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  • 1.
    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.

  • 2.
    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.

  • 3.
    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.

  • 4.
    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.

  • 5.
    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.

  • 6. 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)
  • 7. 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

  • 8. 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.

  • 9.
    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.

  • 10.
    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.

  • 11.
    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

  • 12.
    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.

  • 13.
    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.

  • 14.
    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.

  • 15.
    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.

  • 16.
    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.

  • 17.
    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)
  • 18.
    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.

  • 19.
    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.

  • 20.
    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

  • 21.
    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.

  • 22.
    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.

  • 23.
    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)
  • 24.
    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.

  • 25.
    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

  • 26.
    Nilforoush, Rasoul
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    A Refined Model for Predicting Concrete-Related Failure Load of Tension Loaded Cast-in-Place Headed Anchors in Uncracked Concrete2019In: Nordic Concrete Research, ISSN 0800-6377, Vol. 60, no 1, p. 105-129Article in journal (Refereed)
    Abstract [en]

    Current theoretical models for predicting the concrete cone breakout capacity of tension loaded headed anchors do not consider the influence of member thickness, size of anchor head, and orthogonal surface reinforcement. In the present study, the influence of the aforementioned parameters was studied both numerically and experimentally. Both the numerical and experimental results showed that the tensile resistance of headed anchors increases by increasing the member thickness or if orthogonal surface reinforcement is present. In addition, the anchorage capacity further increases with increase of the anchor head size.

    The current model for predicting the concrete cone failure load of tension loaded headed anchors were refined and extended by incorporating three modification factors to account for the influence of the member thickness, size of anchor head, and orthogonal surface reinforcement. The accuracy of the proposed model was verified based on the results of 124 tests on single headed anchors from literature.

  • 27.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Upgrading the Haparanda Bridge: Unbonded Posttensioning2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 425-428Article in journal (Refereed)
    Abstract [en]

    The Haparanda Railway Bridge was upgraded for a higher load resistance in the summer of 2012. The slab of the 50 year old bridge was subjected to horizontal posttensioning and the railway administrators could thereby permit higher axle loads, 300 kN instead of the original 250 kN. The strengthening procedure was first examined in a laboratory pilot study and since the results were good, the method was applied on a real bridge. The posttensioning of the Haparanda Bridge reduced the strain in the tensile reinforcement substantially; all strains from a 215 kN/axle train were in fact counteracted.

  • 28.
    Nilimaa, Jonny
    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.
    Elfgren, Lennart
    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.
    Transversal post tensioning of RC trough bridges: laboratory tests2012In: Nordic Concrete Research, ISSN 0800-6377, Vol. 46, no 2, p. 57-74Article in journal (Refereed)
  • 29.
    Nilimaa, Jonny
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Häggström, Jens
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Bagge, Niklas
    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.
    Ohlsson, Ulf
    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.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Carolin, Anders
    Paulsson, Björn
    UIC, Trafikverket.
    Maintenance and Renewal of Concrete Rail Bridges: Results from EC project MAINLINE2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 25-28Article in journal (Refereed)
    Abstract [en]

    There is a need to extend the life and capacity of many existing railway bridges. One of the objects of the EC-FP7-Project MAINLINE, 2011-2014, is to facilitate this. Guidelines for assessment and strengthening methods are presented as well as case studies in which existing bridges are being studied in order to extend their life length. Case studies on bridges tested to failure in order to calibrate assessment methods are also presented. Fatigue is often a vital question. A Life Cycle Assessment Tool (LCAT) is being prepared to enable Infrastructure Managers to choose optimal maintenance strategies.

  • 30.
    Nilimaa, Jonny
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Hösthagen, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Thermal Crack Risk of Concrete Structures: Evaluation of Theoretical Models for Tunnels and Bridges2017In: Nordic Concrete Research, ISSN 0800-6377, Vol. 56, no 1, p. 55-69Article in journal (Refereed)
    Abstract [en]

    An approach for thermal crack risk estimations was introduced in the Swedish design guidelines BRO 94. The cracking occurs during the early hardening process because of the exothermic reactions between water and cement and often result in high repair costs and delayed construction. This paper studies and validates the inherent safety levels for one typical case of concrete structure. Three slab-frame structures were analysed and the original crack risk estimations were compared to the actual cracking and postcalculations were carried out, using actual parameters. This paper shows that walls with computed strain ratios over 70% were affected by thermal cracks.

