanical characteristics of concrete; poor quality of initial materials. It is therefore necessary to develop an optimum concrete mix for the manufacture of these concrete products. Methodology. To assess the impact of individual factors and effects of their interactions on properties of concrete mix and concrete method of experimental and statistical modeling was used. At this, methodological fundamentals of mathematical experiment planning in concrete technology and modern methods of optimization of composite materials were taking into account. Based on the obtained data during the planned experiment conducting, including15 studies and using the computer program MathCad, were obtained the regression equations, which describe the relevant physical and mechanical properties of concrete. On the basis of the equations with the help of computer program MATLAB R2012b the graphs were drawn, illustrating the dependences of system response from the changes of two factors at a fixed value of the third factor. Findings. Firstly was the analysis of cracks that occur in the process of operation in the constructions of slab tracks. Further reasons of possible occurrence of these cracks were presented. In the process of the conducted research the author has concluded that for rational concrete mix development it is necessary to conduct the planned experiment with the use of quality materials. It was established that to increase the strength, chemical additives should be added in to concrete mix, it will let reduce cement amount. Originality. Experiments proved the usage of modern chemical additives in order to improve the properties of concrete. Models were developed, reflecting

Evolution of sorption properties in large-scale concrete structures accounting for long-term physical-chemical concrete degradation - 59297

International Nuclear Information System (INIS)

Perko, Janez; Jacques, Diederik; Mallants, Dirk; Seetharam, Suresh

2012-01-01

Long-term safety of radioactive waste disposal facilities relies on the longevity of natural or engineered barriers designed to minimize the migration of contaminants from the facility into the environment. Especially near surface disposal facilities, such as planned by ONDRAF/NIRAS for the Dessel site in Belgium, long-term safety relies almost exclusively on the containment ability of the engineered barriers (EB) with concrete being the most important EB material used. Concrete is preferred over other materials mainly due to its favourable chemical properties resulting in a high chemical retention capacity, and owing to its good hydraulic isolation properties. However, due to the long time frames typically involved in safety assessment, the chemical, physical and mechanical properties of concrete evolve in time. The alterations in concrete mineralogy also cause changes in pH and sorption behaviour for many radionuclides during chemical degradation processes. Application of dynamic sorption of concrete requires an adequate knowledge of long-term concrete degradation processes, knowledge of the effect of changing mineralogy to sorption of radionuclides and knowledge of large-scale system behaviour over time. Moreover, when applied to safety assessment models, special attention is required to assure robustness and transparency of the implementation. The discussion in this paper focuses on the sorption properties of concrete; selection of data, rescaling issues and on the hypotheses used to build a robust and yet transparent dynamic model for large-scale concrete structures for assessing the long-term performance. In this paper we summarize the steps required for the appropriate use of sorption values for large-scale cementitious components accounting for long-term concrete degradation in safety assessment studies. Four steps were recognized through the safety assessment in the framework of the license application for the near-surface disposal facility in Dessel

Intermediate-scale sodium-concrete reaction tests with basalt and limestone concrete

International Nuclear Information System (INIS)

Hassberger, J.A.; Muhlestein, L.D.

1981-01-01

Ten tests were performed to investigate the chemical reactions and rate and extent of attack between sodium and basalt and limestone concretes. Test temperatures ranged from 510 to 870 0 C (950 to 1600 0 F) and test times from 2 to 24 hours. Sodium hydroxide was added to some of the tests to assess the impact of a sodium hydroxide-aided reaction on the overall penetration characteristics. Data suggest that the sodium penetration of concrete surfaces is limited. Penetration of basalt concrete in the presence of sodium hydroxide is shown to be less severe than attack by the metallic sodium alone. Presence of sodium hydroxide changes the characteristics of sodium penetration of limestone concrete, but no major differences in bulk penetration were observed as compared to penetration by metallic sodium

Comparison of the performance of concrete-filled steel tubular and hollow steel diagrid buildings

