WorldWideScience

Sample records for rapid concrete deterioration

  1. Concrete pavement joint deterioration.

    Science.gov (United States)

    2015-12-01

    Concrete pavements are an important part of our national infrastructure. In recent years the relatively small number of reported joints deteriorating prematurely in concrete pavements around Indiana has increased. Changes over the past 45 years in IN...

  2. 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...

  3. Analysis and assessment of microbial biofilm-mediated concrete deterioration.

    Science.gov (United States)

    2008-10-01

    Inspections of bridge substructures in Texas identified surface deterioration of reinforced concrete columns on : bridges continuously exposed water. Initial hypothesis were that the surface deterioration was a result of the : acidity of the water in...

  4. Characterization and mediation of microbial deterioration of concrete bridge structures.

    Science.gov (United States)

    2013-04-01

    Samples obtained from deteriorated bridge structures in Texas were cultured in growth medium containing thiosulfate as an energy source and investigated for acid production, type of acid produced by microbes and the bio-deterioration of concrete cyli...

  5. Modelling of the Deterioration of Reinforced Concrete Structures

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    Stochastic modelling of the deterioration of reinforced concrete structures is addressed in this paper on basis of a detailed modelling of corrosion initiation and corrosion cracking. It is proposed that modelling of the deterioration of concrete should be based on a sound understanding...... of the physical and chemical properties of the concrete. The relationship between rebar corrosion and crack width is investigated. A new service life definition based on evolution of the corrosion crack width is proposed....

  6. Deterioration of jointed Portland cement concrete pavements.

    Science.gov (United States)

    1975-01-01

    Information has been gathered regarding the performance of more than 400 lane-miles of jointed PCC interstate pavements located in five construction districts in Virginia. The factors causing pavement deterioration have been identified, the processes...

  7. Ultrasonic measurements of undamaged concrete layer thickness in a deteriorated concrete structure

    NARCIS (Netherlands)

    Demcenko, A.; Visser, Roy; Akkerman, Remko

    2016-01-01

    Ultrasonic wave propagation in deteriorated concrete structures was studied numerically and experimentally. Ultrasonic single-side access immersion pulse-echo and diffuse field measurements were performed in deteriorated concrete structures at 0.5 MHz center frequency. Numerically and experimentally

  8. Polarization Induced Deterioration of Reinforced Concrete with CFRP Anode.

    Science.gov (United States)

    Zhu, Ji-Hua; Wei, Liangliang; Zhu, Miaochang; Sun, Hongfang; Tang, Luping; Xing, Feng

    2015-07-15

    This paper investigates the deterioration of reinforced concrete with carbon fiber reinforced polymer (CFRP) anode after polarization. The steel in the concrete was first subjected to accelerated corrosion to various extents. Then, a polarization test was performed with the external attached CFRP as the anode and the steel reinforcement as the cathode. Carbon fiber reinforced mortar and conductive carbon paste as contact materials were used to adhere the CFRP anode to the concrete. Two current densities of 1244 and 2488 mA/m², corresponding to the steel reinforcements were applied for 25 days. Electrochemical parameters were monitored during the test period. The deterioration mechanism that occurred at the CFRP/contact material interface was investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The increase of feeding voltage and the failure of bonding was observed during polarization process, which might have resulted from the deterioration of the interface between the contact material and CFRP. The formation and accumulation of NaCl crystals at the contact material/CFRP interface were inferred to be the main causes of the failure at the interface.

  9. Design Of A Laboratory Set-up For Evaluating Structural Strength Of Deteriorated Concrete Sewer Pipes

    NARCIS (Netherlands)

    Stanic, N.; Salet, T.; Langeveld, J.G.; Clemens, F.H.L.R.

    2014-01-01

    The principle of structural behaviour of buried concrete pipes is fairly understood, except for how material deterioration affects structural behaviour and performance. Consequently, information on the structural behaviour of deteriorated sewer pipes will contribute to better understanding of the

  10. Concrete deterioration: detection by ultrasonic pulse velocity method

    International Nuclear Information System (INIS)

    Sutan, N.M.; Jaafar, M.S.; Hamdan, S.

    2003-01-01

    Tests were performed to evaluate the feasibility of using Ultrasonic Pulse Velocity Method (UPVM) in detecting defect and determining its depth during the early age concrete. Five reinforced concrete (RC) slabs of grade 30, 40 and 50 specimens at day 3, 7,14 and 28 with a fabricated void at a known location were used. The results obtained were compared to determine the accuracy of the method hence the effectiveness of the method with different strength and as the concrete matures. This method detects defects in specimens during the early age The accuracy varies with concrete strength and as the concrete mature. The test results indicate the method can be used to assess the in-situ properties of concrete or for quality control on site. The method showed better accuracy with stronger concrete detects defects with the accuracy ranging from 55.75-99.62% from day 3-28 (full strength) respectively. (author)

  11. Evaluation of Seismic Behaviors of Partially Deteriorated Reinforced Concrete Circular Columns Retrofitted with CFRP

    Directory of Open Access Journals (Sweden)

    Dongxu Hou

    2014-01-01

    Full Text Available Deficiency of the concrete strength in some regions of reinforced concrete (RC columns in practice may weaken the seismic behaviors of columns. Its effects on RC columns should be well understood. This paper aims to investigate the influences of deteriorated segment on the seismic behaviors of partially deteriorated RC columns and attempts to recover the seismic behaviors of partially deteriorated columns with Carbon Fiber Reinforced Polymer (CFRP composites. A finite element analysis was carried out to simulate the seismic behaviors of CFRP-confined partially deteriorated RC columns. The numerical results were verified by the laboratory tests of six specimens. Based on the finite element results, the failure location of partially deteriorated columns in an earthquake was predicted, and the effectiveness of CFRP retrofitted on partially deteriorated columns was evaluated.

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

    International Nuclear Information System (INIS)

    Gregerova, Miroslava; Vsiansky, Dalibor

    2009-01-01

    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.

  13. Risk-based replacement strategies for redundant deteriorating reinforced concrete pipe networks

    International Nuclear Information System (INIS)

    Adey, B.; Bernard, O.; Gerard, B.

    2003-01-01

    This paper gives an example of how predictive models of the deterioration of reinforced concrete pipes and the consequences of failure can be used to develop risk-based replacement strategies for redundant reinforced concrete pipe networks. It also shows how an accurate deterioration prediction can lead to a reduction of agency costs, and illustrates the limitation of the incremental intervention step algorithm. The main conclusion is that the use of predictive models, such as those developed by Oxand S.A., in the determination of replacement strategies for redundant reinforced concrete pipe networks can lead to a significant reduction in overall costs for the owner of the structure. (author)

  14. Evaluation of microcracking and chemical deterioration in concrete pavements.

    Science.gov (United States)

    1995-10-31

    The major objective of this research project was to investigate the : chemistry and morphology of portland cement concrete pavements in : Iowa. The integrity of the various pavements was evaluated qualitatively, : based on the presence or absence of ...

  15. Research on Deterioration Mechanism of Concrete Materials in an Actual Structure

    Directory of Open Access Journals (Sweden)

    Shiping Zhang

    2014-01-01

    Full Text Available The cause for deterioration of the concrete structure located in severe environment has been explored both in field and in laboratory. Serious cracking and spalling appeared upon surface of the concrete structure soon after the structure was put into service. Both alkali-aggregate reaction and freeze-thaw cycles may result in similar macro visible cracking and spalling. The possibility of alkali-aggregate reaction was excluded by both field survey and lab examination such as chemical analysis, petrographic analysis, and determination of alkali reactivity of aggregates. According to results of freeze-thaw cycles, impermeability testing, and microstructure analysis, it is deduced that the severe environmental conditions plus the relatively inferior frost resistance cause the deterioration of concrete. Usage of air entraining admixture can improve frost resistance and impermeability. Furthermore, new approaches to mitigate the deterioration of concrete used in severe environmental condition are discussed.

  16. Advanced modelling of concrete deterioration due to reinforcement corrosion

    International Nuclear Information System (INIS)

    Isgor, O.B.; Razaqpur, A.G.

    2006-01-01

    A comprehensive model is presented for predicting the rate of steel corrosion in concrete structures and the consequent formation and propagation of cracks around the steel reinforcement. The corrosion model considers both the initiation and the propagation stages of corrosion. Processes commencing in the initiation stage, such as the transport of chloride ions and oxygen within the concrete and variation in temperature and moisture, are assumed to continue in the propagation stage while active corrosion is occurring contemporaneously. This allows the model to include the effects of changes in exposure conditions on the corrosion rate and the effects of the corrosion reactions on the transport properties of concrete. The corrosion rates are calculated by applying the finite-element solution of the Laplace equation for electrochemical potential, with appropriate boundary conditions. Because these boundary conditions are nonlinear, a nonlinear solution algorithm is used. The results of the analysis are compared with available test data, and the comparison is found to be satisfactory. (author)

  17. Deteriorated Concrete from Liner of WIPP Waste Shaft

    Science.gov (United States)

    1992-06-01

    for US Department of Energy. Bensted, J. 1989. "Novel Cements - Sorel and Related Chemical Cements," il Cemento , Vol 86, No. 4, pp 217-228. Ben-Yair, M...Waste Isolation Pilot Plant. Massazza, F. 1985. "Concrete Resistance to Sea Water and Marine Environment," il Cemento , Vol 82, No. 1, pp 3-26. Mather

  18. Seismic evaluation and retrofit of deteriorated concrete bridge components.

    Science.gov (United States)

    2013-06-01

    Corrosion of steel bars in reinforced concrete structures is a major durability problem for bridges constructed in the New York State : (NYS). The heavy use of deicing salt compounds this problem. Corrosion of steel bars results in loss of steel cros...

  19. Simulation of concrete deterioration in Finnish rock cavern conditions for final disposal of nuclear waste

    International Nuclear Information System (INIS)

    Kari, O.P.; Puttonen, J.

    2014-01-01

    Highlights: • Concrete deterioration in Finnish rock cavern disposal conditions was simulated. • Simulation requires advanced models instead of traditional linear diffusion models. • Concrete analysed performed moderately during the period of 500 years. • Corrosion of steel reinforcement cannot be excluded during the period analysed. - Abstract: A simulation of concrete ageing in Finnish rock cavern disposal conditions showed that the concrete undergoes complex deterioration processes during the period required for lowering the level of radiation. In respect of the concrete ageing, the life time of the disposal facilities shall be divided into the periods before and after the closing of the caverns. Generally, the sulphate-resistant type of concrete analysed performed moderately during the analysed period of 500 years contrary to the corrosion of steel reinforcement, which cannot be excluded. Simulation of ageing clearly requires thermodynamical methods instead of linear diffusion models based on Fick’s law, which are traditionally used in construction industry. The study proves that the thermodynamical simulation method developed with adequate experimental data also makes it possible to observe latent factors of concrete deterioration

  20. Quantifying reinforced concrete bridge deck deterioration using ground penetrating radar

    Science.gov (United States)

    Martino, Nicole Marie

    Bridge decks are deteriorating at an alarming rate due to corrosion of the reinforcing steel, requiring billions of dollars to repair and replace them. Furthermore, the techniques used to assess the decks don't provide enough quantitative information. In recent years, ground penetrating radar (GPR) has been used to quantify deterioration by comparing the rebar reflection amplitudes to technologies serving as ground truth, because there is not an available amplitude threshold to distinguish healthy from corroded areas using only GPR. The goal of this research is to understand the relationship between GPR and deck deterioration, and develop a model to determine deterioration quantities with GPR alone. The beginning of this research determines that not only is the relationship between GPR and rebar corrosion stronger than the relationship between GPR and delaminations, but that the two are exceptionally correlated (90.2% and 86.6%). Next, multiple bridge decks were assessed with GPR and half-cell potential (HCP). Statistical parameters like the mean and skewness were computed for the GPR amplitudes of each deck, and coupled with actual corrosion quantities based on the HCP measurements to form a future bridge deck model that can be used to assess any deck with GPR alone. Finally, in order to understand exactly which component of rebar corrosion (rust, cracking or chloride) attenuates the GPR data, computational modeling was carried out to isolate each variable. The results indicate that chloride is the major contributor to the rebar reflection attenuation, and that computational modeling can be used to accurately simulate GPR attenuation due to chloride.

  1. Another look at the deterioration of calcium aluminate cement concrete

    Directory of Open Access Journals (Sweden)

    Jambor, Jaromir

    1996-03-01

    Full Text Available Potential degradation of concrete structures made of calcium aluminate cement (CAC is well known and is caused by transformation (conversion of the thermodynamically metastable into stable calcium aluminate hydrate phases. This recrystallization is influenced by temperature and humidity; the structural degradation of the concrete itself thus its loss of strength, is strongly related to the pore structure of the hydrated cement paste, the critical parameters being the total volume of pores below 15-20 nm and the median micropore radius. This constitutes a novel procedure for evaluation of existing CAC concrete structure.

    La degradación potencial de estructuras de hormigón elaboradas con cemento aluminoso (CA es bien conocida. Este deterioro está causado por la recristalización (conversión de las fases del aluminato cálcico que son termodinámicamente metastables, en fases estables. En esta recristalización influye la temperatura y la humedad. Tanto la degradación del propio hormigón, como su pérdida de resistencias están relacionadas estrechamente con la estructura porosa de la pasta del cemento hidratado, siendo parámetros críticos el volumen total de los poros inferiores a 15-20 nm y el tamaño medio de los radios de los microporos. Esto constituye un nuevo procedimiento para evaluar las estructuras existentes de hormigón de cemento aluminoso (CA.

  2. On Deterioration Mechanism of Concrete Exposed to Freeze-Thaw Cycles

    Science.gov (United States)

    Trofimov, B. Ya; Kramar, L. Ya; Schuldyakov, K. V.

    2017-11-01

    At present, concrete and reinforced concrete are gaining ground in all sectors of construction including construction in the extreme north, on shelves, etc. Under harsh service conditions, the durability of reinforced concrete structures is related to concrete frost resistance. Frost resistance tests are accompanied by the accumulation of residual dilation deformations affected by temperature-humidity stresses, ice formation and other factors. Porosity is an integral part of the concrete structure which is formed as a result of cement hydration. The prevailing hypothesis of a deterioration mechanism of concrete exposed to cyclic freezing, i.e. the hypothesis of hydraulic pressure of unfrozen water in microcapillaries, does not take into account a number of phenomena that affect concrete resistance to frost aggression. The main structural element of concrete, i.e. hardened cement paste, contains various hydration products, such as crystalline, semicrystalline and gel-like products, pores and non-hydrated residues of clinker nodules. These structural elements in service can gain thermodynamic stability which leads to the concrete structure coarsening, decrease in the relaxation capacity of concrete when exposed to cycling. Additional destructive factors are leaching of portlandite, the difference in thermal dilation coefficients of hydration products, non-hydrated relicts, aggregates and ice. The main way to increase concrete frost resistance is to reduce the macrocapillary porosity of hardened cement paste and to form stable gel-like hydration products.

  3. Study on concrete cask for practical use. Development of evaluation method of salt-induced deterioration of reinforced concrete

    International Nuclear Information System (INIS)

    Matsumura, Takuro; Shirai, Koji; Saegusa, Toshiari

    2005-01-01

    We studied an evaluation method of salt-induced deterioration of reinforced concrete structures under high temperatures. For this purpose, we conducted chloride ion diffusion tests of concrete specimens, corrosion tests of reinforced concrete specimens and combined tests of carbonation and chloride ion penetration of concrete specimens under high temperatures. We discussed the effects of temperature on chloride ion diffusion coefficient in concrete, temperature on chloride ion concentration for initiation of reinforcing steel corrosion and carbonation on chloride ion diffusion coefficient at high temperatures. The findings obtained through this study can be summarized as follows: (a) The value of diffusion coefficient of chloride ion in concrete became larger with the increase of temperature. A roughly linear relationship between logarithm of the diffusion coefficient and reciprocal of absolute temperature was confirmed. (b) Threshold chloride ion concentration for initiation of steel corrosion stays almost unchanged even in high temperatures. (c) The value of diffusion coefficient of chloride ion is presumably larger in carbonated concrete. (d) A method to evaluate chloride effect on reinforced concrete structures was developed by incorporating the above test results into current design practice under normal temperatures. (author)

  4. Estimation of Concrete Carbonation Depth Considering Multiple Influencing Factors on the Deterioration of Durability for Reinforced Concrete Structures

    Directory of Open Access Journals (Sweden)

    Hae-Chang Cho

    2016-01-01

    Full Text Available While the durability of concrete structures is greatly influenced by many factors, previous studies typically considered only a single durability deterioration factor. In addition, these studies mostly conducted their experiments inside the laboratory, and it is extremely hard to find any case in which data were obtained from field inspection. Accordingly, this study proposed an Adaptive Neurofuzzy Inference System (ANFIS algorithm that can estimate the carbonation depth of a reinforced concrete member, in which combined deterioration has been reflected based on the data obtained from field inspections of 9 buildings. The proposed ANFIS algorithm closely estimated the carbonation depths, and it is considered that, with further inspection data, a higher accuracy would be achieved. Thus, it is expected to be used very effectively for durability estimation of a building of which the inspection is performed periodically.

  5. Experimental study and field application of calcium sulfoaluminate cement for rapid repair of concrete pavements

    Institute of Scientific and Technical Information of China (English)

    Yanhua GUAN; Ying GAO; Renjuan SUN; Moon C.WON; Zhi GE

    2017-01-01

    The fast-track repair of deteriorated concrete pavement requires materials that can be placed,cured,and opened to the traffic in a short period.Type Ⅲ cement and Calcium Sulfoaluminate (CSA) cement are the most commonly used fast-setting hydraulic cement (FSHC).In this study,the properties of Type Ⅲ and CSA cement concrete,including compressive strength,coefficient of thermal expansion (CTE) and shrinkage were evaluated.The test results indicate that compressive strength of FSHC concrete increased rapidly at the early age.CSA cement concrete had higher early-age and long term strength.The shrinkage of CSA cement concrete was lower than that of Type Ⅲ cement concrete.Both CSA and Type Ⅲ cement concrete had similar CTE values.Based on the laboratory results,the CSA cement was selected as the partial-depth rapid repair material for a distressed continuously reinforced concrete pavement.The data collected during and after the repair show that the CSA cement concrete had good short-term and long-term performances and,therefore,was suitable for the rapid repair of concrete pavement.

  6. Rapid construction of concrete pressure vessels

    International Nuclear Information System (INIS)

    Limbert, D.; Weatherseed, D.C.

    1989-01-01

    This paper opens with a general description of the concrete pressure vessel followed by a more detailed examination of the critical elements of the construction, including choice of methods and plant which were selected to ensure its rapid construction. The pressure vessel construction cannot be treated in isolation, because it is very closely linked with its surrounding structures - namely the reactor hall which surrounds it and the charge hall which tops it, as will be seen in the context of this paper. Rate of progress of construction is not entirely in the civil contractor's hands because so many of the operations affecting the civil works are of a mechanical nature, hence a very close liaison and understanding amongst all contractors concerned was of the utmost importance. (author)

  7. An Investigation of Concrete Deterioration at South Florida Water Management District Structure S65E

    Science.gov (United States)

    2014-02-01

    deterioration by dissolution of certain concrete com- ponents, specifically limestone ( calcium carbonate, CaCO3) aggregate and portlandite in the paste...K) 2.98 Sodium (Na) 14.6 Calcium (Ca) 19.1 Copper (Cu) 0.0011 Manganese (Mn) 0.0057 Nickel (Ni) 0.0012 Vanadium (V) 0.0011 Zinc (Zn) 0.0189...5A. Water quality differences are consistent with the surface geology at the respective sites. The Kissimmee River Basin is characterized by

  8. Role of alkalis of aggregate origin in the deterioration of CAC concrete

    International Nuclear Information System (INIS)

    Blanco-Varela, M.T.; Martinez-Ramirez, S.; Vazquez, T.; Sanchez-Moral, S.

    2005-01-01

    Both hexagonal and cubic calcium aluminate cement (CAC) hydrates react with atmospheric CO 2 , bringing about mineralogical changes in concrete, which may, on occasion, lead to loss of mechanical strength. Alkaline hydrolysis or carbonation in the presence of alkalis is a highly destructive process. The purpose of the study was to determine what caused CAC concrete deterioration in a prestressed beam that had suffered intense external damage and showed signs of alkaline hydrolysis or a reaction between the aggregate and the cement. Samples of the internal (sound) and external (damaged) parts of the concrete were studied using XRF, XRD, FTIR, OM, SEM/EDX, and BSE techniques, and mechanical strength was measured on microspecimens extracted from both zones. The conclusion drawn from these analyses was that alkaline hydrolysis took place on or near the surface of the concrete. The white deposits observed around the alkali-containing aggregate were found to consist primarily of bayerite whose very loose consistency undermined the aggregate-matrix bond, greatly weakening the material

  9. A real case of steam-cured concrete track slab premature deterioration due to ASR and DEF

    Directory of Open Access Journals (Sweden)

    Kunlin Ma

    2017-06-01

    Full Text Available Deterioration mechanisms of some premature damaged steam-cured concrete track slabs (CTS in Chinese railway less than 4 years were investigated. Field investigation, raw materials test and suspicious products analysis were carried out. Results show that steam-cured heat damage (SCHD of concrete takes place in steam-cured process. Expansion products are ettringite in hydrated products and alkali-silica gels between the interface of hydrated products and coarse aggregate. SCHD makes CTS surface layer loose, porous and more micro-cracks. Long-term fatigue load from high-speed train acting on CTS enlarges concrete microcracks, leading to water penetrating into concrete easily in moist and rainy environment. In the process of water ingression, alkali-silica reaction (ASR and delayed ettringite formation (DEF take place, hence resulting in CTS cracking and premature deterioration.

  10. The establishment of a method for evaluating the long-term water-tightness durability of underground concrete structure taking into account some deteriorations

    International Nuclear Information System (INIS)

    Hironaga, Michihiko; Kawanishi, Motoi

    1996-01-01

    To establish a method of evaluating the long-term water-tightness durability of underground concrete structures, the authors firstly studied a deterioration evaluation model to express the deterioration condition of concrete structures and constructed, on the basis of this model, a function evaluation model to estimate the lowering of functions due to deterioration, consequently indicating a 'concept for evaluating the deterioration and functions of concrete structures' which will make it possible to perform the functional evaluation of concrete structures. Based on this concept, the authors then discusses a technique for evaluating the long-term water-tightness durability of underground concrete structures, specifically indicating the technique by means of illustrations. (author)

  11. Enamel coated steel reinforcement for improved durability and life-cycle performance of concrete structures: microstructure, corrosion, and deterioration

    Science.gov (United States)

    Tang, Fujian

    This study is aimed (a) to statistically characterize the corrosion-induced deterioration process of reinforced concrete structures (concrete cracking, steel mass loss, and rebar-concrete bond degradation), and (b) to develop and apply three types of enamel-coated steel bars for improved corrosion resistance of the structures. Commercially available pure enamel, mixed enamel with 50% calcium silicate, and double enamel with an inner layer of pure enamel and an outer layer of mixed enamel were considered as various steel coatings. Electrochemical tests were respectively conducted on steel plates, smooth bars embedded in concrete, and deformed bars with/without concrete cover in 3.5 wt.% NaCl or saturated Ca(OH)2 solution. The effects of enamel microstructure, coating thickness variation, potential damage, mortar protection, and corrosion environment on corrosion resistance of the steel members were investigated. Extensive test results indicated that corrosion-induced concrete cracking can be divided into four stages that gradually become less correlated with corrosion process over time. The coefficient of variation of crack width increases with the increasing level of corrosion. Corrosion changed the cross section area instead of mechanical properties of steel bars. The bond-slip behavior between the corroded bars and concrete depends on the corrosion level and distribution of corrosion pits. Although it can improve the chemical bond with concrete and steel, the mixed enamel coating is the least corrosion resistant. The double enamel coating provides the most consistent corrosion performance and is thus recommended to coat reinforcing steel bars for concrete structures applied in corrosive environments. Corrosion pits in enamel-coated bars are limited around damage locations.

  12. Use of Just in Time Maintenance of Reinforced Concrete Bridge Structures based on Real Historical Data Deterioration Models

    Directory of Open Access Journals (Sweden)

    Abu-Tair A.

    2016-01-01

    Full Text Available Concrete is the backbone of any developed economy. Concrete can suffer from a large number of deleterious effects including physical, chemical and biological causes. Large owning bridge structures organizations are facing very serious questions when asking for maintenance budgets. The questions range from needing to justify the need for the work, its urgency, to also have to predict or show the consequences of delayed rehabilitation of a particular structure. There is therefore a need for a probabilistic model that can estimate the range of service lives of bridge populations and also the likelihood of level of deteriorations it can reached for every incremental time interval. A model was developed for such estimation based on statistical data from actual inspection records of a large reinforced concrete bridge portfolio. The method used both deterministic and stochastic methods to predict the service life of a bridge, using these service lives in combination with the just in time (JIT principle of management would enable maintenance managers to justify the need for action and the budgets needed, to intervene at the optimum time in the life of the structure and that of the deterioration. The paper will report on the model which is based on a large database of deterioration records of concrete bridges covering a period of over 60 years and include data from over 400 bridge structures. The paper will also illustrate how the service life model was developed and how these service lives combined with the JIT can be used to effectively allocate resources and use them to keep a major infrastructure asset moving with little disruption to the transport system and its users.

  13. Multi-physical and multi-scale deterioration modelling of reinforced concrete part II: Coupling corrosion and damage at the structural scale

    DEFF Research Database (Denmark)

    Lepech, Michael; Rao, Anirudh; Kiremidjian, Anne

    2015-01-01

    Deterioration of reinforced concrete infrastructure such as bridges, tunnels, and buildings represents one of the major challenges currently facing developed countries. This deterioration leads to economic costs for maintenance and replacement, environmental impacts such increased global warming...... potential as a result of cement production and traffic emissions, and social costs related to traffic congestion and human health concerns. While engineering tools and methods for structural modelling and design of new reinforced concrete infrastructure are mature, the methods and tools for modelling...

  14. High Early-Age Strength Concrete for Rapid Repair

    Science.gov (United States)

    Maler, Matthew O.

    The aim of this research was to identify High Early-Age Strength (HES) concrete batch designs, and evaluate their suitability for use in the rapid repair of highways and bridge decks. To this end, two criteria needed to be met; a minimum compressive strength of 20.68 MPa (3000 psi) in no later than 12 hours, and a drying shrinkage of less than 0.06 % at 28 days after curing. The evaluations included both air-entrained, and non-air-entrained concretes. The cement types chosen for this study included Type III and Type V Portland cement and "Rapid Set"--a Calcium Sulfoaluminate (CSA) cement. In addition, two blended concretes containing different ratios of Type V Portland cement and CSA cement were investigated. The evaluation of the studied concretes included mechanical properties and transport properties. Additionally, dimensional stability and durability were investigated. Evaluations were conducted based on cement type and common cement factor. Fresh property tests showed that in order to provide a comparable workability, and still remain within manufactures guideline for plasticizer, the water-to-cement ratio was adjusted for each type of cement utilized. This resulted in the need to increase the water-to-cement ratio as the Blaine Fineness of the cement type increased (0.275 for Type V Portland cement, 0.35 for Type III Portland cement, and 0.4 for Rapid Set cement). It was also observed that negligible changes in setting time occurred with increasing cement content, whereas changes in cement type produced notable differences. The addition of air-entrainment had beneficial effect on workability for the lower cement factors. Increasing trends for peak hydration heat were seen with increases in cement factor, cement Blaine Fineness, and accelerator dosage. Evaluation of hardened properties revealed opening times as low as 5 hours for Type V Portland cement with 2.0 % accelerator per cement weight and further reduction in opening time by an hour when accelerator

  15. Multi-physical and multi-scale deterioration modelling of re-inforced concrete: modelling corrosion-induced concrete damage

    DEFF Research Database (Denmark)

    Michel, Alexander; Lepech, Michael; Stang, Henrik

    2016-01-01

    for the discretization of the concrete domain. To model the expansive nature of solid corrosion products, a thermal analogy is used. The modelling approach further accounts for the penetration of solid corrosion products into the available pore space of the surrounding cementitious materials and non-uniform distribution...

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  17. Integrated modelling of corrosion-induced deterioration in rein-forced concrete structures

    DEFF Research Database (Denmark)

    Michel, Alexander; Geiker, M.R.; Stang, Henrik

    2013-01-01

    at the reinforcement surface, a FEM based me-chanical model was used to simulate corrosion-induced concrete damage. Both FEM models were fully coupled, i.e. information, such as corrosion current density, dam-age state of concrete cover, etc., were constantly exchanged between the models. To demonstrate the potential......An integrated finite element based modelling approach is presented, which allows for fully coupled simulation of reinforcement corrosion and corrosion-induced concrete damage. While a finite element method (FEM) based corrosion model was used to describe electrochemical processes...... use of the modelling approach, a numerical example is presented which illustrates full coupling of formation of corrosion cells, propagation of corrosion, and subsequent development of corrosion-induced concrete damage....

  18. Leaching of concrete : the leaching process : extrapolation of deterioration : effect on the structural stability

    OpenAIRE

    Fagerlund, Göran

    2000-01-01

    The leaching process when water attacks concrete, and the effect of leaching on the strength and durability of a concrete structure, is analysed theoretically. Technique for prediction of the future leaching and structural stability is outlined. The analysis is to a certain extent supported by data from literature. The leaching process is divided in five different types: 1: Pure surface leaching 2: Surface leaching involving erosion 3: Homogeneous leaching over the entire structure 4...

  19. Assessing and updating the reliability of concrete bridges subjected to spatial deterioration - principles and software implementation

    DEFF Research Database (Denmark)

    Schneider, Ronald; Fischer, Johannes; Bügler, Maximilian

    2015-01-01

    to implement the method presented here. The software prototype is applied to a typical highway bridge and the influence of inspection information on the system deterioration state and the structural reliability is quantified taking into account the spatial correlation of the corrosion process. This work...

  20. Rapid Deterioration of Basic Life Support Skills in Dentists With Basic Life Support Healthcare Provider.

    Science.gov (United States)

    Nogami, Kentaro; Taniguchi, Shogo; Ichiyama, Tomoko

    2016-01-01

    The aim of this study was to investigate the correlation between basic life support skills in dentists who had completed the American Heart Association's Basic Life Support (BLS) Healthcare Provider qualification and time since course completion. Thirty-six dentists who had completed the 2005 BLS Healthcare Provider course participated in the study. We asked participants to perform 2 cycles of cardiopulmonary resuscitation on a mannequin and evaluated basic life support skills. Dentists who had previously completed the BLS Healthcare Provider course displayed both prolonged reaction times, and the quality of their basic life support skills deteriorated rapidly. There were no correlations between basic life support skills and time since course completion. Our results suggest that basic life support skills deteriorate rapidly for dentists who have completed the BLS Healthcare Provider. Newer guidelines stressing chest compressions over ventilation may help improve performance over time, allowing better cardiopulmonary resuscitation in dental office emergencies. Moreover, it may be effective to provide a more specialized version of the life support course to train the dentists, stressing issues that may be more likely to occur in the dental office.

  1. In Situ Repair of Deteriorated Concrete in Hydraulic Structures: Feasibility Study

    Science.gov (United States)

    1987-05-01

    concrete along the length of the crack; installing grout nipples at intervals, and sealing the crack between the nipples ; flushing the crack to clean...totally dependent upon the size and magnitude of the work to be done. Small jobs can probably be handled by a work crew of four or five men , whereas

  2. Early warning systems and rapid response to the deteriorating patient in hospital: A realist evaluation.

    Science.gov (United States)

    McGaughey, Jennifer; O'Halloran, Peter; Porter, Sam; Trinder, John; Blackwood, Bronagh

    2017-12-01

    To test the Rapid Response Systems programme theory against actual practice components of the Rapid Response Systems implemented to identify those contexts and mechanisms which have an impact on the successful achievement of desired outcomes in practice. Rapid Response Systems allow deteriorating patients to be recognized using Early Warning Systems, referred early via escalation protocols and managed at the bedside by competent staff. Realist evaluation. The research design was an embedded multiple case study approach of four wards in two hospitals in Northern Ireland which followed the principles of Realist Evaluation. We used various mixed methods including individual and focus group interviews, observation of nursing practice between June-November 2010 and document analysis of Early Warning Systems audit data between May-October 2010 and hospital acute care training records over 4.5 years from 2003-2008. Data were analysed using NiVivo8 and SPPS. A cross-case analysis highlighted similar patterns of factors which enabled or constrained successful recognition, referral and response to deteriorating patients in practice. Key enabling factors were the use of clinical judgement by experienced nurses and the empowerment of nurses as a result of organizational change associated with implementation of Early Warning System protocols. Key constraining factors were low staffing and inappropriate skill mix levels, rigid implementation of protocols and culturally embedded suboptimal communication processes. Successful implementation of Rapid Response Systems was dependent on adopting organizational and cultural changes that facilitated staff empowerment, flexible implementation of protocols and ongoing experiential learning. © 2017 John Wiley & Sons Ltd.

  3. Structural condition assessment and service load performance of deteriorated prestressed concrete deck beam bridges

    Science.gov (United States)

    Fuentes, Juan Bolivar

    Precast pretensioned deck beam bridges are a generic bridge type widely used by IDOT for new construction through the end of the 1970's and still widely used on county roads throughout Illinois. While these bridges were economical to build, IDOT discontinued their use because reflective cracks developed along the length of the longitudinal joints between beams. Three 30 years old deteriorated beams were removed from an existing bridge over Spoon River in Fulton County, IL and delivered to Newmark Civil Engineering Laboratory. The program consisted of a series of comprehensive, destructive and non-destructive, tests and evaluations of the three beams with emphasis on three major areas; (1) The Condition Assessment of the as-delivered beams. (2) The service load performance of the bridge sub-assemblage constructed from those beams. After a comprehensive inspection of the beams was completed, the beams were integrated together into a bridge subassembly that simulated a bridge lane. (3) Following the service load tests, the three beams were separated and tested individually to failure. The critical signs to be observed in existing structures that will lead the inspectors to conclude that a deck beam is being overloaded were are also studied. Several conclusions were found. Cracking of the longitudinal joint has little effect on the stiffness of the bridge if the transverse rod is snug. The presence of a snug transverse tie rod increases the strength of the longitudinal joint. After a longitudinal joint has fractured, reincorporating a snug transverse rod can significantly reestablish the stiffness of the longitudinal joint and reduce overloading of a deteriorated beam. Participation factors must be based on relative bending moments of one beam with respect to the total amount of bending moment produced by the applied load and not to the amount of total vertical displacement. The participation factors will vary along the span of the bridge deck and will depend on the

  4. Consumer participation in early detection of the deteriorating patient and call activation to rapid response systems: a literature review.

    Science.gov (United States)

    Vorwerk, Jane; King, Lindy

    2016-01-01

    This review investigated the impact of consumer participation in recognition of patient deterioration and response through call activation in rapid response systems. Nurses and doctors have taken the main role in recognition and response to patient deterioration through hospital rapid response systems. Yet patients and visitors (consumers) have appeared well placed to notice early signs of deterioration. In response, many hospitals have sought to partner health professionals with consumers in detection and response to early deterioration. However, to date, there have been no published research-based reviews to establish the impact of introducing consumer involvement into rapid response systems. A critical research-based review was undertaken. A comprehensive search of databases from 2006-2014 identified 11 studies. Critical appraisal of these studies was undertaken and thematic analysis of the findings revealed four major themes. Following implementation of the consumer activation programmes, the number of calls made by the consumers following detection of deterioration increased. Interestingly, the number of staff calls also increased. Importantly, mortality numbers were found to decrease in one major study following the introduction of consumer call activation. Consumer and staff knowledge and satisfaction with the new programmes indicated mixed results. Initial concerns of the staff over consumer involvement overwhelming the rapid response systems did not eventuate. Evaluation of successful consumer-activated programmes indicated the importance of: effective staff education and training; ongoing consumer education by nurses and clear educational materials. Findings indicated positive patient outcomes following introduction of consumer call activation programmes within rapid response systems. Effective consumer programmes included information that was readily accessible, easy-to-understand and available in a range of multimedia materials accompanied by the

  5. Performance of Engineered Cementitious Composites for Concrete Repairs

    NARCIS (Netherlands)

    Zhou, J.

    2011-01-01

    Background and goals of this thesis The concrete repair, rehabilitation and retrofitting industry grows rapidly, driven by deterioration of, damage to and defects in concrete structures. However, it is well known that to achieve durable concrete repairs is very difficult. The failure of concrete

  6. Development and validation of deterioration models for concrete bridge decks - phase 1 : artificial intelligence models and bridge management system.

    Science.gov (United States)

    2013-06-01

    This research documents the development and evaluation of artificial neural network (ANN) models to predict the condition ratings of concrete highway bridge decks in Michigan. Historical condition assessments chronicled in the national bridge invento...

  7. Oxyradical accumulation and rapid deterioration of soybean seeds due to field weathering.

    Science.gov (United States)

    Yadav, Sanjeev; Bhatia, V S; Guruprasad, K N

    2006-02-01

    The effect of field weathering on oxyradical accumulation and subsequent changes were studied in the seeds of soybean [Glycine max (L.) Merr.] cv. JS 71-05. Electron spin resonance (ESR) quantification of oxyradical revealed that field weathering plays an important role in acceleration of their accumulation. One week of weathering increased the accumulation of oxyradicals to almost 2-fold and triggered the deteriorative cascade, by enhancing the lipid peroxidation and membrane perturbation, leading to cell death in seed tissues and poor germinability and vigour of soybean seeds. Thus, the weather conditions at the time of physiological maturity to harvesting of crop are very crucial and the field weathering plays a critical role for the maintenance of seed quality.

  8. Rapid deterioration of sediment surface habitats in Bellingham Bay, Washington State, as indicated by benthic foraminifera.

