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  • 1.
    Ahmed, Lamis
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Dynamic Measurements for Determining Poisson’s Ratio of Young Concrete2018In: Nordic Concrete Research, ISSN 0800-6377, no 58, p. 95-105Article in journal (Refereed)
    Abstract [en]

    Knowledge of the elastic properties of concrete at early age is often a pre-requisite for numerical calculations. This paper discusses the use of a laboratory technique for determining Poisson’s ratio at early concrete age. A non-destructive test set-up using the impact resonance method has been tested and evaluated. With the method, it has been possible to obtain results already at 7 hours of concrete age. Poisson's ratio is found to decrease sharply during the first 24 hours to reach a value of 0.08 and then increase to approximately 0.15 after seven days.

  • 2.
    Albrektsson, Joakim
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Jansson, Robert
    Silfwerbrand, Johan
    CBI .
    Assessment of fire exposed concrete structures2012In: Symposium 2012, 2012, p. 619-622Conference paper (Refereed)
    Abstract [en]

    Annually, several concrete structures, such as buildings, bridges, parking garages and tunnels are exposed to fires. An assessment is then necessary to decide whether the structure can be repaired or needs to be replaced. In a recent research project, recommendations for assessments of fire exposed concrete structures have been developed. The recommendations are based on a literature survey, results from an experimental study, where ultrasonic measurements, microscopy, Digital Image Correlation (DIC) measurement on loaded core samples were used and practical experience of real post-fire structural assessments. A refined assessment of the fire damage is obtained by combining these test methods.

  • 3.
    Albrektsson, Joakim
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Jansson, Robert
    Silfwerbrand, Johan
    CBI .
    Durability of fire exposed concrete cover considering non-linear thermal gradient, boundary effecs and polypropylene fibresManuscript (preprint) (Other academic)
  • 4.
    Andersson, Louise
    et al.
    RISE.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Selander, Anders
    Cementa.
    Trägårdh, Jan
    RISE.
    Continuous Preventive Bridge Maintenance in Sweden – Field Experiment on the Effect of Washing on Concrete Bridges2019In: Proceedings of the fib Symposium 2019: Concrete - Innovations in Materials, Design and Structures, 2019Conference paper (Refereed)
    Abstract [en]

    Bridges are an important part of the infrastructure. For the bridges to have the longest possible service life with minimum repairs, the maintenance is of great importance. One type of bridge maintenance that is rarely researched is the continuous preventive maintenance. The continuous preventive maintenance consists of removal of vegetation, cleaning of bridge joints and drainage systems as well as high-pressure washing of the structure. The effects of washing is heavily discussed but not properly researched. A study on the effectiveness of washing concrete is therefore being conducted. A field experiment has been initiated where concrete specimens are installed on an edge beam of a road bridge. The specimens are of two recipes where one represents an old bridge with rather high water-cement ratio and the other one represents a new bridge with a low water-cement ratio. 50% of the specimens are washed annually, while the others are not. Each year samples are collected and tested for a chloride profile. The results for the first year of exposure have been determined. They are promising but are still only very preliminary. The effect of washing, if any, will be visible after a longer exposure.

  • 5.
    Ansell, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Holmgren, Jonas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Mundt, Elisabeth
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Services Engineering (name changed to Building Service and Energy Systems 2012-03-01).
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Stille, Håkan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Sundquist, Håkan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    State-of-the-art och förslag till forskningsprojekt: Drift, underhåll och reparation av trafiktunnlar2007Report (Other academic)
  • 6.
    Ansell, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Sprängavstånd till ung gjuten och sprutad betong2007Report (Other academic)
  • 7.
    Ansell, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges.
    The vibration resistance of young and early age concrete2003In: Structural Concrete, ISSN 1464-4177, E-ISSN 1751-7648, Vol. 4, p. 125-134Article in journal (Refereed)
    Abstract [en]

    During early age, concrete is vulnerable to disturbance from vibrations of large magnitudes. Today, conservative vibration limits are used as standards, and guidelines provide little information. The literature cited in this study contains experiences and results from the construction and civil engineering field, in-situ testing, laboratory testing and computer modelling. On the basis of the reviewed literature, recommended maximum vibration levels for young and early-age concrete are given.