Science.gov (United States)

Peter, Minu Ann; S, Sajith A.; Nagarajan, Praveen

2018-03-01

In the recent construction scenario, diagrid structures are becoming a popular high-rise building structural system. Diagrid structures consist of diagonals in the perimeter and an interior core. The corner and interior vertical columns are not required due to the structural efficiency of diagrid structural systems. Steel and concrete are commonly used material for diagrid. An alternate material for diagrid is concrete-filled steel tube (CFST). CFST incorporates the advantages of both steel and concrete. In CFST, the inward buckling of the steel tube is effectively prevented by the filled concrete. The compressive strength of concrete increases due to the tri-axial state of stress in concrete induced by the steel tube. The longitudinal as well as lateral reinforcement to the concrete core is also provided by the steel tube. This paper compares the performance of CFST and steel diagrid buildings using linear static analysis. For this purpose, a 12 storey and 36 storey building are analysed using finite element method and CFST diagrid building is found to perform better.

Effects of grouting, shotcreting and concrete leachates on backfill geochemistry

Energy Technology Data Exchange (ETDEWEB)

Luna, Miguel; Arcos, David; Duro, Lara [Enviros Consulting, Valldoreix, Barc elona (Spain)

2007-11-15

The use of concrete to seal open fractures (grouting) and to impermeabilise the deposition tunnels (shotcreting) has been envisaged in the construction of a high level nuclear waste (HLNW) repository according to SKB designs. Nevertheless, the geochemical effect of using concrete in the repository is not fully understood. Concrete degradation due to the interaction with groundwater can affect the performance of other repository barriers, such as the backfill material used for sealing the deposition tunnels. One of the main effects of concrete degradation is the generation of alkaline plumes. For this reason, SKB is currently planning to use a type of concrete whose degradation result in lower pH values than those developed with Ordinary Portland Cement (OPC). In order to assess the long-term geochemical effect of including low-pH concrete elements in a HLNW repository, we performed a 2D reactive-transport model of a backfilled deposition tunnel that intersects a hydraulic conductive fracture which has been partially grouted. An additional case has been modelled where part of the deposition tunnel walls were covered with a shotcrete layer. The modelling results predict the development of a high-alkalinity plume, larger in the case of considering a grouted fracture, accompanied by the precipitation of CSH-phases in the fracture. However, the effect on the backfill material is only significant if concrete is in contact with the backfill (shotcrete case). In order to conduct these models, and considering that at the beginning of the present work there was not a specific composition for such a low-pH concrete, its composition has been assumed in order to meet the expected geochemical evolution of concrete degradation according to SKB expectations. This is a pH of pore water of around 11 and the degradation of CSH phases resulting in a source for Ca and Si into the system. For this reason, jennite and tobermorite have been selected, although it is known that jennite is

Effects of grouting, shotcreting and concrete leachates on backfill geochemistry

International Nuclear Information System (INIS)

Luna, Miguel; Arcos, David; Duro, Lara

2007-11-01

The use of concrete to seal open fractures (grouting) and to impermeabilise the deposition tunnels (shotcreting) has been envisaged in the construction of a high level nuclear waste (HLNW) repository according to SKB designs. Nevertheless, the geochemical effect of using concrete in the repository is not fully understood. Concrete degradation due to the interaction with groundwater can affect the performance of other repository barriers, such as the backfill material used for sealing the deposition tunnels. One of the main effects of concrete degradation is the generation of alkaline plumes. For this reason, SKB is currently planning to use a type of concrete whose degradation result in lower pH values than those developed with Ordinary Portland Cement (OPC). In order to assess the long-term geochemical effect of including low-pH concrete elements in a HLNW repository, we performed a 2D reactive-transport model of a backfilled deposition tunnel that intersects a hydraulic conductive fracture which has been partially grouted. An additional case has been modelled where part of the deposition tunnel walls were covered with a shotcrete layer. The modelling results predict the development of a high-alkalinity plume, larger in the case of considering a grouted fracture, accompanied by the precipitation of CSH-phases in the fracture. However, the effect on the backfill material is only significant if concrete is in contact with the backfill (shotcrete case). In order to conduct these models, and considering that at the beginning of the present work there was not a specific composition for such a low-pH concrete, its composition has been assumed in order to meet the expected geochemical evolution of concrete degradation according to SKB expectations. This is a pH of pore water of around 11 and the degradation of CSH phases resulting in a source for Ca and Si into the system. For this reason, jennite and tobermorite have been selected, although it is known that jennite is

