Change search
Refine search result
12 1 - 50 of 97
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Abbasiverki, Roghayeh
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Malm, Richard
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Analysis of shallowly buried reinforced concrete pipelines subjected to earthquake loads2014In: Nordic Concrete Research, ISSN 0800-6377, no 51, p. 111-130Article in journal (Refereed)
    Abstract [en]

    Buried reinforced concrete pipelines are widelyused in e.g. water and wastewater systems. Failure of these infrastructures mayresult in drastic effects and recently they have been brought into focus asvital components in safety systems for nuclear power installations. The highlevel of safety has here lead to a demand for reliable earthquake risk analyses.In this paper, methods are compared and the use of seismic design loadsdemonstrated. FE analysis in 2D of soil-pipe interaction under seismic wavepropagation is performed. The performance of concrete pipes subjected toseismic waves with different frequency content is evaluated with respect todifferent soil condition but also water mass effect.

  • 2.
    Ahmed, Lamis
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Malm, Richard
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Finite element simulation of shotcrete exposed to underground explosions2012In: Nordic Concrete Research, ISSN 0800-6377, no 45, p. 59-74Article in journal (Refereed)
    Abstract [en]

    An elastic finite element model is used tosimulate theinducedstress waves from blasting, propagating in rock towards shotcrete on a tunnel wall. Due to the inhomogeneous nature of the rock, the stress wavesattenuate onitsway from the point of explosiontowardsthe shotcrete on the rock surface. Material damping for the rock-mass is estimated from in-situ measurements. The vibration resistance of the shotcrete-rock support system depends on the material properties of the shotcrete. Age-dependent material properties are varied to investigate the behaviour of young shotcrete subjected to blast loading. Finally, finite element analysis results are presented and verified through comparison with other numerical models, measurements and observations.

  • 3.
    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.

  • 4.
    Al-Gburi, Majid
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Effect of the boundary conditions on the crack distribution in early age concrete2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 347-351Article in journal (Refereed)
    Abstract [en]

    Restrained movement in early age concrete may cause cracking. The boundary conditions – restraint – influence the possible crack distribution. This study aims at highlighting the effect of such restraint on the crack distribution. This is done by using the “Cracking Model for Concrete” in ABAQUS/Explicit simulating the non-linear behaviour under and after cracking. In the study the typical case wall-on-slab was in focus using a structure previously been tested in laboratory with both fixed and free bottom slab. The result of the modelling shows fairly good agreement with the cracks observed in the tests.

  • 5.
    Al-Gburi, Majid
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hösthagen, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Simplified methods for crack risk analyses of early age concrete: Part 1: Development of Equivalent Restraint Method2012In: Nordic Concrete Research, ISSN 0800-6377, Vol. 46, no 2, p. 17-38Article in journal (Refereed)
    Abstract [en]

    The present study deals with both the compensation plane method, CPM, and local restraint method, LRM, as alternative methods studying crack risks for early age concrete. It is shown that CPM can be used both for cooling and heating, but basic LRM cannot be applied to heating. This paper presents an improved equivalent restraint method, ERM, which easily can be applied both for usage of heating and cooling for general structures. Restraint curves are given for two different infrastructures, one founded on frictional materials and another on rock. Such curves might be directly applied in design using LRM and ERM.

  • 6.
    Al-Gburi, Majid
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Yousif, Salim T
    Mosul University.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Simplified methods for crack risk analyses of early age concrete: Part 2: Restraint factors for typical case wall-on-slab2012In: Nordic Concrete Research, ISSN 0800-6377, Vol. 46, no 2, p. 39-56Article in journal (Refereed)
    Abstract [en]

    Existing restraint curves have been applied to the method of artificial neural networks (ANN) to model restraint in the wall for the typical structure wall-on-slab. It has been proven that ANN is capable of modeling the restraint with good accuracy. The usage of the neural network has been demonstrated to give a clear picture of the relative importance of the input parameters. Further, it is shown that the results from the neural network can be represented by a series of basic weight and response functions. Thus, the results can easily be made available to any engineer without use of complicated software.

