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Sample records for bio-shielding concrete samples

  1. Fractionation of plutonium in environmental and bio-shielding concrete samples using dynamic sequential extraction

    DEFF Research Database (Denmark)

    Qiao, Jixin; Hou, Xiaolin

    2010-01-01

    Fractionation of plutonium isotopes (238Pu, 239,240Pu) in environmental samples (i.e. soil and sediment) and bio-shielding concrete from decommissioning of nuclear reactor were carried out by dynamic sequential extraction using an on-line sequential injection (SI) system combined with a specially...... designed extraction column. Plutonium in the fractions from the sequential extraction was separated by ion exchange chromatography and measured using alpha spectrometry. The analytical results show a higher mobility of plutonium in bio-shielding concrete, which means attention should be paid...

  2. Activation of the concrete in the bio shield of ITER

    International Nuclear Information System (INIS)

    Calculations of neutron spectra in different parts of the tokamak building of ITER are performed. A computational geometry model of the tokamak building is prepared using MCNP-4C. The model includes adequate material composition and geometry description of the main parts of the tokamak for PPCS plant model A: toroidal field coils, vacuum vessel, shield, blanket structure, first wall, divertor, 14.1 MeV neutron source. The design and the dimensions of the bio shield are taken from the current ITER design. MCNP calculations of the neutron spectra in the bio shield (concrete) of ITER are performed, using the neutron spectra in TF coils calculated at UKAEA as external neutron source. The neutron spectra in the concrete calculated by MCNP are used as input data in the code EASY99 for estimations of the activation of the concrete in the bio shield around the tokamak. The time evolutions of the maximum (in the bio shield floor) and minimum (in the bio shield side walls) specific activity (Bq/kg) and dose rate (Sv/h.) of the main dominant nuclides in the concrete are evaluated and compared for 3 different concrete types, used as biological shield in the PWR and BR3 reactors. (author)

  3. Tests on standard concrete samples

    CERN Multimedia

    CERN PhotoLab

    1973-01-01

    Compression and tensile tests on standard concrete samples. The use of centrifugal force in tensile testing has been developed by the SB Division and the instruments were built in the Central workshops.

  4. Shielding analysis for ITER equatorial bio-shield plug

    International Nuclear Information System (INIS)

    ITER equatorial port cell outside bio-shield plug is a place for allowing free personnel access after shutdown which accommodates various sensitive equipment and pipes. To ensure the personnel safety in port cell after shutdown, the distribution of dose rate in port cell was studied. Based on VisualBUS (CAD-Based Multi-Functional 4D Neutronics Simulation System), dose rate calculations were completed in port cell after shutdown. The result showed that dose rates in port cell are still 2 orders of magnitude more than desired limit (10 μSv/h) after one day shutdown. The optimization of bio-shield was needed. (authors)

  5. Concrete sample point: 304 Concretion Facility

    International Nuclear Information System (INIS)

    This report contains information concerning the analysis of concretes for volatile organic compounds. Included are the raw data for these analysis and the quality control data, the standards data, and all of the accompanying chains-of-custody records and requests for special analysis

  6. Concrete sample point: 304 Concretion Facility

    Energy Technology Data Exchange (ETDEWEB)

    Rollison, M.D.

    1995-03-10

    This report contains information concerning the analysis of concretes for volatile organic compounds. Included are the raw data for these analysis and the quality control data, the standards data, and all of the accompanying chains-of-custody records and requests for special analysis.

  7. Measurement of neutron activation in concrete samples

    International Nuclear Information System (INIS)

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

  8. Concrete samples for organic samples, data package and 222-S validation summary report. Addendum 1A

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, R.E.

    1994-11-01

    This document is in two parts: the first is the data package entitled ``Concrete Samples for Organic Samples`` and the second is entitled ``Concrete Samples for Organic Samples -- Addendum 1A`` which is the 222-S validation summary report.

  9. Non-destructive evaluation of concrete samples using PGNAA technique

    International Nuclear Information System (INIS)

    Non-destructive evaluation of concrete is an important task of quality control in building construction industry. The quality evaluation of concrete samples was carried out using prompt gamma ray activation analysis (PGNAA) technique. In this study calcium and silicon contents of six concrete samples were determined through yield of 1.94 MeV gamma-rays from calcium and 3.54 MeV gamma-rays from silicon. The concrete samples were prepared by mixing cement, coarse and fine aggregates in different proportions. A linear correlation has been observed between the experimental yield of the prompt gamma rays and the actual calcium and silicon concentration in the concrete samples. Results of this study have demonstrated successful use of an accelerator-based PGNAA setup in non-destructive analysis of the concrete samples. (author)

  10. A Multi-Phased Sampling Effort to Characterize a University TRIGA Research Reactor

    International Nuclear Information System (INIS)

    A radiological characterization project was conducted at the University of Illinois (University) TRIGA research nuclear reactor in July 2005 as part of the long-term facility decommissioning project. The characterization effort included multiple survey and sampling techniques designed to assess both contamination of the reactor building and equipment and activation of reactor components and the reactor bio-shield. Radiation measurements included alpha and beta surface contamination measurements, gamma dose rate measurements, and gross gamma radiation measurements. Modeling was conducted based on the field measurements to predict concentrations of activation products in reactor components that were not directly sampled. The sampling effort included collecting removable contamination swipes, concrete samples from the reactor room floor and bio-shield, soil samples from below and around the perimeter of the reactor building, graphite samples from graphite moderator, and metal samples from reactor components. Concrete samples were obtained using an innovative technology that allowed for quick sample collection and analysis. Concrete, soil, graphite, and metal samples were analyzed on-site using liquid scintillation counters and gamma spectroscopy. Additional samples were sent off-site for analysis. (authors)

  11. Leaching performance of concrete based on studies of samples from old concrete constructions

    International Nuclear Information System (INIS)

    Concrete will be used for different purposes in the underground repositories for radioactive waste according to the Swedish concept. Cementitious materials are unstable in groundwater. Thus it is important to be able to model and calculate the degradation and the effect of the degradation on the groundwater composition. Concrete is a porous material and consists of solid phases in contact and in equilibrium with a pore water solution. The progress of degradation can be expressed in terms of water exchange cycles or speed of diffusion of ions in the pore solution. In dense concrete, or submerged concrete, the water exchange will mainly be ruled by diffusion and controlled by concentration gradient. Diffusion controlled leaching is presumably the ruling mechanism that will effect the concrete when the repository is closed and saturated with groundwater. The mechanisms and parameters behind diffusion leaching are discussed in the report. Earlier work on leaching has mainly been based on accelerated experiments and theory. In this report we have linked it to natural analogues to get a better and more realistic value for the speed of degradation and the influence of natural water. We have investigated a sequence of old concrete water basins from the Norsborg water works outside Stockholm. The basins, which were of different quality, were cast in 1910, 1916, 1927, 1944 and 1960. Samples were taken and the concrete was investigated in detail in polarising microscope, SEM and NMR. This has given both the texture and the changes of chemistry in the different phases of the cement paste. The paste has developed a characteristic zonal pattern with a progressive decalcification of the cement paste, coupled to carbonation and absorption of Mg ions at the surface. This material is complemented with some analyses of submerged parts of bridges. The physical properties of the alteration zone and the local concentration of ions in the different alteration zones control the diffusion

  12. Inspection of reinforced concrete samples by Compton backscattering technique

    Science.gov (United States)

    Boldo, E. M.; Appoloni, C. R.

    2014-02-01

    Reinforced concrete structures require frequent monitoring to ensure the concrete quality during its service life and for evaluation of in situ existing conditions. Compton backscattering of gamma rays is a nondestructive technique used for material characterization and detection of defects and inclusions in materials and can be employed on reinforced concrete. The methodology allows one-sided inspection of large structures, is relatively inexpensive and can be portable. The concept is based on detection of backscattered radiation produced from a collimated beam aimed at the sample. By measuring the spectrum of these scattered gamma rays it is possible to determine local density perturbations. In this work we used the Compton backscattering technique to locate and measure steel, defects and crushed stone inside concrete. The samples were irradiated with gamma rays from a Ø2 mm diameter collimated 241Am (100 mCi) source and the inelastically scattered photons were recorded at an angle of 135° by a high resolution CdTe semiconductor detector. Scanning was achieved by lateral movement of the sample blocks across the source and detector field of view in steps of 1 mm. A previous optimization of the experimental setup was performed with Monte Carlo simulation. The results showed that it was possible to locate inclusions and defects with Ø8 mm positioned at a depth of 20 mm below the surface of the sample. It was observed that aggregates such as crushed stone could mask defects at specific points due to high attenuation of the incident and scattered beam.

  13. Inspection of reinforced concrete samples by Compton backscattering technique

    International Nuclear Information System (INIS)

    Reinforced concrete structures require frequent monitoring to ensure the concrete quality during its service life and for evaluation of in situ existing conditions. Compton backscattering of gamma rays is a nondestructive technique used for material characterization and detection of defects and inclusions in materials and can be employed on reinforced concrete. The methodology allows one-sided inspection of large structures, is relatively inexpensive and can be portable. The concept is based on detection of backscattered radiation produced from a collimated beam aimed at the sample. By measuring the spectrum of these scattered gamma rays it is possible to determine local density perturbations. In this work we used the Compton backscattering technique to locate and measure steel, defects and crushed stone inside concrete. The samples were irradiated with gamma rays from a Ø2 mm diameter collimated 241Am (100 mCi) source and the inelastically scattered photons were recorded at an angle of 135° by a high resolution CdTe semiconductor detector. Scanning was achieved by lateral movement of the sample blocks across the source and detector field of view in steps of 1 mm. A previous optimization of the experimental setup was performed with Monte Carlo simulation. The results showed that it was possible to locate inclusions and defects with Ø8 mm positioned at a depth of 20 mm below the surface of the sample. It was observed that aggregates such as crushed stone could mask defects at specific points due to high attenuation of the incident and scattered beam. - Highlights: ► Compton Backscattering was used to inspect reinforced concrete samples. ► The positioning of rebars, defects and crushed stone was achieved. ► High attenuation presented by crushed stone can mask defects at specific points

  14. Concrete crushing and sampling, a methodology and technology for the unconditional release of concrete material from decommissioning

    International Nuclear Information System (INIS)

    Belgoprocess started the industrial decommissioning of the main process building of the former Eurochemic reprocessing plant in 1990, after completion of a pilot project. Two small storage buildings for final products from reprocessing were dismantled to verify the assumptions made in a previous paper study on decommissioning, to demonstrate and develop dismantling techniques and to train personnel. Both buildings were emptied and decontaminated to background levels. They were demolished and the remaining concrete debris was disposed of as industrial waste and green field conditions restored. Currently, the decommissioning operations carried out at the main building have made substantial progress. They are executed on an industrial scale. In view of the final demolition of the building, foreseen to start in the middle of 2008, a clearance methodology for the concrete from the cells into the Eurochemic building has been developed. It considers at least one complete measurement of all concrete structures and the removal of all detected residual radionuclides. This monitoring sequence is followed by a controlled demolition of the concrete structures and crushing of the resulting concrete parts to smaller particles. During the crushing operations, metal parts are separated from the concrete and representative concrete samples are taken. The frequency of sampling meets the prevailing standards. In a further step, the concrete samples are milled, homogenised, and a smaller fraction is sent to the laboratory for analyses. The paper describes the developed concrete crushing and sampling methodology. (authors)

  15. 1995 Phase 1 concrete sampling at the decontaminated 183-H basins

    International Nuclear Information System (INIS)

    This report provides a consolidated reference for 1995 concrete sampling data associated with the Hanford Site's 183-H Solar Evaporation Basins (located at the Hanford Site in Richland, Washington). In 1995, the basins were decontaminated and dismantled. Sampling efforts began after completion of concrete decontamination efforts. Soil and water samples were collected and are described in chronological order in this report

  16. Elemental analysis of concrete samples using an accelerator-based PGNAA setup

    Science.gov (United States)

    Naqvi, A. A.; Nagadi, M. M.; Baghabra Al-Amoudi, Omar S.

    2004-09-01

    Elemental analysis of concrete samples was carried out using an accelerator-based prompt gamma ray neutron activation analysis (PGNAA) setup. The gamma rays were produced via the capture of thermal neutron in the concrete sample. The prompt gamma ray yield was measured for 12 cm long concrete samples as a function of sample radius over a range of 6-11.5 cm radii. The optimum yield of the prompt gamma rays from the concrete sample was measured from a sample with 11.5 cm radius. The gamma ray yield was also calculated for 12 cm long concrete samples with 6-11.5 cm radius using Monte Carlo simulations. The experimental results were in excellent agreement with the calculated yield of the prompt gamma rays from the samples. Result of this study has shown the useful application of an accelerator-based PGNAA setup in elemental analysis of concrete sample. The facility can be further used to determine the chloride and sulfate concentrations in concrete samples for corrosion studies of reinforcement steel in concrete structures.

  17. Elemental analysis of concrete samples using an accelerator-based PGNAA setup

    International Nuclear Information System (INIS)

    Elemental analysis of concrete samples was carried out using an accelerator-based prompt gamma ray neutron activation analysis (PGNAA) setup. The gamma rays were produced via the capture of thermal neutron in the concrete sample. The prompt gamma ray yield was measured for 12 cm long concrete samples as a function of sample radius over a range of 6-11.5 cm radii. The optimum yield of the prompt gamma rays from the concrete sample was measured from a sample with 11.5 cm radius. The gamma ray yield was also calculated for 12 cm long concrete samples with 6-11.5 cm radius using Monte Carlo simulations. The experimental results were in excellent agreement with the calculated yield of the prompt gamma rays from the samples. Result of this study has shown the useful application of an accelerator-based PGNAA setup in elemental analysis of concrete sample. The facility can be further used to determine the chloride and sulfate concentrations in concrete samples for corrosion studies of reinforcement steel in concrete structures

  18. Monitoring, Modeling, and Diagnosis of Alkali-Silica Reaction in Small Concrete Samples

    Energy Technology Data Exchange (ETDEWEB)

    Agarwal, Vivek [Idaho National Lab. (INL), Idaho Falls, ID (United States); Cai, Guowei [Idaho National Lab. (INL), Idaho Falls, ID (United States); Gribok, Andrei V. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mahadevan, Sankaran [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-09-01

    Assessment and management of aging concrete structures in nuclear power plants require a more systematic approach than simple reliance on existing code margins of safety. Structural health monitoring of concrete structures aims to understand the current health condition of a structure based on heterogeneous measurements to produce high-confidence actionable information regarding structural integrity that supports operational and maintenance decisions. This report describes alkali-silica reaction (ASR) degradation mechanisms and factors influencing the ASR. A fully coupled thermo-hydro-mechanical-chemical model developed by Saouma and Perotti by taking into consideration the effects of stress on the reaction kinetics and anisotropic volumetric expansion is presented in this report. This model is implemented in the GRIZZLY code based on the Multiphysics Object Oriented Simulation Environment. The implemented model in the GRIZZLY code is randomly used to initiate ASR in a 2D and 3D lattice to study the percolation aspects of concrete. The percolation aspects help determine the transport properties of the material and therefore the durability and service life of concrete. This report summarizes the effort to develop small-size concrete samples with embedded glass to mimic ASR. The concrete samples were treated in water and sodium hydroxide solution at elevated temperature to study how ingress of sodium ions and hydroxide ions at elevated temperature impacts concrete samples embedded with glass. Thermal camera was used to monitor the changes in the concrete sample and results are summarized.

  19. Moisture profile measurements of concrete samples in vertical water flow by gamma ray transmission method

    International Nuclear Information System (INIS)

    Samples of concrete for popular habitation (0.1x0.03x0.1 m) and cellular concrete (0.1x0.05x0.1 m) were submitted to water vertical ascending infiltration. The moisture content spatial and temporal evolution of each sample it was monitored in three halfway positions in a same horizontal line, applying the gamma rays transmission method. The data were taken with a 137Cs (3.7x1010 Bq, 0662 MeV) source, NaI (Tl) of 2x2'' detector coupled to gamma ray spectrometry standard electronic with multichannel analyzer and a micrometric table. For the popular habitation concrete, there was a clear correlation between wetting profiles and concrete strength. The cellular concrete showed a wetting profile compatible to its greater porosity. (author)

  20. Moisture profile measurements of concrete samples in vertical water flow by gamma ray transmission method

    Science.gov (United States)

    da Rocha, M. C.; da Silva, L. M.; Appoloni, C. R.; Portezan Filho, O.; Lopes, F.; Melquíades, F. L.; dos Santos, E. A.; dos Santos, A. O.; Moreira, A. C.; Pötker, W. E.; de Almeida, E.; Tannous, C. Q.; Kuramoto, R.; Cavalcante, F. H. de M.; Barbieri, P. F.; Caleffi, A. F.; Carbonari, B. T.; Carbonari, G.

    2001-06-01

    Samples of concrete for popular habitation (0.1×0.03×0.1 m) and cellular concrete (0.1×0.05×0.1 m) were submitted to water vertical ascending infiltration. The moisture content spatial and temporal evolution of each sample it was monitored in three halfway positions in a same horizontal line, applying the gamma rays transmission method. The data were taken with a 137Cs (3.7×1010 Bq, 0662 MeV) source, Nal (Tl) of 2×2″ detector coupled to gamma ray spectrometry standard electronic with multichannel analyzer and a micrometric table. For the popular habitation concrete, there was a clear correlation between wetting profiles and concrete strength. The cellular concrete showed a wetting profile compatible to its greater porosity.

  1. Phase 1 sampling and analysis plan for the 304 Concretion Facility closure activities

    International Nuclear Information System (INIS)

    This document provides guidance for the initial (Phase 1) sampling and analysis activities associated with the proposed Resource Conservation and Recovery Act of 1976 (RCRA) clean closure of the 304 Concretion Facility. Over its service life, the 304 Concretion Facility housed the pilot plants associated with cladding uranium cores, was used to store engineering equipment and product chemicals, was used to treat low-level radioactive mixed waste, recyclable scrap uranium generated during nuclear fuel fabrication, and uranium-titanium alloy chips, and was used for the repackaging of spent halogenated solvents from the nuclear fuels manufacturing process. The strategy for clean closure of the 304 Concretion Facility is to decontaminate, sample (Phase 1 sampling), and evaluate results. If the evaluation indicates that a limited area requires additional decontamination for clean closure, the limited area will be decontaminated, resampled (Phase 2 sampling), and the result evaluated. If the evaluation indicates that the constituents of concern are below action levels, the facility will be clean closed. Or, if the evaluation indicates that the constituents of concern are present above action levels, the condition of the facility will be evaluated and appropriate action taken. There are a total of 37 sampling locations comprising 12 concrete core, 1 concrete chip, 9 soil, 11 wipe, and 4 asphalt core sampling locations. Analysis for inorganics and volatile organics will be performed on the concrete core and soil samples. Separate concrete core samples will be required for the inorganic and volatile organic analysis (VOA). Analysis for inorganics only will be performed on the concrete chip, wipe, and asphalt samples

  2. Ballistic penetration test results for Ductal and ultra-high performance concrete samples.

    Energy Technology Data Exchange (ETDEWEB)

    Reinhart, William Dodd; Thornhill, Tom Finley, III (KTech)

    2010-03-01

    This document provides detailed test results of ballistic impact experiments performed on several types of high performance concrete. These tests were performed at the Sandia National Laboratories Shock Thermodynamic Applied Research Facility using a 50 caliber powder gun to study penetration resistance of concrete samples. This document provides test results for ballistic impact experiments performed on two types of concrete samples, (1) Ductal{reg_sign} concrete is a fiber reinforced high performance concrete patented by Lafarge Group and (2) ultra-high performance concrete (UHPC) produced in-house by DoD. These tests were performed as part of a research demonstration project overseen by USACE and ERDC, at the Sandia National Laboratories Shock Thermodynamic Applied Research (STAR) facility. Ballistic penetration tests were performed on a single stage research powder gun of 50 caliber bore using a full metal jacket M33 ball projectile with a nominal velocity of 914 m/s (3000 ft/s). Testing was observed by Beverly DiPaolo from ERDC-GSL. In all, 31 tests were performed to achieve the test objectives which were: (1) recovery of concrete test specimens for post mortem analysis and characterization at outside labs, (2) measurement of projectile impact velocity and post-penetration residual velocity from electronic and radiographic techniques and, (3) high-speed photography of the projectile prior to impact, impact and exit of the rear surface of the concrete construct, and (4) summarize the results.

  3. Measurement of the wetting profile in concrete samples with vertical water by gamma radiation transmission method

    International Nuclear Information System (INIS)

    Samples of concrete for popular habitation (0,1x0,03x0,1 m) and cellular concrete (0,1x0,05x0,1 m) were submitted to water vertical ascending infiltration. The moisture content spatial and temporal evolution of each sample it was monitored in three halfway positions in a same horizontal line, applying the gamma rays transmission method. The data were taken with a 137Cs (3,7x1010 Bq, 0662 MeV) source, NaI (Tl) of 2x2' detector coupled to between wetting profiles and concrete strength. The cellular concrete showed a wetting profile compatible to its greater porosity. (author)

  4. Rapid radiochemical method for determination of actinides in emergency concrete and brick samples

    International Nuclear Information System (INIS)

    Highlights: → A rapid fusion method was tested on concrete and brick samples. → Actinides were determined rapidly using the fusion plus extraction chromatography and alpha spectrometry. → Stacked TEVA, TRU and DGA rein cartridges were used with rapid flow rates. → High chemical yields, effective removal of interferences and very good results were obtained. - Abstract: A new rapid method for the determination of actinides in emergency concrete and brick samples has been developed at the Savannah River Site Environmental Lab (Aiken, SC, USA) that can be used in emergency response situations or for routine analysis. If a radiological dispersive device (RDD), Improvised Nuclear Device (IND) or nuclear accident occurs, there will be a urgent need for rapid analyses of many different environmental matrices, including building materials such as concrete and brick, to support dose mitigation and environmental clean-up. The new method for actinides in concrete and brick method utilizes a rapid sodium hydroxide fusion method, a lanthanum fluoride matrix removal step, and a column separation process with stacked TEVA, TRU and DGA Resin cartridges. Alpha emitters are prepared using rare earth microprecipitation for counting by alpha spectrometry. The method showed high chemical recoveries and effective removal of interferences. The determination of actinides in concrete and brick sample analysis can be performed in less than 8 h with excellent quality for emergency samples. The rapid fusion technique is a rugged sample digestion method that ensures that any refractory actinide particles are effectively digested.

  5. Process and effects of Project BioShield%美国生物盾牌计划的完善进程及实施效果

    Institute of Scientific and Technical Information of China (English)

    吉荣荣; 雷二庆; 徐天昊

    2013-01-01

    The US Project BioShield is a ten-year plan to respond to chemical, biological, radiological and nuclear (CBRN) threat agents. So far, the US government has appropriated $ 5. 567billion for the program. The development and acquisitions under Project BioShield are vaccines and therapeutic drugs which are used to address each of the above 4 threat agents, including Bacillus anthracis( anthrax) .smallpox virus, botulinum toxins, chemical and radiological agents. The implementation of Project BioShield has improved the ability to respond to CBRN terrorist attacks, promoted the development and transfer of basic research products and preclinical development, and enhanced the management system of biodefense scientific research.%生物盾牌计划是美国应对核化生放(CBRN)等大规模杀伤性武器威胁的一项十年计划.截至目前,生物盾牌计划共获拨款55.67亿美元,研发并储备了炭疽芽孢杆菌、天花病毒、肉毒毒素疫苗以及化学、放射和核损伤的治疗药物.生物盾牌计划的实施提升了美国应对CBRN恐怖袭击能力,促进了生物医药基础研究和临床前期产品的研发与转化,推动了美国生物防御体系的完善.

  6. Change Of Electrical Resistivity Depending On Water Saturation Of The Concrete Samples

    Science.gov (United States)

    Sabbaǧ, Nevbahar; Uyanık, Osman

    2016-04-01

    In this study, the changes of electrical apparent resistivity values depending on the water saturation of cubic concrete samples which designed according to different strength were investigated. For this purpose, 3 different concrete design as poor, middle and good strength 150x150x150mm dimensions 9 for each design cubic samples were prepared. After measuring the weight of the prepared samples, in oven were dried at 105 ° C for 24 hours and then the dry weights were measured. Then the samples were placed into the curing pool and saturated weight of the samples were measured in specific time periods during the 90 day take out from the curing pool and the water content were calculated at each stage of these processes. The water content of the samples were obtained during 90 days specific points in time and as well as electrical apparent resistivity method of the different surfaces of the samples the potential difference measurements made by electrical resistivity method and electrical apparent resistivity values of the samples were calculated. Depending on time obtained from this study with respect to time curves of the water content and the apparent resistivity values were constructed. Results showed that the electrical apparent resistivity values increased depends on the water content. This study was supported with OYP05277-DR-14 Project No. by SDU and State Hydraulic Works 13th Regional/2012-01 Project No. Keywords: Concrete, cubic sample, Resistivity, water content, time

  7. A method for disaggregating clay concretions and eliminating formalin smell in the processing of sediment samples

    DEFF Research Database (Denmark)

    Cedhagen, Tomas

    1989-01-01

    A complete handling procedure for processing sediment samples is described. It includes some improvements of conventional methods. The fixed sediment sample is mixed with a solution of the alkaline detergent AJAX® (Colgate-Palmolive). It is kept at 80-900 C for 20-40 min. This treatment facilitat...... subsequent sorting as it disaggregates clay concretions and faecal pellets ·but leaves even fragile organisms clean and unaffected. The ammonia in the detergent eliminates the formalin smell....

  8. NANO-TESTS OF CONCRETE SAMPLES WITH AND WITHOUT NANO-TUBES

    OpenAIRE

    B. Khroustalev; Eberhardsteiner, J.; O. Lahayn; S. Leonovich; G. Yakovlev; G. Pervushin

    2014-01-01

    The concrete samples originate from fracture mechanics tests performed on February 19, 2012, at the Department of Geo-Engineering and Building Materials of the Izhevsk State Technical University.After the fracture mechanics tests three types of small specimens (marked with CNT, C3 and control sample) have been prepared and tested by means of Nano-Indentation (NI) and Atomic Force Microscopy (AFM), at the Institute for Mechanics of Materials and Structures and Institute of Automation and Contr...

  9. Determination of Mass Attenuation Coefficients of Some Gas Concrete Samples Used As Building Materials in Turkey

    International Nuclear Information System (INIS)

    The goal of this work was to measure the mass attenuation coefficients of some gas concrete samples used as building materials in Turkey. The mass attenuation coefficients (μ/ρ) of six different gas concrete samples were determined for the twelve energies. The samples were irradiated by photons emitted from 109Cd, 57Co, 133Ba, 54Mn, 137Cs, 60Co and 22Na radioactive sources in the energy range of 88 and 1332.5 keV. The measurements were performed by using gamma spectrometry with a high purity Ge detector of 55% relative efficiency and resolution of 1.9 keV at 1332 keV gamma of 60Co

  10. Distribution of natural radioactive isotope concentrations and emanation factors measured on concrete and brick samples produced in Hungary

    International Nuclear Information System (INIS)

    Natural radioactive isotope concentrations and emanation factors were measured on concrete and brick samples produced in different parts of Hungary. The natural activity parameters measured on samples produced in a given factory within a period of 1 to 2 years show normal distribution. Samples received at different times from all the building factories under investigation showed about half normal and half lognormal distributions of natural activity parameters. Calculating with the arithmetical means obtained for each of the natural activities substituted into simple models, it was found that the radon and thoron activity is expected to increase by about 25% and the exposure from external radiation to decrease by a factor of 2.3 in the new prefabricated apartments made of concrete as compared with the conventional apartments with brick walls and concrete ceilings. The data obtained from the measurements were used to establish reference levels for the radiological grading of concrete and brick produced in Hungary

  11. Development of a new bench for measuring gas diffusion through concrete samples representative of nuclear waste containers

    International Nuclear Information System (INIS)

    CEA's Process Cycle Advanced Technology Laboratory has developed a dedicated test bench called BANDY for gaseous diffusion through concrete. The objective is to test diffusion phenomena on representative sample size and also in an industrial environment. The size of samples allows us to test reinforced concrete using metallic fibers and reinforced bars in the same casting conditions as in an industrial environment. This approach requires the development of a new experimental device to integrate the size of samples and an environment close to the storage conditions. The capacity of concrete to transport gas depends partially on its degree of water saturation. For a better understanding of water saturation effects on concrete and gaseous transfer by diffusion, relative humidity sensors were set into the mould before casting. The arrangement of these sensors in a sample has enabled us to follow hydric evolution within the time of the concrete and to better understand hydric diffusion between the middle and the edges. First, this paper describes the new diffusion device which allows the measurement of the diffusion coefficients and how the gas flows under storage conditions. The innovative nature of the device comes from its leak-tightness system. Different operating processes are explained and the experimental limits are given. The relative humidity sensors (coated on concrete samples during their manufacture) are described. Secondly, results obtained using different concrete formulations are presented with different moisture levels. Finally, the diffusion measurements of gases are presented. Two types of diffusion measurement enable the materials to be characterized: the diffusion coefficient and the gas flow evacuated for different concentrations of hydrogen. The latter experimental device is close to operating conditions: sample with upper surface in contact with the outside and lower sur face compartment fed with the gas to be transported. In conclusion, the

  12. Concrete and abstract thinking styles and art preferences in a sample of serious art collectors.

    Science.gov (United States)

    Gridley, Mark C

    2006-06-01

    59 art collectors (30 men, 29 women) were given the Gregorc Style Delineator to classify them by thinking styles and a questionnaire regarding their art preferences. Their ages ranged from 33 to 99 years (M=59.5 yr.). Abstract art was preferred by 34% of the sample. Representational art, such as Dutch Masters and Impressionism, was preferred by 66% of the sample. Of the collectors who preferred nonobjective abstract paintings, such as works by color field artists like Mark Rothko, and Abstract Expressionist paintings, such as works by Jackson Pollock, 62% had scores on the Gregorc Style Delineator by which they were classified as showing abstract thinking styles. Of the collectors who preferred representational painting, 86% were classified as showing concrete thinking styles. PMID:16933684

  13. Applying high resolution SyXRD analysis on sulfate attacked concrete field samples

    International Nuclear Information System (INIS)

    High resolution synchrotron X-ray diffraction (SyXRD) was applied for a microstructural profile analysis of concrete deterioration after sulfate attack. The cement matrices consist of ordinary Portland cement and different amounts of supplementary cementitious materials, such as fly ash, natural pozzolana and granulated blast furnace slag. The changes of the phase composition were determined along the direction of sulfate ingress. This approach allows the identification of reaction fronts and zones of different phase compositions and conclusions about the mechanisms of sulfate attack. Two reaction fronts were localized in the initial 4 mm from the sample surface. The mechanism of deterioration caused by the exposition in the sulfate-bearing soil is discussed. SyXRD is shown to be a reliable method for investigation of cementitious materials with aggregates embedded in natural environments

  14. Applying high resolution SyXRD analysis on sulfate attacked concrete field samples

    Energy Technology Data Exchange (ETDEWEB)

    Stroh, J. [BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Straße 11, 12489 Berlin (Germany); Schlegel, M.-C. [BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Straße 11, 12489 Berlin (Germany); Helmholtz-Zentrum Berlin (HZB), Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Irassar, E.F. [Department of Civil Engineering, National University of Buenos Aires Center State, Avenida Del Valle 5737, B7400JWI Olavarría (Argentina); Meng, B. [BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Straße 11, 12489 Berlin (Germany); Emmerling, F., E-mail: franziska.emmerling@bam.de [BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Straße 11, 12489 Berlin (Germany)

    2014-12-15

    High resolution synchrotron X-ray diffraction (SyXRD) was applied for a microstructural profile analysis of concrete deterioration after sulfate attack. The cement matrices consist of ordinary Portland cement and different amounts of supplementary cementitious materials, such as fly ash, natural pozzolana and granulated blast furnace slag. The changes of the phase composition were determined along the direction of sulfate ingress. This approach allows the identification of reaction fronts and zones of different phase compositions and conclusions about the mechanisms of sulfate attack. Two reaction fronts were localized in the initial 4 mm from the sample surface. The mechanism of deterioration caused by the exposition in the sulfate-bearing soil is discussed. SyXRD is shown to be a reliable method for investigation of cementitious materials with aggregates embedded in natural environments.

  15. Monitoring of a Large Cracked Concrete Sample with Non-Linear Mixing of Ultrasonic Coda Waves

    OpenAIRE

    Abraham, Odile; ZHANG, Yuxiang; Chapeleau, Xavier; Durand, Olivier; Tournat, Vincent

    2014-01-01

    A high precision can be achieved with ultrasonic coda waves to monitor the mechanical properties of concrete material (~10-5 in relative). This high sensitivity can be used to detect damage initiation and to closely follow concrete mechanical properties evolution with time. This advantage is counterbalance by the influence of environmental conditions making reproducibility of any experiment in concrete a challenging issue especially when in situ measurements are performed. Indeed thermal and ...

  16. Influence of aggregate shapes on drying and carbonation phenomena in 3D concrete numerical samples

    International Nuclear Information System (INIS)

    This study aims at generating numerical 3D samples of concrete so as to study the effects of the granular inclusions shape on the macroscopic kinetics of reactive transport phenomena. Two types of meso-structure configurations are considered: the first one is composed of a matrix of mortar in which are randomly distributed inclusions corresponding to the concrete coarse aggregates, and the second one also includes a steel rebar. The choice of a mesoscopic modeling for the mortar matrix is based on the need to obtain numerical structures of reasonable size. In particular, the Interfacial Transition Zones (ITZs) are assumed to be incorporated into the homogenized mortar properties. This study is applied to the case of drying and atmospheric carbonation by using simplified models solved by the finite element code Cast3M. The purpose is to quantify the influence of the aggregate shape on the kinetics of macroscopic transfer and the iso-value lines for some physical variables representative of the reactive transport problems: saturation degree for drying, and porosity, calcite and portlandite concentrations for carbonation. Basic aggregates shapes are studied (spheres, cubes), as well as more complex ones (Voronoi particles) which are supposed to be more representative of real aggregates. The effects of 'non-isotropic' shapes (oblate and prolate ones) are also investigated. It is shown that the influence of the aggregate shapes appears negligibly small on macroscopic indicators, except for oblate shapes with aspect ratios of 3. This latter case also exhibits substantial local delayed effects and a more important variability, which may have some importance for a precise description and estimation of degradation processes related to steel rebar corrosion. (authors)

  17. Non destructive multi elemental analysis using prompt gamma neutron activation analysis techniques: Preliminary results for concrete sample

    International Nuclear Information System (INIS)

    In this study, principle of prompt gamma neutron activation analysis has been used as a technique to determine the elements in the sample. The system consists of collimated isotopic neutron source, Cf-252 with HPGe detector and Multichannel Analysis (MCA). Concrete with size of 10×10×10 cm3 and 15×15×15 cm3 were analysed as sample. When neutrons enter and interact with elements in the concrete, the neutron capture reaction will occur and produce characteristic prompt gamma ray of the elements. The preliminary result of this study demonstrate the major element in the concrete was determined such as Si, Mg, Ca, Al, Fe and H as well as others element, such as Cl by analysis the gamma ray lines respectively. The results obtained were compared with NAA and XRF techniques as a part of reference and validation. The potential and the capability of neutron induced prompt gamma as tool for multi elemental analysis qualitatively to identify the elements present in the concrete sample discussed

  18. Analysis of Powder Samples Extracted from Concrete Structures of Nuclear Plant

    Czech Academy of Sciences Publication Activity Database

    Zatloukal, J.; Bezdička, Petr

    Zurich : Trans Tech Publications Ltd, 2014, s. 1-5. ISBN 978-3-03835-317-1. ISSN 1022-6680. - (Advanced Materials Research. 1054). [International Conference on Special Concrete and Composites/11./. Lísek (CZ), 16.10.2014-17.10.2014] Institutional support: RVO:61388980 Keywords : Civil structures of nuclear plants * TG/DTA * XRD * XRF Subject RIV: CA - Inorganic Chemistry

  19. Concrete Thinking

    OpenAIRE

    Kuang-Ming Wu

    2015-01-01

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

  20. Radiation effects in concrete for nuclear power plants – Part I: Quantification of radiation exposure and radiation effects

    International Nuclear Information System (INIS)

    Highlights: • Neutron and gamma rays fields in concrete biological shield are calculated. • An extensive database on irradiated concrete properties has been collected. • Concrete mechanical properties decrease beyond 1.0 × 1019 n/cm2 fluence. • Loss of properties appears correlated with radiation induced-aggregate swelling. • Commercial reactor bio-shield may experience long-term irradiation damage. - Abstract: A large fraction of light water reactor (LWR) construction utilizes concrete, including safety-related structures such as the biological shielding and containment building. Concrete is an inherently complex material, with the properties of concrete structures changing over their lifetime due to the intrinsic nature of concrete and influences from local environment. As concrete structures within LWRs age, the total neutron fluence exposure of the components, in particular the biological shield, can increase to levels where deleterious effects are introduced as a result of neutron irradiation. This work summarizes the current state of the art on irradiated concrete, including a review of the current literature and estimates the total neutron fluence expected in biological shields in typical LWR configurations. It was found a first-order mechanism for loss of mechanical properties of irradiated concrete is due to radiation-induced swelling of aggregates, which leads to volumetric expansion of the concrete. This phenomena is estimated to occur near the end of life of biological shield components in LWRs based on calculations of estimated peak neutron fluence in the shield after 80 years of operation

  1. 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,…

  2. A historical examination of concrete

    International Nuclear Information System (INIS)

    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

  3. Radiochemical analysis of 90Sr, 41Ca, 129I and 36Cl in waste samples

    International Nuclear Information System (INIS)

    Full text: The decommissioning of a nuclear facility requires estimating the total inventory of radioactivity in various materials and its variation with time, which has to be carried out by the determination of the radioactivity of various radionuclides presented in the materials. Of all materials in the nuclear facilities, graphite, concrete, and steel are the main low-medium radioactive waste due to their large volume. Besides the neutron activation products of components and impurity in the materials including 36Cl and 41Ca, some fission products, such as 90Sr, 99Tc, 129I, and 137Cs also exist in the materials due to the contamination of the leaked nuclear fuel. Of these radionuclides, the determination of gamma emitters is easier and can be directly carried out by gamma spectroscopy without any radiochemical separation. But the beta and alpha emitters including 3H, 14C, 36Cl, 41Ca, 55Fe, 63Ni, 90Sr, 9 and 129I and some transuranics, have to be determined by radiochemical analysis including a completely separation of individual radionuclides from matrix and other radionuclides before measurement by beta counting, alpha spectrometry or mass spectrometry. This work presents radiochemical analytical methods developed in our laboratory in the recent years for the determination of 36Cl, 41Ca, 90Sr and 129I in bio-shielding concrete, graphite and metals. for the decommissioning of nuclear facilities. Besides individual procedure for the purification of various radionuclides, a combined procedure is also developed and presented for the simultaneous determination of all four radionuclides from one sample. (author)

  4. 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

  5. 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

  6. Concrete, hardened: Self desiccation

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place; Hansen, Kurt Kielsgaard; Persson, Bertil

    1999-01-01

    The test method covers the determination of internal relative humidity (RH) in hardened concrete and cement mortar using RH instruments. The determination of RH is done on crushed samples of concrete or cement motar. This test method is only for measuring equipment which gives off or takes up...

  7. 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...

  8. Pervious Concrete

    OpenAIRE

    Torsvik, Øyvind André Hoff

    2011-01-01

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

  9. 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....

  10. Glazed Concrete

    DEFF Research Database (Denmark)

    Bache, Anja Margrethe

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

  11. Distribution of radioactive nuclides of boring core samples extracted from concrete structures of reactor buildings in the Fukushima Daiichi Nuclear Power Plant

    International Nuclear Information System (INIS)

    Since the start of the severe accidents at the Fukushima Daiichi Nuclear Power Plant in March 2011, concrete surfaces within the reactor buildings (RBs) have been exposed to radioactive contaminants. Released radionuclides still remain too high to permit entry into some areas of the RBs to allow the damage to be assessed and to allow carrying out the restoration of lost safety functions, decommissioning activities, etc. In order to clarify the situation of this contamination in the RBs of Units 1, 2 and 3, samples of contaminants were collected and subjected to analyses to determine the surface radionuclide concentrations and to characterize the radionuclide distributions in the samples. Especially, decontamination tests on the boring core sample of Unit 2 were conducted to quantitatively determine the effectiveness of several basic decontamination techniques. As a result of the tests, the level of radioactivity of this sample was reduced with the removal of ∼97% of the contamination present near the sample surface, and it was confirmed for the boring core sample that the contamination mainly had the characteristics of fixed contamination of the surface. (author)

  12. 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.