Behaviour of fibre reinforced polymer confined reinforced concrete columns under fire condition

Science.gov (United States)

Chowdhury, Ershad Ullah

In recent years, fibre reinforced polymer (FRP) materials have demonstrated enormous potential as materials for repairing and retrofitting concrete bridges that have deteriorated from factors such as electro-chemical corrosion and increased load requirements. However, concerns associated with fire remain an obstacle to applications of FRP materials in buildings and parking garages due to FRP's sensitivity to high temperatures as compared with other structural materials and to limited knowledge on their thermal and mechanical behaviour in fire. This thesis presents results from an ongoing study on the fire performance of FRP materials, fire insulation materials and systems, and FRP wrapped reinforced concrete columns. The overall goal of the study is to understand the fire behaviour of FRP materials and FRP strengthened concrete columns and ultimately, provide rational fire safety design recommendations and guidelines for FRP strengthened concrete columns. A combined experimental and numerical investigation was conducted to achieve the goals of this research study. The experimental work consisted of both small-scale FRP material testing at elevated temperatures and full-scale fire tests on FRP strengthened columns. A numerical model was developed to simulate the behaviour of unwrapped reinforced concrete and FRP strengthened reinforced concrete square or rectangular columns in fire. After validating the numerical model against test data available in literature, it was determined that the numerical model can be used to analyze the behaviour of concrete axial compressive members in fire. Results from this study also demonstrated that although FRP materials experience considerable loss of their mechanical and bond properties at temperatures somewhat below the glass transition temperature of the resin matrix, externally-bonded FRP can be used in strengthening concrete structural members in buildings, if appropriate supplemental fire protection system is provided over

Assessment of Mass Fraction and Melting Temperature for the Application of Limestone Concrete and Siliceous Concrete to Nuclear Reactor Basemat Considering Molten Core–Concrete Interaction

Directory of Open Access Journals (Sweden)

Hojae Lee

2016-04-01

Full Text Available Severe accident scenarios in nuclear reactors, such as nuclear meltdown, reveal that an extremely hot molten core may fall into the nuclear reactor cavity and seriously affect the safety of the nuclear containment vessel due to the chain reaction caused by the reaction between the molten core and concrete. This paper reports on research focused on the type and amount of vapor produced during the reaction between a high-temperature molten core and concrete, as well as on the erosion rate of concrete and the heat transfer characteristics at its vicinity. This study identifies the mass fraction and melting temperature as the most influential properties of concrete necessary for a safety analysis conducted in relation to the thermal interaction between the molten core and the basemat concrete. The types of concrete that are actually used in nuclear reactor cavities were investigated. The H2O content in concrete required for the computation of the relative amount of gases generated by the chemical reaction of the vapor, the quantity of CO2 necessary for computing the cooling speed of the molten core, and the melting temperature of concrete are evaluated experimentally for the molten core–concrete interaction analysis.

Enhancing corrosion resistance of reinforced concrete structures with hybrid fiber reinforced concrete

International Nuclear Information System (INIS)

Blunt, J.; Jen, G.; Ostertag, C.P.