  • 8.
    Ansell, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges (name changed 20110630).
    Sundquist, Håkan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges (name changed 20110630).
    Krympning, pågjutningar och samverkan hos betongkonstruktioner2006Report (Other academic)
  • 9.
    Billberg, Peter
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Holmgren, J
    SCC Structural Behaviour at Restand Its Influence on Form Pressure2006In: RILEM Materials and Structures Journal, ISSN 1359-5997Article in journal (Refereed)
  • 10.
    Billberg, Peter
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Österberg, Thomas
    Form Pressures Generated by Self-Consolidating Concrete2005In: Concrete International, ISSN 0162-4075, E-ISSN 1944-7388, Vol. 27, no 10, p. 35-42Article in journal (Refereed)
    Abstract [en]

    Since its development, it has been generally assumed that self-consolidating concrete (SCC) would generate hydrostatic formwork pressure due to the rate at which it can be cast and the long time before it starts to set. However, in 1998 when the first bridges were cast using SCC in Sweden, measured form pressures were even lower than the design values for conventional concrete. To investigate the need for special formwork design considerations when using SCC, a series of eight wall specimens were cast, and the resulting form pressures were monitored.

  • 11.
    de Frias Lopez, Ricardo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Ekblad, Jonas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway Engineering Laboratory.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    A Numerical Study on the Permanent Deformation of Gap-Graded Granular Mixtures2016In: Proceedings of the Third International Conference on Railway Technology: Research, Development and Maintenance / [ed] J. Pombo, Stirlingshire, UK: Civil-Comp Press , 2016Conference paper (Refereed)
    Abstract [en]

    Permanent deformation accumulation of unbound granular layers under traffic plays a critical role in the performance and need for maintenance of pavements and railway structures. In this paper, the discrete element method is used to study the permanent strain behaviour of binary mixtures of elastic spheres, as an idealization of gap-graded mixtures, under triaxial monotonic loading. The effects of stress level and soil fabric structure, based on a recently proposed classification system founded on micromechanical considerations, are assessed by subjecting mixtures with varying fines contents to different stress levels. Additionally, mixtures are loaded to static failure to study the dependency of the permanent strains on the closeness of the applied stress to failure stress, in accordance with existing empirical models. Numerical results are also compared with the experimentally determined behaviour of granular materials. The findings indicate that numerical mixtures are able to reproduce some of the most significant features observed in laboratory tests on granular materials, further encouraging the use of numerical simulations to enhance the understanding of granular media behaviour. Additionally, a good correlation between fabric structure and performance is obtained, giving additional support to the use of the studied fabric classification system for performance characterization.

  • 12.
    de Frias Lopez, Ricardo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Ekblad, Jonas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway Engineering Laboratory.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Resilient properties of binary granular mixtures: A numerical investigatio2016In: Computers and geotechnics, ISSN 0266-352X, E-ISSN 1873-7633, Vol. 76, p. 222-233Article in journal (Refereed)
    Abstract [en]

    The effect of stress level on the resilient modulus for binary mixtures of elastic spheres under triaxial loading is investigated using the discrete element method. The secant modulus during the first cycle of unloading is used as an estimate of the modulus after several load cycles due to computational time restrains. Later in the paper, its adequacy as an accurate and efficient estimator is shown. Numerical results are statistically compared with existing relations characterizing the stress dependency of the resilient modulus for real granular materials. It is concluded that the modulus prediction is significantly improved considering the effect of the deviator stress in addition to the confinement stress, obtaining a good correlation between the modulus and the confinement to deviator stress ratio for the numerical mixtures. The stress dependency of a recently proposed soil fabric classification system, based on force transmission considerations at particulate level, is also studied and its correlation with performance investigated. It is found that the relative load-bearing role of coarse and fine components is governed by the deviator to confinement stress ratio. However, the implemented fabric classification is fairly insensitive to changes in this ratio. Regarding resilient performance, interactive fabrics show the stiffest response whereas underfilled fabrics should be avoided due to a potential for instability.

  • 13.
    de Frias Lopez, Ricardo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    A discrete element material model including particle degradation suitable for rockfill embankments2019In: Computers and geotechnics, ISSN 0266-352X, E-ISSN 1873-7633, Vol. 115, article id 103166Article in journal (Refereed)
    Abstract [en]

    A material model for future implementation in high rockfill embankments has been developed using discrete elements. Compared to previous modelling of railway ballast representing particles as clumps of spheres with bonded asperities, much simpler breakable clumps are used. This allows considering not only corner breakage but also particle splitting without a prohibitive computational time, something unique when modelling three-dimensional assemblies of particles. Moreover, breakage is controlled by values of contact forces and particle loading configuration, resulting in significantly fewer parameters and with a much clearer physical meaning. All in all, it results in a more computationally efficient and robust model suitable for implementation in rockfill embankments. Numerical monotonic and cyclic triaxial tests are performed under a range of low deviatoric to confinement stress ratios, as anticipated for railway embankments. A comparable degree of resemblance to empirical results as the previous modelling efforts with bonded asperities is observed when including degradation. Results at particle level proved useful to partially explain the observed macroscopic responses; however, these were substantially affected by breakage and none of the studied variables could, on its own, satisfactorily fully explain the observed behaviour. As a matter of fact, a complex interdependency of different factors, both at particle and macroscopic level, was identified that ultimately explained the macroscopic response. The key contribution is thus presenting an efficient and realistic material model specifically aimed at modelling high rockfill embankments including degradation, something not attempted to date.