  • 7.
    Ansell, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Malm, Richard
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Modelling of thermally induced cracking of a concrete buttress dam2008In: Nordic Concrete Research, ISSN 0800-6377, Vol. 38, p. 69-88Article in journal (Refereed)
    Abstract [en]

    Some of the larger hydropower dams in Sweden are buttress dams, consisting of up to 100 concrete monoliths formed by a front plate with a supporting buttress. Cracks have been observed in some dams, through the buttresses and at the base close to the rock foundation. The combined effects of restrained thermal displacements and loads caused by water are studied through finite element analysis. The results demonstrate the use of a non-linear material model and show that it is possible to follow the formation and propagation of the cracks. The analyses indicate that thermal stresses in combination with the loads caused by external water pressure are the reason for the cracking.

  • 8.
    Bagge, Niklas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Sas, Gabriel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Bernspång, Lars
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Carolin, Anders
    Trafikverket.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Full-Scale Test to Failure of a Prestressed Concrete Bridge in Kiruna2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 83-86Article in journal (Refereed)
    Abstract [en]

    To calibrate methods for condition assessment of prestressed concrete (PC) bridges, tests are planned for a 50 year old five-span bridge with a length of 121 m in Kiruna in northern Sweden. Both non-destructive and destructive full-scale tests will be performed. This paper summarises the test programme, which comprises evaluation of the structural behaviour of the bridge, the residual forces in the prestressed steel, methods for strengthening using carbon fibre reinforced polymers (CFRP) and the shear resistance of the bridge slab.

  • 9.
    Bagge, Niklas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Instrumentation and Full-Scale Test of a Post-Tensioned Concrete Bridge2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 51, p. 63-83Article in journal (Refereed)
    Abstract [en]

    To meet new demands, existing bridges might be in need for repair, upgrading or replacement. To assist such efforts a 55-year-old post-tensioned concrete bridge has been comprehensively tested to calibrate methods for assessing bridges more robustly. The programme included strengthening, with two systems based on carbon fibre reinforced polymers (CFRPs), failure loading of the bridge’s girders and slab, and determination of post-tension cables’ condition and the material behaviour. The complete test programme and related instrumentation are summarised, and some general results are presented. The measurements address several current uncertainties, thereby providing foundations for both assessing existing bridges’ condition more accurately and future research.

  • 10. Blanksvärd, Thomas
    et al.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Strengthening of concrete structures with cement based bonded composites2008In: Nordic Concrete Research, ISSN 0800-6377, no 2, p. 143-163Article in journal (Refereed)
  • 11.
    Boubitsas, Dimitrios
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Use of limestone in cement: The effect on strength and chloride transport in mortars2013In: Nordic Concrete Research, ISSN 0800-6377, no 47/1, p. 61-80Article in journal (Refereed)
    Abstract [en]

    This paper describes studies carried out to examine the influence_x000D_ on strength and chloride ingress when Portland cement is replaced_x000D_ with limestone filler. In the chloride ingress study both an_x000D_ accelerated method and field exposure measurements up to one_x000D_ year were employed. The results show that the method of_x000D_ measuring the resistance to chloride ingress can have a major_x000D_ influence on the assessment of the effect of different binders._x000D_ Further, the effect on chloride resistance, when replacing Portland_x000D_ cement with limestone filler is strongly dependent of the_x000D_ replacement ratio. The effect on compressive strength when_x000D_ replacing Portland cement with limestone filler is also strongly_x000D_ dependent of the replacement ratio.

  • 12.
    Bryne, Lars-Elof
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Laboratory testing of early age bond strength between concrete for shotcrete use and rock2013In: Nordic Concrete Research, ISSN 0800-6377, Vol. 47, p. 81-100Article in journal (Refereed)
    Abstract [en]

    Shotcrete(sprayed concrete) is, together with rock bolts, the most important material used for reinforcement in hard rock tunnelling. Sprayed concrete differs from ordinary concrete through the application technique and the addition of accelerators which give immediate stiffening. The bond between sprayed concrete and rock is one of the most important properties in the quality assessment of shotcreted concrete. During the very early age after spraying the physical properties of the concrete and the bond to the rockdepend on the accelerator and the micro structure that is formed. In this work a laboratory test method for measuring early bond strength for very young shotcrete is presented.