2015-01-01

Highlights: • Reinforced concrete beams were subjected to cyclic flexural loading. • Hybrid fiber reinforced composites were effective in reducing corrosion rates. • Crack resistance due to fibers increased corrosion resistance of steel rebar. • Galvanic corrosion measurements underestimated corrosion rates. • Polarization resistance measurements predicted mass loss more accurately. - Abstract: Service loads well below the yield strength of steel reinforcing bars lead to cracking of reinforced concrete. This paper investigates whether the crack resistance of Hybrid Fiber Reinforced Concrete (HyFRC) reduces the corrosion rate of steel reinforcing bars in concrete after cyclic flexural loading. The reinforcing bars were extracted to examine their surface for corrosion and compare microcell and macrocell corrosion mass loss estimates against direct gravimetric measurements. A delay in corrosion initiation and lower active corrosion rates were observed in the HyFRC beam specimens when compared to reinforced specimens containing plain concrete matrices cycled at the same flexural load

Seismic Performance and Modeling of Reinforced Concrete and Post-Tensioned Precast Concrete Shear Walls

OpenAIRE

Tanyeri, Ahmet Can

2014-01-01

Past earthquakes have shown examples of unsatisfactory performance of buildings using reinforced concrete structural walls as the primary lateral-force-resisting system. In the 1994 Northridge earthquake, examples can be found where walls possessed too much overstrength, leading to unintended failure of collectors and floor systems, including precast and post-tensioned construction. In the 2010 Maule Chile earthquake, many structural wall buildings sustained severe damage. Although Chilean de...

Concrete thermal energy storage for steam generation

DEFF Research Database (Denmark)

Singh, Shobhana; Sørensen, Kim

2017-01-01

Establishing enhancement methods to develop cost-effective thermal energy storage technology requires a detailed analysis. In this paper, a numerical investigation of the concrete based thermal energy storage system is carried out. The storage system consists of a heat transfer fluid flowing inside...

Optimization of concrete composition in radioactive waste management

International Nuclear Information System (INIS)

Plecas, I.; Peric, A.

1995-01-01

Low and intermediate level waste represents 95% of the total wastes that is conditioned into special concrete containers. Since these containers are to protect radioactive waste safely for about 300 years, the selection and precise control of physical and mechanical characteristics of materials is very important. After volume reduction and valuable components recovery, waste materials have to be conditioned for transport, storage and disposal. Conditioning is the waste management step in which radioactive wastes are immobilized and packed. The immobilization processes involve conversation of the wastes to solid forms that reduce the potential for migration or dispersion of radionuclides from the wastes by natural processes during storage, transport and disposal. The immobilization processes involve the use of various matrices of nonradioactive materials, such as concrete, to fix the wastes as monoliths, usually directly in the waste containers used for subsequent handling. In this paper an optimization of concrete container composition, used for storing radioactive waste from nuclear power plants, is presented. Optimization was performed on the composition of the concrete that is used in the container production. In experiments, the authors tried to obtain the best mechanical characteristics of the concrete, varying the weight percentage of the granulate due to its diameter, water-to-cement ratios and type of the cements that were used in preparing the concrete container formulation. Concrete containers, that were optimized in the manner described in this paper, will be in used for the radioactive waste materials final disposal, using the concept of the engineer trench system facilities

Development of high performance and low radio activation concrete material for concrete cask

International Nuclear Information System (INIS)

Shirai, Koji; Sonobe, Ryoji

2005-01-01

For the realization of the long-term storage of the nuclear spent fuel with the concrete cask technology, a low radio activation high performance concrete was developed, which contains extremely small quantity of Eu and Co and assures enough heat-resistance and durability for degradation. Firstly, the activation analysis was performed to estimate the allowable content limit of their quantities according to the rules issued by Japanese government for determining the classification of the radioactive waste. Secondly, various candidate materials were sampled and irradiated to find out the activation level. As a result, as the optimum concrete mix, the combination of limestone and white fused alumina aggregates with fry-ash was chosen. Moreover, the basic characteristics of the candidate concrete (workability, strength under high temperature, heat conductivity and so on) were evaluated, and the thermal cracking test was executed with hollow cylinders. Finally, the developed concrete material seems to be suitable for the long-term use of concrete cask considering the low activation, high heat resistance and durability during storage. (author)

Investigation on dynamic performance of concrete column crumb rubber steel and fiber concrete

Science.gov (United States)

Siti Nurul Nureda, M. Z.; Mariyana, A. K.; Khiyon, M. Iqbal; Rahman, M. S. Abdul; Nurizaty, Z.