  13. Concrete = aggregate, cement, water?

    International Nuclear Information System (INIS)

    Concrete for the Temelin nuclear power plant is produced to about 70 different formulae. For quality production, homogeneous properties of aggregates, accurate proportioning devices, technological discipline and systematic inspections and tests should be assured. The results are reported of measuring compression strength after 28 days for different concrete samples. The results of such tests allow reducing the proportion of cement, which brings about considerable savings. Reduction in cement quantities can also be achieved by adding ash to the concrete mixes. Ligoplast, a plasticizer addition is used for improving workability. (M.D). 8 figs

  14. The collection of information, data and materials samples from concrete structures on nuclear facilities under decommissioning for ageing and degradation evaluation

    International Nuclear Information System (INIS)

    The collection of information from nuclear facilities under decommissioning can usefully inform operators of existing plant and designers of new facilities. The evaluation of the performance of concrete structures long after their construction is a relevant safety issue for nuclear installations. Many nuclear facilities are approaching the end of their design life and programmes to extend operating licences have been undertaken to ensure adequate safety levels for extended operational periods and the complete decommissioning phase lasting from a few years up to some decades before dismantling. Ageing management programmes should encompass the full life cycle from conceptual design through to final decommissioning. During decommissioning, dismantling and demolition it is possible to obtain samples from systems, structures and components that have experienced ageing mechanisms in situ and are therefore superior to artificially aged laboratory specimens in informing ageing management programmes and designers of new plant. Such programmes are of value not just to NPPs but also fuel cycle and waste facilities. In order that full benefit may be obtained from the collection of information, data and materials samples from concrete structures on nuclear facilities under decommissioning for ageing and degradation evaluation, these activities must be included in decommissioning plans. In cases where systems, structures and components have been selected for removal, sampling or testing for such purposes, these should be clearly identified and described. This allows specific hazards during these operations to be identified and prevents unintentional loss or destruction of the relevant systems, structures and components during decommissioning. This paper describes the information that may be collected during decommissioning in order to inform plant life management and ageing programmes and new plant designs and the activities required to collect this. Suggestions are also given

  15. Studies of historic concrete

    International Nuclear Information System (INIS)

    Underground concrete repositories for nuclear waste will have to maintain their integrity for hundreds of years. This study examines ancient concretes and assesses the suitability of equivalent modern materials for underground storage. Thirty four ancient samples have been obtained from Great Britain, Austria and Italy. One 19th century sample was also collected. The samples were examined using a variety of analytical techniques (including scanning electron microscopy, optical microscopy, chemical analysis and pH determination). The samples were also subjected to a range of physical tests. Most of the samples examined were very weak and porous although they had retained full structural integrity. With the exception of the 19th century sample, none of the concretes had maintained pH alkaline enough to immobilize radionuclides. Hydrated calcium silicates have been detected in some samples which are similar to those observed in modern Portland cement concretes. These stable cementitious species have endured for almost two thousand years. All the ancient concretes and mortars examined contained natural pozzolanic material or crushed burnt clay. This may have had some effect on the reduction in alkalinity although the main reason was full carbonation of calcium hydroxide

  16. An historical examination of concrete

    International Nuclear Information System (INIS)

    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)

  17. NANOMODIFIED CONCRETE

    Directory of Open Access Journals (Sweden)

    B. M. Khroustalev

    2015-12-01

    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

  18. Use of accelerated aging to predict behavior of recycled materials in concrete pavements. Physical and environmental comparison of laboratory-aged samples with field pavements

    Energy Technology Data Exchange (ETDEWEB)

    Van der Sloot, H.A. [ECN Clean Fossil Fuels, Petten (Netherlands); Eighmy, T.T.; Cook, R.A.; Gress, D.L.; Coviello, A.; Spear, J.C.M. [University of New Hampshire, Durham, NH (United States); Hover, K.; Pinto, R.; Hobbs, S. [Cornell University, Ithaca, NY (United States); Kosson, D.S.; Sanchez, F. [Vanderbilt University, Nashville, TN (United States); Korhonen, C. [US Army Corps of Engineers Cold Regions Research and Engineering Laboratory, Hanover, NH (United States); Simon, M. [Turner-Fairbank Highway Research Center, McLean, VA (United States)

    2002-11-01

    Future behavior of recycled materials in highway applications is often difficult to predict. Accelerated aging is one means of exploring the long-term physical and environmental performance. Coal fly ash (CFA), routinely used as a cementitious replacement in portland cement concrete pavement, was selected as a model system in an accelerated aging approach. US-20 near Fort Dodge, Iowa, was used as a source of field-aged pavement slab material and concrete mixture proportions. This pavement, constructed in 1987, experienced early failure and distress. The role of CFA, if any, in the failure is not known. Three types of accelerated aging treatments were chosen and applied on laboratory prisms made with the US-20 mixture proportions: arrhenius ageing (AA), cyclic loading, and freeze-thaw exposure. Physical and environmental response variables were used to examine the pavement slab and the aged laboratory prisms. The aging protocol affected both physical and chemical properties of the monoliths. It took about 9 months of elapsed time to age specimens to an equivalent age of about 4 years. The equivalent ages matched well with the time frame seen in the field for the onset of early distress. Most response variables for the aged laboratory prisms and the field samples were similar, suggesting that the aging method reasonably produced a pavement of similar age and distress. The AA treatment produced an unexpected loss of strength, suggesting that the accelerated aging promoted the onset of a deleterious reaction. Distinguishing the source of trace metals in leachates was difficult, for all components (CFA, aggregates, cement) had similar elemental compositions and leachability. The use of both physical and environmental response variables showed linkages between compressive strength, microcracking, fine pore structure, Cl diffusive leaching (efflux related to road slating that increases the concentration of Cl in the monolith), and Ca diffusive leaching (related to change

  19. Concrete products

    Energy Technology Data Exchange (ETDEWEB)

    Anon

    2002-01-01

    Increased strength and durability in concrete products can be achieved through the addition of fly ash during the manufacturing process. The properties of concrete are enhanced by fly ash. The benefits include cost and the environment. Fly ash is normally defined as finely divided residue resulting from the combustion of pulverized coal, carried from the combustion chamber to the furnace by exhaust gas. The main applications of fly ash in concrete products are ready mix concrete, bridge decks and support footing, precast structures, blocks and bricks, and pipes. The Canadian Standards Association (CSA) has published standards to ensure that the desired physical properties of the concrete are achieved and the standards are found in CSA A23.1, detailing the engineering materials and mix proportions. The type of fly ash to be used for specific properties is important. Finishing and curing operations must be performed with care. The free lime generated by cement hydration reacts with fly ash, forming additional calcium silicate hydrate. Permeability of the concrete is reduced since the calcium silicate hydrate fills the void resulting from the cement pour. Some of the benefits to be derived from fly ash in concrete are: water reduction, improved workability, high ultimate strength, improved pumpability, and reduced heat of hydration. In addition, the life cycle costs are lower, and great strength is obtained. An environmental benefit results from the reduction of natural resource consumption.

  20. LASER ABLATION STUDIES OF CONCRETE

    Science.gov (United States)

    Laser ablation was studied as a means of removing radioactive contaminants from the surface and near-surface regions of concrete. We present the results of ablation tests on cement and concrete samples using a 1.6 kW pulsed Nd:YAG laser with fiber optic beam delivery. The laser-s...

  1. Drying of Concrete

    DEFF Research Database (Denmark)

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

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

  2. 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 ...

  3. 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.

  4. 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 ...

  5. Comparative Evaluation of Cutting Methods of Activated Concrete from Nuclear Power Plant Decommissioning - 13548

    International Nuclear Information System (INIS)

    The amount of radioactive wastes from decommissioning of a nuclear power plant varies greatly depending on factors such as type and size of the plant, operation history, decommissioning options, and waste treatment and volume reduction methods. There are many methods to decrease the amount of decommissioning radioactive wastes including minimization of waste generation, waste reclassification through decontamination and cutting methods to remove the contaminated areas. According to OECD/NEA, it is known that the radioactive waste treatment and disposal cost accounts for about 40 percentage of the total decommissioning cost. In Korea, it is needed to reduce amount of decommissioning radioactive waste due to high disposal cost, about $7,000 (as of 2010) per a 200 liter drum for the low- and intermediate-level radioactive waste (LILW). In this paper, cutting methods to minimize the radioactive waste of activated concrete were investigated and associated decommissioning cost impact was assessed. The cutting methods considered are cylindrical and volume reductive cuttings. The study showed that the volume reductive cutting is more cost-effective than the cylindrical cutting. Therefore, the volume reductive cutting method can be effectively applied to the activated bio-shield concrete. (authors)

  6. High Performance Concrete (HPC)

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

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

  7. 阿海水电站碾压混凝土长心样取心技术%Coring Technology of Long Core Sample of Roller Compacted Concrete in A’ hai Hydropower Station

    Institute of Scientific and Technical Information of China (English)

    曹琳

    2013-01-01

    A 19.28m complete concrete core sample was successfully removed in RCC dam of A’hai hydropower station. The article introduces the coring technology for long concrete cores in drilling equipment selection, drilling material selec-tion, drilling parameter setting and adjustment, core samples pulling breaking and removing out, core positioning and post maintenance.%  阿海水电站碾压混凝土大坝成功钻取出了一根长19.28 m的完整混凝土心样.从钻孔设备选型、钻孔材料选择、钻进参数制定与调整、心样拔断与提取、出心摆放和后期养护等方面简要介绍了混凝土长心样的取心技术.

  8. 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

  9. Shrinkage of concrete with replacement of aggregate with recycled concrete aggregate

    OpenAIRE

    Gómez Soberón, José Manuel Vicente

    2002-01-01

    In this paper we present the experimental analysis of samples of concrete where portion of the natural aggregate were replaced with recycled aggregate originating from concrete (RCA). Experimental analysis to obtain the shrinkage properties (basic and dried) of the concrete containing recycled concrete aggregate (CRCA) was performed. The percentages of replacement of natural aggregate with RCA were 0%, 15%, 30%, 60% and 100% with test conditions of 50% RH and 20°C. The results of these ...

  10. High Performance Concrete

    OpenAIRE

    Traian Oneţ

    2009-01-01

    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.

  11. Concrete corrosion associated with Thiobacillus (SP - Brazil)

    International Nuclear Information System (INIS)

    The presence of Thiobacillus, heterotrophic bacteria and fungi is investigated in concrete samples from a deteriorated water tank. A sample of the soil which was in contact with the concrete was also evaluated. The thiobacillus isolated were submitted to a growth test. (M.A.C.)

  12. Estimation of Concrete's Porosity by Ultrasounds

    Science.gov (United States)

    Benouis, A.; Grini, A.

    Durability of concrete depends strongly on porosity; this conditions the intensity of the interactions of the concrete with the aggressive agents. The pores inside the concrete facilitate the process of damage, which is generally initiated on the surface. The most used measurement is undoubtedly the measurement of porosity accessible to water. The porosimetry by intrusion with mercury constitutes a tool for investigation of the mesoporosity. The relationship between concrete mixtures, porosity and ultrasonic velocity of concrete samples measured by ultrasonic NDT is investigated. This experimental study is interested in the relations between the ultrasonic velocity measured by transducers of 7.5 mm and 49.5 mm diameter and with 54 kHz frequency. Concrete specimens (160 mm diameter and 320 mm height) are fabricated with concrete of seven different mixtures (various W/C and S/S + G ratios), which gave porosities varying between 7% and 16%. Ultrasonic velocities in concrete were measured in longitudinal direction. Finally the results showed the influence of ratio W/C, where the porosity of the concretes of a ratio W/C _0,5 have correctly estimated by ultrasonic velocity. The integration of the concretes of a lower ratio, in this relation, caused a great dispersion. Porosity estimation of concretes with a ratio W/C lower than 0,5 became specific to each ratio.

  13. 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.

  14. Reinforced concrete tomography

    International Nuclear Information System (INIS)

    In this paper we describe the technique of reinforced concrete tomography, its historical background, recent technological developments and main applications. Gamma radiation sensitive plates are imprinted with radiation going through the concrete sample under study, and then processed to reveal the presence of reinforcement and defects in the material density. The three dimensional reconstruction, or tomography, of the reinforcement out of a single gammagraphy is an original development alternative to conventional methods. Re-bar diameters and positions may be determined with an accuracy of ± 1 mm 0.5-1 cm, respectively. The non-destructive character of this technique makes it particularly attractive in cases of inhabited buildings and diagnoses of balconies. (author)

  15. The Albedo of Pervious Cement Concrete Linearly Decreases with Porosity

    OpenAIRE

    Rui Zhang; Guosheng Jiang; Jia Liang

    2015-01-01

    Pervious pavements have been advocated as a potential countermeasure to the urban heat island effect. To understand if pervious pavements stay cooler than conventional pavements, the albedo of the pervious concrete must be understood. This study measured the albedo of pervious concrete with different porosity. Four Portland cement concrete mixes were casted, using designed amounts of sand to vary the porosity of the pervious concrete samples. The samples were sliced and the spectral reflectan...

  16. Concrete and reinforced concrete - glance at future

    OpenAIRE

    Tamrazyan Ashot Georgievich

    2014-01-01

    In the article the information on the upcoming international conference on concrete and reinforced concrete is offered. The aim of the conference is stated, as well as the main points of the program, composition of the conference, the papers’ subject is disclosed. The author highlights the effect of reinforced concrete invention on the world civilization development. According to the author’s point of view, today reinforced concrete became one of the most evident means of the world developmen...

  17. The Future Concrete: Self-Compacting Concrete

    OpenAIRE

    Liana Iureş; Corneliu Bob

    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.

  18. Concrete durability

    Directory of Open Access Journals (Sweden)

    Gaspar Tébar, Demetrio

    1991-03-01

    Full Text Available The evidence that the concrete is not a material for ever was noticed from the beginning of its industrial use. In the present work, the author describes the studies carried out during the last century and the early ages of the present one, mainly devoted to the study of the durability in sea water. At the present days, and in spite of the numerous papers published from then, the study of the concrete durability continues focusing the research priorities and economical resources of researchers and industries related with this material. Moreover, the new laboratory techniques are allowing to understand old problems and even to open again the discussion on reaction mechanisms which were believed to be completely understood. The article finalizes with a brief description of the numerous studies carried out at the Institute Eduardo Torroja on concrete durability, mainly those related with the resistance against gypsum attack (so abundant in our country land and against sea water attack.

    La realidad de que el hormigón no es un material eterno y es susceptible de sufrir ataques por agentes químicos, fue constatada desde el comienzo mismo de su uso industrial. En el presente trabajo el autor enumera los estudios realizados el siglo pasado y a comienzos del presente sobre la durabilidad del hormigón en agua de mar. En la actualidad y a pesar de los numerosos trabajos desarrollados desde entonces, el estudio de la durabilidad del hormigón sigue centrando la atención prioritaria y los recursos económicos de los investigadores e industrias relacionadas con este material. Además las nuevas técnicas de estudio están permitiendo comprender antiguos problemas e incluso reabrir la discusión sobre mecanismos de reacción que se creían completamente explicados. Finaliza el artículo con una descripción somera de los múltiples trabajos realizados en el Instituto Eduardo Torreja sobre la materia, en especial los estudios realizados sobre

  19. Concrete waterproofing in nuclear industry.

    Science.gov (United States)

    Scherbyna, Alexander N; Urusov, Sergei V

    2005-01-01

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

  20. Quality evaluation of aged concrete by ultrasound

    Science.gov (United States)

    Tavossi, H. M.; Tittmann, Bernhard R.; Cohen-Tenoudji, Frederic

    1999-02-01

    The velocity, attenuation and scattering of ultrasonic waves measured in concrete, mortar and cement structures can be used to evaluate their quality with weathering and aging. In this investigation the hardening of concrete mixture with time is monitored by ultrasonic waves under different conditions of temperature and water to cement ratio. The measured ultrasonic parameters can then be utilized to determine the final quality of the completely cured concrete structure from initial measurement. The quality of a concrete structure is determined by its resistance to compression and its rigidity, which should be within the acceptable values required by the design specifications. The internal and external flaws that could lower its strength can also be detected by ultrasonic technique. Aging process of concrete by weathering can be simulated in the laboratory by subjecting the concrete to extremes of cold and hot cycles in the range of temperatures normally encountered in summer and winter. In this research ultrasonic sensors in low frequency range of 40 to 100 kHz are used to monitor the quality of concrete. Ultrasonic pulses transmitted through the concrete sample are recorded for analysis in time and frequency domains. ULtrasonic waves penetration in concrete of the order of few feet has been achieved in laboratory. Data analyses on ultrasonic signal velocity, spectral content, phase and attenuation, can be utilized to evaluate, in situ, the quality and mechanical strength of concrete.

  1. STRUCTURAL AND THERMOPHYSICAL PROPERTIES OF HARDENING CONCRETE

    Directory of Open Access Journals (Sweden)

    L. Krasulina

    2012-01-01

    Full Text Available Structural and thermophysical properties of thermally treated concrete have been studied in the paper. The paper demonstrates regularities of changes in structural and thermophysical properties of concrete during heat treatment process. It is established that stabilization of coefficient values for heat- and temperature conductivity of concrete corresponds to completion of the process pertaining to intensive formation of the material pore structure and indicates the possibility of transition from the stage of isothermal extraction to the stage of temperature decrease. The obtained results are confirmed by studies of strength growth kinetics of concrete samples.

  2. PULSED LASER ABLATION OF CEMENT AND CONCRETE

    Science.gov (United States)

    Laser ablation was investigated as a means of removing radioactive contaminants from the surface and near-surface regions of concrete from nuclear facilities. We present the results of ablation tests on cement and concrete samples using a pulsed Nd:YAG laser with fiber optic beam...

  3. Rapid Drying Concrete

    OpenAIRE

    ECT Team, Purdue

    2015-01-01

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

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

    OpenAIRE

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

    2013-01-01

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

  5. Structure and properties of textile reinforced concrete

    OpenAIRE

    Volkova, A.A.; A.V. Paykov; O.N. Stolyarov; S.G. Semenov; B.E. Melnikov

    2015-01-01

    In this paper the structure and properties of textile-reinforced concrete were investigated. Two types of high strength reinforcing fabrics made of glass and carbon rovings were used in this study. The samples of textile-reinforced concrete were produced. The mechanical properties of the developed samples were determined via a three-point bending test. The maximum flexural strength and reinforcement efficiency were calculated. It was found that the samples with textile reinforcement have high...

  6. 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.

  7. The Influence of Crushed Concrete Demolition Waste Aggregates on the Hardening Process of Concrete Mixtures

    Directory of Open Access Journals (Sweden)

    Olga FINOŽENOK

    2013-03-01

    Full Text Available Concrete – complex structure composite material consisting of the components with various structure and size. Not only coarse and fine aggregates are used in concrete production, but also filler aggregates. Aggregates of natural, man-made origin or aggregates, produced from recycled materials, can be utilised in concrete production. Aggregates can be produced from recycled materials by reprocessing of concrete and reinforced concrete waste. The influence of the filler aggregates produced from the crushed concrete waste on the characteristics of binder’s paste, when part of the binder (5; 10; 15; 20; 25; 30 % is replaced by such filler aggregate, is analysed in the research. Concrete mixtures with natural aggregates and crushed concrete waste were selected and concrete mixtures of required consistence were produced during the research. Exothermic reactions take place during the hardening of concrete mixture, at that time the heat is dissipated, which increases the temperature of the concrete sample. Thus the exothermic processes were investigated during the concrete’s mixture hardening period and the temperatures of exothermic reactions were determined.DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3833

  8. Mobile concrete factory profiability analysis

    OpenAIRE

    Bajželj, Grega

    2009-01-01

    Diploma task deals with the preparation of concrete in the mobile and stationary concrete factory, transport of concrete and the comparison between the cost of preparation of concrete in the mobile and stationary concrete factory. Represented is the way of preparation of concrete in the mobile and stationary concrete factory. I conducted an analysis of the viability of mobile concrete factory, based on a comparison of the cost of preparation of concrete in the mobile and the cost of preparing...

  9. Predicting the Durability of Concrete Structures, including Sulfate Corrosion of Concrete

    OpenAIRE

    V.P. Selyaev; V.A. Neverov; P.V. Selyaev; E.V. Sorokin; O.A. Yudina

    2014-01-01

    Multiple data on the examination of concrete structures indicate that under the influence of various factors (temperature, humidity, gaseous medium) carrying capacity and rigidity during operation are reduced. The problems of assessing the residual life and durability of concrete structures are considered in the article. Experimental studies on the interaction of the concrete samples with aggressive sulfate medium are conducted. By measuring the micro-hardness, isochrones of degradations,...

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

    OpenAIRE

    Férriz Papí, J. A.

    2014-01-01

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

  11. Porosity of the recycled concrete with substitution of recycled concrete aggregate. An experimental study

    OpenAIRE

    Gómez Soberón, José Manuel Vicente

    2002-01-01

    In this paper, we present the experimental analysis of samples of recycled concrete (RC) with replacement of natural aggregate (NA) by recycled aggregate originating from concrete (RCA). The results of the tests of mechanical properties of RC were used for comparison with tests of mercury intrusion porosimetry (MIP), in which the distribution of the theoretical pore radius, critical pore ratio, the surface area of the concrete, threshold ratio and average pore radius were studied at ages of 7...

  12. Innovative process routes for a high-quality concrete recycling.

    Science.gov (United States)

    Menard, Y; Bru, K; Touze, S; Lemoign, A; Poirier, J E; Ruffie, G; Bonnaudin, F; Von Der Weid, F

    2013-06-01

    This study presents alternative methods for the processing of concrete waste. The mechanical stresses needed for the embrittlement of the mortar matrix and further selective crushing of concrete were generated by either electric impulses or microwaves heating. Tests were carried out on lab-made concrete samples representative of concrete waste from concrete mixer trucks and on concrete waste collected on a French demolition site. The results obtained so far show that both techniques can be used to weaken concrete samples and to enhance aggregate selective liberation (that is the production of cement paste-free aggregates) during crushing and grinding. Electric pulses treatment seems to appear more efficient, more robust and less energy consuming (1-3 kWh t(-1)) than microwave treatment (10-40 kWh t(-1)) but it can only be applied on samples in water leading to a major drawback for recycling aggregates or cement paste in the cement production process. PMID:23490359

  13. Flexural Behavior of Textile-Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Volkova Anna

    2016-01-01

    Full Text Available This paper deals with the flexural behaviour of textile-reinforced concrete (TRC. Two samples of TRC made of high strength reinforcing fabrics made of glass and carbon rovings were produced. Three-point bending test was carried out to examine the flexural performance of the developed samples. The maximum flexural strength and reinforcement efficiency were calculated. Experimental results showed that that all types of applied fabric reinforcement contributed to increases strength as compared to nonreinforced concrete. Furthermore, the deformation behavior of reinforced concrete was analyzed. The advantage is in higher residual load-bearing capacity, which allows maintaining the integrity of the structure.

  14. 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.

  15. Neutron activation measurements in research reactor concrete shield

    International Nuclear Information System (INIS)

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

  16. Designing concrete for durability

    OpenAIRE

    Boyd, A.J.; Mindess, S.; Skalny, J.

    2001-01-01

    Some of the factors affecting the durability of modern concrete structures are discussed, with an emphasis on the problems caused by modern portland cements. This is followed by a description of some concrete durability issues of current interest, such as plastic shrinkage, seawater attack, and sulfate attack. The strategies for testing for durability are also discussed. It is concluded that, to produce durable concretes, a holistic approach to concrete construction must be adopted.
    ...

  17. Electrical Resistance Tomography imaging of concrete

    KAUST Repository

    Karhunen, Kimmo

    2010-01-01

    We apply Electrical Resistance Tomography (ERT) for three dimensional imaging of concrete. In ERT, alternating currents are injected into the target using an array of electrodes attached to the target surface, and the resulting voltages are measured using the same electrodes. These boundary measurements are used for reconstructing the internal (3D) conductivity distribution of the target. In reinforced concrete, the metallic phases (reinforcing bars and fibers), cracks and air voids, moisture gradients, and the chloride distribution in the matrix carry contrast with respect to conductivity. While electrical measurements have been widely used to characterize the properties of concrete, only preliminary results of applying ERT to concrete imaging have been published so far. The aim of this paper is to carry out a feasibility evaluation with specifically cast samples. The results indicate that ERT may be a feasible modality for non-destructive evaluation of concrete. © 2009 Elsevier Ltd. All rights reserved.

  18. 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...

  19. 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.

  20. Structure and properties of textile reinforced concrete

    Directory of Open Access Journals (Sweden)

    A.A. Volkova

    2015-11-01

    Full Text Available In this paper the structure and properties of textile-reinforced concrete were investigated. Two types of high strength reinforcing fabrics made of glass and carbon rovings were used in this study. The samples of textile-reinforced concrete were produced. The mechanical properties of the developed samples were determined via a three-point bending test. The maximum flexural strength and reinforcement efficiency were calculated. It was found that the samples with textile reinforcement have higher strength characteristics as compared to nonreinforced concrete. Furthermore, the deformation behavior of reinforced concrete was analyzed. The advantage is in higher residual load-bearing capacity, which allows maintaining the integrity of the structure.

  1. Gamma radiation shielding analysis of lead-flyash concretes

    International Nuclear Information System (INIS)

    Six samples of lead-flyash concrete were prepared with lead as an admixture and by varying flyash content – 0%, 20%, 30%, 40%, 50% and 60% (by weight) by replacing cement and keeping constant w/c ratio. Different gamma radiation interaction parameters used for radiation shielding design were computed theoretically and measured experimentally at 662 keV, 1173 keV and 1332 keV gamma radiation energy using narrow transmission geometry. The obtained results were compared with ordinary-flyash concretes. The radiation exposure rate of gamma radiation sources used was determined with and without lead-flyash concretes. - Highlights: • Concrete samples with lead as admixture were casted with flyash replacing 0%, 20%, 30%, 40%, 50% and 60% of cement content (by weight). • Gamma radiation shielding parameters of concretes for different gamma ray sources were measured. • The attenuation results of lead-flyash concretes were compared with the results of ordinary flyash concretes

  2. 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...

  3. 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...

  4. Behavior of compacted clay-concrete interface

    Institute of Scientific and Technical Information of China (English)

    R.R. SHAKIR; Jungao ZHU

    2009-01-01

    Tests of interface between compacted clay and concrete were conducted systematically using interface simple shear test apparatus. The samples, having same dry density with different water content ratio, were prepared.Two types of concrete with different surface roughness, i.e., relatively smooth and relatively rough surface rough-ness, were also prepared. The main objectives of this paper are to show the effect of water content, normal stress and rough surface on the shear stress-shear displacement relationship of clay-concrete interface. The following were concluded in this study: 1) the interface shear sliding dominates the interface shear displacement behavior for both cases of relatively rough and smooth concrete surface except when the clay water content is greater than 16% for the case of rough concrete surface where the shear failure occurs in the body of the clay sample; 2) the results of interface shear strength obtained by direct shear test were different from that of simple shear test for the case of rough concrete surface; 3) two types of interface failure mechanism may change each other with different water content ratio; 4) the interface shear strength increases with increasing water content ratio especially for the case of clay-rough concrete surface interface.

  5. Performance of Recycled Aggregate Concrete Containing Micronised Biomass Silica

    OpenAIRE

    Suraya Hani Adnan; Ismail Abdul Rahman; Lee Yee Loon

    2011-01-01

    This paper presents a study on Micronised Biomass Silica (MBS) that was produced from the controlled burning of waste Rice Husk. The MBS was used as pozzolan material to enhance the performance of Recycled Aggregate Concrete (RAC). Various percentages by mass of Micronised Biomass Silica were applied in the normal and recycled aggregate concrete cube samples. Compressive strength and water permeability tested on the samples at the age of 7, 14, 28 and 90 days showed that concrete containing M...

  6. Impact resistance of concrete – using slit rubber from tyres

    OpenAIRE

    Coventry, Kathryn; Richardson, Alan; Diaz, Eli

    2015-01-01

    This paper examines recycled tyre rubber, which was machine cut into slits and these were added to Portland cement concrete mixes in different percentages, based on specimen volume. They were then tested to determine the impact performance of each mix in comparison to a plain non-rubberised mix. The results indicated that concrete samples containing recycled rubber, exhibited a loss in compressive strength when compared to the plain concrete mix, however, the rubber modified samples w...

  7. Transient heating effect on high strength concrete

    International Nuclear Information System (INIS)

    This study shows some differences in the properties and the behaviour at high temperature of two concretes (ordinary and high strength) made with the same calcareous aggregates. During heating tests at 1 C min-1, cylindrical samples of diameter 160 x 320 mm of high strength concrete, more dense, may explode in a critical temperature zone between 250 and 300 C. Differences in behaviour between OC and HSC appeared at high temperatures: there were disparities especially in thermo-hydric transfer, porosity and thermal stability. The dense microstructure of high strength concrete was found to slow up the escape of vaporized water. (orig.)

  8. Compressive Strength of Fiber Reinforced Fly- Ash Concrete using Regression Model

    OpenAIRE

    H.S. Chore; P.A. Dode; N.L. Shelke

    2011-01-01

    In construction industry, strength is a primary criterion in selecting a concrete for a particular application. Concrete used for construction gains strength over a long period of time after pouring the concrete. The characteristic strength of concrete is defined as the compressive strength of a sample that has been aged for 28 days. Neither waiting 28 days for such a test would not serve the rapidity of construction, nor would neglecting it serve the quality control process on concrete in la...

  9. Influence of self-compacting concrete composition on sulfuric acid attack

    OpenAIRE

    Feys, Dimitri; Liu, Zanqun; Heirman, Gert; De Schutter, Geert; Boel, Veerle; Desmet, Bram; Vantomme, John; Cizer, Özlem; Vandewalle, Lucie; Gemert, Dionys van

    2009-01-01

    Sulfuric acid attack on concrete has been reported for over a century. Many scientific papers deal with the issue of concrete damage due to sulfate and sulfuric attack. The introduction of self-compacting concrete introduces new questions related to the behaviour of powder-rich mixtures in a sulfate environment. This paper describes a simple testing method to investigate the influence of the concrete composition on the sulfuric acid attack. Concrete samples have been submerged in a sulfate...

  10. Special protective concretes

    International Nuclear Information System (INIS)

    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.)

  11. 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.

  12. Low Temperature Concrete Admixture

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Performing construction processes under the cold weather condition requires construction engineers to plan operations considering low temperature condition. Concrete admixture mostly chemically interact with the constituents of concrete and affect the properties and characteristics of the fresh and hardened concrete and its durability. The purposes of the admixtures include water reduction, high strength, corrosion protection, crack control, finish enhancement, flowability, etc. One of the in...

  13. Concrete bridge prioritization system

    OpenAIRE

    Kesselring, Debbie Anne

    1995-01-01

    An alternative method of prioritization for concrete bridge maintenance, repair, and rehabilitation activities is required due to the inability of the current system to manage the increasing nmnber of aging concrete bridges. The Concrete Bridge Prioritization System was proposed because of its ability to address the critical technical parameters of safety and cost benefit in prioritization of funding and work allocation. The analysis includes four parts, service life assessment, s...

  14. Sustainable Concrete Technology

    OpenAIRE

    Sim J.; Lee K.H.

    2015-01-01

    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 ...

  15. Developing arithmetic deformation model of complex reiforced concrete plate with polymer concrete layer under the impact of corrosive medium

    Directory of Open Access Journals (Sweden)

    Treshchev Aleksandr Anatol'evich

    2014-03-01

    Full Text Available The arithmetic model of reinforced concrete slab distortion with a polymer-concrete layer exposed to aggressive influences is introduced. The relevance of this object choice as a matter of actual practice. The least contradictory model for specification of the strain-stress state of reinforced concrete constructions is sampled. The most efficient way of solving such tasks is the finite elements method, which lacks the drawbacks of the finite differences method. In this article, the arithmetic model of hybrid finite element qualification for the armored reinforced concrete slabs design is considered. The problem of reinforced concrete slab with a polymer-concrete layer bending is dealt with in the presence of dynamic deformation and simple loading, which gives the opportunity to introduce concrete as a nonlinear material with its elastic-plastic properties, which stay within the strain potential limits. The deformation of creep is not taken into account. The incremental equations connecting stress and deformation increments are provided.

  16. Predicting the Durability of Concrete Structures, including Sulfate Corrosion of Concrete

    Directory of Open Access Journals (Sweden)

    V.P. Selyaev

    2014-02-01

    Full Text Available Multiple data on the examination of concrete structures indicate that under the influence of various factors (temperature, humidity, gaseous medium carrying capacity and rigidity during operation are reduced. The problems of assessing the residual life and durability of concrete structures are considered in the article. Experimental studies on the interaction of the concrete samples with aggressive sulfate medium are conducted. By measuring the micro-hardness, isochrones of degradations, enabling experiments to determine the rate of advance of the destruction front deep into the product; intensity changes in the durability properties of the material surface and other features which characterize the degradation process were obtained. The article investigates the mechanisms of corrosion processes in reinforced concrete in condition of sulfate corrosion. The paper proposes the calculation model and the method that predict the durability of concrete structures.

  17. Effects of Water Jet on Heat-Affected Concretes

    OpenAIRE

    Sitek, L. (Libor); Bodnárová, L.; Válek, J. (Jan); M. Zeleňák; Klich, J. (Jiří); Foldyna, J.; Novotný, M.

    2013-01-01

    The paper is dealing with the effects of flat high-speed water jet on concretes affected by high temperature. Research should help to correct use of water jet technology in repair works on concrete structures especially after wildfires in tunnels, underground garages, etc., which are exposed to enormous thermal stress. Four concrete mixtures were prepared for tests of interaction of water jet with concrete. The samples were exposed to 200 °C and 600 °C and for comparison one third of samples ...

  18. Concrete fracture models and applications

    CERN Document Server

    Kumar, Shailendra

    2011-01-01

    Concrete-Fracture Models and Applications provides a basic introduction to nonlinear concrete fracture models. Readers will find a state-of-the-art review on various aspects of the material behavior and development of different concrete fracture models.

  19. Organic compounds in concrete from demolition works.

    Science.gov (United States)

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

    2015-11-01

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

  20. Environmental Impact of Concrete

    Directory of Open Access Journals (Sweden)

    Dan Babor

    2009-01-01

    Full Text Available The cement and concrete industries are huge. What does this mean in terms of the environment? Concrete and other cementitious materials have both environmental advantages and disadvantages. This paper takes a look at how these materials are made, then reviews a number of environmental considerations relating to their production and use.

  1. Service life of concrete

    International Nuclear Information System (INIS)

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

  2. concrete5 Beginner's Guide

    CERN Document Server

    Laubacher, Remo

    2011-01-01

    This book is part of Packt's Beginner's Guide series. You will be guided through the set up of a Concrete5 site with step-by-step practical examples. This book is ideal for developers who would like to build their first site with Concrete5. Some k

  3. Environmental Impact of Concrete

    OpenAIRE

    Dan Babor; Diana Plian; Loredana Judele

    2009-01-01

    The cement and concrete industries are huge. What does this mean in terms of the environment? Concrete and other cementitious materials have both environmental advantages and disadvantages. This paper takes a look at how these materials are made, then reviews a number of environmental considerations relating to their production and use.

  4. 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.

  5. Sodium concrete reactions

    International Nuclear Information System (INIS)

    The data from an extensive series of sodium/concrete reaction tests are presented and mechanisms by which the reactions proceed are analyzed. The results indicate water transport and the resulting sodium/water reaction dominate both the chemical energy release and H2 generation. A mechanism which explains the limited penetration of concrete observed in most of these tests is proposed

  6. 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..

  7. Electrokinetic decontamination of concrete

    International Nuclear Information System (INIS)

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

  8. Expansion of Hanford concrete

    International Nuclear Information System (INIS)

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

  9. Production of an economic high-density concrete for shielding megavoltage radiotherapy rooms and nuclear reactors

    International Nuclear Information System (INIS)

    In megavoltage radiotherapy rooms, ordinary concrete is usually used due to its low construction costs, although higher density concrete are sometimes used, as well. The use of high-density concrete decreases the required thickness of the concrete barrier; hence, its disadvantage is its high cost. In a nuclear reactor, neutron radiation is the most difficult to shield. A method for production of economic high-density concrete witt, appropriate engineering properties would be very useful. Materials and Methods: Galena (Pb S) mineral was used to produce of a high-density concrete. Galena can be found in many parts of Iran. Two types of concrete mixes were produced. The water-to-concrete (w/c) ratios of the reference and galena concrete mixes were 0.53 and 0.25, respectively. To measure the gamma radiation attenuation of Galena concrete samples, they were exposed to a narrow beam of gamma rays emitted from a cobalt-60 therapy unit. Results: The Galena mineral used in this study had a density of 7400 kg/m3. The concrete samples had a density of 4800 kg/m3. The measured half value layer thickness of the Galena concrete samples for cobalt 60 gamma rays was much less than that of ordinary concrete (2.6 cm compared to 6.0 cm). Furthermore, the galena concrete samples had significantly higher compressive strength (500 kg/cm2 compared to 300 kg/cm2). Conclusion: The Galena concrete samples made in our laboratories had showed good shielding/engineering properties in comparison with all samples made by using high-density materials other than depleted uranium. Based on the preliminary results, Galena concrete is maybe a suitable option where high-density concrete is required in megavoltage radiotherapy rooms as well as nuclear reactors

  10. The Albedo of Pervious Cement Concrete Linearly Decreases with Porosity

    Directory of Open Access Journals (Sweden)

    Rui Zhang

    2015-01-01

    Full Text Available Pervious pavements have been advocated as a potential countermeasure to the urban heat island effect. To understand if pervious pavements stay cooler than conventional pavements, the albedo of the pervious concrete must be understood. This study measured the albedo of pervious concrete with different porosity. Four Portland cement concrete mixes were casted, using designed amounts of sand to vary the porosity of the pervious concrete samples. The samples were sliced and the spectral reflectance and albedo of the sliced samples were measured and analyzed. It is found that the albedo of pervious concrete decreases linearly with the increase of the porosity. The albedo of a pervious Portland concrete varies from 0.25 to 0.35, which is 0.05~0.15 lower than the albedo of conventional cement concrete. Due to this lower albedo, it should be cautious to develop pervious concrete to battle with urban heat island unless the evaporation of pervious concrete is promoted to compensate the additional solar absorption caused by the low albedo.

  11. Assessing relationships among properties of demolished concrete, recycled aggregate and recycled aggregate concrete using regression analysis.

    Science.gov (United States)

    Tam, Vivian W Y; Wang, K; Tam, C M

    2008-04-01

    Recycled demolished concrete (DC) as recycled aggregate (RA) and recycled aggregate concrete (RAC) is generally suitable for most construction applications. Low-grade applications, including sub-base and roadwork, have been implemented in many countries; however, higher-grade activities are rarely considered. This paper examines relationships among DC characteristics, properties of their RA and strength of their RAC using regression analysis. Ten samples collected from demolition sites are examined. The results show strong correlation among the DC samples, properties of RA and RAC. It should be highlighted that inferior quality of DC will lower the quality of RA and thus their RAC. Prediction of RAC strength is also formulated from the DC characteristics and the RA properties. From that, the RAC performance from DC and RA can be estimated. In addition, RAC design requirements can also be developed at the initial stage of concrete demolition. Recommendations are also given to improve the future concreting practice. PMID:17764837

  12. Activation of TRIGA Mark II research reactor concrete shield

    International Nuclear Information System (INIS)

    To determine neutron activation inside the TRIGA research reactor concrete body a special sample-holder for irradiation inside horizontal channel was developed and tested. In the sample-holder various samples can be irradiated at different concrete shielding depths. In this paper the description of the sample-holder, experiment conditions and results of long-lived activation measurements are given. Long-lived neutron-induced gamma-ray-emitting radioactive nuclides in the samples were measured with HPGe detector. The most active long-lived radioactive nuclides in ordinary concrete samples were found to be 60Co and 152Eu and in barytes concrete samples 60Co, 152Eu and 133Ba. Measured activity density of all nuclides was found to decrease almost linearly with depth in logarithmic scale. (author)

  13. Concrete Infrastructure Corrosion

    International Nuclear Information System (INIS)

    It is well known that many reinforced concrete structures are at risk of deterioration due to chloride ion contamination of the concrete or atmospheric carbon dioxide dissolving in water to form carbonic acid, which reacts with the concrete and the reinforcing steel. The environment within the concrete will determine the corrosion product layers, which might, inter alia, contain the oxides and/or hydroxides of iron. Tensile forces resulting from volume changes during their formation lead to the cracking and delamination of the concrete. In the present investigation the handrail of an outside staircase suffered rebar corrosion during 30 year's service, leading to severe delamination damage to the concrete structure. The railings had been sealed into the concrete staircase using a polysulphide sealant, Thiokol. The corrosion products were identified by means of Moessbauer and SEM analyses, which indicated that the corrosion product composition varied from the original steel surface to the outer layers, the former being mainly iron oxides and the latter iron oxyhydroxide.

  14. Behaviour of Recycled Coarse Aggregate Concrete: Age and Successive Recycling

    Science.gov (United States)

    Sahoo, Kirtikanta; Pathappilly, Robin Davis; Sarkar, Pradip

    2016-06-01

    Recycled Coarse Aggregate (RCA) concrete construction technique can be called as `green concrete', as it minimizes the environmental hazard of the concrete waste disposal. Indian standard recommends target mean compressive strength of the conventional concrete in terms of water cement ratio ( w/ c). The present work is an attempt to study the behaviour of RCA concrete from two samples of parent concrete having different age group with regard to the relationship of compressive strength with water cement ratios. Number of recycling may influence the mechanical properties of RCA concrete. The influence of age and successive recycling on the properties such as capillary water absorption, drying shrinkage strain, air content, flexural strength and tensile splitting strength of the RCA concrete are examined. The relationship between compressive strength at different w/ c ratios obtained experimentally is investigated for the two parameters such as age of parent concrete and successive recycling. The recycled concrete using older recycled aggregate shows poor quality. While the compressive strength reduces with successive recycling gradually, the capillary water absorption increases abruptly, which leads to the conclusion that further recycling may not be advisable.

  15. Development of ultrasonic methods for the nondestructive inspection of concrete

    Science.gov (United States)

    Claytor, T. M.; Ellingson, W. A.

    1983-08-01

    Nondestructive inspection of Portland cement and refractory concrete is conducted to determine strength, thickness, presence of voids or foreign matter, presence of cracks, amount of degradation due to chemical attack, and other properties without the necessity of coring the structure (which is usually accomplished by destructively removing a sample). The state of the art of acoustic nondestructive testing methods for Portland cement and refractory concrete is reviewed. Most nondestructive work on concrete has concentrated on measuring acoustic velocity by through transmission methods. Development of a reliable pitch-catch or pulse-echo system would provide a method of measuring thickness with access from only one side of the concrete.