  • 14.
    de Frias Lopez, Ricardo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Jelagin, Denis
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway Engineering Laboratory. School of Engineering and Applied Science, Aston University, Birmingham, UK.
    Force transmission and soil fabric of binary granular mixtures2016In: Geotechnique, ISSN 0016-8505, E-ISSN 1751-7656, Vol. 66, no 7, p. 578-583Article in journal (Refereed)
    Abstract [en]

    The effect of fines content on force transmission and fabric development of gap-graded mixtures under triaxial compression has been studied using the discrete-element method. Results were used to define load-bearing soil fabrics where the relative contributions of coarse and fine components are explicitly quantified in terms of force transmission. Comparison with previous findings suggests that lower particle size ratios result in higher interaction between components. A potential for instability was detected for underfilled fabrics in agreement with recent findings. It was also found that the threshold fines content provides an accurate macroscopic estimation of the transition between underfilled and overfilled fabrics.

  • 15. Döse, M.
    et al.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Jelinek, C.
    Trägårdh, J.
    Isaksson, M.
    Naturally occurring radioactivity in some Swedish concretes and their constituents: Assessment by using I-index and dose-model2016In: Journal of Environmental Radioactivity, ISSN 0265-931X, E-ISSN 1879-1700, Vol. 155-156, p. 105-111Article in journal (Refereed)
    Abstract [en]

    The reference level for effective dose due to gamma radiation from building materials and construction products used for dwellings is set to 1 mSv per year (EC, 1996, 1999), (CE, 2014). Given the specific conditions presented by the EC in report 112 (1999) considering building and construction materials, an I-index of 1 may generate an effective dose of 1 mSv per year. This paper presents a comparison of the activity concentrations of 4 0K, 226Ra and 232Th of aggregates and when these aggregates constitute a part of concrete. The activity concentration assessment tool for building and construction materials, the I-index, introduced by the EC in 1996, is used in the comparison. A comparison of the I-indices values are also made with a recently presented dose model by Hoffman (2014), where density variations of the construction material and thickness of the construction walls within the building are considered. There was a ~16-19% lower activity index in concretes than in the corresponding aggregates. The model by Hoffman further implies that the differences between the I-indices of aggregates and the concretes' final effective doses are even larger. The difference is due, mainly to a dilution effect of the added cement with low levels of natural radioisotopes, but also to a different and slightly higher subtracted background value (terrestrial value) used in the modeled calculation of the revised I-index by Hoffman (2014). Only very minimal contributions to the annual dose could be related to the water and additives used, due to their very low content of radionuclides reported.

  • 16.
    Döse, Magnus
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Evaluation of the I-index by use of a portable hand-held spectrometer and laboratory methods: a risk assessment of Swedish concrete by use of different crushed aggregates2014In: Mineralproduksjon, ISSN 1893-1057, E-ISSN 1893-1170, no 5, p. A35-A52Article in journal (Other academic)
    Abstract [en]

    The recommended levels of ionizing radiation from construction materials in effective dose is set to a maximum of 1 mSv/year, EC (1996, 1999, 2013), ICRP (2007), IAEA (2011). By using a theoretical model proposed by the European Union (1999), this is equivalent to I-index 1. By using of concrete slabs with dimensions of 1.5 m × 1.5 m × 0.15 m, an empirical approach is suggested for the calculation of the I-index of naturally occurring ionizing radiation from construction materials. Measurements of 40K, 226Ra, 232Th and the total gamma radiation were conducted and the I-index values were calculated for each concrete mix. A good linear relationship could be established between measurements performed by the Swedish Cement and Research Institute (CBI) and the laboratory results acquired from the Radiation and Nuclear Safety Authority of Finland (STUK) and Centre de Recherches Pétrographique et Géochimiques/ Le Centre National de la Recherche Scientifique (CRPG/CNRS). The results indicate that 60 % of the investigated construction materials are in agreement with the stipulated levels set out by the EC (1999, 2013). The cause for the higher levels of ionizing radiation is often elevated concentrations of all the radioactive elements measured. Regarding the concrete samples yielding values of I-index > 1, 232Th makes the largest contribution.