2017-11-01

In general the Normal Concrete (NC) are by quasi-brittle failure, where, the nearly complete loss of loading capacity, once failure is initiated especially under dynamic loadings. The significance of this study is to improve the damping properties of concrete structure by utilization of the recycled materials from waste tires to be used in concrete as structural materials that improve seismic performance. In this study, the concrete containing 10% of fine crumb rubber and 1 % volume fraction of steel fiber from waste tires is use to investigate the dynamic performance (natural frequency and damping ratio).A small scale column were fabricated from Treated Crumb Rubber and Steel Fiber Concrete (TCRSFC) and NC were cast and cured for 28 days to investigate the dynamic performance. Based on analysis, dynamic modulus, damping ratio and natural frequency of TCRSFC has improved considerably by 5.18%, 109% and 10.94% when compared with NC. The TCRSFC producing concrete with the desired properties as well as to introduce the huge potential as dynamic resistance structure from severe damage especially prevention on catastrophic failure.

Retrieval Contexts and the Concreteness Effect: Dissociations in Memory of Concrete and Abstract Words

NARCIS (Netherlands)

ter Doest, L.; Semin, G.R.

2005-01-01

Decades of research on the concreteness effect, namely better memory for concrete as compared with abstract words, suggest it is a fairly robust phenomenon. Nevertheless, little attention has been given to limiting retrieval contexts. Two experiments evaluated intentional memory for concrete and

Copolymer natural latex in concrete: Dynamic evaluation through energy dissipation of polymer modified concrete

Science.gov (United States)

Andayani, Sih Wuri; Suratman, Rochim; Imran, Iswandi; Mardiyati

2018-05-01

Portland cement concrete have been used in construction due to its strength and ecomical value. But it has some limitations, such low flexural strength, low tensile strength, low chemical resistant and etc. Due to its limitations in flexural and tensile strength, Portland cement concrete more susceptible by seismic force. There are some methods for improving its limitations. Polymer addition into concrete mixture could be one of solution for improving the flexural and tensile strength, in aiming to get erthquake resistant properties. Also, the eartquake resistant could be achieved by improving energy dissipation capacity. In this research, the earthquake resistant evalution was approached from dynamic evaluation through energy dissipation capacity, after polymer addition as concrete additives. The polymers were natural latex (Indonesian naural resource) grafted with styrene and methacrylate, forming copolymer - natural latex methacrylate (KOLAM) and copolymer - natural latex styrene (KOLAS). They were added into concrete mixture resulting polymer modified concrete. The composition of polymer are 1%, 5% and 10% weight/weight of cement. The higher capacity of energy dissipation will give more capability in either absorbing or dissipating energy, and it was predicted would give better earthquake resistant.. The use of KOLAM gave better performance than KOLAS in energy dissipation capacity. It gave about 46% for addition of 1% w/w compared to Portland cement concrete. But for addition 5% w/w and 10% w/w, they gave about 7% and 5% higher energy dissipation capacity. The KOLAM addition into concrete mixture would reduce the maximum impact load with maximumabout 35% impact load reducing after 1% w/w addition. The higher concentration of KOLAM in concrete mixture, lower reducing of impact load, they were about 4% and 3% for KOLAM 5% and 10%. For KOLAS addition in any compositions, there were no positive trend either in energy dissipation capacity or impact load properties

Laboratory evaluation of recycled concrete as aggregate in new concrete pavements.

Science.gov (United States)

2014-09-01

The Washington State Department of Transportation (WSDOT) has initiated a research project to investigate the use of recycled concrete as : aggregates (RCA) in Portland (hydraulic) cement concrete pavements (PCCP). The planned source for the RCA in t...