    Science.gov (United States)

    Nesbitt, Elizabeth A; Martin, Ruth A; Martin, David E; Apple, Jude

    2015-08-15

    Foraminiferal assemblages in sediment grab samples were utilized to evaluate the impacts of anthropogenic activities on benthic habitats in Bellingham Bay, Washington State, U.S.A. Seventy-three samples taken in 1987, 1997, 2006 and 2010 yielded 35 species of foraminifera from 28 genera. Assemblage composition and diversity data indicate a marked deterioration between 1987 and 2010, contrary to the published Chemical Index, but analogous to the situation with macrobiota. Correlation of diversity with chemical pollutants and metals did not identify any significant correlations, however, an unrelated but highly relevant study of bottom water dissolved oxygen concentrations and pH in Bellingham Bay suggests eutrophication with accompanying hypoxia and acidification may be part of the cause. Thus, the metrics of contamination alone do not adequately characterize habitat viability, and benthic foraminiferal assemblages provide insight into the health of coastal ecosystems. Published by Elsevier Ltd.

  9. Rapid deterioration of pain sensory-discriminative information in short-term memory.

    Science.gov (United States)

    Rainville, Pierre; Doucet, Jean-Charles; Fortin, Marie-Chantale; Duncan, Gary H

    2004-08-01

    The assessment of pain and analgesic efficacy sometimes relies on the retrospective evaluation of pain felt in the immediate, recent or distant past, yet we have a very limited understanding of the processes involved in the encoding, maintenance and intentional retrieval of pain. We examine the properties of the short-term memory of thermal and pain sensation intensity with a delayed-discrimination task using pairs of heat pain, warm and cool stimulation in healthy volunteers. Performance decreased as a function of the inter-stimulus interval (ISI), indicating a robust deterioration of sensory information over the test period of 4-14 s. As expected, performance also decreased with smaller temperature differences (Delta-T) and shorter stimulus durations (6-2 s). The relation between performance and Delta-T was adequately described by a power function, the exponent of which increased linearly with longer ISI. Importantly, performance declined steadily with increasing ISI (from 6 to 14 s)--but only for pairs of heat pain stimuli that were relatively difficult to discriminate (Delta-T short-term memory for pain and temperature sensation intensity relies on a transient analog representation that is quickly degraded and transformed into a more resistant but less precise categorical format. This implies that retrospective pain ratings obtained even after very short delays may be rather inaccurate but relatively reliable.

  10. Rapid deterioration of Mooren?s ulcers after conjunctival flap: a review of 2 cases

    OpenAIRE

    Li, Saiqun; Deng, Yuqing; Du, Caiyuan; Huang, Haixiang; Zhong, Jing; Chen, Ling; Wang, Bowen; Yuan, Jin

    2017-01-01

    Background Conjunctival flaps are a widely used treatment for numerous corneal ulcers that are caused by microorganismal infections. However, whether it can be performed on immune-mediated corneal ulcers is controversial. Case presentation We present two cases of Mooren?s ulcer that were treated using conjunctival flap in an attempt to prevent further corneal perforation at their local hospital. A rapid acceleration in ulcer progression was observed after a conjunctival flap was applied. Ulti...

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

    Science.gov (United States)

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

    2009-01-01

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

  12. Rapid deterioration of Mooren's ulcers after conjunctival flap: a review of 2 cases.

    Science.gov (United States)

    Li, Saiqun; Deng, Yuqing; Du, Caiyuan; Huang, Haixiang; Zhong, Jing; Chen, Ling; Wang, Bowen; Yuan, Jin

    2017-06-15

    Conjunctival flaps are a widely used treatment for numerous corneal ulcers that are caused by microorganismal infections. However, whether it can be performed on immune-mediated corneal ulcers is controversial. We present two cases of Mooren's ulcer that were treated using conjunctival flap in an attempt to prevent further corneal perforation at their local hospital. A rapid acceleration in ulcer progression was observed after a conjunctival flap was applied. Ultimately, the two patients underwent corneal transplantation, which required the postoperative use of topical immunosuppressants and resulted in a final cure. In the current report, we also discussed this incorrect surgical choice via a review of conventional interventions that are used to treat Mooren's ulcer. These two cases demonstrate that keratoplasty combined with topical immunosuppressants is effective in treating Mooren's ulcer. Application of conjunctival flaps or autografting could promote progression of ulceration in Mooren's ulcers.

  13. Churg-Strauss syndrome associated with rapid deterioration of left ventricular diastolic dysfunction and conduction disturbance.

    Science.gov (United States)

    Chin, Jung Yeon; Yi, Jeong Eun; Youn, Ho-Joong

    2013-10-01

    Cardiac involvement in Churg-Strauss syndrome (CSS) is a major cause of mortality. Here we report a case of a 75-year-old woman with eosinophilic endomyocarditis due to CSS. An electrocardiogram showed intraventricular conduction delay, and echocardiography showed an impaired relaxation pattern and biventricular apical thickening. Magnetic resonance imaging revealed subendocardial delayed enhancement with biventricular apical thrombi. Endomyocardial biopsy showed perivascular eosinophilic infiltration. Despite resolution of the hypereosinophilia after steroid therapy, her left ventricular (LV) diastolic function worsened into a restrictive pattern and she died with a ventricular escape rhythm on her 14th day in the hospital. This case is unusual in that there was rapid progression of the LV diastolic dysfunction and conduction disturbance due to CSS. © 2013, Wiley Periodicals, Inc.

  14. Engineering aspects and time effects of rapid deterioration of sandstone in the tropical environment of Sabah, Malaysia

    NARCIS (Netherlands)

    Tating, F.F.; Hack, H.R.G.K.; Jetten, V.G.

    2013-01-01

    Cut slopes in rock masses start to deteriorate directly after excavation due to stress relief and weathering. The deterioration is a time dependent process that depends on the local climate and the rock mass including its history, and the environment. The amount of deterioration per time unit (‘the

  15. Long-term behaviors of phosphate-based rapid repairing material for concrete shafts in coal mines.

    Science.gov (United States)

    Lei, Feng; Zhen-Ya, Zhang; Xiao-Dong, Wen; Chao, Xin; Dong-Yuan, Hu

    2018-04-01

    Concrete structures in shaft linings are apt to deteriorate prematurely and therefore prompt restoration is required. In considering this, desulphurization fly ash and machine-made tuff sand are employed to fabricate a phosphate-based rapid repairing material. The long-term efficiency of the material is evaluated based on combined factors, so drying shrinkage, interfacial bonding strength, corrosion resistance, and combustibility of the specimens are tested and researched in this paper. Experimental results showed that, under a dry circumstance, the material goes through a minor expansion at an early stage. It goes into a stage of rapid contraction after one day and a stable contraction after seven days. After 28 days, the total deformation is 67 micro-strains. On the other hand, the fabricated material manifests an excellent mechanical property. The one hour bending strength and compressive strength were 9.2 MPa and 32.6 MPa, respectively. A long-term mine water flushing simulation demonstrates that only 10% bending strength is lost and the corrosion resistance coefficient stays above 0.8, so a very good corrosion resistance is thus achieved. What is more, this repairing material retains its stability even at a high temperature of 1000°C, revealing its good thermo-stability. All these prominent properties make it a good prospective material for real restoration applications.

  16. Feasibility of using the dispersive characteristic of surface wave to assess the depth of surface deterioration of reinforced concrete nuclear containment

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Chia-Chi; Huang, Chi-Luen; Chiang, Chih-Hong; Hsu, Keng-Tsang; Ke, Ying Tsu [Chaoyang Univ. of Technology, Taichung, Taiwan (China). Dept. of Construction Engineering

    2015-07-01

    Surface waves generated by an impact are used to assess depth of deterioration for thick concrete plate. The proposed method uses one receiver positioned away from the impacting source. The spectrogram of the group velocity obtained from the signal recorded from the receiver is calculated by Short-Time Fourier Transform and the reassigned technique. The impact duration and the source-receiver distance for concrete plate with different thickness of weak top layer are explored by finite-element modeling. The image in spectrogram fit better with the theoretical dispersion curve of Lamb-wave or SH-wave modes for composite plate when the source-receiver distance is longer. The definition of the image in the reassigned spectrogram is affected more by the impact-duration for solid case than for the cases with weak top layer. The preliminary results show the material property as well as the depth of the weak top layer can be evaluated by the proposed method.

  17. Concrete

    DEFF Research Database (Denmark)

    2015-01-01

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

  18. Investigation of Deterioration Behavior of Hysteretic Loops in Nonlinear Static Procedure Analysis of Concrete Structures with Shear Walls

    International Nuclear Information System (INIS)

    Ghodrati Amiri, G.; Amidi, S.; Khorasani, M.

    2008-01-01

    In the recent years, scientists developed the seismic rehabilitation of structures and their view points were changed from sufficient strength to the performance of structures (Performance Base Design) to prepare a safe design. Nonlinear Static Procedure analysis (NSP) or pushover analysis is a new method that is chosen for its speed and simplicity in calculations. 'Seismic Rehabilitation Code for Existing Buildings' and FEMA 356 considered this method. Result of this analysis is a target displacement that is the base of the performance and rehabilitation procedure of the structures. Exact recognition of that displacement could develop the workability of pushover analysis. In these days, Nonlinear Dynamic Analysis (NDP) is only method can exactly apply the seismic ground motions. In this case because it consumes time, costs very high and is more difficult than other methods, is not applicable as much as NSP. A coefficient used in NSP for determining the target displacement is C2 (Stiffness and Strength Degradations Coefficient) and is applicable for correcting the errors due to eliminating the stiffness and strength degradations in hysteretic loops. In this study it has been tried to analysis three concrete frames with shear walls by several accelerations that scaled according to FEMA 273 and FEMA 356. These structures were designed with Iranian 2800 standard (vers.3). Finally after the analyzing by pushover method and comparison results with dynamic analysis, calculated C2 was comprised with values in rehabilitation codes

  19. Condition assessment and methods of abatement of prestressed concrete box-beam deterioration, phase II : volume 1.

    Science.gov (United States)

    2009-04-13

    Side-by-side box-beam bridge constitutes approximately 17 percent of bridges built or replaced annually on : public roads and there is a renewed thrust to use this bridge type for rapid construction under the Highway for : LIFE program. Further, fail...

  20. Condition assessment and methods of abatement of prestressed concrete box-beam deterioration, phase II : volume 2.

    Science.gov (United States)

    2009-04-13

    Side-by-side box-beam bridge constitutes approximately 17 percent of bridges built or replaced annually on public roads and there is a renewed thrust to use this bridge type for rapid construction under the Highway for LIFE program. Further, failure ...

  1. Concrete

    OpenAIRE

    Kruse Aagaard, Anders

    2015-01-01

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

  2. FINITE ELEMENT ANALYSIS OF THE BEHAVIOUR OF REINFORCED CONCRETE COLUMNS CONFINED BY OVERLAPPING HOOPS SUBJECTED TO RAPID CONCENTRIC LOADING

    Directory of Open Access Journals (Sweden)

    Xiang Zeng

    2017-12-01

    Full Text Available The strain rate sensitivity of concrete material was discovered approximately one hundred years ago, and it has a marked effect on the behaviour of concrete members subjected to dynamic loadings such as strong earthquake and impact loading. Because of the great importance of the confined reinforced concrete (RC columns in RC structures, the dynamic behaviour of the columns induced by the strain rate effect has been studied, but only few experiments and analyses have been conducted. To investigate the behaviour of overlapping hoop-confined square reinforced normal-strength concrete columns, considering the strain rate effect at a strain rate of 10-5/sec to 10-1/sec induced by earthquake excitation, an explicit dynamic finite element analysis (FEA model was developed in ABAQUS to predict the behaviour of confined RC columns subjected to the rapid concentric loading. A locally modified stress-strain relation of confined concrete with the strain rate sensitivity of the concrete material and the confining effect of overlapping hoops were proposed to complete the simulation of the dynamic behaviour of concrete with the concrete plastic-constitutive model in ABAQUS. The finite element predictions are consistent with the existing test results. Based on the FEA model, a parametric investigation was conducted to capture more information about the behaviour of confined RC columns under varying loading rates.

  3. Improved concretes for corrosion resistance

    Science.gov (United States)

    1997-07-01

    The deterioration of various reinforced concrete bridge components containing conventional black steel reinforcement is the most important problem facing U.S. highway agencies. A major cause of this concrete deterioration (cracking, delamination, and...

  4. Rapid detailed characterization of concrete shielding blocks utilizing internal natural radionuclides for calibration

    International Nuclear Information System (INIS)

    McDonald, R.J.; Smith, A.R.; Hurley, D.L.; Norman, E.B.; Schoonover, M.R.

    1998-01-01

    Following many years of productive research, the 184-inch Cyclotron, the SuperHILAC, and the BEVALAC accelerators at the Berkeley Laboratory were closed, leaving thousands of concrete shielding blocks available for reuse, recycling, or disposal. The process history of these blocks precludes free release pending radiological characterization. This paper describes a procedure whereby a high efficiency shielded germanium spectrometer is used to rapidly characterize natural and man-made activity within the blocks. The spectrometer is moved up to the block and 5 minutes of data are collected at the point on the block that registers highest on a micro-R meter. Sensitivity is better than 1 pCi/g (0.037 Bq/g) for Co-60 and Eu-152, the prominent man-made activities observed. One-time calibration of the detector system is obtained from a sample of concrete, drilled with a hammer drill, counted in our low-background facility, and compared to crushed rock with known U, Th, and K activity. A simple relationship exists between the counts/minute observed in a characteristic gamma-ray peak and the activity in the block. (author)

  5. Rapid multichannel impact-echo scanning of concrete bridge decks from a continuously moving platform

    Science.gov (United States)

    Mazzeo, Brian A.; Larsen, Jacob; McElderry, Joseph; Guthrie, W. Spencer

    2017-02-01

    Impact-echo testing is a non-destructive evaluation technique for determining the presence of defects in reinforced concrete bridge decks based on the acoustic response of the bridge deck when struck by an impactor. In this work, we build on our prior research with a single-channel impactor to demonstrate a seven-channel impact-echo scanning system with independent control of the impactors. This system is towed by a vehicle and integrated with distance measurement for registering the locations of the impacts along a bridge deck. The entire impact and recording system is computer-controlled. Because of a winch system and hinged frame construction of the apparatus, setup, measurement, and take-down of the apparatus can be achieved in a matter of minutes. Signal processing of the impact responses is performed on site and can produce a map of delaminations immediately after data acquisition. This map can then be used to guide other testing and/or can be referenced with the results of other testing techniques to facilitate comprehensive condition assessments of concrete bridge decks. This work demonstrates how impact-echo testing can be performed in a manner that makes complete bridge deck scanning for delaminations rapid and practical.

  6. Rapid detailed characterization of concrete shielding blocks utilizing internal natural radionuclides for calibration

    International Nuclear Information System (INIS)

    McDonald, R.J.; Smith, A.R.; Norman, E.B.; Cowles, D.

    1995-10-01

    Following many years of productive work, the SuperHILAC and Bevalac accelerators at Lawrence Berkeley National Laboratory were closed, leaving thousands of concrete shielding blocks available for reuse or disposal. The process history of these blocks as shielding precludes free release pending radiological characterization. This paper presents a method for the rapid characterization of gamma-ray-emitting radioisotopes in large samples of earth-like materials: concrete shielding blocks in this case. Active regions are identified with a sensitive radiation-survey instrument and then examined in detail with a high-efficiency lead-shielded Ge spectrometer. Naturally-occurring gamma-ray emissions from the decays of uranium, thorium, and potassium are used to calibrate the spectrometer. A simple relationship exists between the observed counting rate in a characteristic gamma ray and the activity in the block. This method, taking only tens of minutes per sample at the nano-Curie/gram sensitivity level, replaces much of the expensive coring and laboratory analysis methods needed otherwise

  7. Discussion of the evolution of the chloride migration coefficient of Portland cement concrete tested by the rapid chloride migration (RCM) test at long-term curing periods up to 5 years

    NARCIS (Netherlands)

    Yu, Z.; Ye, G.; Hunger, M.; Noort, R.

    2013-01-01

    Chloride-induced corrosion of reinforced concrete is one of the main deterioration mechanisms leading to shortening of the service life of concrete structures. Therefore, assessment of the resistance of concrete to chloride ingress plays an important role in predicting the service life of such

  8. Individualized dosimetry-based activity reduction of {sup 90}Y-DOTATOC prevents severe and rapid kidney function deterioration from peptide receptor radionuclide therapy

    Energy Technology Data Exchange (ETDEWEB)

    Binnebeek, Sofie van; Baete, Kristof; Vanbilloen, Bert; Terwinghe, Christelle; Mortelmans, Luc [University Hospitals Leuven, Nuclear Medicine, Leuven (Belgium); KU Leuven, Department of Imaging and Pathology, Leuven (Belgium); Koole, Michel [University Medical Centre Groningen, Department of Nuclear Medicine, Groningen (Netherlands); Mottaghy, Felix M. [University Hospital Aachen, Department of Nuclear Medicine, Aachen (Germany); Maastricht University Medical Center, Department of Nuclear Medicine, Maastricht (Netherlands); Clement, Paul M. [University Hospitals Leuven, Medical Oncology, Leuven (Belgium); KU Leuven, Laboratory of Experimental Oncology, Leuven (Belgium); Haustermans, Karin [University Hospitals Leuven, Radiation Oncology, Leuven (Belgium); KU Leuven, Department of Oncology, Leuven (Belgium); Cutsem, Eric van; Verslype, Chris [KU Leuven, Department of Oncology, Leuven (Belgium); University Hospitals Leuven, Division of Digestive Oncology, Leuven (Belgium); Verbruggen, Alfons [KU Leuven, Laboratory for Radiopharmacy, Leuven (Belgium); Bogaerts, Kris [KU Leuven, Division of Public Health and Primary Care (I-Biostat), Leuven (Belgium); Deroose, Christophe M. [University Hospitals Leuven, Nuclear Medicine, Leuven (Belgium); KU Leuven, Department of Imaging and Pathology, Leuven (Belgium); UZ Leuven, Nuclear Medicine, Leuven (Belgium)

    2014-06-15

    Assessment of kidney function evolution after {sup 90}Y-DOTATOC peptide receptor radionuclide therapy (PRRT) with capped activity administration based on a 37-Gy threshold of biological effective dose (BED) to the kidney. In a prospective phase II study, patients with metastasized neuroendocrine tumours were evaluated for therapy using 185 MBq {sup 111}In-pentetreotide with amino acid coinfusion. Planar whole-body images were acquired at four time-points after injection and kidney volumes were measured using CT/MRI. BED to the kidneys was estimated using an extended BED formula and biexponential renal clearance. Based on published BED dose-toxicity relationships, we allowed a maximal kidney BED of 37 Gy; if the calculated BED exceeded 37 Gy, treatment activity was reduced accordingly. Kidney function was assessed at baseline and at 18 months, predominantly using {sup 51}Cr-EDTA. The rate of renal function decline was expressed as annual glomerular filtration rate loss (aGFRL). Only 22 of 50 patients reached the 18-months time-point, with most missing patients having died due to disease progression. In the 22 patients who reached 18 months, no rapid kidney function deterioration was observed over the 18 months, aGFRL >33 % was not seen, and only three patients showed an increase of one toxicity grade and one patient an increase of two grades. No significant correlations between kidney volume (p = 0.35), baseline GFR (p = 0.18), risk factors for renal function loss (p = 0.74) and aGFRL were observed. Among the 28 patients who did not reach 18 months, one developed grade 4 kidney toxicity at 15 months after PRRT. Prospective dosimetry using a 37 Gy BED as the threshold for kidney toxicity is a good guide for {sup 90}Y-DOTATOC PRRT and is associated with a low risk of rapid renal function deterioration and evolution to severe nephrotoxicity. (orig.)

  9. Performance Analysis of a Recycled Concrete Interfacial Transition Zone in a Rapid Carbonization Environment

    Directory of Open Access Journals (Sweden)

    Gongbing Yue

    2018-01-01

    Full Text Available Based on the characteristics of recycled concrete interface structures, a multi-interface reconstruction model was established. To study the microstructure evolution of the interfacial transition zone (ITZ during the carbonization process of recycled concrete, the microstructure characteristics of the ITZ of C30, C40, and C50 grade recycled concrete and the mortar matrix before and after carbonization were studied through the microhardness tester and SEM. The results show that the microhardness values of the ITZ and the mortar matrix are obviously increased and that the width of the ITZ decreases, while the ITZ performance of the C50 grade recycled concrete is not significantly changed. The ITZ exhibits a large amount of granular CaCO3 after carbonization, the pores are refined, and microcracks are generated. Overall, there are significant differences in the microstructures between the ITZ and the mortar matrix before and after carbonization.

  10. Capturing early signs of deterioration: the dutch-early-nurse-worry-indicator-score and its value in the Rapid Response System.

    Science.gov (United States)

    Douw, Gooske; Huisman-de Waal, Getty; van Zanten, Arthur R H; van der Hoeven, Johannes G; Schoonhoven, Lisette

    2017-09-01

    of dutch-early-nurse-worry-indicator-score indicators showed higher positive predictive values. Dutch-early-nurse-worry-indicator-score indicators alert in an early stage of deterioration, before reaching the trigger threshold to call a rapid response team and can improve interdisciplinary communication on surgical wards during regular rounds, and when calling for assistance. Dutch-early-nurse-worry-indicator-score structures communication and recording of signs known to be associated with a decline in a patient's condition and can empower nurses to call assistance on the 'worry' criterion in an early stage of deterioration. © 2016 John Wiley & Sons Ltd.

  11. Multi-physics and multi-scale deterioration modelling of reinforced concrete part I: Coupling transport and corrosion at the material scale

    DEFF Research Database (Denmark)

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

    2015-01-01

    is fully coupled, i.e. information, such as temperature and moisture distribution, phase assemblage, corrosion current density, damage state of concrete cover, etc., are continuously exchanged between the models. Although not explicitly outlined in this paper, such an analysis may be further integrated...... models are sketched to describe (i) transport of heat and matter in porous media as well as phase assemblage in hardened Portland cement, (ii) corrosion of reinforcement, and (iii) material performance including corrosion-induced damages on the meso and macro scale. The presented modelling framework...

  12. Rapid chloride permeability test as durability index of the concrete structure

    Directory of Open Access Journals (Sweden)

    Martínez-Sánchez, B.

    2003-12-01

    Full Text Available From the RCPT publication, this test has been frequently used in the concrete structures durability assessment. This test it could be determined in a relatively short time the material permeability, within a rank or quality level that allows comparing concretes as far as their characteristics. In this document, is present an intense investigation to evaluate mix designs with the principal objective to measure the participation and contribution of the components that take part in the concrete manufacture. A detailed review of the components contribution is applied to know specifically the properties in the product during any state: fresh or hard path. In this paper, are identified and included the most influence variables in the concrete properties modification.

    Desde su lanzamiento, la prueba de permeabilidad rápida a la penetración de cloruros ha sido usada frecuentemente en la evaluación de la durabilidad en las estructuras de hormigón, ya que se puede establecer, en un tiempo relativamente corto, la determinación de la permeabilidad del material, dentro de un nivel de calidad que permite comparar hormigones en cuanto a esta característica. En este articulo se presenta una investigación en donde se evalúan diseños de mezcla con la finalidad de medir la participación y contribución de cada uno de los componentes que intervienen en la fabricación del hormigón, revisando con detalle su contribución en las propiedades finales del producto, sin olvidar sus efectos en su comportamiento en estado fresco o cuando se encuentra en fase de endurecimiento. En el trabajo se incluyen e identifican las variables de mayor influencia y su relación con la propiedad que modificaron en el hormigón.

  13. Lunar concrete for construction

    Science.gov (United States)

    Cullingford, Hatice S.; Keller, M. Dean

    1988-01-01

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

  14. Separation and collection of coarse aggregate from waste concrete by electric pulsed power

    Science.gov (United States)

    Shigeishi, Mitsuhiro

    2017-09-01

    Waste concrete accounts for a substantial fraction of construction waste, and the recycling of waste concrete as concrete aggregate for construction is an important challenge associated with the rapid increase in the amount of waste concrete and the tight supply of natural aggregate. In this study, we propose a technique based on the use of high-voltage pulsed electric discharge into concrete underwater for separating and collecting aggregate from waste concrete with minimal deterioration of quality. By using this technique, the quality of the coarse aggregate separated and collected from concrete test specimens is comparable to that of coarse aggregate recycled by heating and grinding methods, thus satisfying the criteria in Japan Industrial Standard (JIS) A 5021 for the oven-dry density and the water absorption of coarse aggregate by advanced recycling.

  15. 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.

  16. Performance of geopolymer concrete in fire

    OpenAIRE

    Zhao, Ren

    2017-01-01

    Portland cement concrete is a world-wide used construction material. However, when Portland cement concrete is exposed to fire, its mechanical properties are deteriorated. The deterioration of concrete is generally caused by the decomposition of the Portland cement hydrate or the thermal incompatibility between cement paste and aggregate. Spalling, which is a violent or non-violent breaking off of layers or pieces of concrete from the surface of a structural element, may also occur when the c...

  17. Capturing early signs of deterioration: the dutch-early-nurse-worry-indicator-score and its value in the Rapid Response System

    NARCIS (Netherlands)

    Douw, G.; Huisman-de Waal, G.J.; Zanten, A.R. van; Hoeven, J.G. van der; Schoonhoven, L.

    2017-01-01

    AIMS AND OBJECTIVES: To determine the predictive value of individual and combined dutch-early-nurse-worry-indicator-score indicators at various Early Warning Score levels, differentiating between Early Warning Scores reaching the trigger threshold to call a rapid response team and Early Warning

  18. Alkaliphilic Bacillus species show potential application in concrete crack repair by virtue of rapid spore production and germination then extracellular calcite formation.

    Science.gov (United States)

    Sharma, T K; Alazhari, M; Heath, A; Paine, K; Cooper, R M

    2017-05-01

    Characterization of alkaliphilic Bacillus species for spore production and germination and calcite formation as a prelude to investigate their potential in microcrack remediation in concrete. Conditions, extent and timing of endospore production was determined by dark-field light microscopy; germination induction and kinetics were assessed by combining reduction in optical density with formation of refractile bodies by phase-contrast microscopy. Bacillus pseudofirmus was selected from several species as the most suitable isolate. Levels and timing of calcium carbonate precipitated in vitro by B. pseudofirmus were evaluated by atomic absorption spectroscopy and structural identity confirmed as calcite and aragonite by Raman spectroscopy and FTIR. The isolate produced copious spores that germinated rapidly in the presence of germinants l-alanine, inosine and NaCl. Bacterial cells produced CaCO 3 crystals in microcracks and the resulting occlusion markedly restricted water ingress. By virtue of rapid spore production and germination, calcium carbonate formation in vitro and in situ, leading to sealing of microcracks, B. pseudofirmus shows clear potential for remediation of concrete on a commercial scale. Microbial sealing of microcracks should become a practicable and sustainable means of increasing concrete durability. © 2017 The Authors. Journal of Applied Microbiology published by John Wiley & Sons Ltd on behalf of The Society for Applied Microbiology.

  19. Mechanical and Permeability Characteristics of Latex-Modified Pre-Packed Pavement Repair Concrete as a Function of the Rapid-Set Binder Content

    Directory of Open Access Journals (Sweden)

    Jae-Woong Han

    2015-10-01

    Full Text Available We evaluated the strength and durability characteristics of latex-polymer-modified, pre-packed pavement repair concrete (LMPPRC with a rapid-set binder. The rapid-set binder was a mixture of rapid-set cement and silica sand, where the fluidity was controlled using a latex polymer. The resulting mix exhibited a compressive strength of ¥21 MPa and a flexural strength of ¥3.5 MPa after 4 h of curing (i.e., the traffic opening term for emergency repairs of pavement. The ratio of latex polymer to rapid-set binder material was varied through 0.40, 0.33, 0.29, and 0.25. Mechanical characterization revealed that the mechanical performance, permeability, and impact resistance increased as the ratio of latex polymer to rapid-set binder decreased. The mixture exhibited a compressive strength of ¥21 MPa after 4 h when the ratio of latex polymer to rapid-set binder material was ¤0.29. The mixture exhibited a flexural strength of ¥3.5 MPa after 4 h when the ratio of latex polymer to rapid-set binder material was ¤0.33. The permeability resistance to chloride ions satisfied 2000 C after 7 days of curing for all ratios. The ratio of latex polymer to rapid-set binder material that satisfied all conditions for emergency pavement repair was ¤0.29.

  20. The Impact of Traffic-Induced Bridge Vibration on Rapid Repairing High-Performance Concrete for Bridge Deck Pavement Repairs

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2014-01-01

    Full Text Available Based on forced vibration tests for high-performance concrete (HPC, the influence of bridge vibration induced by traveling vehicle on compressive strength and durability of HPC has been studied. It is concluded that 1 d and 2 d compressive strength of HPC decreased significantly, and the maximum reduction rate is 9.1%, while 28 d compressive strength of HPC had a slight lower with a 3% maximal drop under the action of two simple harmonic vibrations with 2 Hz, 3 mm amplitude, and 4 Hz, 3 mm amplitude. Moreover, the vibration had a slight effect on the compressive strength of HPC when the simple harmonic vibration had 4 Hz and 1 mm amplitude; it is indicated that the amplitude exerts a more prominent influence on the earlier compressive strength with the comparison of the frequency. In addition, the impact of simple harmonic vibration on durability of HPC can be ignored; this shows the self-healing function of concrete resulting from later hydration reaction. Thus, the research achievements mentioned above can contribute to learning the laws by which bridge vibration affects the properties of concrete and provide technical support for the design and construction of the bridge deck pavement maintenance.

  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. The economy of preventive maintenance of concrete bridges : final report.

    Science.gov (United States)

    2016-03-01

    The most economical approach to maintain existing concrete bridges is by adopting an active preventive maintenance : approach. An in-depth investigation of the combined deterioration effects of various deterioration mechanisms is needed : to establis...

  3. Bridge element deterioration rates.

    Science.gov (United States)

    2008-10-01

    This report describes the development of bridge element deterioration rates using the NYSDOT : bridge inspection database using Markov chains and Weibull-based approaches. It is observed : that Weibull-based approach is more reliable for developing b...

  4. 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.

  5. Evaluation of Shear Resisting Capacity of a Prestressed Concrete Containment Building with Steel or Polyamide Fiber Reinforcement

    International Nuclear Information System (INIS)

    Choun, Youngsun; Park, Junhee

    2014-01-01

    Conventional reinforced concrete (RC) members generally show a rapid deterioration in shear resisting mechanisms under a reversed cyclic load. However, the use of high-performance fiber-reinforced cement composites provides excellent damage tolerance under large displacement reversals compared with regular concrete. Previous experimental studies have indicated that the use of fibers in conventional RC can enhance the structural and functional performance of prestressed concrete containment buildings (PCCBs) in nuclear power plants. This study evaluates the shear resisting capacity for a PCCB constructed using steel fiber reinforced concrete (SFRC) or polyamide fiber reinforced concrete (PFRC). The effects of steel and polyamide fibers on the shear performance of a PCCB were investigated. It was revealed that steel fibers are more effective to enhance the shear resisting capacity of a PCCB than polyamide fibers. The ductility and energy dissipation increase significantly in fiber reinforced PCCBs

  6. Evaluation of Shear Resisting Capacity of a Prestressed Concrete Containment Building with Steel or Polyamide Fiber Reinforcement

    Energy Technology Data Exchange (ETDEWEB)

    Choun, Youngsun; Park, Junhee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Conventional reinforced concrete (RC) members generally show a rapid deterioration in shear resisting mechanisms under a reversed cyclic load. However, the use of high-performance fiber-reinforced cement composites provides excellent damage tolerance under large displacement reversals compared with regular concrete. Previous experimental studies have indicated that the use of fibers in conventional RC can enhance the structural and functional performance of prestressed concrete containment buildings (PCCBs) in nuclear power plants. This study evaluates the shear resisting capacity for a PCCB constructed using steel fiber reinforced concrete (SFRC) or polyamide fiber reinforced concrete (PFRC). The effects of steel and polyamide fibers on the shear performance of a PCCB were investigated. It was revealed that steel fibers are more effective to enhance the shear resisting capacity of a PCCB than polyamide fibers. The ductility and energy dissipation increase significantly in fiber reinforced PCCBs.

  7. Cable deterioration analysis method

    International Nuclear Information System (INIS)

    Sugiyama, Masahiko; Nitta, Makoto.

    1997-01-01

    At first, a hardness of a minute region and an elongation at break are measured relative to a plurality of reference samples having deterioration which is different stepwise, to obtain a relation between the hardness of the minute region and the elongation at break. They are obtained as information of correlation showing the degree of deterioration of cables. Then, samples are collected. The samples are collected from a PVC sheath. In this case, the samples to be used for the measurement are extremely small piece having the size of one side of about several hundred μm. Then, the hardness of the minute region of the samples is measured. The measured hardness of the minute region is corresponded to the previously obtained information of the correlation for deteriorations to judge the state of deterioration for the collected samples. With such procedures, the state of deterioration for electric wires and cables to be used in nuclear facilities such as power plants can easily be diagnosed substantially non destructively. (I.N.)

  8. A novel abutment construction technique for rapid bridge construction : controlled low strength Materials (CLSM) with full-height concrete panels.

    Science.gov (United States)

    2012-01-01

    One of the major obstacles facing rapid bridge construction for typical span type bridges is the time required to construct bridge abutments and foundations. This can be remedied by using the controlled low strength materials (CLSM) bridge abutment. ...

  9. Visualising Deteriorating Conditions

    Directory of Open Access Journals (Sweden)

    Tom Andrews, RN, B.Sc. (Hons, M.Sc., Ph.D.

    2005-03-01

    Full Text Available The research aims were to investigate the difficulties ward staff experienced in detecting deterioration and how these were resolved. The emphasis within the literature tends to be on identifying premonitory signs that may be useful in predicting deterioration. Changes in respiratory rate is the most consistent of these (Fieselmann et al. 1993; Sax and Charlson 1987; Schein et al. 1990; Smith and Wood 1998 but in common with other signs, it lacks sensitivity and specificity. The sample consisted of 44 nurses, doctors (Interns and health care support workers from a general medical and surgical ward. Data were collected by means of nonparticipant observations and interviews, using grounded theory as originated by (Glaser and Strauss 1967 and (Glaser 1978. As data were collected, the constant comparative method and theoretical sensitivity were used as outlined in grounded theory. A core category of “visualising deteriorating conditions” emerged, together with its sub-core categories of “intuitive knowing”, “baselining” and “grabbing attention”.The main concern in visualising deteriorating conditions is to ensure that patients suspected of deterioration are successfully referred to medical staff. The aim is to convince those who can treat or prevent further deterioration to intervene. Through intuitive knowing they pick up that patients have changed in a way that requires a medical assessment. To make the referral more credible, nurses attempt to contextualise any changes in patients by baselining (establishing baselines. Finally with the backup of colleagues, nurses refer patients by providing as much persuasive information as possible in a way that grabs attention. The whole process is facilitated by knowledge and experience, together with mutual trust and respect.

  10. TRANSPARENT CONCRETE

    OpenAIRE

    Sandeep Sharma*, Dr. O.P. Reddy

    2017-01-01

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

  11. Corrosion resistant alloys for reinforced concrete [2009

    Science.gov (United States)

    2009-04-01

    Deterioration of concrete bridges because of reinforcing steel corrosion has been recognized for four-plus decades as a major technical and economic challenge for the United States. As an option for addressing this problem, renewed interest has focus...

  12. Corrosion resistant alloys for reinforced concrete [2007

    Science.gov (United States)

    2007-07-01

    Deterioration of concrete bridges because of reinforcing steel corrosion has been recognized for 4-plus decades as a major technical and economic challenge for the United States. As an option for addressing this problem, renewed interest has focused ...

  13. How Concrete is Concrete

    OpenAIRE

    Koeno Gravemeijer

    2010-01-01

    If we want to make something concrete in mathematics education, we are inclined introduce, what we call, ‘manipulatives’, in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own, abstract, knowledge; in the latter, we try to find an example that the others will be familiar with. This article first looks at the tension between these two diff...

  14. Advances in Modeling Concrete Service Life : Proceedings of 4th International RILEM PhD Workshop

    CERN Document Server

    Gulikers, Joost

    2012-01-01

    In this book, a critical analysis is made on service life models related to reinforcement corrosion. The contributors are on the frontier of knowledge in the field of durability of reinforced concrete. Topics covered in the book include: causes and mechanisms of deterioration, transport mechanisms in concrete, numerical modeling of concrete behavior, durability modeling and prediction, reliability approach to structural design for durability, structural behavior following degradation of concrete structures, deterioration and repair of concrete structures, and corrosion measurement techniques.

  15. 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

  16. Durability evaluation method on rebar corrosion of reinforced concrete

    International Nuclear Information System (INIS)

    Kitsutaka, Yoshinori

    2013-01-01

    In this paper, method on the durability evaluation in nuclear power plant concrete structures was investigated. In view of the importance of evaluating the degree of deterioration of reinforced concrete structures, relationships should be formulated among the number of years elapsed, t, the amount of action of a deteriorative factor, F, the degree of material deterioration, D, and the performance of the structure, P. Evaluation by PDFt diagrams combining these relationships may be effective. A detailed procedure of durability evaluation for a reinforced concrete structure using PDFt concept is presented for the deterioration of rebar corrosion caused by neutralization and penetration of salinity by referring to the recent papers. (author)

  17. Remittances Deteriorate Governance

    OpenAIRE

    Faisal Z. Ahmed

    2013-01-01

    I use a natural experiment of oil-price-driven remittance flows to poor, non-oil-producing Muslim countries to demonstrate that remittances deteriorate the quality of governance, especially in countries with weak democratic institutions. The results indicate that a 1 standard deviation increase in remittances raises corruption by 1.5 index points (on a 6-point scale), which is equivalent to a [dollar]600 decrease in per capita GDP. Concomitantly, remittances may enable governments to reduce t...

  18. Aging Evaluation of Nuclear Power Plant Concrete Structures

    International Nuclear Information System (INIS)

    Kitsutaka, Y.; Takesue, N.; Tsukagoshi, M.