  • 13. Carlswärd, Jonas
    et al.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Avoiding undesirable end results of bonded steel fibre concrete overlays: observations from tests and theoretical calculations2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 49, p. 93-112Article in journal (Refereed)
    Abstract [en]

    Due to a high degree of damages and undesirable final results of bonded overlays, research has been conducted to develop recommendations on design and execution. Laboratory and half scale tests as well as theoretical analyses have been carried out including e. g. base and end restraint tests on overlays with various reinforcement, concrete qualities, substrate preparing and curing. Also, analytical and numerical calculations have been performed. Results reveal that the bond between overlay and substrate is the most critical parameter for a successful final result. Other key parameters are shrinkage and curing, while fibre and bar reinforcement generally proved to be less significant. Theoretical models work well on this case and will be further developed

  • 14. Carlswärd, Jonas
    et al.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Shrinkage cracking of thin concrete overlays2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 355-359Article in journal (Refereed)
    Abstract [en]

    Due to a high degree of damages and undesirable end results of bonded overlays, research is conducted to develop recommendations on design and execution. Laboratory and full scale tests as well as theoretical analyses have been carried out including e. g. base and end restraint tests on overlays with various reinforcement, concrete qualities, substrate preparing and curing. Moreover, analytical and numerical calculations have been performed. Results reveal that the e. g. bond between overlay and substrate is a critical parameter for a successful end result. Another key parameter is sufficient curing, while reinforcement generally proved to be less significant. Theoretical models works well on this structural situation and will be further developed.

  • 15.
    During, Otto
    et al.
    RISE - Research Institutes of Sweden, Built Environment, CBI Swedish Cement and Concrete Research Institute.
    Bhochhibhoya, Silu
    Univeristy of Twente, Netherlands.
    Kunar Maskey, Ramesh
    Kathmandu University, Nepal.
    Joshi, Rajendra
    Kathmandu University, Nepal.
    Rice Husk Resource for Energy and Cementitious Products with Low CO2 contributions2018In: Nordic Concrete Research, ISSN 0800-6377, Vol. 59, no 2, p. 45-58Article in journal (Other academic)
    Abstract [en]

    Rice Husk Ash (RHA) is a well-known supplementary cementitious materials (SCMs) that can be used for concrete with reduced CO

    2 contributions. In 2016, only Nepal produced 5.2 million tonnes rice that gave about 1.14 million tonnes rice husk. The rice husk can also be used directly in a cement kiln as a fuel. This study analysis the potential CO2 reductions from three scenarios and emphasis strengths, weaknesses, opportunities and treats in the production systems for initiate a decision process with possibilities to get an industry project financed from the green climate found. The highest CO2 benefits were from rice husk used in a cement kiln were half of the yearly rice husk production in Nepal could reduce the climate impact with 808000 tonnes CO2.

  • 16.
    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.

  • 17.
    Edrees, Tarek
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Semi-active structural control strategies2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 31-34Article in journal (Refereed)
    Abstract [en]

    The utilization of structural control systems to alleviate the responses of civil engineering structures, under the effects of dynamics loadings, has become a standard technology, while still there are numerous of current research approaches for advancing the effectiveness of these methodologies. It is important for successful application of smart structure to provide an effective control algorithm to compute the control forces to be applied on the building in order to reduce the external disturbances. The aim of this article is to provide a review of the control strategies to control the performance of semi-active systems utilized in civil engineering structures.