The construction features of the deformation and force model of concrete and reinforced concrete resistance

Directory of Open Access Journals (Sweden)

Romashko Vasyl

2017-01-01

Full Text Available The main features of the deformation and force model of deformation of reinforced concrete elements and structures based on generalized diagrams of their state are considered in the article. Particular attention is focused on the basic methodological problems and shortcomings of modern "deformation" models. It is shown that in the most cases these problems can be solved by the generalized diagrams of reinforced concrete elements and structures real state. Thanks to these diagrams, the developed method: provides a single methodological approach to the calculation of reinforced concrete elements and structures normal sections for limit states; allows to reveal the internal static indeterminacy of heterogeneously deformable elements and structures in their ultimate limit state calculation; justifies the application of the basic and derived criteria of reinforced concrete elements and structures bearing capacity exhaustion; retains the essence of the physical processes of concrete and reinforced concrete structures deformation. The defining positions of the generalized (universal methodology for calculating reinforced concrete elements and structures are stated.

Influence of bagasse ash and recycled concrete aggregate on hardened properties of high-strength concrete

Directory of Open Access Journals (Sweden)

P. Rattanachu

2018-04-01

Full Text Available This research aimed to use of bagasse ash as a cement replacement in high-strength recycled aggregate concrete (HS-RAC. Crushed limestone was replaced with 100% recycled concrete aggregate (RCA and the ground bagasse ash (GBA was used to partially replace ordinary Portland cement (OPC at 20, 35 and 50%wt of binder to cast HS-RAC. The results indicated that the replacing of crushed limestone with RCA had a negative impact on the properties of the concrete. Increasing the amount of GBA in HS-RAC resulted in a decrease in density and an increase in the volume of permeable pore space. The concrete mixtures prepared with 20%wt GBA replacement of OPC promoted greater the compressive strength than the conventional concrete (CT concrete at 90 days or more. HS-RAC with GBA (up to 50% was more durable in terms of chloride ion penetration resistance, although it had lower compressive strength than the CT concrete.

concrete5 for developers

CERN Document Server

Uzayr, Sufyan bin

2014-01-01

Whether you have had some previous experience with concrete5 or are entirely new to it, this book will help you understand all that you need to know in order to get started with concrete5 development. A background in PHP is required; some knowledge of HTML/CSS is needed in order to fully grasp the concepts underlying concrete5 theme development.

Characterisation and management of concrete grinding residuals.

Science.gov (United States)

Kluge, Matt; Gupta, Nautasha; Watts, Ben; Chadik, Paul A; Ferraro, Christopher; Townsend, Timothy G

2018-02-01

Concrete grinding residue is the waste product resulting from the grinding, cutting, and resurfacing of concrete pavement. Potential beneficial applications for concrete grinding residue include use as a soil amendment and as a construction material, including as an additive to Portland cement concrete. Concrete grinding residue exhibits a high pH, and though not hazardous, it is sufficiently elevated that precautions need to be taken around aquatic ecosystems. Best management practices and state regulations focus on reducing the impact on such aquatic environment. Heavy metals are present in concrete grinding residue, but concentrations are of the same magnitude as typically recycled concrete residuals. The chemical composition of concrete grinding residue makes it a useful product for some soil amendment purposes at appropriate land application rates. The presence of unreacted concrete in concrete grinding residue was examined for potential use as partial replacement of cement in new concrete. Testing of Florida concrete grinding residue revealed no dramatic reactivity or improvement in mortar strength.