    2012-01-01

    In this paper, method on the aging evaluation in nuclear power plant concrete structures was investigated. Problems on the durability evaluation of reinforced concrete structures were pointed out and an evaluation framework was considered. In view of the importance of evaluating the degree of deterioration of reinforced concrete structures, relationships should be formulated among the number of years elapsed, t, the amount of action of a deteriorative factor, F, the degree of material deterioration, D, and the performance of the structure, P. Evaluation by PDFt diagrams combining these relationships may be effective. A detailed procedure of durability evaluation for a reinforced concrete structure using PDFt concept is presented for the deterioration factors of thermal effect, irradiation, neutralization and penetration of salinity by referring to the recent papers. And the evaluation framework of the deteriorated material constitutive model which can be used for the numerical analysis of the integrity evaluation for the concrete structure was proposed. (author)

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  20. Re-Assessment of Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper two aspects of re-assessment of the reliability of concrete bridges are discussed namely modelling of the corrosion of reinforcement and updating of uncertain variables. The main reason for deterioration of concrete bridges is corrosion of the reinforcement. Therefore, modelling...

  1. Evaluation of concrete inlay for continuously reinforced concrete pavement rehabilitation.

    Science.gov (United States)

    2010-06-01

    In 1996, WisDOT constructed a concrete inlay test section on I43 in Manitowoc County. The existing pavement was CRCP constructed in 1978 and was badly deteriorated with punchouts. In the area of the 2777foot test section, the existing paveme...

  2. Ageing of portland cement concrete cured under moist conditions

    NARCIS (Netherlands)

    Yu, Z.; Ye, G.; Van Breugel, K.; Chen, W.

    2014-01-01

    Deterioration of microstructure in cement concrete will cause changes in the transport properties of the concrete. Transport properties at different ages of the concrete provide information about the microstructural changes of the material. A way to measure the transport properties, i.e. the

  3. Sodium concrete reaction - Structural considerations

    International Nuclear Information System (INIS)

    Ferskakis, G.N.

    1984-01-01

    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-structuralchemical 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

  4. How Concrete is Concrete?

    Directory of Open Access Journals (Sweden)

    Koeno Gravemeijer

    2011-01-01

    Full Text Available If we want to make something concrete in mathematics education, we are inclined introduce, what we call, ‘manipulatives’, in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own, abstract, knowledge; in the latter, we try to find an example that the others will be familiar with. This article first looks at the tension between these two different ways of making things concrete. Next another role of manipulatives, will be discussed, namely that of means for scaffolding and communication. In this role, manipulatives may function as means of support in a process that aims at helping students to build on their own thinking while constructing more sophisticated mathematics.Key words:  Conceret Learning Materials, School Math, Common Sense, Scaffolding, Communication DOI: http://dx.doi.org/10.22342/jme.2.1.780.1-14

  5. Durability of precast prestressed concrete piles in marine environment : reinforcement corrosion and mitigation - Part 1.

    Science.gov (United States)

    2011-06-01

    Research conducted in Part 1 has verified that precast prestressed concrete piles in : Georgias marine environment are deteriorating. The concrete is subjected to sulfate and : biological attack and the prestressed and nonprestressed reinforcement...

  6. Void structure of concrete with superabsorbent polymers and its relation to frost resistance of concrete

    DEFF Research Database (Denmark)

    Hasholt, Marianne Tange; Jensen, Ole Mejlhede; Laustsen, Sara

    2013-01-01

    the difference between poor and satisfactory frost-resistance. Furthermore, the results indicate that voids created directly by SAP protect concrete against frost deterioration just like other air voids; if the concrete contains enough SAP voids, these alone can provide sufficient frost resistance. © 2013 RILEM....

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

    Science.gov (United States)

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

    2017-11-01

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

  8. Rapid Strengthening of Full-Sized Concrete Beams with Powder-Actuated fastening Systems and Fiber-Reinforced Polymer (FRP) Composite Materials

    National Research Council Canada - National Science Library

    Bank, Lawrence

    2002-01-01

    A research study was conducted to determine if the method of retrofitting reinforced concrete beams with powder-actuated fasteners and composite materials was applicable to full-scale flexural members...

  9. A review on carbonation study in concrete

    Science.gov (United States)

    Venkat Rao, N.; Meena, T.

    2017-11-01

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

  10. Pervious Concrete

    OpenAIRE

    Torsvik, Øyvind André Hoff

    2012-01-01

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

  11. 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....

  12. Sustainable monitoring of concrete structures : strength and durability performance of polymer-modified self-sensing concrete

    OpenAIRE

    Torgal, Fernando Pacheco; Gonzalez, J.; Jalali, Said

    2012-01-01

    Concrete structures all over the world are reaching the end of their service life sooner than expected. This is due to the fact that ordinary Portland cement-based concrete deteriorates under environmental actions and also that structural inspections and conservation actions are expensive. Besides, as they consume energy and non-renewable resources, they have negative environmental impacts. Self-sensing concrete provides an alternative way of monitoring concrete-reinforced structures...

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

    Science.gov (United States)

    Sun, Hongbin; Pashoutani, Sepehr; Zhu, Jinying

    2018-06-16

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

  14. Glazed Concrete

    DEFF Research Database (Denmark)

    Bache, Anja Margrethe

    2010-01-01

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

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

    DEFF Research Database (Denmark)

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

    2006-01-01

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

  16. Concrete Hinges

    DEFF Research Database (Denmark)

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

    2014-01-01

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

  17. Concrete structures

    CERN Document Server

    Setareh, Mehdi

    2017-01-01

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

  18. Impact of biofouling on corrosion resistance of reinforced concrete

    Digital Repository Service at National Institute of Oceanography (India)

    Patil, B.T.; Gajendragad, M.R.; Ranganna, G.; Wagh, A.B.; Sudhakaran, T.

    the structure from deterioration; a nonuniform deposit can lead to severe localized pitting corrosion. To study this cylindrical reinforced concrete electrodes were exposed to seawater. They were periodically removed and examined for the presence of fouling...

  19. Rapid analysis of 14C and 3H in graphite and concrete for decommissioning of nuclear reactor

    DEFF Research Database (Denmark)

    Hou, Xiaolin

    2005-01-01

    /g graphite and 0.11 and 0.06Bq/g concrete, respectively. The cross contamination of C-14 and tritium in the preparation of samples is less than 0.2%. The interference of other radionuclides in the determination of C-14 and tritium in graphite is insignificant. The analytical accuracy, investigated...

  20. Effects of curing methods and supplementary cementitious material use on freeze thaw durability of concrete containing d-cracking aggregates.

    Science.gov (United States)

    2013-12-01

    For concrete pavements in Kansas, the most effective method of increasing their sustainability is to : increase the service life. One of the principle mechanisms of concrete pavement deterioration in Kansas is : freezing and thawing damage. Some Kans...

  1. Reviewing the Carbonation Resistance of Concrete

    Directory of Open Access Journals (Sweden)

    S P Singh

    2016-07-01

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

  2. Concrete Fibrations

    OpenAIRE

    Pagnan, Ruggero

    2017-01-01

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

  3. Effects of Reinforcing Fiber and Microsilica on the Mechanical and Chloride Ion Penetration Properties of Latex-Modified Fiber-Reinforced Rapid-Set Cement Concrete for Pavement Repair

    Directory of Open Access Journals (Sweden)

    Woong Kim

    2018-01-01

    Full Text Available This study evaluated the influence of reinforcement fiber type and microsilica content on the performance of latex-modified fiber-reinforced roller-compacted rapid-hardening cement concrete (LMFRCRSC for a concrete pavement emergency repair. Experimental variables were the microsilica substitution ratio (1, 2, 3, and 4%, and the reinforcement fiber (jute versus macrosynthetic fiber. In the tests, compressive, flexural, and splitting tensile strength; chloride ion penetration resistance; and abrasion resistance were assessed. From the compressive and flexural strength tests with microsilica substitution, the 4-hour curing strength decreased as the microsilica substitution ratio increased. From the chloride ion penetration test, as the microsilica substitution ratio increased, chloride ion penetration decreased. The abrasion resistances increased with the substitution ratio of microsilica increase. Based on these test results, microsilica at a substitution ratio of 3% or less and macrosynthetic fiber as the reinforcement improved the performance of LMFRCRSC for a concrete pavement emergency repair and satisfied all of the target strength requirements.

  4. Method on the aging evaluation in nuclear power plant concrete structures

    International Nuclear Information System (INIS)

    Kitsutaka, Yoshinori; Tsukagoshi, Masayuki

    2014-01-01

    In this paper, method on the durability evaluation in nuclear power plant concrete structures was investigated. In view of the importance of evaluating the degree of deterioration of reinforced concrete structures, relationships should be formulated among the number of years elapsed, t, the amount of action of a deteriorative factor, F, the degree of material deterioration, D, and the performance of the structure, P. Evaluation by PDFt diagrams combining these relationships may be effective. A detailed procedure of durability evaluation for a reinforced concrete structure using PDFt concept is presented for the deterioration factors of thermal effect, irradiation, neutralization and penetration of salinity by referring to the recent papers

  5. NANOMODIFIED CONCRETE

    Directory of Open Access Journals (Sweden)

    B. M. Khroustalev

    2015-01-01

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

  6. 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 test...... 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....

  7. Application of AE to evaluate deterioration of prt and harbor structures

    International Nuclear Information System (INIS)

    Matsuyama, Kimitoshi; Ishibashi, Akichika; Fujiwara, Tetsuro; Kanemoto, Yasuhiro; Hamada, Shigenori; Ohtsu, Masayasu

    1997-01-01

    The degree of concrete deterioration is normally evaluated by uniaxial compression tests of core samples taken from existing concrete structures. The uniaxial compression test can give details on concrete strength, elastic modulus and so forth. By using AE(acoustic emission) technique with uniaxial compression tests, we can get more useful information on interior failures of the core sample. The observation of AE activity was conducted during uniaxial compression tests of concrete specimens and samples. The specimens were cast with 5, 10, 15 and 20% air content. The samples were taken from 2 harbor sites in Japan. Generating behavior of AE was studied quantitatively on the basis of rate process theory. Distribution of pores in the concrete could be measured by the porosimeter. The relation between AE activity in the uniaxial compression test of core samples and concrete property is clarified.

  8. Experimental investigation of the relation between damage at the concrete-steel interface and initiation of reinforcement corrosion in plain and fibre reinforced concrete

    DEFF Research Database (Denmark)

    Michel, Alexander; Solgaard, Anders Ole Stubbe; Pease, Bradley Justin

    2013-01-01

    Cracks in covering concrete are known to hasten initiation of steel corrosion in reinforced concrete structures. To minimise the impact of cracks on the deterioration of reinforced concrete structures, current approaches in (inter)national design codes often limit the concrete surface crack width....... Recent investigations however, indicate that the concrete-reinforcement interfacial condition is a more fundamental criterion related to reinforcement corrosion. This work investigates the relation between macroscopic damage at the concrete-steel interface and corrosion initiation of reinforcement...... embedded in plain and fibre reinforced concrete. Comparisons of experimental and numerical results indicate a strong correlation between corrosion initiation and interfacial condition....

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

    International Nuclear Information System (INIS)

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

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

  10. The Service Life Evaluation for Concrete Structure of NPP

    International Nuclear Information System (INIS)

    Lee, Choon Min; Kim, Seong Soo; Bae, Sung Hwan; Sik, Yoon Eui

    2014-01-01

    Prolonged exposure to the marine environment degrades the durability of concrete and shortens the service life of concrete due to degradation factors such as chloride, carbonation, freezing and thawing, sulfate. Therefore, many country's organizations like the Korea Concrete Institute (KCI), the American Concrete Institute (ACI), the International Federation for Structural Concrete (FIB), the American Society for Testing and Material (ASTM) which recognized the seriousness of this deterioration proposed equation models to evaluate the service life for the concrete structures. As a result, this paper is to especially consider the service life evaluation using these equation models for concrete structure of NPP in Korea compared with 60 years as a design service life. The concrete durability evaluation for Shin-Hanul NPP units 1 and 2 is carried out by using typically proposed assessment models in domestic and foreign standard. It is confirmed that the service life of concrete durability for each of deterioration factors is significantly higher than 60 years as a design service life. As a result, the study of combined deterioration for the concrete structures of NPP in future is positively necessary and maintenance control through regular monitoring should be conducted to secure safety margin basis

  11. Estimation of the Service Lifetime of Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper estimation of the service lifetime of concrete bridges is discussed. The main reason for deterioration of concrete bridges is corrosion of the reinforcement. Therefore, modelling of the corrosion process is an important aspect of the estimation of the service lifetime. In this paper...

  12. Bacteria-based self-healing concrete : An introduction

    NARCIS (Netherlands)

    Mors, R.M.; Jonkers, H.M.

    2012-01-01

    Crack formation in concrete is common, but a typical phenomenon related to durability. Percolation of cracks may lead to leakage problems or ingress of deleterious materials, causing deterioration of the concrete matrix or corrosion of embedded steel reinforcement. Durability can be enhanced by

  13. Failure Modes in Concrete Repair Systems due to Ongoing Corrosion

    NARCIS (Netherlands)

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

    2017-01-01

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

  14. Bacteria-based self-healing concrete for application in the marine environment

    NARCIS (Netherlands)

    Palin, D.; Wiktor, V.; Jonkers, H.M.

    2013-01-01

    Marine concrete structures are exposed to one of the most hostile of natural environments. Many physical and chemical phenomena are usually interdependent and mutually reinforcing in the deterioration of marine exposed concrete: expansion and microcracking due to physical effects increases concrete

  15. Effective Prevention of Oxidative Deterioration of Fish Oil: Focus on Flavor Deterioration.

    Science.gov (United States)

    Miyashita, Kazuo; Uemura, Mariko; Hosokawa, Masashi

    2018-03-25

    Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), both abundant in fish oil, are known to have significant biochemical and physiological effects primarily linked to the improvement of human health, especially cardiovascular and brain health. However, the incorporation of fish oil into foods and beverages is often challenging, as fish oil is very easily oxidized and can cause undesirable flavors. This review discusses this rapid formation of the fishy and metallic off-flavors, focusing especially on an early stage of fish oil oxidation. Although oxidative stability and quality of commercialized fish oil have improved over the past few years, there is a still a problem with its application: Flavor deterioration can be found even at very low oxidation levels. This review also notes the effective way to inhibit the formation of the volatile compounds responsible for the flavor deterioration.

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

    Science.gov (United States)

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

    2018-07-05

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

  17. Concrete domains

    OpenAIRE

    Kahn, G.; Plotkin, G.D.

    1993-01-01

    This paper introduces the theory of a particular kind of computation domains called concrete domains. The purpose of this theory is to find a satisfactory framework for the notions of coroutine computation and sequentiality of evaluation.

  18. Lifetime Reliability Assessment of Concrete Slab Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    A procedure for lifetime assesment of the reliability of short concrete slab bridges is presented in the paper. Corrosion of the reinforcement is the deterioration mechanism used for estimating the reliability profiles for such bridges. The importance of using sensitivity measures is stressed....... Finally the produce is illustrated on 6 existing UK bridges....

  19. Durability as integral characteristic of concrete

    Science.gov (United States)

    Suleymanova, L. A.; Pogorelova, I. A.; Suleymanov, K. A.; Kirilenko, S. V.; Marushko, M. V.

    2018-03-01

    The carried-out research provides insight into the internal bonds energy in material as the basis of its durability, deformability, integrity and resistance to different factors (combined effects of external loadings and (or) environment), into the limits of technical possibilities, durability and physical reality of the process of concrete deterioration, which allows designing reliable and cost-effective ferroconcrete constructions for different purposes.

  20. Corrosion and Cracking of Reinforced Concrete

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    Modelling of the deterioration of reinforced concrete has in recent years changed from being a deterministic modelling based on experience to be stochastic modelling based on sound and consistent physical, chemical and mechanical principles. In this paper is presented a brief review of modern mod...... for time to initial corrosion, time to initial cracking, and time to a given crack width may be obtained....

  1. Photocatalyticpaving concrete

    OpenAIRE

    Lyapidevskaya Ol'ga Borisovna; Fraynt Mikhail Aleksandrovich

    2014-01-01

    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 t...

  2. 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.

  3. 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 ...

  4. Alkali aggregate reactivity in concrete structures in western Canada

    International Nuclear Information System (INIS)

    Morgan, D.R.; Empey, D.

    1989-01-01

    In several regions of Canada, particularly parts of Ontario, Quebec and the Maritime Provinces, research, testing and evaluation of aged concrete structures in the field has shown that alkali aggregate reactivity can give rise to pronounced concrete deterioration, particularly in hydraulic structures subjected to saturation or alternate wetting and drying such as locks, dams, canals, etc. Concrete deterioration is mainly caused by alkali-silica reactions and alkali-carbonate reactions, but a third type of deterioration involves slow/late expanding alkali-silicate/silica reactivity. The alkalies NaOH and KOH in the concrete pore solutions are mainly responsible for attack on expansive rocks and minerals in concrete. Methods for evaluating alkali-aggregate reaction potential in aggregates, and field and laboratory methods for detecting deterioration are discussed. Examples of alkali-aggregate reactions in structures is western Canada are detailed, including a water reservoir at Canadian Forces Base Chilliwack in British Columbia, the Oldman River diversion and flume, the Lundbreck Falls Bridge, and the St Mary's Reservoir spillway, all in southern Alberta. Mitigative measures include avoidance of use of suspect aggregates, but if this cannot be avoided it is recommended to keep the total alkalies in the concrete as low as possible and minimize opportunities for saturation of concrete by moisture. 16 refs., 19 figs., 1 tab

  5. Effects of curing methods and supplementary cementitious material use on freeze thaw durability of concrete containing d-cracking aggregates : [technical summary].

    Science.gov (United States)

    2013-12-01

    For concrete pavements in Kansas, the most effective method of increasing their sustainability is to increase the service life. One of the principle mechanism of concrete pavement deterioration in Kansas is freezing and thawing damage. Some Kansas li...

  6. 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.

  7. Prehospital neurological deterioration in stroke.

    Science.gov (United States)

    Slavin, Sabreena J; Sucharew, Heidi; Alwell, Kathleen; Moomaw, Charles J; Woo, Daniel; Adeoye, Opeolu; Flaherty, Matthew L; Ferioli, Simona; McMullan, Jason; Mackey, Jason; De Los Rios La Rosa, Felipe; Martini, Sharyl; Kissela, Brett M; Kleindorfer, Dawn O

    2018-04-27

    Patients with stroke can experience neurological deterioration in the prehospital setting. We evaluated patients with stroke to determine factors associated with prehospital neurological deterioration (PND). Among the Greater Cincinnati/Northern Kentucky region (population ~1.3 million), we screened all 15 local hospitals' admissions from 2010 for acute stroke and included patients aged ≥20. The GCS was compared between emergency medical services (EMS) arrival and hospital arrival, with decrease ≥2 points considered PND. Data obtained retrospectively included demographics, medical history and medication use, stroke subtype (eg, ischaemic stroke (IS), intracerebral haemorrhage (ICH), subarachnoid haemorrhage (SAH)) and IS subtype (eg, small vessel, large vessel, cardioembolic), seizure at onset, time intervals between symptom onset, EMS arrival and hospital arrival, EMS level of training, and blood pressure and serum glucose on EMS arrival. Of 2708 total patients who had a stroke, 1092 patients (median (IQR) age 74 (61-83) years; 56% women; 21% black) were analysed. PND occurred in 129 cases (12%), including 9% of IS, 24% of ICH and 16% of SAH. In multivariable analysis, black race, atrial fibrillation, haemorrhagic subtype and ALS level of transport were associated with PND. Haemorrhage and atrial fibrillation is associated with PND in stroke, and further investigation is needed to establish whether PND can be predicted. Further studies are also needed to assess whether preferential transport of patients with deterioration to hospitals equipped with higher levels of care is beneficial, identify why race is associated with deterioration and to test therapies targeting PND. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  8. Experiment Analysis of Concrete’s Mechanical Property Deterioration Suffered Sulfate Attack and Drying-Wetting Cycles

    Directory of Open Access Journals (Sweden)

    Wei Tian

    2017-01-01

    Full Text Available The mechanism of concrete deterioration in sodium sulfate solution is investigated. The macroperformance was characterized via its apparent properties, mass loss, and compressive strength. Changes in ions in the solution at different sulfate attack periods were tested by inductively coupled plasma (ICP. The damage evolution law, as well as analysis of the concrete’s meso- and microstructure, was revealed by scanning electron microscope (SEM and computed tomography (CT scanning equipment. The results show that the characteristics of concrete differed at each sulfate attack period; the drying-wetting cycles generally accelerated the deterioration process of concrete. In the early sulfate attack period, the pore structure of the concrete was filled with sulfate attack products (e.g., ettringite and gypsum, and its mass and strength increased. The pore size and porosity decreased while the CT number increased. As deterioration progressed, the swelling/expansion force of products and the salt crystallization pressure of sulfate crystals acted on the inner wall of the concrete to accumulate damage and accelerate deterioration. The mass and strength of concrete sharply decreased. The number and volume of pores increased, and the pore grew more quickly resulting in initiation and expansion of microcracks while the CT number decreased.

  9. Development of deterioration models and tests of structural materials for nuclear containment structures(III)

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Byung Hwan [Seoul National University, Seoul (Korea)

    2002-03-01

    The nuclear containment structures are very important infrastructures which require much cost for construction and maintenance. If these structures lose their functions and do not ensure their safety, great losses of human lives and properties will result. Therefore, the nuclear containment structures should secure appropriate safety and functions during these service lives. The nuclear concrete structures start to experience deterioration due to severe environmental condition, even though the concrete structures exhibit generally superior durability. It is, therefore, necessary to take appropriate actions at each stage of planning, design and construction to secure safety and functionability. Thorough examination of deterioration mechanism and comprehensive tests have been conducted to explore the durability characteristics of nuclear concrete structures. 88 refs., 70 figs., 12 tabs. (Author)

  10. Concrete durability

    OpenAIRE

    Gaspar Tébar, Demetrio

    1991-01-01

    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 rese...

  11. Nuclear Power Plant Concrete Structures

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-01-01

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

  12. 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

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

    International Nuclear Information System (INIS)

    Monteiro, P.J.M.; Moehle, J.P.

    1995-12-01

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

  14. Molecular analysis of differentially expressed genes during postharvest deterioration in cassava (Manihot esculenta Crantz) tuberous roots

    NARCIS (Netherlands)

    Huang, J.; Bachem, C.W.B.; Jacobsen, E.; Visser, R.

    2001-01-01

    One of the major problems for cassava is the rapid deterioration after harvesting cassava tuberous roots, which limits the possibilities for production and distribution of cassava in the world. Postharvest deterioration is an inherent problem for cassava since wounding and mechanical damage of the

  15. Reversing the Cycle of Deterioration in the Nation's Public School Buildings

    Science.gov (United States)

    Council of the Great City Schools, 2014

    2014-01-01

    Across the nation, large urban school districts are experiencing premature and rapidly accelerating deterioration of school buildings. The conditions of buildings and equipment, most importantly in classrooms and school support spaces, are deteriorating to the point of hindering the core mission of schools: educating children. This report is the…

  16. Impact Capacity Reduction in Railway Prestressed Concrete Sleepers with Surface Abrasions

    Science.gov (United States)

    Ngamkhanong, Chayut; Li, Dan; Kaewunruen, Sakdirat

    2017-10-01

    Railway sleepers (also called ‘railroad tie’ in North America) embedded in ballasted railway tracks are a main part of railway track structures. Its important role is to transfer the loads evenly from the rails to a wider area of ballast bed and to secure rail gauge and enable safe passages of rolling stocks. By nature, railway infrastructure is nonlinear, evidenced by its behaviours, geometry and alignment, wheel-rail contact and operational parameters such as tractive efforts. Based on our critical review, the dynamic behaviour of railway sleepers has not been fully investigated, especially when the sleepers are deteriorated by excessive wears. In fact, the ballast angularity causes differential abrasions on the soffit or bottom surface of sleepers (especially at railseat zone). Furthermore, in sharp curves and rapid gradient change, longitudinal and lateral dynamics of rails increase the likelihood of railseat abrasions in concrete sleepers due to the unbalanced loading conditions. This paper presents a structural capacity of concrete sleepers under dynamic transient loading. The modified compression field theory for ultimate strength design of concrete sleepers under impact loading will be highlighted in this study. The influences of surface abrasions, including surface abrasion and soffit abrasion, on the dynamic behaviour of prestressed concrete sleepers, are firstly highlighted. The outcome of this study will improve the rail maintenance and inspection criteria in order to establish appropriate and sensible remote track condition monitoring network in practice. Moreover, this study will also improve the understanding of the fundamental dynamic behaviour of prestressed concrete sleepers with surface abrasions. The insight into these behaviours will not only improve safety and reliability of railway infrastructure but will enhance the structural safety of other concrete structures.

  17. Deterioration of flood affected Queensland roads – An investigative study

    Directory of Open Access Journals (Sweden)

    Masuda Sultana

    2016-11-01

    Full Text Available The aim of this paper was to investigate the impact of recent flooding events on the structural and surface condition (such as roughness and rutting of the pavements of the Department of Transport and Main Roads, Queensland, and the Brisbane City Council. The paper also reviewed the major flooding and cyclone events that occurred in the last six years in Queensland. Generally, a rapid increase in deterioration of the structural and surface conditions such as roughness and rutting was observed in pavements after the flood as a result of the inundation. An increasing need for road rehabilitation was also observed after the recent flooding events from 2010 to 2015 in Queensland. Assessing the rapid deterioration of the structural and surface condition of the flood affected pavements is a prerequisite for the accurate prediction of pavement performance, a better decision making process and the management of these roads. Although this paper did not include any model for roughness and rutting, deterioration models for roughness and rutting of flood affected pavements are currently being developed as a part of the future scope of this research. Keywords: Pavement deterioration, Flooding, Structural and surface condition

  18. Surface deterioration of ammonium acid phthalate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Barrus, D.M.; Blake, R.L.; Burek, A.J.

    1976-01-01

    In working with various acid phthalate crystals for low energy X-ray spectroscopy, we have observed a relatively rapid surface degradation of ammonium acid phthalate in comparison with similar crystals was observed. It was found that two different samples degraded in a few days upon exposure to high vacuum (10/sup -6/ - 10/sup -7/ torr). The same crystals showed similar effects when exposed to room atmosphere for two to three weeks. One of these crystals deteriorated while kept constantly in a desiccator jar for about two years. The desiccator environment seems to be the most favorable. The observed difference in the surface of these crystals might be described as a change from a transparent, glasslike condition to a white, powderlike haze somewhat akin to frosted glass. A two week exposure to vacuum for a freshly cleaved crystal caused the integrated coefficient of reflection at 23.6 A to decrease by a factor of 2.5. The degraded surface areas tend to form definite rhombohedral patterns. Since the external symmetry of ammonium acid phthalate crystals is rhombohedral, this suggests that the degradation we observe takes place in the form of large etched figures. A possible mechanism may be sublimation, which would proceed more rapidly in vacuum than in air. It is concluded that ammonium acid phthalate should be kept in a desiccator environment as much as possible. Exposures to vacuum should be brief and critical diffraction measurements should be done using a freshly cleaved surface.

  19. High Performance Concrete

    Directory of Open Access Journals (Sweden)

    Traian Oneţ

    2009-01-01

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

  20. THE STUDY ON THE DURABILITY OF SUBMERGED STRUCTURE DISPLACEMENT DUE TO CONCRETE FAILURE

    Directory of Open Access Journals (Sweden)

    M. Mohd

    2016-09-01

    Full Text Available Concrete structures that exposed to marine environments are subjected to multiple deterioration mechanisms. An overview of the existing technology for submerged concrete, pressure resistant, concrete structures which related such as cracks, debonds, and delamination are discussed. Basic knowledge related to drowning durability such as submerged concrete structures in the maritime environment are the durability of a concrete and the ability to resist to weathering, chemical attack, abrasion or other deterioration processes. The measuring techniques and instrumentation for geometrical monitoring of submerged structural displacements have traditionally been categorized into two groups according to the two main groups, namely as geodetic surveying and geotechnical structural measurements of local displacements. This paper aims to study the durability of submerged concrete displacement and harmful effects of submerged concrete structures.

  1. Gates Precast Concrete User Project Phase 1

    Energy Technology Data Exchange (ETDEWEB)

    Love, Lonnie J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Post, Brian K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Roschli, Alex C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Chesser, Phillip C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-09-01

    The primary objective of the project was to demonstrate the viability of using carbon fiber reinforced ABS plastic and the Big Area Additive Manufacturing (BAAM) technology to rapidly manufacture molds for the precast concrete industry.

  2. Concrete spirituality

    OpenAIRE

    Kritzinger, Johannes N.J.

    2014-01-01

    This article reflects on a number of liturgical innovations in the worship of Melodi ya Tshwane, an inner-city congregation of the Uniting Reformed Church in Southern Africa (URCSA). The focus of the innovations was to implement the understanding of justice in Article 4 of the Confession of Belhar, a confessional standard of the URCSA. The basic contention of the article is that well designed liturgies that facilitate experiences of beauty can nurture a concrete spirituality to mobilise urba...

  3. Evaluation of concrete pavements with materials-related distress : appendix B.

    Science.gov (United States)

    2010-02-02

    An evaluation of cores sampled from six concrete pavements was performed. Factors contributing to pavement distress observed in the field were determined, including expansive alkali-silica reactivity and freeze-thaw deterioration related to poor entr...

  4. Evaluation of concrete pavements with materials-related distress : appendix C.

    Science.gov (United States)

    2010-03-02

    An evaluation of cores sampled from six concrete pavements was performed. Factors contributing to pavement distress observed in the field were determined, including expansive alkali-silica reactivity and freeze-thaw deterioration related to poor entr...

  5. Tension Pneumocephalus with Diplegia and Deterioration of Consciousness

    Directory of Open Access Journals (Sweden)

    Harald Prüss

    2011-02-01

    Full Text Available Tension pneumocephalus results from intracranial air under pressure as a rare complication after head injury or craniofacial surgery. A 58-year-old man underwent ethmoid sinus surgery and subsequently developed rapidly progressive global headache, restlessness, diplegia with sensory loss, and deterioration of the conscious level. A head CT demonstrated extensive pneumocephalus with gross compression of the brain. The frontal retention of air caused widening of the interhemispheric fissure leading to a peaked appearance of the frontal poles, referred to as the ‘Mount Fuji sign’. Surgical revision of a dural air leak resulted in rapid improvement and full clinical resolution. Early diagnosis of tension pneumocephalus and emergent surgical treatment are crucial to prevent life-threatening deterioration.

  6. Can Sensors Solve the Deterioration Problems of Public Infrastructure?

    Science.gov (United States)

    Miki, Chitoshi

    2014-11-01

    Various deteriorations are detected in public infrastructures, such as bridges, viaducts, piers and tunnels and caused fatal accidents in some cases. The possibility of the applications of health monitoring by using sensors is the issues of this lecture. The inspection and diagnosis are essential in the maintenance works which include appropriate rehabilitations and replacements. The introduction of monitoring system may improve accuracy and efficiency of inspection and diagnosis. This seems to be innovation of maintenance, old structures may change smart structures by the installation of nerve network and brain, specifically. Cost- benefit viewpoint is also important point, because of public infrastructures. The modes of deterioration are fatigue, corrosion, and delayed fracture in steel, and carbonization and alkali aggregate reaction in concrete. These are like adult disease in human bodies. The developments of Infrastructures in Japan were concentrated in the 1960th and 1970th. These ages are approaching 50 and deterioration due to aging has been progress gradually. The attacks of earthquakes are also a major issue. Actually, these infrastructures have been supporting economic and social activities in Japan and the deterioration of public infrastructure has become social problems. How to secure the same level of safety and security for all public infrastructures is the challenge we face now. The targets of monitoring are external disturbances such as traffic loads, earthquakes, winds, temperature, responses against external disturbances, and the changes of performances. In the monitoring of infrastructures, 3W1H(WHAT, WHERE, WHEN and HOW) are essential, that is what kind of data are necessary, where sensors place, when data are collected, and how to collect and process data. The required performances of sensors are accuracy, stability for long time. In the case of long term monitoring, the durability of systems needs more than five years, because the interval

  7. Can Sensors Solve the Deterioration Problems of Public Infrastructure?

    International Nuclear Information System (INIS)

    Miki, Chitoshi

    2014-01-01

    Various deteriorations are detected in public infrastructures, such as bridges, viaducts, piers and tunnels and caused fatal accidents in some cases. The possibility of the applications of health monitoring by using sensors is the issues of this lecture. The inspection and diagnosis are essential in the maintenance works which include appropriate rehabilitations and replacements. The introduction of monitoring system may improve accuracy and efficiency of inspection and diagnosis. This seems to be innovation of maintenance, old structures may change smart structures by the installation of nerve network and brain, specifically. Cost- benefit viewpoint is also important point, because of public infrastructures. The modes of deterioration are fatigue, corrosion, and delayed fracture in steel, and carbonization and alkali aggregate reaction in concrete. These are like adult disease in human bodies. The developments of Infrastructures in Japan were concentrated in the 1960th and 1970th. These ages are approaching 50 and deterioration due to aging has been progress gradually. The attacks of earthquakes are also a major issue. Actually, these infrastructures have been supporting economic and social activities in Japan and the deterioration of public infrastructure has become social problems. How to secure the same level of safety and security for all public infrastructures is the challenge we face now. The targets of monitoring are external disturbances such as traffic loads, earthquakes, winds, temperature, responses against external disturbances, and the changes of performances. In the monitoring of infrastructures, 3W1H(WHAT, WHERE, WHEN and HOW) are essential, that is what kind of data are necessary, where sensors place, when data are collected, and how to collect and process data. The required performances of sensors are accuracy, stability for long time. In the case of long term monitoring, the durability of systems needs more than five years, because the interval

  8. Properties of Concrete Mixes with Carwash Wastewater

    Directory of Open Access Journals (Sweden)

    Shahidan Shahiron

    2017-01-01

    Full Text Available The rapid growth of the car wash industry today results in the need for wastewater reclamation. Thus, this paper aims to investigate the effect of using car wash wastewater on concrete properties in terms of mechanical properties. The basic characteristics of wastewater were investigated according to USEPA (Method 150.1 & 3 00.0 while the mechanical properties of concrete with car wash wastewater were compared according to ASTM C1602 and BS EN 1008 standards. In this research, the compressive strength, modulus of elasticity and tensile strength were studied. The percentages of wastewater replaced in the concrete mix ranged from 0% up to 40%. In addition, the results also suggest that the concrete with 20% car wash wastewater achieved the highest compressive strength and modulus of elasticity compared to other compositions of wastewater. Moreover, the results also recommended that concrete mixed with car wash wastewater has better compressive strength compared to conventional concrete.

  9. Very heavy iron-punching concretes

    International Nuclear Information System (INIS)

    Dubois, F.

    1966-01-01

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

  10. STRENGTH AND DURABILITY STUDIES ON SODIUM NITRITE INHIBITOR IN ORDINARY AND HIGH PERFORMANCE CONCRETE

    OpenAIRE

    Madhavan, V.; Jeyasehar, C. Antony

    2013-01-01

    Deterioration of concrete occurs due to physical actions, chemical reactions and electro chemical reactions at steel / concrete interface causing reinforcement corrosion. Among these, reinforcement corrosion is one of the most important causes of deterioration. Reinforcement corrosion induced by chlorides is one of the most frequent causes of corrosion of steel and 40 percent of steel corrodes due to chloride attack. To delay the corrosion process many techniques such as increasing the concre...

  11. Coupled hygrothermal, electrochemical, and mechanical modelling for deterioration prediction in reinforced cementitious materials

    DEFF Research Database (Denmark)

    Michel, Alexander; Geiker, Mette Rica; Lepech, M.

    2017-01-01

    In this paper a coupled hygrothermal, electrochemical, and mechanical modelling approach for the deterioration prediction in cementitious materials is briefly outlined. Deterioration prediction is thereby based on coupled modelling of (i) chemical processes including among others transport of hea......, i.e. information, such as such as corrosion current density, damage state of concrete cover, etc., are constantly exchanged between the models....... and matter as well as phase assemblage on the nano and micro scale, (ii) corrosion of steel including electrochemical processes at the reinforcement surface, and (iii) material performance including corrosion- and load-induced damages on the meso and macro scale. The individual FEM models are fully coupled...

  12. Refractory concretes

    International Nuclear Information System (INIS)

    Holcombe, C.E. Jr.

    1979-01-01

    Novel concrete compositions comprise particles of aggregate material embedded in a cement matrix, said cement matrix produced by contacting an oxide selected from the group of Y 2 O 3 , La 2 O 3 , Nd 2 O 3 , Sm 2 O 3 , Eu 2 O 3 and Gd 2 O 3 with an aqueous solution of a salt selected from the group of NH 4 HO 3 , NH 4 Cl, YCl 3 and Mg(NO 3 ) 2 to form a fluid mixture; and allowing the fluid mixture to harden

  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. Decision analysis for deteriorating structures

    International Nuclear Information System (INIS)

    Val, Dimitri V.; Stewart, Mark G.