  • 18.
    Elfgren, Lennart
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Cederwall, Krister
    Fatigue strength of cable couplers in prestressed concrete beams1982In: Nordic Concrete Research, ISSN 0800-6377, Vol. 1, p. 5.1-5.14Article in journal (Refereed)
    Abstract [en]

    Fatigue tests have been carried out on ten prestressed concrete beams. Six of the beams were furnished with a cable coupler in the mid-span and four beams had no cable coupler. The uncoupled beams could in some cases sustain 9 times as many load cycles as the coupled beams. Some probable causes to the coupled beams lower fatigue strength are discussed in the paper.

  • 19.
    Emborg, Mats
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Bernander, Stig
    Temperature stresses in early age concrete due to hydration1984In: Nordic Concrete Research, ISSN 0800-6377, no 3, p. 28-48Article in journal (Refereed)
    Abstract [en]

    Theoretical models for the analysis of thermal induced stresses in massive concrete structures are presented. Laboratory tests are conducted in order to calibrate the theoretical models for different types of cement, concrete mixtures etc

  • 20.
    Emborg, Mats
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Simonsson, Peter
    Industrial concrete construction for a better economy and working environment: possibilities and obstacles with self compacting concrete2008In: Nordic Concrete Research, ISSN 0800-6377, no 2, p. 47-59Article in journal (Refereed)
    Abstract [en]

    The implementation of SCC together with new reinforcement and form techniques make it possible to increase the degree of industrialisation. It has been found in research at LTU that detailed planning and optimization of the building process, are essential utensils to successfully introduce such new techniques. However, also important is to address the technical issues hindering the marketing of SCC. Such issues are the robustness of the concrete and he surface quality. Thus, a discussion is given in the article on the optimization of robust SCC mixes and test results both from laboratory and building site as well as how criteria of SCC can be defined.

  • 21.
    Enckell, Merit
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    New Årsta Railway Bridge: A case study on the long-term Structural Health Monitoring with Fibre Optic Sensors2011In: Nordic Concrete Research, ISSN 0800-6377, no 2/2011, p. 123-142Article in journal (Refereed)
    Abstract [en]

    The New Årsta Railway Bridge was built in 2000-2005. The structure is a unique pre-stressed concrete girder bridge with slender and optimised design. Structural Health Monitoring System was installed on the bridge during construction. One characteristic span is mainly instrumented with several sensors and monitoring is still ongoing.This paper presents the Fibre Optic Sensor system including thermocouples; and their function. Observations, malfunctions and inconvenience during construction, testing and operation are collected, carefully documented and analysed. Strain and temperature data are collected from first casting up to date.Results are highlighted and conclusions are drawn. Recommendations are given, based on the experience gained so far. Furthermore, general, accumulated knowledge about monitoring is given.

  • 22.
    Fjellström, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Heat loss compensation for semi-adiabatic calorimetric tests2013In: Nordic Concrete Research, ISSN 0800-6377, Vol. 47, no 1, p. 39-60Article in journal (Refereed)
    Abstract [en]

    Heat of hydration has long been of importance since it affects the temperature levels within a concrete structure, and thus, potentially affects its durability. The only source of energy is the reaction between cement and water. This energy warms up the concrete sample and all the ambient materials. Therefore, in order to model these energies, the TSA (traditional semi-adiabat) setup is transformed into an associated sphere. By this, the temperature distribution and the energies within each layer of the TSA can be calculated. The sum of all energies gives the total heat of hydration. A refined model using a correction factor is introduced, which accounts for energies lost to the TSA setup materials. Results show that the effect of this factor cannot be disregarded, especially not for TSAs with low cooling factors.

  • 23.
    Fjellström, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Model for concrete strength development including strength reduction at elevated temperatures2012In: Nordic Concrete Research, ISSN 0800-6377, Vol. 45, no 1, p. 25-44Article in journal (Refereed)
    Abstract [en]

    When casting concrete structures, one of the most important properties is the concrete strength development. The need of actions on site is different at various stages of hardening, from the fresh concrete to the hardened concrete. The paper defines a model analysing maturity and associated strength growth within three important time periods. The model can be applied separately within each of these periods depending on test data available.It is shown in the paper that the temperature plays an important role on the strength development of concrete structures. The hydration rate increases with increased temperatures, which can be described by maturity functions. If the concrete temperature remains high, strength reduction at later ages usually occurs compared to hardening at lower temperature, which may be denoted strength reduction at elevated temperatures or cross over effects. Both these phenomena have been implemented in the model for strength growth presented in the paper. The functionality of the model is demonstrated by evaluation of laboratory tests for five concrete mixes and two types of cement.