Optimum concrete compression strength using bio-enzyme

Directory of Open Access Journals (Sweden)

Bagio Tony Hartono

2017-01-01

Full Text Available To make concrete with high compressive strength and has a certain concrete specifications other than the main concrete materials are also needed concrete mix quality control and other added material is also in line with the current technology of concrete mix that produces concrete with specific characteristics. Addition of bio enzyme on five concrete mixture that will be compared with normal concrete in order to know the optimum level bio-enzyme in concrete to increase the strength of the concrete. Concrete with bio-enzyme 200 ml/m3, 400 ml/m3, 600 ml/m3, 800 ml/m3, 1000 ml/m3 and normal concrete. Refer to the crushing test result, its tends to the mathematical model using 4th degree polynomial regression (least quartic, as represent on the attached data series, which is for the design mix fc′ = 25 MPa generate optimum value for 33,98 MPa, on the bio-additive dosage of 509 ml bio enzymes.

Thermal treatment of recycled concrete aggegate for general use in concrete. A preliminary study

NARCIS (Netherlands)

Larbi, J.A.; Heijnen, W.M.M.; Brouwer, J.P.; Mulder, E.

2000-01-01

In this paper, the results of a preliminary laboratory study to assess the effectiveness of thermally treating recycled concrete aggregate for genera) use in concrete are presented. The samples used for the study consisted of sieved fractions of crushed concrete that were subjected to various

Utilization of recycled concrete aggregates in structural concrete by applying a fraction partitioning model

NARCIS (Netherlands)

Wouw, van de P.M.F.; Doudart de la Grée, G.C.H.; Florea, M.V.A.; Brouwers, H.J.H.; Bilek, V.; Kersner, Z.

2014-01-01

The recycling of concrete waste into new structural concrete reduces the utilization of raw materials, decreases transport and production energy cost, and saves the use of limited landfill space. Currently, recycling involves the use of recycled concrete aggregates (RCA) as road base material or in

Monolithic Concrete vs Precast Concrete for the Construction of Bridge by Th Cantilever Method

Directory of Open Access Journals (Sweden)

Morlova Dumitru Daniel

2015-07-01

Full Text Available In the article "Monolithic Concrete vs Precast Concrete for the Construction of Bridges by the Cantilever Method", there are approached a number of issues that come out in the design and execution of prestressed concrete bridge structures using the cantilever method.

Monitoring of prestressed concrete pressure vessels. II. performance of selected concrete embedment strain meters under normal and extreme environmental conditions

International Nuclear Information System (INIS)

Naus, D.J.; Hurtt, C.C.

1978-10-01

Unique types of instrumentation are used in prestressed concrete pressure vessels (PCPVs) to measure strains, stresses, deflections, prestressing forces, moisture content, temperatures, and possibly cracking. Their primary purpose is to monitor these complex structures throughout their 20- to 30-year operating lifetime in order to provide continuing assurance of their reliability and safety. Numerous concrete embedment instrumentation systems are available commercially. Since this instrumentation is important in providing continuing assurance of satisfactory performance of PCPVs, the information provided must be reliable. Therefore, laboratory studies were conducted to evaluate the reliability of these commercially available instrumentation systems. This report, the second in a series related to instrumentation embedded in concrete, presents performance-reliability data for 13 types of selected concrete embedment strain meters which were subjected to a variety of loading environments, including unloaded, thermally loaded, simulated PCPV, and extreme environments. Although only a limited number of meters of each type were tested in any one test series, the composite results of the investigation indicate that the majority of these meters would not be able to provide reliable data throughout the 20- to 30-year anticipated operating life of a PCPV. Specific conclusions drawn from the study are: (1) Improved corrosion-resistant materials and sealing techniques should be developed for meters that are to be used in PCPV environments. (2) There is a need for the development of meters that are capable of surviving in concretes where temperatures in excess of 66 0 C are present for extended periods of time. (3) Research should be conducted on other measurement techniques, such as inductance, capacitance, and fluidics

Material Evaluation of an Elastomer, Epoxy and Lightweight Concrete Rail Attachment System for Direct Fixation Light Rail Applications

Science.gov (United States)

Swarner, Benjamin R.