    2005-01-01

    Measures that improve durability of a structure usually increase its initial cost. Thus, in order to make a decision about a cost-effective solution the life-cycle cost of a structure including cost of structural failure needs to be considered. Due to uncertainties associated with structural properties, loads and environmental conditions the cost of structural failure is a random variable. The paper derives probability distributions of the cost of failure of a single structure and a group of identical structures when single or multiple failures are possible during the service life of a structure. The probability distributions are based on cumulative probabilities of failure of a single structure over its service life. It is assumed that failures occur at discrete points in time, the cost of failure set at the time of decision making remains constant for a particular design solution and the discount rate is a deterministic parameter not changing with time. The probability distributions can be employed to evaluate the expected life-cycle cost or the expected utility, which is then used in decision making. An example, which considers the selection of durability specifications for a reinforced concrete structure built on the coast, illustrates the use of the derived probability distributions

  15. Recycled concrete aggregate in portland cement concrete.

    Science.gov (United States)

    2013-01-01

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

  16. Mineralogical and chemical assessment of concrete damaged by the oxidation of sulfide-bearing aggregates: Importance of thaumasite formation on reaction mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, A. [Centre de Recherche sur les Infrastructures en Beton (CRIB), Universite Laval, 1065 ave de la Medecine, Quebec, QC, Canada G1V 0A6 (Canada); Duchesne, J., E-mail: josee.duchesne@ggl.ulaval.ca [Centre de Recherche sur les Infrastructures en Beton (CRIB), Universite Laval, 1065 ave de la Medecine, Quebec, QC, Canada G1V 0A6 (Canada); Fournier, B. [Centre de Recherche sur les Infrastructures en Beton (CRIB), Universite Laval, 1065 ave de la Medecine, Quebec, QC, Canada G1V 0A6 (Canada); Durand, B. [Institut de recherche d' Hydro-Quebec (IREQ), 1740 boul. Lionel-Boulet, Varennes, QC, Canada J3X 1S1 (Canada); Rivard, P. [Universite de Sherbrooke, Sherbrooke, QC, Canada J1K 2R1 (Canada); Shehata, M. [Ryerson University, 350 Victoria Street, Toronto, ON, Canada M5B 2K3 (Canada)

    2012-10-15

    Damages in concrete containing sulfide-bearing aggregates were recently observed in the Trois-Rivieres area (Quebec, Canada), characterized by rapid deterioration within 3 to 5 years after construction. A petrographic examination of concrete core samples was carried out using a combination of tools including: stereomicroscopic evaluation, polarized light microscopy, scanning electron microscopy, X-ray diffraction and electron microprobe analysis. The aggregate used to produce concrete was an intrusive igneous rock with different metamorphism degrees and various proportions of sulfide minerals. In the rock, sulfide minerals were often surrounded by a thin layer of carbonate minerals (siderite). Secondary reaction products observed in the damaged concrete include 'rust' mineral forms (e.g. ferric oxyhydroxides such as goethite, limonite (FeO (OH) nH{sub 2}O) and ferrihydrite), gypsum, ettringite and thaumasite. In the presence of water and oxygen, pyrrhotite oxidizes to form iron oxyhydroxides and sulphuric acid. The acid then reacts with the phases of the cement paste/aggregate and provokes the formation of sulfate minerals. Understanding both mechanisms, oxidation and internal sulfate attack, is important to be able to duplicate the damaging reaction in laboratory conditions, thus allowing the development of a performance test for evaluating the potential for deleterious expansion in concrete associated with sulfide-bearing aggregates.

  17. Mineralogical and chemical assessment of concrete damaged by the oxidation of sulfide-bearing aggregates: Importance of thaumasite formation on reaction mechanisms

    International Nuclear Information System (INIS)

    Rodrigues, A.; Duchesne, J.; Fournier, B.; Durand, B.; Rivard, P.; Shehata, M.

    2012-01-01

    Damages in concrete containing sulfide-bearing aggregates were recently observed in the Trois-Rivières area (Quebec, Canada), characterized by rapid deterioration within 3 to 5 years after construction. A petrographic examination of concrete core samples was carried out using a combination of tools including: stereomicroscopic evaluation, polarized light microscopy, scanning electron microscopy, X-ray diffraction and electron microprobe analysis. The aggregate used to produce concrete was an intrusive igneous rock with different metamorphism degrees and various proportions of sulfide minerals. In the rock, sulfide minerals were often surrounded by a thin layer of carbonate minerals (siderite). Secondary reaction products observed in the damaged concrete include “rust” mineral forms (e.g. ferric oxyhydroxides such as goethite, limonite (FeO (OH) nH 2 O) and ferrihydrite), gypsum, ettringite and thaumasite. In the presence of water and oxygen, pyrrhotite oxidizes to form iron oxyhydroxides and sulphuric acid. The acid then reacts with the phases of the cement paste/aggregate and provokes the formation of sulfate minerals. Understanding both mechanisms, oxidation and internal sulfate attack, is important to be able to duplicate the damaging reaction in laboratory conditions, thus allowing the development of a performance test for evaluating the potential for deleterious expansion in concrete associated with sulfide-bearing aggregates.

  18. The Future Concrete: Self-Compacting Concrete

    Directory of Open Access Journals (Sweden)

    Liana Iureş

    2010-01-01

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

  19. The Future Concrete: Self-Compacting Concrete

    OpenAIRE

    Iureş, Liana; Bob, Corneliu

    2010-01-01

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

  20. An international data base of nuclear concrete containment ageing

    International Nuclear Information System (INIS)

    Seni, C.; Ianko, L.

    1994-01-01

    The ageing of nuclear structures is of special interest because of the extended service life expected of these structures, and the potential impact of their deterioration on safety and reliability. Although there are databases about concrete, they address properties in general, not performance. In 1992, the IAEA, in collaboration with AECL, set out to create a new database that would fill the gap. Functional ageing, i.e. deterioration of leak-tightness, was to be included, not just structural ageing, i.e. deterioration of load-bearing capacity. This paper outlines the project of creating the database

  1. 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

  2. Using of Stone Flour from Some Mineral Rocks in Modern Concrete

    Science.gov (United States)

    Roman, Moskvin; Elena, Belyakova; Marina, Moroz

    2018-03-01

    There is shown the possibility of using mill ground rocks in SCC without deterioration of rheological properties of concrete mixtures. Obtained high-strength concrete of the new generation with high technical and economic indices and low unit costs per unit of cement strength.

  3. The thaumasite form of sulfate attack in concrete of Yongan Dam

    International Nuclear Information System (INIS)

    Hu Mingyu; Long Fumei; Tang Mingshu

    2006-01-01

    According to microanalytical investigations, it is shown that the concrete of Yongan Dam is deteriorated due to the thaumasite form of sulfate attack (TSA). Analysis results of scanning electron microscopy (SEM), Energy Disperse X-ray (EDX) and X-ray Diffraction (XRD) are supported by the analysis of the concrete composition and the geographical conditions of the dam

  4. Investigation of the internal stresses caused by delayed ettringite formation in concrete.

    Science.gov (United States)

    2008-11-01

    Delayed ettringite formation (DEF) in concrete has been identified in recent as a significant cause of deterioration in : some of the reinforced concrete infrastructure in Texas. This report is part of a research project, TxDOT project : 5218, to inv...

  5. Durability of high performance concrete in seawater

    International Nuclear Information System (INIS)

    Amjad Hussain Memon; Salihuddin Radin Sumadi; Rabitah Handan

    2000-01-01

    This paper presents a report on the effects of blended cements on the durability of high performance concrete (HPC) in seawater. In this research the effect of seawater was investigated. The specimens were initially subjected to water curing for seven days inside the laboratory at room temperature, followed by seawater curing exposed to tidal zone until testing. In this study three levels of cement replacement (0%, 30% and 70%) were used. The combined use of chemical and mineral admixtures has resulted in a new generation of concrete called HPC. The HPC has been identified as one of the most important advanced materials necessary in the effort to build a nation's infrastructure. HPC opens new opportunities in the utilization of the industrial by-products (mineral admixtures) in the construction industry. As a matter of fact permeability is considered as one of the fundamental properties governing the durability of concrete in the marine environment. Results of this investigation indicated that the oxygen permeability values for the blended cement concretes at the age of one year are reduced by a factor of about 2 as compared to OPC control mix concrete. Therefore both blended cement concretes are expected to withstand in the seawater exposed to tidal zone without serious deterioration. (Author)

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

    Science.gov (United States)

    Turick, Charles E; Berry, Christopher J

    2016-01-01

    Storage of radioactive waste in concrete structures is a means of containing wastes and related radionuclides generated from nuclear operations in many countries. Previous efforts related to microbial impacts on concrete structures that are used to contain radioactive waste showed that microbial activity can play a significant role in the process of concrete degradation and ultimately structural deterioration. This literature review examines the research in this field and is focused on specific parameters that are applicable to modeling and prediction of the fate of concrete structures used to store or dispose of radioactive waste. Rates of concrete biodegradation vary with the environmental conditions, illustrating a need to understand the bioavailability of key compounds involved in microbial activity. Specific parameters require pH and osmotic pressure to be within a certain range to allow for microbial growth as well as the availability and abundance of energy sources such as components involved in sulfur, iron and nitrogen oxidation. Carbon flow and availability are also factors to consider in predicting concrete biodegradation. The microbial contribution to degradation of the concrete structures containing radioactive waste is a constant possibility. The rate and degree of concrete biodegradation is dependent on numerous physical, chemical and biological parameters. Parameters to focus on for modeling activities and possible options for mitigation that would minimize concrete biodegradation are discussed and include key conditions that drive microbial activity on concrete surfaces. Copyright © 2015. Published by Elsevier Ltd.

  7. Performance of Microbial Concrete Developed Using Bacillus Subtilus JC3

    Science.gov (United States)

    Rao, M. V. Seshagiri; Reddy, V. Srinivasa; Sasikala, Ch.

    2017-12-01

    Concrete is vulnerable to deterioration, corrosion, and cracks, and the consequent damage and loss of strength requires immensely expensive remediation and repair. So need for special concrete that they would respond to crack formation with an autonomous self-healing action lead to research and development of microbial concrete. The microbial concrete works on the principle of calcite mineral precipitation by a specific group of alkali-resistant spore-forming bacteria related to the genus Bacillus called Bacillus subtilis JC3, this phenomenon is called biomineralization or Microbiologically Induced Calcite Crystal Precipitation. Bacillus subtilis JC3, a common soil bacterium, has inherent ability to precipitate calcite crystals continuously which enhances the strength and durability performance of concrete enormously. This microbial concrete can be called as a "Self healing Bacterial Concrete" because it can remediate its cracks by itself without any human intervention and would make the concrete more durable and sustainable. This paper discuss the incorporation of microorganism Bacillus subtilis JC3 (developed at JNTU, India) into concrete and presents the results of experimental investigations carried out to study the improved durability and sustainability characteristics of microbial concrete.

  8. Acoustic Emission Analysis of Prestressed Concrete Structures

    Science.gov (United States)

    Elfergani, H. A.; Pullin, R.; Holford, K. M.

    2011-07-01

    Corrosion is a substantial problem in numerous structures and in particular corrosion is very serious in reinforced and prestressed concrete and must, in certain applications, be given special consideration because failure may result in loss of life and high financial cost. Furthermore corrosion cannot only be considered a long term problem with many studies reporting failure of bridges and concrete pipes due to corrosion within a short period after they were constructed. The concrete pipes which transport water are examples of structures that have suffered from corrosion; for example, the pipes of The Great Man-Made River Project of Libya. Five pipe failures due to corrosion have occurred since their installation. The main reason for the damage is corrosion of prestressed wires in the pipes due to the attack of chloride ions from the surrounding soil. Detection of the corrosion in initial stages has been very important to avoid other failures and the interruption of water flow. Even though most non-destructive methods which are used in the project are able to detect wire breaks, they cannot detect the presence of corrosion. Hence in areas where no excavation has been completed, areas of serious damage can go undetected. Therefore, the major problem which faces engineers is to find the best way to detect the corrosion and prevent the pipes from deteriorating. This paper reports on the use of the Acoustic Emission (AE) technique to detect the early stages of corrosion prior to deterioration of concrete structures.

  9. Acoustic Emission Analysis of Prestressed Concrete Structures

    International Nuclear Information System (INIS)

    Elfergani, H A; Pullin, R; Holford, K M

    2011-01-01

    Corrosion is a substantial problem in numerous structures and in particular corrosion is very serious in reinforced and prestressed concrete and must, in certain applications, be given special consideration because failure may result in loss of life and high financial cost. Furthermore corrosion cannot only be considered a long term problem with many studies reporting failure of bridges and concrete pipes due to corrosion within a short period after they were constructed. The concrete pipes which transport water are examples of structures that have suffered from corrosion; for example, the pipes of The Great Man-Made River Project of Libya. Five pipe failures due to corrosion have occurred since their installation. The main reason for the damage is corrosion of prestressed wires in the pipes due to the attack of chloride ions from the surrounding soil. Detection of the corrosion in initial stages has been very important to avoid other failures and the interruption of water flow. Even though most non-destructive methods which are used in the project are able to detect wire breaks, they cannot detect the presence of corrosion. Hence in areas where no excavation has been completed, areas of serious damage can go undetected. Therefore, the major problem which faces engineers is to find the best way to detect the corrosion and prevent the pipes from deteriorating. This paper reports on the use of the Acoustic Emission (AE) technique to detect the early stages of corrosion prior to deterioration of concrete structures.

  10. Concrete Memories

    DEFF Research Database (Denmark)

    Wiegand, Frauke Katharina

    2015-01-01

    This article traces the presence of Atlantikwall bunkers in amateur holiday snapshots and discusses the ambiguous role of the bunker site in visual cultural memory. Departing from my family’s private photo collection from twenty years of vacationing at the Danish West coast, the different mundane...... and poetic appropriations and inscriptions of the bunker site are depicted. Ranging between overlooked side presences and an overwhelming visibility, the concrete remains of fascist war architecture are involved in and motivate different sensuous experiences and mnemonic appropriations. The article meets...... the bunkers’ changing visuality and the cultural topography they both actively transform and are being transformed by through juxtaposing different acts and objects of memory over time and in different visual articulations....

  11. Phase 2 microwave concrete decontamination results

    International Nuclear Information System (INIS)

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

    1995-01-01

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

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

    Directory of Open Access Journals (Sweden)

    P. T. C. Mendes

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

  13. Civil engineering: EDF needs for concrete modelling

    International Nuclear Information System (INIS)

    Didry, O.; Gerard, B.; Bui, D.

    1997-01-01

    Concrete structures which are encountered at EDF, like all civil engineering structures, age. In order to adapt the maintenance conditions of these structures, particularly to extend their service life, and also to prepare constructions of future structures, tools for predicting the behaviour of these structures in their environment should be available. For EDF the technical risks are high and consequently very appropriate R and D actions are required. In this context the Direction des Etudes et Recherches (DER) has developed a methodology for analysing concrete structure behaviour modelling. This approach has several aims: - making a distinction between the problems which refer to the existing models and those which require R and D; - displaying disciplinary links between different problems encountered on EDF structures (non-linear mechanical, chemical - hydraulic - mechanical coupling, etc); - listing of the existing tools and positioning the DER 'Aster' finite element code among them. This document is a state of the art of scientific knowledge intended to shed light on the fields in which one should be involved when there is, on one part a strong requirement on the side of structure operators, and on the other one, the present tools do not allow this requirement to be satisfactorily met. The analysis has been done on 12 scientific subjects: 1) Hydration of concrete at early ages: exothermicity, hardening, autogenous shrinkage; 2) Drying and drying shrinkage; 3) Alkali-silica reaction and bulky stage formation; 4) Long term deterioration by leaching; 5) Ionic diffusion and associated attacks: the chlorides case; 6) Permeability / tightness of concrete; 7) Concretes -nonlinear behaviour and cracking (I): contribution of the plasticity models; 8) Concretes - nonlinear behaviour and cracking (II): contribution of the damage models; 9) Concretes - nonlinear behaviour and cracking (III): the contribution of the probabilistic analysis model; 10) Delayed behaviour of

  14. Durability of concrete materials in high-magnesium brine

    International Nuclear Information System (INIS)

    Wakeley, L.D.; Poole, T.S.; Burkes, J.P.

    1994-03-01

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

  15. Bacteria-based self-healing concrete : Introduction

    NARCIS (Netherlands)

    Mors, R.M.; Jonkers, H.M.

    2012-01-01

    Concrete in most structures is designed to crack in order to let embedded steel reinforcement take over tensile stresses. Crack formation is also a typical phenomenon related to durability. Percolation of cracks may lead to leakage problems or ingress of deleterious materials, causing deterioration

  16. Damage induced by continued corrosion in concrete repair systems

    NARCIS (Netherlands)

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

    2014-01-01

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

  17. On Reliability Based Optimal Design of Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In recent years important progress has been made in assessment of the lifetime behaviour of concrete bridges. Due to the large uncertainties related to the loading and the deterioration of such bridges, an assessment based on stochastic modelling of the significant parameters seems to be only...

  18. Assessment of the Reliability Profiles for Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper calculation of reliability profiles is discussed. ULS as well as SLS limit states are formulated. Corrosion due to chloride penetration is the considered deterioration mechanism. Three models for corrosion are formulated. A definition of service lifetime for concrete bridges...

  19. 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.

  20. Finite element analysis of degraded concrete structures - Workshop proceedings

    International Nuclear Information System (INIS)

    1999-09-01

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

  1. Unbonded portland cement concrete overlay/pavement monitoring with integrated grating and scattering optical fiber sensors.

    Science.gov (United States)

    2014-06-01

    This report summarizes the findings and results from a laboratory and field study on the strain distribution : and crack development in 3 thick concrete panels cast on top of existing concrete pavements as a rapid : rehabilitation strategy for roa...

  2. Neutron imaging of water penetration into cracked steel reinforced concrete

    International Nuclear Information System (INIS)

    Zhang, P.; Wittmann, F.H.; Zhao, T.; Lehmann, E.H.

    2010-01-01

    Service life and durability of reinforced concrete structures have become a crucial issue because of the economical and ecological implications. Service life of reinforced concrete structures is often limited by penetration of water and chemical compounds dissolved in water into the porous cement-based material. By now it is well-known that cracks in reinforced concrete are preferential paths for ingress of aggressive substances. Neutron radiography was successfully applied to study the process of water penetration into cracked steel reinforced concrete. In addition, the effectiveness of integral water repellent concrete to prevent ingress of water and salt solutions was investigated. Results are described in detail in this contribution. It will be shown that neutron radiography is a powerful method to visualize the process of water penetration into cracked and uncracked cement-based materials. On the basis of the obtained experimental data, it is possible to quantify the time-dependent water distributions in concrete with high accuracy and spatial resolution. It is of particular interest that penetration of water and salt solutions into damaged interfaces between concrete and steel can be visualized by means of neutron radiography. Deteriorating processes in cracked reinforced concrete structures can be studied in a completely new way. This advanced technology will help and find adequate ways to improve durability and service life of reinforced concrete structures. This will mean at the same time an essential contribution to improved sustainability.

  3. Deterioration and cost information for bridge management.

    Science.gov (United States)

    2012-05-01

    This study applies contract bid tabulations and elementlevel condition records to develop elementlevel actions, : costs for actions, transition probabilities for models of deterioration of bridge elements, and transition probabilities : for imp...

  4. The deterioration of intermediate moisture foods

    Science.gov (United States)

    Labruza, T. P.

    1971-01-01

    Deteriorative reactions are low and food quality high if intermediate moisture content of a food is held at a water activity of 0.6 to 0.75. Information is of interest to food processing and packaging industry.

  5. Deteriorating Inventory Model for Chilled Food

    OpenAIRE

    Yang, Ming-Feng; Tseng, Wei-Chung

    2015-01-01

    With many aspects that affect inventory policy, product perishability is a critical aspect of inventory policy. Most goods will deteriorate during storage and their original value will decline or be lost. Therefore, deterioration should be taken into account in inventory practice. Chilled food products are very common consumer goods that are, in fact, perishable. If the chilled food quality declines over time customers are less likely to buy it. The value the chilled food retains is, however,...

  6. Early warnings of heart rate deterioration

    OpenAIRE

    Almeida, Vânia G.; Nabney, Ian T.

    2016-01-01

    Hospitals can experience difficulty in detecting and responding to early signs of patient deterioration leading to late intensive care referrals, excess mortality and morbidity, and increased hospital costs. Our study aims to explore potential indicators of physiological deterioration by the analysis of vital-signs. The dataset used comprises heart rate (HR) measurements from MIMIC II waveform database, taken from six patients admitted to the Intensive Care Unit (ICU) and diagnosed with sever...

  7. Rule based deterioration identification and management system

    International Nuclear Information System (INIS)

    Kataoka, S.; Pavinich, W.; Lapides, M.

    1993-01-01

    Under the sponsorship of IHI and EPRI, a rule-based screening system has been developed that can be used by utility engineers to determine which deterioration mechanisms are acting on specific LWR components, and to evaluate the efficacy of an age-related deterioration management program. The screening system was developed using the rule-based shell, NEXPERT, which provides traceability to the data sources used in the logic development. The system addresses all the deterioration mechanisms of specific metals encountered in either BWRs or PWRs. Deterioration mechanisms are listed with reasons why they may occur during the design life of LWRs, considering the plant environment, manufacturing process, service history, material chemical composition, etc. of components in a specific location of a LWR. To eliminate the evaluation of inactive deterioration quickly, a tier structure is applied to the rules. The reasons why deterioration will occur are extracted automatically by backward chaining. To reduce the amount of user input, plant environmental data are stored in files as default environmental data. (author)

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

    Science.gov (United States)

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

    2014-01-01

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

  9. High performance concretes applied to hazardous wastes disposal; Concretos de alto desempenho aplicados a repositorios de rejeitos solidos perigosos

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Claudio A. Rigo da; Vasconcelos, Wander L. [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Dept. de Engenharia Materiais e Construcao; Reis, Rubens J. P. [FUMEC Fundacao Mineira de Educacao e Cultura, Belo Horizonte, MG (Brazil). Faculdade de Engenharia e Arquitetura; Lameiras, Fernando S. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil)

    2000-07-01

    Materials used as engineering barriers for solid waste disposal requires structures which avoid diffusion of dangerous elements to the environment, as well as the incorporation of external agents in the disposal. Concretes represent a good choice for making engineering barriers due to their low cost and ease of fabrication. In order to promote a low deterioration rate it is necessary to decrease crack formation and flow of water and ions through the concrete matrix, which may be accomplished using concretes of low porosity and high compression strengths. In this work, a concrete C35 (characteristic compression strength between 35 and 39 MPa, NBR 8953 standard) was submitted to accelerated deterioration tests by sulfates, carbonates and gamma radiation. We observed that the concrete kept its mechanical properties after the deterioration tests carried out. A microstructural evaluation revealed low porosity and strong cohesion of the components. (author)

  10. Fibre Concrete 2017

    Science.gov (United States)

    2017-09-01

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

  11. Concrete aggregate durability study.

    Science.gov (United States)

    2009-06-01

    There are many factors that affect the durability of Portland cement concrete (PCC), including the mix design and the : materials used, the quality of construction, and the environment. Durability is not an intrinsic property of the concrete, but : i...

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

    International Nuclear Information System (INIS)

    Hamilton, M.A.; Rogers, R.D.; Zolynski, M.; Veeh, R.

    1996-01-01

    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

  13. Reinforced sulphur concrete

    NARCIS (Netherlands)

    2014-01-01

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

  14. 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.

  15. D-cracking field performance of portland cement concrete pavements containing limestone in Kansas : phase 1 report : technical summary.

    Science.gov (United States)

    2012-05-01

    Introduction: Premature deterioration of concrete pavement due to D-cracking has been a problem in Kansas since the 1930s. Limestone is the major source of coarse aggregate in eastern Kansas where the majority of the concrete pavements are constructe...

  16. Full surface inspection methods regarding reinforcement corrosion of concrete structures

    International Nuclear Information System (INIS)

    Reichling, K.; Raupach, M.; Broomfield, J.; Gulikers, J.; L'Hostis, Valerie

    2013-01-01

    For reinforced concrete structures a localisation of all significant critical areas can only be done by a full surface inspection. The economic advantages are obvious: uncritical areas have not to be repaired expensively.The first step of the assessment should always be a visual inspection. The range of deterioration causes can be limited and the degree of deterioration may be estimated roughly. The inspection program can be adjusted to the requirements. By means of a full surface potential mapping areas with a high risk for chloride induced reinforcement corrosion can be localised, although no deteriorations are visually detectable at the concrete surface. In combination with concrete cover depth and resistivity measurements areas with corrosion promoting exposure conditions can be localised even if the reinforcement is not yet de-passivated. The following publication gives an overview about the essential full surface investigation methods to localise critical areas regarding corrosion of steel in concrete. The selection of methods is based on the inspection procedure given in reference 2. (authors)

  17. Modified pavement cement concrete

    Science.gov (United States)

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

    2018-03-01

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

  18. Material properties characterization - concrete

    International Nuclear Information System (INIS)

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

    1978-01-01

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

  19. Behavior of corroded bonded partially prestressed concrete beams

    Directory of Open Access Journals (Sweden)

    Mohamed Moawad

    2018-04-01

    Full Text Available Prestressed concrete is widely used in the construction industry in buildings. And corrosion of reinforcing steel is one of the most important and prevalent mechanisms of deterioration for concrete structures. Consequently the capacity of post-tension elements decreased after exposure to corrosion. This study presents results of the experimental investigation of the performance and the behavior of partially prestressed beams, with 40 and 80 MPa compressive strength exposed to corrosion. The experimental program of this study consisted of six partially prestressed beams with overall dimensions equal to 150 × 400 × 4500 mm. The variables were considered in terms of concrete compressive strength, and corrosion location effect. The mode of failure, and strain of steel reinforcement, cracking, yield, ultimate load and the corresponding deflection of each beam, and crack width and distribution were recorded. The results showed that the partially prestressed beam with 80 MPa compressive strength has higher resistance to corrosion exposure than that of partially prestressed concrete beam with 40 MPa compressive strength. Not big difference in deterioration against fully/partially corrosion exposure found between partially prestressed beams at the same compressive strength. The most of deterioration incident in partially prestressed beam acts on non prestressed steel reinforcement. Because the bonded tendons are less likely to corrode, cement grout and duct act as a barrier to moisture and chloride penetration, especially plastic duct without splices and connections. The theoretical analysis based on strain compatibility and force equilibrium gave a good prediction of the deformational behavior for high/normal partially prestressed beams. Keywords: Beam, Corrosion, Deterioration, Partially prestressed, High strength concrete

  20. 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...

  1. 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...

  2. 40 CFR 94.218 - Deterioration factor determination.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Deterioration factor determination. 94... Deterioration factor determination. Manufacturers shall determine exhaust emission deterioration factors using good engineering judgement according to the provisions of this section. Every deterioration factor must...

  3. CONCRETE BASED ON MODIFIED DISPERSE CEMENT SYSTEM

    Directory of Open Access Journals (Sweden)

    D. V. Rudenko

    2016-08-01

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

  4. Inelastic analysis of prestressed concrete secondary containments

    International Nuclear Information System (INIS)

    Murray, D.W.; Chitnuyanondh, L.; Wong, C.; Rijub-Agha, K.Y.

    1978-07-01

    An elastic-plastic constitutive model for the simulation of stress-strain response of concrete under any biaxial combination of compressive and/or tensile stresses is developed. An effective tensile stress-strain curve is obtained indirectly from experimental results of a test on a large scale prestressed concrete wall segment. These concrete properties are then utilized in predicting the response of a second test and the results compared with the experiment. Modificications to the BOSOR5 program, in order to incorporate the new constitutive relation into it, are described. Techniques of modelling structures in order to perform inelastic analysis of thin shell axisymmetric prestressed concrete secondary containments are investigated. The results of inelastic BOSOR5 analyses of two different models of the University of Alberta Test Structure are presented. The predicted deterioration of the structure and the limit states associated with its behaviour are determined and discussed. It is concluded that the technique is a practical one which can be used for the inelastic analysis of Gentilly-type containment structures. (author)

  5. Simulation of 20-year deterioration of acrylic IOLs using severe accelerated deterioration tests.

    Science.gov (United States)

    Kawai, Kenji; Hayakawa, Kenji; Suzuki, Takahiro

    2012-09-20

    To investigate IOL deterioration by conducting severe accelerated deterioration testing of acrylic IOLs. Department of Ophthalmology, Tokai University School of Medicine Methods: Severe accelerated deterioration tests performed on 7 types of acrylic IOLs simulated 20 years of deterioration. IOLs were placed in a screw tube bottle containing ultra-pure water and kept in an oven (100°C) for 115 days. Deterioration was determined based the outer appearance of the IOL in water and under air-dried conditions using an optical microscope. For accelerated deterioration of polymeric material, the elapse of 115 days was considered to be equivalent to 20 years based on the Arrhenius equation. All of the IOLs in the hydrophobic acrylic group except for AU6 showed glistening-like opacity. The entire optical sections of MA60BM and SA60AT became yellowish white in color. Hydrophilic acrylic IOL HP60M showed no opacity at any of the time points examined. Our data based on accelerated testing showed differences in water content to play a major role in transparency. There were differences in opacity among manufacturers. The method we have used for determining the relative time of IOL deterioration might not represent the exact clinical setting, but the appearance of the materials would presumably be very similar to that seen in patients.

  6. Stress analysis of heated concrete using finite elements

    International Nuclear Information System (INIS)

    Majumdar, P.; Gupta, A.; Marchertas, A.

    1994-01-01

    Described is a finite element analysis of concrete, which is subjected to rapid heating. Using thermal mass transport calculation, the moisture content, temperature and pore pressure distribution over space and time is obtained first. From these effects, stress at various points of the concrete are computed using the finite element method. Contribution to the stress formulation comes from three components, namely the thermal expansion, pore pressure, and the shrinkage of concrete due to moisture loss (from dehydration). The material properties of concrete are assumed to be homogeneous, elastic, and cracking is not taken into consideration. (orig.)

  7. Evaluation of resistivity meters for concrete quality assurance.

    Science.gov (United States)

    2015-06-01

    This research evaluated a series of MoDOT concrete mixtures to verify existing relationships between surface resistivity (SR), rapid : chloride permeability (RCP), chloride ion diffusion, and the AASHTO penetrability classes. The research also perfor...

  8. Periodic review inventory policy for non-instantaneous deteriorating items with time dependent deterioration rate

    Directory of Open Access Journals (Sweden)

    Anwesha Samanta

    2015-09-01

    Full Text Available The paper studies a periodic review inventory model with no shortages and different demand rates during pre- and post- deterioration periods . Deterioration of units start after a fixed time interval, and the deterioration rate is time dependent. The model determines the optimal reorder interval and the optimal order quantity so as to minimize the total cost per unit length of an inventory cycle. An extension of the model to include price discount has been further considered. Numerical examples are presented to illustrate the model and a sensitivity analysis is also reported.

  9. The effects of atmospheric multipollutants on modern concrete

    Energy Technology Data Exchange (ETDEWEB)

    Marinoni, N.; Birelli, M.P.; Rostagno, C.; Pavese, A. [University of Milan, Milan (Italy)

    2003-10-01

    Concrete samples were collected from the indoor walls of a tunnel in Milan (Italy), erected at the beginning of the 20th century for railway subway. Since the second half of the 20th century, during the construction of Stazione Centrale (Central Railway Station) of Milan, the tunnel has been turned into an automobile and railway crossing, thus increasing the deposition of aggressive pollutants on building materials. Weathering layers (commonly known as black crusts) caused by deposition of atmospheric pollutants on concrete surfaces were analysed in order to investigate the main mechanisms responsible for deterioration. A mineralogical and physical-chemical characterisation of the concrete and black crusts was performed by optical microscopy, atomic absorption spectroscopy, X-ray powder diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and differential scanning calorimetry. The results attest that the main deterioration phenomenon affecting concrete is the sulphation process by dry deposition, leading to secondary salt crystallisation (gypsum formation) on the external surface of the samples. Moreover, concrete samples show widespread micro- and macro-cracking, high porosity, and corrosion phenomena at the aggregate binder interface (AAR). Airborne particulate matter produced by fuel (oil-derived and coal) combustion was found embedded in the gypsum matrix of black crusts, suggesting its catalytic role in sulphation process.

  10. Concrete laying laboratory

    International Nuclear Information System (INIS)

    Bastlova, K.

    1986-01-01

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

  11. Special protective concretes

    International Nuclear Information System (INIS)

    Bouniol, P.

    2001-01-01

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

  12. Engineering Performance of High Strength Concrete Containing Steel Fibre Reinforcement

    Directory of Open Access Journals (Sweden)

    Md Azree Othuman Mydin

    2013-09-01

    Full Text Available The development and utilization of the high strength concrete in the construction industry have been increasing rapidly. Fiber reinforced concrete is introduced to overcome the weakness of the conventional concrete because concrete normally can crack under a low tensile force and it is known to be brittle. Steel fibre is proved to be the popular and best combination in the high strength concrete to result the best in the mechanical and durability properties of high strength concrete with consideration of curing time, steel fibre geometry, concrete grade and else more. The incorporation of steel fibre in the mortar mixture is known as steel fibre reinforced concrete have the potential to produce improvement in the workability, strength, ductility and the deformation of high strength concrete. Besides that, steel fibre also increases the tensile strength of concrete and improves the mechanical properties of the steel fibre reinforced concrete. The range for any high strength concrete is between 60MPa-100MPa. Steel fibre reinforced concrete which contains straight fibres has poorer physical properties than that containing hooked end stainless steel fibre due to the length and the hooked steel fibre provide a better effective aspects ratio. Normally, steel fibre tensile strength is in the range of 1100MPa-1700MPa. Addition of less steel fibre volumes in the range of 0.5% to 1.0% can produce better increase in the flexural fatigue strength. The strength can be increased with addition of steel fibre up to certain percentage. This paper will review and present some basic properties of steel fibre reinforced concrete such as mechanical, workability and durability properties.

  13. Proposal for the Evaluation of Eco-Efficient Concrete

    Directory of Open Access Journals (Sweden)

    Taehyoung Kim

    2016-07-01

    Full Text Available The importance of environmental consequences due to diverse substances that are emitted during the production of concrete is recognized, but environmental performance tends to be evaluated separately from the economic performance and durability performance of concrete. In order to evaluate concrete from the perspective of sustainable development, evaluation technologies are required for comprehensive assessment of environmental performance, economic performance, and durability performance based on a concept of sustainable development called the triple bottom line (TBL. Herein, an assessment method for concrete eco-efficiency is developed as a technique to ensure the manufacture of highly durable and eco-friendly concrete, while minimizing both the load on the ecological environment and manufacturing costs. The assessment method is based on environmental impact, manufacturing costs, and the service life of concrete. According to our findings, eco-efficiency increased as the compressive strength of concrete increased from 21 MPa to 40 MPa. The eco-efficiency of 40 MPa concrete was about 50% higher than the eco-efficiency of 24 MPa concrete. Thus eco-efficiency is found to increase with an increasing compressive strength of concrete because the rate of increase in the service life of concrete is larger than the rate of increase in the costs. In addition, eco-efficiency (KRW/year was shown to increase for all concrete strengths as mixing rates of admixtures (Ground Granulated Blast furnace Slag increased to 30% during concrete mix design. However, when the mixing rate of admixtures increased to 40% and 60%, the eco-efficiency dropped due to rapid reduction in the service life values of concrete to 74 (year/m3 and 44 (year/m3, respectively.

  14. Monitoring Corrosion of Steel Bars in Reinforced Concrete Structures

    Science.gov (United States)

    Verma, Sanjeev Kumar; Bhadauria, Sudhir Singh; Akhtar, Saleem

    2014-01-01

    Corrosion of steel bars embedded in reinforced concrete (RC) structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for evaluating the corrosion state of RC structures, especially hal-cell potential (HCP) method. This paper also presents few techniques to protect concrete from corrosion. PMID:24558346

  15. Monitoring corrosion of steel bars in reinforced concrete structures.

    Science.gov (United States)

    Verma, Sanjeev Kumar; Bhadauria, Sudhir Singh; Akhtar, Saleem

    2014-01-01

    Corrosion of steel bars embedded in reinforced concrete (RC) structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for evaluating the corrosion state of RC structures, especially hal-cell potential (HCP) method. This paper also presents few techniques to protect concrete from corrosion.

  16. Monitoring Corrosion of Steel Bars in Reinforced Concrete Structures

    Directory of Open Access Journals (Sweden)

    Sanjeev Kumar Verma

    2014-01-01

    Full Text Available Corrosion of steel bars embedded in reinforced concrete (RC structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for evaluating the corrosion state of RC structures, especially hal-cell potential (HCP method. This paper also presents few techniques to protect concrete from corrosion.

  17. assessment of Seawater Intrusion in Concrete by Measuring Chlorine Concentration

    International Nuclear Information System (INIS)

    Abdel-Monem, A.M.; Kansouh, W.A.; Osman, A.M.; Bashter, I.I.

    2011-01-01

    The object of this work is to measure water intrusion in concrete using a new methodology based on neutron activation technique. The applied method depends on measuring the activated gamma energy lines emitted from 38 Cl using a gamma spectrometer with Ge(Li) and HPGe detectors. Concrete samples with different percentages of silica fume (SF), up to 20 % submerged in seawater for different period of time were used to perform the investigation. Samples of concrete taken from different positions along the direction of water intrusion in concrete block were irradiated by thermal neutrons using the irradiation cell of 252 Cf neutron source and one of the vertical channels of search reactor at Delft University. The measured 38 Cl concentrations of the irradiated samples were used to plot groups of water profiles distribution in concrete samples with different SF % and submerged in seawater for different periods. These profiles were compared with the others which use here measured by neutron back emitted method where a satisfactory agreement was observed between the two. Further, the displayed measured results; show that the diffusivity for all water contents decreases with increasing the silica fume percentage up to 15 %. However, for concrete samples with silica fume 20 % the observed phenomenon is reversed due to the deterioration of concrete physical and mechanical properties

  18. Quality Control of Concrete Structure For APR1400 Construction

    International Nuclear Information System (INIS)

    Seo, Inseop; Song, Changhak; Kim, Duill

    2012-01-01

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

  19. Qualifying concrete for a low-level waste repository

    International Nuclear Information System (INIS)

    Philipose, K.E.

    1990-06-01

    A waste repository for the belowground disposal of low-level radioactive waste, labelled IRUS (Intrusion Resistant Underground Structure), is planned at Chalk River Nuclear Laboratories. It relies greatly on the durability of concrete for a minimum of 500 years of service life. A research program based on laboratory testing to design a durable concrete and predict its useful engineered service life is in progress. Durability of concrete depends on its resistance of deterioration from both internal and external causes. Since the rate of degradation depends to a major extent on the rate of ingress of aggressive ions into concrete, laboratory testing is in progress to establish the diffusion rates of ions, especially chlorides, sulphate and carbonate ions. A total of 1000 concrete specimens and 500 paste specimens are being exposed at 22 and 45 degrees C to twenty-five different combinations of corrosive agents, including CO 2 . Procedures to measure the ionic profile and to determine the factors controlling diffusion of ions in the various concretes have been developed. The paper presents the initial results from the research program and the longevity predictions to qualify concretes for the IRUS waste repository, based on twelve months of diffusion testing on laboratory specimens

  20. Review Of Concrete Biodeterioration In Relation To Buried Nuclear Waste

    International Nuclear Information System (INIS)

    Turick, C.