  • 31.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Re-usage of Concrete Elements: To determine their new possible environment2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 229-232Article in journal (Refereed)
    Abstract [en]

    40% of the energy consumption in Sweden is used in the construction industry. Recycling – including re-usage, recycling and energy recovery – could possibly reduce this energy consumption. Re-usage gives the largest energy savings, evaluated by calculating the recycling potential. Designing for disassembly means planning how structures can easily be disassembled into original components and then recycled. Concrete elements must be designed, documented and assessedregarding reinforcement, cutting locations and degradation, respectively, for a safe reusage in new environments. A plan is designed for how to assess concrete elements and for which new environments they can be used in.

  • 32. Nilsson, Martin
    et al.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Partial coefficient for thermal cracking problems determined by a probabilistic method2003In: Nordic Concrete Research, ISSN 0800-6377, Vol. 27, p. 107-125Article in journal (Refereed)
    Abstract [en]

    The aim of this work is to calculate partial coefficients for thermal cracking problems of young concrete and to compare the results with the values stated in the Swedish building code for bridges, [1]. The code values are only based on experiences and logical reasoning, whereas the calculated values form a more theoretical base for their determination. The coefficients are calculated with a probabilistic method. Various different possible variations of the used variables have been studied showing the wide range of possible results depending on the input. However, with use of material properties and reasonable assumptions related to thermal cracking problems, fairly good agreement has been found between the stated values in the Swedish code [1] and the values obtained through the probabilistic method. The calculated values are based on many assumptions and assumed values and should therefor not be seen as what is right but rather more as an indication on the reasonableness of the values stated in the Swedish code. Further investigations, calculations and judgements should be performed before wider conclusions can be drawn.

  • 33.
    Nilsson, Martin
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Ohlsson, Ulf
    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.
    Effects of surface reinforcement on bearing capacity of concrete with anchor bolts2011In: Nordic Concrete Research, ISSN 0800-6377, Vol. 2011, no 44, p. 161-174Article in journal (Refereed)
    Abstract [en]

    66 tests of the influence of surface reinforcement on the tensile load capacity of cast-in fasteners have been carried through. In the tests threaded rods ∅30 mm with a ∅45 mm nut at the end were cast-in centrically in concrete slabs (1.2 m × 1.2 m × 0.3 m up to 2.2 m × 2.2 m × 0.6 m). The amount of surface reinforcement was varied from 0% up to about 1.2%. There is a considerable increase in the load capacity with surface reinforcement present. The increase depends on the geometry and the amount and placement of the reinforcement.

  • 34.
    Orosz, Katalin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Strengthening of Concrete with Carbon Fibre Reinforced Polymer (CFRP) Grids Bonded by Cementitious Binders2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 207-210Article in journal (Refereed)
    Abstract [en]

    Knowledge of the tensile behaviour of the strengthening material is important to estimate the shear capacity of the strengthened structure. In this paper, the tensile behaviour of externally bonded carbon fibre polymer (CFRP) grids has been studied. Bonding agent was either quasi-brittle polymer-modified mortar (PMM) or strain-hardening (“ductile”) mortar, instead of the typical epoxy resin. Uniaxial tensile and wedge-splitting tests were conducted to investigate the tensile-, and post-cracking behaviour, toughness, and ductility. The strain-hardening mortar enhanced both the load bearing- and in particular, the deformation capacity, surpassing the benefits of the PMM. The “ductile” mortar has also shifted the overall behaviour from brittle towards a more ductile failure.Keywords: Concrete, Strengthening, CFRP, Testing, Strain Hardening, Tensile Behaviour, Cracking, Brittleness, Deformation Capacity