Sound Transit plans to extend its current light rail system, which runs along the I-5 corridor in Seattle, Washington, across the I-90 Homer Hadley floating bridge as part of a project to connect the major city centers in the region. But, no light rail has ever crossed a floating bridge due to several unique engineering challenges. One of these challenges is attaching the rails to the existing bridge deck without drilling into the bridge pontoons. This research program was developed to test and analyze a direct fixation method that uses lightweight concrete plinths and an elastomer-epoxy system to attach the rails to the bridge deck. The elastomer used was a two-part, pourable elastomer with cork particles intermixed to alter the mechanical properties of the material. A lightweight concrete mixture was analyzed for use in the plinths, and system tests investigated the system response under tensile, compressive and shear loading. The shear response of the system was examined further under varying loading conditions including different surface preparations, elastomer thicknesses, strain-rates and after freeze-thaw conditioning. Experimental data was examined for trends based on these parameters to best characterize the system, and the elastomer was evaluated in the context of modern elastomer research.

Placement of mass concrete for cast-in-place concrete piling : the effects of heat of hydration of mass concrete for cast-in-place piles.

Science.gov (United States)

2008-12-01

This report describes models, ABAQUS and Schmidt, to predict the peak temperature in the center of cast-in-place concrete piling. Five concrete piles with varying diameters and made up of concrete mixes with different percentage of fly ash are used. ...

Integration of a prototype wireless communication system with micro-electromechanical temperature and humidity sensor for concrete pavement health monitoring

Directory of Open Access Journals (Sweden)

Shuo Yang

2015-12-01

Full Text Available In recent years, structural health monitoring and management (SHMM has become a popular approach and is considered essential for achieving well-performing, long-lasting, sustainable transportation infrastructure systems. Key requirements in ideal SHMM of road infrastructure include long-term, continuous, and real-time monitoring of pavement response and performance under various pavement geometry-materials-loading configurations and environmental conditions. With advancements in wireless technologies, integration of wireless communications into sensing device is considered an alternate and superior solution to existing time- and labor-intensive wired sensing systems in meeting the requirements of an ideal SHMM. This study explored the development and integration of a wireless communications sub-system into a commercial off-the-shelf micro-electromechanical sensor-based concrete pavement monitoring system. A success-rate test was performed after the wireless transmission system was buried in the concrete slab, and the test results indicated that the system was able to provide reliable communications at a distance of more than 46 m (150 feet. This will be a useful feature for highway engineers performing routine pavement scans from the pavement shoulder without the need for traffic control or road closure.

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...

Fracture Mechanics of Concrete

DEFF Research Database (Denmark)

Ulfkjær, Jens Peder

Chapter 1 Chapter l contains the introduction to this thesis. The scope of the thesis is partly to investigate different numerical and analytical models based on fracture mechanical ideas, which are able to predict size effects, and partly to perform an experimental investigation on high-strength......Chapter 1 Chapter l contains the introduction to this thesis. The scope of the thesis is partly to investigate different numerical and analytical models based on fracture mechanical ideas, which are able to predict size effects, and partly to perform an experimental investigation on high......-strength concrete. Chapter 2 A description of the factors which influence the strength and cracking of concrete and high strength concrete is made. Then basic linear fracture mechanics is outlined followed by a description and evaluation of the models used to describe concrete fracture in tension. The chapter ends...... and the goveming equations are explicit and simple. These properties of the model make it a very powerful tool, which is applicable for the designing engineer. The method is also extended to reinforced concrete, where the results look very promising. The large experimental investigation on high-strength concrete...

Monitoring water loss form fresh concrete

DEFF Research Database (Denmark)

Jensen, Ole Mejlhede

2006-01-01

Desiccation of concrete before or during setting may lead to detrimental plastic shrinkage cracking in the concrete surface zone. Cracking due to plastic shrinkage is a major technological problem for any concrete, however, modern high-performance concretes are especially susceptible to this...... determination of the evaporation loss from hardening concrete and thus better possibility for preventing curing problems, including detrimental crack damage due to plastic shrinkage....