  • 24. Fridh, Katja
    et al.
    Andersson, Ronny
    A model to calculate the CO2-uptake in a country’s concrete structures during service life and after2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, no 2, p. 443-446Article in journal (Refereed)
    Abstract [en]

    During the project ‘The CO2-cycle in cement and concrete’ an analytical model to quantify the CO2-uptake in a country a specified year was developed. That was accomplished by deriving a new model for the carbonation process and as input to that, measurements of carbonation in concrete indoors and studies of carbonation in crushed concrete were made. Through knowledge of the cement production each year, the distribution of the cement into different products and estimations of what concrete quality each product has, the total uptake for Sweden was calculated. For the year 2011 was the CO2-uptake calculated to 300 000 tons.

  • 25.
    Geiker, Mette Rica
    et al.
    Norwegian Univ Sci & Technol, Norway;Tech Univ Denmark, Denmark.
    De Weerdt, Klaartje
    Norwegian Univ Sci & Technol, Norway.
    Garzon, Sergio Ferreiro
    Cementir Holding SpA, Denmark.
    Jensen, Mads Monster
    Tech Univ Denmark, Denmark.
    Johannesson, Björn
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Michel, Alexander
    Tech Univ Denmark, Denmark.
    Screening of Low Clinker Binders, Compressive Strength and Chloride Ingress2017In: Nordic Concrete Research, ISSN 0800-6377, Vol. 57, no 2, p. 23-38Article in journal (Refereed)
    Abstract [en]

    This paper reports an initial screening of potential new binders for concrete with reduced CO2-emission. Mortars cured saturated for 90 days are compared with regard to a) compressive strength of mortars with similar water-to-binder ratio, and b) chloride ingress in similar design strength mortars exposed to seawater. The reference used was a binder composition typical for a Danish ready mixed concrete for aggressive environments and strength class C35/45. Based on the present investigation and assumptions up to around 15% reduction in CO2 emission from binder production might be obtained without compromising the 90 days compressive strength and resistance to chloride ingress in marine exposure by using selected alternative binders.

  • 26.
    Ghasemi, Yahya
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Particle Packing for Concrete Mix Design: Models vs. Reality2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 51, p. 85-94Article in journal (Refereed)
    Abstract [en]

    The packing density of aggregates is of great importance in concrete mix design as obtaining a higher packing density leads to less usage of cement paste which has technical, environmental and economic benefits. It is thus of interest to model particle packing correctly. Hence, in this study, packing densities of seven mixes of aggregate were attained in the laboratory using the loose packing method and were compared to values suggested by three models: 4C, Compressible Packing Model and Modified Toufar Model. Modified Toufar showed 1.72% mean difference from the laboratory values while CPM and 4C had mean differences of 1.79% and 1.84% respectively. In addition, it was found that some of the models are preferable in certain mixtures.

  • 27.
    Ghasemi, Yahya
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Johansson, Niklas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Particle packing of aggregates for concrete mix design: Models and methods2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 109-112Article in journal (Refereed)
    Abstract [en]

    An optimized aggregate particle packing density used as a base for concrete mix design provides economic, environmental and technical advantages. The particle packing density can be determined by many methods and predicted by different models. This paper reviews common packing and procedures and compares predictions of three common packing models to each other. It was found that the models tend to show different packing densities and percentage of ingredients for the same mixture. A test setup is proposed to determine the accuracy of each model’s prediction.