  • 35.
    Orosz, Katalin
    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.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Fischer, Gregor
    Technical University of Denmark.
    Crack development and deformation behaviour of CFRP-reinforced mortars2013In: Nordic Concrete Research, ISSN 0800-6377, Vol. 48, p. 49-69Article in journal (Refereed)
    Abstract [en]

    This paper reports on a research study investigating CFRPreinforced mortars in uniaxial tension, as a strengthening material for concrete structures. The bare strengthening material was tested on dogbone specimens. Crack formation, crack development and the interaction between the grid and the mortar phase with varying geometrical parameters and mortar compositions have been investigated and evaluated. The use of engineered cementitious composites, exhibiting multiple cracking and enhanced pseudo-ductility in uniaxial tension, was found to result in an improved overall performance.

  • 36.
    Orosz, Katalin
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Fjellström, Peter
    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.
    Evaluation of the Linear Logarithmic Creep Model2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 417-420Article in journal (Refereed)
    Abstract [en]

    In order to make reliable predictions of thermal cracking risks in young concrete, modelling of the creep behaviour is important. The linear logarithmic creep model (LLM) has only been used to describe the creep behaviour of moisture-sealed concrete samples (basic creep). The aim of the present research is to check whether LLM could be also applied to drying creep. The results indicate that the LLM delivers good results for sealed but not for drying samples. Thus, refinement of the existing model (e.g., tri-linear instead of bi-linear in logarithmic time scale), or a new model is needed to account for the increase of creep due to on-going drying.

  • 37.
    Orosz, Katalin
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Fjellström, Peter
    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.
    Evaluation of Thermal Dilation and Autogenous Shrinkage at Sealed Conditions2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 299-302Article in journal (Refereed)
    Abstract [en]

    As known, load independent deformations are of large importance in structural analysis, e. g. when estimating elongations, restraint stresses, or pre-stressing forces. Two models to describe thermal dilation (TD) and autogenous shrinkage (AS) have been evaluated, for a broader range of w/C ratios and cements types than before. In Model I, AS is determined solely based on the maturity model and TD incorporates two TD coefficients (TDC). In Model II, AS is dependent on both the maturity model and a separate temperature adjustment factor, while TDC is constant. For the more rapid-hardening cement, Model I did not give satisfactory results, whereas the usefulness of Model II to describe both AS and TD has shown to be limited, suggesting that a new model is needed.

  • 38.
    Persson, Martin
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Ohlsson, Ulf
    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.
    Bridge deck concrete overlays: full scale studies2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 49, p. 163-180Article in journal (Refereed)
    Abstract [en]

    Concrete overlays on bridge decks are thought to be more durable when comparing with the more common solution with asphalt. Of interest is to evaluate the concrete overlay regarding traffic and shrinkage/temperature induced stresses. In a pilot study nondestructive test systems were evaluated with focus on detecting hidden defects, (e.g. debonding), that may have induced identified surface cracks. Furthermore, calibration of material parameters for a similar composite slab was done using finite element technique and compared with experimental studies in laboratory. Good agreement was found between numerical and experimental results. This will serve as an input for future bridge FE-models.

  • 39.
    Persson, Martin
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Ohlsson, Ulf
    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.
    Bridge deck concrete overlays: full scale studies and theoretical analysis2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 509-512Article in journal (Refereed)
    Abstract [en]

    Concrete overlays on bridge decks are thought to be more durable when comparing with the more common solution with asphalt. Of interest is to evaluate the concrete overlay regarding traffic and shrinkage/temperature induced stresses. In a pilot study nondestructive test systems were evaluated with focus on detecting hidden defects, (e.g. debonding), that may have induced identified surface cracks. Furthermore, calibration of material parameters for a similar composite slab was done using finite element technique and compared with experimental studies in laboratory. Good agreement was found between numerical and experimental results. This will serve as an input for future bridge FE-models.