  • 17.
    Döse, Magnus
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures. RISE CBI Betonginstitutet.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Reduction of radon gas in concrete – effects and evaluation of effective dose2017In: Nordic Concrete Research / [ed] Marianne Tange Hasholt, Oslo, Norway, 2017, Vol. 1, p. 185-188Conference paper (Refereed)
    Abstract [en]

    The second largest cause of lung cancer is related to radon (222Rn) and its progenies in our environment. Building materials, such as concrete, contribute to the production of radon gas through the natural decay of 238U from its constituents. The Swedish Cement and Concrete Research Institute (CBI) has examined two identical concrete recipes where only an additive, X1002 Hycrete hydrophobant corrosion inhibitor was added to one of the recipes as a mean to lower the radon exhalation rate. Measurements were performed with an ATMOS 33 ionizing pulsation chamber at four different occasions for each recipe during 12 months. The results indicate a reduction of the exhalation rate by approximately 30-35 %, meaning roughly 2 mSv per year decrease in effective dose to a human.

  • 18.
    Döse, Magnus
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures. RISE CBI Betonginstitutet.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Reduction of Radon Gas in Concrete Using Admixtures and Additives2018In: Nordic Concrete Research, ISSN 0800-6377, Nordic Concrete Research, ISSN 2545-2819, Vol. 58, article id ncr-2018-0002Article in journal (Refereed)
    Abstract [en]

    The second largest cause of lung cancer is related to radon (222Rn) and its progenies in our environment. Building materials, such as concrete, contribute to the production of radon gas through the natural decay of 238U from its constituents. The Swedish Cement and Concrete Research Institute (CBI) has examined three concrete recipes where only an additive as well as fly ash were added as single constituents to a reference recipe and compared to a reference concrete. The inputs of an additive as well as a supplementary cementitious material (fly ash) were made as a mean to investigate their potential influence on the radon exhalation rates of the concrete. Measurements were performed with an ATMOS 33 ionizing pulsation chamber for at least five different occasions for each recipe during a 22 month period. The results indicate a reduction of the exhalation rate by approximately 30-35 % for each altered recipe. This means roughly 1.5-2 mSv per year decrease in effective dose to a human using an additive or a supplementary cementitious material such as fly ash in relation to the investigated standard concrete.

  • 19.
    Döse, Magnus
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures. RISE CBI BETONGINSTITUTET AB.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures. KTH.
    Supplementary Cementitious Materials and Additives – Effective Measures to Hinder Radon in Concrete2018Conference paper (Refereed)
    Abstract [en]

    The second largest cause of lung cancer is related to radon (222Rn) and its progenies in our environment. Building materials, such as concrete, contribute to the production of radon gas through the natural decay of 238U from its constituents. The Swedish Cement and Concrete Research Institute (CBI) has examined ten different concrete recipes containing an additive or Supplementary Cementious Material (SCM), such as fly ash, slag or silica and combinations thereof. The SCM´s were added in small to moderate portions and substituted the reference Portland cement (OPC). The inputs of an additive as well as a supplementary cementitious material were made as a mean to investigate their potential influence on the radon exhalation rates of the concrete as well as the radon gas diffusion length (L) that could be expected from the different recipes. Measurements were performed with an ATMOS 33 ionizing pulsation chamber. The results indicate a reduction of the exhalation rate by approximately 10-55 % depending on recipe at an RH of 75 %. The diffusion coefficients, corrected for background subtraction vary in the interval 1.1 x 10-10 – 7.6 x 10-12 m2/s. The diffusion lengths vary between 2 and 9 mm. In the case where the largest reduction of the exhalation rate is achieved, this roughly correspond to >2 mSv per year decrease in effective dose to a human. Consequently, using an additive or a SCM, as part of the mix, would be an option to effectively lower the radon gas exhalation in their initial stage of production. Secondly, the use of additives and SCM´s will contribute to a lower environmental impact (CO2).

  • 20.
    Emborg, Mats
    et al.
    LTU.
    Ohlsson, Ulf
    LTU.
    Persson, Martin
    LTU.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Slitbetong som brobeläggning2019In: Betong, no 1, p. 43-46Article in journal (Other (popular science, discussion, etc.))
  • 21.
    Enckell, Merit
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Egede Andersen, Jacob
    Glisic, Branko
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    New and Emerging Technologies in Structural Health Monitoring2013In: Handbook of Measurement in Science and Engineering: Volume 1 / [ed] Myer Kutz, Hoboken, New Jersey: Wiley , 2013, p. 3-78Chapter in book (Other academic)
  • 22.
    Enckell, Merit
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges.
    Silfwerbrand, Johan L.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges.
    Gathered Knowledge of Structural Health Monitoring of Bridges with Fibre Optic Sensors2011In: Proceedings of the ICE - Bridge Engineering: on 13 October 2011, 2011Conference paper (Other academic)
  • 23.
    Flansbjer, Mathias
    et al.
    SP Technical Research Institute of Sweden.
    Lindqvist, Jan-Erik
    CBI Swedish Cement and Concrete Research Institute.
    Silfwerbrand, Johan
    CBI Swedish Cement and Concrete Research Institute.
    Quantitative Characteristics in Shear Load2011In: fib Symposium PRAGUE 2011 - Proceedings, 2011, p. 567-570Conference paper (Other academic)
  • 24.
    Gram, Annika
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Farhang, Ali
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Computer-aided modelling and simulation of self-compacting concrete flow2007In: Proceedings pro054: Self-Compacting Concrete - SCC 2007 / [ed] G. De Schutter and V. Boel, RILEM Publications SARL , 2007, p. 455-460Conference paper (Refereed)
    Abstract [en]

     The flow behaviour of SCC is currently being investigated as an ongoing PhD project. This paper presents a development of the Distinct Element Method using the commercial software PFC3D to model the flow of SCC. A good correspondence was obtained between laboratory test and numerical result for the slump flow test.

  • 25.
    Gram, Annika
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    McCarthy, R.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Linking Numerical Simulation of Fresh Concrete Flow to On-Site Casting2009In: Cement and Concrete Research, ISSN 0008-8846, E-ISSN 1873-3948Article in journal (Refereed)
  • 26.
    Gram, Annika
    et al.
    Swedish Cement and Concrete Research Institute, CBI.
    Silfwerbrand, Johan
    Swedish Cement and Concrete Research Institute, CBI.
    Applications for Numerical Simulation of Self-Compacting Concrete2010In: Nordic Concrete Research, ISSN 0800-6377, no 2/2010, p. 143-154Article in journal (Refereed)
    Abstract [en]

    This paper, presenting practical applications for numerical simulation, is divided into two parts: 1. Verification and application of the numerical concrete model presented here and 2. Introduction of an on-site rheology assessment tool, the Rheo-Box, which is to be used for the concrete acceptance test in order to verify rheological parameters of the concrete as feedback to obtain satisfactory form filling. It is shown that simulated values correspond well to both analytical and experimental results for concrete flow. In the future, numerical simulation will be a more common tool for predictions of possibly complicated SCC castings.

  • 27.
    Gram, Annika
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Computer simulation of SCC flow2007In: Betonwerk und Fertigteil-Technik/Concrete Plant and Precast Technology, ISSN 0373-4331, Vol. 73, no 8, p. 40-48Article in journal (Refereed)
    Abstract [en]

    Starting in 1993, Sweden was, inspired by Japanese research in the concrete field, the first European country to develop the revolutionary material called Self Compacting Concrete (SCC). The Swedish Cement and Concrete Research Institute (CBI) was one of the pioneer research environments on SCC in Europe; f. i. the first European SCC bridges were cast in Sweden in 1998. Furthermore, an SCC flow a simulation project was started; in 2000 at CBI. The used particle based software is icalled Particle Flow Code (PFC) and is based on the Distinct Element Method (DEM).

  • 28.
    Gram, Annika
    et al.
    Swedish Cement and Concrete Research Institute.
    Silfwerbrand, Johan
    Swedish Cement and Concrete Research Institute.
    Numerical Simulation of Fresh SCC Flow: Applications2011In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 44, no 4, p. 805-813Article in journal (Refereed)
    Abstract [en]

    Numerical simulation of self-compacting concrete (SCC) flow shows great potential for developing into a powerful tool for prediction of SCC form filling. Numerical simulation is also of interest for modelling small scale material phenomena. This paper presents three different applications useful for modelling different phenomena on different scales: (i) particles, each representing an aggregate in the concrete, (ii) fluid, modelling concrete as a homogeneous liquid and (iii) particle in fluid, studying details of flow. The methods are compared and evaluated in order to give the reader a quick guidance into the world of possibilities that open up with numerical simulation.

  • 29.
    Gram, Annika
    et al.
    Swedish Cement and Concrete Research Institute.
    Silfwerbrand, Johan L
    Swedish Cement and Concrete Research Institute.
    Simulation of Fresh Concrete Channel Flow: Evaluation of Rheological Parameters2010In: 8th fib International PhD Symposium in Civil Engineering, 2010, p. 389-394Conference paper (Other academic)
  • 30.
    Gram, Annika
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Silfwerbrand, Johan L.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Lagerblad, Björn
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Particle motion in fluid: Analytical and Numerical Study2016In: Applied Rheology, ISSN 1430-6395, E-ISSN 1617-8106, Vol. 26, no 2Article in journal (Refereed)
    Abstract [en]

    Particle motion in fluid is discussed for one-particle systems as well as for dense suspensions, such as cementitious materials. The difference in large particle motion between larger particles and behaviour of fines (<125 μm) is explained, motion of one particle is shown by numerical simulation. It is concluded and highlighted that it is the particular motion of the fines that to a large extent contribute to the rheological properties of a suspension. It is also shown why larger ellipsoidal particles do not necessarily contribute to the increase of viscosity.

  • 31.
    Gram, Annika
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures. Swedish Cement and Concrete Research Institute (CBI), Sweden.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures. Swedish Cement and Concrete Research Institute (CBI), Sweden.
    Lagerblad, Björn
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures. Swedish Cement and Concrete Research Institute (CBI), Sweden.
    Obtaining rheological parameters from flow test - Analytical, computational and lab test approach2014In: Cement and Concrete Research, ISSN 0008-8846, E-ISSN 1873-3948, Vol. 63, p. 29-34Article in journal (Refereed)
    Abstract [en]

    In the mix design process of cementitious suspensions, an adequate rheology of the cement paste is crucial. A novel rheological field test device for cementitious fluids is presented here and investigated theoretically, by computer simulation and by lab tests. A simple flow stoppage test with a timed spread passage point provides accurate rheological parameters according to the Bingham material model. Values for yield stress and plastic viscosity are obtained for a test specimen of no more than 19.75 . 10(-6) m(3) of fluid. This volume is equivalent to 19.75 g of water at room temperature. Such a small volume allows reliable tests even for small amounts of fillers. Promising results show that both yield stress and plastic viscosity can be determined by this simple test. This novel rheological test method also enables the correlation of different rheological equipment used by different laboratories.

  • 32.
    Gram, Annika
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures. Swedish Cement and Concrete Research Institute (CBI), Sweden.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures. Swedish Cement and Concrete Research Institute (CBI), Sweden.
    Lagerblad, Björn
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures. Swedish Cement and Concrete Research Institute (CBI), Sweden.
    Particle Motion in Fluid: Analytical and Numerical StudyManuscript (preprint) (Other academic)
  • 33.
    Hedebratt, Jerry
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges (name changed 20110630).
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges (name changed 20110630).
    Damages in Industrial Concrete Floors2008In: Industrial floors: recomendation for design, material selection, execution, operation and maintenance, Swedish Concrete Society , 2008, p. 63-85Chapter in book (Refereed)
  • 34.
    Hedebratt, Jerry
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges (name changed 20110630).
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges (name changed 20110630).
    Full-scale test on a pile supported floor slab - steel fibre concrete only or in a combination with steel2008Conference paper (Other academic)
  • 35.
    Hedebratt, Jerry
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Full-scale tests on pile supported floor slabs-steel fibre concrete only or in a combination with steel2005In: ISISS 2005: Innovation & Sustainability of Structures, Vol 1-3 / [ed] Lu, Z; Li, A; Wu, Z; Meng, S, Nanjing, China: Southeast University Press , 2005, p. 437-448Conference paper (Refereed)
    Abstract [en]

    The Ph. D project "Integrated Design and Construction of Industrial Floors" proceeds after the presentation of a Licentiate thesis covering methods to Increase the quality of concrete floors/5/. The aim for further studies is to develop directions for purchasing, design and construction of pile supported steel fibre concrete, SFC floors. SFC is common in industrial floor slabs. In pile supported floor slabs also a combination of non-tensioned reinforcing bars and steel fibres have been used. Furthermore, neither Swedish nor European or any other known design guidelines cover steel fibres as only the reinforcement in pile supported floors. A common engineering advice is to disregarding the ground support. The scope is to investigate the possibility to consider steel fibre only design solutions in a safe way and to compare it with a Combined solution and as a reference performing full-scale tests and to develop design guideline's also considering the actual ground support. The Falling Weight Deflectiometer is a promising method testing the ground support.

  • 36.
    Hedebratt, Jerry
    et al.
    KTH, Superseded Departments, Civil and Architectural Engineering.
    Silfwerbrand, Johan L.
    KTH, Superseded Departments, Civil and Architectural Engineering.
    An Innovative Approach to the Design of Pile Supported SFRC Slabs2004Conference paper (Other academic)
  • 37.
    Hedebratt, Jerry
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges.
    Silfwerbrand, Johan L.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges.
    Design Models for Pile-Supported Slabs2007Conference paper (Other academic)
  • 38.
    Hedebratt, Jerry
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Silfwerbrand, Johan L.
    Swedish Cement & Concrete Res Inst, Stockholm, Sweden.
    Full-scale test of a pile supported steel fibre concrete slab2014In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 47, no 4, p. 647-666Article in journal (Refereed)
    Abstract [en]

    The aim of the short-term studies is to investigate the structural behaviour of pile supported slabs made of steel fibre concrete (SFC) only and combined reinforced steel fibre concrete. The studies include tests on an elevated slab where a combination of reinforcement bars and steel fibres have been used in one half of the slab and SFC only in the other half. The tests were performed on a column-supported elevated slab that simulates a half scale model of an industrial pile-supported floor slab. The short-term tests showed considerable structural and crack arresting performance that also increased with a higher dosage of fibres. A small addition of conventional reinforcement bars further increased the ultimate load capacity P (Max). P (Max) was in the range of 125-298 kN for the two types of slab. The results indicate that SFC can be used with verifiable results in structural applications for elevated slabs and pile-supported floor slabs despite that the material testing from the ordered SFC showed a larger scatter in properties and that the calculated load capacities were only 40-220 kN. Main causes of deviance are arch and membrane effects.

  • 39.
    Hedebratt, Jerry
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges (name changed 20110630).
    Silfwerbrand, Johan L
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges (name changed 20110630).
    Full-Scale Test on a Pile Supported Floor Slab – Steel Fibre Concrete Only or in a Combination with Steel2008Conference paper (Other academic)
    Abstract [en]

    The Ph. D project “Integrated Design and Construction of Industrial Floors” proceeds after the presentation of a Licentiate thesis covering methods to increase the quality of concrete floors, Hedebratt (2004). The aim for further studies is to develop directions for design and construction of pile supported steel fibre concrete, SFC floors. SFC is common in industrial floor slabs. In pile supported floor slabs also a combination of non-tensioned reinforcing bars and steel fibres have been used. Furthermore, neither Swedish nor European or any other known design guidelines cover steel fibres as the only reinforcement in pile supported floors or structural members.A common engineering advice is to disregard the ground support. The scope is to investigate the possibility to consider steel fibre only design solutions in a safe way and to compare it with a combined solution and as a reference performing full-scale tests and to develop design guidelines. The now ongoing test on a column supported deck emulates a half scale of an industrial supported floor slab but may also be considered to be full scale of a structural mushroom floor for small housing.

  • 40.
    Hedebratt, Jerry
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges.
    Silfwerbrand, Johan L.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges.
    Lessons Learned: Swedish Design and Construction of Industrial Concrete Floors2007Conference paper (Other academic)
  • 41.
    Hedebratt, Jerry
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Silfwerbrand, Johan L.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Lessons Learned: Swedish Design and Construction of Industrial Concrete Floors2012In: Nordic Concrete Research, ISSN 0800-6377, Vol. 45, p. 75-91Article in journal (Other academic)
  • 42.
    Hedebratt, Jerry
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Silfwerbrand, Johan L.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Long Term Full Scale Test of a Pile Supported Steel Fibre Concrete SlabArticle in journal (Other academic)
  • 43. Hellström, Arne
    et al.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Beräkna stommars livslängd till 400 år2019In: Betong, ISSN 1101-9190, no 1, p. 57-58Article in journal (Other (popular science, discussion, etc.))
  • 44.
    Jansson, Robert
    et al.
    Swedish Technical Research Institute.
    Boström, Lars
    Swedish Technical Research Institute.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Fire spalling of concreteManuscript (preprint) (Other academic)
    Abstract [en]

    When occurring fire spalling of concrete is a phenomenon that reduces the fire resistance of fire exposed members by loss of cross section. The reduction of strength by the presence of moisture is a main component in the fire spalling phenomena during fire exposure from one side. Without including this effect the function of an addition of polypropylene fibres could not be fully explained. In many experiments the crack leading to the formation of a flaking off occurs at a temperature substantially lower than the temperatures where the pressure from saturated steam is high enough to be the main driving force for the phenomenon. Also no simple correlation between measured pore pressures and the fire spalling phenomenon has been found. The present study made by testing the compressive strength of small mortar specimens shows that a specimen boiled for 10 minutes has only 64% of the strength of a dry specimen. This result highlights the substantial strength reducing effect of the presence of moisture at elevated temperatures independent of the pore pressure. The presence of polypropylene fibres reduces the moisture content around the critical zone.

  • 45.
    Jansson, Robert
    et al.
    Swedish Technical Research Institute.
    Sjöström, Johan
    Swedish Technical Research Institute.
    Boström, Lars
    Swedish Technical Research Institute.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Reduction of fire spalling of concrete with small doses of polypropylene fibersManuscript (preprint) (Other academic)
    Abstract [en]

    The addition of polypropylene fibers has been shown to reduce the fire spalling propensity of concrete. This has been proven in many fire tests; but, very few large scale tests exist showing the function of polypropylene fibers at low dosages. In this study results on polypropylene fibers included in w/c 0.40 mixes typical used in tunnel construction that is spalling sensitive without fibers shows that an amount of only 0.6 kg/m3 (1.01 lb/yd3) has a significant effect on the spalling propensity and that even lower amounts reduce the spalling although they do not eliminate it entirely. During one of the fire tests on large slabs loaded in compression, unloaded cubes of the same mixes were also included in the furnace. None of the small specimens spalled whereas some of the corresponding large slabs spalled beyond the layer of reinforcement. This showed that the cube test method is not conservative.

  • 46.
    Johansson, A.
    et al.
    Swedish Cement and Concrete Research Institute, Stockholm, Sweden.
    Janz, M, M
    Swedish Cement and Concrete Research Institute, Stockholm, Sweden.
    Trägårdh, J.
    Swedish Cement and Concrete Research Institute, Stockholm, Sweden.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Protection of concrete with water repellent agents: What is required to achieve a sufficient penetration depth2009In: Concrete Repair, Rehabilitation and Retrofitting II: Proceedings of the 2nd International Conference on Concrete Repair, Rehabilitation and Retrofitting, ICCRRR, 2009, p. 287-288Conference paper (Refereed)
    Abstract [en]

    Water repellent agents such as silanes have been shown to give a good protection against moisture and chlorides and thereby prolonging the service life for the construction. However, a requirement for a successful impregnation is a sufficient penetration depth. The effective penetration depth of different silanes was measured by cracking water repellent treated concrete plates, spraying water on the cracked surface and measuring the distance from surface to the sharp line between dry and wet concrete. The results are presented as a function of three parameters: time, degree of saturation and porosity. They show how these factors affect the effective penetration depth of the silane. It can be seen that by prolonging the treatment from one to five hours results in doubling the penetration depth something which easily can be achieved for example by using a paste instead of a liquid.

  • 47.
    Johansson, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Janz, Mårten
    Silfwerbrand, Johan
    Trägårdh, J.
    Moisture fixation in concrete treated with a water repellent agentIn: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873Article in journal (Other academic)
  • 48.
    Johansson, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Janz, Mårten
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Trägårdh, Jan
    Impregnation of concrete structures - introduction to a PhD-project2005In:  Proceedings Hydrophobe IV: water repellent treatment of building materials, Freiburg, Switzerland: Aedification Publishers , 2005, p. 59-68Conference paper (Refereed)
    Abstract [en]

    Moisture is the source of most damage in concrete bridges, such as frost damage and reinforcement corrosion. Experiments and field investigations show that impregnation with silanes and siloxanes provide good protection against moisture for at least eight to ten years. But most of the research only verifies this without providing a reason for the positive results. This project analyses how common impregnation substances work in concrete. Additionally, the authors develop models in order to explain these effects. As a first step, it is important to obtain reliable data on how the moisture diffusion coefficient is affected by hydrophobic treatments. Some of the factors investigated are how the water-cement ratio and the impregnation depth will influence moisture transport. One of the goals is to create a computer model to predict the moisture and chloride content over time when the geometry, the material properties of the concrete structure and the environmental conditions are known.

  • 49. Johansson, Anders
    et al.
    Janz, Mårten
    Silfwerbrand, Johan
    Trägårdh, Jan
    Long Term Performance of Water Repellent Treatment: Water Absorption Tests of Field Objects in Stockholm2008In: International Journal on Restoration of Buildings and Monuments, ISSN 0947-4498, Vol. 14, no 1, p. 39-47Article in journal (Refereed)
  • 50.
    Johansson, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges (name changed 20110630).
    Janz, Mårten
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges (name changed 20110630).
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges (name changed 20110630).
    Trägårdh, Jan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges (name changed 20110630).
    Moisture Diffusion Coefficient of Impregnated Concrete2005Conference paper (Other academic)
1234 1 - 50 of 161
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