  • 28.
    Gram, Annika
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Silfwerbrand, Johan
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Applications for numerical simulation of self-compacting concrete2010In: Nordic Concrete Research, ISSN 0800-6377, Vol. 42, no 2, p. 143-154Article in journal (Other academic)
  • 29.
    Gram, Hans-erik
    et al.
    Cementa AB.
    Westerholm, Mikael
    Cementa AB.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Crushed fine aggregate for concrete production2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 113-117Article in journal (Refereed)
  • 30.
    Hallgren, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Kinnunen, Sven
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Punching Shear Tests on Circular High Strength Concrete Slabs without Shear Reinforcement1991In: Nordic Concrete Research, ISSN 0800-6377, no 10, p. 37-47Article in journal (Refereed)
  • 31.
    Hallgren, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Kinnunen, Sven
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Nylander, Birgitta
    Vägverket.
    Punching Shear Tests of Column Footings1998In: Nordic Concrete Research, ISSN 0800-6377, no 21, p. 1-22Article in journal (Refereed)
  • 32.
    Hansson, Håkan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Malm, Richard
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Non-linear Finite Element Analysis of Deep Penetration in Unreinforced and Reinforced Concrete2011In: Nordic Concrete Research, ISSN 0800-6377, Vol. 44, p. 87-107Article in journal (Refereed)
    Abstract [en]

    Penetration and perforation of concrete targets are studied by the use of numerical simulations to enhance the understanding of the penetration phenomenon. Comparisons were made with test results obtained for both reinforced and unreinforced 48.0 MPa normal strength concrete. The studied projectiles were made as generic models of penetrators for buried hardened target defeat. Varying impact velocities and angles for the penetrators were investigated. The simulations gave reasonable results for the different simulation cases, with the best results were obtained for reinforced concrete targets.

  • 33. Hedebratt, J
    et al.
    Silfwerbrand, Johan
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Lessons learned: Swedish design and construction of industrial concrete floors2012In: Nordic Concrete Research, ISSN 0800-6377, Vol. 45, p. 75-92Article in journal (Other academic)
  • 34.
    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)
  • 35.
    Hällmark, Robert
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Collin, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Concrete shear keys in prefabricated bridges with dry deck joints2011In: Nordic Concrete Research, ISSN 0800-6377, Vol. 2011, no 44Article in journal (Refereed)
    Abstract [en]

    A prefabricated concrete deck with dry joints between deck elements has been developed to make prefabricated bridges even more competitive. This type of bridge deck has been used on single span bridges in Sweden, and is now under development for multi span bridges. This paper describes how the deck system works. Results from laboratory tests of shear keys between deck elements are also presented together with an analysis comparing the predicted capacity with the measured failure load.

  • 36.
    Hösthagen, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Equivalent Restraint Method Correlated to Empirical Measurements2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 505-508Article in journal (Refereed)
    Abstract [en]

    The present study deals with the correlation between numerical models and empirical observations in newly cast concrete specimens. The model used is the equivalent restraint method, ERM, which is established from several local restraint method calculations, LRM. The csating of walls in a tunnel construction is investigated. Correlation between models and empirical measurements is established in three steps.

  • 37.
    Hösthagen, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Wallin, Kjell
    Projektengagemang i Stockholm AB.
    Stelmarcik, Marcin
    Thermal crack risk estimations for tunnel: equivalent restraint method correlated to empirical observations2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 49, p. 127-143Article in journal (Refereed)
    Abstract [en]

    The present study deals with the correlation between numerical models and empirical observations in newly cast concrete structures. The model used is the equivalent restraint method, ERM, which is established from several local restraint method calculations, LRM. The casting of walls and roof in a tunnel construction is investigated. Correlation between models and empirical measurements is established in three steps: 1) the restraint situation is analyzed; 2) the calculated temperature developments are compared to empirical temperature measurements to calibrate the models; and 3) calculated strain ratios are compared with observed crack patterns, and in general a good correlation is achieved

  • 38.
    Johansson, Niklas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Methods to optimize aggregate composition: evaluation by concrete experiments2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 201-204Article in journal (Refereed)
    Abstract [en]

    A proper mix design optimizes the environmental impact and the cost effectiveness of a concrete. A minimum cement paste content is desirable without deteriorate the concrete properties. Thus, cement paste content is dependent on the packing properties of the aggregates. Three different methods to optimize the aggregate composition have been evaluated by concrete tests: one curve fitting method and two particle packing methods. Crushed and natural aggregates have been tested at two different w/c ratios. The results show that the methods suggest very different aggregate compositions and they can´t handle fine crushed aggregates that consume a lot of mixing water.