  • 40.
    Plos, Mario
    et al.
    Chalmers University of Technology.
    Gylltoft, Kent
    Chalmers University of Technology.
    Lundgren, Karin
    Chalmers University of Technology.
    Cervenka, Jan
    Cervenka Consulting, Praha.
    Herwig, Andrin
    EPFL, Lausanne.
    Brühwiler, Eugen
    EPFL, Lausanne.
    Thelandersson, Sven
    Lund University of Technology.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Rosell, Ebbe
    Swedish Road Administration, Borlänge.
    Structural assessment of concrete bridges2008In: Nordic Concrete Research, ISSN 0800-6377, no 2, p. 99-111Article in journal (Refereed)
    Abstract [en]

    The paper summarizes the work on concrete bridges performed in the EU project Sustainable Bridges. The work provides enhanced assessment methods that are able to provide higher load-carrying capacities and longer fatigue lives for exixixting concrete railway bridges. The work is also presented in a Guideleine available at www.sustainablebridges.net

  • 41.
    Popescu, Cosmin
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Dăescu, Cosmin
    Politechnica University of Timisoara.
    Tamás, Nagy-György
    Politechnica University of Timisoara.
    Sas, Gabriel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Disturbed regions in dapped-end beams: numerical simulations of strengthening techniques2013In: Nordic Concrete Research, ISSN 0800-6377, Vol. 48, no 2, p. 14-26Article in journal (Refereed)
    Abstract [en]

    This paper investigates the effectiveness of strengthening reinforced concrete (RC) dapped-end beams using carbon fiber reinforced polymers (CFRP). Parametric studies are performed by means of numerical simulations in which several types of composite materials as well as their orientation are combined. The primary objectives of this research were the evaluation of the strengthening systems in terms of ultimate capacities and the failure modes involved. Results show that only some of them provide significant load bearing capacity increase. The observed failure modes ranged from a sudden failure up to the desired progressive failure of the strengthening system.

  • 42.
    Popescu, Cosmin
    et al.
    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.
    The Development of an Experimental Program through Design of Experiments and FEM Analysis: A Preliminary Study2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 51, p. 29-42Article in journal (Refereed)
    Abstract [en]

    This paper presents an experimental test setup which allows investigation of the structural behaviour for axially loaded concrete walls with openings. The test matrix was developed with the help of design of experiments technique. A two level factorial experiment has been designed resulting in a total of nine wall specimens. Previous research has shown that the ultimate capacity of concrete walls is dependent on the boundary conditions. Therefore, a new test-rig was proposed and designed to work according to the imposed conditions. Nonlinear simulations calibrated on a previous experimental program were used to obtain the reaction forces.

  • 43.
    Popescu, Cosmin
    et al.
    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.
    Täljsten, Björn
    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.
    Experimental Program for Axially Loaded RC Walls with Openings Strengthened by FRP2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 285-288Article in journal (Refereed)
    Abstract [en]

    The presence of a new opening will decrease the axial capacity, thus, requiring upgrading. Satisfactory results were found when FRP was placed in the vicinity of the openings, being capable to restore the initial structural capacity. However, despite the considerable research carried out, there are still important research gaps that need to be further investigated. In this paper an experimental program aimed to study the influence of opening size and the strengthening pattern for RC walls will be presented. To achieve this aim, a two-level factorial experiment has been designed resulting in a total of nine wall specimens.

  • 44. Puurula, Arto
    et al.
    Enochsson, Ola
    Thun, Håkan
    Nordin, Håkan
    Täljsten, Björn
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Paulsson, Björn
    Banverket.
    Olofsson, Jan
    Skanska.
    Full-scale test to failure of a strengthened reinforced concrete bridge: calibration of assessment models for load-bearing capacities of existing bridges2008In: Nordic Concrete Research, ISSN 0800-6377, no 2, p. 131-142Article in journal (Refereed)
    Abstract [en]

    A reinforced concrete railway trough bridge has been strengthened and loaded to failure. The aim was to test and calibrate methods developed in the European Research Project "Sustainable Bridges" regarding: (a) condition appraisal and inspection, (b) load carrying capacity analysis, (c) monitoring and (d) strengthening of existing bridges. The tested methods proved to be useful and to give accurate predictions. A failure in combined shear, bending and torsion was reached for an applied mid span load of 11,7 MN. This was well predicted by enhanced methods but 20 to 50 % higher than ultimate load evaluated according to predictions based on common codes and models.

  • 45.
    Ronin, Vladimir
    et al.
    EMC Development AB.
    Emborg, Mats
    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.
    Self-Healing Performance and Microstructure Aspects of Concrete Using Energetically Modified Cement with a High Volume of Pozzolans2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 51, p. 131-144Article in journal (Refereed)
    Abstract [en]

    Self-healing can increase the lifetime and durability of concrete structures. The self-healing properties of concrete made with Energetically Modified Cement (EMC), which has a pozzolan content of up to 70%, have been investigated. In such concretes, pozzolanic reactions within the cement cause the gradual formation of fresh C-S-H gel, which seals cracks as they form. The self-healing of small EMC concrete samples was tested in a laboratory, and field observations of an EMC concrete highway pavement were made. The EMC concrete exhibited fewer cracks than conventional concrete, and was observed to self-heal cracks with widths of up to 0.2 mm.

  • 46.
    Ronin, Vladimir
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering. EMC Cement B.V..
    Jonasson, Jan-Erik
    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.
    Self-Healing Concrete: Results with Energetically Modified Cement (EMC)2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 57-60Article in journal (Refereed)
    Abstract [en]

    Energetically Modified cement (EMC) containing up to 70 % of pozzolans have been tested to have the ability to deliver long term pozzolanic reactions (calcium oxide + wateer + silicon dioxide) leading to the formation of additional amounts of C-H-S gel. This can fill voids and cracks of widths up to 0,2 mm, up to twice the crack width that usually can be healed. EMC is Portland cement mechanically activated in a process with a pozzolan, silica sand or blast furnace slag. The process was discovered 1992 at Luleå University of Technology and has been further developed since then.

  • 47.
    Sandström, Thomas
    et al.
    WSP Group.
    Fridh, Katja
    Division of Building Materials, Lund University.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hassanzadeh, Manouchehr
    Vattenfall Research & Development.
    The influence of temperature on water absorption in concrete during freezing2012In: Nordic Concrete Research, ISSN 0800-6377, Vol. 45, no 1, p. 45-58Article in journal (Refereed)
  • 48.
    Sas, Gabriel
    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.
    Enochsson, Ola
    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.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Puurula, Arto
    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.
    Flexural-shear failure of a full scale tested RC bridge strengthened with NSM CFRP: Shear capacity analysis2011In: Nordic Concrete Research, ISSN 0800-6377, Vol. 2/2011, no 44, p. 189-206Article in journal (Refereed)
  • 49.
    Sayahi, Faez
    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.
    Plastic Shrinkage Cracking in Concrete: State of the Art2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 51, p. 95-110Article in journal (Refereed)
    Abstract [en]

    As plastic shrinkage cracking can dramatically reduce the durability of a concrete member and causes considerable repair costs annually, a comprehensive understanding of the mechanism of the phenomenon is essential to prevent these damages in future. In this paper, an overview is given on the mechanism of plastic shrinkage crack formation and the status of present technologies avoiding the cracking are reported through referring to previously conducted research and observations.

  • 50.
    Sayahi, Faez
    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.
    Plastic shrinkage cracking: research in Scandinavia2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 351-354Article in journal (Refereed)
    Abstract [en]

    As plastic shrinkage cracking still causes considerable repair costs annually, an understanding of the phenomenon is essential to prevent these damages in the future. In the paper, the status of present technology to avoid cracking is briefly reported through referring to research conducted in Scandinavia. In addition, on-going activities at LTU are described and future plan is demonstrated. Thus, experiments are performed on concrete slabs cast in rectangular moulds and cured at some variations of environmental conditions. The results will be used to find critical evaporation rate at very early age.

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