  16. Internal deterioration of concrete by the oxidation of pyrrhotitic aggregates

    International Nuclear Information System (INIS)

    This paper presents research results on the causes of a severe concrete deterioration, which occurred in many building foundations approximately 2 years after construction. Concrete samples were investigated with X-ray diffraction (XRD) analysis, a scanning electron microscope (SEM) and a petrographic examination performed with a stereomicroscope. It was found that the early cracking of concrete stemmed from the oxidation of the pyrrhotite found in the anorthosite aggregates used to produce the concrete. The oxidation process led to the precipitation of iron hydroxides having a higher volume than the original pyrrhotite does. The presence of micas (biotite) close to the pyrrhotite seemed to promote and accelerate the oxidation process

  17. Performance Enhancement of the Automated Concrete Evaluation System (ACES)

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-02-14

    The objective of this proposed research is to improve and expand the detection and analysis capabilities of the automated, concrete evaluation (ACE) system. MoDOT and Honeywell jointly developed this system. The focus of this proposed research will be on the following: Coordination of concrete imaging efforts with other states, Validation and testing of the ACE system on a broad range of concrete samples, and Identification and development of software and hardware enhancements. These enhancements will meet the needs of diverse users in the field of concrete materials, construction, and research.

  18. Performance Enhancement of the Automated Concrete Evaluation System (ACES)

    International Nuclear Information System (INIS)

    The objective of this proposed research is to improve and expand the detection and analysis capabilities of the automated, concrete evaluation (ACE) system. MoDOT and Honeywell jointly developed this system. The focus of this proposed research will be on the following: Coordination of concrete imaging efforts with other states, Validation and testing of the ACE system on a broad range of concrete samples, and Identification and development of software and hardware enhancements. These enhancements will meet the needs of diverse users in the field of concrete materials, construction, and research

  19. 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.

  20. Injection technologies for the repair of damaged concrete structures

    CERN Document Server

    Panasyuk, V V; Sylovanyuk, V P

    2014-01-01

    This book analyzes the most important achievements in science and engineering practice concerning operational factors that cause damage to concrete and reinforced concrete structures. It includes methods for assessing their strength and service life, especially those that are based on modern concepts of the fracture mechanics of materials. It also includes basic approaches to the prediction of the remaining service life for long-term operational structures. Much attention is paid to injection technologies for restoring the serviceability of damaged concrete and reinforced concrete structures. In particular, technologies for remedying holes, cracks, corrosion damages etc. The books contains sample cases in which the above technologies have been used to restore structural integrity and extend the reliable service life of concrete and reinforced concrete constructions, especially NPPs, underground railways, bridges, seaports and historical relics.

  1. DESIGN OF ULTRA-LIGHTWEIGHT CONCRETE: TOWARDS MONOLITHIC CONCRETE STRUCTURES

    OpenAIRE

    Yu Qing Liang; Spiesz Przemek; Brouwers Jos

    2014-01-01

    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 m...

  2. 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.

  3. Radon emanation fractions from concretes containing fly ash and metakaolin

    International Nuclear Information System (INIS)

    Radon (222Rn) and progenies emanate from soil and building components and can create an indoor air quality hazard. In this study, nine concrete constituents, including the supplementary cementitious materials (SCMs) fly ash and metakaolin, were used to create eleven different concrete mixtures. We investigated the effect of constituent radium specific activity, radon effective activity and emanation fraction on the concrete emanation fraction and the radon exhalation rate. Given the serious health effects associated with radionuclide exposure, experimental results were coupled with Monte Carlo simulations to demonstrate predictive differences in the indoor radon concentration due to concrete mixture design. The results from this study show that, on average, fly ash constituents possessed radium specific activities ranging from 100 Bq/kg to 200 Bq/kg and emanation fractions ranging from 1.1% to 2.5%. The lowest emitting concrete mixture containing fly ash resulted in a 3.4% reduction in the concrete emanation fraction, owing to the relatively low emanation that exists when fly ash is part of concrete. On average, the metakaolin constituents contained radium specific activities ranging from 67 Bq/kg to 600 Bq/kg and emanation fractions ranging from 8.4% to 15.5%, and changed the total concrete emanation fraction by roughly ± 5% relative to control samples. The results from this study suggest that SCMs can reduce indoor radon exposure from concrete, contingent upon SCM radionucleotide content and emanation fraction. Lastly, the experimental results provide SCM-specific concrete emanation fractions for indoor radon exposure modeling. - Highlights: • Fly ash or metakaolin SCMs can neutralize or reduce concrete emanation fractions. • The specific activity of constituents is a poor predictor of the concrete emanation fraction. • Exhalation from fly ash concretes represents a small fraction of the total indoor radon concentration

  4. Deterioration of PCPV concrete

    International Nuclear Information System (INIS)

    This paper presents results obtained from an experimental investigation into the deterioration of concretes used in prestressed concrete pressure vessels (PCPVs) in the UK. The experimental works were focused on the dependence of the residual properties of the thermally loaded concretes on the mix design (3 representative PCPVs), levels of exposed temperature (from 20 to 450 C), test age (3 months and 1 year) and exposure condition (sealed and unsealed). The residual properties investigated in this project were conducted by fully using both destructive (compressive, tensile splitting and static modulus) and non-destructive (dynamic modulus and ultrasonic pulse velocity) test techniques with the aim of better understanding and characterising the deterioration of PCPV concretes when subjected to both ambient and elevated temperatures under the environmental conditions likely to be experienced in real structures. Detailed statistical analyses and discussions on the experimental results were also performed and presented. (orig.)

  5. Concrete decontamination scoping tests

    International Nuclear Information System (INIS)

    This report details the research efforts and scoping tests performed at the Idaho Chemical Process Plant using scabbling, chemical, and electro-osmotic decontamination techniques on radiologically contaminated concrete

  6. 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...

  7. ADVANCEMENTS IN CONCRETE TECHNOLOGY

    OpenAIRE

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

    2015-01-01

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

  8. High performance polymer concrete

    OpenAIRE

    Frías, M.; San-José, J. T.

    2007-01-01

    This paper studies the performance of concrete whose chief components are natural aggregate and an organic binder —a thermosetting polyester resin— denominated polymer concrete or PC. The material was examined macro- and microscopically and its basic physical and mechanical properties were determined using mercury porosimetry, scanning electron microscopy (SEM-EDAX), X-ray diffraction (XRD) and strength tests (modulus of elasticity, stress-strain curves and ultimate strengths). A...

  9. Corrosion inhibition in self-compacting concrete

    OpenAIRE

    Blankson, Marva Angela

    2013-01-01

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

  10. Performance of "Waterless Concrete"

    Science.gov (United States)

    Toutanji, H. A.; Grugel, R. N.

    2009-01-01

    Waterless concrete consists of molten elementary sulfur and aggregate. The aggregates in a lunar environment will be lunar rocks and soil. Sulfur is present on the Moon in Troilite soil (FeS) and, by oxidation of the soil, iron and sulfur can be produced. Sulfur concrete specimens were cycled between liquid nitrogen (approx.]91 C) and room temperature (^21 C) to simulate exposure to a lunar environment. Cycled and control specimens were subsequently tested in compression at room temperatures (^21 C) and ^-101 C. Test results showed that due to temperature cycling, the compressive strength of cycled specimens was 20% of those non-cycled. This reduction in strength can be attributed to the large differences in thermal coefficients of expansion of the materials constituting the concrete which promoted cracking. Similar sulfur concrete mixtures were strengthened with short and long glass fibres. The lunar regolith simulant was melted in a 25 cc Pt- Rh crucible in a Sybron Thermoline high temperature MoSi2 furnace at melting temperatures of 1450 to 1600 C for times of 30 min to i hour. Glass fibres and small rods were pulled from the melt. The glass fibres were used to reinforce sulfur concrete plated to improve the flexural strength of the sulfur concrete. Beams strengthened with glass fibres showed to exhibit an increase in the flexural strength by as much as 45%.

  11. Separation of contaminated concrete

    International Nuclear Information System (INIS)

    Separating the contaminated parts from the non-contaminated parts from decommissioned nuclear facilities may strongly reduce the amount of contaminated concrete. The reduction in volume of the radioactive contaminated concrete is dependent on how much cementstone is in the concrete. This research program shows that the radioactive contamination is mostly in the cementstone. However the choice that the cementstone parts, (or better said the radioactive parts) are smaller than 1 mm may not always be true. Normally the cementstone takes about 30% of the total concrete volume. A separation procedure composed by a combination of milling and thermal shock has been assessed. Both the cold and hot thermal shock in combination with milling are not able to separate the cementstone from the larger aggregates completely. However, the cementstone from the concrete with a low nominal grain size seems to be almost completely removed by the combination cold thermal shock/milling, while the cementstone from the concrete with a high nominal grain size seems to be almost completely removed by the combination hot thermal shock/milling. After both methods a layer of cementstone was still visible on the aggregates. Washing followed by a nitric acid treatment removed each 2 wt% of cementstone

  12. Translating concrete poetry Translating concrete poetry

    Directory of Open Access Journals (Sweden)

    Kirsten Malmkjaer

    2008-04-01

    Full Text Available It is interesting to examine the art form known as concrete poetry with translation -- both practical and theoretical -- in mind, because it was, according to Kopfermann (1974:x1, considered international by its creators: the language-elements are not tied to the author's mother tongue, reduction and reproduction allow elements of different languages to be combined in the scone text. The basis for this is the materiality (mostly understood in an optical or acoustic sense of the vocable° and elementary structures which are the sane in all (or at least the Indo- -European languages. This theoretical stance might suggest that it is not necessary to translate concrete poetry from one Indo-European language to another. However, most anthologies of concrete poetry contain translations and/or word glosses (see, for instance, Bann (1967, Solt (1968 and Williams (1967, so there is obviously a perceived need to provide some assistance to speakers of languages other than that in which any particular poem is composed.

  13. Offshore concrete structures

    International Nuclear Information System (INIS)

    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

  14. 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.

  15. Characterization of High Density Concrete by Ultrasonic Goniometer

    International Nuclear Information System (INIS)

    This paper described the results of ultrasonic goniometer measurements on concrete containing hematite. Local hematite stones were used as aggregates to produce high density concrete for application in X-and gamma shielding. Concrete cube samples (150 mm x 150 mm x 150 mm) containing hematite as coarse aggregates were prepared by changing mix ratio, water to cement ratio (w/ c) and types of fine aggregate. All samples were cured in water for 7 days. After 28 days of casting, the concrete cubes were then cut into small size of about 10 mm x 20 mm x 30 mm so that it can be fitted into goniometer specimen holder. From this measurement, longitudinal, shear and surface Rayleigh waves in the concrete can be determined. The measurement results are explained and discussed. (author)

  16. Corrosion of steel reinforced concrete in the tropical coastal atmosphere of Havana City, Cuba

    OpenAIRE

    Abel Castañeda; Juan José Howland; Francisco Corvo; Tezozomoc Pérez

    2013-01-01

    The influence of chloride deposition rate on concrete using an atmospheric corrosion approach is rarely studied in the literature. Seven exposure sites were selected in Havana City, Cuba, for exposure of reinforced concrete samples. Two significantly different atmospheric corrosivity levels with respect to corrosion of steel reinforced concrete were observed after two years of exposure depending on atmospheric chloride deposition and w/c ratio of the concrete. Changes in corrosion current are...

  17. An investigation of tendon sheathing filler migration into concrete

    International Nuclear Information System (INIS)

    During some of the inspections at nuclear power plants with prestressed concrete containments, it was observed that the containments has experienced leakage of the tendon sheathing filler (i.e., streaks). The objective of this activity was to provide an indication of the extent of tendon sheathing filler leakage into the concrete and its affects on concrete properties. Literature was reviewed and concrete core samples were obtained from the Trojan Nuclear Plant and tested. The literature primarily addressed effects of crude or lubricating oils that are known to cause concrete damage. However, these materials have significantly different characteristics relative to the materials used as tendon sheathing fillers. Examination and testing of the concrete cores indicated that the appearance of tendon sheathing filler on the concrete surface was due to leakage from the conduits and its subsequent migration through cracks that were present. Migration of the tendon sheathing filler was confined to the cracks and there was no perceptible movement into the concrete. Results of compressive strength testing indicated that the concrete quality was consistent in the containment and that the strength had increased over 40% in 25.4 years relative to the average compressive strength at 28-days age

  18. Innovation in concrete research-review and perspective

    International Nuclear Information System (INIS)

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

  19. Magnesium oxychloride cement concrete

    Indian Academy of Sciences (India)

    A K Misra; Renu Mathur

    2007-06-01

    The scope of magnesium oxychloride (MOC) cement in concrete works has been evaluated. MOC cement concrete compositions of varying strengths having good placing and finishing characteristics were prepared and investigated for their compressive and flexural strengths, -values, abrasion resistance etc. The durability of MOC concrete compositions against extreme environmental conditions viz. heating–cooling, freezing–thawing, wetting–drying and penetration and deposition of salts etc were investigated. The results reveal that MOC concrete has high compressive strength associated with high flexural strength and the ratio of compressive to flexural strength varies between 6 and 8. The elastic moduli of the compositions studied are found to be 23–85 GPa and the abrasion losses between 0.11 and 0.20%. While alternate heating–cooling cycles have no adverse effect on MOC concrete, it can be made durable against freezing–thawing and the excessive exposure to water and salt attack by replacing 10% magnesium chloride solution by magnesium sulphate solution of the same concentration.

  20. Production of a datolite-based heavy concrete for shielding nuclear reactors and megavoltage radiotherapy rooms

    International Nuclear Information System (INIS)

    Biological shielding of nuclear reactors has always been a great concern and decreasing the complexity and expense of these installations is of great interest. In this study, we used datolite and galena minerals for production of a high performance heavy concrete. Materials and Methods: Datolite and galena minerals which can be found in many parts of Iran were used in the concrete mix design. To measure the gamma radiation attenuation of the Datolite and galena concrete samples, they were exposed to both narrow and wide beams of gamma rays emitted from a cobalt-60 radiotherapy unit. An Am-Be neutron source was used for assessing the shielding properties of the samples against neutrons. To test the compression strengths, both types of concrete mixes (Datolite and galena and ordinary concrete) were investigated. Results: The concrete samples had a density of 4420-4650 kg/m3 compared to that of ordinary concrete (2300-2500 kg/m3) or barite high density concrete (up to 3500 kg/m3). The measured half value layer thickness of the Datolite and galena concrete samples for cobalt-60 gamma rays was much less than that of ordinary concrete (2.56 cm compared to 6.0 cm). Furthermore, the galena concrete samples had a significantly higher compressive strength as well as 20% more neutron absorption. Conclusion: The Datolite and galena concrete samples showed good shielding/engineering properties in comparison with other reported samples made, using high-density materials other than depleted uranium. It is also more economic than the high-density concretes. Datolite and galena concrete may be a suitable option for shielding nuclear reactors and megavoltage radiotherapy rooms.

  1. Evaluation of microbially-influenced degradation of massive concrete structures

    International Nuclear Information System (INIS)

    Many low level waste disposal vaults, both above and below ground, are constructed of concrete. One potential contributing agent to the destruction of concrete structures is microbially-influenced degradation (MID). Three groups of bacteria are known to create conditions that are conducive to destroying concrete integrity. They are sulfur oxidizing bacteria, nitrifying bacteria, and heterotrophic bacteria. Research is being conducted at the Idaho National Engineering Laboratory to assess the extent of naturally occurring microbially influenced degradation (MID) and its contribution to the deterioration of massive concrete structures. The preliminary steps to understanding the extent of MID, require assessing the microbial communities present on degrading concrete surfaces. Ultimately such information can be used to develop guidelines for preventive or corrective treatments for MID and aid in formulation of new materials to resist corrosion. An environmental study was conducted to determine the presence and activity of potential MID bacteria on degrading concrete surfaces of massive concrete structures. Scanning electron microscopy detected bacteria on the surfaces of concrete structures such as bridges and dams, where corrosion was evident. Enumeration of sulfur oxidizing thiobacilli and nitrogen oxidizing Nitrosomonas sp. and Nitrobacter sp. from surface samples was conducted. Bacterial community composition varied between sampling locations, and generally the presence of either sulfur oxidizers or nitrifiers dominated, although instances of both types of bacteria occurring together were encountered. No clear correlation between bacterial numbers and degree of degradation was exhibited

  2. Test of dust scattering caused by dumpling of concrete materials

    International Nuclear Information System (INIS)

    The behaviors of dust at the disposal of low-level radioactive concrete waste were investigated for making an estimation of exposure dose of the workers who inhale a contaminated dust in the air. Dust concentration and it's particle size in the air caused by the dumping test of mock concrete materials were measured. The concrete dusts scatter usually by grinding, cutting, and blasting of a lump of concrete. Three test concrete samples of different sizes, such as particulate (crushed stone), broken concrete (small pieces of about 5 mm - 20 cm), and broken concrete (large pieces of about 30 cm) were used in the dumping test. Concentrations of suspended and respirable dust (< 10 μm) in the air were measured by digital aerosol monitors and dust samplers which were located at 4 - 10 m distant from a dropping center. A testing house was built for avoiding from the effects of environment, such as wind direction and wind velocity. The test samples were dropped on the surface of steel plate from about 1 meter height at a low and a high wind condition. In case of the particulate test sample, the dropping height and the wind velocity affected to the dust concentration in the air. The dust scattering was largely suppressed by the uses of water sprinkling, suppression sheet and wet test sample. (Suetake, M.)

  3. Hydraulic design of pervious concrete highway shoulders

    Science.gov (United States)

    Grahl, Nathan Andrew

    Stormwater drainage has been a factor in roadway design for years. Now stormwater quantity and quality are also becoming regulated for roadways. As regulations of stormwater management continue to increase so does the need for more viable and effect management practices. The research presented and discussed in this thesis presents the option of using pervious concrete in highway shoulders as a best management practice for stormwater management. Research focused on the hydraulic response of pervious concrete pavements exposed to sheet flowing water. Pervious concrete samples were placed in a hydraulic flume to determine capture discharges, infiltration rates, and by-pass flowrates for a broad range of void contents, across a broad range of pavement cross slopes. The results demonstrate that the capture discharge and infiltration rates are inversely related to the cross slope of the pavement. Results also showed the infiltration rate of the permeable pavement exposed to sheet flowing water, in the model, is significantly lower than the measured infiltration rate. Pervious concrete samples were also tested to determine hydraulic response when exposed to clogging associated with sand used in roadway de-icing. The results of the clogging of the permeable pavements followed similar trends as the unclogged samples, with the only difference being a more significant reduction in infiltration rates at higher applications of sand. Preliminary discussion of a design methodology is included with a design example.

  4. HIGH TEMPERATURE PERFORMANCE OF SUSTAINABLE CONCRETE WITH RECYCLED CONCRETE AGGREGATES

    OpenAIRE

    Gales, John; Parker, Thomas; Green, Mark F.; Cree, Duncan; Bisby, Luke

    2014-01-01

    The substitution of conventional aggregates in concrete with recycled concrete aggregates (RCA) can act to lower environmental impact. Applications of concrete with RCA are limited because of a lack of research providing clear design guidance. Specifically, the performance in fire must be considered. To address this need, three different concrete mixes were assessed for performance at high temperature with the only variable being the proportion of coarse aggregate substituted with RCA. For ea...

  5. Water Entrainment in Concrete

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Hansen, Per Freiesleben

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

  6. Concrete characterization for the 300 Area Solvent Evaporator Closure Site

    International Nuclear Information System (INIS)

    This report summarizes the sampling activities undertaken and the analytical results obtained in a concrete sampling and analyses study performed for the 300 Area Solvent Evaporator (300 ASE) closure site. The 300 ASE is identified as a Resource Conservation and Recovery Act (RCRA) treatment, storage, or disposal (TSD) unit that will be closed in accordance with the applicable laws and regulations. No constituents of concern were found in concentrations indicating contamination of the concrete by 300 ASE operations

  7. Flexural Behavior of Textile-Reinforced Concrete

    OpenAIRE

    Volkova Anna; Paykov Alexey; Semenov Sergey; Stolyarov Oleg; Melnikov Boris

    2016-01-01

    This paper deals with the flexural behaviour of textile-reinforced concrete (TRC). Two samples of TRC made of high strength reinforcing fabrics made of glass and carbon rovings were produced. Three-point bending test was carried out to examine the flexural performance of the developed samples. The maximum flexural strength and reinforcement efficiency were calculated. Experimental results showed that that all types of applied fabric reinforcement contributed to increases strength as compared ...

  8. Conformity control of concrete based on the 'Concrete Family' concept

    OpenAIRE

    Caspeele, Robby; Taerwe, Luc

    2008-01-01

    This paper describes how the concept of concrete families can be used for the conformity control of concrete strength. The principles of the concept are explained and an original probabilistic evaluation is introduced. A parameter evaluation approach is explained and the guidelines and conformity criteria for concrete families in EN 206-1 are discussed.

  9. Electrokinetic decontamination of concrete

    Energy Technology Data Exchange (ETDEWEB)

    Lomasney, H. [ISOTRON Corp., New Orleans, LA (United States)

    1995-10-01

    The U.S. Department of Energy has assigned a priority to the advancement of technology for decontaminating concrete surfaces which have become contaminated with radionuclides, heavy metals, and toxic organics. This agency is responsible for decontamination and decommissioning of thousands of buildings. Electrokinetic extraction is one of the several innovative technologies which emerged in response to this initiative. This technique utilizes an electropotential gradient and the subsequent electrical transport mechanism to cause the controlled movement of ionics species, whereby the contaminants exit the recesses deep within the concrete. This report discusses the technology and use at the Oak Ridge k-25 plant.

  10. Danish High Performance Concretes

    DEFF Research Database (Denmark)

    Nielsen, M. P.; Christoffersen, J.; Frederiksen, J.

    1994-01-01

    . The paper includes the results with regard to the mix design, uni- and triaxial strength, creep, shrinkage, and chloride diffusion of HPC. The paper further gives a brief description of the bridge structures in Denmark in which HPC has been utilized. These structures include pedestrian bridges......In this paper the main results obtained in the research program High Performance Concretes in the 90's are presented. This program was financed by the Danish government and was carried out in cooperation between The Technical University of Denmark, several private companies, and Aalborg University...... fume concretes, workability, ductility, and confinement problems....

  11. The Effect of a Plasticizing Admixture on the Properties of Hardened Concrete

    Directory of Open Access Journals (Sweden)

    Anastasija Abasova

    2012-11-01

    Full Text Available Concrete is material obtained mixing matrix material, coarse and small aggregates and water along with additives acquiring necessary properties of hardening. The quality and properties of raw material used for manufacturing concrete, V/C ratio and the uniformity of the compaction of the mixture lead to the fundamental properties of concrete. The compressive strength of concrete is one of the most important properties of concrete. The article deals with the impact of plasticizers on the structural properties of concrete choosing an optimal content of additives. Concrete plasticizers increasing the content of additive increase the strength of samples, the density and ultrasonic pulse of velocity and decrease absorption. Test results have revealed that a plasticizing admixture under dosing or overdosing can reduce the properties of concrete.

  12. Dynamic testing of concrete under high confined pressure. Influence of saturation ratio and aggregate size

    Science.gov (United States)

    Forquin, P.; Piotrowska, E.; Gary, G.

    2015-09-01

    Concrete structures can be exposed to intense pressure loadings such as projectile-impact or detonation near a concrete structural element. To investigate the mechanical behaviour of concrete under high confining pressure, dynamic quasi-oedometric compression tests have been performed with a large diameter (80 mm) Split Hopkinson Pressure Bar apparatus. The concrete sample is placed within a steel confining ring and compressed along its axial direction. Hydrostatic pressures as high as 800 MPa and axial strain of about - 10% are reached during the tests. In the present work, experiments have been conducted on two types of concrete: MB50 microconcrete with a maximum grain size of 2 mm and R30A7 ordinary concrete of maximum grain size about 8 mm. Both concretes are tested in dry or saturated conditions. According to these dynamic experiments it is noted that grain size has a small influence whereas water content has a strong effect on the confined behaviour of concrete.

  13. Recycled aggregate concrete; an overview

    OpenAIRE

    Sorato, Renan

    2016-01-01

    The aim of this Bachelor’s thesis was to investigate whether recycled materials can be incorporated into the production of concrete without compromising the compressive strength of the concrete produced. In order to shed light on the compressive strength of concrete made from recycled materials, the thesis reviewed studies in which waste materials are utilised as recycled aggregates in the composition of concrete and presented the results of this synthesis and analysis. It was found that som...

  14. Self-consolidating concrete homogeneity

    OpenAIRE

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

    2007-01-01

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

  15. 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...

  16. Compressive behaviour of dam concrete at higher strain rates

    Science.gov (United States)

    Caverzan, A.; Peroni, M.; Solomos, G.

    2016-05-01

    The mechanical behaviour of concrete when subjected to impact or blast has still many aspects requiring further study. Dam concrete is characterized by large coarse aggregates, hence large specimen sizes are needed in order to study a representative volume of the material. Exploiting an innovative equipment, based on Hopkinson bar techniques, the dynamic behaviour of concrete of 64 mm maximum aggregate size has been investigated. Direct dynamic compression tests have been performed on medium and large size cylindrical samples. Full stress-strain curves have been obtained, which have allowed the estimation of fracturing energies and of the relevant dynamic increase factor. The experimental campaign has also included a reference standard concrete in order to highlight the peculiarity of the dam concrete at high strain rates and to validate the transition of this type of testing to very large specimens.

  17. Thermal Proprieties of Concrete Lightened by Wood Aggregates

    Directory of Open Access Journals (Sweden)

    D. Taoukil

    2011-02-01

    Full Text Available It is about an experimental study of the thermal proprieties of a concrete lightened by wood aggregates stemming from waste products of the carpentry work. We were especially interested in the comparison between the proprieties of concretes lightened by sawdust and those lightened by wood shavings. The determination of the thermal conductivity and diffusivity of various samples allowed us to demonstrate that the incorporation of wood aggregates in the concrete increases considerably its thermal insulation capacity. Also, we found that, at equal mass percentage of wood aggregates, the concretes elaborated from shavings present thermal insulation capacities better than those obtained from sawdust. On other hand, we have examined the influence of the water content on the thermophysical properties of the studied concretes. So, we have demonstrated and confirmed that the thermal conductivity and diffusivity of the studied materials are strongly dependent on the water content.

  18. Carbonation rates of concretes containing high volume of pozzolanic materials

    Energy Technology Data Exchange (ETDEWEB)

    Kritsada Sisomphon; Lutz Franke [Technical University Hamburg-Harburg, Hamburg (Germany). Department of Building Physics and Building Materials

    2007-12-15

    The project studies the influence of fly ash and slag replacement on the carbonation rate of the concrete. The experimental work includes samples of pure Portland cement concrete (CEM I 42,5 R), blast-furnace slag concrete (CEM III-B), and fly ash blended concrete. To reveal the effect of curing on carbonation rate, the concretes were exposed to various submerged curing periods during their early ages. After that, the samples were subsequently exposed in the climate room controlling 20 {sup o}C and 50% RH until the testing date when the samples had an age of 5 months. Then, the accelerated carbonation test controlling the carbon dioxide concentration of 3% by volume, with 65% relative humidity were started to perform. The depth of carbonation can be observed by spraying a phenolphthalein solution on the fresh broken concrete surface. Finally, according to Fick's law of diffusion theoretical equations are proposed as a guide for estimating the carbonation rate of fly ash and blast-furnace slag concretes exposed under natural conditions from the results from accelerated carbonation tests.

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

    Directory of Open Access Journals (Sweden)

    Sikiru ORITOLA

    2014-11-01

    Full Text Available Gradation plays an important role in the workability, segregation, and pump ability of concrete. Uniformly distributed aggregates require less paste which will also decrease bleeding, creep and shrinkage while producing better workability, more durable concrete and higher packing. This attempt looks at the effect of particle size distribution pattern for five types of gravel aggregate forms, angular, elongated, smooth rounded, irregular and flaky as related to the strength of concrete produced. Different forms of naturally existing gravel aggregate were collected from a particular location and tests were carried out on them to determine their gradation. Based on the gradation the aggregates were used to prepare different samples of grade 20 concrete with water-cement ratio of 0.5. The particle size distribution resulted in coefficients of uniformity ranging from 1.24 to 1.44. The granite aggregate, which serves as a reference, had a coefficient of uniformity of 1.47. Tests were conducted on fresh and hardened concrete cube samples. The concrete sample CT5 recorded a slump of 32mm and highest compressive strength value of 21.7 N/mm2, among the concrete produced from different forms of gravel.

  20. Corrosion Inhibitors for Reinforced Concrete

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Steel corrosion in reinforced concrete structures has been a major problem across the U.S. Steel-reinforced concrete structures are continually subject to attack by corrosion brought on by naturally occurring environmental conditions. FerroGard, a corrosion inhibitor, developed by Sika Corporation, penetrates hardened concrete to dramatically reduce corrosion by 65% and extend the structure's service life.

  1. Thin Concrete Barrel Vault

    NARCIS (Netherlands)

    Kamerling, M.W.

    2013-01-01

    The paper presents the structural design of a thin barrel vault constructed with Fusée Ceramique infill elements. The load transfer is analyzed and validated. For the structure composed of Fusée Ceramique elements, steel and concrete the stresses are calculated and compared to the stresses given in

  2. Electrical pulses protect concrete

    NARCIS (Netherlands)

    Van Kasteren, J.

    2006-01-01

    Even concrete is not as hard as it looks. Sea water, salt on icy roads, and indirectly even carbon dioxide from the air can corrode the steel of the reinforcing bars and so threaten the strength and integrity of a bridge pier, jetty, or viaduct. Dessi Koleva, a chemical engineer from Bulgaria, spent

  3. Concrete peeling off device

    International Nuclear Information System (INIS)

    The present invention concerns a device for peeling off activated concretes in processing for discarding a reactor of a nuclear reactor facility. The device comprises a gyrotron for generation microwaves, an irradiator for irradiating output microwaves, a reflection mirror for reflecting and converging the microwaves and irradiating them to a material to be irradiated and a first rotating means for rotating the irradiator and the reflection mirror in parallel with the axis of the gyrotron while maintaining the positional relation between the irradiator and the reflection mirror. When the position of the microwaves irradiated on concrete walls are moved in a circumferential direction and the central axes of the rotational axis and the material to be irradiated are aligned, then the intensity of the irradiation of the microwaves at each of the irradiation points can be maintained constant without changing the focal distance of the reflected microwaves thereby enabling to peel off concretes efficiently. If operation conditions are controlled based on information such as temperature at the periphery of the microwave irradiation positions, the shape and the color of the material to be irradiated and the distance to the material to be irradiated, a concrete peeling off device of high reliability can be obtained. (N.H.)

  4. Designing concrete for durability

    Directory of Open Access Journals (Sweden)

    Boyd, A. J.

    2001-12-01

    Full Text Available Some of the factors affecting the durability of modern concrete structures are discussed, with an emphasis on the problems caused by modern portland cements. This is followed by a description of some concrete durability issues of current interest, such as plastic shrinkage, seawater attack, and sulfate attack. The strategies for testing for durability are also discussed. It is concluded that, to produce durable concretes, a holistic approach to concrete construction must be adopted.

    Se discuten algunos de los factores que influyen en la durabilidad de las estructuras de hormigón modernas, haciendo énfasis en los problemas causados por el cemento Portland. A esto sigue una descripción de algunas cuestiones de interés general de la durabilidad del hormigón tales como la retracción plástica, el ataque por agua de mar y el ataque por sulfatos. Se discuten también las estrategias de los ensayos de durabilidad. Se concluye que para producir hormigones durables se debe adoptar un enfoque holístico de la construcción con hormigón.

  5. Concentrated loads on concrete

    DEFF Research Database (Denmark)

    Lorenzen, Karen Grøndahl; Nielsen, Mogens Peter

    1997-01-01

    This report deals with concentrated loads on concrete.A new upper bound solution in the axisymmetrical case of a point load in the center of the end face of a cylinder is developed.Based on previous work dealing with failure mechanisms and upper bound solutions, new approximate formulas are...

  6. Continuous Reinforced Concrete Beams

    DEFF Research Database (Denmark)

    Hoang, Cao Linh; Nielsen, Mogens Peter

    1996-01-01

    This report deals with stress and stiffness estimates of continuous reinforced concrete beams with different stiffnesses for negative and positive moments e.g. corresponding to different reinforcement areas in top and bottom. Such conditions are often met in practice.The moment distribution at the...

  7. Radioactivity of cellular concrete

    International Nuclear Information System (INIS)

    The natural radioactivity of cellular concrete is discussed. Some data on the concentrations of 40K, 226Ra and 232Th in building materials in Poland are given. The results of dose rates measurements in living quarters as well as outside are presented. (A.S.)

  8. Teaching concrete structures

    DEFF Research Database (Denmark)

    Goltermann, Per

    2014-01-01

    The teaching of concrete structures has been revised and a number of new approaches have been developed, implemented and evaluated. Inductive teaching, E-learning and “patches” have been found to be improvements and may be an inspiration and help for others development of the teaching and learning...

  9. Contaminated soil concrete blocks

    NARCIS (Netherlands)

    Korte, de A.C.J.; Brouwers, H.J.H.; Limbachiya, Mukesh C.; Kew, Hsein Y.

    2009-01-01

    According to Dutch law the contaminated soil needs to be remediated or immobilised. The main focus in this article is the design of concrete blocks, containing contaminated soil, that are suitable for large production, financial feasible and meets all technical and environmental requirements. In ord

  10. TECHNOLOGY AND EFFICIENCY OF PEAT ASH USAGE IN CEMENT CONCRETE

    Directory of Open Access Journals (Sweden)

    G. D. Liakhevich

    2015-05-01

    Full Text Available One of the main ways to improve physical and mechanical properties of cement concrete is an introduction of ash obtained due to burning of fossil fuels into concrete mix. The concrete mixes with ash are characterized by high cohesion, less water gain and disintegration. At the same time the concrete has high strength, density, water resistance, resistance to sulfate corrosion. The aim of this paper is to explore the possibility to use peat ash and slag of peat enterprises of the Republic of Belarus in the concrete for improvement of its physical and mechanical properties and characteristics of peat ash, slag, micro-silica, cement, superplasticizing agent. Compositions and technology for preparation of concrete mixes have been developed and concrete samples have been have been fabricated and tested in the paper. It has been shown that the concrete containing ash, slag obtained due to burning of peat in the industrial installations of the Usiazhsky and Lidsky Peat Briquette Plants and also MK-85-grade micro-silica NSPKSAUsF-1-grade superplasticizing agent have concrete tensile strength within 78–134 MPa under axial compression and 53 MPa – for the control composition. This index is 1.5–2.5 times more than for the sample containing no additives.The usage of peat ash, slag together with MK-85-grade micro-silica and NSPKSAUsF-1-grade superplasticizing agent for fabrication of concrete and reinforced bridge and tunnel structures will provide the following advantages: reduction of cross-sectional area of structures while maintaining their bearing capacity due to higher value of tensile strength in case of axial compression; higher density, waterand gas tightness due to low water cement ratio; high resistance to aggressive environment due to lower content of capillary pores that ensures bridge structure longevity; achievement of environmental and social impacts.

  11. Properties of high-workability concrete with recycled concrete aggregate

    Directory of Open Access Journals (Sweden)

    Safiuddin

    2011-01-01

    Full Text Available 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 revealed that RCA significantly decreased the workability of concrete. RCA also affected the compressive strength, modulus of elasticity, and permeable voids of concrete. At the age of 28 days, the concrete with 100% RCA provided 12.2% lower compressive strength and 17.7% lesser modulus of elasticity than the control concrete. Also, 100% RCA increased the permeable voids of 28-day old concrete by 8.2%. However, no significant negative impact of RCA was observed on the flexural and splitting tensile strengths of concrete.

  12. Combination Of The Non-Destructive Methods For Evaluating The Quality Of Concrete Used In Structures In Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Mr. R. OBAD

    2014-12-01

    Full Text Available The study is aboutthe use and comparison of three non-destructive methods (dynamic auscultation, sclerometric auscultation and auscultation by RADAR (Radio Detecting and Ranging to monitor and assess the quality of concrete. Samples of reinforced concrete panels, dimensions 200x100x30 cm of concrete dosed at 350 kg/m3 with diverse E/C ratio were achieved, conserved in the laboratory and subjected to various non-destructive test. The synthesis of the results obtained by auscultation RADAR shows a decrease in the propagation speed of the electromagnetic wave with an increase of the E/C ratio and a decrease in resistance of concrete values measured and confirmed by other non-destructive techniques (sclerometric and dynamic auscultations. This shows that more the dielectric constant is high, morethe concrete resistance is reduced, and conversely the opposite.

  13. Performance of Lightweight Concrete based on Granulated Foamglass

    Science.gov (United States)

    Popov, M.; Zakrevskaya, L.; Vaganov, V.; Hempel, S.; Mechtcherine, V.

    2015-11-01

    The paper presents an investigation of lightweight concretes properties, based on granulated foamglass (GFG-LWC) aggregates. The application of granulated foamglass (GFG) in concrete might significantly reduce the volume of waste glass and enhance the recycling industry in order to improve environmental performance. The conducted experiments showed high strength and thermal properties for GFG-LWC. However, the use of GFG in concrete is associated with the risk of harmful alkali-silica reactions (ASR). Thus, one of the main aims was to study ASR manifestation in GFG-LWC. It was found that the lightweight concrete based on porous aggregates, and ordinary concrete, have different a mechanism of ASR. In GFG-LWC, microstructural changes, partial destruction of granules, and accumulation of silica hydro-gel in pores were observed. According to the existing methods of analysis of ASR manifestation in concrete, sample expansion was measured, however, this method was found to be not appropriate to indicate ASR in concrete with porous aggregates. Microstructural analysis and testing of the concrete strength are needed to evaluate the damage degree due to ASR. Low-alkali cement and various pozzolanic additives as preventive measures against ASR were chosen. The final composition of the GFG-LWC provides very good characteristics with respect to compressive strength, thermal conductivity and durability. On the whole, the potential for GFG-LWC has been identified.

  14. Mechanical properties of recycled PET fibers in concrete

    Directory of Open Access Journals (Sweden)

    Fernando Pelisser

    2012-08-01

    Full Text Available Fiber-reinforced concrete represents the current tendency to apply more efficient crack-resistant concrete. For instance, polyethylene terephthalate (PET is a polyester polymer obtained from recyclable bottles; it has been widely used to produce fibers to obtain cement-based products with improved properties. Therefore, this paper reports on an experimental study of recycled-bottle-PET fiber-reinforced concrete. Fibers with lengths of 10, 15 and 20 mm and volume fractions of 0.05, 0.18 and 0.30% related to the volume of the concrete were used. Physical and mechanical characterization of the concrete was performed, including the determination of compressive strength, flexural strength, Young's modulus and fracture toughness as well as analysis using mercury intrusion porosimetry (MIP and scanning electron microscopy (SEM. Flexure and impact tests were performed after 28 and 150 days. No significant effect of the fiber addition on the compressive strength and modulus of elasticity was observed. However, the Young's modulus was observed to decrease as the fiber volume increased. At 28 days, the concrete flexural toughness and impact resistance increased with the presence of PET fibers, except for the 0.05 vol.% sample. However, at 150 days, this improvement was no longer present due to recycled-bottle-PET fiber degradation in the alkaline concrete environment, as visualized by SEM observations. An increase in porosity also has occurred at 365 days for the fiber-reinforced concrete, as determined by MIP.

  15. Crack depth measurement in concrete using diffuse ultrasound

    Science.gov (United States)

    In, Chi Won; Kim, Jin-Yeon; Jacobs, Laurence L.; Kurtis, Kimberly

    2012-05-01

    Cracking in concrete structures is problematic because these cracks can significantly influence the stability of a concrete structure and compromise its durability. The first step to evaluate the serviceability of an in-field concrete structure is to have accurate information on existing crack depth. It is thus of paramount importance to be able to accurately determine the depth of cracks in these concrete structures. This research employs a diffusive ultrasonic technique to measure the depth of surface cracks in concrete. Ultrasonic measurements on a 25.4 × 33 × 60.96 cm3 concrete block containing an artificial crack with varying depths from 2.54 to 10.16 cm are conducted. Contact transducers with one transmitting and the other receiving the ultrasonic signals are mounted on the concrete surface on opposite sides of the crack. A pulse signal with the duration of 2μs is transmitted. In this frequency regime, wavelengths are sufficiently short (comparable with the aggregate size) so that a diffuse ultrasonic signal is detected. The arrival of the diffuse ultrasonic energy at the receiver is delayed by the existence of the crack. This lag-time and the diffusivity of the concrete sample are measured, and a finite element model is employed to solve the inverse problem to determine the crack depth from these measured diffuse ultrasonic parameters.

  16. Study of radon transport through concrete modified with silica fume

    International Nuclear Information System (INIS)

    The concentration of radon in soil usually varies between a few kBq/m3 and tens or hundreds of kBq/m3 depending upon the geographical region. This causes the transport of radon from the soil to indoor environments by diffusion and advection through the pore space of concrete. To reduce indoor radon levels, the use of concrete with low porosity and a low radon diffusion coefficient is recommended. A method of reducing the radon diffusion coefficient through concrete and hence the indoor radon concentration by using silica fume to replace an optimum level of cement was studied. The diffusion coefficient of the concrete was reduced from (1.63 ± 0.3) × 10−7 to (0.65 ± 0.01) × 10−8 m2/s using 30% substitution of cement with silica fume. The compressive strength of the concrete increased as the silica-fume content increased, while radon exhalation rate and porosity of the concrete decreased. This study suggests a cost-effective method of reducing indoor radon levels. -- Highlights: • Radon diffusion study through silica fume modified concrete was carried out. • Radon diffusion coefficient of concrete decreased with increase of silica fume contents. • Compressive strength increased with increase of silica fume. • Radon exhalation rates and porosity of samples decreased with addition of silica fume. • Radon diffusion coefficient decreased to 2.6% by 30% silica fume substitution

  17. Evaluation of the performance of peridotite aggregates for radiation shielding concrete

    International Nuclear Information System (INIS)

    Highlights: • Using peridotite rich in crystal water as aggregates of radiation-shielding concrete. • Performance of peridotite concrete is simulated and compared with ordinary concrete. • Performance of concrete samples is tested. • Neutron shielding performance can be significantly enhanced by peridotite aggregates. - Abstract: Peridotite is a kind of material that is rich in crystal water. In this paper, peridotite is used as fine and coarse aggregates for radiation shielding concrete. The transmission data of different concrete thickness and different energy neutron are calculated using Monte-Carlo method. The neutron shielding performance of the peridotite concrete samples are tested using 241Am-Be neutron source. The results show that the peridotite is an excellent neutron shielding material

  18. Characterization of gas concrete materials used in buildings of Turkey

    International Nuclear Information System (INIS)

    The activity concentration of 226Ra, 232Th and 40K in gas concrete samples collected from different suppliers and some provinces in Turkey were measured using gamma-ray spectrometry. Knowledge of radioactivity in gas concrete used in building materials enables one to assess any possible radiological risks to human health. The mean activity concentrations observed in the gas concrete samples were 82.0, 28.2 and 383.9 Bq kg-1 for 226Ra, 232Th and 40K, respectively. The radium equivalent activity, external and internal hazard indices as well as terrestrial absorbed dose and annual effective dose rate was calculated. The results indicate that the radium equivalent activity values of gas concrete samples are lower than the limit of 370 Bq kg-1, equivalent to a gamma-dose of 1.5 mSv y-1. Moreover, mass attenuation coefficients were measured in some gas concrete samples. It was found that the mass attenuation coefficients decreased with increasing photon energies. Also, chemical compositions and structural analysis (XRD and SEM) of the gas concrete samples were investigated.

  19. Characterization of gas concrete materials used in buildings of Turkey.

    Science.gov (United States)

    Damla, N; Cevik, U; Kobya, A I; Celik, A; Van Grieken, R; Kobya, Y

    2009-09-15

    The activity concentration of (226)Ra, (232)Th and (40)K in gas concrete samples collected from different suppliers and some provinces in Turkey were measured using gamma-ray spectrometry. Knowledge of radioactivity in gas concrete used in building materials enables one to assess any possible radiological risks to human health. The mean activity concentrations observed in the gas concrete samples were 82.0, 28.2 and 383.9 Bq kg(-1) for (226)Ra, (232)Th and (40)K, respectively. The radium equivalent activity, external and internal hazard indices as well as terrestrial absorbed dose and annual effective dose rate was calculated. The results indicate that the radium equivalent activity values of gas concrete samples are lower than the limit of 370 Bq kg(-1), equivalent to a gamma-dose of 1.5 mSv y(-1). Moreover, mass attenuation coefficients were measured in some gas concrete samples. It was found that the mass attenuation coefficients decreased with increasing photon energies. Also, chemical compositions and structural analysis (XRD and SEM) of the gas concrete samples were investigated. PMID:19297097

  20. Gas and Water Permeability of Concrete

    Energy Technology Data Exchange (ETDEWEB)

    Villar, M. V.; Martin, P. L.; Romero, F. J.; Gutierrez-Rodirgo, V.; Barcala, J. M.

    2012-11-01

    The gas pressure of concrete samples was measured in an unsteady-state equipment working under low injection pressures and in a newly fine tuned steady-state setup working under different pressures. These measurements allowed the estimation of the intrinsic and relative gas permeability of the concrete and of the effect of boundary conditions on them. Permeability decreased with water content, but it was also greatly affected by the hydraulic history of concrete, i.e. if it had been previously dried or wetted. In particular, and for a given degree of saturation, the gas permeability of concrete previously saturated was lower than if the concrete had been just air dried or saturated after air drying. In any case, the gas permeability was about two orders of magnitude higher than the liquid water permeability (10-16 vs. 10-18 m2), probably due to the chemical reactions taking place during saturation (carbonation). The relative gas permeability of concrete increased sharply for water degrees of saturation smaller than 50%. The boundary conditions also affected the gas permeability, which seemed to be mostly conditioned by the back pressure and the confining pressure, increasing as the former increased and decreasing as the latter increased, i.e. decreasing as the effective pressure increased. Overall the increase of pressure head or injection pressure implied a decrease in gas permeability. External,microcracking during air-drying could not be ruled out as responsible for the decrease of permeability with confining pressure. The apparent permeability obtained applying the Klinkenberg method for a given effective pressure was only slightly smaller than the average of all the values measured for the same confining pressure range. For this reason it is considered that the Klinkenberg effect was not relevant in the range of pressures applied. (Author) 37 refs.

  1. Innovative technology summary report: Concrete grinder

    International Nuclear Information System (INIS)

    The Flex concrete grinder is a lightweight, hand-held concrete and coating removal system used for decontaminating or stripping concrete surfaces. The US Department of Energy has successfully demonstrated it for decontaminating walls and floors for free release surveys prior to demolition work. The grinder is an electric-powered tool with a vacuum port for dust extraction and a diamond grinding wheel. The grinder is suitable for flat or slightly curved surfaces and results in a smooth surface, which makes release surveys more reliable. The grinder is lightweight and produces very little vibration, thus reducing worker fatigue. The grinder is more efficient than traditional baseline, tools at removing contamination from concrete surfaces (more than four times faster than hand-held pneumatic scabbling and scaling tools). Grinder consumables (i.e., replacement diamond grinding wheel) are more expensive than the replacement carbide parts for the scaler and scabbler. However, operating costs are outweighed by the lower purchase price of the grinder (50% of the price of the baseline scaler and 8% of the price of the baseline scabbler). Overall, the concrete grinder is an attractive alternative to traditional scabbling and scaling pneumatic tools. To this end, in July 1998, the outer rod room exposed walls of the Safe Storage Enclosure (SSE), an area measuring approximately 150 m2, may be decontaminated with the hand-held grinder. This concrete grinder technology was demonstrated for the first time at the DOE's Hanford Site. Decontamination of a sample room walls was performed at the C Reactor to free release the walls prior to demolition. The demonstration was conducted by onsite D and D workers, who were instructed by the vendor prior to and during the demonstration

  2. 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.

  3. 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...

  4. Corrosion of steel reinforced concrete in the tropical coastal atmosphere of Havana City, Cuba

    Directory of Open Access Journals (Sweden)

    Abel Castañeda

    2013-01-01

    Full Text Available The influence of chloride deposition rate on concrete using an atmospheric corrosion approach is rarely studied in the literature. Seven exposure sites were selected in Havana City, Cuba, for exposure of reinforced concrete samples. Two significantly different atmospheric corrosivity levels with respect to corrosion of steel reinforced concrete were observed after two years of exposure depending on atmospheric chloride deposition and w/c ratio of the concrete. Changes in corrosion current are related to changes in chloride penetration and chloride atmospheric deposition. The influence of sulphur compound deposition could also be a parameter to consider in atmospheric corrosion of steel reinforced concrete.

  5. Effect of Thermal Cycling on the Strength and Texture of Concrete for Nuclear Safety Structures

    Directory of Open Access Journals (Sweden)

    Š. Hošková

    2001-01-01

    Full Text Available The effect of thermal cycling (freezing and thawing on the texture and strength of two types of concrete is studied: 1. Concrete used for a containment structure at NPP Temelín (Czech Republic - so-called TEMELÍN concrete.2. Highly resistant PENLY concrete, which was used as a standard because of its high quality, proved by the research carried out in a European Commission project. The results for the two samples of concrete are compared.

  6. 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.

  7. EXPERIMENTAL INVESTIGATION OF COMPRESSYVE STRENGTH AND PHYSICAL PROPERTIES OF CONCRETE PRODUCED WITH GROUND BARITE

    OpenAIRE

    ESEN, Yüksel; ORHAN, Eyyüp; Kurt, Alper

    2011-01-01

    ABSTRACT In this study, compressive strength test and physical tests were made on concrete which was produced by using ground barite provided from Foreign Trade Inc. in Mu? province. Two different procedures were used in the experiments. In the first, concrete samples were prepared by decreasing the amount of aggregate in concrete mix at the rates of 20%, 40%, 60%, 80% and 100%, respectively, and by adding ground barite at the same proportions. In the second, the samples were prepared by sub...

  8. Performance of Recycled Aggregate Concrete Containing Micronised Biomass Silica

    Directory of Open Access Journals (Sweden)

    Suraya Hani Adnan

    2011-07-01

    Full Text Available This paper presents a study on Micronised Biomass Silica (MBS that was produced from the controlled burning of waste Rice Husk. The MBS was used as pozzolan material to enhance the performance of Recycled Aggregate Concrete (RAC. Various percentages by mass of Micronised Biomass Silica were applied in the normal and recycled aggregate concrete cube samples. Compressive strength and water permeability tested on the samples at the age of 7, 14, 28 and 90 days showed that concrete containing MBS has attained higher compressive strength. Furthermore, the test on MBS also showed its ability to enhance the concrete water permeability. Lengthen to this; the study established a good correlation between the MBS content with compressive strength and water permeability coefficient.

  9. Physical and microstructural aspects of iron sulfide degradation in concrete

    International Nuclear Information System (INIS)

    The microstructural aspects of iron sulfide degradation in dam concrete were investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) in both dam concrete samples and laboratory concrete. The results show that iron sulfide inclusions with a diameter of a few micrometers in the aggregates are reactive and appear to generate expansion first in the aggregates and consequently in the cement paste. The expansion from the iron sulfides is a consequence of the increase in volume of the reaction products formed. The types of iron sulfide present in the aggregate, mainly pyrrhotite (FeS) and pyrite (FeS2), show similar reaction behavior in the aggregates. The released sulfate can lead to a secondary ettringite formation in the concrete matrix, but the degradation associated with this appears to be minor. The reaction of the iron sulfides was found to be very slow even when laboratory samples were exposed to elevated temperatures.

  10. Micro Environmental Concrete

    Science.gov (United States)

    Lanez, M.; Oudjit, M. N.; Zenati, A.; Arroudj, K.; Bali, A.

    Reactive powder concretes (RPC) are characterized by a particle diameter not exceeding 600 μm and having very high compressive and tensile strengths. This paper describes a new generation of micro concrete, which has an initial as well as a final high physicomechanical performance. To achieve this, 15% by weight of the Portland cement have been substituted by materials rich in Silica (Slag and Dune Sand). The results obtained from the tests carried out on the RPC show that compressive and tensile strengths increase when incorporating the addition, thus improving the compactness of mixtures through filler and pozzolanic effects. With a reduction in the aggregate phase in the RPC and the abundance of the dune sand (southern of Algeria) and slag (industrial by-product of the blast furnace), the use of the RPC will allow Algeria to fulfil economical as well as ecological requirements.

  11. Drilling waste makes concrete

    International Nuclear Information System (INIS)

    The article deals with a method of drilling waste reclamation by utilizing the converted oil-containing cuttings from the North Sea in the concrete production in Norway. The oil content is to be removed in an incineration process by heating the cuttings to about 800oC. The output capacity from the exhaust gas water cooling system is 7500 kW/hour, and is to be used in different industrial heating processes. The remaining content of pollutants in the cleaned exhaust gas outlet corresponds to the required limits with the exception of SO2 and HCl. In addition, an exhaust gas washing plant is to be installed in the near future designed for the further reduction of pollutants by 90%. The converted raw materials are used as a supplement for lessening the demand of sand and cement in the production of concrete-made pipes. 1 fig

  12. Hypervelocity impact of concrete

    International Nuclear Information System (INIS)

    Blocks of concrete and various other materials were impacted by high speed copper jets at the centre of one face, the resulting transient phenomena were measured using ultra high speed photography and various electrical signal transducers. Measurements were made of the jet velocity, penetration rate, crack velocity and initiation time, and strain pulse propagation. Post test measurements were made using electron microscopy, ultra sonics and stereoscopic photography. (orig.)

  13. Sulfur 'Concrete' for Lunar Applications - Environmental Considerations

    Science.gov (United States)

    Grugel, R. N.

    2008-01-01

    Commercial use of sulfur concrete on Earth is well established, particularly in corrosive, e.g., acid and salt, environments. Having found troilite (FeS) on the Moon raises the question of using extracted sulfur as a lunar construction material, an attractive alternative to conventional concrete as it does not require water. For the purpose of this Technical Memorandum, it is assumed that lunar ore is mined, refined, and the raw sulfur processed with appropriate lunar regolith to form, for example, bricks. With this stipulation, it is then noted that the viability of sulfur concrete in a lunar environment, which is characterized by lack of an atmosphere and extreme temperatures, is not well understood. The work presented here evaluates two sets of small sulfur concrete samples that have been prepared using JSC-1 lunar simulant as an aggregate addition. One set was subjected to extended periods in high vacuum to evaluate sublimation issues, and the other was cycled between room and liquid nitrogen temperatures to investigate their subsequent mechanical integrity. Results are presented from both investigations, discussed, and put into the context of the lunar environment.

  14. 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.

  15. Radiolysis of concrete

    International Nuclear Information System (INIS)

    A computer based radiation chemical program has been used to simulate experiments with gamma and alpha radiolysis in concrete. The experiments have been performed at Savannah River by Ned Bibler and co-workers. The calculations showed that the gas yields were very sensitive to the pH of the water phase. At a pH of 12.3 fairly good agreement was obtained between measured and calculated gas yields, assuming that the gas production only took place in the free water phase of the concrete. The following main conclusions could be made from both measurements and calculations: 1/ A steady state is obtained by gamma radiolysis of a NO3 free concrete. 2/ The yields are higher and a steady state is not obtained if NO3 is present. The yields are higher and a steady state is not obtained by alpha radiolysis. Calculations were also carried out on radiolysis from cladding hull waste stored in a cement matrix assuming both alpha and beta radiation. In the presence of an aerated gas phase a steady state pressure of more than 0.21 MPa was obtained.(author)

  16. Non-stress related deformation of furfuryl alcohol polymer concrete

    OpenAIRE

    Kruger, D.

    1990-01-01

    In this study attention is given to the deformation performance of furfuryl alcohol polymer concrete during and directly after polymerisation. The deformation equations of ordinary Portland cement concrete are used as a model, while the appropriate adjustment is made to bring the effect of polymerisation shrinkage into consideration. Experimental work was done to deter­mine the deformation characteristics of material samples which were exposed to various temperature conditions, while being ...

  17. Towards Better Understanding of Concrete Containing Recycled Concrete Aggregate

    OpenAIRE

    Hisham Qasrawi; Iqbal Marie

    2013-01-01

    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...

  18. Repercussions on concrete permeability due to recycled concrete aggregate

    OpenAIRE

    Gómez Soberón, José Manuel Vicente; Agulló Fité, Luís; Vázquez Ramonich, Enric

    2001-01-01

    This paper presents an experimental analysis of recycled concrete (RC) in which the natural aggregates are replaced by recycled concrete aggregates (RCA). This experimental program covers the specifications of the aggregates employed, together with that of the concrete that is manufactured with them. The considerable effect on the permeability of RC that is produced by the use of RCA is described and discussed. Tests reveal considerable increase in permeability of RC in compari...

  19. Concrete Sawing Waste Recycling As Microfiller in Concrete Production

    OpenAIRE

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

    2015-01-01

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

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

    International Nuclear Information System (INIS)

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

  1. Stabilization of electric-arc furnace dust in concrete

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Caldas de Souza

    2010-12-01

    Full Text Available Electric-arc furnace dust (EAFD is a by-product of steel production and recycling. This fine-grained material contains high amounts of zinc and iron as well as significant amounts of potentially toxic elements such as lead, cadmium and chromium. Therefore, the treatment and stabilization of this industrial residue is necessary. Concrete is a well-known suitable environment for stabilization/solidification of materials which have leachable elements in need of fixation. The effect of the EAFD content on the mechanical and chemical performance of Portland cement concrete is investigated in this paper. The effect of the EAFD content on the setting time of cement slurry was also analyzed. The axial compressive strength of the concrete samples increases with the EAFD addition in the range of 10 to 20 wt. (% EAFD; also the tensile strength increases with the EAFD addition. An increase in EAFD content significantly increases the setting time of the concrete. The acetic acid leaching and water solubilization tests indicate low mobility of the potentially toxic elements from the EAFD concrete composite. The results of the immersion tests show that the addition of EAFD to the concrete seems to reduce chloride penetration, which may help prevent pitting corrosion in reinforced concrete.

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

    Science.gov (United States)

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

    2012-12-01

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

  3. Nanogranular origin of concrete creep

    OpenAIRE

    Vandamme, Matthieu; Ulm, Franz-Josef

    2009-01-01

    Concrete, the solid that forms at room temperature from mixing Portland cement with water, sand, and aggregates, suffers from time-dependent deformation under load. This creep occurs at a rate that deteriorates the durability and truncates the lifespan of concrete structures. However, despite decades of research, the origin of concrete creep remains unknown. Here, we measure the in situ creep behavior of calcium–silicate–hydrates (C–S–H), the nano-meter sized particles that form the fundament...

  4. ASSESSMENT OF RECYCLED AGGREGATE CONCRETE

    OpenAIRE

    Ahmad Mujahid Ahmad Zaidi

    2009-01-01

    Used of recycled aggregate (RA) in concrete can be described in environmental protection and economical terms. The application of recycled aggregate to use in construction activities have been practice by developed European countries and also of some Asian countries. This paper reports the results of an experimental study on the mechanical properties of recycled aggregate concrete (RAC) as compared to natural aggregate concrete (NAC). The effects of size of RA on compressive strength were dis...

  5. Concrete durability with antigraffiti protection

    OpenAIRE

    Neto, Elsa; Souto, Ana; Camões, Aires; Begonha, Arlindo; Cachim, Paulo

    2014-01-01

    The heritage of fair-faced concrete, largely built in the twentieth century and nowadays recognized as heritage to be protected, is susceptible to attacks by graffiti. Durability of concrete depends on the composition and characteristics of the surface, whereby it is essential to study the effects of anti-graffiti protection systems on the durability of concrete and adopt the appropriate methodology to preserve this heritage. Thus, an experimental program was developed for analyzing changes i...

  6. Inspection Strategies for Concrete Bridges

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Thoft-Christensen, Palle

    In this paper an optimal inspection strategy for concrete bridges based on periodic routine and detailed inspections is presented. The failure mode considered is corrosion of the reinforcement due to chlorides. A simple modelling of the corrosion and of the inspection strategy is presented. The...... optimal inspection strategy is determined from an optimization problem, where the design variables are time intervals between detailed inspections and the concrete cover. The strategy is illustrated on a simple structure, namely a reinforced concrete beam....

  7. Diagnosing delayed ettringite formation in concrete structures

    International Nuclear Information System (INIS)

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

  8. 221-U Facility concrete and reinforcing steel evaluations specification for the canyon disposition initiative (CDI)

    International Nuclear Information System (INIS)

    This describes a test program to establish the in-situ material properties of the reinforced concrete in Building 221-U for comparison to the original design specifications. Field sampling and laboratory testing of concrete and reinforcing steel structural materials in Building 221-U for design verification will be undertaken. Forty seven samples are to be taken from radiologically clean exterior walls of the canyon. Laboratory testing program includes unconfined compressive strength of concrete cores, tensile strength of reinforcing steel, and petrographic examinations of concrete cores taken from walls below existing grade

  9. Mechanical Properties and Durability of "Waterless Concrete"

    Science.gov (United States)

    Toutanji, Houssam; Grugel, Richard N.

    2008-01-01

    Waterless concrete consists of molten elementary sulfur and aggregate. The aggregates in lunar environment will be lunar rocks and soil. Sulfur is present on the Moon in Troilite soil (FeS) and by oxidation soil iron and sulfur can be produced. Iron can be used to reinforce the sulfur concrete. Sulfur concrete specimens were cycled between liquid nitrogen (approximately 191 C) and room temperature (approximately 21 C) to simulate exposure to a lunar environment. Cycled and control specimens were subsequently tested in compression at room temperatures (approximately 21 C) and approximately 101 C. Test results showed that due to temperature cycling, compressive strength of cycled specimens was 20% of those non-cycled. Microscopic examination of the fracture surfaces from the cycled samples showed clear de-bonding of the sulfur from the aggregate material whereas it was seen well bonded in those non-cycled. This reduction in strength can be attributed to the large differences in thermal coefficients of expansion of the materials constituting the concrete which promoted cracking. Similar sulfur concrete mixtures were strengthened with short and long glass fibers. The glass fibers from lunar regolith simulant was melted in a 25 cc Pt-Rh crucible in a Sybron Thermoline high temperature MoSi2 furnace at melting temperatures of 1450 to 1600 C for times of 30 min to 1 hour. Glass fibers were cast from the melt into graphite crucibles and were annealed for a couple of hours at 600 C. Glass fibers and small rods were pulled from the melt. The glass melt wets the ceramic rod and long continuous glass fibers were easily hand drawn. The glass fibers were immediately coated with a protective polymer to maintain the mechanical strength. The glass fibers were used to reinforce sulfur concrete plated to improve the flexural strength of the sulfur concrete. Prisms beams strengthened with glass fibers were tested in 4-point bending test. Beams strengthened with glass fiber showed to

  10. TECHNOLOGICAL PROPERTIES OF CONCRETES AND MORTARS FOR UNDERWATER CONCRETING

    OpenAIRE

    O. V. Anufrieva; B. H. Klochko

    2009-01-01

    The article is about the results of experimental-and-theoretical research of usefulness of mortar and concrete mixes for underwater repair works. It is shown that the developed compositions of hydraulic engineering concretes are characterized by high effectiveness in the corrosive medium.

  11. TECHNOLOGICAL PROPERTIES OF CONCRETES AND MORTARS FOR UNDERWATER CONCRETING

    Directory of Open Access Journals (Sweden)

    O. V. Anufrieva

    2009-03-01

    Full Text Available The article is about the results of experimental-and-theoretical research of usefulness of mortar and concrete mixes for underwater repair works. It is shown that the developed compositions of hydraulic engineering concretes are characterized by high effectiveness in the corrosive medium.

  12. Electrical pulses protect concrete

    OpenAIRE

    Van Kasteren, J.

    2006-01-01

    Even concrete is not as hard as it looks. Sea water, salt on icy roads, and indirectly even carbon dioxide from the air can corrode the steel of the reinforcing bars and so threaten the strength and integrity of a bridge pier, jetty, or viaduct. Dessi Koleva, a chemical engineer from Bulgaria, spent her doctoral research at the Faculty of Civil Engineering and Geosciences devising a method for the cathodic protection of steel rebars. The method is cheaper and also has fewer side effects on th...

  13. Thin Concrete Barrel Vault

    OpenAIRE

    Kamerling, M.W.

    2013-01-01

    The paper presents the structural design of a thin barrel vault constructed with Fusée Ceramique infill elements. The load transfer is analyzed and validated. For the structure composed of Fusée Ceramique elements, steel and concrete the stresses are calculated and compared to the stresses given in the codes used from 1950 to the present. The advantages and disadvantages of these low rise barrel vaults are showed. Further the possibilities of a light infill to reduce, for structures of concre...

  14. Design and Simulation of Concrete Reinforced with Fiber as a Shield to Gamma and Neutron Radiations

    Directory of Open Access Journals (Sweden)

    Marzieh Salimi

    2013-10-01

    Full Text Available In this paper, the goal is to design and simulate some concrete samples reinforced with Fiber as well as containing Bohr in order to be utilized as a shield to nuclear radiations (Gamma & Neutron.by presenting experimental composing projects for heavy and ordinary concrete containing Bohr ,heavy and ordinary concrete reinforced with Fiber , proper ratios for stuff were computed. Then using nuclear computations with computational code of MCNPX for Neutron and Gamma`s radiant spectra, the required Bohr, polypropylene Fiber, and steel percentages were obtained in order to be used in plain, Fiber, and heavy concrete material. In the next stage, ten concrete samples were analyzed in final experiments. Finally, reinforced concrete material weakening coefficients using MCNPX code were computed and the level of Neutron and Gamma radiating for every composing project was separately attained.

  15. Use of combined destructive and non-destructive test methods to assess the strength of concrete

    International Nuclear Information System (INIS)

    The compressive strength test applied on standard samples is one of the most important tests indicating the quality of concrete in structures. The results of the standard tests are compared with the values used in design calculations and the quality of concrete is controlled. Although the standard tests are well accepted by the construction industry, they may not represent the in-situ strength of concrete due to the differences between the degree of compaction and curing conditions of concrete and those of standard samples. In-situ strength is also important for the efficient planning of the construction works in huge projects. In the present study, the results obtained from standard tests, core tests, ultrasonic pulse velocity tests, and rebound hammer tests were extensively analysed for the assessment of concrete strength. Key words: Concrete strength, standard tests, core test, ultrasonic pulse velocity, rebound number

  16. Preliminary study of neutron absorption by concrete with boron carbide addition

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah, Yusof, E-mail: yusofabd@nuclearmalaysia.gov.my; Yusof, Mohd Reusmaazran; Zali, Nurazila Mat; Ahmad, Megat Harun Al Rashid Megat; Yazid, Hafizal [Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia); Ariffin, Fatin Nabilah Tajul; Ahmad, Sahrim [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor (Malaysia); Hamid, Roszilah [Department of Civil and Structural Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor (Malaysia); Mohamed, Abdul Aziz [College of Engineering, Universiti Tenaga National, Jalan Ikram-Uniten, 43000 Kajang, Selangor (Malaysia)

    2014-02-12

    Concrete has become a conventional material in construction of nuclear reactor due to its properties like safety and low cost. Boron carbide was added as additives in the concrete construction as it has a good neutron absorption property. The sample preparation for concrete was produced with different weight percent of boron carbide powder content. The neutron absorption rate of these samples was determined by using a fast neutron source of Americium-241/Be (Am-Be 241) and detection with a portable backscattering neutron detector. Concrete with 20 wt % of boron carbide shows the lowest count of neutron transmitted and this indicates the most neutrons have been absorbed by the concrete. Higher boron carbide content may affect the concrete strength and other properties.

  17. Behavior of Plastic Concrete Diaphragm Walls in Three Gorges Project

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The high earth and rockfill cofferdam of Three Gorges Project employs plastic co ncrete diaphragm walls as seepage barrier. In view of the importance and technic al difficulty of the cofferdams, the behavior of plastic concrete and the diaphr agm walls within the cofferdams was studied. Plastic concrete samples taken from concrete mixer in the dam site were tested by using large triaxial testing appa ratus in Tsinghua University. Mechanical properties and parameters of Duncan-Ch ang nonlinear elastic model were obtained. Test results indicated that, comparin g with ordinary concrete, the mate rials have the features of low modulus of deformation and favorable impermeabili t y. The analysis of stresses and deformations of the diaphragm walls was performe d by means of finite element method (FEM), using parameters obtained from the re sult of triaxial tests. Calculation results were discussed.

  18. Effects of remote drop and pumpdown placement on cellular concrete

    International Nuclear Information System (INIS)

    The hazards to the public posed by abandoned mine shafts are well documented. As private development encroaches on previously mined areas, the potential for fatalities and serious injuries from abandoned mine shafts increases. The US Bureau of Mines has conducted research into cellular concrete as a material for sealing these openings. The current work involves testing the characteristics of cellular concrete before and after it had been pumped or dropped from different heights into a simulated mine shaft. Cellular concrete was pumped vertically up to and subsequently dropped from heights of 18 and 37 m into concrete forms. Wet density measurements were made at multiple sampling points in the test circuit. Air content determinations and uniaxial compressive strength testing were conducted. Research results are discussed

  19. Experimental Investigation of Shrinkage of Nano Hair Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Yadollah Batebi

    2013-01-01

    Full Text Available Basically most of cement based mixtures are likely shrinking. Use of fibers is not a new idea in this case. Previously, there were some evidences that horse hair, straw and cotton fibers were used in mud and mortars in ancient times. Then, utilizing these fibers in concrete mixture may increase concrete workability and decrease shrinkage cracks. Due to nano cross-section of hair and its proper tensile strength this project investigates its application to reduce the shrinkage of concrete mixtures. For this purpose, human hair fibers were used in 0.4 and 0.8 and 1.2 weight percent and the length of the fibers in each case varied between 15 and 60 millimeter and the samples were made of dimensions of 40×40×160 millimeters. Results are shown as considerable amount of hair may reduce in the shrinkage in the hair reinforced concrete.

  20. Bond Strength Degradation of Corrosive Reinforced Lightweight Concrete

    Institute of Scientific and Technical Information of China (English)

    CHEN Yueshun; LU Yiyan; LI Houxiang; ZENG Sanhai

    2007-01-01

    The influence of reinforced bar corrosion on the bond degradation in lightweight concrete was studied. Accelerated constant current corrosion tests were performed on lightweight reinforced concrete samples, and the influential factors, such as protective layer thickness, reinforced bar diameter and corrosive level were investigated. The constant current step method was used to measure the electric resistance of the concrete protective cover, which was used to characterize the corrosion level of the rebar. Experimental results indicated that the corrosive resistance increased with increasing the cover dimension and decreasing the reinforced bar diameter, and the rate of decrease in the specimen impedance after cracking depended on the cover dimension. A new medium was offered for the further research on the performance degradation of corrosion lightweight concrete.

  1. Physio-chemical reactions in recycle aggregate concrete.

    Science.gov (United States)

    Tam, Vivian W Y; Gao, X F; Tam, C M; Ng, K M

    2009-04-30

    Concrete waste constitutes the major proportion of construction waste at about 50% of the total waste generated. An effective way to reduce concrete waste is to reuse it as recycled aggregate (RA) for the production of recycled aggregate concrete (RAC). This paper studies the physio-chemical reactions of cement paste around aggregate for normal aggregate concrete (NAC) and RAC mixed with normal mixing approach (NMA) and two-stage mixing approach (TSMA) by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Four kinds of physio-chemical reactions have been recorded from the concrete samples, including the dehydration of C(3)S(2)H(3), iron-substituted ettringite, dehydroxylation of CH and development of C(6)S(3)H at about 90 degrees C, 135 degrees C, 441 degrees C and 570 degrees C, respectively. From the DSC results, it is confirmed that the concrete samples with RA substitution have generated less amount of strength enhancement chemical products when compared to those without RA substitution. However, the results from the TSMA are found improving the RAC quality. The pre-mix procedure of the TSMA can effectively develop some strength enhancing chemical products including, C(3)S(2)H(3), ettringite, CH and C(6)S(3)H, which shows that RAC made from the TSMA can improve the hydration processes. PMID:18718710

  2. Durability of concrete in saline environment

    OpenAIRE

    1996-01-01

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

  3. Development of Concrete Shrinkage Performance Specifications

    OpenAIRE

    Mokarem, David Wayne

    2002-01-01

    During its service life, concrete experiences volume changes. One of the types of deformation experienced by concrete is shrinkage. The four main types of shrinkage associated with concrete are plastic, autogeneous, carbonation and drying shrinkage. The volume changes in concrete due to shrinkage can lead to the cracking of the concrete. In the case of reinforced concrete, the cracking may produce a direct path for chloride ions to reach the reinforcing steel. Once chloride ions reach th...

  4. Nuclear radiation and the properties of concrete

    International Nuclear Information System (INIS)

    Concrete is used for structures in which the concrete is exposed to nuclear radiation. Exposure to nuclear radiation may affect the properties of concrete. The report mentions the types of nuclear radiation while radiation damage in concrete is discussed. Attention is also given to the effects of neutron and gamma radiation on compressive and tensile strength of concrete. Finally radiation shielding, the attenuation of nuclear radiation and the value of concrete as a shielding material is discussed

  5. Interface Microstructures in Concrete

    Directory of Open Access Journals (Sweden)

    Puertas, Francisca

    1991-03-01

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

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

  6. The concrete canister program

    International Nuclear Information System (INIS)

    In the spring of 1974, WNRE began development and demonstration of a dry storage concept, called the concrete canister, as a possible alternative to storage of irradiated CANDU fuel in water pools. The canister is a thick-walled concrete monolith containing baskets of fuel in the dry state. The decay heat from the fuel is dissipated to the environment by natural heat transfer. Four canisters were designed and constructed. Two canisters containing electric heaters have been subjected to heat loads of 2.5 times the design, ramp heat-load cycling, and simulated weathering tests. The other two canisters were loaded with irradiated fuel, one containing fuel bundles of uniform decay heat and the other containing bundles of non-uniform decay heat in a non-symmetrical radial and axial array. The collected data were used to verify the analytical tools for prediction of effectiveness of heat transfer and radiation shielding and to verify the design of the basket and canisters. The demonstration canisters have shown that this concept is a viable alternative to water pools for the storage of irradiated CANDU fuel. (author)

  7. The effect of polypropylene fibres within concrete with regard to fire performance in structures

    OpenAIRE

    Richardson, Alan; Dave, Urmil V.

    2008-01-01

    Purpose – The purpose of this paper is to examine the effect of various polypropylene fibre additions (types and volume) to concrete with regard to explosive spalling when subject to high temperatures similar to those experienced in building or tunnel fires. Design/methodology/approach – Medium strength concrete was manufactured with varying proportions of polypropylene fibres. Plain control samples were used to determine the original concrete strength and this was used as a benchmark fo...

  8. Laboratory research on disintegration of concretes exposed to high temperature by water jets

    OpenAIRE

    Sitek, L. (Libor); Bodnárová, L.; J. Klich; Foldyna, J.; Hlaváček, P.; Zeleňák, M.

    2013-01-01

    The paper is dealing with effects of flat high-speed water jet on concretes affected by high temperature. Several concrete mixtures were prepared for tests of interaction of water jet with concrete samples: 1)unaffected by high temperature, 2)exposed to 200°C and 3)exposed to 600°C- Achieved results are analyzed and discussed. Research should help especially after wildfires in tunnels, underground garages, etc., which are exposed to enormous thermal stress.

  9. Mechanical Properties of Lightweight Concrete Partition with a Core of Textile Waste

    Directory of Open Access Journals (Sweden)

    Kamran Aghaee

    2013-01-01

    Full Text Available This investigation is focused on bending experiment of some prismatic perlite lightweight concrete. In these samples, textile waste fibers are confined with textile mesh glass fiber and embedded in the central part of cubic lightweight concrete specimens. Bending experiments revealed that lightweight concrete panels with a core of textile waste fiber have less density than water and high energy absorption and ductility. Furthermore, these composite panels by having appropriate thermal insulation characteristics could be used for partitioning in the buildings.

  10. Influences of Fly Ash on Concrete Product's Properties and Environmental Impact Reduction

    OpenAIRE

    Thipsuree Kornboonraksa; Thirdpong Srisukphun

    2015-01-01

    This research aimed to study effects of incorporating fly ash into concrete products. Scope of this study were (1) hazard identification of fly ash (2) study on standard testing of various concrete products and (3) study on environmental impact assessment of concrete products mixed with fly ash. Various types of fly ash namely A, B, C and D were sampling from different power plants. Hazard identification of fly ash was analyzed in terms of total threshold limit concentration (TTLC) and solubl...

  11. Mechanical Properties of Lightweight Concrete Partition with a Core of Textile Waste

    OpenAIRE

    Kamran Aghaee; Mohammad Foroughi

    2013-01-01

    This investigation is focused on bending experiment of some prismatic perlite lightweight concrete. In these samples, textile waste fibers are confined with textile mesh glass fiber and embedded in the central part of cubic lightweight concrete specimens. Bending experiments revealed that lightweight concrete panels with a core of textile waste fiber have less density than water and high energy absorption and ductility. Furthermore, these composite panels by having appropriate thermal insulat...

  12. Chemo-mechanical coupling behaviour of leached concrete. Part I : Experimental results

    OpenAIRE

    NGUYEN,VH; COLINA, H; Torrenti, Jean Michel; Boulay, Claude; Nedjar, Boumediene

    2007-01-01

    This paper deals with concrete behaviour under chemical and mechanical degradations. Experimental investigations are described where the effects of the calcium leaching process of concrete on its mechanical properties are highlighted. The calcium leaching and mechanical tests on cement paste, mortar and concrete samples are presented. Because of the slow kinetics of leaching under deionised water, an accelerated method has been chosen by using an ammonium nitrate solution instead. The specime...

  13. The Concrete and Pavement Challenge

    Science.gov (United States)

    Roman, Harry T.

    2012-01-01

    The modern world is characterized by the extensive use of concrete and asphalt pavement. Periodically, these materials are replaced and the old materials disposed of. In this challenge, students will be asked to develop ways to reuse the old materials. It is important for students to understand how concrete and asphalt are made and applied, as…

  14. Wood and concrete polymer composites

    International Nuclear Information System (INIS)

    There are several ways to prepare and use wood and concrete polymer composites. The most important improvements in the case of concrete polymer composites are obtained for compressive and tensile strengths. The progress in this field in United States and other countries is discussed in this rview. (M.S.)

  15. Proportioning of light weight concrete

    DEFF Research Database (Denmark)

    Palmus, Lars

    1996-01-01

    Development of a method to determine the proportions of the raw materials in light weight concrete made with leight expanded clay aggregate. The method is based on composite theory......Development of a method to determine the proportions of the raw materials in light weight concrete made with leight expanded clay aggregate. The method is based on composite theory...

  16. Revised Rules for Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Jensen, F. M.; Middleton, C.; Blackmore, A.

    This paper is based on research performed for the Highway Agency, London, UK under the project DPU/9/44 "Revision of Bridge Assessment Rules Based on Whole Life Performance: Concrete Bridges" It contains details of a methodology which can be used to generate Whole Life (WL) reliability profiles....... These WL reliability profiles may be used to establish revised rules for Concrete Bridges....

  17. Urban Experiments and Concrete Utopias

    DEFF Research Database (Denmark)

    Andersson, Lasse

    2009-01-01

    The paper explores how concrete urban experiments can challenge the pecuniary version of the experience city and stimulate a locally rooted and democratic version of an experience based city using heterotopias and concrete utopias as the link between top down planning and bottom up experiments in...

  18. Radiographic testing in concrete structures

    International Nuclear Information System (INIS)

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

  19. Concrete Masonry Designs: Educational Issue.

    Science.gov (United States)

    Hertzberg, Randi, Ed.

    2001-01-01

    This special journal issue addresses concrete masonry in educational facilities construction. The issue's feature articles are: (1) "It Takes a Village To Construct a Massachusetts Middle School," describing a middle school constructed almost entirely of concrete masonry and modeled after a typical small New England village; (2) "Lessons Learned,"…

  20. Structural lightweight concrete: recent research

    NARCIS (Netherlands)

    Walraven, J.; Den Uijl, J.; Stroband, J.; AI-ZubiN.; Gijsbers, J.; Naaktgeboren, M.

    1995-01-01

    As a result of a number of reasons new interest developed into the use of lightweight aggregate concrete. Within the scope of this development, a modernized code for lightweight concrete had to be written. In order to support this development, a number of research projects have been carried out. The

  1. Fatigue of Concrete Armour Units

    DEFF Research Database (Denmark)

    Sørensen, N. B.; Burcharth, H. F.; Liu, Z.

    1995-01-01

    In the present article fatigue as a possible reason for failure of Dolosse armour units made of plain concrete is discussed.......In the present article fatigue as a possible reason for failure of Dolosse armour units made of plain concrete is discussed....

  2. Technology Solutions Case Study: Insulating Concrete Forms

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2012-10-01

    This Pacific Northwest National Laboratory project investigated insulating concrete forms—rigid foam, hollow walls that are filled with concrete for highly insulated, hurricane-resistant construction.

  3. Study on healthcare magnetic concrete

    Institute of Scientific and Technical Information of China (English)

    YANG Yushan; DONG Faqin; FENG Jianjun

    2006-01-01

    Magnetic concrete was prepared by adding SrFe12O9 magnetic functional elementary material into concrete, and its magnetism was charged by magnetizing machine. The effect of SrFe12O9 content on magnetic field intensity and the attenuation of magnetic field intensity were investigated in different medium. The blood viscosity of rats kept in magnetic concrete was carried out. The results show that magnetic concrete can be prepared by adding SrFe12O9, and magnetic fields intensity increases with the augment of ferrite content. The attenuation of magnetic fields is mainly related with the density of medium, but it is secondary to the properties of medium. The blood viscosity of rats decreases under magnetic condition, but the blood cells remain the same as before. Experimental results support that magnetic concrete has great healthcare function.

  4. Basic principles of concrete structures

    CERN Document Server

    Gu, Xianglin; Zhou, Yong

    2016-01-01

    Based on the latest version of designing codes both for buildings and bridges (GB50010-2010 and JTG D62-2004), this book starts from steel and concrete materials, whose properties are very important to the mechanical behavior of concrete structural members. Step by step, analysis of reinforced and prestressed concrete members under basic loading types (tension, compression, flexure, shearing and torsion) and environmental actions are introduced. The characteristic of the book that distinguishes it from other textbooks on concrete structures is that more emphasis has been laid on the basic theories of reinforced concrete and the application of the basic theories in design of new structures and analysis of existing structures. Examples and problems in each chapter are carefully designed to cover every important knowledge point. As a basic course for undergraduates majoring in civil engineering, this course is different from either the previously learnt mechanics courses or the design courses to be learnt. Compa...

  5. Sodium concrete reaction: structural considerations

    International Nuclear Information System (INIS)

    An overview of the sodium concrete reaction phenomenon, with emphasis on structural considerations, is presented. Available test results for limestone, basalt, and magnetite concrete with various test article configurations are reviewed. Generally, tests indicate reaction is self limiting before all sodium is used. Uncertainties, however, concerning the mechanism for penetration of sodium into concrete have resulted in different theories about a reaction model. Structural behavior may be significant in the progression of the reaction due to thermal-structural-chemical interactions involving tensile cracking, compressive crushing, or general deterioration of concrete and the exposure of fresh concrete surfaces to react with sodium. Structural behavior of test articles and potential factors that could enhance the progression of the reaction are discussed

  6. Experimental and theoretical study of delayed ettringite damage in concrete

    Science.gov (United States)

    Ramadan, Elsaid Osman

    2000-12-01

    An experimental study is conducted to investigate the effect of a range of parameters on concrete expansion and premature deterioration associated with delayed ettringite formation (DEF). These parameters were identified from a comprehensive literature review; they include concrete curing conditions and cement chemistry. Specifically, the study investigated the effect of potassium and magnesium contents as well as the effect of water and steam curing conditions on concrete damage associated with DEF. An accelerated test method for DEF was evaluated and modifications are suggested. Concrete specimens were prepared with varying amounts of potassium and magnesium and subjected to different curing conditions. To accelerate any potential expansion, a beat cycle was employed. The change in length of the specimens was monitored for the duration of the study. Specimens were analyzed using the scanning electron microscope, x-ray dispersive analysis, and x-ray diffraction to determine the mechanism responsible for deterioration. Computed tomography x-ray was also employed as a non-destructive method for examining the internal crack patterns associated with expansion. The expansion data is fitted using the Kohnogorov-Avrami-Johenson-Mehl (KAJM) equation. This theory makes it possible to identify individual expansion processes and to identify the contribution of different expansion mechanisms. All concretes showed expansion following the beat cycle. Subjecting concrete to the heat cycle has a primary role in accelerating expansion. The age at which concrete is subjected to the beat cycle as well as the sample dimensions have a profound effect on the resulting expansion. The use of the concrete prisms as suggested in the modified test method offers a better alternative to cores suggested by Duggan. Increasing the potassium content has a deleterious effect on concrete expansion and premature deterioration and is also associated with dramatic reduction in compressive strength

  7. Non destructive Testing (NDT) of concrete containing hematite

    International Nuclear Information System (INIS)

    This paper described the results of Non-destructive ultrasonic and rebound hammer measurements on concrete containing hematite. Local hematite stones were used as aggregates to produce high density concrete for application in X-and gamma shielding. Concrete cube samples (150 mm x 150 mm x 150 mm) containing hematite as coarse aggregates were prepared by changing mix ratio, water to cement ratio (w/c) and types of fine aggregate. All samples were cured in water for 7 days and then tested after 28 days. Density, rebound number(N) and ultrasonic pulse velocity (UPV) of the samples were taken before compressed to failure. The measurement results are explained and discussed. (author)

  8. Physicochemical Study on the Interface Zone of Concrete Exposed to Different Sulfate Solutions

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper reports the results of the visual observations and micro-analysis of concrete core samples after 6 and 12 months of their exposure to sodium, ammonium and magnesium sulfate solutions with the same concentration of sulfate ions. XRD, SEM and EDS were used for micro-analysis of the microstructure and the composition of the interface zone in the samples. The results indicate that the deterioration of concrete by different sulfate solutions could proceed differently with regard to the mechanism and the mode of damage caused. The damage of concrete exposed to sodium sulfate solution is mainly caused by the gypsum crystals formed in the interface zone, which lead to expansion and cracking. In the case of concrete immersed in magnesium sulfate solutions, a layer of brucite (magnesium hydroxide) and gypsum was produced in the interface zone, which reduces the cohesiveness of the interface zone in concrete. For the concrete immersed in ammonium sulfate solutions, the conversation of mortar to some mush mass by ammonium ions and the formation of a large of gypsum occurred in the interface zone, consequently, serious softening of hydrated cement pastes and expansion and cracking of concrete are the characteristics of the attack by ammonium sulfate solutions. Also, it is considered that using drilled concrete core as samples to evaluate the sulfate resistance of concrete is a good and accelerated method.

  9. Influence of metakaolin on chemical resistance of concrete

    International Nuclear Information System (INIS)

    Nowadays the most suitable and widely used construction material is concrete. We could develop concrete for every request in connection with the properties of fresh concrete and the quality of hardened concrete, too. The demand is rising in application of special concretes, like high performance and ultra high performance concretes (HPC, UHPC). These are usable in extreme natural circumstances or in very corrosive surroundings (for example: sewage farm, sewer, cooling tower, biogas factories). The pH value of the commercial sewage is between 7–8, but this value is often around 4 or less. The concrete pipes, which transport the sewage, are under corrosion, because above the liquid level sulphuric acid occurs due to microbes. Acidic surroundings could start the corrosion of concrete. When the pH value reduces, the influence of the acids will increase. The most significant influence has the sulphuric acid. The pH value of sulphuric acid is about 1, or less. Earlier in the cooling towers of coal thermal power stations used special coating on the concrete wall. Recently application of high performance concrete without polymeric coating is more general. Cementitious supplementary materials are widely used to protect the concrete from these corrosive surroundings. Usually used cementitious supplementary materials are ground granulated blastfurnace slag (GGBS), flying ash (FA) or silica fume (SF). In the last years there has been a growing interest in the application of metakaolin. Metakaolin is made by heat treatment, calcinations of a natural clay mineral, kaolinite. In our present research the chemical resistance of mortars in different corrosive surroundings (pH=1 sulphuric acid; pH=3 acetic acid) and the chloride ion migration were studied on series of mortar samples using rapid chloride migration test. Cement paste and mortar samples were made with 17% metakaolin replacement or without metakaolin. The following cements were used: CEM II/A-S 42.5 N, CEM I 42.5 N

  10. Designing Concrete Of New Era:“Self Compacting Concrete

    Directory of Open Access Journals (Sweden)

    Dharmesh K. Bhagat

    2014-02-01

    Full Text Available In India, infrastructure is given prior importance and it is vision to make India fully developed up till 2020.But, it is a challenging job to produce high strength concrete and one of the problems for this is presence of air voids. At present to reduce these voids many compacting machines like vibrators are used in field. But, this leads to high noise pollution and annoyance the person working on site. Thus, to eliminate this problem related to compaction, strength and noise, a new concrete called Self Compacting Concrete [SCC] is used. It reduces the voids as it flows under its own weight. The strength and durability of SCC is much higher compared to conventional concrete. It also helps in achieving high quality of surface finishes and becomes sustainable as it saves the energy. But, the problem with this type of concrete is that there is no specific mix design for it. Thus, the aim of this research is to give proper methodology for the mix design of self compacting concrete and various points to be kept in mind while designing such flowable concrete.

  11. High performance polymer concrete

    Directory of Open Access Journals (Sweden)

    Frías, M.

    2007-06-01

    Full Text Available This paper studies the performance of concrete whose chief components are natural aggregate and an organic binder —a thermosetting polyester resin— denominated polymer concrete or PC. The material was examined macro- and microscopically and its basic physical and mechanical properties were determined using mercury porosimetry, scanning electron microscopy (SEM-EDAX, X-ray diffraction (XRD and strength tests (modulus of elasticity, stress-strain curves and ultimate strengths. According to the results of these experimental studies, the PC exhibited a low density (4.8%, closed pore system and a concomitantly continuous internal microstructure. This would at least partially explain its mechanical out-performance of traditional concrete, with average compressive and flexural strength values of 100 MPa and over 20 MPa, respectively. In the absence of standard criteria, the bending test was found to be a useful supplement to compressive strength tests for establishing PC strength classes.Este trabajo de investigación aborda el estudio de un hormigón de altas prestaciones, formado por áridos naturales y un aglomerante orgánico constituido por una resina termoestable poliéster, denominado hormigón polimérico HP. Se describe el material a nivel microscópico y macroscópico, presentando sus propiedades físicas y mecánicas fundamentales, mediante diferentes técnicas experimentales, tales como: porosimetría de mercurio, microscopía electrónica (SEM-EDAX, difracción de rayos X (DRX y ensayos mecánicos (módulo de elasticidad, curvas tensión- deformación y resistencias últimas. Como consecuencia del estudio experimental llevado a cabo, se ha podido apreciar cómo el HP está formado por porosidad cerrada del 4,8%, proporcionando una elevada continuidad a su microestructura interna, lo que justifica, en parte, la mejora de propiedades mecánicas respecto al hormigón tradicional, con unos valores medios de resistencia a compresión de 100

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

    OpenAIRE

    P. G. Anofriev

    2015-01-01

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

  13. Concrete Shrinkage Effect on the Composite Steel–Concrete State of Stresses

    OpenAIRE

    Moga, Petru; Alb, Claudia Pondichi

    2014-01-01

    The size of concrete shrinkage deformation depends, similar to creep, upon many factors: concrete composition, concrete quality, water/cement ratio, aggregate nature and grain size, compaction manner, humidity of ambient environment. In the steel–concrete composite structures, the phenomena of creep and shrinkage affect concrete behaviour and lead to shortening in the concrete slab. As concrete is rigidly tied to steel, the shortening is partially stopped and brings about a redistribution of ...

  14. Thermal Insulating Concrete Tiles

    Directory of Open Access Journals (Sweden)

    Sarkawt.A. Saeed

    2012-11-01

    Full Text Available This Paper studies the shape of high-thermal insulating concrete tiles used for roof tiling. The theoretical part consists of a comparison between this invented tiles and ordinary terrazzo tiles. The analysis depends on the values of thermal conductivity of the material used. The results showed that when these tiles are used for roof tiling, the temperature difference between the outside of roof surface and the inside room can be reduced about six times compared with the use of ordinary terrazzo tiles. In addition, these specimens were fabricated and tested for rupture and absorption tests. The test results showed that, they had a good resistance to the applied test loads, and high resistance to water absorption. The authors believe that, the results are remarkable, highly applicable and should be taken into consideration in building constructions.

  15. Effects of Elevated Temperature on Concrete with Recycled Coarse Aggregates

    Science.gov (United States)

    Salau, M. A.; Oseafiana, O. J.; Oyegoke, T. O.

    2015-11-01

    This paper discusses the effects of heating temperatures of 200°C, 400°C and 600°C each for 2 hours at a heating rate of 2.5°C/min on concrete with the content of Natural Coarse Aggregates (NCA) partially replaced with Recycled Coarse Aggregates (RCA), obtained from demolished building in the ratio of 0%, 15% and 30%.There was an initial drop in strength from 100°C to 200°C which is suspected to be due to the relatively weak interfacial bond between the RCA and the hardened paste within the concrete matrix;a gradual increase in strength continued from 200°C to 450°C and steady drop occurred again as it approached 600°C.With replacement proportion of 0%, 15% and 30% of NCA and exposure to peak temperature of 600°C, a relative concrete strength of 23.6MPa, 25.3MPa and 22.2MPa respectively can be achieved for 28 days curing age. Furthermore, RAC with 15% NCA replacement when exposed to optimum temperature of 450°C yielded high compressive strength comparable to that of control specimen (normal concrete). In addition, for all concrete samples only slight surface hairline cracks were noticed as the temperature approached 400°C. Thus, the RAC demonstrated behavior just like normal concrete and may be considered fit for structural use.

  16. Melt eruptions during molten corium concrete interactions

    Science.gov (United States)

    Robb, Kevin Richard

    The melt eruption phenomenon could occur during severe accidents at existing light water nuclear reactors. A postulated beyond-design basis accident includes the melting and relocation of the reactor core onto the concrete basemat of containment. The continually heated melt can reach high temperatures and thermally attack the underlying concrete, MCCI. As the melt cools, a crust forms on the upper surface of the melt pool. Melt eruptions occur when gases from the decomposing concrete passes through channels in the crust ejecting melt onto the upper surface of the crust. The impact of melt eruptions on the coolability of the melt is important when estimating the probability and timing of containment failure. This work focuses on understanding and modeling the melt eruption phenomenon. A model has been developed to predict the amount of melt ejected during melt eruptions. This entrainment model has been verified against an experimental database developed as part of this work. Several phenomena have been identified and modeled which may predict the creation and closure of eruptions sites. The models have been integrated into a MCCI systems code. The new melt eruption model predicted reasonable rates of melt ejection and the number and diameter of eruption sites for a sample simulation of a postulated reactor scale MCCI. Results from the new melt eruption model suggest an ex-vessel core melt under flooded conditions could readily quench.

  17. Utilization Possibility of Natural Aggregate Resources in Central Town of Tokat as Concrete Aggregate

    Directory of Open Access Journals (Sweden)

    S. I. Tutmaz

    2010-01-01

    Full Text Available In this study, aggregates of three quarries sampled from Tokat Province were tested to evaluate their suitability for concrete production. The aggregates were supplied from Yesilirmak River, and largely used in agricultural structures constructed in Tokat. Standard aggregate tests approved by Turkish Standards Institute were carried out to analyze the samples. Granulation, unit weight, specific weight, water absorption rate, resistance to frost, resistance against abrasion, ratio of fine materials, organic material contents and, mineralogical analysis of aggregates sampled from aggregate quarries were determined. Pressure resistance tests were conducted on concrete prepared by the aggregates. The results indicated that the aggregate granulation distribution of aggregate quarries evaluated was not suitable however other parameters determined were appropriate for concrete production. The resultant concrete had sufficient pressure resistance. The possible solutions to improve the improper characteristics of aggregates used in concrete were also determined and introduced with this study.

  18. Effect of Temperature and Age of Concrete on Strength – Porosity Relation

    Directory of Open Access Journals (Sweden)

    T. Zadražil

    2004-01-01

    Full Text Available The compressive strengths of unsealed samples of concrete at the age of 180 days and have been measured at temperatures 20 °C, 300 °C, 600 °C and 900 °C. All of tests were performed for cold material. We compared our results with those obtained in [10] for the same type of concrete (age 28, resp. 90 days and measured at temperature ranging from 20 °C to 280 °C. Dependencies of compressive strength and porosity were correlated together and compared for the samples of age 28, 90 and 180 days. Behaviour of concrete of the age 90, resp. 180 days confirms generally accepted hypothesis that with increasing porosity strength of the concrete decreases. It has to be stressed out, howerer, that concrete samples of the age 28 days exhibit totally opposite dependency. 

  19. Study of the Maya concrete

    International Nuclear Information System (INIS)

    The materials with which were constructed the buildings of the archaeological zone at the Maya culture were studied. Studies about the chemical composition of cement samples used in the construction of the Maya buildings were realized. The cement used was the same in all archaeological zones studied. The cement constituted the cementing matrix to obtain its derivatives: stuccos, mortars and, concretes. It was found that the Maya cement although has a variable chemical composition in its constitutive elements percentages, it is composed basically of calcite with fortuitous combinations of dolomite and clay materials, this last was founded in variable quantities from 0 % up to 10 % weight. The Maya cement was characterized as a variety of natural cement. The analysis and elemental chemical characterization was realized through the Scanning Electron Microscopy, X-ray diffraction and spectroscopic techniques. Therefore the microstructural characterization and the elemental chemical analysis were realized with a Scanning Electron microscope Phillips model XL30. The X-ray diffraction analysis was realized with a dust diffractometer Siemens D5000 operating at 30 KeV. The study of spectrograph was realized with an Emission spectrograph at 3 m focal distance model GX-1 Baird Atomic. (Author)

  20. Explosive demolition of activated concrete

    International Nuclear Information System (INIS)

    This paper describes the removal of a radiologically contaminated concrete pad. This pad was removed during 1979 by operating personnel under the direction of the Waste Management Program of EG and G Idaho, Inc. The concrete pad was the foundation for the Organic Moderated Reactor Experiment (OMRE) reactor vessel located at the Idaho National Engineering Laboratory (INEL). The pad consisted of a cylindrical concrete slab 15 ft in diameter, 2 ft thick, and reinforced with steel bar. It was poured directly onto basalt rocks approximately 20 ft below grade. The entire pad contained induced radioactivity and was therefore demolished, boxed, and buried rather than being decontaminated. The pad was demolished by explosive blasting

  1. Scale and size effects in dynamic fracture of concretes and rocks

    Science.gov (United States)

    Petrov, Y.; Selyutina, N.

    2015-09-01

    Structural-temporal approach based on the notion of incubation time is used for interpretation of strain-rate effects in the fracture process of concretes and rocks. It is established that temporal dependences of concretes and rocks are calculated by the incubation time criterion. Experimentally observed different relations between ultimate stresses of concrete and mortar in static and dynamic conditions are explained. It is obtained that compressive strength of mortar at a low strain rate is greater than that of concrete, but at a high strain rate the opposite is true. Influence of confinement pressure on the mechanism of dynamic strength for concretes and rocks is discussed. Both size effect and scale effect for concrete and rocks samples subjected to impact loading are analyzed. Statistical nature of a size effect contrasts to a scale effect that is related to the definition of a spatio-temporal representative volume determining the fracture event on the given scale level.

  2. Studying the Properties of Concrete Containing Natural Bio Productive EM1

    Directory of Open Access Journals (Sweden)

    Waleed Al Abed Raba

    2013-04-01

    Full Text Available  This study focused on the behavior of concrete when EM1 was added, to achieve the objective of this study a practical work was done on many concrete mixes. EM1 was added as weight percentage from cement weight (0%, 3%, 6.5%, 10%. The mixes was casted as cubic and cylinders samples and tested after 7, 14 and 28 days. Water cement ratio, compression strength, tensile strength, plastic index and wet density of hardened concrete were computed. The results shows that EM1 increases the workability of concrete compare with reference mixes so EM1 can used to increase the plastic of concrete and increase the compression and tensile and concrete density.

  3. Study of the fracture behavior of mortar and concretes with crushed rock or pebble aggregates

    Directory of Open Access Journals (Sweden)

    Sebastião Ribeiro

    2011-03-01

    Full Text Available The objective of this work was to compare the fracture energy of mortar and concretes produced with crushed rock and pebble aggregates using zero, 10, 20, 30 and 40% of aggregates mixed with standard mortar and applying the wedge splitting method to achieve stable crack propagation. The samples were cast in a special mold and cured for 28 days, after which they were subjected to crack propagation tests by the wedge splitting method to determine the fracture energies of the mortar and concrete. The concretes showed higher fracture energy than the mortar, and the concretes containing crushed rock showed higher resistance to crack propagation than all the compositions containing pebbles. The fracture energy varied from 38 to 55 J.m-2. A comparison of the number of aggregates that separated from the two concrete matrices with the highest fracture energies indicated that the concrete containing pebbles crumbled more easily and was therefore less resistant to crack propagation.

  4. Self healing phenomena in concretes and masonry mortars: A microscopic study

    NARCIS (Netherlands)

    Nijland, T.G.; Larbi, J.A.; Hees, R.P.J. van; Lubelli, B.A.; Rooij, M.R. de

    2007-01-01

    A microscopic survey of over 1000 of samples of concrete and masonry mortars from structures in the Netherlands shows that, in practice, self healing occurs in historic lime and lime – puzzolana mortars, in contrast to modern cement bound concretes and mortars. Self healing may be effected by the fo

  5. Review of concrete properties for prestressed concrete pressure vesssels

    International Nuclear Information System (INIS)

    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 1000C (2120F), 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

  6. Durability of fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place; Hansen, Kurt Kielsgaard

    The planned research will indicate, whether fibre reinforced concrete has better or worse durability than normal concrete. Durability specimens will be measured on cracked as well as uncracked specimens. Also the pore structure in the concrete will be characterized.Keywords: Fibre reinforced...... concrete, durability, pore structure, mechanical load...

  7. Betonreparationers holdbarhed (Durability of Concrete Repairs)

    DEFF Research Database (Denmark)

    Brimnes, Eydbjørn; Dali, Bogi í; Larsen, Erik Stoklund; Nielsen, Anders

    1999-01-01

    Concrete repairs on 11 pillars on bridges built in the sixties and repaired 8 to 9 years ago have been examined. Especially the chloride penetration in the repair concrete have been measured. Chloride penetration in the repair concrete is much lower than in the original concrete....

  8. Shear reinforced beams in autoclaved aerated concrete

    DEFF Research Database (Denmark)

    Cornelius, Thomas

    2010-01-01

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

  9. Leaching of concrete : experiments and modelling

    OpenAIRE

    Ekström, Tomas

    2001-01-01

    Many concrete dams, and other concrete structures within the hydropower industry are old and in a more or less severe state of degradation. Leaching is, together with freeze-thaw, the most common degradation problem in Swedish hydraulic concrete structures. This report contains a literature survey of concrete leaching, and presents the results of an experimental determination of leaching.

  10. Effect of Pelletized Coconut Fibre on the Compressive Strength of Foamed Concrete

    Directory of Open Access Journals (Sweden)

    Mohd Jaini Zainorizuan

    2016-01-01

    Full Text Available Foamed concrete is a controlled low density ranging from 400kg/m3 to 1800kg/m3, and hence suitable for the construction of buildings and infrastructures. The uniqueness of foamed concrete is does not use aggregates in order to retain low density. Foamed concrete contains only cement, sand, water and foam agent. Therefore, the consumption of cement is higher in producing a good quality and strength of foamed concrete. Without the present of aggregates, the compressive strength of foamed concrete can only achieve as high as 15MPa. Therefore, this study aims to introduce the pelletized coconut fibre aggregate to reduce the consumption of cement but able to enhance the compressive strength. In the experimental study, forty-five (45 cube samples of foamed concrete with density 1600kg/m3 were prepared with different volume fractions of pelletized coconut fibre aggregate. All cube samples were tested using the compression test to obtain compressive strength. The results showed that the compressive strength of foamed concrete containing 5%, 10%, 15% and 20% of pelletized coconut fibre aggregate are 9.6MPa, 11.4MPa, 14.6MPa and 13.4MPa respectively. It is in fact higher than the controlled foamed concrete that only achieves 9MPa. It is found that the pelletized coconut fibre aggregate indicates a good potential to enhance the compressive strength of foamed concrete.

  11. Study on Chloride Ion Penetration Resistance of Rubberized Concrete Under Steady State Condition

    Directory of Open Access Journals (Sweden)

    Md Noor Nurazuwa

    2016-01-01

    Full Text Available Foamed concrete is a controlled low density ranging from 400kg/m3 to 1800kg/m3, and hence suitable for the construction of buildings and infrastructures. The uniqueness of foamed concrete is does not use aggregates in order to retain low density. Foamed concrete contains only cement, sand, water and foam agent. Therefore, the consumption of cement is higher in producing a good quality and strength of foamed concrete. Without the present of aggregates, the compressive strength of foamed concrete can only achieve as high as 15MPa. Therefore, this study aims to introduce the pelletized coconut fibre aggregate to reduce the consumption of cement but able to enhance the compressive strength. In the experimental study, forty-five (45 cube samples of foamed concrete with density 1600kg/m3 were prepared with different volume fractions of pelletized coconut fibre aggregate. All cube samples were tested using the compression test to obtain compressive strength. The results showed that the compressive strength of foamed concrete containing 5%, 10%, 15% and 20% of pelletized coconut fibre aggregate are 9.6MPa, 11.4MPa, 14.6MPa and 13.4MPa respectively. It is in fact higher than the controlled foamed concrete that only achieves 9MPa. It is found that the pelletized coconut fibre aggregate indicates a good potential to enhance the compressive strength of foamed concrete.

  12. 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.

  13. Using of Local Limestone as Aggregate in Concrete Mixture

    Directory of Open Access Journals (Sweden)

    Dr.Muyasser M. Jomaa'h

    2012-03-01

    Full Text Available This research deals with the field investigations and construction properties for using limestone as a lightweight course aggregate in concrete mixture in stead of normal coarse aggregate. Concrete cubes samples have been prepared with dimensions of 150*150*150 mm according to ASTM. For these samples the normal coarse aggregate was replaced by 100% coarse crushed limestone. Three types of limestone which were used (Al-Sinea, Makhool and Himreen, it was found that the Al-Sinea type of limestone gave a good combination (fcu =32.11MPa without admixtures. The obtained results showed a suitable reduction in dead loads of structural elements and cost. Accordingly, the usage of limestone will improve the structural applications and concrete mix properties to attain economic viability. These above results make limestone as a good alternative of normal coarse aggregate

  14. Concrete density estimation by rebound hammer method

    Energy Technology Data Exchange (ETDEWEB)

    Ismail, Mohamad Pauzi bin, E-mail: pauzi@nm.gov.my; Masenwat, Noor Azreen bin; Sani, Suhairy bin; Mohd, Shukri [NDT Group, Nuclear Malaysia, Bangi, Kajang, Selangor (Malaysia); Jefri, Muhamad Hafizie Bin; Abdullah, Mahadzir Bin [Material Technology Program, Faculty of Applied Sciences, UiTM, Shah Alam, Selangor (Malaysia); Isa, Nasharuddin bin; Mahmud, Mohamad Haniza bin [Pusat Penyelidikan Mineral, Jabatan Mineral dan Geosains, Ipoh, Perak (Malaysia)

    2016-01-22

    Concrete is the most common and cheap material for radiation shielding. Compressive strength is the main parameter checked for determining concrete quality. However, for shielding purposes density is the parameter that needs to be considered. X- and -gamma radiations are effectively absorbed by a material with high atomic number and high density such as concrete. The high strength normally implies to higher density in concrete but this is not always true. This paper explains and discusses the correlation between rebound hammer testing and density for concrete containing hematite aggregates. A comparison is also made with normal concrete i.e. concrete containing crushed granite.

  15. Concrete density estimation by rebound hammer method

    International Nuclear Information System (INIS)

    Concrete is the most common and cheap material for radiation shielding. Compressive strength is the main parameter checked for determining concrete quality. However, for shielding purposes density is the parameter that needs to be considered. X- and -gamma radiations are effectively absorbed by a material with high atomic number and high density such as concrete. The high strength normally implies to higher density in concrete but this is not always true. This paper explains and discusses the correlation between rebound hammer testing and density for concrete containing hematite aggregates. A comparison is also made with normal concrete i.e. concrete containing crushed granite

  16. The Tectonic Potentials of Concrete

    DEFF Research Database (Denmark)

    Egholm Pedersen, Ole

    2013-01-01

    industrial paradigm of standardization, have been put forward. This development is carried forward by computers and digital fabrication, but has yet to find its way into the production of building components. With regards to concrete casting, however, existing research do offer advancement towards an...... increased customisation of casting moulds. The hypothesis of this research is that the techniques used in this research do not fully address the tectonic potentials of concrete which gives rise to the primary research question: Is it possible to enhance existing or develop new concrete casting techniques...... which allows for individualisation and resource optimisation, while matching or enhancing the tectonic potentials found in existing, repetitive concrete casting techniques? The research is comprised of two modes of inquiry: an empirical study of contemporary casting methods and subsequently six case...

  17. Nondestructive testing of concrete structures

    International Nuclear Information System (INIS)

    Nondestructive testing of concrete is highly inhomogeneous which makes it cumbersome to setup experimental procedures and analyze experimental data. However, recent research and development activities have discovered the different methods of NDT, like the electromagnetic method, ultrasonic pulse velocity test, pulse echo/impact echo test, infrared thermography, radar or short pulse radar techniques, neutron and gamma radiometry, radiography, carbonation test and half-cell potential method available for NDT of concrete structures. NDT of concrete is emerging as a useful tool for quality control and assurance. This papers also describes the more common NDT methods discussed during the two-week course on 'Nondestructive Testing of Concrete Structures', held at the Malaysian Institute for Nuclear Technology Research (MINT) in Malaysia, which was jointly organized by MINT and the International Atomic Energy Agency (IAEA)

  18. Contaminated concrete surface layer removal

    International Nuclear Information System (INIS)

    Equipment is being developed to economically remove contaminated concrete surfaces in nuclear facilities. To be effective this equipment should minimize personnel radiation exposure, minimize the volume of material removed, and perform the operation quickly with the least amount of energy. Several methods for removing concrete surfaces are evaluated for use in decontaminating such facilities. Two unique methods especially suited for decontamination are described: one, the water cannon, is a device that fires a high-velocity jet of fluid causing spallation of the concrete surface; the other, a concrete spaller, is a tool that exerts radial pressure agains the sides of a pre-dilled shallow cylindrical hole causing spallation to occur. Each method includes a means for containing airborne contamination. Results of tests show that these techniques can rapidly and economically remove surfaces, and leave minimal rubble for controlled disposal

  19. Electrically conductive polymer concrete overlays

    Science.gov (United States)

    Fontana, J. J.; Webster, R. P.

    1984-08-01

    The use of cathodic protection to prevent the corrosion of reinforcing steel in concrete structures has been well established. Application of a durable, skid-resistant electrically conductive polymer concrete overlay would advance the use of cathodic protection for the highway industry. Laboratory studies indicate that electrically conductive polymer concrete overlays using conductive fillers, such as calcined coke breeze, in conjunction with polyester or vinyl ester resins have resistivities of 1 to 10 ohm-cm. Both multiple-layer and premixed mortar-type overlays were made. Shear bond strengths of the conductive overlays to concrete substrates vary from 600 to 1300 psi, with the premixed overlays having bond strengths 50 to 100% higher than the multiple-layer overlays.

  20. 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......Scholars emphasize the cognitive or ideational aspects of institutional logics. Less clear is the role of materiality, which is a key aspect of institutional logics, and aesthetic responses to material objects. This study focuses on the introduction of a new building material—concrete— during 1890...... to 1939 in the architectural profession. Our findings reveal that how professional logics were enacted drove different process for incorporating concrete as a legitimate building material: in France professional and state logics combined to create regulations that governed architects’ use of concrete...

  1. The behaviour of concrete structures in fire

    OpenAIRE

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

    2007-01-01

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

  2. A Research About the Concrete Compression Failure

    OpenAIRE

    Deliang Meng; Huijian Li; Lixin Zhang; Pin Cheng

    2013-01-01

    Concrete material is one of the wide applications materials in the engineering. There is an important implication on national life safety to research its destruction. And size effect of the concrete also has an important impact on failure mechanism and strain injury of the concrete. There are many influencing factors on concrete size effect. In this paper, we will use the numerical simulation method to research the concrete compression failure from two aspects. One is the arrangement of th...

  3. Metrology Needs for Predicting Concrete Pumpability

    OpenAIRE

    Myoungsung Choi; Ferraris, Chiara F.; Martys, Nicos S.; Didier Lootens; Bui, K.; H. R. Trey Hamilton

    2015-01-01

    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 tec...

  4. Analysis of concrete slabs supported on soil

    OpenAIRE

    Barros, Joaquim A. O.

    1999-01-01

    A numerical model for material non-linear analysis of concrete slabs supported on soil is described in this work. In this model, the cracked concrete is regarded as cracks with concrete between cracks. The behaviour of the concrete between cracks is simulated by the conventional theory of plasticity. The behaviour of the cracks is defined by their constitutive laws using the concrete fracture properties. Smeared multifixed and rotating crack models are available in the model. ...

  5. Development of concrete shrinkage performance specifications

    OpenAIRE

    Mokarem, David W.; Meyerson, Richard M.; Weyers, Richard E.

    2003-01-01

    During its service life, concrete undergoes volume changes. One of the types of deformation is shrinkage. The four main types of shrinkage associated with concrete are plastic, autogenous, carbonation, and drying shrinkage. The volume changes in concrete due to shrinkage can lead to the cracking of the concrete. In the case of reinforced concrete, the cracking may produce a direct path for chloride ions to reach the reinforcing steel. Once chloride ions reach the steel surface, the steel will...

  6. Concrete production analysis for hydrotechnical structure

    OpenAIRE

    Zupančič, Jože

    2009-01-01

    The thesis deals with the production of concrete in the concrete mixing plant HB 2000 and the project of construction of hydroelectric power plant Krško. In the first stage, the thesis offers a general description of different types of concrete mixing plants and a manner of verification of production abilities of concrete mixing plants in Slovenija for assuring quality where control examinations play one of the essential parts in preventive measures at assuring quality concrete mixes. It also...

  7. EFFECT OF CHANGE AT THE AMBIENT TEMPERATURE ON MECHANICAL PROPERTIES OF CONCRETE

    OpenAIRE

    Oğuzhan KELEŞTEMUR

    2009-01-01

    In this study, the effects of the ambient temperature on the mechanical properties of the concrete have been investigated. For this purpose, the concrete samples which were kept in cure tank which has 20±2 oC temperature during 28 days, after the cure period all the samples were kept for dry in laboratory environment for 24 hours. Then the concrete samples were waited in different temperatures which are -30, -20, -10, 0, 10, 20, 30, 40 and 50ºC during 24 hours. Afterwards compressive strength...

  8. Measurement of lime/silica ratio in concrete using PGNAA technique

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)]. E-mail: aanaqvi@kfupm.edu.sa; Nagadi, M.M. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Al-Amoudi, O.S.B. [Department of Civil Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

    2005-12-01

    Prompt gamma neutron activation analysis (PGNAA) technique has been used to determine lime/silica ratio in concrete samples using an accelerator-based PGNAA facility. The ratio was determined from the measured yield of 6.42 MeV prompt {gamma}-rays of calcium and 4.93 MeV {gamma}-rays of silicon from the six concrete samples. The experimental results were compared with the results of the Monte Carlo simulations. An excellent agreement has been achieved between the two. The study has demonstrated successful use of the accelerator-based PGNAA setup in non-destructive analysis of the concrete samples.

  9. Measurement of lime/silica ratio in concrete using PGNAA technique

    International Nuclear Information System (INIS)

    Prompt gamma neutron activation analysis (PGNAA) technique has been used to determine lime/silica ratio in concrete samples using an accelerator-based PGNAA facility. The ratio was determined from the measured yield of 6.42 MeV prompt γ-rays of calcium and 4.93 MeV γ-rays of silicon from the six concrete samples. The experimental results were compared with the results of the Monte Carlo simulations. An excellent agreement has been achieved between the two. The study has demonstrated successful use of the accelerator-based PGNAA setup in non-destructive analysis of the concrete samples

  10. Measurement of lime/silica ratio in concrete using PGNAA technique

    Science.gov (United States)

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

    2005-12-01

    Prompt gamma neutron activation analysis (PGNAA) technique has been used to determine lime/silica ratio in concrete samples using an accelerator-based PGNAA facility. The ratio was determined from the measured yield of 6.42 MeV prompt γ-rays of calcium and 4.93 MeV γ-rays of silicon from the six concrete samples. The experimental results were compared with the results of the Monte Carlo simulations. An excellent agreement has been achieved between the two. The study has demonstrated successful use of the accelerator-based PGNAA setup in non-destructive analysis of the concrete samples.

  11. Digital laminography assessment of the damage in concrete exposed to freezing temperatures

    KAUST Repository

    Wakimoto, Kentaro

    2008-10-01

    The research explores the possibility of using digital laminography as a non-destructive inspection X-ray method to image the damage existing in concrete exposed to low temperatures. Freezing-thawing and scaling tests were performed and digital laminography was used to determine the degree of damage existing inside the concrete samples. First, digital laminography was performed on the concrete sample and then a visual inspection was done by slicing the sample after it was vacuum-impregnated with epoxy in order to compare the differences in crack width. © 2008 Elsevier Ltd. All rights reserved.

  12. Sustainable Concrete with Recycled Aggregate

    OpenAIRE

    Kara, P

    2012-01-01

    Concretes produced with recycled aggregates are the subject of several papers recently published in the technical literature. Substitution of natural aggregates can be one of possibilities to take care of landfills and increase of CO2 emissions into the atmosphere in Latvia. Recycled aggregate is a valuable resource; value-added consumption of recycled aggregate, as replacement for virgin aggregate in concrete, can yield significant energy and environmental benefits. In present study recycled...

  13. Environmentally friendly, customised sprayed concrete

    OpenAIRE

    Río, Olga

    2010-01-01

    The quality of structural shotcrete or sprayed concrete depends not only on the Same factors as conventional structural concrete, but also on other placement-related issues such as pumping or spraying. Although today's primarily prescriptive design and control tools guarantee quality to some extent, the results are uncertain and mix design procedures do not provide sound information, a priori", on mechanical properties or durabllity. Nor does this approach contribute to design or produce spra...

  14. Mechanical behaviour of adhesive joints such as a concrete epoxy

    OpenAIRE

    Aguiar, J. L. Barroso de; Reymond, M. C.; Paillère, A. M.

    1987-01-01

    The sample DCB is separated in two parts then sticked by epoxy to study adhesion between concrete and epoxy resin. The crack propagation was initiated at a notch in a double cantilever beam. The notch of the test sample was opened by an Instron tensile machin. The crack extension was followed through direct optical observations. The displacement was measured by an extensometer. During the fracture test, mechanical behaviour of the sample was monitored with various techniques: the experimental...

  15. Prediction of concrete compression strength using ultrasonic pulse velocity

    Science.gov (United States)

    Azreen, M. N.; Pauzi, I. M.; Nasharuddin, I.; Haniza, M. M.; Akasyah, J.; Karsono, A. D.; Lei, V. Yen

    2016-01-01

    The relationship of ultrasonic stress waves transmitted along direct and indirect paths in concrete samples was investigated. Tests were conducted on plain concrete slabs from different grades of 15, 25, 30, 40 and Ultrahigh Performance Concrete that have dimensions of 750mm x 150mm x 150 mm. Direct ultrasonic pulse velocity tests were conducted between the top and the bottom surfaces of the concrete samples and indirect tests were conducted along the surface. A test procedure to determine indirect wave velocities was refined by defining the spacing of the transducers which are 50, 100, 150, 200, 250, 300, 350, 400, 450 mm. The correlation was established between direct and indirect UPV measurements via statistical analysis. From the analysis, it can be concluded that direct UPV has higher value than indirect UPV value by 16.5 % due to position of transducers. The compression strength of the concretes was studied to be compared with the direct and indirect transmission, with direct transmission method showed a good correlation with compression strength.

  16. Chemo-mechanical coupling behaviour of leached concrete

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, V.H. [Laboratoire d' Analyse des Materiaux et Identification, Ecole Nationale des Ponts et Chaussees, Institut Navier, 6 et 8, Avenue Blaise Pascal, 77455 Marne la Vallee Cedex 2 (France); Colina, H. [ATILH, 7, Place de la Defense, 92974 Paris-La-Defense Cedex (France); Torrenti, J.M. [LCPC Paris, 58, Boulevard Lefebvre 75732 Paris Cedex 15 (France); LMT, ENS Cachan, 61, Avenue du President Wilson, 94235 Cachan (France)], E-mail: jean-michel.torrenti@ponts.org; Boulay, C. [LCPC Paris, 58, Boulevard Lefebvre 75732 Paris Cedex 15 (France); Nedjar, B. [Laboratoire d' Analyse des Materiaux et Identification, Ecole Nationale des Ponts et Chaussees, Institut Navier, 6 et 8, Avenue Blaise Pascal, 77455 Marne la Vallee Cedex 2 (France)

    2007-11-15

    This paper deals with concrete behaviour under chemical and mechanical degradations. Experimental investigations are described where the effects of the calcium leaching process of concrete on its mechanical properties are highlighted. The calcium leaching and mechanical tests on cement paste, mortar and concrete samples are presented. Because of the slow kinetics of leaching under deionised water, an accelerated method has been chosen by using an ammonium nitrate solution instead. The specimens are immersed into a 6 mol/l ammonium nitrate solution with a controlled pH disposal. To quantify the leaching evolution, the degradation depth is then measured at certain time intervals by means of a phenolphthalein solution. The experimental results show the chemical degradation of the cement-based material and the important role of aggregate in the calcium leaching process of concrete. Compression tests of concrete samples are also performed. We observe that there is a strong coupling between the calcium leaching and the mechanical behaviour; as leaching grows, a loss of stiffness and of strength are observed and a smoother post-peak behaviour is noted.

  17. Nondestructive detection and characterization of carbonation in concrete

    International Nuclear Information System (INIS)

    Exposure of concrete to the environment leads to changes in composition, microstructure, and properties; these effects often start from the surface of a concrete structure. A specific, widespread environmental effect is carbonation, where carbon dioxide penetrates the surface of concrete and reacts with calcium hydroxide that is a product of Portland cement hydration in concrete. Carbonation is of interest not only because it can lead to the initiation of reinforcement corrosion, but also carbon is increasingly used during curing to alter the surface properties of cement-based materials as a method to 'sink' carbon in cement-based materials. Nonlinear Rayleigh surface wave measurements are performed on uncarbonated and carbonated concrete samples to assess any mechanical changes induced by carbonation,. In order to minimize the effects of contact conditions, the generated signals are detected by a noncontact air-coupled transducer (100 kHz) at locations along the propagation axis. The nonlinearity parameter, β is used to quantitatively characterize the degree of carbonation. To more accurately analyze the data, corrections are made for the effects of attenuation and diffraction. A comparison between the carbonated and uncarbonated samples demonstrates that pores and micro-cracks are affected by the carbonation product and these significantly change the measured nonlinearity parameter

  18. Concrete waste reduction of 50%

    International Nuclear Information System (INIS)

    During decommissioning quite a volume of concrete waste is produced. The degree of activation of the waste can range from clearly activated material to slightly activated or contaminated concrete. The degree of activation influences the applicable waste management processes that can be applied. The subsequent waste management processes can be identified for concrete waste are; disposal, segregation, re-use, conditional release and release. With each of these steps, the footprint of radioactive decommissioning waste is reduced. Future developments for concrete waste reduction can be achieved by applying smart materials in new build facilities (i.e. fast decaying materials). NRG (Nuclear Research and consultancy Group) has investigated distinctive waste management processes to reduce the foot-print of concrete waste streams resulting from decommissioning. We have investigated which processes can be applied in the Netherlands, both under current legislation and with small changes in legislation. We have also investigated the separation process in more detail. Pilot tests with a newly patented process have been started in 2015. We expect that our separation methods will reduce the footprint reduction of concrete waste by approximately 50% due to release or re-use in the nuclear sector or in the conventional industry. (authors)

  19. Nonlinear acoustic nondestructive testing for concrete durability

    Science.gov (United States)

    Wu, Hwai-Chung; Warnemuende, Kraig

    2000-06-01

    Several nondestructive testing methods can be used to determine the damage in a concrete structure. Linear ultrasonic techniques, e.g. pulse-velocity and amplitude attenuation, are very common in nondestructive evaluation. Velocity of propagation is not very sensitive to the degrees of damage unless a great deal of micro-damage having evolving into localized macro-damage. This transition typically takes place around 80% of the ultimate compressive strength. Amplitude attenuation is potentially more sensitive than pulse-velocity. However, this method depends strongly on the coupling conditions between transducers and concrete, hence unreliable. A baseline test of the linear acoustics of several mortar samples was conducted. These mortar samples have been previously damaged to different levels. Several other testing methods were also performed on the same samples to form a comparison. The focus is in comparing the sensitivity of a new testing method (Non-linear Acoustic NDE) with several more traditional testing methods. Non-linearity of the material stiffness is expressed in non-linear acoustics as the effect that damage and flaws have on the modulation of a signal as it propagates through the material. Spectral (non-linear) analysis is much more sensitive to lower damage states and less dependent on the repeatability of the coupling of the transducers.

  20. Evaluation of the Concrete Contribution Factor for Composite Sections with Lightweight Concrete under Axial Compression

    OpenAIRE

    Yasser M. Hunaiti; Nabil M. Falah; Issam M. Assi

    2002-01-01

    Tests on hollow steel tubes of square, rectangular and circular sections filled with foamed concrete and lightweight aggregate concrete were conducted to investigate the contribution of these concretes to the strength of cross sections of composite short columns. In addition, these tests aims at understanding the behavior of short columns with lightweight concrete. Thirty short column specimens filled with foamed concrete and lightweight aggregate concrete were tested in this investigation. F...

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

    OpenAIRE

    K. Srinivasa Rao

    2013-01-01

    Concrete elements exposed to fire undergo temperature gradients and as a result, undergo physical changes or spalling which leads to expose steel reinforcement. This causes distress in concrete structures. The performance of concrete can be improved with the addition of steel fibres to concrete especially when it is exposed to heat. Therefore, this study has been carried out to generate experimental data on standard concrete ofgrade M45 and Fiber Reinforced Standard Concrete exposed to elevat...

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

    OpenAIRE

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

    2016-01-01

    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...

  3. Natural aggregate totally replacement by mechanically treated concrete waste

    Directory of Open Access Journals (Sweden)

    Junak Jozef

    2015-06-01

    Full Text Available This paper presents the results obtained from the research focused on the utilization of crushed concrete waste aggregates as a partial or full replacement of 4/8 and 8/16 mm natural aggregates fraction in concrete strength class C 16/20. Main concrete characteristics such as workability, density and compressive strength were studied. Compressive strength testing intervals for samples with recycled concrete aggregates were 2, 7, 14 and 28 days. The amount of water in the mixtures was indicative. For mixture resulting consistency required slump grade S3 was followed. Average density of all samples is in the range of 2250 kg/m3 to 2350 kg/m3. The highest compressive strength after 28 days of curing, 34.68 MPa, reached sample, which contained 100% of recycled material in 4/8 mm fraction and 60% of recycled aggregates in 8/16 mm fraction. This achieved value was only slightly different from the compressive strength 34.41 MPa of the reference sample.

  4. Gamma ray and neutron shielding properties of some concrete materials

    International Nuclear Information System (INIS)

    Highlights: → This study sheds light on the shielding properties of gamma-rays and neutrons for some concrete samples. → The experimental mass attenuation coefficients values were compared with theoretical values obtained using WinXCom. → Moreover, neutron shielding has been treated in terms of macroscopic removal cross-section (ΣR, cm-1) concept. → The NXcom program was employed to calculate the attenuation coefficients values of neutrons. → These values showed a change with energy and composition of the concrete samples. - Abstract: Shielding of gamma-rays and neutrons by 12 concrete samples with and without mineral additives has been studied. The total mass attenuation and linear attenuation coefficients, half-value thicknesses, effective atomic numbers, effective electron densities and atomic cross-sections at photons energies of 59.5 and 661 keV have been measured and calculated. The measured and calculated values were compared and a reasonable agreement has been observed. Also the recorded values showed a change with energy and composition of the concrete samples. In addition, neutron shielding has been treated in terms of macroscopic removal cross-section (ΣR, cm-1) concept. The WinXCom and NXcom programs were employed to calculate the attenuation coefficients of gamma-rays and neutrons, respectively.

  5. Retrofitting Of Reinforced Concrete Column by Steel Jacketing

    Directory of Open Access Journals (Sweden)

    Abhishek Jodawat

    2016-07-01

    Full Text Available Reinforced concrete structures often require strengthening to increase their capacity to sustain additional loads, due to change in use that resulted in additional live loads, deterioration of the load carrying elements, design errors, construction problems during erection, aging of structure itself or upgrading to confirm to current code requirements. These situations may require additional concrete elements or the entire concrete structure to be strengthened, repaired or retrofitted. Common methods for strengthening columns include concrete jacketing, fiber reinforced polymer (FRP jacketing and steel jacketing. All these methods have been shown to effectively increase the axial load capacity of columns. The experimental study was carried out on RC column on designed and detailed using IS 456:2000 provisions. The concrete mix design being performed after conducting numerous material test and cube test to validate expected strength as per specified grade of concrete. The trial testing conducted to estimate load at 1st crack and failure load for normal RC column with capturing displacement using dial gauges at regular load increment in UTM. The loading conditions are decided based on failure load to induce cracks in column under 85% loading of the failure one. In all fifteen specimen casted and tested with three samples for failure load estimation, three samples each for plate jacketing & angle battening system and three samples each for plate jacketing & angle battening with column preloaded to 85% of its failure load. The angle batten system proves to be better compared to full plate retrofitting in terms of load carrying capacity and enhancing confinement effect.

  6. Drying of concrete. Part II: The drying time of concrete structures

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard; Christensen, Søren Lolk

    1998-01-01

    The composition of a concrete mix has a significant influence on the drying time to reach a given relative humidity in the concrete pores. Knowledge of the influence on the drying of a specific component in the concrete makes it possible to design a concrete mix having a predetermined drying time....... In the paper the effects of the air content and the silica fume content on the drying time are investigated on two concrete mixes having different water/cement ratios. One concrete represents a normal concrete and the other represents a selfdesiccation concrete....

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

    Science.gov (United States)

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

    2014-04-01

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

  8. Strengthening Reinforced Concrete Beams with CFRP and GFRP

    OpenAIRE

    Mehmet Mustafa Önal

    2014-01-01

    Concrete beams were strengthened by wrapping the shear edges of the beams twice at 45° in opposite directions by either carbon fiber reinforced polymer (CFRP) or glass fiber reinforced polymer (GFRP). The study included 3 CFRP wrapped beams, 3 GFRP wrapped beams, and 3 control beams, all of which were 150 × 250 × 2200 mm and manufactured with C20 concrete and S420a structural steel at the Gazi University Technical Education Faculty labs, Turkey. Samples in molds were cured by watering in the ...

  9. Comparative Analysis of Measured and Predicted Shrinkage Strain in Concrete

    Directory of Open Access Journals (Sweden)

    Kossakowski P. G.

    2014-06-01

    Full Text Available The article discusses the issues related to concrete shrinkage. The basic information on the phenomenon is presented as well as the factors that determine the contraction are pointed out and the stages of the process are described. The guidance for estimating the shrinkage strain is given according to Eurocode standard PN-EN 1992-1-1:2008. The results of studies of the samples shrinkage strain of concrete C25/30 are presented with a comparative analysis of the results estimated by the guidelines of the standard according to PN-EN 1992-1- 1:2008

  10. Numerical simulations of concrete flow: A benchmark comparison

    DEFF Research Database (Denmark)

    Roussel, Nicolas; Gram, Annika; Cremonesi, Massimiliano; Ferrara, Liberato; Krenzer, Knut; Mechtcherine, Viktor; Shyshko, Sergiy; Skocec, Jan; Spangenberg, Jon; Svec, Oldrich; Thrane, Lars Nyholm; Vasilic, Ksenija

    2016-01-01

    First, we define in this paper two benchmark flows readily usable by anyone calibrating a numerical tool for concrete flow prediction. Such benchmark flows shall allow anyone to check the validity of their computational tools no matter the numerical methods and parameters they choose. Second, we...... compare numerical predictions of the concrete sample final shape for these two benchmark flows obtained by various research teams around the world using various numerical techniques. Our results show that all numerical techniques compared here give very similar results suggesting that numerical...

  11. Comparative Analysis of Measured and Predicted Shrinkage Strain in Concrete

    OpenAIRE

    Kossakowski P. G.; Raczkiewicz W.

    2014-01-01

    The article discusses the issues related to concrete shrinkage. The basic information on the phenomenon is presented as well as the factors that determine the contraction are pointed out and the stages of the process are described. The guidance for estimating the shrinkage strain is given according to Eurocode standard PN-EN 1992-1-1:2008. The results of studies of the samples shrinkage strain of concrete C25/30 are presented with a comparative analysis of the results estimated by the guideli...

  12. Nanogranular origin of concrete creep.

    Science.gov (United States)

    Vandamme, Matthieu; Ulm, Franz-Josef

    2009-06-30

    Concrete, the solid that forms at room temperature from mixing Portland cement with water, sand, and aggregates, suffers from time-dependent deformation under load. This creep occurs at a rate that deteriorates the durability and truncates the lifespan of concrete structures. However, despite decades of research, the origin of concrete creep remains unknown. Here, we measure the in situ creep behavior of calcium-silicate-hydrates (C-S-H), the nano-meter sized particles that form the fundamental building block of Portland cement concrete. We show that C-S-H exhibits a logarithmic creep that depends only on the packing of 3 structurally distinct but compositionally similar C-S-H forms: low density, high density, ultra-high density. We demonstrate that the creep rate ( approximately 1/t) is likely due to the rearrangement of nanoscale particles around limit packing densities following the free-volume dynamics theory of granular physics. These findings could lead to a new basis for nanoengineering concrete materials and structures with minimal creep rates monitored by packing density distributions of nanoscale particles, and predicted by nanoscale creep measurements in some minute time, which are as exact as macroscopic creep tests carried out over years. PMID:19541652

  13. 304 Concretion facility closure plan

    International Nuclear Information System (INIS)

    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

  14. Carbonation-Related Microstructural Changesin Long-Term Durability Concrete

    Directory of Open Access Journals (Sweden)

    Cláudio A. Rigo da Silva

    2002-09-01

    Full Text Available This paper discusses the effects of carbonation on the microstructure of Portland cement concrete for long-term durability applications. A class C40 concrete (characteristic compression strength between 40 MPa and 44 MPa on the 28th day, according to Brazilian standard NBR 8953 was chosen for the experimental study of the carbonation effects, from which test samples were molded for accelerated test under a 100%-CO2 atmosphere after physical and mechanical characterization. It was observed that carbonation provoked a reduction of 5% to 12% of the concrete open porosity accessible to water. Flexural strength values obtained after the carbonation tests revealed a decrease of 12% and 25% in relation to the values obtained before tests on the 28th and 91st days, respectively.

  15. Failure analysis of an Oregon coast reinforced concrete bridge

    Energy Technology Data Exchange (ETDEWEB)

    Holcomb, Gordon R.; Covino, Bernard S., Jr.; Cramer, Stephen D.; Bullard, Sophie J.; Russell, James H.; Soltesz, S.M. (Oregon Dept. of Transportation; Laylor, H.M. (Oregon Dept. of Transportation)

    2001-01-01

    The coastal highway along the Oregon coast contains many reinforced concrete bridges constructed between 1925 and 1955. Chloride-induced corrosion resulted in the need for the rehabilitation or replacement of a number of these bridges. A failure analysis of the Rocky Point Viaduct (built in 1954, patched in 1969, replaced in 1994) is presented. Analysis included powder sampling and profiling of Cl concentration, determining the permeable void fraction in the concrete, and measuring rebar half cell potentials. Insufficient concrete cover over the shear stirrups was the major factor in the premature failure of the Viaduct. The time required for corrosion initiation and cracking was modeled by calculating diffusion parameters (surface Cl concentration (Co) and diffusion coefficient (D)) from Cl profiles. The model was used to examine the relative ineffectiveness of the patch repairs by showing increased Cl transport in the patch due to both higher Co and D values.

  16. Porosity and Mechanical Strength of an Autoclaved Clayey Cellular Concrete

    Directory of Open Access Journals (Sweden)

    P. O. Guglielmi

    2010-01-01

    Full Text Available This paper investigates the porosity and the mechanical strength of an Autoclaved Clayey Cellular Concrete (ACCC with the binder produced with 75 wt% kaolinite clay and 25 wt% Portland cement. Aluminum powder was used as foaming agent, from 0.2 wt% to 0.8 wt%, producing specimens with different porosities. The results show that the specimens with higher content of aluminum presented pore coalescence, which can explain the lower porosity of these samples. The porosities obtained with the aluminum contents used in the study were high (approximately 80%, what accounts for the low mechanical strength of the investigated cellular concretes (maximum of 0.62 MPa. Nevertheless, comparing the results obtained in this study to the ones for low temperature clayey aerated concrete with similar compositions, it can be observed that autoclaving is effective for increasing the material mechanical strength.

  17. Leachability of dissolved chromium in asphalt and concrete surfacing materials.

    Science.gov (United States)

    Kayhanian, Masoud; Vichare, Akshay; Green, Peter G; Harvey, John

    2009-08-01

    Leachate metal pollutant concentrations produced from different asphalt and concrete pavement surfacing materials were measured under controlled laboratory conditions. The results showed that, in general, the concentrations of most metal pollutants were below the reporting limits. However, dissolved chromium was detected in leachate from concrete (but not asphalt) specimens and more strongly in the early-time leachate samples. As the leaching continued, the concentration of Cr decreased to below or close to the reporting limit. The source of the chromium in concrete pavement was found to be cement. The concentration of total Cr produced from leachate of different cement coming from different sources that was purchased from retail distributors ranged from 124 to 641mug/L. This result indicates that the potential leachability of dissolved Cr from concrete pavement materials can be reduced through source control. The results also showed that the leachability of dissolved Cr in hardened pavement materials was substantially reduced. For example, the concentration of dissolved Cr measured in actual highway runoff was found to be much lower than the Cr concentration produced from leachate of both open and dense graded concrete pavement specimens under controlled laboratory study. It was concluded that pavement materials are not the source of pollutants of concern in roadway runoff; rather most pollutants in roadway surface runoff are generated from other road-use or land-use sources, or from (wet or dry) atmospheric deposition. PMID:19604624

  18. Additives as corrosion inhibitors in reinforced concrete

    International Nuclear Information System (INIS)

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

  19. Analysis of Comparison between Unconfined and Confined Condition of Foamed Concrete Under Uni-Axial Compressive Load

    Directory of Open Access Journals (Sweden)

    Mohd Zairul A. Abdul Rahman

    2010-01-01

    Full Text Available Problem statement: Foamed concrete has become most commercial material in construction industry. People in industries were come out with the new mix design of foamed concrete to meet the specification and the requirements needed. Approach: This is because foamed concrete has the possibility as alternative of lightweight concrete for producing intermediate strength capabilities with excellent thermal insulation, freeze-thaw resistance, high-impact resistance and good shock absorption. Results: Currently Standard test to measure the compressive strength of foamed concrete is using standard unconfined compressive test. Several research has been conduct but the compressive strength using standard unconfined compressive test not capture true behavior of foamed concrete because it just achieved only low compressive strength and sample under compression failed due to brittle collapse of the sample. This paper was analyses the comparison between standard compressive test and confined compressive test. The confinement test introduced to prevent sample from brittle collapse. Foamed concrete cylindrical sample has been investigated under the standard compressive test for hard concrete (ASTM-C39. Based on the research, samples are produced under unconfined and confined condition. Analysis has been done and the result show that under standard compressive test, the sample failed due to early crack initiation and failed. Confinement condition was increase the compressive strength but this condition influence the result. Conclusion/Recommendations: Standard test is not suitable to capture the true behavior of foamed concrete, and to prevent the sample from brittle collapse during the test, new testing method was introduced to capture the true behavior of foamed concrete which is using Quasi Static Indentation Test. This test can be used to study about the behaviour of foamed concrete before it can be implemented to its final application.

  20. Combined Non-destructive Testing (NDT) methods for evaluating concrete quality

    International Nuclear Information System (INIS)

    This paper described the results of combining Non-destructive measurements on concrete. Local crushed granite and hematite were used as coarse aggregates; mining sand and river sand were used as fine aggregates to produce various density and strength of concrete. Concrete samples (150 mm cubes and interlocked blocks) were prepared by changing mix ratio, water to cement ratio (w/c) and types of aggregates. Density, rebound number(N) and ultrasonic pulse velocity (UPV) of the samples were taken before compressed to failure. The measurement results are explained and discussed. (author)

  1. An Automated Image Processing System for Concrete Evaluation

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-11-23

    AlliedSignal Federal Manufacturing & Technologies (FM&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.

  2. An Automated, Image Processing System for Concrete Evaluation

    International Nuclear Information System (INIS)

    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

  3. 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

  4. Performance test on shielding concrete

    International Nuclear Information System (INIS)

    The cylinder of the shielding concrete is made from common Portland cement and home-made coarse or fine aggregates. Orthogonal design experiment and regression analysis are adopted to study the effects of the water content, sand percentage and water-cement ratio on the property of shielding concrete and the difference between them. The test shows that the tensile strength is in inverse proportion with water-cement ratio, and the influence is quite significant. Another factor is the type of aggregates. The effect of the age on its density is not obvious. Similarly, the concrete shielding γ rays shares the same influencing factors with that shielding neutron rays on density, slump and tensile strength. And both have the same change rules regarding to mechanical property. (authors)

  5. Bending characteristics of resin concretes

    Directory of Open Access Journals (Sweden)

    Ribeiro Maria Cristina Santos

    2003-01-01

    Full Text Available In this research work the influence of composition and curing conditions in bending strength of polyester and epoxy concrete is analyzed. Various mixtures of resin and aggregates were considered in view of an optimal combination. The Taguchi methodology was applied in order to reduce the number of tests, and in order to evaluate the influence of various parameters in concrete properties. This methodology is very useful for the planning of experiments. Test results, analyzed by this methodology, shown that the most significant factors affecting bending strength properties of resin concretes are the type of resin, resin content and charge content. An optimal formulation leading to a maximum bending strength was achieved in terms of material parameters.

  6. Design of buried concrete encasements

    International Nuclear Information System (INIS)

    The operation of many Department of Energy (DOE) sites requires the transfer of radioactive liquid products from one location to another. DOE Order 6430.1A requires that the transfer pipelines be designed and constructed so that any leakage can be detected and contained before it reaches the environment. One design option often considered to meet this requirement is to place the pipeline in a stainless steel-lined, buried concrete encasement. This provides the engineer with the design challenge to integrate standard structural design principles with unique DOE requirements. The complete design of a buried concrete encasement must consider seismic effects, leak detection, leak confinement, radiation shielding, thermal effects, pipe supports, and constructability. This paper contains a brief discussion of each of these design considerations, based on experience gained during the design of concrete encasements for the Process Facilities Modifications (PFM) project at Hanford

  7. Maximizing carbon uptake and performance gain in slag-containing concretes through early carbonation

    Science.gov (United States)

    Monkman, Sean

    Carbon dioxide (CO2) emissions have been identified as a major contributor to climate change. Current CO2 mitigation efforts focus on the removal, recovery and disposal of CO2 at point sources. Finding beneficial uses of as-captured or recovered CO2 is a critical challenge in greenhouse gas mitigation. This thesis investigates the possibility of the beneficial use of carbon dioxide in precast concrete production and the performance, both short-term and long-term, of the concretes so produced. The calcium compounds in cementitious materials react readily with carbon dioxide to convert CO2 to thermodynamically stable carbonates. The reaction accelerates strength development and makes the technology appropriate for early age curing. Paste, mortar and concrete samples were examined to quantify such aspects as the carbon dioxide uptake, strength development, and durability of carbonated concrete. It was found that the uptake by the cementitious binders was significant. Compared to their theoretical capacity, cement could reach a carbonation degree of over 25% when treated as pastes and about 20% when used as a part of concrete. The study compared carbonation-cured and hydrated Portland cement concrete and slag cement concretes in terms of their early strength, late strength, weathering carbonation shrinkage, freeze/thaw durability, water absorption, and pH. The carbonated concrete was generally comparable, or superior, to the hydrated concrete except for the case of a 50% GGBF slag blend which had a slower strength development due to reduced secondary cementitious reaction. A second method of binding carbon into concrete was considered by carbonating ladle slag fines and using them as a fine aggregate. The 28-day strength of concrete, either hydrated or carbonation-cured, made with the manufactured slag aggregate was comparable to that of a hydrated concrete made with conventional fine aggregate. Carbon dioxide uptake by concrete was nearly doubled if carbonation

  8. Flexural behavior of reinforced concrete beams: Comparative analysis between high-performance concrete and ordinary concrete

    Directory of Open Access Journals (Sweden)

    Hamrat Mostefa

    2014-04-01

    Full Text Available This paper presents an experimental study on the flexural strength of reinforced concrete beams made with high performance concrete (HPC and ordinary concrete (OC. We are carried an experimental campaign aimed comes in three points: 1- the study of the law of behavior of the two materials (OC and HPC, 2- the influence of the compressive strength of concrete and the rate of longitudinal reinforcement on the loaddeflection behavior and ductility index, 3- comparative analysis (ACI318, Eurocode 2 and BS8110 against the crack opening. Test results showed that the capacity of the beams in HPC is higher (6% to 20 % than the beams in OC. The use of HPC is more efficient than the OC to delay the first cracking. The average value of the ductility index for the beams in HPC is 1.30 times those beams in OC. The formula for calculating the crack opening derived of the Eurocode 2 gives the best prediction the crack width of beams (for both types of concrete.

  9. Reliability Assessment of Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Middleton, C. R.

    This paper is partly based on research performed for the Highways Agency, London, UK under the project DPU/9/44 "Revision of Bridge Assessment Rules Based on Whole Life Performance: concrete bridges". It contains the details of a methodology which can be used to generate Whole Life (WL) reliability...... profiles. These WL reliability profiles may be used to establish revised rules for concrete bridges. This paper is to some extend based on Thoft-Christensen et. al. [1996], Thoft-Christensen [1996] et. al. and Thoft-Christensen [1996]....

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

    Directory of Open Access Journals (Sweden)

    Férriz Papí, J. A.

    2014-03-01

    Full Text Available The exceeding concrete and washing equipment water are a matter to solve in concrete production. This paper explains several possibilities for recycling and analyses the products obtained with one recycling equipment. The objective of this work is to study the possibility to increase the percentage of recycling in new mixes. The developed study relates wash water density and fine particles content. Besides, mortar and concrete samples were tested introducing different quantities of these fine particles, substituting cement, sand or only as an addition. Consistency, compressive strength, setting time, absorption, and capillarity were tested. The results indicated an improvement of the studied properties in some percentages when substituting sand. It confirms the possibility to introduce larger quantities of wash water in new concrete mixes, with corrections in sand quantity depending on water density.Los hormigones frescos sobrantes y aguas procedentes de la limpieza de equipos son un inconveniente a resolver en las plantas de hormigón. Este artículo explica varias posibilidades de reciclado y analiza los productos obtenidos en un equipo reciclador concreto, con el objetivo de estudiar el incremento del porcentaje de reciclaje en nuevas amasadas. El estudio realizado relaciona la densidad del agua de lavado y el contenido de partículas finas. Además, ensaya muestras de mortero y hormigón realizando sustituciones de estas partículas finas por cemento, arena o simplemente como adición. Determina consistencia, resistencia a compresión, principio y fin de fraguado, absorción y capilaridad. Los resultados indicaron un incremento general de las propiedades estudiadas en algunos porcentajes de sustitución por arena. Ello confirma la posibilidad de introducir mayores cantidades de agua de lavado en nuevas amasadas de hormigón, mediante correcciones en la dosificación de arena en función de la densidad del agua.

  11. Influence of Crassostrea gigas on the permeability and microstructure of the surface layer of concrete exposed to the tidal zone of the Yellow Sea.

    Science.gov (United States)

    Lv, JianFu; Mao, JiZe; Ba, HengJing

    2015-01-01

    Concrete exposed to the tidal zone of the Yellow Sea and bearing Crassostrea gigas (CG) with differing areal coverages was investigated for evidence of biologically induced corrosion prevention. The experimental results indicated that both the chloride ion profile and the neutralization depth of the concrete decreased with increasing CG coverage. Moreover, the water absorption rate and the chloride ion permeability of concrete with the original surface intact also declined with increasing degrees of CG coverage. However, the water absorption rates of three concrete samples with 2 mm of the surface layer removed were similar, as was their chloride ion permeability. Mercury intrusion porosimetry tests indicated that CG significantly reduced the pore structure of the concrete surface layer. SEM observation revealed that the CG cementation membrane and left valve were tightly glued to the concrete surface and had a dense structure. Concrete durability indices showed that high CG coverage greatly improved concrete durability. PMID:25584410

  12. Concrete with Highly Active Rice Husk Ash

    Institute of Scientific and Technical Information of China (English)

    FENG Qing-ge; LIN Qing-yu; YU Qi-jun; ZHAO San-ying; YANG Lu-feng; Shuichi Sugita

    2004-01-01

    The overall aim was to investigate the effect of highly active rice husk ash (RHA) produced by an industrial furnace on some properties of concrete. The strength, pore volume and pore distribution of concrete and the Ca(OH)2 content in concrete were investigated by JIS A 1108 (Method of test for compressive strength of concrete), a mercury instrument porosimeter, and the thermogravimetric analysis, respectively. The results show that,with RHA replacement of cement,the compressive strength of concrete is increased evidently;the average pore radius of concrete is greatly decreased, especially the portion of the pores greater than 20nm in radius is decreased while the amount of smaller pores is increased, and the more the RHA replacement, the less the amount of Ca(OH)2 in concrete. The latter two results are the main reasons for the strength enhancement of concrete.

  13. Topology optimization of reinforced concrete structures

    DEFF Research Database (Denmark)

    Amir, Oded

    Recent advances regarding topology optimization procedures of reinforced concrete structures are presented. We discuss several approaches to the challenging problem of optimizing the distribution of concrete and steel reinforcement. In particular, the consideration of complex nonlinear constituti...

  14. Abrasion Properties of Steel Fiber Reinforced Silica Fume Concrete According to Los Angeles and Water Abrasion Tests

    Directory of Open Access Journals (Sweden)

    Tsan-Ching CHENG

    2014-12-01

    Full Text Available The current study mainly investigated the influence of different tests on the abrasion resistance of concrete mixed with steel fibers and silica fume. The abrasion resistance was assessed at 28, 56 and 91 days on concretes with water-binder ratios of 0.35 and 0.55 where in some mixes silica fume was substituted by 5 % of cement by weight. Steel fibers of 0.5 % and 1.0 % of concrete volume were also added into the test concrete by replacement of coarse and fine aggregates. The results showed that concrete with higher compressive strength in Los Angeles abrasion tests also had better abrasion resistance. The inclusion of steel fibers into test concrete with a water-binder ratio of 0.35 resulted in a significant increase in compressive strength. This concrete also displayed better abrasion resistance and splitting tensile strength than reference concrete; in the test sample with a water-binder ratio of 0.55, the added steel fibers was unable to effectively produce cementation with the concrete. The inclusion of silica fume improved the abrasion resistance of concretes. In water abrasion testing, the abrasion resistance of concrete containing steel fiber was worse than that of concrete without steel fibers. In the water abrasion testing, the surface of steel fiber reinforced concrete was eroded by water and steel balls, and the impact caused the steel fibers to separate from the concrete and led to higher wear loss. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6460

  15. High Performance Concrete Pavement in Indiana

    OpenAIRE

    Nantung, Tommy E

    2011-01-01

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

  16. Some Properties of concretes containing recycled aggregates

    OpenAIRE

    DJERBI TEGGUER, Assia; SAILLIO, Mickael; MAIH-NHU, Johnathan; SCHMITT, Lucie; ROUGEAU, Patrick

    2015-01-01

    This paper presents the results of an experimental campaign which aimed at determining the viability of incorporating recycled aggregates from concrete, in the production of a new concrete, with acceptable performances for its use in new structures. Nine concrete mixtures with different recycled aggregates contents and with different water to binder (w/b) ratio were studied. The mean compressive strength for the reference concretes is comprised between 30 and 60 MPa. Tests were performed to m...

  17. Critical Study of Corrosion Damaged Concrete Structures

    OpenAIRE

    Sallehuddin Shah Ayop; John Cairns

    2013-01-01

    Corrosion of steel reinforcement in concrete is one of the major problems with respect to the durability of reinforced concrete structures. The degradation of the structure strength due to reinforcement corrosion decreases its design life. This paper presents the literature study on the influence of the corrosion on concrete structure starting from the mechanism of the corrosion until the deterioration stage and the structural effects of corrosion on concrete structures.

  18. Nanoparticles for high performance concrete (HPC)

    OpenAIRE

    Torgal, Fernando Pacheco; Miraldo, Sérgio; Ding, Yining; Labrincha, J. A.

    2013-01-01

    According to the 2011 ERMCO statistics, only 11% of the production of ready-mixed concrete relates to the high performance concrete (HPC) target. This percentage has remained unchanged since at least 2001 and appears a strange choice on the part of the construction industry, as HPC offers several advantages over normal-strength concrete, specifically those of high strength and durability. It allows for concrete structures requiring less steel reinforcement and offers a longer serviceable life...

  19. Rapid-1 Hardening Accelerator Concrete Admixture

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    SIKA Rapid-1 is a concrete admixture that allows the development of very early high strengths in concrete consisting of commonly used mix components. Unlike concrete set accelerators, it does not reduce set time or long-term strength, and it does not corrode steel reinforcing. This hardening accelerator allows placement of fresh concrete without early stiffening, followed by a period of very rapid strength gain after initial set.

  20. Self Compacting Concrete And Its Properties

    OpenAIRE

    Mahesh, S.

    2014-01-01

    Self-compacting concrete (SCC), which flows under its own weight and doesn’t require any external vibration for compaction, has revolutionized concrete placement. Such concrete should have relatively low yield value to ensure high flow ability, a moderate viscosity to resists segregation and bleeding and must maintain its homogeneity during transportation, placing and curing to ensure adequate structural performance and long term durability. Self-compacting concrete (SCC) ca...

  1. Influence of Silica Fume on Normal Concrete

    OpenAIRE

    Debabrata Pradhan

    2013-01-01

    The incorporation of silica fume into the normal concrete is a routine one in the present days to produce the tailor made high strength and high performance concrete. The design parameters are increasing with the incorporation of silica fume in conventional concrete and the mix proportioning is becoming complex. The main objective of this paper has been made to investigate the different mechanical properties like compressive strength, compacting factor, slump of concrete incorporating silica ...

  2. Research on ZWR Concrete Energy Saving Synergist

    OpenAIRE

    Hu Zhigang

    2015-01-01

    ZWR concrete energy saving synergist used in commodity concrete, were carried out experimental research and engineering application. The results show that the energy-boosters, in ensuring the overall performance of the concrete situation, as its content is 0.6% to 1% in cementitious material can reduce the amount of cement by 10% to 15%, significantly reduces production costs. Without changing the working properties and structural performance of the concrete, this energy saving synergist can ...

  3. Concrete with mineral and chemical addition

    International Nuclear Information System (INIS)

    In the article interpretation of basic result research of cement concrete on astringent with grind wastage flotation concrete florin ore. Prove that introduction the highest wastage in composition astringent in quantitative to 20% from the masses of cement allowed find physical-technical description of concrete. More elective is Mark that, complex introduction in composition of astringent wastage of production florin and chemical plasticizer that will do contribute to acceleration velocity of hydrate wedge mineral of cement and forming strong structure of concrete

  4. Quality control of concrete at the stage of designing its composition and technology

    Energy Technology Data Exchange (ETDEWEB)

    Kudyakov, A., E-mail: kudyakow@mail.tomsknet.ru; Prischepa, I., E-mail: ingaprishepa@mail.ru; Kiselev, D.; Prischepa, B. [Tomsk State University of Architecture and Building, 2 Solyanaya sq., Tomsk, 634003 (Russian Federation)

    2016-01-15

    The results of tests on samples of foam concrete with a hardening accelerator are presented. As the setting and hardening accelerators the following chemical additives were used: Universal-P-2 and Asilin 12. All additives were added into the insulating foam concrete mix of brand D 400 in the amount of 0.5% to 1% of cement weight. By using of additives in foam concrete technology – hardening accelerators Asilin 12 and Universal P2 in the amount of 0.5 % - and 1.0% by weight of cement foam concrete structure formation is accelerated and increases strength by 60%. For the industrial preparation of foam concrete mix technological regulations are worked out, in which it is recommended to use additives – hardening accelerators Asilin 12 in the amount of 0.5% and Universal P2 - 1% of cement weight.

  5. Quantitative formulation of mechanism of sintering process during creep deformation of refractory concretes

    Directory of Open Access Journals (Sweden)

    Terzić Anja

    2009-01-01

    Full Text Available This paper is concerned with quantitative formulation of the mechanism of the sintering process during secondary state creep deformation of refractory concretes. Investigated concretes varied in, both, chemical and mineralogical compositions. The sintering process during secondary state creep within refractory concrete has an isothermal character. Thus, an attempt was made to describe the mentioned process quantitatively. Creep was investigated at three different temperatures: 1200, 1300 and 1400ºC. Variations of the microstructure of concrete samples, exposed to constant static pressure and constant temperature during certain time-intervals, were investigated using a scanning electron microscope. Obtained results of the investigation proved that creep resistance is an irreplaceable method when the decision about the best possible type of refractory concrete for application in metallurgical furnaces is required.

  6. Quality control of concrete at the stage of designing its composition and technology

    International Nuclear Information System (INIS)

    The results of tests on samples of foam concrete with a hardening accelerator are presented. As the setting and hardening accelerators the following chemical additives were used: Universal-P-2 and Asilin 12. All additives were added into the insulating foam concrete mix of brand D 400 in the amount of 0.5% to 1% of cement weight. By using of additives in foam concrete technology – hardening accelerators Asilin 12 and Universal P2 in the amount of 0.5 % - and 1.0% by weight of cement foam concrete structure formation is accelerated and increases strength by 60%. For the industrial preparation of foam concrete mix technological regulations are worked out, in which it is recommended to use additives – hardening accelerators Asilin 12 in the amount of 0.5% and Universal P2 - 1% of cement weight

  7. Quality control of concrete at the stage of designing its composition and technology

    Science.gov (United States)

    Kudyakov, A.; Prischepa, I.; Kiselev, D.; Prischepa, B.

    2016-01-01

    The results of tests on samples of foam concrete with a hardening accelerator are presented. As the setting and hardening accelerators the following chemical additives were used: Universal-P-2 and Asilin 12. All additives were added into the insulating foam concrete mix of brand D 400 in the amount of 0.5% to 1% of cement weight. By using of additives in foam concrete technology - hardening accelerators Asilin 12 and Universal P2 in the amount of 0.5 % - and 1.0% by weight of cement foam concrete structure formation is accelerated and increases strength by 60%. For the industrial preparation of foam concrete mix technological regulations are worked out, in which it is recommended to use additives - hardening accelerators Asilin 12 in the amount of 0.5% and Universal P2 - 1% of cement weight.

  8. Radiological assessment of the utilization of fly ash in concrete for building construction and the parameters affecting radon-222 emanation from fly ash concrete

    International Nuclear Information System (INIS)

    In this study, the Rn-222 area exhalation rates and the maximum area exhalations for concrete containing fly ash or Ra-226 water were measured. Various concrete samples were fabricated with fly ash of known radium content as a cement substitute. Other samples were prepared with one of three concentrations of Ra-226 water solution added into the concrete mix. A newly designed Indoor/Outdoor Emanation Chamber. The Ra-225 concentrations for the fly ash used ranged from 3.42 pCi/g to 7.55 pCi/g depending upon the source of the ash and the particle size. Doses were calculated for occupants of a hypothetical house built with concrete of the type studied. Doses to the basal cells of the bronchial epithelium and the mean dose to the lung were 2.10 rad/yr and 0.37 rad/yr for standard concrete, up to 4.28 rad/yr and 0.76 rad/yr for fly ash concrete, and 3.26 rad/yr and 0.58 rad/yr for the concrete made with 25 pCI/L radium-226 water. The risk associated with utilization of standard concrete in an unventilated house was estimated to range from 560 to 1316 fatal cancers in million population. Utilization of fly ash as a cement substitute could increase the number of fatal lung cancers up to 2680. Introducing 25 pCi/L Ra-226 water into concrete will increase the fatal cancer rate up to 2042 in a million population

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

    OpenAIRE

    Osei, Daniel Yaw

    2013-01-01

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

  10. Investigation of the Usability of Travertine Quarry Wastes As Concrete Aggregate

    Directory of Open Access Journals (Sweden)

    İbrahim Çobanoğlu

    2014-03-01

    Full Text Available Denizli basin is one of the most important travertine deposition area around the world. Kaklık, Kocabaş, Honaz, Aşağıdağdere, Akköy, Çivril are major production areas. Tectonic activity in the region has been negatively affected the block production efficiency in the quarries. Quarry wastes by wire cutting are collected in waste disposal areas and these materials do not use for any other purposes. In this study, investigation of usability of different sized travertine quarry wastes in concrete as aggregate is aimed. For this purpose, physico mechanical properties of aggregates were investigated and concrete mixtures were prepared. Strength of 7, 28 and 56 days concrete samples which are targeted of C30 concrete class were also determined. Strength of prepared travertine aggregated concrete compared to still being produced concrete. For comparison, all procedures were performed for limestone aggregated concrete. Thin sections were prepared for investigations of distribution and coupling of grains in cement material under polarizan microscope. 32.80-42.70 MPa and 39.34-46.04 MPa strengths were determined for travertine aggregated and limestone aggregated concretes respectively. By using travertine aggregate, limit values for C30 concrete class have been reached. This study demonstrates that the travertine quarry wastes can be used as aggregates in concrete. In Denizli region there is no concrete firm use travertine wastes as aggregate. It is thought that, as an alternative building material travertine can be used in production of brick, curbs, keystone and various materials. For this aim more detailed experimental studies on travertines are needed.

  11. 9 CFR 91.26 - Concrete flooring.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Concrete flooring. 91.26 Section 91.26... LIVESTOCK FOR EXPORTATION Inspection of Vessels and Accommodations § 91.26 Concrete flooring. (a) Pens aboard an ocean vessel shall have a 3 inch concrete pavement, proportioned and mixed to give 2000...

  12. Prediction of Deterioration of Concrete Bridges

    NARCIS (Netherlands)

    Gaal, G.C.M.

    2004-01-01

    In the early 20th century, the general idea was that concrete structures would never show deterioration. However, in the 1990s concrete structures showed an increase in number of cracks and area of spalling. Especially spalling of the concrete cover could create a harmful situation to the users. Spa

  13. Improved set-up for determination of bitumen content in asphalt concrete by the neutron reflection method

    International Nuclear Information System (INIS)

    A set-up was developed for the determination of bitumen in asphalt concrete by the neutron reflection method. The main parts of this set-up include an Am-Be neutron source (1 Ci) and a 3He neutron detector. To avoid geometrical effects on the measurements, the optimum sample volume was determined from the neutron response vs volume sample plot. The AST method (ASTM) was used for calibration when preparing the aggregate and asphalt concrete samples. The method was compared to the conventional chemical method by analysing unknown samples taken from the asphalt concrete producing plant. The method was characterized by its reproducibility, sensitivity and precision

  14. Computational modeling of concrete flow

    DEFF Research Database (Denmark)

    Roussel, Nicolas; Geiker, Mette Rica; Dufour, Frederic; Thrane, Lars Nyholm; Szabo, Peter

    2007-01-01

    This paper provides a general overview of the present status regarding computational modeling of the flow of fresh concrete. The computational modeling techniques that can be found in the literature may be divided into three main families: single fluid simulations, numerical modeling of discrete...

  15. Study of Recycled Concrete Aggregates

    OpenAIRE

    Jitender Sharma; Sandeep Singla

    2014-01-01

    This paper describes the introduction and production of recycled concrete aggregates and its various applications in the construction industry. In this paper, properties of recycled aggregates and its comparison with the natural aggregates are also mentioned. Future recommendations about RCA are also included.

  16. Early Reading and Concrete Operations.

    Science.gov (United States)

    Polk, Cindy L. Howes; Goldstein, David

    1980-01-01

    Indicated that early readers are more likely to be advanced in cognitive development than are nonearly-reading peers. After one year of formal reading instruction, early readers maintained their advantage in reading achievement. Measures of concrete operations were found to predict reading achievement for early and nonearly readers. (Author/DB)

  17. Novel techniques for concrete curing

    DEFF Research Database (Denmark)

    Kovler, Konstantin; Jensen, Ole Mejlhede

    2005-01-01

    lightweight aggregate, superabsorbent polymers or water-soluble chemicals, which reduce water evaporation (so called "internal sealing"). These concepts have been intensively researched in the 90s, but still are not widespread among contractors and concrete suppliers. The differences between conventional...

  18. Large Scale Glazed Concrete Panels

    DEFF Research Database (Denmark)

    Bache, Anja Margrethe

    2010-01-01

    Factories and finally Lene Tranberg and Bøje Lungård’s Elsinore water purification plant. These buildings have qualities that I would like applied, perhaps transformed or most preferably, if possible, interpreted anew, for the large glazed concrete panels I shall develop. The article is ended and concluded...

  19. Timber-concrete composite beams

    NARCIS (Netherlands)

    Van der Linden, M.L.R.

    1999-01-01

    In this paper an easy-to-use design model for timber-concrete composite beams is discussed. The model is applicable for computer simulations as well as for hand calculations. A research programme was started in 1992 in co-operation with the University of Karlsruhe, to study the loadbearing capacitie

  20. Timber floors strengthened with concrete

    NARCIS (Netherlands)

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

    1998-01-01

    Timber-concrete composite (tcc) beams may be used for the renovation of old timber floors. Although these systems are not new (Pokulka, 1997) and form a simple and practical solution, they are not widely adopted. One of the reasons for this is the Jack of uniform design rules. In this research progr

  1. Early Property Development in Concrete

    DEFF Research Database (Denmark)

    Normann, Gitte; Munch-Petersen, Christian

    2014-01-01

    The Freiesleben Maturity function is widely used for planning of execution. We tested if for concrete with and without fly ash. The test showed surprisingly that the maturity function in general is not valid. We found that curing at high temperature gave a significant decrease in strength. Fly ash...

  2. A Failure Criterion for Concrete

    DEFF Research Database (Denmark)

    Ottosen, N. S.

    1977-01-01

    A four-parameter failure criterion containing all the three stress invariants explicitly is proposed for short-time loading of concrete. It corresponds to a smooth convex failure surface with curved meridians, which open in the negative direction of the hydrostatic axis, and the trace in the devi...

  3. Development of Geopolymer Concrete with Different Curing Conditions

    Directory of Open Access Journals (Sweden)

    M.F. Nuruddin Nuruddin

    2011-02-01

    Full Text Available Environmental issues resulted from cement production have become a major concern today. To develop a sustainable future it is encouraged to limit the use of this construction material that can affect the environment. Cement replacement material was proposed to partially replace cement portion in concrete. Geopolymer is a part of inorganic polymer material that has similar bonding function like cement in concrete. It consists of alkaline solutions and geological source material. Alkaline liquids used in this research are 8 M sodium hydroxide (NaOH solution and sodium silicate (Na2SiO3 solutions, while source materials are fly ash and microwave incinerated rice husk ash (MIRHA. Three different curing regimes, namely hot gunny curing, ambient curing, and external exposure curing, were applied to obtain suitable method that was suitable with cast in situ application. Geopolymer concrete samples were tested on their compressive strength and microstructure properties. It was found that external exposure curing had the highest compressive strength compared to other two curing methods. Scanning electron microscopy analysis also showed better improvement in interfacial transition zone for concrete sample with external exposure curing.

  4. Nondestructive testing technology to characterize concrete dam/bedrock interface

    International Nuclear Information System (INIS)

    It is essential that there be knowledge of the in situ conditions and properties of the interface between the concrete and bedrock foundation when assessing the stability of hydraulic structures. Such information typically comes from core sampling and laboratory testing of specimens containing the concrete/bedrock interface. The approach only yields information on a small percentage of the contact area, and the test results may be affected by disturbance of the samples during coring with the result that interpretation is required to derive an average value for the condition of the contact. Nondestructive testing using ultrasonic velocity measurements including the use of tomographic imaging were evaluated as a means of obtaining additional information on a concrete dam foundation. An assessment was carried out based on the results of a field trial at a large gravity dam to determine the ability of these methods to provide greater confidence in estimating the condition of the concrete/bedrock interface. Field trials confirmed that ultrasonic testing methods are capable of identifying the general foundation profile, and the technology can also provide information regarding the general integrity of the contact zone. Such information taken in conjunction with the results of a coring and laboratory testing program can greatly improve confidence in the evaluation of the foundation contact condition and the selection of strength parameters used for assessment. 5 refs., 6 figs

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

    OpenAIRE

    Hongying Dong; Wanlin Cao; Jianhui Bian; Jianwei Zhang

    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...

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

    OpenAIRE

    Zhupeng Zheng; Ying Lei

    2014-01-01

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

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

    OpenAIRE

    Fangping Liu; Jianting Zhou

    2016-01-01

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

  8. The Influence of Crushed Concrete Demolition Waste Aggregates on the Hardening Process of Concrete Mixtures

    OpenAIRE

    Olga FINOŽENOK; Ramunė ŽURAUSKIENĖ; Rimvydas ŽURAUSKAS

    2013-01-01

    Concrete – complex structure composite material consisting of the components with various structure and size. Not only coarse and fine aggregates are used in concrete production, but also filler aggregates. Aggregates of natural, man-made origin or aggregates, produced from recycled materials, can be utilised in concrete production. Aggregates can be produced from recycled materials by reprocessing of concrete and reinforced concrete waste. The influence of the filler aggregates produced from...

  9. Determination Strength of Concrete in-Situ by Seismic Ultrasonic Method in Detecting Risky Structure

    Science.gov (United States)

    Uyanik, O.; Öziçer, S.; Sabbağ, N.

    2014-12-01

    Strength of concrete is important in the analysis of structures. Strength of concrete can be determined as destructive or non destructive. In order to determine to strength of concrete as destructive, core is taken from concrete parts of the structure and uniaxial compressive strength test is applied in the laboratory. In contrast, strength of concrete can be determined as non destructive in situ by seismic ultrasonic technique. In this study, seismic ultrasonic P wave velocity measurements. Schmidt hammer test in situ and core sampling along with uniaxial compressive test are carried out in order to determine the strength of concrete in existing structures in Bornova district of İzmir. Seismic ultrasonic P wave velocity measurements in situ were also applied on the core. The concrete strength values obtained from techniques applied in study were compared and error values are determined. By seismic ultrasonic P wave velocity measurements with error value %5 strength of concrete is determined quickly without any destruction on structures studied.

  10. Effect of applied load on the nondestructive measurement of concrete strength

    Science.gov (United States)

    Mahmoudabadi, E.; Amjad, U.; Kundu, T.; Saadatmanesh, H.

    2014-03-01

    Nondestructive measurement of the concrete strength is an important topic of research. Among different nondestructive testing (NDT) methods the ultrasonic pulse velocity (UPV) technique is the most popular method for concrete strength estimation. While measuring concrete strength by this method almost all researchers have neglected the effect of applied stress or load on the concrete member. In this investigation attempts were made to properly incorporate the effect of the applied load on the strength prediction of concrete specimens from UPV value. To achieve this goal, 4 groups of concrete specimens with different values of final strength were made. Materials used for making cylindrical specimens of 3 inch diameter and 6 inch height included regular Portland cement, water and two types of aggregate - fine and coarse. After applying the load on the specimen in multiple steps - up to 70% of its failure strength fc'- the time of flight (TOF) value was measured for every loading step. The recorded results showed that applied load on the member has significant effect on the measured UPV value on concrete specimens. Therefore, to find the strength of the concrete from the UPV value, the applied load on the sample should be considered as an important factor that cannot be neglected.

  11. An experimental study on the estimation of the strength of hardened concrete

    International Nuclear Information System (INIS)

    The need to asses the strength of hardened concrete in an existing structure can arise from a variety of reasons, especially such as doubt of non-destructive test methods. According the study aims at suggesting the practical basic material through sampling the concrete conveyed to the construction site by mixer truck shortly before its placing, employing the non-destructive test methods and the location surveying compressive strength test methods with regard to the compressive strength of the concrete after 28 days of age passed after the placing of concrete, securing the uniformity of concrete structure, and comparing and analyzing the difference between the non-destructive test methods and the location surveying compressive strength. The test was conducted in the following methods at the concrete placing work on the real site, as the test able among several factors which execute on effect on compressive strength in this study. Used concrete was the Remicon product of A company, and cured until 28 days of aging by water curing, drawing up the standard cylinder specimen on The construction site. The estimated formula of the compressive strength, in accordance with the results of the experiments conducted by the Schmidt Hammer test method and the ultrasonics pulse velocity test method, Air Exclusion Test method are as follows : (1) Schmidt Hammer Test Method Fc = 16.75R - 325.5 (2) Ultra Sonic Test Method Fc = 277.22VP - 846.78 (3) Concrete Air Exclusion Rating Table.

  12. Dynamic testing of concrete under high confined pressure. Influence of saturation ratio and aggregate size

    Directory of Open Access Journals (Sweden)

    Forquin P.

    2015-01-01

    Full Text Available Concrete structures can be exposed to intense pressure loadings such as projectile-impact or detonation near a concrete structural element. To investigate the mechanical behaviour of concrete under high confining pressure, dynamic quasi-oedometric compression tests have been performed with a large diameter (80 mm Split Hopkinson Pressure Bar apparatus. The concrete sample is placed within a steel confining ring and compressed along its axial direction. Hydrostatic pressures as high as 800 MPa and axial strain of about − 10% are reached during the tests. In the present work, experiments have been conducted on two types of concrete: MB50 microconcrete with a maximum grain size of 2 mm and R30A7 ordinary concrete of maximum grain size about 8 mm. Both concretes are tested in dry or saturated conditions. According to these dynamic experiments it is noted that grain size has a small influence whereas water content has a strong effect on the confined behaviour of concrete.

  13. A thermo-plastic model of the high temperature behaviour of concrete

    International Nuclear Information System (INIS)

    The aim of this work is to develop a model about the behaviour of concrete in the 20-800 deg. C temperature range which covers most of the fire hazard and nuclear accident situations. In this temperature range, the concrete microstructure is submitted to physico-chemical changes which greatly influence its behaviour. The main phenomena in concern were identified first and an on-line thermo-mechanical bench scale analysis was performed on concrete test specimens. A model related to the thermo-plasticity theory is proposed to describe the non-linear behaviour of concrete when submitted to traction and compression. A plasticity and rupture criterion was built to describe the specific high-temperature behaviour of this material. The irreversible variations with temperature of the thermal and mechanical characteristics of concrete were taken into account. The deformations due to thermo-mechanical interactions occurring during the first heating of a loaded concrete sample were taken into account in the form of transient creep deformations. An implicit scheme adapted to temperature-dependent characteristics was used to integrate the constituent equations. Different types of concrete and reinforced concrete structures were analyzed during high-temperature isothermal or transient situations. The numerical results obtained were compared to experimental results. (J.S.)

  14. Effect of Gum Arabic karroo as a Water-Reducing Admixture in Concrete

    Directory of Open Access Journals (Sweden)

    Rose Mbugua

    2016-01-01

    Full Text Available Concrete is one of the most popular construction materials in the world. Chemical admixtures are ingredients added to concrete to enhance its properties. However, most chemical admixtures on the market today are expensive, thereby making them out of reach for small consumers of concrete. In Africa, use of chemical admixtures is rare despite the harsh weather conditions. In the current study, Gum from Acacia karroo (GAK was used as a water-reducing admixture in concrete. A slump test, density and compressive strength were studied using different dosages of GAK while neat concrete was the control. Results showed that slump increased by 200% at a 2% dosage of GAK. This enabled reduction of water-to-binder (w/b ratio from 0.61 to 0.48 for samples with a 3% dosage. Reduction in w/b resulted in increased compressive strength of 37.03% above the control after 180 days of curing for a 3% dosage. XRD studies also showed a decreased rate of hydration in the presence of GAK in concrete. It was concluded that GAK can be used in concrete as a water-reducing admixture, which is environmentally-friendly, thus producing sustainable and greener concrete.

  15. Identification of concrete deteriorating minerals by polarizing and scanning electron microscopy

    International Nuclear Information System (INIS)

    The deterioration of concrete represents one of the most serious problems of civil engineering worldwide. Besides other processes, deterioration of concrete consists of sulfate attack and carbonation. Sulfate attack results in the formation of gypsum, ettringite and thaumasite in hardened concrete. Products of sulfate attack may cause a loss of material strength and a risk of collapse of the concrete constructions. The authors focused especially on the microscopical research of sulfate attack. Concrete samples were taken from the Charles Bridge in Prague, Czech Republic. A succession of degrading mineral formation was suggested. Microscope methods represent a new approach to solving the deterioration problems. They enable evaluation of the state of concrete constructions and in cooperation with hydro-geochemistry, mathematics and statistics permit prediction of the durability of a structure. Considering the number of concrete constructions and their age, research of concrete deterioration has an increasing importance. The results obtained can also be useful for future construction, because they identify the risk factors associated with formation of minerals known to degrade structures.

  16. Evaluation of density, moisture content and percentage compaction of concrete using direct transmission and backscatter methods

    International Nuclear Information System (INIS)

    The nuclear method widely used in determining the density and moisture content of soil - aggregates, asphalt concretes, roller compacted concretes and Portland cement concretes, is the radiometry technique. Generally, all radiometry systems consist of a source of radiation, the sample being examined and a radiation detector. In operation, a radioactive source and a detector are placed on the same or opposite sides of a concrete sample. A portion of radiation from the source which passes through the concrete sample and reaches the detector produces a series of electrical pulses which when counted gives a measure of the dimensions or physical characteristics of the concrete sample. In this research work, concrete beams were fabricated using a 500 x 225 x 200mm wooden mould whiles a table vibrator was used to consolidate the concrete after placement in the mould. The mass of the beam was determined and the actual density calculated and inputted in the gauge. Measurements were performed on the unhardened and hardened concrete using the backscatter method and the direct transmission method at depths of 50mm, 100mm and 150mm. The measuring times of 15, 60 and 240 second were use to take the measurements. The study provided information on the variation of density with depth and this was observed to be within the range of 0 kg/m3 to 1 kg/m3 and 13 kg/m3 to 23 kg/m3 for the unhardened concrete samples in which density increased with depth and those in which density decreased with depth respectively. For the hardened concrete sample, the average change in density with depth was between 4 - 11 kg/m3 for the samples in which density increased with depth and between 11 - 21 kg/m3 for the samples in which density decreased with depth. The study also provided information about the degree of consolidation of Portland cement concrete which on the average was between 95% - 97% for the unhardened concrete samples and increased to between 97% - 99% for the hardened concrete samples

  17. Mock-up experiments for the project of high dose irradiation on the RPV concrete

    International Nuclear Information System (INIS)

    Aging of NPP's concrete structures comes into growing interest in connection with solution of life extension programmes of operated units. Securing continued safe operation of NPPs calls for additional proofs of suitable long term behaviour of loaded reinforced concrete structures. An irradiation test of concrete samples was performed in the core of the LVR-15 reactor. The irradiation capsule was hung in the irradiation channel and the cooling of the capsule was ensured through direct contact of the capsule wall with the primary circuit water. Cylindrical, serpentine concrete samples (50 mm in diameter and 100 mm in length), representing composition of WWER RPV cavity, was chosen as a compromise of mechanical properties testing needs and dimension limitations of reactor irradiation channel. Heating during irradiation test was maintained under 93 Celsius degrees by cooling and was controlled by embedded thermocouple. Design of the cooling management was supported by computational analysis. The dependencies of heated concrete samples to the neutron fluence and the gamma heating were obtained by changing the thermal power of the reactor and by changing the vertical position of the sample in the irradiation channel. The irradiation capsule was filled with inert gas (helium) to allow the measurement of generated gas. The determination of concrete samples activity for long-term irradiation was performed on the principles of the Neutron Activation Analysis. Preliminary mock-up tests have proved the ability to fulfill technical needs for planned high dose irradiation experiment

  18. Ageing degradation in the Gentilly-1 concrete containment building

    International Nuclear Information System (INIS)

    Concrete containment buildings (CCBs) are designed for a service life up to 40 years, but nuclear power plant (NPP) refurbishment can extend service life beyond 60 years. Only limited testing can be conducted on an in-service CCB. The Gentilly-1 (G-1) NPP is in a safe, sustainable shutdown state and the G-1 CCB was available for testing to determine age-related degradation that may be relevant to operating CCBs. Visual observation of the G-1 CCB helped to identify various signs of degradation. However, field testing, via concrete removal, was performed to: (i) examine reinforcing bars and concrete to determine their condition and in-situ stresses and (ii) examine condition of post-tensioned (P-T) wires. The concrete was also subjected to laboratory tests to evaluate its physical, mechanical and chemical properties such as compressive strength, carbonation depth, chloride content and presence of internal degradation. The degradation mechanisms that were clearly visible include macro- and micro-cracking, efflorescence, and weathering. The reinforcing bars in the perimeter wall and dome exposed during the program showed no evidence of active corrosion. Corrosion products were observed on the surfaces of most exposed P-T wires in the perimeter wall, but none were present on P-T wires exposed in the dome. Laboratory testing on the concrete cores extracted from the CCB revealed compressive strength in excess of the design requirements, low carbonation depths (< 10 mm) and no appreciable chlorides. Micro-cracking was observed in the samples recovered from the wall and dome. To date, the observed micro-cracking has had no apparent visible affect on the performance of the CCB concrete. (authors)

  19. Elastic-plastic constitutive modeling of concrete

    International Nuclear Information System (INIS)

    The need to understand concrete behavior under high temperatures in the nuclear industry has become rather accute. For this purpose, a constitutive model of concrete especially developed for this severe environment is indispensable. This report reviews the presently available constitutive models of concrete at standard-temperature conditions and considers their advantages and drawbacks. A rather simple but effective approach is selected to treat concrete behavior at high temperatures. Special emphasis is devoted to the modeling of concrete up to and including failure. The derived constitutive model is checked with biaxial and triaxial benchmark experimental results. Very good agreement is obtained

  20. Mechanical characterization of fiber reinforced Polymer Concrete

    Directory of Open Access Journals (Sweden)

    João Marciano Laredo dos Reis

    2005-09-01

    Full Text Available A comparative study between epoxy Polymer Concrete plain, reinforced with carbon and glass fibers and commercial concrete mixes was made. The fibers are 6 mm long and the fiber content was 2% and 1%, respectively, in mass. Compressive tests were performed at room temperature and load vs. displacement curves were plotted up to failure. The carbon and glass fibers reinforcement were randomly dispersed into the matrix of polymer concrete. An increase in compressive properties was observed as function of reinforcement. The comparison also showed that Polymer Concrete, plain and reinforced, has a better performance than regular market concrete, suggesting that PC is a reliable alternative for construction industry.

  1. Concrete structures protection, repair and rehabilitation

    CERN Document Server

    Woodson, R Dodge

    2009-01-01

    The success of a repair or rehabilitation project depends on the specific plans designed for it. Concrete Structures: Protection, Repair and Rehabilitation provides guidance on evaluating the condition of the concrete in a structure, relating the condition of the concrete to the underlying cause or causes of that condition, selecting an appropriate repair material and method for any deficiency found, and using the selected materials and methods to repair or rehabilitate the structure. Guidance is also provided for engineers focused on maintaining concrete and preparing concrete investigation r

  2. Strength of Concrete Containing Basalt Fibre

    Directory of Open Access Journals (Sweden)

    Parvez Imraan Ansari

    2015-04-01

    Full Text Available This paper presents the comparative study of effect of basalt fibre on compressive and split tensile strength of M40 grade concrete. The basalt fibre was mixed in concrete by (0.5%, 1%, and 1.5% of its total weight of cement in concrete. Results indicated that the strength increases with increase of basalt fibre content up to 1.0% beyond that there is a reduction in strength on increasing basalt fibre. The results show that the concrete specimen with 1.0% of basalt fibre gives better performance when it compared with 0.5%and 1.5% basalt fibre mix in concrete specimens.

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

    International Nuclear Information System (INIS)

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

  4. Durable fiber reinforced self-compacting concrete

    International Nuclear Information System (INIS)

    In order to produce thin precast elements, a self-compacting concrete was prepared. When manufacturing these elements, homogenously dispersed steel fibers instead of ordinary steel-reinforcing mesh were added to the concrete mixture at a dosage of 10% by mass of cement. An adequate concrete strength class was achieved with a water to cement ratio of 0.40. Compression and flexure tests were carried out to assess the safety of these thin concrete elements. Moreover, serviceability aspects were taken into consideration. Firstly, drying shrinkage tests were carried out in order to evaluate the contribution of steel fibers in counteracting the high concrete strains due to a low aggregate-cement ratio. Secondly, the resistance to freezing and thawing cycles was investigated on concrete specimens in some cases superficially treated with a hydrophobic agent. Lastly, both carbonation and chloride penetration tests were carried out to assess durability behavior of this concrete mixture

  5. Organisms adaptable concrete. Eco-concrete for fresh water area; Seibutsu to kyoseisuru eco-concrete. Tansuiiki taiogata eco-concrete

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, k. [Hokkaido Development Bureau, Hokkaido Development Agency, Sapporo (Japan); Shindo, K. [Kyowa Concrete Industry Co. Ltd., Sapporo (Japan)

    1998-03-01

    Described herein are the current statuses of organisms in fresh water and organisms adaptable concrete for fresh water use, and results of the tests in which cylindrical blocks of porous concrete are placed in fresh water to follow types of organisms clinging to them and temporal changes in their numbers. These tests have confirmed that porous concrete can be used as the one compatible with the environment, because large quantities of aqueous insects and algae are found to cling to these blocks. The major findings are: larger quantities of aqueous insects cling to porous concrete than to ordinary one, and sometimes than to natural river floors; no effect of concrete composition on algae clinging thereto is observed; types of algae clinging to porous concrete are diversified with time; and it is possible to minimize changes in natural environments by replacing ordinary concrete by porous one. 6 refs., 10 figs.

  6. Investigations of deteriorated concrete from the liner of the Waste Isolation Pilot Plant Waste Shaft

    International Nuclear Information System (INIS)

    During inspections of the Waste Isolation Pilot Plant Waste Shaft in May 1990, patchy areas of apparently degraded concrete were observed on the inner surface of the shaft liner between approximately 810 feet and 900 feet below the surface. The apparent cause of this degradation is chemical reaction of the concrete with magnesium-bearing brine in the annulus between the concrete liner and the host rock. The greater thickness of the degraded layer below the joint may be related to the different chemical compositions that were determined by analyses of the paste portions of concrete samples from above and below the joint. The analytical results support a complex mechanistic explanation of concrete degradation observed behind the liner and in the joint: chemical weakening of the concrete paste; cracking by precipitation of solids in pores; and increased permeability due to calcium chloroaluminate formation. Additional sampling, analyses, and regular monitoring are worth considering to bound the vertical extent of Waste Shaft liner degradation, detect concrete liner degradation in other shafts, and measure any ongoing degradation that may be occurring

  7. In situ processing of concrete surface by impregnation and polymerization of an organic resin

    International Nuclear Information System (INIS)

    The impregnation by resins of concrete structures is widely known as PIC (Polymer Impregnated Concrete). This process is normally used to improve the physical-chemical features of prefabricated items in particular to raise their lifetime under severe environmental conditions. The main target of this research contract was the verification of the possibility of a proper impregnation of existing concrete surfaces, of any dimensions and position, by comparing the obtained characteristics with those of untreated original material to check the improvement of chemical-physical properties and durability. In a nuclear facility, this goal is very important with reference to the long-term integrity of concrete walls during plant operative lifetime and after the final shutdown and decommissioning of the plant, if its dismantling is deferred. The operative steps of the research were the design, manufacturing and implementation of a tailored prototype equipment, the setting-up of the machine, the project and erection of a walling unit made of different density sectors in nuclear grade concrete and optimisation of the PIC process phases (dehydration, degassing, monomer injection, thermal cycles) during the experimental campaign. The data collected from samples gathered from field application gave results very similar to laboratory impregnated samples, thus confirming the satisfactory running of the prototype unit. Particularly the resin penetration, in spite of low porosity of nuclear grade concrete matrix, reached depths well beyond 50 mm with a significant increase of mechanical features, leaching resistance to aggressive agents and an appreciable sealing of concrete porosity

  8. Designing Concrete Of New Era:“Self Compacting Concrete

    OpenAIRE

    Dharmesh K. Bhagat; Nandan H. Dawda

    2014-01-01

    In India, infrastructure is given prior importance and it is vision to make India fully developed up till 2020.But, it is a challenging job to produce high strength concrete and one of the problems for this is presence of air voids. At present to reduce these voids many compacting machines like vibrators are used in field. But, this leads to high noise pollution and annoyance the person working on site. Thus, to eliminate this problem related to compaction, strength and noise,...

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

    DEFF Research Database (Denmark)

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

    1997-01-01

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

  10. Preliminary investigation on the suitablity of using fiber reinforced concrete in the construction of a hazardous waste disposal vessel

    Energy Technology Data Exchange (ETDEWEB)

    Ramey, M.R.; Daie-e, G.

    1988-07-01

    There are certain hazardous wastes that must be contained in an extremely secure vessel for transportation and disposal. The vessel, among other things, must be able to withstand relatively large impacts without rupturing. Such containment vessels therefore must be able to absorb substantial amounts of energy during an impact and still perform their function. One of the impacts that the vessel must withstand is a 30-foot fall onto an unyielding surface. For some disposal scenarios it is proposed to encase the waste in a steel enclosure which is to be surrounded by a thick layer of concrete which, in turn, is encased by a relatively thin steel shell. Tests on concrete in compression and flexure, including static, dynamic and impact tests, have shown that low modulus concretes tend to behave in a less brittle manner than higher modulus concretes. Tests also show that fiber reinforced concretes have significantly greater ductility, crack propagation resistance and toughness than conventional concretes. Since it is known that concrete is a reasonably brittle material, it is necessary to do impact tests on sample containment structures consisting of thin-walled metal containers having closed ends which are filled with concrete, grout, or fiber reinforced concrete. This report presents the results of simple tests aimed at observing the behavior of sample containment structures subjected to impacts due to a fall from 30 feet. 8 figs., 4 tabs.

  11. Preliminary investigation on the suitablity of using fiber reinforced concrete in the construction of a hazardous waste disposal vessel

    International Nuclear Information System (INIS)

    There are certain hazardous wastes that must be contained in an extremely secure vessel for transportation and disposal. The vessel, among other things, must be able to withstand relatively large impacts without rupturing. Such containment vessels therefore must be able to absorb substantial amounts of energy during an impact and still perform their function. One of the impacts that the vessel must withstand is a 30-foot fall onto an unyielding surface. For some disposal scenarios it is proposed to encase the waste in a steel enclosure which is to be surrounded by a thick layer of concrete which, in turn, is encased by a relatively thin steel shell. Tests on concrete in compression and flexure, including static, dynamic and impact tests, have shown that low modulus concretes tend to behave in a less brittle manner than higher modulus concretes. Tests also show that fiber reinforced concretes have significantly greater ductility, crack propagation resistance and toughness than conventional concretes. Since it is known that concrete is a reasonably brittle material, it is necessary to do impact tests on sample containment structures consisting of thin-walled metal containers having closed ends which are filled with concrete, grout, or fiber reinforced concrete. This report presents the results of simple tests aimed at observing the behavior of sample containment structures subjected to impacts due to a fall from 30 feet. 8 figs., 4 tabs

  12. Characterization of basin concrete in support of structural integrity demonstration for extended storage

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, A. [Savannah River National Laboratory, Aiken, SC (United States)

    2014-09-30

    Concrete core samples from C basin were characterized through material testing and analysis to verify the design inputs for structural analysis of the L Basin and to evaluate the type and extent of changes in the material condition of the concrete under extended service for fuel storage. To avoid the impact on operations, core samples were not collected from L area, but rather, several concrete core samples were taken from the C Basin prior to its closure. C basin was selected due to its similar environmental exposure and service history compared to L Basin. The microstructure and chemical composition of the concrete exposed to the water was profiled from the water surface into the wall to evaluate the impact and extent of exposure. No significant leaching of concrete components was observed. Ingress of carbonation or deleterious species was determined to be insignificant. No evidence of alkali-silica reactions (ASR) was observed. Ettringite was observed to form throughout the structure (in air voids or pores); however, the sulfur content was measured to be consistent with the initial concrete that was used to construct the facility. Similar ettringite trends were observed in the interior segments of the core samples. The compressive strength of the concrete at the mid-wall of the basin was measured, and similar microstructural analysis was conducted on these materials post compression testing. The microstructure was determined to be similar to near-surface segments of the core samples. The average strength was 4148 psi, which is well-above the design strength of 2500 psi. The analyses showed that phase alterations and minor cracking in a microstructure did not affect the design specification for the concrete.

  13. Concrete Durability in Harsh Environmental Conditions Exposed to Freeze Thaw Cycles

    Science.gov (United States)

    Hamze, Youssef

    Under line Pathology of Materials; one of the environmental causes of damage effects on concrete is freeze thaw cycles, which deteriorate the concrete exposed to water in cold weather. An example of old concrete is a dam project that was built in Canada, in the early 1909-1913. This project was reconstructed in 1932, 1934 and 1972, and required renovation due to the ice abrasion with the freeze/thaw cycles. Before completing any renovation, it is required to analyze the structural stability and the concrete failures of this dam. An investigation was conducted to determine the quality of the concrete in the Piers and in the Bridge Deck Slab. It was also required to determine the basic materials' properties that constitute this project. This will improve the analysis of its stability [10]. Core samples were examined and used as test samples, for the Alkali-Silica reactivity test samples, as well as the compressive strength test, the Chloride Ion test, and the freeze thaw testing which was performed on two sets of 12 concrete core samples that were taken from different locations in the project. These locations are the representations of the age of the concrete. Thus, the age difference between the samples' two sets is four decades. Testing was performed on prisms cut from cores. ASTM C-666 procedure (A) was applied using an automatic test system [6]. It was suggested that a plan for renovation of this project should be performed after the analysis is undertaken to assess the conditions estimating the remaining life of the concrete in this project [15].

  14. Analysis of Tools to Evaluate Chloride Threshold for Corrosion Onset of Reinforced Concrete in Tropical Marine Environment of Yucatán, México

    OpenAIRE

    Pedro Castro-Borges; Mercedes Balancán-Zapata; Alexander López-González

    2013-01-01

    The chloride threshold for corrosion onset of reinforced concrete depends on several factors and is only valid for the specific condition of each factor. The main objective of this paper was to analyze different tools to obtain the chloride threshold for corrosion onset of reinforced concrete in tropical marine environment. Sixty Portland cement concrete cylinders were exposed in a tropical marine environment. One half of the samples had a reinforcing bar embedded at the center of the sample ...

  15. Prediction of the curing time to achieve maturity of the nano-cement based concrete using the Weibull distribution model: A complementary data set

    OpenAIRE

    Byung Wan Jo; Sumit Chakraborty; Heon Kim

    2015-01-01

    This data article provides a comparison data for nano-cement based concrete (NCC) and ordinary Portland cement based concrete (OPCC). Concrete samples (OPCC) were fabricated using ten different mix design and their characterization data is provided here. Optimization of curing time using the Weibull distribution model was done by analyzing the rate of change of compressive strength of the OPCC. Initially, the compressive strength of the OPCC samples was measured after completion of four desir...

  16. Self-consolidating concrete homogeneity

    Directory of Open Access Journals (Sweden)

    Jarque, J. C.

    2007-08-01

    Full Text Available Concrete instability may lead to the non-uniform distribution of its properties. The homogeneity of self-consolidating concrete in vertically cast members was therefore explored in this study, analyzing both resistance to segregation and pore structure uniformity. To this end, two series of concretes were prepared, self-consolidating and traditional vibrated materials, with different w/c ratios and types of cement. The results showed that selfconsolidating concretes exhibit high resistance to segregation, albeit slightly lower than found in the traditional mixtures. The pore structure in the former, however, tended to be slightly more uniform, probably as a result of less intense bleeding. Such concretes are also characterized by greater bulk density, lower porosity and smaller mean pore size, which translates into a higher resistance to pressurized water. For pore diameters of over about 0.5 μm, however, the pore size distribution was found to be similar to the distribution in traditional concretes, with similar absorption rates.En este trabajo se estudia la homogeneidad de los hormigones autocompactantes en piezas hormigonadas verticalmente, determinando su resistencia a la segregación y la uniformidad de su estructura porosa, dado que la pérdida de estabilidad de una mezcla puede conducir a una distribución no uniforme de sus propiedades. Para ello se han fabricado dos tipos de hormigones, uno autocompactante y otro tradicional vibrado, con diferentes relaciones a/c y distintos tipos de cemento. Los resultados ponen de manifiesto que los hormigones autocompactantes presentan una buena resistencia a la segregación, aunque algo menor que la registrada en los hormigones tradicionales. A pesar de ello, su estructura porosa tiende a ser ligeramente más uniforme, debido probablemente a un menor sangrado. Asimismo, presentan una mayor densidad aparente, una menor porosidad y un menor tamaño medio de poro, lo que les confiere mejores

  17. 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.

  18. INVESTIGATION OF CURE EFFECT IN HYBRID USE OF GFRP BOX PROFILES WITH CONCRETE

    OpenAIRE

    Aydin, Ferhat; SARIBIYIK, Mehmet

    2011-01-01

    In this study, concrete, which has high compressive strength, with Glass Fiber Reinforced Plastic (GFRP) box profiles that have high tensile strength, have been used as a hybrid materials and experimental study have been carried out to investigate the curing effects. In the experimental study, part of the fresh concrete is filled into the plywood mould and the other part of the concrete is filled into the GFRP box profiles. Part of the samples, which formed in wooden mould, are put into the c...

  19. Water Permeability of Pervious Concrete Is Dependent on the Applied Pressure and Testing Methods

    Directory of Open Access Journals (Sweden)

    Yinghong Qin

    2015-01-01

    Full Text Available Falling head method (FHM and constant head method (CHM are, respectively, used to test the water permeability of permeable concrete, using different water heads on the testing samples. The results indicate the apparent permeability of pervious concrete decreasing with the applied water head. The results also demonstrate the permeability measured from the FHM is lower than that from the CHM. The fundamental difference between the CHM and FHM is examined from the theory of fluid flowing through porous media. The testing results suggest that the water permeability of permeable concrete should be reported with the applied pressure and the associated testing method.

  20. Examples of feedback, experimental and theoretical approaches for concrete durability assessment

    Directory of Open Access Journals (Sweden)

    Toutlemonde F.

    2011-04-01

    Full Text Available This paper presents some experimental data obtained from UHPFRC (Ultra-High Performance Fibre-Reinforced Concrete being exposed for 10 years in a cooling tower and a high slag content concrete being exposed for 30 years in a marine environment. Experimental data are then used for assessing concrete durability through a theoretical approach, namely performance-based analysis. The results from the application of this approach are consistent with the penetration depth of aggressive agents measured from core samples. Finally a simulation method currently being developed by EDF is presented, which has great relevance to durability assessment.

  1. Research on factors influencing radon exhalation rate on aerated concrete block

    International Nuclear Information System (INIS)

    The research was carried out on the variation of the radon exhalation rate of aerated concrete block with the water content and dimension by using the RAD7 radon monitor and the radon exhalation rate test cabin of building materials. The result indicates that the amount of the same samples has no influence on the samples' radon exhalation; if the volume of the aerated concrete block in the test cabin is unchanged and the surface area increases, the radon exhalation rate decreases, but the total of the radon exhaling from the surface of the aerated concrete block keeps constant; for the aerated concrete block, its radon exhalation rate increases with water content as logarithmic growth. (authors)

  2. Effects of composition and exposure on the solar reflectance of Portland cement concrete

    Energy Technology Data Exchange (ETDEWEB)

    Levinson, Ronnen; Akbari, Hashem

    2001-12-21

    Increasing the solar reflectance (albedo) of a paved surface keeps it cooler in the sun, reducing convection of heat from pavement to air and thereby decreasing the ambient air temperature. Simulations of the influence of pavement albedo on air temperature in Los Angeles predict that increasing the albedo of 1,250 km2 of pavement by 0.25 would save cooling energy worth $15M yr-1, and reduce smog-related medical and lost-work expenses by $76M yr-1. Most sidewalks and a small fraction of roads and parking areas are paved with portland cement concrete, which can be made quite reflective through suitable choice of cement and aggregate. Variations with composition and environmental exposure of the albedos of portland cement concrete pavements were investigated through laboratory fabrication and exposure of 32 mixes of concrete. Twenty-four mixes yielded substandard, ''rough'' concretes due to high, unmet aggregate water demand. The albedos of the remaining eight ''smooth'' concrete mixes ranged from 0.41 to 0.77 (mean 0.59). Simulated weathering, soiling, and abrasion each reduced average concrete albedo (mean decreases 0.06, 0.05, and 0.19, respectively), though some samples became slightly more reflective through weathering or soiling. Simulated rain (wetting) strongly depressed the albedos of concretes (mean decrease 0.23) until their surfaces were dried. Concrete albedo grew as the cement hydration reaction progressed (mean increase 0.08), but stabilized within six weeks of casting. White-cement concretes were on average significantly more reflective than gray-cement concretes. The albedo of the most-reflective white-cement concrete was 0.18 to 0.39 higher than that of the most-reflective gray-cement concrete, depending on state of exposure. Concrete albedo generally correlated with cement albedo and sand albedo, and, after abrasion, with rock albedo. Cement albedo had a disproportionately strong influence on the reflectance

  3. Influences of Fly Ash on Concrete Product's Properties and Environmental Impact Reduction

    Directory of Open Access Journals (Sweden)

    Thipsuree Kornboonraksa

    2015-01-01

    Full Text Available This research aimed to study effects of incorporating fly ash into concrete products. Scope of this study were (1 hazard identification of fly ash (2 study on standard testing of various concrete products and (3 study on environmental impact assessment of concrete products mixed with fly ash. Various types of fly ash namely A, B, C and D were sampling from different power plants. Hazard identification of fly ash was analyzed in terms of total threshold limit concentration (TTLC and soluble threshold limit concentration (STLC. It was found that concentrations of chromium, cadmium, lead, mercury, nickel, zinc, copper and arsenic passed the criteria of notification of the ministry of industry regarding disposal of wastes or unusable materials B.E. 2548 (2005 in appendix-2.Three types of concrete products namely brick road, concrete block and ready mixed concrete were studied. Fly ash was used as cementitious materials to replace Portland cement at 10% and 30% mixture. Concrete products with proportion of fly ash showed lower compressive strengths during 28 days of curing times. However, increase of curing times showed higher compressive strengths for all types of concrete products. ANOVA analysis showed that different fly ash proportion and curing times had a significant effect on compressive strength. The method of CML2 baseline 2000, SimaPro 7.3 was used in environmental impact assessment. The functional unit was set up through working area of 1 m3. It was found that concrete products mixed with fly ash showed lower environmental impact compared to concrete products without fly ash. Increasing proportion of fly ash showed decreased environmental impact. From ANOVA analysis, there was no significant effect of fly ash types on environmental impact reduction for all types of concrete products. However, % fly ash mixture showed significant effect on environmental impact reduction especially in terms of global warming. Decrease in global warming (GW

  4. Designing of concrete diamond sawblade

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shao-he; DING Xin-yu; ZHOU Jia-xiang

    2005-01-01

    By analyzing the abrasive theory of concrete diamond sawblade, the proposal that the diamond should be selected by its function in cutting concrete is presented. The part of the big grit diamonds cut rock, and the part of the small grit diamonds improve the wearability of the matrix. The contrast tests are done with different shapes of sawbaldes in split segment, slant "U" slot segment, sandwich segment, turbo segment and three-slot segment. The special shapes of sawblades can improve the effect of cooling and the removing ability of the rock powder. The data of tests show that the efficiency of cutting and the life of sawblades are improved by designing the diamond prescription and using the especial geometry of segment.

  5. Radionuclide Retention in Concrete Wasteforms

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-09-30

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

  6. Introduction to concrete curing effect on the early performance of modern concrete

    Directory of Open Access Journals (Sweden)

    Xiaoxia Zhai

    2015-08-01

    Full Text Available In order to meet the requirements of the modern structure of concrete performance, the composition of modern concrete produced bigger change, this inevitably made an impact on the other properties of concrete. Especially the change of cement fineness and composition, a large number of add mineral admixtures, and the widespread use of high efficiency water reducing agent, has a great influence on the early performance of concrete, especially on the early shrinkage performance, which affect the early cracking of concrete. By collecting and analysising relevant test result, The article summarizes the characteristics of the early performance of modern concrete and their requirements of early curing environment.

  7. Effect of Silica Fume on two-stage Concrete Strength

    Science.gov (United States)

    Abdelgader, H. S.; El-Baden, A. S.

    2015-11-01

    Two-stage concrete (TSC) is an innovative concrete that does not require vibration for placing and compaction. TSC is a simple concept; it is made using the same basic constituents as traditional concrete: cement, coarse aggregate, sand and water as well as mineral and chemical admixtures. As its name suggests, it is produced through a two-stage process. Firstly washed coarse aggregate is placed into the formwork in-situ. Later a specifically designed self compacting grout is introduced into the form from the lowest point under gravity pressure to fill the voids, cementing the aggregate into a monolith. The hardened concrete is dense, homogeneous and has in general improved engineering properties and durability. This paper presents the results from a research work attempt to study the effect of silica fume (SF) and superplasticizers admixtures (SP) on compressive and tensile strength of TSC using various combinations of water to cement ratio (w/c) and cement to sand ratio (c/s). Thirty six concrete mixes with different grout constituents were tested. From each mix twenty four standard cylinder samples of size (150mm×300mm) of concrete containing crushed aggregate were produced. The tested samples were made from combinations of w/c equal to: 0.45, 0.55 and 0.85, and three c/s of values: 0.5, 1 and 1.5. Silica fume was added at a dosage of 6% of weight of cement, while superplasticizer was added at a dosage of 2% of cement weight. Results indicated that both tensile and compressive strength of TSC can be statistically derived as a function of w/c and c/s with good correlation coefficients. The basic principle of traditional concrete, which says that an increase in water/cement ratio will lead to a reduction in compressive strength, was shown to hold true for TSC specimens tested. Using a combination of both silica fume and superplasticisers caused a significant increase in strength relative to control mixes.

  8. Viscoelastic behavior of concrete pile

    Institute of Scientific and Technical Information of China (English)

    丁科; 唐小弟

    2008-01-01

    Based on constitutive theory of viscoelasticity,the viscoelastic behaviour of concrete pile was investigated.The influence of viscosity coefficient on the stress,displacement and velocity response was discussed.With the increase of viscosity coefficient,the amplitude of stress wave decreases,and the maximum value of the stress wave shifts to deeper position of the pile.In other words,the viscosity coefficient behaves as lag effect to stress wave.

  9. Severe ASR damaged concrete bridges

    DEFF Research Database (Denmark)

    Antonio Barbosa, Ricardo; Gustenhoff Hansen, Søren

    2015-01-01

    Technical University of Denmark (DTU) and University of Southern Denmark (SDU) have conducted several full-scale experiments with severe ASR deteriorated bridges. This paper presents few and preliminary results from both the shear tests and the measuring of the material properties. The shear tests...... show that the shear capacity is almost unaffected of ASR despite significant reduction in compressive concrete strength. Furthermore, measurements show a significant tensile reinforcement strain developed due to ASR expansion....

  10. Resonance Testing of Asphalt Concrete

    OpenAIRE

    Gudmarsson, Anders

    2014-01-01

    This thesis present novel non-destructive laboratory test methods to characterize asphalt concrete. The testing is based on frequency response measurements of specimens where resonance frequencies play a key role to derive material properties such as the complex modulus and complex Poisson’s ratio. These material properties are directly related to pavement quality and used in thickness design of pavements. Since conventional cyclic loading is expensive, time consuming and complicated to perfo...

  11. Carbonation of concrete structures located in urban and rural environment

    Directory of Open Access Journals (Sweden)

    C. Priano

    2013-01-01

    Full Text Available The objective of this investigation was to study the effect of carbonation on two reinforced concrete structures of 42 and 60 years old, located on two different environments: urban and rural. Samples of concrete were taken, the carbonation depth was measured and density, absorption and porosity tests were performed. The carbonation process can be modeled by the equation of the square root of time. From that model, the carbonation constant for each sample was calculated, the progress of the carbonation depth versus time was plotted and the correlation between porosity and depth of carbonation was analyzed. It was verified the existence of different microclimates surrounding structural elements. The moisture content of the surrounding surface of each structural element is the most important factor affecting the progress of carbonation.

  12. Research in nondestructive evaluation techniques for nuclear reactor concrete structures

    Science.gov (United States)

    Clayton, Dwight; Smith, Cyrus

    2014-02-01

    The purpose of the Materials Aging and Degradation (MAaD) Pathway of the Department of Energy's Light Water Reactor Sustainability (LWRS) Program is to develop the scientific basis for understanding and predicting longterm environmental degradation behavior of material in nuclear power plants and to provide data and methods to assess the performance of systems, structures, and components (SSCs) essential to safe and sustained nuclear power plant operations. The understanding of aging-related phenomena and their impacts on SSCs is expected to be a significant issue for any nuclear power plant planning for long-term operations (i.e. service beyond the initial license renewal period). Management of those phenomena and their impacts during long-term operations can be better enable by improved methods and techniques for detection, monitoring, and prediction of SSC degradation. The MAaD Pathway R&D Roadmap for Concrete, "Light Water Reactor Sustainability Nondestructive Evaluation for Concrete Research and Development Roadmap", focused initial research efforts on understanding the recent concrete issues at nuclear power plants and identifying the availability of concrete samples for NDE techniques evaluation and testing. [1] An overview of the research performed by ORNL in these two areas is presented here.

  13. Radiolytic gas production from concrete containing Savannah River Plant waste

    International Nuclear Information System (INIS)

    To determine the extent of gas production from radiolysis of concrete containing radioactive Savannah River Plant waste, samples of concrete and simulated waste were irradiated by 60Co gamma rays and 244Cm alpha particles. Gamma radiolysis simulated radiolysis by beta particles from fission products in the waste. Alpha radiolysis indicated the effect of alpha particles from transuranic isotopes in the waste. With gamma radiolysis, hydrogen was the only significant product; hydrogen reached a steady-state pressure that increased with increasing radiation intensity. Hydrogen was produced faster, and a higher steady-state pressure resulted when an organic set retarder was present. Oxygen that was sealed with the wastes was depleted. Gamma radiolysis also produced nitrous oxide gas when nitrate or nitrite was present in the concrete. With alpha radiolysis, hydrogen and oxygen were produced. Hydrogen did not reach a steady-state pressure at 137Cs and 90Sr), hydrogen will reach a steady-state pressure of 8 to 28 psi, and oxygen will be partially consumed. These predictions were confirmed by measurement of gas produced over a short time in a container of concrete and actual SRP waste. The tests with simulated waste also indicated that nitrous oxide may form, but because of the low nitrate or nitrite content of the waste, the maximum pressure of nitrous oxide after 300 years will be 238Pu and 239Pu will predominate; the hydrogen and oxygen pressures will increase to >200 psi

  14. Interaction of low pH cementitious concretes with groundwaters

    International Nuclear Information System (INIS)

    Some engineering construction concepts for high level radioactive waste underground repositories consider the use of a bentonite barrier in contact with cementitious materials with a pore fluid pH value inferior or equal to 11 (based on low-pH cements) to maintain the bentonite stability. The research on low-pH cementitious materials is mainly addressed from two different approaches, one with Calcium Silicate Cements (OPC, Ordinary Portland Cement based), the other with Calcium Aluminates Cements (CAC based). The use of these both types of cements (OPC based or CAC based) implies the use of high mineral additions contents in the binder that should significantly modify most of the concrete 'standard' properties. Taking into account the long life expected in this type of repositories, parameters related to the durability of the low-pH concretes must be analyzed. This work shows some recent studies that deal with the evaluation of the resistance of low-pH concretes to long term groundwater aggression. After a presentation of the accelerated leaching test (based on a percolation method), results are given for the characterization of the leaching solution evolution and the evaluation of the modifications generated in the solid phases. Results show that the low-pH concretes evaluated have good resistance against groundwater interaction, although an altered front can be observed from the surface in all the tested samples

  15. Neutron scattering techniques in the examination of recycled aggregate concrete

    International Nuclear Information System (INIS)

    Full text: Researchers at Swinburne University of Technology (SUT) have undertaken a research project aiming initially at better understanding the effects of any chemical impurities in Recycled Concrete Aggregate (RCA) on the microstructure development of Recycled Aggregate Concrete (RAC). Furthermore, a porosity of RCA and RAC and its effect on the acoustic performance and mechanical properties is being investigated. A number of conventional tests have been employed to examine the porosity of the aggregate and concrete made from RCA ranging from Volume of Permeable Voids test, through nitrogen adsorption to scanning electron microscopy. These tests are performed at SUT to characterise pores structure including pore size and volume as well as their surface area. The preparation of samples differs for the various tests, and this is a main reason contributing to inconsistencies in the results from these tests. None-the-less the results indicate strong positive correlation of inherent and purposely introduced porosity in RAC to its sound absorption capacities. Some inconsistency in the results is also due to the complexity of concrete itself compounded by the use of recycled material. However, the research has been granted a Grant from Australian Institute of Nuclear Science and Engineering (AINSE) which allows to conduct RAC examination using Small Angle Neutron Scattering (SANS). This neutron scattering technique characterises pore structure in a non-destructive manner. The results from this method should augment these obtained from conventional methods

  16. Very heavy iron-punching concretes

    International Nuclear Information System (INIS)

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

  17. Experimental Studies on Glass Fiber Concrete

    Directory of Open Access Journals (Sweden)

    J.D.Chaitanya kumar

    2016-06-01

    Full Text Available Concrete is one of the most widely recognized development material for the most part delivered by utilizing locally accessible ingredients. The development of concrete has brought about the essential need for additives both chemical and mineral to improve the performance of concrete. Hence varieties of admixtures such as fly ash, coconut fibre have been used so far. Hence an attempt has been made in the present investigation to study the behaviour of glass fibre in concrete. The present trend in concrete technology is towards increasing the strength and durability of concrete to meet the demands of the modern construction. The main aim of the study is to study the effect of glass fibre in the concrete. Glass fibre has the high tensile strength and fire resistant properties thus reducing the loss of damage during fire accidents. The addition of these fibres into concrete can dramatically increase the compressive strength, tensile strength and split tensile strength of the concrete. In this study, tests have done for the concrete with glass fibre of 0.5%, 1%, 2% and 3% of cement by adding as an admixture

  18. Addressing concrete cracking in NPPs

    International Nuclear Information System (INIS)

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

  19. Cement and concrete options paper

    International Nuclear Information System (INIS)

    Greenhouse gas emissions associated with the production of concrete are projected to increase from 10.5 million tonnes in 1990 to almost 14 million tonnes in 2010. Over half of this amount will be non-energy related emissions of carbon dioxide resulting from the conversion of limestone to lime. According to this report by industry experts, the industry has an excellent record of improving energy efficiency and there are few easy gains remaining. Nevertheless, improvements in energy efficiency and fuel use, increased use of concrete where it can be shown to result in net reduction of GHG emissions, and partial replacement of cement by supplementary cementitious materials that involve no additional generation of GHGs, could yield an approximate reduction in carbon dioxide emissions of nearly seven million tons in 2010. The industry proposes three measures to realise these benefits: (1) encouraging replacement of fossil fuels by otherwise waste material, (2) encouraging increased use of concrete in constructing houses and roads, and (3) encouraging increased use of supplementary cementing materials. The industry is opposed to carbon or energy taxes that increase the cost of doing business, on the grounds that such taxes would adversely affect the industry's competitive position internationally. tabs

  20. Study of some health physics parameters of bismuth-ground granulated blast furnace slag shielding concretes

    Science.gov (United States)

    Kumar, Sandeep; Singh, Sukhpal

    2016-05-01

    The Bismuth-ground granulated blastfurnace slang (Bi-GGBFS) concrete samples were prepared. The weight percentage of different elements present inBi-GGBFS Shielding concretewas evaluated by Energy Dispersive X-ray Microanalysis (EDX). The exposure rate and absorbed dose rate characteristics were calculated theoretically for radioactive sources namely 241Am and 137Cs. Our calculations reveal that the Bi-GGBFS concretes are effective in shielding material for gamma radiations.

  1. Water Permeability of Pervious Concrete Is Dependent on the Applied Pressure and Testing Methods

    OpenAIRE

    Yinghong Qin; Haifeng Yang; Zhiheng Deng; Jiang He

    2015-01-01

    Falling head method (FHM) and constant head method (CHM) are, respectively, used to test the water permeability of permeable concrete, using different water heads on the testing samples. The results indicate the apparent permeability of pervious concrete decreasing with the applied water head. The results also demonstrate the permeability measured from the FHM is lower than that from the CHM. The fundamental difference between the CHM and FHM is examined from the theory of fluid flowing throu...

  2. Effects of fly ash fineness on the mechanical properties of concrete

    Indian Academy of Sciences (India)

    Şemsi Yazici; Hasan Şahan Arel

    2012-06-01

    The present study reviews the effects of fly ash fineness on the compressive and splitting tensile strength of the concretes. A fly ash of lignite origin with Blaine fineness of 2351 cm2/g was ground in a ball mill. As a consequence of the grinding process, fly ashes with fineness of 3849 cm2/g and 5239 cm2/g were obtained. Fly ashes with three different fineness were used instead of cement of 0%, 5%, 10%, and 15% and ten different types of concrete mixture were produced. In the concrete mixtures, the dosage of binder and water/cement ratio were fixed at 350 kg/m3 and 0.50, respectively. Slump values for the concretes were adjusted to be 100 ± 20 mm. Cubic samples were cast with edges of 100 mm. The specimens were cured in water at 20° C. At the end of curing process, compressive and splitting tensile strengths of the concrete samples were determined at 7, 28, 56, 90, 120 and 180 days. It was observed that compressive and splitting tensile strength of the concretes was affected by fineness of fly ash in short-and long-terms. It was found that compressive and tensile strength of the concretes increased as fly ash fineness increased. It was concluded that Blaine fineness value should be above 3849 cm2/g fineness of fly ash to have positive impact on mechanical properties of concrete. The effects of fly ash fineness on the compressive and splitting tensile strength of the concretes were remarkably seen in the fly ash with FAC code with fineness of 5235 cm2/g.

  3. Characterization of concrete from Roman theatre and amphitheater in Emerita Augusta (Mérida, Spain)

    Science.gov (United States)

    Mota-Lopez, Maria Isabel; Fort, Rafael; Alvarez de Buergo, Monica; Pizzo, Antonio; Maderuelo-Sanz, Ruben; Meneses-Rodríguez, Juan Miguel

    2016-04-01

    The restoration of historical buildings is very important for the history and culture of the cities and their population. It requires an advanced knowledge of the building materials used for the construction of these structures. Previously to any intervention in historical buildings, it is necessary a historic-scientific study of the original material. Historic mortars or concretes can reveal us different composition and the dependence on the geographical location and the time period of its construction. Historical concretes are complex systems that contain aerial or hydraulic binders or a blend of them, with aggregates, not always crystalline, and others elements that interact with the binder. The use of different techniques for microstructural characterization of materials, like optical microscopy, X-ray diffractometry or petrophysical analysis, allows the determination of the composition and some properties of these concretes. However, each technique has its own limits and, in many cases, several characterization techniques must be used to obtain coherent and reliable results. The present study focuses on the compositional characterization of Roman concrete from Roman buildings for public spectacles of Emerita Augusta, Mérida, Spain. An advanced knowledge of the Roman concrete composition is required to get a reliable restoration and preservation of these ancient monuments. Various samples of concrete were extracted from different zones from this archaeological site. The concrete was studied through mineralogical analysis (petrographic microscope and XRD) and petrophysical properties determination (bulk and real density, open porosity, mercury porosimetry intrusion, compressive strength and Ultrasound propagation velocity). The results obtained allow us to know the original composition of the concrete and the provenance of the aggregates used in it. Acknowledgements: Community of Madrid for financing Geomateriales2 program (P2013/MIT2914), to the funding

  4. Evaluation of radionuclide penetration of structural concrete surfaces in the Three Mile Island Unit 2 reactor building

    International Nuclear Information System (INIS)

    The March 28, 1979 loss-of-coolant accident at Three Mile Island Unit 2 (TMI-2) resulted in the exposure of ∼3000 m2 of reactor building internal concrete surfaces to both liquid-and vapor-borne contaminants. The period of contact between the major structural concrete surfaces and the aqueous solutions of mixed fission products ranged from a few days to several years. Exclusive of the reactor building basement impingement walls above a height of 1.6 m, all concrete surfaces were protected with an epoxy-based coating. This coating provides a tough, easily decontaminated surface for the concrete during normal operation and maintenance cycles. At the completion of the gross decontamination of the accessible reactor building elevations in 1982, exposure rates remained elevated above expected levels as indicated by early decontamination factors. Exposure rate measurements and small-scale scarification samples of the reactor building surfaces demonstrated that the protective coatings and concrete in the reactor building had absorbed radionuclides, thereby creating a large fixed source. In September 1983, a concrete core sampling program was conducted in the TMI-2 reactor building to assess the depth of contaminant penetration into the coatings and concrete on elevations 93m and 106 m. Sampling of the reactor building basement concrete surfaces [elevation 86 m] was deferred until 1985 and 1986 to provide lead time for remote systems development

  5. Long-Term Field Performance of Pervious Concrete Pavement

    OpenAIRE

    Aleksandra Radlińska; Andrea Welker; Kathryn Greising; Blake Campbell; David Littlewood

    2012-01-01

    The work described in this paper provides an evaluation of an aged pervious concrete pavement in the Northeastern United States to provide a better understanding of the long-lasting effects of placement techniques as well as the long-term field performance of porous pavement, specifically in areas susceptible to freezing and thawing. Multiple samples were taken from the existing pavement and were examined in terms of porosity and unit weight, compressive and splitting tensile strength, and th...

  6. CONCRETE DURABILITY Through High Volume Fly ash Concrete (HVFC A Literature review

    Directory of Open Access Journals (Sweden)

    VANITA AGGARWAL

    2010-09-01

    Full Text Available The application of concrete in construction is as old as the days of Greek and roman civilization. But for numerous easons, the concrete construction industry is not sustainable. It consumes a lot of virgin materials and the principal raw material of concrete i.e. cement is responsible for green house gas emissions causing a threat to environment through global warming. Therefore, the industry has seen various types of concrete in search of a solution to sustainable development. Infrastructural growth has witnessed many forms of concrete like High Strength Concrete, High Performance Concrete, Self Compacting Concrete and the latest in the series is High Volume Fly Ash Concrete (HVFC. The paradigm has shifted from one property to other of concrete with advancement in technology. The construction techniques have been modernized with focus on high strength, dense and uniform surface texture, more reliable quality, improved durability and faster construction. This paper discusses the development of high volume fly ash concrete for construction with reference to its predecessors like HSC and HPC. The literature available on use of fly ash in concrete has been extensively searched for getting a platform for the start of research on use of high volumes of fly ash in concrete pavements.

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

    International Nuclear Information System (INIS)

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

  8. Photocatalytic activity of titanium dioxide modified concrete materials - influence of utilizing recycled glass cullets as aggregates.

    Science.gov (United States)

    Chen, Jun; Poon, Chi-Sun

    2009-08-01

    Combining the use of photocatalysts with cementitious materials is an important development in the field of photocatalytic air pollution mitigation. This paper presents the results of a systematic study on assessing the effectiveness of pollutant degradation by concrete surface layers that incorporate a photocatalytic material - Titanium Dioxide. The photocatalytic activity of the concrete samples was determined by photocatalytic oxidation of nitric oxide (NO) in the laboratory. Recycled glass cullets, derived from crushed waste beverage bottles, were used to replace sand in preparing the concrete surface layers. Factors, which may affect the pollutant removal performance of the concrete layers including glass color, aggregate size and curing age, were investigated. The results show a significant enhancement of the photocatalytic activity due to the use of glass cullets as aggregates in the concrete layers. The samples fabricated with clear glass cullets exhibited threefold NO removal efficiency compared to the samples fabricated with river sand. The light transmittance property of glass was postulated to account for the efficiency improvement, which was confirmed by a separate simulation study. But the influence of the size of glass cullets was not evident. In addition, the photocatalytic activity of concrete surface layers decreased with curing age, showing a loss of 20% photocatalytic activity after 56-day curing. PMID:19540649

  9. Durability of cracked fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place

    fibre reinforcement are exposed to a combination of mechanical and environmental load to indicate whether fibre reinforcement will improve the durability of cracked concrete structures. Secondly, it is the aim to identify important mechanisms for the effect of the fibre reinforcement on the durability......Durability studies are carried out at BKM as part of the research project "Design Methods for Fibre Reinforced Concrete" (FRC) involving BKM, The Concrete Research Center at DTI, Building Technology at Aalborg University, Rambøll, 4K-Beton and Rasmussen & Schiøtz. Concrete beams with or without...... pore structure are made on specimens drilled or sawed from beams after unloading (mechanical load). The pore structure of the concretes will be studied by microscopy, sorption and suction curves. The test programme involves three different concrete qualities (water-cement ratios). Both steel fibres (ZP...

  10. Transitional Thermal Creep of Early Age Concrete

    DEFF Research Database (Denmark)

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

    1999-01-01

    Couplings between creep of hardened concrete and temperature/water effects are well-known. Both the level and the gradients in time of temperature or water content influence the creep properties. In early age concrete the internal drying and the heat development due to hydration increase the effect...... of these couplings. The purpose of this work is to set up a mathematical model for creep of concrete which includes the transitional thermal effect. The model govern both early age concrete and hardened concrete. The development of the material properties in the model are assumed to depend on the...... imbalance in the microstructure termed the microprestresses, which reduces the stiffness of the concrete and increase the creep rate. The aging material is modelled in an incremental way reflecting the hydration process in which new layers of cement gel solidifies in a stress free state and add stiffness to...

  11. Transitional Thermal Creep of Early Age Concrete

    DEFF Research Database (Denmark)

    Hauggaard, A. B.; Damkilde, L.; Hansen, Per Freiesleben

    1999-01-01

    Couplings between creep of hardened concrete and temperature/water effects are well-known. Both the level and the gradients in time of temperature or water content influence the creep properties. In early age concrete the internal drying and the heat development due to hydration increase the effect...... of these couplings. The purpose of this work is to set up a mathematical model for creep of concrete that includes the transitional thermal effect. The model governs both early age concrete and hardened concrete. The development of the material properties in the model is assumed to depend on the...... imbalance in the microstructure termed the microprestresses, which reduce the stiffness of the concrete and increase the creep rate. The aging material is modeled in an incremental way reflecting the hydration process in which new layers of cement gel solidify in a stress free state and add stiffness to the...

  12. Rotational Capacity of Reinforced Concrete Beams

    DEFF Research Database (Denmark)

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

    1995-01-01

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

  13. Field Studies of Effectiveness of Concrete Repairs

    International Nuclear Information System (INIS)

    This paper presents a summary of the work carried out under an HSE research study entitled 'Field Studies of Effectiveness of Concrete Repairs'. There is little published information describing or comparing the long-term performance of different repair types. This project examines 45 sites where repairs have been carried out and have remained in service for several years and evaluates the effectiveness of a range of concrete repair systems as applied in practice. The sites include a range of structure types, ages and service environments, and include bridges, tunnels, building frames, and car parks in industrial, public, highway and nuclear environments. The repairs include hand and trowel applied materials, sprayed materials, and cathodic protection techniques, and also some sites with coating and crack injection systems. The objective is to improve practices for maintaining and improving the integrity of operational structures and so achieve higher standards of structural safety and reliability and better whole-life structural management. The project employed a range of visual, non-destructive and destructive investigation techniques at repaired sites and compared the condition found with records of the repair procedures and objectives. The site investigations involved detailed visual inspection, and surveys using hammer tapping, cover-meter, half-cell and carbonation depth, pull-off testing and core sampling for petrographic analysis of the repair material, repair layer interfaces and repair/substrate interface. Examination of records of the repairs allowed assessments to be made of the level of understanding of the original cause of deterioration and the need and objectives for the subsequent repairs. Comparisons have been made between the specification and evidence from the repair sites. The owner's repair objectives and constraints, and the quality and effectiveness of the repairs have been considered. The site investigations have provided detailed

  14. Modelling the Loss of Steel-Concrete Bonds in Corroded Reinforced Concrete Beams

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    The existing stochastic models for deterioration of reinforced concrete structures is extended by adding modelling of "loss of bond" due to corrosion between the reinforcement bars and the surrounding concrete....

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

    International Nuclear Information System (INIS)

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

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

    DEFF Research Database (Denmark)

    Ørum, Tania

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

  17. Further development of the hydraulic compensation method for compressive strain measurement in concrete

    International Nuclear Information System (INIS)

    A commercially available stress gauge was selected, thoroughly examined, improved and tested in this article for allowing assessment of buildings by means of strain measurement. Model studies on the systems of concrete/gauge or concrete/sensor, resp., were performed illustrating the system's mode of action and enabling improvements to be carried out in general and in particular on the gauge under study. The system of concrete/sensor was rendered more transparent particularly by the model studies by means of the finite element method and by the model studies with the analog computer suggesting improvements performed later on. Along with the model studies, improvements were obtained by the studies on the selected gauge in the concrete. On the one hand, they allowed a theoretical solution to the problem of the sensor's high-degree temperature dependence, and, on the other hand, examination of the influence of concrete additives on the sensor resulted in the sensor being miniaturized much more, thus reducing the disruptive influence of the foreign body 'sensor' in the concrete. Calculations of and studies on, e.g., the influence of cross-strains to the sensor, the influence of adhesion between sensor and concrete on measurement results and the effects of sample dimensions on test results contributed to secure the results obtained. (orig.)

  18. Leaching studies of heavy concrete material for nuclear fuel waste immobilization containers

    International Nuclear Information System (INIS)

    The leaching behaviour of a high-density concrete was studied as part of a program to evaluate its potential use as a container material for nuclear fuel waste under conditions of deep geologic disposal. Samples of concrete material were leached in deionized distilled water, Standard Canadian Shield Saline Solution (SCSSS), SCSSS plus 20% Na-bentonite, and SCSSS plus granite and 20% Na-bentonite under static conditions at 100 degrees celsius for periods up to 365 days. The results of these leaching experiments suggest that the stability of concrete depends on the possible internal structural changes due to hydration reactions of unhydrated components, leading to the formation of C-S-H gel plus portlandite (Ca(OH)2). The factors controlling the concrete leaching process were the composition of the leachant and the concentration of elements in solution capable of forming precipitates on the concrete surface, e.g., silicon, Mg2+ and Ca2+. The main effect observed during leaching was an increase in groundwater pH (from 7 to 9). However, the addition of Na-bentonite suppressed the normal tendency of the pH of the groundwater in contact with concrete to rise rapidly. It was shown that the solution concentration of elements released from the concrete, particularly potassium, increased in the presence of Na-bentonite

  19. Recycled aggregate concrete exposed to elevated temperature

    OpenAIRE

    Arundeb Gupta; Saroj Mandal; Somnath Ghosh

    2012-01-01

    An experimental investigation has been conducted to study the mechanical as well as micro structural properties of Recycled aggregate concrete (RAC) exposed to elevated temperature. Fly ash (as replacement of cement) was added while making concrete. Recycled aggregates are mixed with natural aggregates also to prepare concrete. Cubes and cylinder test specimens were prepared and cured under water for 28 days. Test specimens were exposed to different levels of temperature (200oC, 400oC, 600oC,...

  20. Elevated temperature concrete curing - using polypropylene fibres

    OpenAIRE

    Richardson, Alan; Coventry, Kathryn; Morgan, Miles

    2011-01-01

    This paper examines cement hydration when concrete cures at elevated temperatures with and without the addition of Type 1 polypropylene fibres and addresses some of the ambiguities that have arisen from previous research. Paired comparison tests were carried out to compare density, strength, pulse velocity, and absorption using plain and fibre concrete at ambient UK indoor temperatures, compared to concrete at elevated temperatures that would be found in The Middle East. The results ...

  1. Compressive Strength of Fibre Reinforced Concrete

    OpenAIRE

    Jelušič, Matjaž

    2009-01-01

    The thesis features an analysis of the time development of compressive strength of fibre reinforced normal and high strength concrete. Concrete mixtures, taken from the doctoral dissertation of assistant Dr Drago Saje, were used as comparable mixtures to fibre reinforced concrete mixtures with different volume shares of fibres. Two types of steel fibres were used, both featuring the same characteristics but having different lengths (16 and 30 mm), as well as polypropylene fibres. The percenta...

  2. Carbonated concrete blocks for CO2 captation

    OpenAIRE

    Courard, Luc; Parmentier, Véronique; Michel, Frédéric

    2015-01-01

    The CO2 captation process called carbonation, improves specific properties of the concrete during the conversion of carbon dioxide CO2 into calcium carbonate CaCO3. Current environmental concerns motivate the study of carbonation in order to maximize the absorption of carbon dioxide. Moreover, lightweight concrete with bio-based products knows an interesting development in the construction field, especially as thermal insulation panels for walls in buildings. Concrete blocks produced with mis...

  3. Utilization of Electronic Waste Plastic in Concrete

    OpenAIRE

    Vivek S. Damal; Saurabh S. Londhe

    2015-01-01

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

  4. Phase 2 microwave concrete decontamination results

    International Nuclear Information System (INIS)

    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 cm2/s and 4.9 cm3/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

  5. Composite structure made of concrete and timber

    OpenAIRE

    Kozjan, Ana

    2009-01-01

    Thesis work is dealing with behavior of composite structure made of concrete and timber. First the scope of the document is introduced following by description of the problem and explaining the purpose and goals. Continuing of the document is presented composite structure concrete-timber. The composite material is described, composite structure is represent, stated are reasons of coupling concrete and timber and the typical connection in composite structure are represented. Thesis describes c...

  6. HYDRAULIC CONCRETE COMPOSITION AND PROPERTIES CONTROL SYSTEM

    OpenAIRE

    O. M. Pshinko; A. V. Krasnyuk; O. V. Hromova

    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...

  7. Bond between concrete and reinforcing steel

    OpenAIRE

    Dežman, Andraž

    2015-01-01

    This thesis researches bond characteristics between the 12mm steel reinforcing bar and various types of concrete. Standard Eurocode 2 and FIB Model Code 2010 define ultimate bond stress, which acts like shear stress around the reinforcing bar. In correlation with bond, high strength concrete is poorly represented, furthermore, research and information on fibre concrete are lacking. Therefore, a series of pull-out tests, based on standard SIST EN 10080:2005, have been conducted....

  8. Chloride migration in concrete with superabsorbent polymers

    OpenAIRE

    Hasholt, Marianne Tange; Jensen, Ole Mejlhede

    2015-01-01

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

  9. Maintenance and Repair of Concrete Structures

    OpenAIRE

    Bijen, J.M.J.M.

    1989-01-01

    In 1987 and 1988 a series of articles was published in the Dutchjournal "Cement" about maintenance and repair of concrete structures. The series was written to promote the transfer of know-how concerning maintenance and repair of concrete structures. Use has been made of know-how developed in the Netherlands. The Centre for Civil Engineering Research, Codes and Specifications, CUR, is performing an extensive research program regarding repair and protection techniques for concrete. After readi...

  10. Durability of high volume fly ash concrete

    OpenAIRE

    Camões, Aires

    2006-01-01

    It is well known that the concrete industry has to contribute to the sustainability of construction. For this intent it is necessary to reduce the cement content without compromising the durability requirements of the concrete constructions. Therefore, large scale cement replacement in concrete by by products such as fly ash will be extremely beneficial from the overall ecological and environmental point of view. In this context, an experimental research work was carried out focused on the...

  11. Efficient strengthening technique for reinforced concrete slabs

    OpenAIRE

    Bonaldo, Everaldo; Barros, Joaquim A. O.; Lourenço, Paulo B.

    2006-01-01

    A promising strengthening strategy, using carbon fiber reinforced polymer (CFRP) materials, consists in applying CFRP laminate strips into pre-cut slits opened in the concrete cover of the elements to strengthen. This strengthening technique is designated by Near Surface Mounted (NSM) and has been successfully used to increase the flexural and the shear resistance of concrete and masonry structures. The present work describes an efficient strategy, using steel fiber reinforced concrete (SFRC)...

  12. Ductility in lightweight concrete with fiber

    OpenAIRE

    Ahmadyar, Milad

    2011-01-01

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

  13. Progress of Carbonation in Chloride Contaminated Concretes

    OpenAIRE

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

    2016-01-01

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

  14. Shrinkage of Concrete using Porous Aggregates

    OpenAIRE

    Valgeir Ó. Flosason 1987

    2014-01-01

    During its service life, concrete undergoes volume changes which can affect quality and durability of the concrete. There are several types of volume changes, but shrinkage is the type of volume change which is often responsible for cracking of the concrete. Shrinkage can be categorized due to several different mechanisms which cause shrinkage. The main types of shrinkage are plastic shrinkage, chemical shrinkage, autogenous shrinkage, drying shrinkage and carbonation shrinkage. In this ma...

  15. HYDRAULIC CONCRETE COMPOSITION AND PROPERTIES CONTROL SYSTEM

    OpenAIRE

    O. M. Pshinko; KRASNYUK A.V.; O. V. Hromova

    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...

  16. DECISION MAKING MODELING OF CONCRETE REQUIREMENTS

    OpenAIRE

    Suhartono Irawan; Harry Patmadjaja; Richard Tanara; Fransisca Soeprajogi

    2001-01-01

    This paper presents the results of an experimental evaluation between predicted and practice concrete strength. The scope of the evaluation is the optimisation of the cement content for different concrete grades as a result of bringing the target mean value of tests cubes closer to the required characteristic strength value by reducing the standard deviation. Abstract in Bahasa Indonesia : concrete+mix+design%2C+acceptance+control%2C+optimisation%2C+cement+content.

  17. DECISION MAKING MODELING OF CONCRETE REQUIREMENTS

    Directory of Open Access Journals (Sweden)

    Suhartono Irawan

    2001-01-01

    Full Text Available This paper presents the results of an experimental evaluation between predicted and practice concrete strength. The scope of the evaluation is the optimisation of the cement content for different concrete grades as a result of bringing the target mean value of tests cubes closer to the required characteristic strength value by reducing the standard deviation. Abstract in Bahasa Indonesia : concrete+mix+design%2C+acceptance+control%2C+optimisation%2C+cement+content.

  18. Reliable concrete repair: A critical review

    OpenAIRE

    Lukovic, M.; Ye, G.; Breugel, K. van

    2012-01-01

    This paper highlights the importance of achieving durable and long-term predictable repair of reinforced concrete structures. The performance of concrete repair in past and current engineering practice, including all types of repair and application of different materials, is often unsatisfactory. One of the reasons for this lays in the fact that knowledge regarding bonding mechanism and bond properties at the interface of repair material and concrete substrate is still lacking. This paper int...

  19. Application of diamond tools when decontaminating concrete

    International Nuclear Information System (INIS)

    The utilization of diamond concrete cutting tools offers new potential approaches to the recurring problems of removing contaminated concrete. Innovative techniques can provide exacting removal within a dust-free environment. Present day technology allows remote control operated equipment to perform tasks heretofore considered impossible. Experience gained from years of removing concrete within the construction industry hopefully can contribute new and improved methods to D and D projects

  20. Properties of concrete containing used engine oil

    OpenAIRE

    Nasir Shafiq; Muhd Fadhil Nuruddin; Salmia Beddu

    2011-01-01

    Since last few years cement replacement materials, industrial by-products and agricultural wastes in concrete production are widely used. It imparts positive environmental effect because the waste materials are not released to the environment. It was reported that the leakage of motor oil onto concrete surfaces in old grinding units increased the resistance such concrete to freezing and thawing, it made to understand that the effect is similar to adding an air-entraining chemical admixture to...

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

    OpenAIRE

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

    2011-01-01

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

  2. Structural Concrete Prepared with Coarse Recycled Concrete Aggregate: From Investigation to Design

    OpenAIRE

    Valeria Corinaldesi

    2011-01-01

    An investigation of mechanical behaviour and elastic properties of recycled aggregate concrete (RAC) is presented. RACs were prepared by using a coarse aggregate fraction made of recycled concrete coming from a recycling plant in which rubble from concrete structure demolition is collected and suitably treated. Several concrete mixtures were prepared by using either the only virgin aggregates (as reference) or 30% coarse recycled aggregate replacing gravel and by using two different kinds of ...

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

    OpenAIRE

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

    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 ...

  4. Experimental Study on Torsion of Steel Fiber Reinforced Concrete Members with Ternary Blended Concrete

    OpenAIRE

    Omer Zaheer Ahmed; Mohd Zaker

    2014-01-01

    The study on the torsional behavior of concrete in which the effect of fiber reinforcement in resisting twisting of concrete beams and performance of concrete with ternary blends. When silica fume is added to fresh concrete it chemically reacts with the CH gel to produces additional CSH gel. The benefit of this reaction is twofold increased compressive strength and chemical resistance. The hydration (mixing with water) of Portland cement produces many compounds, including calcium ...

  5. Influence of added concrete compressive strength on adhesion to an existing concrete substrate

    OpenAIRE

    Júlio, Eduardo N. B. S.; Branco, Fernando A. B.; Silva, Vítor D.; Lourenço, Jorge F.

    2006-01-01

    An experimental study was performed to evaluate the bond strength between two concrete layers of different ages, considering different mixtures of added concrete, with different strengths. The specimens first had the roughness of the substrate surface increased by sand blasting. Later, the new concrete was added. Afterwards, slant shear tests were performed to quantify the bond strength in shear. These tests indicated that increasing the compressive strength of the added concrete relative to ...

  6. Porous Network Concrete: a bio-inspired building component to make concrete structures self-healing

    OpenAIRE

    Sangadji, S.

    2015-01-01

    The high energy consumption, its corresponding emission of CO2 and financial losses due to premature failure are the pressing sustainability issues which must be tackled by the concrete infrastructure industry. Enhancement of concrete materials and durability of structures (designing new infrastructures for longer service life) is one solution to overcome the dilemma. Concrete is a quasi-brittle material with properties that are high in compression but weak in tension, therefor concrete is pr...

  7. CONCRETE DURABILITY Through High Volume Fly ash Concrete (HVFC) A Literature review

    OpenAIRE

    VANITA AGGARWAL; Dr. S.M.GUPTA; Dr.S.N.SACHDE

    2010-01-01

    The application of concrete in construction is as old as the days of Greek and roman civilization. But for numerous easons, the concrete construction industry is not sustainable. It consumes a lot of virgin materials and the principal raw material of concrete i.e. cement is responsible for green house gas emissions causing a threat to environment through global warming. Therefore, the industry has seen various types of concrete in search of a solution to sustainable development. Infrastructur...

  8. Introduction to concrete curing effect on the early performance of modern concrete

    OpenAIRE

    Xiaoxia Zhai

    2015-01-01

    In order to meet the requirements of the modern structure of concrete performance, the composition of modern concrete produced bigger change, this inevitably made an impact on the other properties of concrete. Especially the change of cement fineness and composition, a large number of add mineral admixtures, and the widespread use of high efficiency water reducing agent, has a great influence on the early performance of concrete, especially on the early shrinkage performance, whic...

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

    International Nuclear Information System (INIS)

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

  10. Economic analysis of recycling contaminated concrete

    Energy Technology Data Exchange (ETDEWEB)

    Stephen, A.; Ayers, K.W.; Boren, J.K.; Parker, F.L. [Vanderbilt Univ., Nashville, TN (United States)

    1997-02-01

    Decontamination and Decommissioning activities in the DOE complex generate large volumes of radioactively contaminated and uncontaminated concrete. Currently, this concrete is usually decontaminated, the contaminated waste is disposed of in a LLW facility and the decontaminated concrete is placed in C&D landfills. A number of alternatives to this practice are available including recycling of the concrete. Cost estimates for six alternatives were developed using a spreadsheet model. The results of this analysis show that recycling alternatives are at least as economical as current practice.

  11. Applications and Properties of Fibre Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Amit Rai1 ,

    2014-05-01

    Full Text Available In conventional concrete, micro-cracks develop before structure is loaded because of drying shrinkage and other causes of volume change. When the structure is loaded, the micro cracks open up and propagate because of development of such micro-cracks, results in inelastic deformation in concrete. Fibre reinforced concrete (FRC is cementing concrete reinforced mixture with more or less randomly distributed small fibres. In the FRC, a numbers of small fibres are dispersed and distributed randomly in the concrete at the time of mixing, and thus improve concrete properties in all directions. The fibers help to transfer load to the internal micro cracks. FRC is cement based composite material that has been developed in recent years. It has been successfully used in construction with its excellent flexural-tensile strength, resistance to spitting, impact resistance and excellent permeability and frost resistance. It is an effective way to increase toughness, shock resistance and resistance to plastic shrinkage cracking of the mortar. These fibers have many benefits. Steel fibers can improve the structural strength to reduce in the heavy steel reinforcement requirement. Freeze thaw resistance of the concrete is improved. Durability of the concrete is improved to reduce in the crack widths. Polypropylene and Nylon fibers are used to improve the impact resistance. Many developments have been made in the fiber reinforced concrete.

  12. Use of SCC in Prefabricated Concrete Elements

    DEFF Research Database (Denmark)

    Thrane, Lars Nyholm; Lauritsen, Ib

    2004-01-01

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

  13. Cement and Concrete Nanoscience and Nanotechnology

    Directory of Open Access Journals (Sweden)

    Taijiro Sato

    2010-02-01

    Full Text Available Concrete science is a multidisciplinary area of research where nanotechnology potentially offers the opportunity to enhance the understanding of concrete behavior, to engineer its properties and to lower production and ecological cost of construction materials. Recent work at the National Research Council Canada in the area of concrete materials research has shown the potential of improving concrete properties by modifying the structure of cement hydrates, addition of nanoparticles and nanotubes and controlling the delivery of admixtures. This article will focus on a review of these innovative achievements.

  14. Concrete under severe conditions. Environment and loading

    International Nuclear Information System (INIS)

    The objective of the CONSEC Conferences is to focus on concrete infrastructures, either subjected to severe environment or severe loading, or any combination of severe conditions. Experience from the performance of existing concrete structures, and especially under severe environmental conditions, severe accidental loading or extended lifespan, has demonstrated the need for better integration of structural and durability design, new design concepts including reliability-based durability design, performance-based material requirements, structural robustness, and an improved basis for documentation of obtained construction quality and durability properties during concrete construction. An improved basis for operation and preventive maintenance of concrete structures including repairs and retrofitting is also very important. Premature corrosion of reinforcing steel, inadequate structural design for seismic or blast loading, are examples of reduced service life of concrete structures that not only represent technical and economical problems, but also a huge waste of natural resources and hence also, an environmental and ecological problem. Experience of structures effectively submitted to severe conditions represents a unique benchmark for quantifying the actual safety and durability margin of concrete structures. In fact for several reasons, most concrete design codes, job specifications and other requirements for concrete structures have frequently shown to yield insufficient and unsatisfactory results and ability to solve the above problems, as well as issues raised by specific very long-term or very severe requirements for nuclear and industrial waste management, or civil works of strategic relevance. Recently available high to ultra-high performance concrete may find rational and valuable application in such cases. It is very important, therefore, to bring people with different professional backgrounds together to exchange experience and develop multi

  15. Radiation damage in reactor cavity concrete

    International Nuclear Information System (INIS)

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

  16. Properties of Fiber Reinforced Polymer Concrete

    Directory of Open Access Journals (Sweden)

    Marinela Bărbuţă

    2008-01-01

    Full Text Available Polymer concrete is a composite material realized with resin and aggregates. In the present study the epoxy resin was used for binding the aggregates. In the composition were introduced near the fly ash, used as filler, the cellulose fibers. The mechanical characteristics such as compressive strength, flexural strength and split tensile strength of polymer concrete with fibers were investigated. The fiber percentage was constant, the epoxy resin and the filler dosages were varied. The cellulose fiber had not improved the mechanical characteristics of the polymer concrete in comparison to that of polymer concrete without cellulose fibers.

  17. Equipment for removal of contaminated concrete surfaces

    International Nuclear Information System (INIS)

    The Pacific Northwest Laboratory is investigating and developing equipment that will rapidly and economically remove contaminated concrete surfaces while producing a minimal amount of contaminated rubble. Evaluation of various methods for removing concrete surfaces shows that many of the techniques presently used for decontamination require excessive manpower, time, or energy, or they remove more material than is necessary to clean the surface. Excess material removal increases the quantity of waste that must be handled under controlled conditions. Three unique decontamination methods are presented here: the water cannon, the concrete spaller, and the high-pressure water jet. The water cannon fires a small, high-velocity jet of fluid to spall the concrete surface. The concrete spaller ships away the concrete by exerting radial pressure against the sides of a shallow cylindrical hole drilled into the concrete surface. The high-pressure water jet is a 50,000-psi spray that blasts away the concrete surface. Each method includes means for containing airborne contamination. Results of tests show that these techniques can rapidly and economically remove surfaces, leaving minimal rubble for controlled disposal. Also presented are cost comparisons between the water cannon and the concrete spaller

  18. Proceedings of the concrete decontamination workshop

    International Nuclear Information System (INIS)

    Fourteen papers were presented. These papers describe concrete surface removal methods and equipment, as well as experiences in decontaminating and removing both power and experimental nuclear reactors

  19. Proceedings of the concrete decontamination workshop

    Energy Technology Data Exchange (ETDEWEB)

    Halter, J.M.; Sullivan, R.G.; Currier, A.J.

    1980-05-28

    Fourteen papers were presented. These papers describe concrete surface removal methods and equipment, as well as experiences in decontaminating and removing both power and experimental nuclear reactors.

  20. Experimental needs of high temperature concrete

    International Nuclear Information System (INIS)

    The needs of experimental data on concrete structures under high temperature, ranging up to about 3700C for operating reactor conditions and to about 9000C and beyond for hypothetical accident conditions, are described. This information is required to supplement analytical methods which are being implemented into the finite element code TEMP-STRESS to treat reinforced concrete structures. Recommended research ranges from material properties of reinforced/prestressed concrete, direct testing of analytical models used in the computer codes, to investigations of certain aspects of concrete behavior, the phenomenology of which is not well understood. 10 refs