  • 39.
    Johansson, Niklas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Methods to Optimize Aggregate Distribution: Evaluation by Concrete and Mortar Experiments2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 51, p. 145-157Article in journal (Refereed)
    Abstract [en]

    A proper mix design optimizes the environmental impact and the cost effectiveness of a concrete. A minimum cement paste content is desirable without deteriorate the concrete properties. The cement paste content is dependent on the packing properties of the aggregates and it of interest to estimate the packing correctly. Three methods to optimize the aggregate distribution have been evaluated by concrete tests for crushed and natural aggregates: one curve fitting method and two particle packing methods. It is shown that the methods suggest very different aggregate distributions for an optimum concrete mix and they can´t handle fine crushed aggregate that consumeings a lot of mixing water.

  • 40.
    Johansson, Niklas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Johansson, Peter
    Division of Building Materials, Lund University.
    Water Absorption in Concrete: Experiments and Modelling2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 469-472Article in journal (Refereed)
  • 41.
    Johansson-Selander, Anders
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Janz, Mårten
    Penetration profiles of water repellent agents in concrete as a function of time: determined with FTIR-spectrometer2010In: Nordic Concrete Research, ISSN 0800-6377, Vol. 41, no 1, p. 51-60Article in journal (Other academic)
  • 42.
    Jonasson, Jan-Erik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Measurement and modelling of strength and heat of hydration for young concrete2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 501-504Article in journal (Refereed)
    Abstract [en]

    Strength development and heat evolution at hydration are two of the most important properties when analysing concrete structures concerning young concrete. The present model for strength development is shown to properly predict the strength development for high early temperatures during hardening stage. The detemination of heat of hydration based on semi-adiabatic test has been refined with respect to the warming up the test equipment.

  • 43.
    Jonasson, Jan-Erik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilsson, Lars-Olof
    Lunds tekniska högskola, LTH.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Moisture and mechanical properties aimed for crack risk analyses if early age concrete2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 409-412Article in journal (Refereed)
    Abstract [en]

    Within the project Crack-Free-Con - Nordic coordination for sustainable construction by novel shrinkage modelling and user friendly Expert System - a collaborative project between research area of Building Material at LTH and Structural Engineering at LTU a comprehensive test program has been performed. The tests at LTH are concentrated on moisture related properties while the tests at LTU cover mechanical properties and stress development. At present the interesting work to combine the test results from the laboratories are in progress

  • 44.
    Lagerblad, Björn
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Bryne, Lars Elof
    Cement hydration and development of texture and bond at interfacial zone between hard rock and shotcrete2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, no 2, p. 263-266Article in journal (Refereed)
    Abstract [en]

    Sprayed concrete differs from ordinary concrete through application technique and addition of set accelerator that gives immediate stiffening. The alkali free set accelerator consists of sulphate and aluminate and forms an ettringite network that gives a stiff but not hard matrix. This work has investigated the interaction between the early ettringite matrix and the proper cement hydration and the development of the interfacial zone between concrete and rock. This has been correlated to the development of the bond strength.