    2012-01-01

    Long-term storage of low level radioactive material in below ground concrete disposal units (DUs) (Saltstone Disposal Facility) is a means of depositing wastes generated from nuclear operations of the U.S. Department of Energy. Based on the currently modeled degradation mechanisms, possible microbial induced effects on the structural integrity of buried low level wastes must be addressed. Previous international efforts related to microbial impacts on concrete structures that house low level radioactive waste showed that microbial activity can play a significant role in the process of concrete degradation and ultimately structural deterioration. This literature review examines the recent research in this field and is focused on specific parameters that are applicable to modeling and prediction of the fate of concrete vaults housing stored wastes and the wastes themselves. Rates of concrete biodegradation vary with the environmental conditions, illustrating a need to understand the bioavailability of key compounds involved in microbial activity. Specific parameters require pH and osmotic pressure to be within a certain range to allow for microbial growth as well as the availability and abundance of energy sources like components involved in sulfur, iron and nitrogen oxidation. Carbon flow and availability are also factors to consider in predicting concrete biodegradation. The results of this review suggest that microbial activity in Saltstone, (grouted low level radioactive waste) is unlikely due to very high pH and osmotic pressure. Biodegradation of the concrete vaults housing the radioactive waste however, is a possibility. The rate and degree of concrete biodegradation is dependent on numerous physical, chemical and biological parameters. Results from this review point to parameters to focus on for modeling activities and also, possible options for mitigation that would minimize concrete biodegradation. In addition, key chemical components that drive microbial

  1. Review of Concrete Biodeterioration in Relation to Buried Nuclear Waste

    Energy Technology Data Exchange (ETDEWEB)

    Turick, C; Berry, C.

    2012-10-15

    Long-term storage of low level radioactive material in below ground concrete disposal units (DUs) (Saltstone Disposal Facility) is a means of depositing wastes generated from nuclear operations of the U.S. Department of Energy. Based on the currently modeled degradation mechanisms, possible microbial induced effects on the structural integrity of buried low level wastes must be addressed. Previous international efforts related to microbial impacts on concrete structures that house low level radioactive waste showed that microbial activity can play a significant role in the process of concrete degradation and ultimately structural deterioration. This literature review examines the recent research in this field and is focused on specific parameters that are applicable to modeling and prediction of the fate of concrete vaults housing stored wastes and the wastes themselves. Rates of concrete biodegradation vary with the environmental conditions, illustrating a need to understand the bioavailability of key compounds involved in microbial activity. Specific parameters require pH and osmotic pressure to be within a certain range to allow for microbial growth as well as the availability and abundance of energy sources like components involved in sulfur, iron and nitrogen oxidation. Carbon flow and availability are also factors to consider in predicting concrete biodegradation. The results of this review suggest that microbial activity in Saltstone, (grouted low level radioactive waste) is unlikely due to very high pH and osmotic pressure. Biodegradation of the concrete vaults housing the radioactive waste however, is a possibility. The rate and degree of concrete biodegradation is dependent on numerous physical, chemical and biological parameters. Results from this review point to parameters to focus on for modeling activities and also, possible options for mitigation that would minimize concrete biodegradation. In addition, key chemical components that drive microbial

  2. Concrete decontamination by Electro-Hydraulic Scabbling (EHS). Topical report

    International Nuclear Information System (INIS)

    1996-01-01

    Electro-Hydraulic Scabbling (EHS) technology and equipment for decontaminating concrete structures from radionuclides, organic substances, and hazardous metals is being developed by Textron Systems Division (TSD). This wet scabbling technique involves the generation of powerful shock waves and intense cavitation by a strong pulsed electric discharge in a water layer at the concrete surface. The high pressure impulse results in stresses which crack and peel off a concrete layer of a controllable thickness. Scabbling produces contaminated debris of relatively small volume which can be easily removed, leaving clean bulk concrete. This new technology is being developed under Contract No. DE-AC21-93MC30164. The project objective is to develop and demonstrate a cost-efficient, rapid, controllable process to remove the surface layer of contaminated concrete while generating minimal secondary waste. The primary target of this program is uranium-contaminated concrete floors which constitute a substantial part of the contaminated area at DOE weapon facilities

  3. 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.

  4. Gas and water permeability tests of 25 year old concrete from the NPD Nuclear Generating Station

    International Nuclear Information System (INIS)

    Mills, R.H.

    1990-05-01

    Permeability tests on cores recovered from concrete which had been in service for 25 years in the Nuclear Power Demonstration (NPD) reactor showed rates of mass transfer of gas and water which were greater than young fresh concrete of the same proportions and that reported in previous AECB reports. This transparency of the concrete was also 2 orders of magnitude greater than that of comparable concrete which had been stored in the laboratory atmosphere for 19 years. Analysis of the effluent in water permeability tests revealed the presence of unusual amounts of soluble materials, mainly Na and K but little Ca, in the reactor concrete. This suggested service-related deterioration of the concrete rather than the release of soluble Ca by continuing hydration of cement

  5. Self-sensing of carbon nanofiber concrete columns subjected to reversed cyclic loading

    Science.gov (United States)

    Howser, R. N.; Dhonde, H. B.; Mo, Y. L.

    2011-08-01

    Civil infrastructures are generally a country's most expensive investment, and concrete is the most widely used material in the construction of civil infrastructures. During a structure's service life, concrete ages and deteriorates, leading to substantial loss of structural integrity and potentially resulting in catastrophic disasters such as highway bridge collapses. A solution for preventing such occurrences is the use of structural health monitoring (SHM) technology for concrete structures containing carbon nanofibers (CNF). CNF concrete has many structural benefits. CNF restricts the growth of nanocracks in addition to yielding higher strength and ductility. Additionally, test results indicate a relationship between electrical resistance and concrete strain, which can be well utilized for SHM. A series of reinforced concrete (RC) columns were built and tested under a reversed cyclic loading using CNF as a SHM device. The SHM device detected and assessed the level of damage in the RC columns, providing a real-time health monitoring system for the structure's overall integrity.

  6. Comminution and sizing processes of concrete block waste as recycled aggregates.

    Science.gov (United States)

    Gomes, P C C; Ulsen, C; Pereira, F A; Quattrone, M; Angulo, S C

    2015-11-01

    Due to the environmental impact of construction and demolition waste (CDW), recycling is mandatory. It is also important that recycled concrete aggregates (RCA) are used in concrete to meet market demands. In the literature, the influence of RCAs on concrete has been investigated, but very limited studies have been conducted on how the origin of concrete waste and comminution processes influence RCA characteristics. This paper aims to investigate the influence of three different comminution and sizing processes (simple screening, crushing and grinding) on the composition, shape and porosity characteristics of RCA obtained from concrete block waste. Crushing and grinding implies a reduction of RCA porosity. However, due to the presence of coarse quartz rounded river pebbles in the original concrete block mixtures, the shape characteristics deteriorated. A large amount of powder (<0.15 mm) without detectable anhydrous cement was also generated. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. A three-dimensional rupture analysis of steel liners anchored to concrete pressure and containment vessels

    International Nuclear Information System (INIS)

    Bangash, Y.

    1987-01-01

    Steel liners or plates are anchored to concrete pressure and containment vessels for nuclear and offshore facilities. Due to extreme loading conditions a liner may buckle due to the pull-out or shearing of anchors from the base metal and concrete. Under certain conditions attributed to loadings, liner metal deterioration and cracking of concrete behind the liner, the liner may fail by rupture. This paper presents a three-dimensional analysis of steel-concrete elements, using finite elements analysis in which a provision is made for liner instability, anchor strength and stiffness, concrete cracking and finally liner rupture. The analysis is tested first on an octagonal slab with and without an anchored steel liner. It is then extended to concrete pressure and containment vessels. The analytical results obtained are compared well with those available from the experimental tests and other sources. (author)

  8. Self-sensing of carbon nanofiber concrete columns subjected to reversed cyclic loading

    International Nuclear Information System (INIS)

    Howser, R N; Dhonde, H B; Mo, Y L

    2011-01-01

    Civil infrastructures are generally a country's most expensive investment, and concrete is the most widely used material in the construction of civil infrastructures. During a structure's service life, concrete ages and deteriorates, leading to substantial loss of structural integrity and potentially resulting in catastrophic disasters such as highway bridge collapses. A solution for preventing such occurrences is the use of structural health monitoring (SHM) technology for concrete structures containing carbon nanofibers (CNF). CNF concrete has many structural benefits. CNF restricts the growth of nanocracks in addition to yielding higher strength and ductility. Additionally, test results indicate a relationship between electrical resistance and concrete strain, which can be well utilized for SHM. A series of reinforced concrete (RC) columns were built and tested under a reversed cyclic loading using CNF as a SHM device. The SHM device detected and assessed the level of damage in the RC columns, providing a real-time health monitoring system for the structure's overall integrity

  9. Tardily accelerated neurologic deterioration in two-step thallium intoxication.

    Science.gov (United States)

    Kuroda, Hiroshi; Mukai, Yoshiyuki; Nishiyama, Shuhei; Takeshita, Takayuki; Tateyama, Maki; Takeda, Atsushi; Aoki, Masashi

    2016-12-01

    Thallium intoxication was reported in cases with accidental ingestion, suicide attempt, and criminal adulteration. Reported cases were mostly one-time ingestion, therefore, the clinical course of divisional ingestion has not been fully known. Here, we report a case with two-step thallium intoxication manifesting as tardily accelerated neurologic deterioration. A 16-year-old adolescent was cryptically poisoned with thallium sulfate twice at an interval of 52days. After the first ingestion, neurologic symptoms including visual loss, myalgia, and weakness in legs developed about 40days after the development of acute gastrointestinal symptoms and alopecia. After the second ingestion, neurologic symptoms deteriorated rapidly and severely without gastrointestinal or cutaneous symptoms. Brain magnetic resonance imaging exhibited bilateral optic nerve atrophy. Nerve conduction studies revealed severe peripheral neuropathies in legs. Thallium intoxication was confirmed by an increase in urine thallium egestion. Most of the neurologic manifestations ameliorated in two years, but the visual loss persisted. The source of thallium ingestion was unraveled afterward because a murder suspect in another homicidal assault confessed the forepast adulteration. This discriminating clinical course may be attributable to the cumulative neurotoxicity due to the longer washout-time of thallium in the nervous system than other organs. It is noteworthy that the divisional thallium intoxication may manifest as progressive optic and peripheral neuropathy without gastrointestinal or cutaneous symptoms. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Deterioration of gait and balance over time

    DEFF Research Database (Denmark)

    Kreisel, Stefan H; Blahak, Christian; Bäzner, Hansjörg

    2013-01-01

    Cross-sectional studies have shown an association between the severity of age-related white matter change (ARWMC) and lower body motor function. However, the association between prevalent ARWMC and incident deterioration of balance and gait remains insufficiently investigated. This study investig......Cross-sectional studies have shown an association between the severity of age-related white matter change (ARWMC) and lower body motor function. However, the association between prevalent ARWMC and incident deterioration of balance and gait remains insufficiently investigated. This study...... relevance: given the increasing use of neuroimaging, incidental white matter pathology is common; being able to delineate natural trajectories of balance and gait function given ARWMC may improve patient advice and help optimize allocation of care....

  11. The connection of hydronephrosis and microcirculation deterioration

    Directory of Open Access Journals (Sweden)

    Vorobets Dmytro

    2016-09-01

    Full Text Available In this study, we have analyzed the influence of hydronephrosis upon the microcirculation system, in situations of pyeloureteral junction obstruction. Herein, bulbar conjunctiva has been chosen as the object of this biomicroscopic study because of its simplicity and the method availability in clinic practice. In fulfilling this work, we ascertained the connections between extravascular, intravascular, vascular and general conjunctival indices of the patients before radical and paliatic correction of the pyeloureteral junction obstruction (i.e. by open and laparoscopic pyeloplasty, endopyelotomy, laser resection and balloon dilatation. We concluded that, apart from the proved deterioration of kidney function, systemic deteriorations of microcirculation may be observed in situations of clinically marked hydronephrosis, according to the results of radioisotope renography and excretory urography.

  12. Bayesian approaches for detecting significant deterioration

    International Nuclear Information System (INIS)

    Roed, Willy; Aven, Terje

    2009-01-01

    Risk indicators can provide useful input to risk management processes and are given increased attention in the Norwegian petroleum industry. Examples include indicators expressing the proportion of test failures of safety and barrier systems. Such indicators give valuable information about the performance of the systems and provide a basis for trend evaluations. Early warning of a possible deterioration is essential due to the importance of the systems in focus, but what should be the basis for the warning criterion? This paper presents and discusses several Bayesian approaches for the establishment of a warning criterion to disclose significant deterioration. The Norwegian petroleum industry is the starting point for this paper, but the study is relevant for other application areas as well

  13. Analysis of Pitch Gear Deterioration using Indicators

    DEFF Research Database (Denmark)

    Nielsen, Jannie Jessen; Sørensen, John Dalsgaard

    2011-01-01

    This work concerns a case study in the context of risk-based operation and maintenance of offshore wind turbines. For wind turbines with electrical pitch systems, deterioration can generally be observed at the pitch gear teeth; especially at the point where the blades are located during normal...... of the damage, and can be used for Bayesian updating of a damage model used for risk-based decision making. For this decision problem, the risk of failure should be compared to the cost of preventive maintenance. The hypothesis that the maximum pitch motor torque is an indicator of the damage size is supported...... changes in the temperature are the primary cause of the decrease. A model is established to remove the effect of the explained variation, and it is investigated if deterioration can be detected as changes in the peak torque. A small increase could be detected after the maintenance, but before...

  14. The behaviour of concrete under attack of liquid steel

    International Nuclear Information System (INIS)

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

    1983-01-01

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

  15. Using biological and physico-chemical test methods to assess the role of concrete mixture design in resistance to microbially induced corrosion

    Science.gov (United States)

    House, Mitchell Wayne

    to evaluate performance of concrete specimens under conditions designed to accelerate MIC. Concrete specimens representing 12 mixture designs were inoculated with 5 species of Thiobacillus bacteria and placed in a biological growth chamber designed to encourage bacterial growth and sulfuric acid production by optimizing temperature, delivering necessary nutrients, and providing hydrogen sulfide gas. Results indicate that using supplementary cementitious materials, limestone aggregates, and sulfate resistant cement can improve resistance to MIC. It is interesting to note that this study showed that unlike many other durability problems the role of water to cement ratio was unclear. The second method presented is a sulfuric acid immersion study designed to evaluate the resistance of 12 concrete mixture designs to 5 concentrations of sulfuric acid. Experimental protocols (like those in ASTM) previously considered trivial were found to have a dramatic effect on experimental results. It was found that using supplementary cementitious materials, limestone coarse aggregate, and sulfate resistant cement can increase concrete resistance to moderate sulfuric acid concentrations. The primary damage mechanism was observed to change depending on sulfuric acid concentration. Rapid deterioration of specimens exposed to aggressive sulfuric acid solutions indicates that degradation of concrete under the most severe MIC conditions (i.e., a pH concrete mixture proportions. A holistic approach is needed for these situations that considers environmental conditions as well.

  16. A new deteriorated energy-momentum tensor

    International Nuclear Information System (INIS)

    Duff, M.J.

    1982-01-01

    The stress-tensor of a scalar field theory is not unique because of the possibility of adding an 'improvement term'. In supersymmetric field theories the stress-tensor will appear in a super-current multiplet along with the sypersymmetry current. The general question of the supercurrent multiplet for arbitrary deteriorated stress tensors and their relationship to supercurrent multiplets for models with gauge antisymmetric tensors is answered for various models of N = 1, 2 and 4 supersymmetry. (U.K.)

  17. Evaluation of recycled concrete as aggregate in new concrete pavements.

    Science.gov (United States)

    2014-04-01

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

  18. 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

  19. Deterioration and fermentability of energy cane juice

    Directory of Open Access Journals (Sweden)

    Sandra Regina Ceccato-Antonini

    Full Text Available ABSTRACT: The main interest in the energy cane is the bioenergy production from the bagasse. The juice obtained after the cane milling may constitute a feedstock for the first-generation ethanol units; however, little attention has been dedicated to this issue. In order to verify the feasibility of the energy cane juice as substrate for ethanol production, the objectives of this research were first to determine the microbiological characteristics and deterioration along the time of the juices from two clones of energy cane (Type I and second, their fermentability as feedstock for utilization in ethanol distilleries. There was a clear differentiation in the bacterial and yeast development of the sugarcane juices assayed, being much faster in the energy canes than in sugarcane. The storage of juice for 8 hours at 30oC did not cause impact in alcoholic fermentation for any sample analyzed, although a significant bacterial growth was detected in this period. A decrease of approximately seven percentage points in the fermentative efficiency was observed for energy cane juice in relation to sugarcane in a 24-hour fermentation cycle with the baking yeast. Despite the faster deterioration, the present research demonstrated that the energy cane juice has potential to be used as feedstock in ethanol-producing industries. As far as we know, it is the first research to deal with the characteristics of deterioration and fermentability of energy cane juices.

  20. Condition monitoring and maintenance of nuclear power plant concrete structures

    International Nuclear Information System (INIS)

    Orr, R.; Prasad, N.

    1988-01-01

    Nuclear power plant concrete structures are potentially subject to deterioration due to several environmental conditions, including weather exposure, ground water exposure, and sustained high temperature and radiation levels. The nuclear power plant are generally licensed for a term of 40 years. In order to maximize the return from the existing plants, feasibility studies are in progress for continued operation of many of these plants beyond the original licensed life span. This paper describes a study that was performed with an objective to define appropriate condition monitoring and maintenance procedures. A timely implementation of a condition monitoring and maintenance program would provide a valuable database and would provide justification for extension of the plant's design life. The study included concrete structures such as the containment buildings, interior structures, basemats, intake structures and cooling towers. Age-related deterioration at several operating power plants was surveyed and the potential degradation mechanisms have been identified

  1. LIGHTWEIGHT CONCRETE BASED GRANSHLAK

    Directory of Open Access Journals (Sweden)

    NETESA M. I.

    2016-02-01

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

  2. Use of Macro Basalt Fibre Concrete for Marine Applications

    OpenAIRE

    Mohammadi Mohaghegh, Ali

    2016-01-01

    Deterioration of concrete structures due to the corrosion of embedded steel is a well-known universal problem. Norway with its numerous bridges, ports, offshore and floating structures along its coastline, is also encountered with corrosion degradation. The harsh environment of the Norwegian Sea regarding its low temperature, wind, and waves, makes the design and construction of marine structures more demanding. In recent years, usage of sustainable composite materials in the field of structu...

  3. Identification of the sources of organic compounds that decalcify cement concrete and generate alcohols and ammonia gases

    Energy Technology Data Exchange (ETDEWEB)

    Tomoto, Takashi [Technical Research Institute, Obayashi Road Corporation, 4-640 Shimokiyoto, Kiyose, Tokyo, 204-0011 (Japan); Moriyoshi, Akihiro [Material Science Laboratory, Hokkaido University, 2-1-9-10 Kiyota, Kiyota-ku, Sapporo, 004-0842 (Japan); Sakai, Kiyoshi [Department of Environmental Health, Nagoya City Public Health Research Institute, 1-11 Hagiyama-cho, Mizuho-ku, Nagoya, 467-8615 (Japan); Shibata, Eiji [Department of Health and Psychosocial Medicine, Aichi Medical University School of Medicine, Nagakute-cho, Aichi, 480-1195 (Japan); Kamijima, Michihiro [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550 (Japan)

    2009-09-15

    This study identifies the emission sources of various types of airborne organic compounds, which deteriorate cement concrete by penetrating into the concrete together with moisture. The study used high-performance liquid chromatography and gas chromatograph mass spectrometry. The results show that the types of organic compounds contained in decalcified cement concrete were very similar to those found in the total suspended compounds in the air, and that the source of the emissions was particles of exhaust from diesel vehicles and radial tires used in summer. Such organic compounds include substances suspected of having endocrine disrupting properties. Hydrolysis occurs when these substances penetrate into highly alkaline cement concrete, and leads to deterioration of the cement concrete and the release of alcohols and ammonia gases which pollute indoor air and may be a cause of the sick building syndrome. (author)

  4. The use of Impact-Echo and Spectral-Analysis-of-Surface-Waves methods for the concrete investigation of Rogers Dam spillway structure

    International Nuclear Information System (INIS)

    Olson, L.D.; Sack, D.A.; Chan, Y.F.; Gilmore, R.T.; Christy, J.T.; Dumont, M.F.

    1994-01-01

    IE and SASW NDT methods were employed to investigate the concrete conditions of the Rogers Hydro Station's concrete spillway. The results showed that the surface gunite/shotcrete on the majority of the piers and walls was delaminated from the interior sound concrete and that there was a significant amount of sound concrete in the interior cores of the piers and walls. The NDT results correspond well in general trend with those of the concrete coring performed in 1988 and 1991; however, because of the greatly varying concrete conditions and additional concrete deterioration since 1988 when the majority of the horizontal cores were taken, a direct point-per-point comparison cannot be made. The NDT results correspond well with the as-found conditions on Pier 1 and on the east abutment wall except that the deep degradation (SASW results) conditions on the west face of Pier 1 did not exist. The highly deteriorated nature of the concrete could have contributed to the lower wave velocities. The cracking conditions below the demolition line were not verified. Some of the IE echoes could have been caused by the boundary conditions, in view of the highly fractured nature of the surface concrete/shotcrete and the very low strength and deteriorated concrete at the construction joints

  5. Magnesium oxychloride cement concrete

    Indian Academy of Sciences (India)

    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 ...

  6. Radiographic testing of concrete

    International Nuclear Information System (INIS)

    Porter, James F.

    1997-01-01

    The increase in construction activity in the Philippines, reinforced concrete building is still a favorite among designers, because it is much cheaper to build and it requires qualified welders, etc. and extensive nondestructive testing and inspection of metals, welds and castings. Of all the techniques radiography is widely used for concrete

  7. Concrete deck material properties.

    Science.gov (United States)

    2009-01-01

    The two-fold focus of this study was (a) to develop an understanding of the mechanisms responsible for causing : cracking in the concrete; and (b) to study the influence of the local materials on the performance of NYSDOTs HP : concrete mixture. R...

  8. 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.

  9. Danish High Performance Concretes

    DEFF Research Database (Denmark)

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

    1994-01-01

    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...... concretes, workability, ductility, and confinement problems....

  10. 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...

  11. 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

  12. Radiation shielding concrete

    International Nuclear Information System (INIS)

    Kunishima, Shigeru.

    1990-01-01

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

  13. 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..

  14. Bridge deterioration models to support Indiana's bridge management system.

    Science.gov (United States)

    2016-02-01

    An effective bridge management system that is equipped with reliable deterioration models enables agency engineers to carry out : monitoring and long-term programming of bridge repair actions. At the project level, deterioration models help the agenc...

  15. Deterioration of J-bar reinforcement in abutments and piers.

    Science.gov (United States)

    2011-12-31

    Deterioration and necking of J-bars has been reportedly observed at the interface of the footing and stem wall during the demolition : of older retaining walls and bridge abutments. Similar deterioration has been reportedly observed between the pier ...

  16. Investigation regarding bridge expansion joints deterioration in pakistan and its remedial measures

    International Nuclear Information System (INIS)

    Ajwad, A.

    2014-01-01

    The Concrete bridges are a vital part of highway infrastructure in Pakistan. The main problem that exists is the deterioration of most of them over the past 20 years or so. The main reason for this is the deviation from specified construction procedures and the negligence of the maintenance departments due to several reasons. At the moment National Highway Authority (NHA) owns about 5000 bridges in number across the country and according to a survey, about 30 percent of them are either not up to the mark or are out of service. The fund that NHA reserves every year for the maintenance purposes ranges from PKR 500 to 600 million which is very limited when it comes across the scope of the work. It means that expensive testing and retrofitting techniques that need to be implemented can never be achieved practically. This research is focused on case studies involving deterioration of bridge expansion joints only. All the deficiencies with their root causes and remedial measures are discussed in detail. The research is based upon wide experience of authors and will prove to be a cherished standard and beneficial reference article for working engineers engaged in fresh construction as well as renovation and repairs of concrete highway bridges. (author)

  17. Microbial healing of cracks in concrete: a review.

    Science.gov (United States)

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

    2017-11-01

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

  18. Evaluation and rehabilitation of corrosion damaged reinforced concrete structures

    International Nuclear Information System (INIS)

    Paul, I.S.

    1999-01-01

    For the last two decades, rehabilitation of corrosion damaged concrete structures has been one of the most important challenges faced by the construction industry throughout the world. The extent of the damage is significant in cold climates and also in hot and humid climates. In both cases, the corrosion is invariably initiated by ingress of salts into the concrete either from de-icing salts used on roads, or from salt-laden air, soils or ground water. However, there is a contrast in sites of distress in the two climatic regions mentioned above. In cold climates, where de-icing salts are used, the damage is generally to superstructures and is therefore visible, but in hot, humid coastal regions damage is primarily in the substructures and may not be so clearly apparent. This paper presents the corrosion mechanism in concrete deterioration, the methods of evaluation of the damaged structures, and rehabilitation strategies. A case history of a concrete rehabilitation project is included together with some lessons learned in rehabilitation of corrosion damaged structures. Recommendations are made for maintenance of concrete structures and a warning is issued that salt run-off from roads in cold climates may cause distress in below ground concrete structures, similar to structures in hot and humid climates with saline groundwater and soils. (author)

  19. Freeze-thaw durability of air-entrained concrete.

    Science.gov (United States)

    Shang, Huai-Shuai; Yi, Ting-Hua

    2013-01-01

    One of the most damaging actions affecting concrete is the abrupt temperature change (freeze-thaw cycles). The types of deterioration of concrete structures by cyclic freeze-thaw can be largely classified into surface scaling (characterized by the weight loss) and internal crack growth (characterized by the loss of dynamic modulus of elasticity). The present study explored the durability of concrete made with air-entraining agent subjected to 0, 100, 200, 300, and 400 cycles of freeze-thaw. The experimental study of C20, C25, C30, C40, and C50 air-entrained concrete specimens was completed according to "the test method of long-term and durability on ordinary concrete" GB/T 50082-2009. The dynamic modulus of elasticity and weight loss of specimens were measured after different cycles of freeze-thaw. The influence of freeze-thaw cycles on the relative dynamic modulus of elasticity and weight loss was analyzed. The findings showed that the dynamic modulus of elasticity and weight decreased as the freeze-thaw cycles were repeated. They revealed that the C30, C40, and C50 air-entrained concrete was still durable after 300 cycles of freeze-thaw according to the experimental results.

  20. Study of water permeability in concrete by neutron and gamma-ray techniques

    International Nuclear Information System (INIS)

    Abd El-Monem, A.M.M.

    2010-01-01

    water infiltration in various building materials , namely concrete used for buildings basement and underwater construction is the main concern of the studies performed in this thesis. The studies aim to develop a nuclear techniques for investigation a concrete mixes with different additives capable to decrease concrete porosity and intern resist water propagation inside concrete materials without any deterioration of concrete physical and mechanical properties . These issues were achieved through the preparation of ordinary concrete mixes with different percentages of silica fume. Concrete samples of different shape and geometries were made to study water diffusion when the concrete samples are submerged in water for different periods of time. The concrete samples were first sealed by molten asphalt from all sides expect two opposite faces to ensure water migration only along one direction. Water infiltration in concrete samples with different percentages of silica fume and submerged in tap and seawater for different periods of time was studied by neutrons and gamma techniques. Also, water propagation in mortar samples with different percentages of silica fume was studied by electrical methods based on measuring the variation in electrical conductivity of these samples.

  1. 40 CFR 52.1165 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.1165 Section 52.1165 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air... deterioration of air quality. (b) Regulation for preventing significant deterioration of air quality. The...

  2. 40 CFR 52.2729 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.2729 Section 52.2729 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air... deterioration of air quality. (b) Regulations for preventing significant deterioration of air quality. The...

  3. 40 CFR 52.1689 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.1689 Section 52.1689 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air... deterioration of air quality. (b) Regulations for preventing significant deterioration of air quality. The...

  4. 40 CFR 52.1929 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.1929 Section 52.1929 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) Regulation for preventing significant deterioration of air... preventing significant deterioration of air quality. [56 FR 5656, Feb. 12, 1991, as amended at 68 FR 11324...

  5. 40 CFR 52.1234 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.1234 Section 52.1234 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air... deterioration of air quality. (b) Regulations for preventing significant deterioration of air quality. The...

  6. 40 CFR 52.2827 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.2827 Section 52.2827 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air... deterioration of air quality. (b) Regulations for preventing significant deterioration of air quality. The...

  7. 40 CFR 52.1603 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.1603 Section 52.1603 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air... deterioration of air quality. (b) Regulations for preventing significant deterioration of air quality. The...

  8. 40 CFR 52.1180 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.1180 Section 52.1180 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air... deterioration of air quality. (b) Regulations for preventing significant deterioration of air quality. The...

  9. 40 CFR 52.2451 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.2451 Section 52.2451 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air... Quality Deterioration. (b) Regulations for preventing significant deterioration of air quality. The...

  10. 40 CFR 52.2779 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.2779 Section 52.2779 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air... deterioration of air quality. (b) Regulations for preventing significant deterioration of air quality. The...

  11. 40 CFR 52.2676 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.2676 Section 52.2676 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air... deterioration of air quality. (b) Regulations for preventing significant deterioration of air quality. The...

  12. 40 CFR 52.499 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.499 Section 52.499 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air... deterioration of air quality. (b) Regulations for preventing significant deterioration of air quality. The...

  13. 40 CFR 52.2497 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.2497 Section 52.2497 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air... deterioration of air quality. (b) Regulations for preventing significant deterioration of air quality. The...

  14. 40 CFR 52.1884 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.1884 Section 52.1884 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air... deterioration of air quality. (b) Regulations for preventing significant deterioration of air quality. The...

  15. 40 CFR 52.2528 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.2528 Section 52.2528 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The requirements of Sections 160 through 165 of the Clean Air... Quality Deterioration. (b) Regulations for Preventing Significant Deterioration of Air Quality, the...

  16. 40 CFR 52.530 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Significant deterioration of air quality. 52.530 Section 52.530 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... deterioration of air quality. (a) EPA approves the Florida Prevention of Significant Deterioration program, as...

  17. Application of Chemical Kinetics to Deterioration of Foods.

    Science.gov (United States)

    Labuza, T. P.

    1984-01-01

    Possible modes of food deterioration (such as microbial decay, nonenzymatic browning, senescence, lipid oxidation) are reviewed. A basic mathematical approach to the kinetics of food deterioration, kinetic approach to accelerating shelf-life deterioration, and shelf-life predictions are discussed. (JN)

  18. 40 CFR 86.432-78 - Deterioration factor.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Deterioration factor. 86.432-78... 1978 and Later New Motorcycles, General Provisions § 86.432-78 Deterioration factor. (a) Deterioration factors shall be developed for each test vehicle from the emission test results. A separate factor shall...

  19. Monitoring corrosion in reinforced concrete structures

    Science.gov (United States)

    Kung, Peter; Comanici, Maria I.

    2014-06-01

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

  20. Concrete sample point: 304 Concretion Facility

    International Nuclear Information System (INIS)

    Rollison, M.D.

    1995-01-01

    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

  1. Reliability updating with inspection and monitoring data in deteriorating reinforced concrete slabs

    OpenAIRE

    Straub, D.

    2015-01-01

    Corrosion is a common phenomenon in engineering structures; examples include corrosion of the reinforcement in RC structures, corrosion of steel plates in ship hulls or localized corrosion in pipelines. These corrosion mechanisms are generally subject to random spatial variability, due to random changes in in-fluencing factors over space. When assessing the effect of inspections and measurements on the reliability of such structures, it is essential to account for this spatial variability: Du...

  2. Acoustic emission monitoring of recycled aggregate concrete under bending

    Science.gov (United States)

    Tsoumani, A. A.; Barkoula, N.-M.; Matikas, T. E.

    2015-03-01

    The amount of construction and demolition waste has increased considerably over the last few years, making desirable the reuse of this waste in the concrete industry. In the present study concrete specimens are subjected at the age of 28 days to four-point bending with concurrent monitoring of their acoustic emission (AE) activity. Several concrete mixtures prepared using recycled aggregates at various percentages of the total coarse aggregate and also a reference mix using natural aggregates, were included to investigate their influence of the recycled aggregates on the load bearing capacity, as well as on the fracture mechanisms. The results reveal that for low levels of substitution the influence of using recycled aggregates on the flexural strength is negligible while higher levels of substitution lead into its deterioration. The total AE activity, as well as the AE signals emitted during failure, was related to flexural strength. The results obtained during test processing were found to be in agreement with visual observation.

  3. Influence of Wind Pressure on the Carbonation of Concrete.

    Science.gov (United States)

    Zou, Dujian; Liu, Tiejun; Du, Chengcheng; Teng, Jun

    2015-07-24

    Carbonation is one of the major deteriorations that accelerate steel corrosion in reinforced concrete structures. Many mathematical/numerical models of the carbonation process, primarily diffusion-reaction models, have been established to predict the carbonation depth. However, the mass transfer of carbon dioxide in porous concrete includes molecular diffusion and convection mass transfer. In particular, the convection mass transfer induced by pressure difference is called penetration mass transfer. This paper presents the influence of penetration mass transfer on the carbonation. A penetration-reaction carbonation model was constructed and validated by accelerated test results under high pressure. Then the characteristics of wind pressure on the carbonation were investigated through finite element analysis considering steady and fluctuating wind flows. The results indicate that the wind pressure on the surface of concrete buildings results in deeper carbonation depth than that just considering the diffusion of carbon dioxide. In addition, the influence of wind pressure on carbonation tends to increase significantly with carbonation depth.

  4. AN OPTIMAL MAINTENANCE MANAGEMENT MODEL FOR AIRPORT CONCRETE PAVEMENT

    Science.gov (United States)

    Shimomura, Taizo; Fujimori, Yuji; Kaito, Kiyoyuki; Obama, Kengo; Kobayashi, Kiyoshi

    In this paper, an optimal management model is formulated for the performance-based rehabilitation/maintenance contract for airport concrete pavement, whereby two types of life cycle cost risks, i.e., ground consolidation risk and concrete depreciation risk, are explicitly considered. The non-homogenous Markov chain model is formulated to represent the deterioration processes of concrete pavement which are conditional upon the ground consolidation processes. The optimal non-homogenous Markov decision model with multiple types of risk is presented to design the optimal rehabilitation/maintenance plans. And the methodology to revise the optimal rehabilitation/maintenance plans based upon the monitoring data by the Bayesian up-to-dating rules. The validity of the methodology presented in this paper is examined based upon the case studies carried out for the H airport.

  5. Ageing management of concrete structure

    International Nuclear Information System (INIS)

    Parthipan, P.; Ramaprasad, G.S.; Senthil, R.

    2006-01-01

    It is a generally accepted fact that while designing a concrete structure the durability parameters of construction materials should be evaluated as carefully as possible like other properties such as mechanical, physical and chemical properties. No material is inherently durable as result of environmental interaction with microstructure and consequently, the properties of the materials change with time due to weathering action, chemical attack, abrasion or any mode of degradation. The main cause of ageing on structure, water, which is primary for both creation and destruction on many natural materials. In porous materials, water creates different types of physical and chemical process of degradation. The water movement through porous materials are controlled by the permeability of the respective materials. The rate of deterioration is affected by type of concentration of ions present in the water and chemical deposition of materials. Controlling weathering action, chemical attack, abrasion and selecting good quality construction material and methods of construction can increase the service life of the structure. (author)

  6. Maintenance planning for a deteriorating production process

    International Nuclear Information System (INIS)

    Ahmadi, Reza; Fouladirad, Mitra

    2017-01-01

    We consider a system subject to degradation, more precisely a production process with three quality states evolving according to a homogeneous Markov process. The degradation decreases the income generated by the system. To maintain revenue stream and prevent the loss of revenue, the system is inspected according to a Markov-modulated Poisson process. It is assumed that each inspection at time t incurs a time dependent cost. Each inspection improves the system health and therefore the degradation level jumps to a less deteriorated state. In absence of inspections, the system state is prone to shift to a more deteriorated state with a constant rate. The problem is to determine an optimal operating (stopping) time which truly balances some flow of income and increasing costs due to inspections, and so maximizes the expected gain of the proposed policy. To demonstrate the applicability of the explored approach and its effectiveness, some numerical results are provided. - Highlights: • An integrated model based on a quality state-dependent reward structure is explored. • The model allows the revenue stream responds to variation in the quality state. • The production process is inspected according to a Markovmodulated Poisson process. • Assuming a Markovian structure, we predict the quality state behavior. • We determine an optimal production run length based on a stopping decision rule.

  7. Early warnings of heart rate deterioration.

    Science.gov (United States)

    Almeida, Vania G; Nabney, Ian T

    2016-08-01

    Hospitals can experience difficulty in detecting and responding to early signs of patient deterioration leading to late intensive care referrals, excess mortality and morbidity, and increased hospital costs. Our study aims to explore potential indicators of physiological deterioration by the analysis of vital-signs. The dataset used comprises heart rate (HR) measurements from MIMIC II waveform database, taken from six patients admitted to the Intensive Care Unit (ICU) and diagnosed with severe sepsis. Different indicators were considered: 1) generic early warning indicators used in ecosystems analysis (autocorrelation at-1-lag (ACF1), standard deviation (SD), skewness, kurtosis and heteroskedasticity) and 2) entropy analysis (kernel entropy and multi scale entropy). Our preliminary findings suggest that when a critical transition is approaching, the equilibrium state changes what is visible in the ACF1 and SD values, but also by the analysis of the entropy. Entropy allows to characterize the complexity of the time series during the hospital stay and can be used as an indicator of regime shifts in a patient's condition. One of the main problems is its dependency of the scale used. Our results demonstrate that different entropy scales should be used depending of the level of entropy verified.

  8. OPTIMIZATION OF PRESERVATIVE FOR PROTECTION OF CONCRETE PAVEMENT OF HIGHWAYS

    Directory of Open Access Journals (Sweden)

    M. K. Pshembaev

    2018-01-01

    Full Text Available Disadvantages of road concrete pavement quite well known professionals-standards. They were mainly low elasticity modulus asphaltic concrete, as well as a fairly rapid aging of asphalt concrete core component-bitumen. And, as a consequence, is relatively low durability of the coating, the need for frequent repair. To some extent, cement concrete cover signifi cantly outperform this index of asphalt, convinces experience roads of Germany, the United States and other countries. The correct structure of concrete, overall compliance technology laying concrete, comprehensive quality control production  work, sufficient technical personnel qualifications provide long defect-free work road re-coated. However, violations by manufacture of works or in the process of exploitation, particularly in the harsh conditions of freezing and thawing, saturation-drying, especially under the influence of salts-defrosting, cause defects, reduce its durability. There are two directions of increase of durability of the coating. Firstly, it is the primary protection is the creation of concrete with minimal possible on data components mixture water cement ratio that provides reception of concrete with minimum porosity and consequently with maximum durability. Secondly, the secondary protection, providing increased resistance already ready-mixed concrete cover external aggressive actions. In this case against the background of other ways quite promising looks impregnation of the surface concrete integrated structure. Composition must contain multiple components, primarily water repellents, preventing penetration of fluid into the body of the concrete, and finely dispersed silica sol in particular silica, providing reduction of the porosity of the surface layers of concrete by interacting with the free calcium hydroxide. The problem of optimization of impregnation structure and is dedicated to this work.

  9. 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.

  10. Electrokinetic decontamination of concrete

    International Nuclear Information System (INIS)

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

    1996-01-01

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

  11. Steel fiber reinforced concrete

    International Nuclear Information System (INIS)

    Baloch, S.U.

    2005-01-01

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

  12. Analysis of time-dependent reliability of degenerated reinforced concrete structure

    Directory of Open Access Journals (Sweden)

    Zhang Hongping

    2016-07-01

    Full Text Available Durability deterioration of structure is a highly random process. The maintenance of degenerated structure involves the calculation of the reliability of time-dependent structure. This study introduced reinforced concrete structure resistance decrease model and related statistical parameters of uncertainty, analyzed resistance decrease rules of corroded bending element of reinforced concrete structure, and finally calculated timedependent reliability of the corroded bending element of reinforced concrete structure, aiming to provide a specific theoretical basis for the application of time-dependent reliability theory.

  13. Effect of insulating concrete forms in concrete compresive strength

    Science.gov (United States)

    Martinez Jerez, Silvio R.

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

  14. Concrete and criticality

    International Nuclear Information System (INIS)

    Carter, R.D.

    1978-01-01

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

  15. Biodecontamination of concrete

    International Nuclear Information System (INIS)

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

    1996-01-01

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

  16. Mass transfer in water-saturated concretes

    International Nuclear Information System (INIS)

    Atkinson, A.; Claisse, P.A.; Harris, A.W.; Nickerson, A.K.

    1990-01-01

    Cements and concretes are often considered as components of barriers for the containment of radioactive waste. The performance of such materials as mainly physical barriers to the transport of dissolved radionuclides depends on the mass transfer characteristics of the material. In particular the diffusion and sorption behavior of the radionuclides and the water permeability are important. These parameters also influence how the chemistry of the concrete is imposed on the repository. In addition, the transport of gas through concrete controls the way in which gases escape from the repository. Diffusion and gas transport have been measured in a variety of cementitious materials, covering both structural concretes and cementitious backfills; all possible repository construction materials. Measurements have been made using aqueous iodide, strontium and caesium ions and tritiated water as diffusants. The results show that the diffusion of tritiated water is more rapid than that of other species, whilst the transport of strontium and caesium is hindered by sorption; particularly in materials containing blast furnace slag. The transport of gas in these materials has been found to be very sensitive to the degree of water saturation and is extremely low in fully saturated structural concretes. Cementitious backfills have, nevertheless, been identified that have appreciable gas transport even when almost water saturated. The consequences of the results for the performance of cementitious barriers are discussed

  17. 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.

  18. Concrete = aggregate, cement, water?

    International Nuclear Information System (INIS)

    Jelinek, J.

    1990-01-01

    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

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

    OpenAIRE

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

    2011-01-01

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

  20. COMPARATIVE STUDY OF GLASS FIBRE CONCRETE AND NORMAL CONCRETE

    OpenAIRE

    Mr.Yogesh S.Lanjewar*

    2018-01-01

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

  1. A review on condition-based maintenance optimization models for stochastically deteriorating system

    International Nuclear Information System (INIS)

    Alaswad, Suzan; Xiang, Yisha

    2017-01-01

    Condition-based maintenance (CBM) is a maintenance strategy that collects and assesses real-time information, and recommends maintenance decisions based on the current condition of the system. In recent decades, research on CBM has been rapidly growing due to the rapid development of computer-based monitoring technologies. Research studies have proven that CBM, if planned properly, can be effective in improving equipment reliability at reduced costs. This paper presents a review of CBM literature with emphasis on mathematical modeling and optimization approaches. We focus this review on important aspects of the CBM, such as optimization criteria, inspection frequency, maintenance degree, solution methodology, etc. Since the modeling choice for the stochastic deterioration process greatly influences CBM strategy decisions, this review classifies the literature on CBM models based on the underlying deterioration processes, namely discrete- and continuous-state deterioration, and proportional hazard model. CBM models for multi-unit systems are also reviewed in this paper. This paper provides useful references for CBM management professionals and researchers working on CBM modeling and optimization. - Highlights: • A review on Condition-based maintenance (CBM) optimization models is presented. • The CBM models are classified based on the underlying deterioration processes. • Existing CBM models for both single- and multi-unit systems are reviewed. • Future essential research directions on CBM are identified.

  2. Electrokenitic Corrosion Treatment of Concrete

    Science.gov (United States)

    Cardenas, Henry E (Inventor)

    2015-01-01

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

  3. Electrokinetic Strength Enhancement of Concrete

    Science.gov (United States)

    Cardenas, Henry E. (Inventor)

    2016-01-01

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

  4. 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.

  5. Compatibility of repair concretes in the aggressive environment of the South of Iran

    International Nuclear Information System (INIS)

    Parhizkar, T.; Ramezaniapour, A.A.; Hillemeier, B.; Ghasemi, A.M.R.; Mozafari, N.

    2006-01-01

    Deterioration of reinforced concrete structures, namely due to corrosion of reinforcement, in the south of Iran, on the coasts of the Gulf region has become a major problem in recent years. The high cost involved in repairing and strengthening of deteriorated concrete structures in this region makes it essential that the repair materials used are compatible enough to match the residual service life of the structure. This paper presents the engineering and compatibility-related properties of two repair concretes containing silica fume and styrene butadiene rubber latex (SBR) under simulated hot and humid conditions similar to the aggressive environment of the south of Iran. A normal cement-based repair concrete was used as control. Mechanical properties were assessed and the dimension stability of the repair concrete was also evaluated. The results of this investigation show that the concrete containing silica fume and the polymer-modified concrete are appropriate materials for repair in the severe environmental conditions of the Gulf region. (author)

  6. Experimental study on the performance of pervious concrete

    Science.gov (United States)

    Liu, Haojie; Liu, Rentai; Yang, Honglu; Ma, Chenyang; Zhou, Heng

    2018-02-01

    With the construction of sponge city, the pervious concrete material has been developed rapidly. A high-performance pervious concrete is developed by using cement, silica fume (SF) and superplasticizer (SP). The effects of SF, SP, aggregate size, water-cement ration and aggregate-cement ratio on the permeability coefficient, compressive strength and flexural strength are studied by controlling variables, and exploring the corrosion resistance and abrasion resistance of pervious concrete. The results show that using 0.5% SP, 5% SF and small aggregate can greatly improve the strength. There is an optimum value for water-cement ratio to make the strength and permeability coefficient maximum. Compared to ordinary pervious concrete, the corrosion resistance and abrasion resistance of this pervious concrete are very good.

  7. Effect of manufactured sand on the durability characteristics of concrete

    Directory of Open Access Journals (Sweden)

    S. S. SARAVANAN

    2016-12-01

    Full Text Available Concrete is the most sought after material due to increase in construction activities and infrastructural developments. Availability of natural sand is decreasing thereby increase in the cost of construction. In the present work undertaken, an attempt has been made to give an alternative to natural sand. Optimization of replacement of natural sand with manufactured sand in concrete, durability studies such as water absorption, rapid chloride permeability test, sorptivity, acid resistance, alkaline resistance, impact resistance and abrasion resistance of M40 and M50 grades of concrete have been studied with manufactured sand as fine aggregate and compared the results with the conventional sand concrete. The results shows that there is an increase in the durability properties up to 70 % level of replacements of sand with manufactured sand as fine aggregate and for 100 % use of manufactured sand also gives the better durability than the conventional sand concrete.

  8. A historical examination of concrete

    International Nuclear Information System (INIS)

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

    1987-01-01

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

  9. Alkali Release from Typical Danish Aggregates to Potential ASR Reactive Concrete

    DEFF Research Database (Denmark)

    Thomsen, Hans Christian Brolin; Grelk, Bent; Barbosa, Ricardo Antonio

    Alkali-silica reaction (ASR) in concrete is a well-known deterioration mechanism affecting the long term durability of Danish concrete structures. Deleterious ASR cracking can be significantly reduced or prevented by limiting the total alkali content of concrete under a certain threshold limit......, which in Denmark is recommended to 3 kg/m3 Na2Oeq.. However, this threshold limit does not account for the possible internal contribution of alkali to the concrete pore solution by release from aggregates or external contributions from varies sources. This study indicates that certain Danish aggregates...... are capable of releasing more than 0.46 kg/m3 Na2Oeq. at 13 weeks of exposure in laboratory test which may increase the risk for deleterious cracking due to an increase in alkali content in the concrete....

  10. Measurement of reinforcement corrosion in concrete structures. Betonirakenteiden raudoituksen korroosion tutkiminen

    Energy Technology Data Exchange (ETDEWEB)

    Meuronen, A

    1992-03-01

    Ageing and aggressive enviromental conditions of concrete structures will result in deterioration of concrete and corrosion of steel in concrete. Corrosion of steel will in time result in the end of the service life or expensive renovations, unless corrosion of steel is noticed and renovated in time. Corrosion of steel in concrete can be found out by the present corrosion measurement methods, so that renovation can be started in right time. The report presents mainly on the basis of the literature references the following corrosion measurement methods: polarisation resistance, AC-impedance, electrical resistance probe, electrochemical noice and half-cell potential mapping. The half-cell potential mapping will be presented more precisely than the other corrosion measurement methods, for the potential mapping is the most used method. Concrete and Soils Laboratory of Imatran Voima Oy uses in the measurement of reinforcement corrosion the English, eight channel potential measuring equipment.

  11. Measurement of reinforcement corrosion in concrete structures; Betonirakenteiden raudoituksen korroosion tutkiminen

    Energy Technology Data Exchange (ETDEWEB)

    Meuronen, A

    1992-03-01

    Ageing and aggressive enviromental conditions of concrete structures will result in deterioration of concrete and corrosion of steel in concrete. Corrosion of steel will in time result in the end of the service life or expensive renovations, unless corrosion of steel is noticed and renovated in time. Corrosion of steel in concrete can be found out by the present corrosion measurement methods, so that renovation can be started in right time. The report presents mainly on the basis of the literature references the following corrosion measurement methods: polarisation resistance, AC-impedance, electrical resistance probe, electrochemical noice and half-cell potential mapping. The half-cell potential mapping will be presented more precisely than the other corrosion measurement methods, for the potential mapping is the most used method. Concrete and Soils Laboratory of Imatran Voima Oy uses in the measurement of reinforcement corrosion the English, eight channel potential measuring equipment.

  12. Anchorage in concrete construction

    CERN Document Server

    Eligehausen, Rolf; Silva, John F

    2013-01-01

    A comprehensive treatment of current fastening technology using inserts (anchor channels, headed stud), anchors (metal expansion anchor, undercut anchor, bonded anchor, concrete screw and plastic anchor) as well as power actuated fasteners in concrete. It describes in detail the fastening elements as well as their effects and load-bearing capacities in cracked and non-cracked concrete. It further focuses on corrosion behaviour, fire resistance and characteristics with earthquakes and shocks. It finishes off with the design of fastenings according to the European Technical Approval Guideline (ETAG 001), the Final Draft of the CEN Technical Specification 'Design of fastenings for use in concrete' and the American Standards ACI 318-05, Appendix D and ACI 349-01, Appendix B.

  13. Concrete Research Facility

    Data.gov (United States)

    Federal Laboratory Consortium — This is a 20,000-sq ft laboratory that supports research on all aspects of concrete and materials technology. The staff of this facility offer wide-ranging expertise...

  14. Prestressed concrete design

    CERN Document Server

    Hurst, MK

    1998-01-01

    This edition provides up-to-date guidance on the detailed design of prestressed concrete structures. All major topics are dealt with, including prestressed flat slabs, an important and growing application in the design of buildings.

  15. Magnesium oxychloride cement concrete

    Indian Academy of Sciences (India)

    TECS

    exposure to water and salt attack by replacing 10% magnesium chloride solution by magnesium sulphate solution ... Having tremendous load bearing capacity, it can withstand .... retention coefficients for similar concrete compositions.

  16. Improving concrete overlay construction.

    Science.gov (United States)

    2010-03-01

    Several road construction projects involving concrete overlays at the state and county levels in Iowa in 2009 were studied for : construction techniques and methods. The projects that were evaluated consisted of sites in four Iowa counties: Osceola, ...

  17. Concrete decontamination scoping tests

    International Nuclear Information System (INIS)

    Archibald, K.E.

    1995-01-01

    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

  18. Modeling reinforced concrete durability.

    Science.gov (United States)

    2014-06-01

    This project developed a next-generation modeling approach for projecting the extent of : reinforced concrete corrosion-related damage, customized for new and existing Florida Department of : Transportation bridges and suitable for adapting to broade...

  19. Investigation on lithium migration for treating alkali-silica reaction affected concrete

    NARCIS (Netherlands)

    Silva De Souza, L.M.; Polder, R.B.; Copuroglu, O.

    2014-01-01

    Alkali-silica reaction (ASR) is one of the major deterioration mechanisms that affect numerous concrete structures worldwide. During the reaction, hydroxyl and alkali (sodium and potassium ) ions react with certain siliceous compounds in the aggregate, forming a hygroscopic gel. The gel absorbs

  20. Novel shear capacity testing of ASR damaged full scale concrete bridge

    DEFF Research Database (Denmark)

    Schmidt, Jacob Wittrup; Hansen, Søren Gustenhoff; Barbosa, Ricardo Antonio

    2014-01-01

    A large number of concrete bridges in Denmark have to undergo wide-ranging maintenance work to prevent deterioration due to aggressive Alkali Silica Reaction (ASR). This destructive mechanism results in extensive cracking which is believed to affect the load carrying capacity of the structure...

  1. Electrochemical lithium migration to mitigate alkali-silica reaction in existing concrete structures

    NARCIS (Netherlands)

    Silva De Souza, L.M.

    2016-01-01

    Alkali-silica reaction (ASR) is a deterioration process that affects the durability of concrete structures worldwide. During the reaction, hydroxyl and alkali ions present in the pore solution react with reactive silica from the aggregate, forming a hygroscopic ASR gel. Alternatively, the silica

  2. Halophilic microbial communities in deteriorated buildings.

    Science.gov (United States)

    Adamiak, Justyna; Otlewska, Anna; Gutarowska, Beata

    2015-10-01

    Halophilic microorganisms were traditionally isolated from an aquatic environment. There has been little research conducted into halophiles inhabiting the terrestrial environment in which historic monuments deteriorate. Salt efflorescence deposited on the walls is an observed phenomenon on the surface of historic buildings, and would favour the growth of halophiles. However, some conditions have to be fulfilled in order for efflorescence to occur: (1) the presence of salts, (2) porosity, (3) a source of water. Salt crystallization influences the material structure (cracking, detachment, material loss), but active growth of halophilic microorganisms may be a serious threat to historic materials as well, leading to aesthetical changes such as coloured biofilms, orange to pink or even violet stains. This is why it is important to investigate halophilic microorganisms, taking into consideration both the environmental conditions they need to grow in, material characteristics they inhabit, the mechanisms they possess to cope with osmotic stress, and the methods that should be applied for their identification.

  3. Optimal Control Inventory Stochastic With Production Deteriorating

    Science.gov (United States)

    Affandi, Pardi

    2018-01-01

    In this paper, we are using optimal control approach to determine the optimal rate in production. Most of the inventory production models deal with a single item. First build the mathematical models inventory stochastic, in this model we also assume that the items are in the same store. The mathematical model of the problem inventory can be deterministic and stochastic models. In this research will be discussed how to model the stochastic as well as how to solve the inventory model using optimal control techniques. The main tool in the study problems for the necessary optimality conditions in the form of the Pontryagin maximum principle involves the Hamilton function. So we can have the optimal production rate in a production inventory system where items are subject deterioration.

  4. Core Characteristics Deterioration due to Plastic Deformation

    Science.gov (United States)

    Kaido, Chikara; Arai, Satoshi

    This paper discusses the effect of plastic deformation at core manufacturing on the characteristics of cores where non-oriented electrical steel sheets are used as core material. Exciting field and iron loss increase proportionally to plastic deformation in the case of rPeddy currents increase because plastic deformations of crystalline grains are distributed and then the flux distribution is induced. In the case of rP>20, the deterioration tend to saturate, and the increases in magnetic field and iron loss are 1000 to 1500A/m and 2 to 4W/kg. They are related to grain size, and high grade with larger grain may have lager field increase and smaller iron loss increase. Anomalous eddy current losses scarcely increase in this region. In actual motors, the plastic deformation affects iron loss increase although exciting current increases a little.

  5. Quantitative estimation on delaying of onset of corrosion of rebar in surface treated concrete using sealers

    Directory of Open Access Journals (Sweden)

    A. Sivasankar

    2013-12-01

    Full Text Available Surface treatment on the concrete surface using sealers reduces the rate of permeability of chloride and moisture through the concrete. The delaying of onset of corrosion is evaluated for surface treated and untreated concrete using electrochemical techniques. After conducting rapid chloride permeability test (RCPT, using Nernst–Plank equation, the diffusion coefficient of chloride (Deff is calculated. Substituting threshold chloride concentration of rebar (Cth from cyclic polarization test in the ficks second law, the time to initiation of corrosion (Ti is arrived. From the results it is found that the treated concrete with alkyltrialkoxy silane sealer delays the onset of corrosion by four times than that of untreated concrete.

  6. Capacitive sensor for engine oil deterioration measurement

    Science.gov (United States)

    Shinde, Harish; Bewoor, Anand

    2018-04-01

    A simple system or mechanism for engine Oil (lubricating oil) deterioration monitoring is a need. As engine oil is an important element in I C engines and it is exposed to various strains depending on the operating conditions. If it becomes contaminated with dirt and metal particles, it can become too thick or thin and loses its protective properties, leads to unwanted friction. In turn, to avoid an engine failure, the oil must be changed before it loses its protective properties, which may be harmful to engine which deteriorates vehicle performance. At the same time, changing the lubricant too early, cause inefficient use of already depleting resources, also unwanted impact on the environment and economic reasons. Hence, it will be always helpful to know the quality of the oil under use. With this objective, the research work had been undertaken to develop a simple capacitance sensor for quantification of the quality of oil under use. One of the investigated parameter to quantify oil degradation is Viscosity (as per standard testing procedure: DIN 51562-1). In this research work, an alternative method proposed which analyzing change in capacitance of oil, to quantify the quality of oil underuse and compared to a conventional standard method. The experimental results reported in this paper shows trend for the same. Engine oil of grade SAE 15W40 used for light-duty vehicle, vans and passenger cars is used for experimentation. Suggested method can form a base for further research to develop a cost-effective method for indicating the time to change in engine oil quality have been presented.

  7. Recycling of concrete

    International Nuclear Information System (INIS)

    Halaszovich, S.

    1988-01-01

    The paper reviews potentials and problems of disposal or recycling of concrete removed from nuclear installations. Due to the difficulties in determining radioactivity limits that are compatible with utilization of recycled material in practice, a method is proposed that takes into account inhalation of dusts, as occurring during the reprocessing or recycling of the concrete, for instance in road building. This method is based on the maximum permissible radioactivity uptake by inhalation of a nuclide mixture of unknown composition. (RB) [de

  8. Sulfur polymer cement concrete

    International Nuclear Information System (INIS)

    Weber, H.H.; McBee, W.C.

    1990-01-01

    Sulfur-based composite materials formulated using sulfur polymer cement (SPC) and mineral aggregates are described and compared with conventional portland cement based materials. Materials characteristics presented include mechanical strength, chemical resistance, impact resistance, moisture permeation, and linear shrinkage during placement and curing. Examples of preparation and placement of sulfur polymer cement concrete (SC) are described using commercial scale equipment. SC applications presented are focused into hostile chemical environments where severe portland cement concrete (PCC) failure has occurred

  9. ADVANCEMENTS IN CONCRETE TECHNOLOGY

    OpenAIRE

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

    2015-01-01

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

  10. An inventory model of instantaneous deteriorating items with controllable deterioration rate for time dependent demand and holding cost

    Directory of Open Access Journals (Sweden)

    Vinod Kumar Mishra

    2013-06-01

    Full Text Available Purpose: The purpose of this paper to develop an inventory model for instantaneous deteriorating items with the consideration of the facts that the deterioration rate can be controlled by using the preservation technology (PT and the holding cost & demand rate both are linear function of time which was treated as constant in most of the deteriorating inventory model. Design/methodology/approach: Developed the mathematical equation of deterministic deteriorating inventory model in which demand rate and holding cost both is linear function of time, deterioration rate is constant, backlogging rate is variable and depend on the length of the next replenishment, shortages are allowed and partially backlogged and obtain an analytical solution which optimizes the total cost of the proposed inventory model. Findings: The model can be applied for optimizing the total inventory cost of deteriorating items inventory for such business enterprises where they use the preservation technology to control the deterioration rate under other assumptions of the model. Originality/value: The inventory system for deteriorating items has been an object of study for a long time, but little is known about the effect of investing in reducing the rate of product deterioration and their significant impact in the business. The proposed model is effective as well as efficient for the business organization that uses the preservation technology to reduce the deterioration rate of the instantaneous deteriorating items of the inventory.

  11. 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%.

  12. Fracture Mechanics of Concrete

    DEFF Research Database (Denmark)

    Ulfkjær, Jens Peder

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

  13. Fibre-concrete container

    International Nuclear Information System (INIS)

    2000-01-01

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

  14. Concrete radiation shielding

    International Nuclear Information System (INIS)

    Kaplan, M.F.

    1989-01-01

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

  15. Separation of contaminated concrete

    International Nuclear Information System (INIS)

    Bakiewicz, J.L.; Reymer, A.P.S.

    1990-01-01

    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

  16. Glovebox glove deterioration in the Hanford Engineering Development Laboratory fuel fabrication facility

    International Nuclear Information System (INIS)

    Greenhalgh, W.O.; Smith, R.C.; Powell, D.L.

    1979-07-01

    Neoprene glovebox gloves have been found susceptible to periodic rapid deterioration under normal operating conditions in fuel fabrication facilities. Examinations of glove failure histories and measurements of the atmospheres in inert atmosphere dry-boxes indicated ozone at low concentrations of 100 to 500 ppB was probably the most important factor in rapid glove deterioration. Testing of a varity of new glove materials indicated that Hypalon and ethylene-propylene-diamine monomer (EDPM) gloves have greater than 30 times the longevity of neoprene in low-level ozone concentration atmospheres. comparative tests over a 30-month period have also confirmed that the two glove candidates have a significantly longer operative life. 14 figures

  17. Offshore concrete structures

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  18. 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.

  19. Experimental investigation of the relation between damage at the concrete-steel interface and initiation of reinforcement corrosion in plain and fibre reinforced concrete

    International Nuclear Information System (INIS)

    Michel, A.; Solgaard, A.O.S.; Pease, B.J.; Geiker, M.R.; Stang, H.; Olesen, J.F.

    2013-01-01

    Highlights: •Cracked plain and steel fibre reinforced concrete flexural beams were investigated. •“Instrumented rebars” provided location- and time-dependent corrosion measurements. •Interfacial condition can be used as a reliable indicator to quantify the risk of corrosion. •Simulated interfacial conditions are in very good agreement with all experimental observations. -- Abstract: Cracks in covering concrete are known to hasten initiation of steel corrosion in reinforced concrete structures. To minimise the impact of cracks on the deterioration of reinforced concrete structures, current approaches in (inter)national design codes often limit the concrete surface crack width. Recent investigations however, indicate that the concrete-reinforcement interfacial condition is a more fundamental criterion related to reinforcement corrosion. This work investigates the relation between macroscopic damage at the concrete-steel interface and corrosion initiation of reinforcement embedded in plain and fibre reinforced concrete. Comparisons of experimental and numerical results indicate a strong correlation between corrosion initiation and interfacial condition

  20. Study on Construction Technology of Municipal Road and Bridge Concrete

    Science.gov (United States)

    Tang, Fuyong

    2018-03-01

    With the continuous development of social economy and the accelerating process of urbanization, municipal road and bridge projects have also shown a trend of rapid development. Municipal road and bridge work can fully reflect the economic and cultural development level of cities and is also an important symbol of urban development. As a basic material of construction, concrete is widely used in engineering construction. This article will analyze the municipal road and bridge concrete construction technology, put forward corresponding measures.

  1. Design considerations and sustainability of self-compacting concrete

    OpenAIRE

    Grünewald, Steffen; De Schutter, Geert

    2016-01-01

    Self-compacting concrete (SCC) differs from conventional vibrated concrete (CVC) in the rheological behaviour, which is achieved by adequate mix design. The application and production requirements also pose demands on the mix design and workability. Effective production requires adequate strength control. The use of Portland Cement promotes a rapid early age strength development, but it comes with a relative high impact on the environment since decarbonation and a high energ...

  2. The deterioration of signal to noise ratio due to baseline restoration

    International Nuclear Information System (INIS)

    Henein, K.L.

    1976-02-01

    The deterioration of signal to noise ratio due to baseline restoration is theoretically studied. This study brings to the conclusion that a restorer has negligible influence on the signal to noise ratio when its time constant is ten times greater than that of the main amplifier filter, and that the rapid restorers prevail over the slow ones when the time constant of the filter is increased by at least 50% of its optimal value [fr

  3. Evaluation on effects of chloride-induced deterioration on mechanical properties of RC beams with cracking damage

    International Nuclear Information System (INIS)

    Matsuo, Toyofumi; Matsumura, Takuro; Otsuka, Taku

    2015-01-01

    This paper discusses the influence of chloride-induced deterioration on mechanical properties of aging reinforced concrete (RC) structures and the applicability of the material degradation model that takes reinforcing steel corrosion into consideration for finite element analysis. We conducted the corrosion tests under the simulated tidal environment and the flexural loading tests for the RC beams with cracking damage and initial defects. Then, the experimental results were numerically correlated to validate the devised modeling. The obtained results were summarized as follows: (a) The cracking damage in specimens caused a minor effect on the reinforcing steel corrosion in the case where the thickness of cover concrete was 40 mm and main rebars did not yield before chloride attack. On the other hand the maximum corrosion ratio of the deteriorated part became considerably larger than that of the non-cracking part in the specimens where the cover concrete were removed partially to simulate spalling by the severe corrosion. (b) Based on the test results, we derived the corrosion velocity of reinforcing steel corresponding to cracking damage degrees. (c) In FEM analyses, we showed that the above modeling can estimate the flexural strength of RC beams in consideration of the degradation in elongation performance of reinforcing steel due to corrosion. (author)

  4. Enhancement of properties of recycled coarse aggregate concrete using bacteria

    Science.gov (United States)

    Sahoo; Arakha; Sarkar; P; Jha

    2016-01-01

    Due to rapid construction, necessity for raw materials of concrete, especially coarse aggregate, tends to increase the danger of early exhaustion of the natural resources. An alternative source of raw materials would perhaps delay the advent of this early exhaustion. Recycled coarse aggregate (RCA) plays a great role as an alternative raw material that can replace the natural coarse aggregate (NCA) for concrete. Previous studies show that the properties of RCA concrete are inferior in quality compared to NCA concrete. This article attempts to study the improvement of properties of RCA concrete with the addition of bacteria named as Bacillus subtilis. The experimental investigation was carried out to evaluate the improvement of the compressive strength, capillary water absorption, and drying shrinkage of RCA concrete incorporating bacteria. The compressive strength of RCA concrete is found to be increased by about 20% when the cell concentration of B. subtilis is 106 cells/ml. The capillary water absorption as well as drying shrinkage of RCA are reduced when bacteria is incorporated. The improvement of RCA concrete is confirmed to be due to the calcium carbonate precipitation as observed from the microstructure studies carried out on it such as EDX, SEM, and XRD.

  5. Usage of Crushed Concrete Fines in Decorative Concrete

    Science.gov (United States)

    Pilipenko, Anton; Bazhenova, Sofia

    2017-10-01

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

  6. Effect of flood conditions on the deterioration of porous clay-based brick

    Science.gov (United States)

    Mol, L.; Tomor, A.

    2017-12-01

    Man-made materials represent an increasingly large proportion of geomaterials that are used to build up a rapidly expanding urbanised landscape. The deterioration of such materials is of increasing concern, in particular in light of the projected increase in storm and flood events and their associated high water levels. The effect of prolonged saturation in porous materials, man-made as well as natural, can lead to accelerated deterioration. This can be of particular concern for load-bearing structural materials, for example bridges. In this study, the effect of moisture movement has been investigated for brick masonry, as one of the most commonly used porous building materials. Saturation of brick masonry can be of particular concern for historical masonry, such as masonry arch bridges in conjunction with under increasing levels of long-term traffic loading. While flooding can lead to scour and sudden collapse of bridges, saturation can also lead to accelerated medium and long-term deterioration. A series of small-scale laboratory tests have been carried out on brick masonry to identify the effects of saturation on the material properties and changes in the rate of deterioration. Brick masonry prisms have been loaded to failure under quasi-static and long-term cyclic compression and monitored with the help of acoustic emission technique, accelerometers, linear variable differential transformers (LVDTs), permeametry and brick surface hardness measurements. Under quasi-static loading saturated samples showed significant reduction in the load capacity and increased fracture development. Under fatigue loading the number of cycles to failure reduced significantly for saturated specimens and characteristic changes in material parameters have been related to stages of fatigue deterioration. Test results indicated that increasing flood events can accelerate moisture-related deterioration in porous brick masonry.

  7. Rapid response systems.

    Science.gov (United States)

    Lyons, Patrick G; Edelson, Dana P; Churpek, Matthew M

    2018-07-01

    Rapid response systems are commonly employed by hospitals to identify and respond to deteriorating patients outside of the intensive care unit. Controversy exists about the benefits of rapid response systems. We aimed to review the current state of the rapid response literature, including evolving aspects of afferent (risk detection) and efferent (intervention) arms, outcome measurement, process improvement, and implementation. Articles written in English and published in PubMed. Rapid response systems are heterogeneous, with important differences among afferent and efferent arms. Clinically meaningful outcomes may include unexpected mortality, in-hospital cardiac arrest, length of stay, cost, and processes of care at end of life. Both positive and negative interventional studies have been published, although the two largest randomized trials involving rapid response systems - the Medical Early Response and Intervention Trial (MERIT) and the Effect of a Pediatric Early Warning System on All-Cause Mortality in Hospitalized Pediatric Patients (EPOCH) trial - did not find a mortality benefit with these systems, albeit with important limitations. Advances in monitoring technologies, risk assessment strategies, and behavioral ergonomics may offer opportunities for improvement. Rapid responses may improve some meaningful outcomes, although these findings remain controversial. These systems may also improve care for patients at the end of life. Rapid response systems are expected to continue evolving with novel developments in monitoring technologies, risk prediction informatics, and work in human factors. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Ultrasonic imaging in concrete

    International Nuclear Information System (INIS)

    Ribay, G.; Paris, O.; Rambach, J.M.

    2009-01-01

    The third and final protection barrier confining nuclear reactors is usually a concrete containment structure. Monitoring the structural integrity of these barriers is critical in ensuring the safety of nuclear power plants. The Institute for Radiological Protection and Nuclear Safety (IRSN) in France in collaboration with the French Atomic commission (CEA/LIST) has developed an ultrasonic phased-array technique capable of inspecting thick concrete walls. The non-destructive method is dedicated to detect cracks and bulk defects. Given the thickness of the structure (1.2 m) undergoing inspection and the heterogeneity of the concrete, the optimal frequency lies in the 50-300 kHz range. At these frequencies, the ultrasonic beam profiles are widespread (non-directive) with poor signal-to-noise ratio. Previous studies have shown the potential of using phased-array techniques (i.e., beam focusing and beam steering) in order to improve detection resolution and sizing accuracy. In this paper we present experimental studies performed with array up to 16 transducers working at 200 kHz. Experiments are carried out on representative concrete blocks containing artificial defects. One is a reinforced mock-up representative of the first reinforcing mesh of wall containment. Experimental results show that in spite of the reinforcement, artificial defects deep as half a meter can be detected. Reconstructed images resulting from phased array acquisitions on an artificial crack embedded in a concrete block are also presented and discussed. The presented method allows detecting oriented defects in concrete with improved signal to noise ratio and sensibility. A simulation model of the interaction of ultrasound with a heterogeneous medium like concrete is briefly commented. (authors)

  9. Tritium sorption on protective coatings for concrete

    International Nuclear Information System (INIS)

    Miller, J.M.; Senohrabek, J.A.; Allsop, P.A.

    1992-11-01

    Because of the high sorption level of tritium on unprotected concrete, a program to examine the effectiveness of various concrete coatings and sealants in reducing tritium sorption was undertaken, and various exposure conditions were examined. Coatings of epoxy, polyurethane, bituminous sealant, bituminous sealant covered with polyvinylidene chloride wrap, alkyd paint, and sodium silicate were investigated with tritium (HTO) vapor concentration, humidity and contact time being varied. An exposure to HT was also carried out, and the effect of humidity on the tritium desorption rate was investigated. The relative effectiveness of the coatings was in the order of bituminous sealant + wrap > bituminous sealant > solvent-based epoxy > 100%-solids epoxy > alkyd paint > sodium silicate. The commercially available coatings for concrete resulted in tritium sorption being reduced to less than 7% of unprotected concrete. This was improved to ∼0.1% with the use of the Saran wrap (polyvinylidene chloride). The amount of tritium sorbed was proportional to tritium concentration. The total tritium sorbed decreased with an increase in humidity. A saturation effect was observed with increasing exposure time for both the coated and unprotected samples. Under the test conditions, complete saturation was not achieved within the maximum 8-hour contact time, except for the solvent-based epoxy. The desorption rate increased with a higher-humidity air purge stream. HT desorbed more rapidly than HTO, but the amount sorbed was smaller. The experimental program showed that HTO sorption by concrete can be significantly reduced with the proper choice of coating. However, tritium sorption on concrete and proposed coatings will continue to be a concern until the effects of the various conditions that affect the adsorption and desorption of tritium are firmly established for both chronic and acute tritium release conditions. Material sorption characteristics must also be considered in

  10. Freeze-Thaw Durability of Air-Entrained Concrete

    Directory of Open Access Journals (Sweden)

    Huai-Shuai Shang

    2013-01-01

    Full Text Available One of the most damaging actions affecting concrete is the abrupt temperature change (freeze-thaw cycles. The types of deterioration of concrete structures by cyclic freeze-thaw can be largely classified into surface scaling (characterized by the weight loss and internal crack growth (characterized by the loss of dynamic modulus of elasticity. The present study explored the durability of concrete made with air-entraining agent subjected to 0, 100, 200, 300, and 400 cycles of freeze-thaw. The experimental study of C20, C25, C30, C40, and C50 air-entrained concrete specimens was completed according to “the test method of long-term and durability on ordinary concrete” GB/T 50082-2009. The dynamic modulus of elasticity and weight loss of specimens were measured after different cycles of freeze-thaw. The influence of freeze-thaw cycles on the relative dynamic modulus of elasticity and weight loss was analyzed. The findings showed that the dynamic modulus of elasticity and weight decreased as the freeze-thaw cycles were repeated. They revealed that the C30, C40, and C50 air-entrained concrete was still durable after 300 cycles of freeze-thaw according to the experimental results.

  11. Damage Detection in Railway Prestressed Concrete Sleepers using Acoustic Emission

    Science.gov (United States)

    Clark, A.; Kaewunruen, S.; Janeliukstis, R.; Papaelias, M.

    2017-10-01

    Prestressed concrete sleepers (or railroad ties) are safety-critical elements in railway tracks that distribute the wheel loads from the rails to the track support system. Over a period of time, the concrete sleepers age and deteriorate in addition to experiencing various types of static and dynamic loading conditions, which are attributable to train operations. In many cases, structural cracks can develop within the sleepers due to high intensity impact loads or due to poor track maintenance. Often, cracks of sleepers develop and present at the midspan due to excessive negative bending. These cracks can cause broken sleepers and sometimes called ‘center bound’ problem in railway lines. This paper is the world first to present an application of non-destructive acoustic emission technology for damage detection in railway concrete sleepers. It presents experimental investigations in order to detect center-bound cracks in railway prestressed concrete sleepers. Experimental laboratory testing involves three-point bending tests of four concrete sleepers. Three-point bending tests correspond to a real failure mode, when the loads are not transferred uniformly to the ballast support. It is observed that AE sensing provides an accurate means for detecting the location and magnitude of cracks in sleepers. Sensor location criticality is also highlighted in the paper to demonstrate the reliability-based damage detection of the sleepers.

  12. An Expert System for Concrete Bridge Management

    DEFF Research Database (Denmark)

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

    1997-01-01

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

  13. Reliability analysis and updating of deteriorating systems with subset simulation

    DEFF Research Database (Denmark)

    Schneider, Ronald; Thöns, Sebastian; Straub, Daniel

    2017-01-01

    An efficient approach to reliability analysis of deteriorating structural systems is presented, which considers stochastic dependence among element deterioration. Information on a deteriorating structure obtained through inspection or monitoring is included in the reliability assessment through B...... is an efficient and robust sampling-based algorithm suitable for such analyses. The approach is demonstrated in two case studies considering a steel frame structure and a Daniels system subjected to high-cycle fatigue....

  14. ANDERS: future of concrete bridge deck evaluation and rehabilitation

    Science.gov (United States)

    Gucunski, Nenad; Moon, Franklin

    2011-04-01

    The Automated Nondestructive Evaluation and Rehabilitation System (ANDERS) aims to provide a uniquely comprehensive tool that will transform the manner in which bridge decks are assessed and rehabilitated. It is going to be achieved through: 1) much higher evaluation detail and comprehensiveness of detection at an early stage deterioration, 2) comprehensive condition and structural assessment at all stages of deterioration, and 3) integrated assessment and rehabilitation that will be minimally invasive, rapid and cost effective. ANDERS is composed of four systems. that merge novel imaging and NDE techniques, together with novel intervention approaches to arrest the deterioration processes. These technologies are incorporated within a series of human-operated and robotic vehicles. To perform assessments, ANDERS will be equipped with two complimentary nondestructive approaches. The first, Multi-Modal Nondestructive Evaluation (MM-NDE) System aims to identify and characterize localized deterioration with a high degree of resolution. The second, Global Structural Assessment (GSA) System aims to capture global structural characteristics and identify any appreciable effects of deterioration on a bridge structure. Output from these two approaches will be merged through a novel Automated Structural Identification (Auto St-Id) approach that will construct, calibrate, and utilize simulation models to assess overall structural vulnerability and capacity. These three systems comprise the assessment suite of ANDERS and will directly inform the Nondestructive Rehabilitation (NDR) System. The NDR System leverages robotics for the precision and rapid delivery of novel materials capable of halting the early-stage deterioration identified.

  15. Let’s Get Concrete!

    DEFF Research Database (Denmark)

    Jones, Candace; Boxenbaum, Eva

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

  16. Studies of historic concrete

    International Nuclear Information System (INIS)

    Jull, S.P.; Lees, T.P.

    1990-01-01

    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

  17. The hydraulic capacity of deteriorating sewer systems.

    Science.gov (United States)

    Pollert, J; Ugarelli, R; Saegrov, S; Schilling, W; Di Federico, V

    2005-01-01

    Sewer and wastewater systems suffer from insufficient capacity, construction flaws and pipe deterioration. Consequences are structural failures, local floods, surface erosion and pollution of receiving waters bodies. European cities spend in the order of five billion Euro per year for wastewater network rehabilitation. This amount is estimated to increase due to network ageing. The project CARE-S (Computer Aided RE-habilitation of Sewer Networks) deals with sewer and storm water networks. The final project goal is to develop integrated software, which provides the most cost-efficient system of maintenance, repair and rehabilitation of sewer networks. Decisions on investments in rehabilitation often have to be made with uncertain information about the structural condition and the hydraulic performance of a sewer system. Because of this, decision-making involves considerable risks. This paper presents the results of research focused on the study of hydraulic effects caused by failures due to temporal decline of sewer systems. Hydraulic simulations are usually carried out by running commercial models that apply, as input, default values of parameters that strongly influence results. Using CCTV inspections information as dataset to catalogue principal types of failures affecting pipes, a 3D model was used to evaluate their hydraulic consequences. The translation of failures effects in parameters values producing the same hydraulic conditions caused by failures was carried out through the comparison of laboratory experiences and 3D simulations results. Those parameters could be the input of 1D commercial models instead of the default values commonly inserted.

  18. Early deterioration of coarse woody debris.

    Energy Technology Data Exchange (ETDEWEB)

    Tainter, Frank, H.; McMinn, James, W.

    1999-02-16

    Tainter, F.H., and J.W. McMinn. 1999. Early deterioration of coarse woody debris. In: Proc. Tenth Bien. South. Silv. Res. Conf. Shreveport, LA, February 16-18, 1999. Pp. 232-237 Abstract - Coarse woody debris (CWD) is an important structural component of southern forest ecosystems. CWD loading may be affected by different decomposition rates on sites of varying quality. Bolts of red oak and loblolly pine were placed on plots at each of three (hydric, mesic. and xerlc) sites at the Savannah River Site and sampled over a I6-week period. Major changes were in moisture content and nonstructural carbohydrate content (total carbohydrates, reducing sugars, and starch) of sapwood. Early changes in nonstructural carbohydrate levels following placement of the bolts were likely due to reallocation of these materials by sapwood parenchyma cells. These carbohydrates later formed pools increasingly metabolized by bacteria and invading fungi. Most prevalent fungi in sapwood were Ceratocysfis spp. in pine and Hypoxy/on spp. in oak. Although pine sapwood became blue stained and oak sapwood exhibited yellow soft decay with black zone lines, estimators of decay (specific gravity, sodium hydroxide solubility, and holocellulose content) were unchanged during the 16-week study period. A small effect of site was detected for starch content of sapwood of both species. Fungal biomass in sapwood of both species, as measured by ergosterol content, was detectable at week zero, increased somewhat by week three and increased significantly by week 16.

  19. Concrete and prestressing process, container made with this concrete

    International Nuclear Information System (INIS)

    Gerard, M.

    1992-01-01

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

  20. Concrete with onyx waste aggregate as aesthetically valued structural concrete

    Science.gov (United States)

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

    2017-09-01

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

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

    Science.gov (United States)

    1968-08-01

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

  2. Environmental Impact Analysis of Acidification and Eutrophication Due to Emissions from the Production of Concrete

    Directory of Open Access Journals (Sweden)

    Tae Hyoung Kim

    2016-06-01

    Full Text Available Concrete is a major material used in the construction industry that emits a large amount of substances with environmental impacts during its life cycle. Accordingly, technologies for the reduction in and assessment of the environmental impact of concrete from the perspective of a life cycle assessment (LCA must be developed. At present, the studies on LCA in relation to greenhouse gas emission from concrete are being carried out globally as a countermeasure against climate change. However, the studies on the impact of the substances emitted in the concrete production process on acidification and eutrophication are insufficient. As such, assessing only a single category of environmental impact may cause a misunderstanding about the environmental friendliness of concrete. The substances emitted in the concrete production process have an impact not only on global warming but also on acidification and eutrophication. Acidification and eutrophication are the main causes of air pollution, forest destruction, red tide phenomena, and deterioration of reinforced concrete structures. For this reason, the main substances among those emitted in the concrete production process that have an impact on acidification and eutrophication were deduced. In addition, an LCA technique through which to determine the major emissions from concrete was proposed and a case analysis was carried out. The substances among those emitted in the concrete production process that are related to eutrophication were deduced to be NOx, NH3, NH4+, COD, NO3−, and PO43−. The substances among those emitted in the concrete production process that are related to acidification, were found to be NOx, SO2, H2S, and H2SO4. The materials and energy sources among those input into the concrete production process, which have the biggest impact on acidification and eutrophication, were found to be coarse aggregate and fine aggregate.

  3. Structural Effects of Reinforced Concrete Beam Due to Corrosion

    Science.gov (United States)

    Noh, Hamidun Mohd; Idris, Nur'ain; Noor, Nurazuwa Md; Sarpin, Norliana; Zainal, Rozlin; Kasim, Narimah

    2018-03-01

    Corrosion of steel in reinforced concrete is one of the main issues among construction stakeholders. The main consequences of steel corrosion include loss of cross section of steel area, generation of expansive pressure which caused cracking of concrete, spalling and delaminating of the concrete cover. Thus, it reduces the bond strength between the steel reinforcing bar and concrete, and deteriorating the strength of the structure. The objective of this study is to investigate the structural effects of corrosion damage on the performance of reinforced concrete beam. A series of corroded reinforced concrete beam with a corrosion rate of 0%, 20% and 40% of rebar corrosion is used in parametric study to assess the influence of different level of corrosion rate to the structural performance. As a result, the used of interface element in the finite element modelling predicted the worst case of corrosion analysis since cracks is induced and generate at this surface. On the other hand, a positive linear relationship was sketched between the increase of expansive pressure and the corrosion rate. Meanwhile, the gradient of the graph is decreased with the increase of steel bar diameter. Furthermore, the analysis shows that there is a significant effect on the load bearing capacity of the structure where the higher corrosion rate generates a higher stress concentration at the mid span of the beam. This study could predict the residual strength of reinforced concrete beam under the corrosion using the finite element analysis. The experimental validation is needed on the next stage to investigate the quantitative relation between the corrosion rate and its influence on the mechanical properties.

  4. Reversal deterioration of renal function accompanied with primary hypothyrodism

    Directory of Open Access Journals (Sweden)

    Dragović Tamara

    2012-01-01

    Full Text Available Introduction. Hypothyroidism is often accompanied with decline of kidney function, or inability to maintain electrolyte balance. These changes are usually overlooked in everyday practice. Early recognition of this association eliminates unnecessary diagnostic procedures that postpone the adequate treatment. Case report. Two patients with elevated serum creatinine levels due to primary autoimmune hypothyroidism, with complete recovery of creatinine clearance after thyroid hormone substitution therapy are presented. The first patient was a young male whose laboratory tests suggested acute renal failure, and the delicate clinical presentation of reduced thyroid function. The second patient was an elderly woman with a history of a long-term signs and symptoms attributed to ageing, including the deterioration of renal function, with consequently delayed diagnosis of hypothyroidism. Conclusion. Serum thyrotropin and thyroxin levels measurement should be done in all cases of renal failure with undefined renal desease, even if the typical clinical presentation of hypothyroidism is absent. Thyroid hormone assays sholud also be performed in all patients with chronic kidney disease whose kidney function is rapidly worsening.

  5. Reversal deterioration of renal function accompanied with primary hypothyrodism.

    Science.gov (United States)

    Dragović, Tamara

    2012-02-01

    Hypothyroidism is often accompanied with decline of kidney function, or inability to maintain electrolyte balance. These changes are usually overlooked in everyday practice. Early recognition of this association eliminates unnecessary diagnostic procedures that postpone the adequate treatment. Two patients with elevated serum creatinine levels due to primary autoimmune hypothyroidism, with complete recovery of creatinine clearance after thyroid hormone substitution therapy are presented. The first patient was a young male whose laboratory tests suggested acute renal failure, and the delicate clinical presentation of reduced thyroid function. The second patient was an elderly woman with a history of a long-term signs and symptoms attributed to ageing, including the deterioration of renal function, with consequently delayed diagnosis of hypothyroidism. Serum thyrotropin and thyroxin levels measurement should be done in all cases of renal failure with undefined renal desease, even if the typical clinical presentation of hypothyroidism is absent. Thyroid hormone assays sholud also be performed in all patients with chronic kidney disease whose kidney function is rapidly worsening.

  6. Water Entrainment in Concrete

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Hansen, Per Freiesleben

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

  7. Drying of Concrete

    DEFF Research Database (Denmark)

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

    2002-01-01

    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...

  8. The effectiveness of education in the recognition and management of deteriorating patients: A systematic review.

    Science.gov (United States)

    Connell, Clifford J; Endacott, Ruth; Jackman, Jennifer A; Kiprillis, Noelleen R; Sparkes, Louise M; Cooper, Simon J

    2016-09-01

    Survival from in-hospital cardiac arrest is poor. Clinical features, including abnormal vital signs, often indicate patient deterioration prior to severe adverse events. Early warning systems and rapid response teams are commonly used to assist the health profession in the identification and management of the deteriorating patient. Education programs are widely used in the implementation of these systems. The effectiveness of the education is unknown. The aims of this study were to identify: (i) the evidence supporting educational effectiveness in the recognition and management of the deteriorating patient and (ii) outcome measures used to evaluate educational effectiveness. A mixed methods systematic review of the literature was conducted using studies published between 2002 and 2014. Included studies were assessed for quality and data were synthesized thematically, while original data are presented in tabular form. Twenty-three studies were included in the review. Most educational programs were found to be effective reporting significant positive impacts upon learners, patient outcomes and organisational systems. Outcome measures related to: i learners, for example knowledge and performance, ii systems, including activation and responses of rapid response teams, and iii patients, including patient length of stay and adverse events. All but one of the programs used blended teaching with >87% including medium to high fidelity simulation. In situ simulation was employed in two of the interventions. The median program time was eight hours. The longest program lasted 44h however one of the most educationally effective programs was based upon a 40min simulation program. Educational interventions designed to improve the recognition and management of patient deterioration can improve learner outcomes when they incorporate medium to high-fidelity simulation. High-fidelity simulation has demonstrated effectiveness when delivered in brief sessions lasting only forty minutes

  9. Use of fiber reinforced concrete for concrete pavement slab replacement.

    Science.gov (United States)

    2014-03-01

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

  10. 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 devel......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...

  11. Sprayed concrete linings

    Energy Technology Data Exchange (ETDEWEB)

    Hindle, D.

    1999-12-01

    Sprayed concrete, or shotcrete, was invented in the 1920s for preserving dinosaur skeletons and was used underground initially in coalmines for the preservation and fine proofing of timber supports. Its use as a support lining in rock tunnelling was developed in the 1950s and 60s. The article surveys equipment available from major manufacturers and suppliers of concrete spraying equipment (Aliva, Cifa, GIA, Industri, Ingersoll Rand, etc.), specialist cement and additive manufacturers (Castle, Cement, Moria Carbotech). manufacturers of lattice girders and fibre reinforcement, and manufacturers of instrumentation for tunnel linings. 5 tabs., 9 photos.

  12. 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.

  13. Structural Materials: 95. Concrete

    International Nuclear Information System (INIS)

    Naus, Dan J.

    2012-01-01

    Nuclear power plant concrete structures and their materials of construction are described, and their operating experience noted. Aging and environmental factors that can affect the durability of the concrete structures are identified. Basic components of a program to manage aging of these structures are identified and described. Application of structural reliability theory to devise uniform risk-based criteria by which existing facilities can be evaluated to achieve a desired performance level when subjected to uncertain demands and to quantify the effects of degradation is outlined. Finally, several areas are identified where additional research is desired.

  14. The use of maturity method in estimating concrete strength

    International Nuclear Information System (INIS)

    Salama, A.E.; Abd El-Baky, S.M.; Ali, E.E.; Ghanem, G.M.

    2005-01-01

    Prediction of the early age strength of concrete is essential for modernized concrete for construction as well as for manufacturing of structural parts. Safe and economic scheduling of such critical operations as form removal and re shoring, application of post-tensioning or other mechanical treatment, and in process transportation and rapid delivery of products all should be based upon a good grasp of the strength development of the concrete in use. For many years, it has been proposed that the strength of concrete can be related to a simple mathematical function of time and temperature so that strength could be assessed by calculation without mechanical testing. Such functions are used to compute what is called the m aturity o f concrete, and the computed value is believed to obtain a correlation with the strength of concrete. With its simplicity and low cost, the application of maturity concept as in situ testing method has received wide attention and found its use in engineering practice. This research work investigates the use of M aturity method' in estimating the concrete strength. An experimental program is designed to estimate the concrete strength by using the maturity method. Using different concrete mixes, with available local materials. Ordinary Portland Cement, crushed stone, silica fume, fly ash and admixtures with different contents are used . All the specimens were exposed to different curing temperatures (10, 25 and 40 degree C), in order to get a simplified expression of maturity that fits in with the influence of temperature. Mix designs and charts obtained from this research can be used as guide information for estimating concrete strength by using the maturity method

  15. Concrete-Filled Steel Tube Arch Bridges in China

    Directory of Open Access Journals (Sweden)

    Jielian Zheng

    2018-02-01

    Full Text Available In the past 20 years, great progress has been achieved in China in the construction of concrete-filled steel tube (CFST arch bridges and concrete arch bridges with a CFST skeleton. The span of these bridges has been increasing rapidly, which is rare in the history of bridge development. The large-scale construction of expressways and high-speed railways demands the development of long-span arch bridges, and advances in design and construction techniques have made it possible to construct such bridges. In the present study, the current status, development, and major innovative technologies of CFST arch bridges and concrete arch bridges with a CFST skeleton in China are elaborated. This paper covers the key construction technologies of CFST arch bridges, such as the design, manufacture, and installation of steel tube arch trusses, the preparation and pouring of in-tube concrete, and the construction of the world’s longest CFST arch bridge—the First Hejiang Yangtze River Bridge. The main construction technologies of reinforced concrete arch bridges are also presented, which include cable-stayed fastening-hanging cantilever assembly, adjusting the load by means of stay cables, surrounding the concrete for arch rib pouring, and so forth. In addition, the construction of two CFST skeleton concrete arch bridges—the Guangxi Yongning Yong River Bridge and the Yunnan–Guangxi Railway Nanpan River Bridge—is discussed. CFST arch bridges in China have already gained a world-leading position; with the continuous innovation of key technologies, China will become the new leader in promoting the development of arch bridges. Keywords: Concrete-filled steel tube (CFST arch bridge, Steel-reinforced concrete arch bridge, Cable-stayed fastening-hanging cantilever assembly, Vacuum-assisted pouring in-tube concrete, Adjusting load by stay cables

  16. Permeability of Concrete with Recycled Concrete Aggregate and Pozzolanic Materials under Stress.

    Science.gov (United States)

    Wang, Hailong; Sun, Xiaoyan; Wang, Junjie; Monteiro, Paulo J M

    2016-03-30

    The research reported herein studied the permeability of concrete containing recycled-concrete aggregate (RA), superfine phosphorous slag (PHS), and ground granulated blast-furnace slag (GGBS) with and without stress. Test results showed that the chloride diffusion coefficient of RA concrete (RAC) without external loads decreased with time, and the permeability of RAC is much lower than that of the reference concrete due to the on-going hydration and the pozzolanic reaction provided by the PHS and GGBS additives in the RAC mixture. The permeability of chloride under flexural load is much more sensitive than that under compressive load due to the differences in porosity and cracking pattern. At low compressive stress levels, the permeability of chloride decreased by the closing of pores and microcracks within RAC specimens. However, in a relatively short time the chloride diffusion coefficient and the chloride content increased rapidly with the increase of compressive stress when it exceeded a threshold stress level of approximate 35% of the ultimate compressive strength. Under flexural stress, the chloride transport capability increased with the increase of stress level and time. At high compressive and flexural stress levels, creep had a significant effect on the permeability of chloride in the RAC specimens due to the damage from the nucleation and propagation of microcracks over time. It is apparent that mortar cracking has more of a significant effect on the chloride transport in concrete than cracking in the interfacial transition zone (ITZ).

  17. Modeling reinforced concrete durability : [summary].

    Science.gov (United States)

    2014-06-01

    Many Florida bridges are built of steel-reinforced concrete. Floridas humid and marine : environments subject steel in these structures : to corrosion once water and salt penetrate the : concrete and contact the steel. Corroded steel : takes up mo...

  18. Advance Organizers: Concret Versus Abstract.

    Science.gov (United States)

    Corkill, Alice J.; And Others

    1988-01-01

    Two experiments examined the relative effects of concrete and abstract advance organizers on students' memory for subsequent prose. Results of the experiments are discussed in terms of the memorability, familiarity, and visualizability of concrete and abstract verbal materials. (JD)

  19. The effect of measuring procedure on the apparent rheological properties of self-compacting concrete

    DEFF Research Database (Denmark)

    Geiker, Mette Rica; Bradl, M.; Thrane, L.N.

    2002-01-01

    Torque versus time during testing of the rheological properties of fresh concrete has been investigated. The testing was performed in a BML viscometer and on a self-compacting concrete (w/c = 0.45, 70% rapid hardening Portland cement, 3% silica fume, 27% fly ash, third generation superplasticizer......, lack of steady state may explain the apparent shear-thickening behaviour of self-compacting concrete reported elsewhere. (C) 2002 Elsevier Science Ltd. All rights reserved....

  20. Multiscale Concrete Modeling of Aging Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Hammi, Yousseff [Mississippi State Univ., Mississippi State, MS (United States); Gullett, Philipp [Mississippi State Univ., Mississippi State, MS (United States); Horstemeyer, Mark F. [Mississippi State Univ., Mississippi State, MS (United States)

    2015-07-31

    In this work a numerical finite element framework is implemented to enable the integration of coupled multiscale and multiphysics transport processes. A User Element subroutine (UEL) in Abaqus is used to simultaneously solve stress equilibrium, heat conduction, and multiple diffusion equations for 2D and 3D linear and quadratic elements. Transport processes in concrete structures and their degradation mechanisms are presented along with the discretization of the governing equations. The multiphysics modeling framework is theoretically extended to the linear elastic fracture mechanics (LEFM) by introducing the eXtended Finite Element Method (XFEM) and based on the XFEM user element implementation of Giner et al. [2009]. A damage model that takes into account the damage contribution from the different degradation mechanisms is theoretically developed. The total contribution of damage is forwarded to a Multi-Stage Fatigue (MSF) model to enable the assessment of the fatigue life and the deterioration of reinforced concrete structures in a nuclear power plant. Finally, two examples are presented to illustrate the developed multiphysics user element implementation and the XFEM implementation of Giner et al. [2009].

  1. Applications of Foamed Lightweight Concrete

    Directory of Open Access Journals (Sweden)

    Mohd Sari Kamarul Aini

    2017-01-01

    Full Text Available Application of foamed concrete is increasing at present due to high demand on foamed concrete structures with good mechanical and physical properties. This paper discusses on the use of basic raw materials, their characteristics, production process, and their application in foamed lightweight concrete with densities between 300 kg/m3 and 1800 kg/m3. It also discusses the factors that influence the strengths and weaknesses of foamed concrete based on studies that were conducted previously.

  2. TEXTILE TECHNOLOGIES IN CONCRETE ENVIRONMENTS."

    OpenAIRE

    Morrow, Ruth; Belford, Patricia

    2007-01-01

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

  3. Light Water Reactor Sustainability Program: survey of models for concrete degradation

    International Nuclear Information System (INIS)

    2014-01-01

    Concrete has been used in the construction of nuclear facilities because of two primary properties: its structural strength and its ability to shield radiation. Concrete structures have been known to last for hundreds of years, but they are also known to deteriorate in very short periods of time under adverse conditions. The use of concrete in nuclear facilities for containment and shielding of radiation and radioactive materials has made its performance crucial for the safe operation of the facility. The goal of this report is to review and document the main aging mechanisms of concern for concrete structures in nuclear power plants (NPPs) and the models used in simulations of concrete aging and structural response of degraded concrete structures. This is in preparation for future work to develop and apply models for aging processes and response of aged NPP concrete structures in the Grizzly code. To that end, this report also provides recommendations for developing more robust predictive models for aging effects of performance of concrete.

  4. Concern With Environmental Deterioration and Attitudes Toward Population Limitation

    Science.gov (United States)

    Barnett, Larry D.

    1970-01-01

    Analysis of Gallup Poll data of Junuary 1969 reveals weak association between concern about environmental deterioration and the recognition of need for eventual limitation of human population. Suggests that to increase favorable attitudes to population control, role of overpopulation in causing environmental deterioration needs to be presented to…

  5. 40 CFR 52.683 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.683 Section 52.683 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... deterioration of air quality. (a) The State of Idaho Rules for Control of Air Pollution in Idaho, specifically... the Clean Air Act for preventing significant deterioration of air quality. (b) The requirements of...

  6. 40 CFR 52.1436 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Significant deterioration of air quality. 52.1436 Section 52.1436 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. The requirements of sections 160 through 165 of the Clean Air Act...

  7. 40 CFR 52.2131 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Significant deterioration of air quality. 52.2131 Section 52.2131 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a)-(b) [Reserved] (c) All applications and other information...

  8. 40 CFR 52.884 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Significant deterioration of air quality. 52.884 Section 52.884 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... deterioration of air quality. (a) The requirements of section 160 through 165 of the Clean Air Act, as amended...

  9. 40 CFR 52.931 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.931 Section 52.931 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... deterioration of air quality. (a) Regulations for preventing significant deterioration of air quality. The..., the Kentucky Division for Air Quality has determined that the application complies with the applicable...

  10. 40 CFR 52.270 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.270 Section 52.270 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... deterioration of air quality. (a) With the exception of the areas listed in paragraph (b) of this section: (1... plan does not include approvable procedures for preventing the significant deterioration of air quality...

  11. 40 CFR 52.144 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.144 Section 52.144 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Act are not met... lands does not include approvable procedures for preventing the significant deterioration of air quality...

  12. 40 CFR 52.2380 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Significant deterioration of air quality. 52.2380 Section 52.2380 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. The program to review the construction and operation of new and...

  13. 40 CFR 52.382 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Significant deterioration of air quality. 52.382 Section 52.382 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air Act are not met...

  14. 40 CFR 52.343 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.343 Section 52.343 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air Act are not met for the following categories of sources for preventing the significant deterioration of air quality...

  15. 40 CFR 52.833 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.833 Section 52.833 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air Act are met... for preventing significant deterioration of air quality. The provisions of § 52.21 except paragraph (a...

  16. 40 CFR 52.1116 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.1116 Section 52.1116 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air... deterioration of air quality. (b) The following provisions of 40 CFR 52.21 are hereby incorporated and made a...

  17. 40 CFR 52.2581 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.2581 Section 52.2581 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a)-(c) [Reserved] (d) The requirements of sections 160 through 165... provisions for prevention of significant deterioration of air quality at 40 CFR 52.21 are applicable to the...

  18. 40 CFR 52.738 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.738 Section 52.738 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air Act are not met... air quality. (b) Regulations for preventing significant deterioration of air quality. The provisions...

  19. 40 CFR 52.96 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.96 Section 52.96 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... deterioration of air quality. (a) The State of Alaska Department of Environmental Conservation Air Quality... deterioration of air quality. (b) The requirements of sections 160 through 165 of the Clean Air Act are not met...

  20. 40 CFR 52.986 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.986 Section 52.986 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... deterioration of air quality. (a) The plan submitted by the Governor of Louisiana on August 14, 1984 (as adopted... preventing significant deterioration of air quality. (b) The requirements of sections 160 through 165 of the...

  1. 40 CFR 52.793 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.793 Section 52.793 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air Act are not met... air quality. (b) Regulations for preventing significant deterioration of air quality. The provisions...

  2. 40 CFR 52.181 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Significant deterioration of air quality. 52.181 Section 52.181 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... deterioration of air quality. (a) The plan submitted by the Governor of Arkansas as follows: (1) April 23, 1981...

  3. 40 CFR 52.1485 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.1485 Section 52.1485 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air... include approvable procedures for preventing the significant deterioration of air quality. (b) Regulation...

  4. 40 CFR 52.2346 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.2346 Section 52.2346 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The Utah plan, as submitted, is approved as meeting the... construct on Indian Reservations. (b) Regulation for prevention of significant deterioration of air quality...

  5. 40 CFR 52.1987 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.1987 Section 52.1987 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The Oregon Department of Environmental Quality rules for the prevention of significant deterioration of air quality (provisions of OAR chapter 340, Divisions 200, 202...

  6. 40 CFR 52.581 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Significant deterioration of air quality. 52.581 Section 52.581 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... deterioration of air quality. (a) All applications and other information required pursuant to § 52.21 of this...

  7. 40 CFR 52.2303 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.2303 Section 52.2303 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The plan submitted by Texas is approved as meeting the requirements of part C, Clean Air Act for preventing significant deterioration of air quality. The plan...

  8. 40 CFR 52.2083 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Significant deterioration of air quality. 52.2083 Section 52.2083 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The Rhode Island plan, as submitted, is approved as meeting the...

  9. 40 CFR 52.1280 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Significant deterioration of air quality. 52.1280 Section 52.1280 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) All applications and other information required pursuant to § 52...

  10. 40 CFR 52.1029 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Significant deterioration of air quality. 52.1029 Section 52.1029 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. The program to review operation and construction of new and modified...

  11. 40 CFR 52.432 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.432 Section 52.432 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air Act are not met... air quality. (b) Regulation for preventing significant deterioration of air quality. The provisions of...

  12. 40 CFR 52.1529 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Significant deterioration of air quality. 52.1529 Section 52.1529 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. New Hampshire's Part Env-A 623, “Requirements for Prevention of...

  13. 40 CFR 52.2178 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.2178 Section 52.2178 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a) The South Dakota plan, as submitted, is approved as meeting the... on Indian reservations; (b) Regulations for preventing significant deterioration of air quality. The...

  14. 40 CFR 52.632 - Significant deterioration of air quality.

    Science.gov (United States)

    2010-07-01

    ... quality. 52.632 Section 52.632 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... deterioration of air quality. (a) The requirements of sections 160 through 165 of the Clean Air Act are not met... air quality. (b) Regulations for preventing significant deterioration of air quality. The provisions...

  15. Review of inventory systems with deterioration since 2001

    NARCIS (Netherlands)

    Bakker, M.; Riezebos, J.; Teunter, R.H.

    2012-01-01

    This paper presents an up-to-date review of the advances made in the field of inventory control of perishable items (deteriorating inventory). The last extensive review on this topic dates back to 2001 (Goyal S.K. and Giri B.C., Recent trends in modeling of deteriorating inventory, European Journal

  16. Transport processes in partially saturate concrete: Testing and liquid properties

    Science.gov (United States)

    Villani, Chiara

    properties and pore structure information as inputs. Concrete exposed to deicing salts resulted to have a reduced gas transport due to the higher degree of saturation (DOS). The higher DOS is believed to contribute to the premature deterioration observed in concrete pavements exposed to deicing salts. Moisture diffusion and moisture profiles in concrete are known to directly relate with the stresses generated during shrinkage and creep mechanisms. The alteration due to the presence of shrinkage reducing admixtures on drying was also investigated in this work. Liquid properties were used to predict the diffusion coefficient in presence of SRA. Moisture profiles obtained using Fick's second law for diffusion were compared to relative humidity profiles measured on concrete slabs. Results confirm that a qualitative prediction of drying in concrete elements is realistic when using this type of approach.

  17. Constitutive model for reinforced concrete

    NARCIS (Netherlands)

    Feenstra, P.H.; Borst, de R.

    1995-01-01

    A numerical model is proposed for reinforced-concrete behavior that combines the commonly accepted ideas from modeling plain concrete, reinforcement, and interaction behavior in a consistent manner. The behavior of plain concrete is govern by fracture-energy-level-based formulation both in tension

  18. Porous Concrete and Its Application

    Directory of Open Access Journals (Sweden)

    V. V. Opekunov

    2005-01-01

    Full Text Available Some aspects of resource saving problem in the process of mass construction and operation of heated construction installations are considered in the paper. A special attention is paid to necessary application of porous concrete products in the process of the housing construction. The preference is given to the products made of autoclave cellular concrete and cement hydrophobisized cement perlite concrete.

  19. Concrete produced with recycled aggregates

    Directory of Open Access Journals (Sweden)

    J. J. L. Tenório

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

  20. Structural Concrete, Science into Practice

    NARCIS (Netherlands)

    Bruggeling, A.S.G.

    1987-01-01

    There is a need for a more rational and unified approach to all types of concrete structure, reinforced of prestressed. The first chapter explains in a historical review why the approach of reinforced concrete and that of prestressed concrete have hitherto been very different. In outlining the

  1. Acute functional deterioration in a child with cerebral palsy.

    LENUS (Irish Health Repository)

    Smyth, Elizabeth

    2012-01-01

    We describe a case of acute functional deterioration in a 13-year-old girl with severe spastic diplegia (GMFCS III) and a new diagnosis of diffuse intrinsic pontine glioma (DIPG). She presented with acute deterioration in mobility and motor function over 1 month, which was associated with dysarthria, dysphagia and behavioural change. Her mother had noticed subtle functional deterioration over the 2 months prior to this. Her physiotherapist who was concerned about her acute functional deterioration referred her for emergency review. Neurological imaging revealed a diffuse pontine lesion consistent with DIPG. She was subsequently referred to oncology. She deteriorated further, clinically, over the next few days and following discussion with the team; her family opted for palliative treatment, given the poor prognosis associated with DIPG.

  2. Forterra Concrete Products, Inc.

    Science.gov (United States)

    The EPA is providing notice of a proposed Administrative Penalty Assessment against Forterra Concrete Products, Inc., a business located at 511 E. John Carpenter Freeway, Irving, TX, 75062, for alleged violations at its facility located at 23600 W. 40th St

  3. 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...

  4. Anisotropic Concrete Compressive Strength

    DEFF Research Database (Denmark)

    Gustenhoff Hansen, Søren; Jørgensen, Henrik Brøner; Hoang, Linh Cao

    2017-01-01

    When the load carrying capacity of existing concrete structures is (re-)assessed it is often based on compressive strength of cores drilled out from the structure. Existing studies show that the core compressive strength is anisotropic; i.e. it depends on whether the cores are drilled parallel...

  5. 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...

  6. Hydrophobic treatment of concrete

    NARCIS (Netherlands)

    Vries, J. de; Polder, R.B.

    1996-01-01

    As part of the maintenance policy of the Dutch Ministry of Transport, Civil Engineering Division, hydrophobic treatment of concrete was considered as an additional protective measure against penetration of aggressive substances, for instance deicing salts in bridge decks. A set of tests was designed

  7. Concrete longevity overview

    International Nuclear Information System (INIS)

    Chang, W.; Morreale, B.

    1991-01-01

    A number of compact host states and unaffiliated states are currently selecting appropriate disposal technology and construction materials for their planned low-level radioactive waste (LLW) disposal facilities. Concrete is one of the candidate materials under consideration for the construction of LLW disposal facilities because of its strength, durability, abundant availability, and relatively low cost. The LLW disposal facilities must maintain intruder barrier integrity for up to 500 years, without active maintenance after the first 100 years. The ability of concrete to survive for such a long time as a construction material is a critical issue. This report provides a basic understanding of the composition and workings of concrete as a structural material in LLW disposal facilities and a description of degradation factors and state-of-the-art mitigative measures available to preserve the durability and longevity of concrete. Neither the paper nor the report is intended to be a design guidance document, and neither addresses using cement as a waste solidification agent. 5 refs., 1 tab

  8. Fracture Mechanics of Concrete

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    the international workshop on concrete fracture, organised by A Carpinteri, at Torino ... The next question is how to bring the size effect into codes of practice on the ... analysis of the recent collapse of the World Trade Center in New York by Z P ...

  9. Contaminated soil concrete blocks

    NARCIS (Netherlands)

    de Korte, A.C.J.; Brouwers, Jos; 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

  10. Electrical pulses protect concrete

    NARCIS (Netherlands)

    Koleva, D.; Fraaij, A.; 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

  11. CONCRETE REACTOR CONTAINMENT

    Energy Technology Data Exchange (ETDEWEB)

    Lumb, Ralph F.; Hall, William F.; Fruchtbaum, Jacob

    1963-06-15

    The results of various leak-rate tests demonstrate the practicality of concrete as primary containment for the maximum credible accident for a research reactor employing plate-type fuel and having a power in excess of one megawatt. Leak-test time was shortened substantially by measuring the relaxation time for overpressure decay, which is a function of leak rate. (auth)

  12. Electroosmotic decontamination of concrete

    International Nuclear Information System (INIS)

    Bostick, W.D.; Bush, S.A.; Marsh, G.C.; Henson, H.M.; Box, W.D.; Morgan, I.L.

    1993-03-01

    A method is described for the electroosmotic decontamination of concrete surfaces, in which an electrical field is used to induce migration of ionic contaminants from porous concrete into an electrolyte solution that may be disposed of as a low-level liquid radioactive waste (LLRW); alternately, the contaminants from the solution can be sorbed onto anion exchange media in order to prevent contaminant buildup in the solution and to minimize the amount of LLRW generated. We have confirmed the removal of uranium (and infer the removal of 99 Tc) from previously contaminated concrete surfaces. In a typical experimental configuration, a stainless steel mesh is placed in an electrolyte solution contained within a diked cell to serve as the negative electrode (cathode) and contaminant collection medium, respectively, and an existing metal penetration (e.g., piping, conduit, or rebar reinforcement within the concrete surface) serves as the positive electrode (anode) to complete the cell. Typically we have achieved 70 to >90% reductions in surface activity by applying 2 )

  13. Polyester polymer concrete overlay.

    Science.gov (United States)

    2013-01-01

    Polyester polymer concrete (PPC) was used in a trial application on a section of pavement that suffers from extensive studded tire wear. The purpose of the trial section is to determine if PPC is a possible repair strategy for this type of pavement d...

  14. Concrete. Connecting Creative Technologists

    NARCIS (Netherlands)

    Bakker, T.P.; Huijboom, N.M.; Koops, R.; Kotterink, B.; Nieuwenhuis, O.A.; Seiffert, L.; Siem, R.; Zee, F.A. van der

    2015-01-01

    Kruisbestuiving tussen de creatieve en high-tech sector biedt enorme kansen, bijvoorbeeld op het gebied van Smart Industry. Desondanks blijven deze kansen in de praktijk vaak onderbenut. In het project 'CONCRETE' heeft TNO op basis van een aantal case studies onderzocht welke succesfactoren tot een

  15. Delirium and high fever are associated with subacute motor deterioration in Parkinson disease: a nested case-control study.

    Directory of Open Access Journals (Sweden)

    Atsushi Umemura

    Full Text Available BACKGROUND: In Parkinson disease (PD, systemic inflammation caused by respiratory infections such as pneumonia frequently occurs, often resulting in delirium in the advanced stages of this disease. Delirium can lead to cognitive and functional decline, institutionalization, and mortality, especially in the elderly. Inflammation causes rapid worsening of PD motor symptoms and signs, sometimes irreversibly in some, but not all, patients. PURPOSE: To identify factors associated with subacute motor deterioration in PD patients with systemic inflammation. METHODS: The association of clinical factors with subacute motor deterioration was analyzed by a case-control study. Subacute motor deterioration was defined as sustained worsening by one or more modified Hoehn and Yahr (H-Y stages. Using multivariable logistic regression incorporating baseline characteristics (age, sex, PD duration, modified H-Y stage, dementia, and psychosis history and statistically selected possible predictors (peak body temperature, duration of leukocytosis, and presence of delirium, the odds ratios for these factors were estimated as relative risks. RESULTS: Of 80 PD patients with systemic inflammation, 26 with associated subacute motor deterioration were designated as cases and the remainder as controls. In the 26 cases, 6 months after its onset the motor deterioration had persisted in 19 patients and resolved in four (three were lost for follow-up. Multivariable logistic regression analysis showed that delirium and body temperature are significantly associated with motor deterioration after systemic inflammation (P = 0.001 for delirium and P = 0.026 for body temperature, the adjusted odds ratios being 15.89 (95% confidence interval [CI]: 3.23-78.14 and 2.78 (95% CI: 1.13-6.83, respectively. CONCLUSIONS: In patients with PD and systemic inflammation, delirium and high body temperature are strong risk factors for subsequent subacute motor deterioration and such deterioration

  16. Effects of gamma irradiation on deteriorated paper

    Science.gov (United States)

    Bicchieri, Marina; Monti, Michela; Piantanida, Giovanna; Sodo, Armida

    2016-08-01

    Even though gamma radiation application, also at the minimum dosage required for disinfection, causes depolymerization and degradation of the paper substrate, recently published papers seemed, instead, to suggest that γ-rays application could be envisaged in some conditions for Cultural Heritage original documents and books. In some of the published papers, the possible application of γ-rays was evaluated mainly by using mechanical tests that scarcely reflect the chemical modifications induced in the cellulosic support. In the present article the effect of low dosage γ-irradiation on cellulosic substrates was studied and monitored applying different techniques: colorimetry, spectroscopic measurements, carbonyl content and average viscometric degree of polymerization. Two different papers were investigated, a non-sized, non-filled cotton paper, and a commercial permanent paper. To simulate a real deteriorated document, which could need γ-rays irradiation, some samples were submitted to a hydrolysis treatment. We developed a treatment based on the exposition of paper to hydrochloric acid vapors, avoiding any contact of the samples with water. This method induces a degradation similar to that observed on original documents. The samples were then irradiated with 3 kGy γ-rays at a 5258 Gy/h rate. The aforementioned analyses were performed on the samples just irradiated and after artificial ageing. All tests showed negative effects of gamma irradiation on paper. Non-irradiated paper preserves better its appearance and chemical properties both in the short term and after ageing, while the irradiated samples show appreciable color change and higher oxidation extent. Since the Istituto centrale restauro e conservazione patrimonio archivistico e librario is responsible for the choice of all restoration treatments that could be applied on library and archival materials under the protection of the Italian State (http://www.icpal.beniculturali.it/allegati/DM-7

  17. Sensitivity Analysis of Corrosion Rate Prediction Models Utilized for Reinforced Concrete Affected by Chloride

    Science.gov (United States)

    Siamphukdee, Kanjana; Collins, Frank; Zou, Roger

    2013-06-01

    Chloride-induced reinforcement corrosion is one of the major causes of premature deterioration in reinforced concrete (RC) structures. Given the high maintenance and replacement costs, accurate modeling of RC deterioration is indispensable for ensuring the optimal allocation of limited economic resources. Since corrosion rate is one of the major factors influencing the rate of deterioration, many predictive models exist. However, because the existing models use very different sets of input parameters, the choice of model for RC deterioration is made difficult. Although the factors affecting corrosion rate are frequently reported in the literature, there is no published quantitative study on the sensitivity of predicted corrosion rate to the various input parameters. This paper presents the results of the sensitivity analysis of the input parameters for nine selected corrosion rate prediction models. Three different methods of analysis are used to determine and compare the sensitivity of corrosion rate to various input parameters: (i) univariate regression analysis, (ii) multivariate regression analysis, and (iii) sensitivity index. The results from the analysis have quantitatively verified that the corrosion rate of steel reinforcement bars in RC structures is highly sensitive to corrosion duration time, concrete resistivity, and concrete chloride content. These important findings establish that future empirical models for predicting corrosion rate of RC should carefully consider and incorporate these input parameters.

  18. Vectors of Defects in Reinforced Concrete Structures in Onshore Oil and Gas Process Plants

    Directory of Open Access Journals (Sweden)

    Dabo Baba Hammad

    2018-01-01

    Full Text Available There is a global outcry over the speedy deterioration of structures in oil and gas facilities. While marine environment is considered the leading factor in the deterioration of offshore structures, there is no single factor considered as the main cause of the problem in onshore structures. Therefore, the aim of this paper is to present the result of global survey on the major factors causing the deterioration of concrete structures in onshore oil and gas facilities. To realize the objectives of the paper, an e-questionnaire was administered through two International LinkedIn groups with a membership mainly dominated by experts in onshore oil and gas facilities. 159 respondents completed the questionnaires, and the reliability of the responses was calculated to be 0.950 which is considered excellent. Relative importance index was used in ranking the factors, and it was observed that environmental factors ranked as the dominant factors causing the deterioration of concrete structures in onshore process plants. Another important finding in the study is the role that experience plays on the perception of experts on the causes of defects on concrete structures.

  19. Sensor Systems for Corrosion Monitoring in Concrete Structures

    Directory of Open Access Journals (Sweden)

    K.Kumar

    2006-05-01

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

  20. Resistance of biofilm-covered mortars to microbiologically influenced deterioration simulated by sulfuric acid exposure

    Energy Technology Data Exchange (ETDEWEB)

    Soleimani, Sahar, E-mail: ssoleima@connect.carleton.ca; Isgor, O. Burkan, E-mail: burkan_isgor@carleton.ca; Ormeci, Banu, E-mail: banu_ormeci@carleton.ca

    2013-11-15

    Following the reported success of biofilm applications on metal surfaces to inhibit microbiologically influenced corrosion, effectiveness and sustainability of E. coli DH5α biofilm on mortar surface to prevent microbiologically influenced concrete deterioration (MICD) are investigated. Experiments simulating microbial attack were carried out by exposing incrementally biofilm-covered mortar specimens to sulfuric acid solutions with pH ranging from 3 to 6. Results showed that calcium concentration in control reactors without biofilm was 23–47% higher than the reactors with biofilm-covered mortar. Formation of amorphous silica gel as an indication of early stages of acid attack was observed only on the control mortar specimens without biofilm. During acidification, the biofilm continued to grow and its thickness almost doubled from ∼ 30 μm before acidification to ∼ 60 μm after acidification. These results demonstrated that E. coli DH5α biofilm was able to provide a protective and sustainable barrier on mortar surfaces against medium to strong sulfuric acid attack. -- Highlights: •Effectiveness of E.coli DH5α biofilm to prevent MICD was studied. •Conditions that lead to MICD were simulated by chemical acidification. •Biofilm-covered mortar specimens were exposed to sulfuric acid solutions. •The presence of biofilm helped reduce the chemically-induced mortar deterioration. •Biofilm remained alive and continued to grow during the acidification process.

  1. Resistance of biofilm-covered mortars to microbiologically influenced deterioration simulated by sulfuric acid exposure

    International Nuclear Information System (INIS)

    Soleimani, Sahar; Isgor, O. Burkan; Ormeci, Banu

    2013-01-01

    Following the reported success of biofilm applications on metal surfaces to inhibit microbiologically influenced corrosion, effectiveness and sustainability of E. coli DH5α biofilm on mortar surface to prevent microbiologically influenced concrete deterioration (MICD) are investigated. Experiments simulating microbial attack were carried out by exposing incrementally biofilm-covered mortar specimens to sulfuric acid solutions with pH ranging from 3 to 6. Results showed that calcium concentration in control reactors without biofilm was 23–47% higher than the reactors with biofilm-covered mortar. Formation of amorphous silica gel as an indication of early stages of acid attack was observed only on the control mortar specimens without biofilm. During acidification, the biofilm continued to grow and its thickness almost doubled from ∼ 30 μm before acidification to ∼ 60 μm after acidification. These results demonstrated that E. coli DH5α biofilm was able to provide a protective and sustainable barrier on mortar surfaces against medium to strong sulfuric acid attack. -- Highlights: •Effectiveness of E.coli DH5α biofilm to prevent MICD was studied. •Conditions that lead to MICD were simulated by chemical acidification. •Biofilm-covered mortar specimens were exposed to sulfuric acid solutions. •The presence of biofilm helped reduce the chemically-induced mortar deterioration. •Biofilm remained alive and continued to grow during the acidification process

  2. 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...

  3. Early Property Development in Concrete

    DEFF Research Database (Denmark)

    Normann, Gitte; Munch-Petersen, Christian

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

  4. Estimating Durability of Reinforced Concrete

    Science.gov (United States)

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

    2017-11-01

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

  5. Mathematical modeling for corrosion environment estimation based on concrete resistivity measurement directly above reinforcement

    International Nuclear Information System (INIS)

    Lim, Young-Chul; Lee, Han-Seung; Noguchi, Takafumi

    2009-01-01

    This study aims to formulate a resistivity model whereby the concrete resistivity expressing the environment of steel reinforcement can be directly estimated and evaluated based on measurement immediately above reinforcement as a method of evaluating corrosion deterioration in reinforced concrete structures. It also aims to provide a theoretical ground for the feasibility of durability evaluation by electric non-destructive techniques with no need for chipping of cover concrete. This Resistivity Estimation Model (REM), which is a mathematical model using the mirror method, combines conventional four-electrode measurement of resistivity with geometric parameters including cover depth, bar diameter, and electrode intervals. This model was verified by estimation using this model at areas directly above reinforcement and resistivity measurement at areas unaffected by reinforcement in regard to the assessment of the concrete resistivity. Both results strongly correlated, proving the validity of this model. It is expected to be applicable to laboratory study and field diagnosis regarding reinforcement corrosion. (author)

  6. Effect of hot-dry environment on fiber-reinforced self-compacting concrete

    Science.gov (United States)

    Tioua, Tahar; Kriker, Abdelouahed; Salhi, Aimad; Barluenga, Gonzalo

    2016-07-01

    Drying shrinkage can be a major reason for the deterioration of concrete structures. Variation in ambient temperature and relative humidity cause changes in the properties of hardened concrete which can affect their mechanical and drying shrinkage characteristics. The present study investigated mechanical strength and particularly drying shrinkage properties of self-compacting concretes (SCC) reinforced with date palm fiber exposed to hot and dry environment. In this study a total of nine different fibers reinforced self compacting concrete (FRSCC) mixtures and one mixture without fiber were prepared. The volume fraction and the length of fibers reinforcement were 0.1-0.2-0.3% and 10-20-30 mm. It was observed that drying shrinkage lessened with adding low volumetric fraction and short length of fibers in curing condition (T = 20 °C and RH = 50 ± 5 %), but increased in hot and dry environment.

  7. An historical examination of concrete

    International Nuclear Information System (INIS)

    Mallinson, L.G.

    1986-03-01

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

  8. 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.

  9. Concrete as secondary containment for interior wall embedded waste lines

    International Nuclear Information System (INIS)

    Porter, C.L.

    1993-01-01

    Throughout the Department of Energy (DOE) complex are numerous facilities that handle hazardous waste solutions. Secondary containment of tank systems and their ancillary piping is a major concern for existing facilities. The Idaho Division of Environmental Quality was petitioned in 1990 for an Equivalent Device determination regarding secondary containment of waste lines embedded in interior concrete walls. The petition was granted, however it expires in 1996. To address the secondary containment issue, additional studies were undertaken. One study verified the hypothesis that an interior wall pipe leak would follow the path of least resistance through the naturally occurring void found below a rigidly supported pipe and pass into an adjacent room where detection could occur, before any significant deterioration of the concrete takes place. Other tests demonstrated that with acidic waste solutions rebar and cold joints are not an accelerated path to the environment. The results from these latest studies confirm that the subject configuration meets all the requirements of secondary containment

  10. Managing concrete bridges: Methods for reducing costs and user inconveniences

    DEFF Research Database (Denmark)

    Goltermann, Per

    2005-01-01

    The paper presents experiences from modern bridge maintenance management, which has been forced to develop new and cost-efficient approaches in order to cope with the increase in overall deterioration of the aging bridge stock, the growing requirements to accessibility and the decreasing budgets...... situations often postpone or reduce the repair and rehabilitation activities required in critical parts of the structure. The paper will present some cases, where these approaches have been used on existing concrete bridges and explain how these experiences can be applied on other types of structures...

  11. Damaged Concrete Viaduct in an Italian Highway: Concrete Characterization and Possible Strengthening Techniques by FRP Applications in Comparison

    Science.gov (United States)

    Tittarelli, Francesca; Ruello, Maria Letizia; Capuani, Domenico; Aprile, Alessandra

    2017-10-01

    The “Fornello” viaduct in the Italian Orte-Ravenna highway (E45) is seriously damaged. In this paper, the concrete of the reinforced slab has been widely characterized to evaluate the level of damage and to identify the causes of degradation. No-destructive tests, as those based on ultrasonic waves, as well as chemical, physical and mechanical destructive tests have been carried out on specimens drawn from deteriorated and not deteriorated zones of the R/C bridge decks. Into the slab thickness, the concentration distribution of main anions has been quantified by ion chromatography. Porosimetry tests have been carried out to detect the resistance to freeze-thaw cycles of cement paste. Possible strengthening techniques by FRP applications have been compared.

  12. A study on the effect of crack in concrete structure in the point of radiation shielding

    International Nuclear Information System (INIS)

    Lee, Chang-Min; Lee, Yoon-Hee; Lee, Kun-Jai; Cho, Cheon-Hyung; Choi, Byung-Il; Lee, Heung-Young

    2005-01-01

    The saturation of South Korea's at-reactor (AR) spent fuel storage pools has created a necessity for additional spent fuel storage capacity. Because the South Korean government has a plan to increase the number of nuclear power plants to 27 units by 2016, the increase of spent nuclear fuel generation will be accelerated. Because there is no concrete plan for spent unclear fuel permanent disposal, the Korea hydraulic nuclear power company is planning to construct dry storage facility. Spent nuclear fuel from CANDU type nuclear power plant will be stored in MACSTOR-400 composed by reinforced concrete. Because it is new model, it has to be licensed. Life time estimation is needed for licensing. Deterioration of reinforced concrete structure is currently of great concern for life time estimation. The most significant form of deterioration is reinforcement corrosion that gives rise to crack the concrete structure. In this study, in order to estimate the life time of MACSTOR, the tendency of crack creation, propagation and the effect of crack in concrete structure against radiation shielding are investigated. Crack creation and propagation depends on concrete cover thickness and c/d ratio. The surface dose rate at the concrete shield in MACSTOR is simulated by MCNP code about several cases. Generally in the case of point source, surface dose rate depends on shape, width and length of crack. In the case of MACSTOR-400, It is estimated that crack is not dominant factor in the point of radiation shielding in less than 0.4mm of crack width. Above results will be helpful to estimate the life time of concrete structure as radiation shield

  13. Neutron radiography, a powerful method to determine time-dependent moisture distributions in concrete

    International Nuclear Information System (INIS)

    Zhang Peng; Wittmann, Folker H.; Zhao Tiejun; Lehmann, Eberhard H.; Vontobel, Peter

    2011-01-01

    Highlights: ► For the first time water movement in cement-based materials could be quantified in a non-destructive way. ► neutron radiography has a sensitivity and a spatial resolution unknown so far. ► Results are essential for prediction of service life. ► Results will contribute to more durable and more ecological construction. - Abstract: Service life of reinforced concrete structures is often limited by penetration of water and compounds dissolved in water into concrete. Concrete can be damaged in this way and corrosion of steel reinforcement can be initiated. There is an urgent need to study water penetration into concrete in order to better understand deterioration mechanisms and to find appropriate ways to improve durability. Neutron radiography provides us with an advanced non-destructive technique with high spatial resolution and extraordinary sensitivity. In this contribution, neutron radiography was successfully applied to study the process of water absorption of two types of concrete with different water–cement ratios, namely 0.4 and 0.6. The influence cracks and of water repellent treatment on water absorption has been studied on mortar specimens. It is possible to visualize migration of water into concrete and other cement-based composites and to quantify the time-dependent moisture distributions as function of time with high spatial resolution by means of neutron radiography. Water penetration depth obtained from neutron radiography is in good agreement with corresponding values obtained from capillary suction tests. Surface impregnation of concrete with silane prevents capillary uptake of water. Even fine cracks are immediately filled with water as soon as the surface gets in contact. Results provide us with a solid basis for a better understanding of deteriorating processes in concrete and other cement-based materials.

  14. Comparative environmental assessment of natural and recycled aggregate concrete.

    Science.gov (United States)

    Marinković, S; Radonjanin, V; Malešev, M; Ignjatović, I

    2010-11-01

    Constant and rapid increase in construction and demolition (C&D) waste generation and consumption of natural aggregate for concrete production became one of the biggest environmental problems in the construction industry. Recycling of C&D waste represents one way to convert a waste product into a resource but the environment benefits through energy consumption, emissions and fallouts reductions are not certain. The main purpose of this study is to determine the potentials of recycled aggregate concrete (concrete made with recycled concrete aggregate) for structural applications and to compare the environmental impact of the production of two types of ready-mixed concrete: natural aggregate concrete (NAC) made entirely with river aggregate and recycled aggregate concrete (RAC) made with natural fine and recycled coarse aggregate. Based on the analysis of up-to-date experimental evidence, including own tests results, it is concluded that utilization of RAC for low-to-middle strength structural concrete and non-aggressive exposure conditions is technically feasible. The Life Cycle Assessment (LCA) is performed for raw material extraction and material production part of the concrete life cycle including transport. Assessment is based on local LCI data and on typical conditions in Serbia. Results of this specific case study show that impacts of aggregate and cement production phases are slightly larger for RAC than for NAC but the total environmental impacts depend on the natural and recycled aggregates transport distances and on transport types. Limit natural aggregate transport distances above which the environmental impacts of RAC can be equal or even lower than the impacts of NAC are calculated for the specific case study. Copyright © 2010 Elsevier Ltd. All rights reserved.

  15. Experimental and Numerical Study of FRP Encased Composite Concrete Columns

    Directory of Open Access Journals (Sweden)

    Mohsen Ishaghian

    2017-02-01

    Full Text Available A new type of composite column is presented and assessed through experimental testing and numerical modeling. The objective of this research is to investigate design options for a composite column without the use of ferrous materials. This is to avoid the current problem of deterioration of concrete due to expansion of rusting reinforcement members. Such a target can be achieved by replacing the steel reinforcement of concrete columns with pultruded I-shape glass FRP structural sections. The composite column utilizes a glass FRP tube that surrounds a pultruded I-section glass FRP, which is subsequently filled with concrete. The GFRP tube acts as a stay-in-place form in addition to providing confinement to the concrete. A total of four composite columns were tested under monotonic axial loading. The experimental ultimate capacity of each of the tested composite column was compared to the predicted numerical capacity using ANSYS program. The comparison showed that the predicted numerical values were in good agreement with the experimental ones.

  16. Interim Report on Concrete Degradation Mechanisms and Online Monitoring Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Mahadevan, Sankaran [Idaho National Lab. (INL), Idaho Falls, ID (United States); Agarwal, Vivek [Idaho National Lab. (INL), Idaho Falls, ID (United States); Neal, Kyle [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kosson, David [Idaho National Lab. (INL), Idaho Falls, ID (United States); Adams, Douglas [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-09-01

    The existing nuclear power plants in the United States have initial operating licenses of 40 years, though most of these plants have applied for and received license extensions. As plant structures, systems, and components age, their useful life—considering both structural integrity and performance—is reduced as a result of deterioration of the materials. The research on online monitoring of concrete structures conducted under the Advanced Instrumentation, Information, and Control Systems Technologies Pathway of the Light Water Reactor Sustainability Program at Idaho National Laboratory will develop and demonstrate concrete structures health monitoring capabilities. Assessment and management of aging concrete structures in nuclear plants require a more systematic approach than simple reliance on existing code margins of safety. Therefore, structural health monitoring is required to produce actionable information regarding structural integrity that supports operational and maintenance decisions. Through this research project, several national laboratories and Vanderbilt University propose to develop a framework of research activities for the health monitoring of nuclear power plant concrete structures that includes the integration of four elements—damage modeling, monitoring, data analytics, and uncertainty quantification. This report briefly discusses available techniques and ongoing challenges in each of the four elements of the proposed framework with emphasis on degradation mechanisms and online monitoring techniques.

  17. Concrete alkali-silica reaction and nuclear radiation damage

    International Nuclear Information System (INIS)

    Ichikawa, Tsuneki

    2008-01-01

    The deterioration of concrete by alkali-silica reaction of aggregates (ASR) and the effect of nuclear radiations on the ASR have been reviewed based on our studies on the mechanism of ASR and the effect of nuclear radiations on the resistivity of minerals to alkaline solution. It has been found that the ASR is initiated by the attack of alkaline solution in concrete to silicious aggregates to convert them into hydrated alkali silicate. The consumption of alkali hydroxide by the aggregates induces the dissolution of Ca 2+ ions into the solution. The alkali silicate surrounding the aggregates then reacts with Ca 2+ ions to convert to insoluble tight and rigid reaction rims. The reaction rim allows the penetration of alkaline solution but prevents the leakage of viscous alkali silicate, so that alkali silicate generated afterward is accumulated in the aggregate to give an expansive pressure enough for cracking the aggregate and the surrounding concrete. The effect of nuclear radiation on the reactivity of quartz and plagioclase, a part of major minerals composing volcanic rocks as popular aggregates, to alkaline solution has been examined for clarifying whether nuclear radiations accelerates the ASR. It has been found that the irradiation of these minerals converts them into alkali-reactive amorphous ones. The radiation dose for plagioclase is as low as 10 8 Gy, which suggests that the ASR of concrete surrounding nuclear reactors is possible to be accelerated by nuclear radiation. (author)

  18. Durapgulf, a local service life model for the durability of concrete structures in the South of Iran

    International Nuclear Information System (INIS)

    Shekarchi, M.; Ghods, P.; Alizadeh, R.; Chini, M.; Hoseini, M.

    2008-01-01

    Reinforced concrete structures were widely constructed in the south of Iran for the infrastructures of ports and oil exploration. Unfortunately, the deterioration of concrete structures in this marine area, which is mainly due to the chloride-induced corrosion of rebars in concrete, imposes hundreds of millions dollars of repair cost every year. During the last decades, extensive studies have been conducted to evaluate the effect of different parameters on chloride diffusion into concrete, corrosion initiation, and its propagation. In order to predict the time required for various steps of the corrosion phenomena, many numerical models have been developed. In this paper, development of Durapgulf (a service of life design model), which can predict the corrosion initiation of reinforced concrete (RC) structures in the south of Iran, is described and also the application of this model for service life design of RC structures is demonstrated in a hypothetical example and verified with other experimental results in this region. (author)

  19. Permeability, porosity and compressive strength of self-compacting concrete

    Directory of Open Access Journals (Sweden)

    Valcuende, M.O.

    2005-12-01

    Full Text Available Most deterioration affecting the durability of self-compacting concrete structures is mediated by water penetration in the concrete, a condition related to its porous structure. The present study analyzes these two factors. To this end, two types of concrete were prepared, a self-compacting and a traditional vibrated concrete, with different W/C ratios and different types of cement. The results of low-pressure water testing to evaluate permeability and analyses to determine compressive strength and pore size distribution showed that self-compacting concrete has lower capillary porosity than traditional concrete, which would explain its greater resistance to water penetration. Such concrete likewise reached higher strength values, except where large proportions of lime powder with low sand equivalents were used in its manufacture, when lower strength was recorded. Lastly, the depth of water penetration and compressive strength were found to be linearly correlated. That correlation was seen to depend, in turn, on the type of concrete, since for any given strength level, self-compacting concrete was less permeable than the traditional material.

    En este trabajo experimental se estudia la penetración de agua en hormigones autocompactables, analizando al mismo tiempo su estructura porosa, pues gran parte de los procesos de deterioro que afectan a la durabilidad de las estructuras están condicionados por estos dos aspectos. Para ello se han fabricado dos tipos de hormigones, uno autocompactable y otro tradicional vibrado, con diferentes relaciones A/C y distintos tipos de cemento. Tras determinar la permeabilidad al agua bajo presión, la resistencia a compresión y las distribuciones de tamaño de poro, los resultados obtenidos ponen de manifiesto que los hormigones autocompactables presentan menor porosidad capilar que los tradicionales, lo que les confiere mejores prestaciones frente a la penetración de agua. Asimismo, dichos hormigones

  20. Clinical deterioration after sildenafil cessation in patients with pulmonary hypertension

    Directory of Open Access Journals (Sweden)

    Anne M Keogh

    2008-10-01

    Full Text Available Anne M Keogh, Andrew Jabbour, Christopher S Hayward, Peter S MacdonaldHeart Lung Transplant Unit, St Vincent’s Hospital, Sydney, New South Wales, AustraliaAbstract: Sildenafil is a selective inhibitor of phosphodiesterase type 5 (PDE-5. Its chronic administration has been shown to improve exercise capacity, World Health Organization functional class, and haemodynamics in patients with symptomatic pulmonary arterial hypertension (PAH. There is however, no data describing the clinical consequences of sudden cessation of sildenafil treatment. In this series, 9 patients with NYHA Class II–IV PAH who were stable on 2 months of sildenafil monotherapy, had their sildenafil ceased to accommodate a 2-week washout period, required for enrollment in research involving an endothelin receptor antagonist. Six minute walk distance (SMWD and clinical assessments were performed before cessation of sildenafil, and again 2 weeks later. Over the course of this 2-week washout period, 6 of the 9 patients reported increased breathlessness and fatigue, 1 of these was hospitalized with worsening right heart failure. The SMWD fell in 6 patients, with falls of greater than 100 m recorded in 4 patients. This was accompanied by a worsening of NYHA Class from 2.5 ± 0.2 to 3.1 ± 0.1 (mean ± SEM, p = 0.01. These data indicate that sudden cessation of sildenafil monotherapy, in patients with PAH, carries with it a significant and unpredictable risk of rapid clinical deterioration. We recommend that if sildenafil needs to be ceased, it would be more prudent to consider concurrent vasodilator therapy before the gradual cessation of sildenafil.Keywords: sildenafil, pulmonary hypertension, phosphodiesterase inhibitor

  1. Quality inspection of concrete

    International Nuclear Information System (INIS)

    Mellmann, G.

    1983-01-01

    The testing instruction named in the pertinent standards for concrete vary considerably. They can best be judged through comparing their operating characteristic curves. Here it is noticed for the proof of the solidity of the building, that with the compressive resistances derived from the impact test, method-related severe variations influence the evaluation of the results. In the scope of tests carried out by the Federal Institute for Material Testing, through non destructive, ultrasonic echo return measurements and impact tests as well as through combined evaluation with the aid of a multiple linear regression analysis, it could be proven that a greater confidence level can be achieved and thus a more appropriate judgement of the quality of the concrete of a building is possible. (orig.) [de

  2. Drilling waste makes concrete

    International Nuclear Information System (INIS)

    Rosfjord, A.

    1993-01-01

    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 800 o C. 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 SO 2 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

  3. Reinforced concrete tomography

    International Nuclear Information System (INIS)

    Mariscotti, M.A.J.; Morixe, M.; Tarela, P.A.; Thieberger, P.

    1997-01-01

    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) [es

  4. Surface resistivity test evaluation as an indicator of the chloride permeability of concrete.

    Science.gov (United States)

    2012-12-01

    Many agencies have adopted the standard tests for electrical : indication of concretes ability to resist chloride ion penetration : (AASHTO T 277 and ASTM C1202), commonly known as the rapid : chloride permeability test (RCPT), in their specificat...

  5. Hypervelocity impact of concrete

    International Nuclear Information System (INIS)

    Watson, A.J.; Anderson, W.F.; Archer, B.

    1982-01-01

    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.) [de

  6. 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.

  7. Repair systems for deteriorated bridge piles : final report.

    Science.gov (United States)

    2017-04-01

    The objective of this research project is to develop a durable repair system for deteriorated steel bridge piles that : can be implemented without the need for dewatering. A rigorous survey of the relevant practice nationwide was : conducted to infor...

  8. Functioning of Philippine seagrass species under deteriorating light conditions

    NARCIS (Netherlands)

    Uy, W.H.

    2001-01-01

    Industrialization, urbanization and agricultural intensification result in increased sediment loading and eutrophication of S.E.Asian coastal waters and associated deterioration of light availability to seagrasses inhabiting coastal waters. In the present study, different (internal and external)

  9. Numerical simulation of CFRP-repaired reinforced concrete columns.

    Science.gov (United States)

    2014-07-01

    The overarching goal of this study was to investigate the influence of repair to individual reinforced concrete bridge columns on the : post-repair seismic performance of the bridge system. A method was developed to rapidly repair an earthquake-damag...

  10. Chapter K: Progress in the Evaluation of Alkali-Aggregate Reaction in Concrete Construction in the Pacific Northwest, United States and Canada

    Science.gov (United States)

    Shrimer, Fred H.

    2005-01-01

    The supply of aggregates suitable for use in construction and maintenance of infrastructure in western North America is a continuing concern to the engineering and resources-management community. Steady population growth throughout the region has fueled demand for high-quality aggregates, in the face of rapid depletion of existing aggregate resources and slow and difficult permitting of new sources of traditional aggregate types. In addition to these challenges, the requirement for aggregates to meet various engineering standards continues to increase. In addition to their physical-mechanical properties, other performance characteristics of construction aggregates specifically depend on their mineralogy and texture. These properties can result in deleterious chemical reactions when aggregate is used in concrete mixes. When this chemical reaction-termed 'alkali-aggregate reaction' (AAR)-occurs, it can pose a major problem for concrete structures, reducing their service life and requiring expensive repair or even replacement of the concrete. AAR is thus to be avoided in order to promote the longevity of concrete structures and to ensure that public moneys invested in infrastructure are well spent. Because the AAR phenomenon is directly related to the mineral composition, texture, and petrogenesis of the rock particles that make up aggregates, an understanding of the relation between the geology and the performance of aggregates in concrete is important. In the Pacific Northwest, some aggregates have a moderate to high AAR potential, but many others have no or only a low AAR potential. Overall, AAR is not as widespread or serious a problem in the Pacific Northwest as in other regions of North America. The identification of reactive aggregates in the Pacific Northwest and the accurate prediction of their behavior in concrete continue to present challenges for the assessment and management of geologic resources to the owners and operators of pits and quarries and to the

  11. Assessment of Concrete Repair Techniques for Radiologically-Contaminated Tank Farm Pump and Valve Pits

    International Nuclear Information System (INIS)

    MINTEER, D.J.

    2000-01-01

    As part of the scope of Project W-314, ''Tank Farm Restoration and Safe Operations,'' the condition of pump and valve pit walls and floors is being assessed, and repairs made as needed, to support upgrading the infrastructure necessary to safely transfer tank waste for treatment. Flaws in the surfaces of the pits (e.g., concrete crack/faults, protective coating deterioration) must be repaired to ensure containment integrity and to facilitate future decontamination of the pits. This engineering study presents a cost/risk/benefit evaluation of concrete and protective coating repair methods in pump and valve pits using various manual and remote tool systems

  12. A study on shear behavior of reinforced concrete beams subjected to long-term heating

    International Nuclear Information System (INIS)

    Maruta, M.; Yamazaki, M.; Miyashita, T.

    1995-01-01

    A study has been undertaken to determine the shear behavior of reinforced concrete members in nuclear power plant facilities following sustained heating to high temperatures. A total of nine specimens was tested. The parameters of the tests were (1) heating temperature (65, 90 and 175 C) and (2) heating period (1, 3, 6 or 12 months). Different combinations of these parameters were employed, and the shear strength deterioration rate was evaluated. The test results were confirmed by a non-linear finite element analysis. The relationship between the concrete compressive strengths, which varied from heating face to upper portion, and the shear strength in specimens was evaluated. (orig.)

  13. Experimental Study on Temperature Behavior of SSC (Stiffened Steel Plate Concrete) Structures

    International Nuclear Information System (INIS)

    Lee, K. J.; Ham, K. W.; Park, D. S.; Kwon, K. J.

    2008-01-01

    SSC(Stiffened Steel plate Concrete) module method uses steel plate instead of reinforcing bar and mold in existing RC structure. Steel plate modules are fabricated in advance, installed and poured with concrete in construction field, so construction period is remarkably shortened by SC module technique. In case of existence of temperature gap between internal and external structure surface such as containment building, thermal stress is taken place and as a result of it, structural strength is deteriorated. In this study, we designed two test specimens and several tests with temperature heating were conducted to evaluate temperature behavior of SSC structures and RC structure

  14. Durability predictions from rate of diffusion testing of normal portland cement, fly ash, and slag concrete

    International Nuclear Information System (INIS)

    Philipose, K.E.

    1991-09-01

    A waste repository for the belowground disposal of low-level radioactive waste, labelled IRUS (Intrusion Resistant Underground Structure), is planned at the Chalk River Laboratories. It relies greatly on the durability of concrete for a minimum of 500 years of service life. A research program based on laboratory testing to design a durable concrete and predict its useful engineered service life is in progress. The durability of concrete depends on its resistance to deterioration from both internal and external causes. Since the rate of degradation depends to a major extent on the rate of ingress of aggressive ions into concrete, laboratory testing is in progress to establish the diffusion rates of chlorides and sulphate ions. A total of 1000 concrete specimens and 500 paste specimens are being exposed at 22 degrees and 45 degrees C to twenty-five different combinations of corrosive agents, including CO 2 . Procedures to measure the ionic penetration profile and to determine the factors controlling diffusion of ions in the various concretes have been developed. The paper presents the initial results from the research program and the longevity predictions to qualify concretes for the IRUS waste repository, based on 16 months of diffusion testing on laboratory specimens

  15. Permeability and long-term durability of concrete in final repository conditions

    International Nuclear Information System (INIS)

    Pihlajavaara, S.

    1990-02-01

    The interrelation of the permeability properties and longterm durability especially in wet repository conditions has been studied. The study is based on the author's long-term experience, literary survey and experiments on the durability, service life prediction, and on water and gas permeability. Degradation models and experimental results on water and gas permeability are presented. The experiments made indicated that high class concrete is practically water and gas tight, especially in the long run when stored under water. This meant that there will hardly be any mass transfer into concrete or out of it, if concrete is of good quality. Concrete structures can be designed to meet the required service life. It can be said that practically the precision increases and the scatter decreases in the service life estimation significantly when the thickness of the anticipated deteriorated surface layer is smaller due to the higher concrete quality. The service life of well-designed concrete silo walls made of high class concrete can be predicted to be at least 1000 years in the repository conditions. (orig.)

  16. An Experimental Study on Strength and Durability for Utilization of Fly Ash in Concrete Mix

    Directory of Open Access Journals (Sweden)

    Abdulhalim Karaşin

    2014-01-01

    Full Text Available The intention of this study is to discuss the variation of concrete exposed to high sulfate environment of a specific region with respect to strength and durability. Secondly, it is aimed to discuss the possibility of reducing the cement amount in construction of concrete structures. For this purpose, laboratory tests were conducted to investigate compressive strength and sulfate resisting capacity of concrete by using 20% fly ash as mineral additives, waste materials, instead of cement. As a case study the soil samples, received from Siirt Province areas which contain high sulfate rate, have been compared with respect to sulfate standard parameters of TS 12457-4. In such regions contact of underground water seep into hardened concrete substructures poses a risk of concrete deterioration. In order to determine the variation of strength and durability for concrete exposed to such aggressive environment, the samples were rested in a solution of Na2SO4 (150 g/lt in accordance with ASTM C 1012 for the tests. As a result of this experimental study, it is noted that the use of 20% fly ash, replacement material instead of cement, has no significant effect on compressive strength of concrete over time.

  17. The effect of crack width on the service life of reinforced concrete structures

    Science.gov (United States)

    Van Hung, Nguyen; Viet Hung, Vu; Viet, Tran Bao

    2018-04-01

    Reinforced concrete has become a widely used construction material around the world. Nowadays, the assessment of deterioration and life expectancy of reinforced concrete structure is very important and necessary as concrete is a complex material with brittle failure. Under the effect of load and over time, cracks occur in the structure, significantly reducing its performance and durability. Therefore, a number of models for predicting the penetration of chloride ions into the concrete were proposed to assess the durability of the structure. In the study performed by T B Viet (2016) [1], the author proposed a new theoretical model, especially considering the effects of macro and micro cracking on the diffusion coefficient of chloride ion in the cracked concrete. The following experimental results, in term of electrical indication of concrete’s ability to resist chloride ion penetration, are used to calculate the lifespan of a reinforced concrete structure according to Dura Crete approach [8] with different crack widths to evaluate the accuracy and reliability of the above model in the range of concrete compressive strength of 30-70MPa.

  18. Evaluation of the suitability for concrete using fly ash in N.P.P. structures

    International Nuclear Information System (INIS)

    Cho, M. S.; Song, Y. C.; Kim, S. W.; Ko, K. T.

    2002-01-01

    The nuclear power plant structures constructed in Korea has been generally used type V cement(sulfate-resisting Portland cement), but according to the study results reported recently, it shows that type V cement is superior the resistance of sulfate attack, but the resistance of salt damage is weaker than type I cement. It is increased the demands on the use of mineral admixtures such as fly ash, ground granulated blast-furnace slag instead of type V cement in order to improve the durability of concrete structures. But the study on concrete mixed with fly ash in Korea has been mainly performed on rheology and strength properties of the concrete. Therefore, this study is to improve the durability of concrete structures of N.P.P. as using fly ash cement instead of type V cement. As a results, the concrete containing fly ash is improved the resistance to salt attack, sulfate attack and freezing-thawing and is deteriorated the carbonation. But if it is used the concrete with high strength or low water-powder ratio, the concrete have not problem on the durability

  19. A Production Model for Deteriorating Inventory Items with Production Disruptions

    OpenAIRE

    Yong He; Ju He

    2010-01-01

    Disruption management has recently become an active area of research. In this study, an extension is made to consider the fact that some products may deteriorate during storage. A production-inventory model for deteriorating items with production disruptions is developed. Then the optimal production and inventory plans are provided, so that the manufacturer can reduce the loss caused by disruptions. Finally, a numerical example is used to illustrate the model.

  20. Measurement of Deterioration of Frying Oil Using Electrical Properties

    OpenAIRE

    羽倉, 義雄; 佐々木, 芳浩; 鈴木, 寛一

    2006-01-01

    In this study, the relationship between the electrical properties of frying oil (relative dielectric constant and conductance) and its deterioration indicators (acid value, amounts of polymerized triacylglycerols and chromaticity) were examined, focusing on the changes in electrical properties that accompany deterioration. The samples of frying oil used in this experiment were collected from fried food processing sites (school, hospital and factory feeding centers) and were collected at closi...