  • 45.
    Lagerblad, Björn
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Cirera Riu, Jaume
    How to evaluate fillers from crushed rock aggregate for concrete production2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, no 2, p. 105-108Article in journal (Refereed)
    Abstract [en]

    In fresh concrete, the filler fraction (0-0.125 mm) is of vital importance for workability. With the use of superplasticizer, it is possible today to use quite large amount of fillers. This has made it possible to make self-compacting concrete and other special concretes. How to use the fillers and the amount of fillers depends on the size distribution and quality of the filler. Basically, the filler should be round and the distribution of filler and cement should be continuous. The size shall not overlap too much with that of the cement. Fillers from crushed rocks consist of minerals and the filler particles depend on the mineralogy and texture of the rock type. This work treats different methods, including paste rheology, to evaluate the quality of the filler fraction. By using good quality filler, it is possible to reduce the amount of cement in concrete

  • 46.
    Löfsjögård, Malin
    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).
    Proposal for Improvement of Road Lighting Design of Concrete Roads2007In: Nordic Concrete Research, ISSN 0800-6377, no 1-2/2006, p. 1-17Article in journal (Refereed)
  • 47.
    Magnusson, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Fibre reinforced concrete beams subjected to air blast loading2006In: Nordic Concrete Research, ISSN 0800-6377, no 35, p. 18-34Article in journal (Refereed)
    Abstract [en]

    This paper involves testing of steel fibre reinforced concrete(SFRC) beams subjected to static and dynamic loads. Thedynamic load was generated by a detonating explosive charge.The work focused upon studying the mechanical behaviour ofthe beams. The concrete compressive strength varied between36 MPa and 189 MPa with a fibre content of 1.0 percent byvolume. Two different fibre lengths having constant length-todiameterratio were employed. The experimental results indicatethat the toughness is reduced when increasing the compressivestrength and the dynamic strength is higher than thecorresponding static strength.

  • 48.
    Malm, Richard
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Full-scale test of an unreinforced concrete dome plug for the spent nuclear fuel repository2018In: Nordic Concrete Research, ISSN 0800-6377, Vol. 58, no 1, p. 55-75Article in journal (Refereed)
    Abstract [en]

    In the planned Swedish repository for spent nuclear fuel, plugs are designed to close the deposition tunnels. The outer part of these plugs consists of a concrete dome made with selfcompacting-concrete, designed to have low pH to reduce negative effects on the bentonite clay buffer. A full-scale test has been performed to evaluate the performance of the plug, to test the installation and to verify underlying design assumptions. In this paper, the behaviour of the concrete dome is evaluated based on measurements, from casting the concrete until it was subjected to 4 MPa hydrostatic water pressure.

  • 49.
    Mc Carthy, Richard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Is it possible to predict formwork pressure when using SCC?: A field study2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 49, no 1, p. 73-91Article in journal (Other academic)
    Abstract [en]

    In Sweden, the market share of cast-in-place Self-Compacting_x000D_ Concrete (SCC) is only around 10%. Uncertainty concerning_x000D_ formwork pressure is considered to be one of the most important_x000D_ factors explaining the slow progression. During construction of a_x000D_ 400 m long, 6 m high and 0.27 m thick prison wall in northern_x000D_ Sweden, SCC alone was used. The formwork used consisted of_x000D_ steel-framed panels, instrumented with flush-mounted pressure_x000D_ sensors. Each concrete batch was tested for air content, slumpflow,_x000D_ concrete and air temperature. Besides tests on torsional_x000D_ moment or torque, L-box, and V-funnel were carried out._x000D_ Relations between concrete properties, casting rate and time_x000D_ versus formwork pressure were investigated. The results_x000D_ confirmed that structural build-up of SCC has to be taken into_x000D_ account for predicting formwork pressure. The torsional moment_x000D_ was measured at three consecutive times at each casting and the_x000D_ time-dependent development of the torsional moment was_x000D_ subsequently used as indirect input in two simple formwork_x000D_ pressure methods that have been developed recently. The_x000D_ comparison between computed and measured formwork pressure_x000D_ shows that both these methods would be possible to use for_x000D_ predicting formwork pressure generated by SCC.

  • 50. Mc Carthy, Richard
    et al.
    Silfwerbrand, Johan
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    The Swedish user´s view of self-compacting concrete2011In: Nordic Concrete Research, ISSN 0800-6377, Vol. 44, no 2, p. 75-86Article in journal (Other academic)
12 1 - 50 of 97
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf