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  • 51.
    Emborg, Mats
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jongeling, Rogier
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Olofsson, Thomas
    Dorbell, Thorbjörn
    Innovative construction with cast in place concrete using product models2004In: Concrete Structures: The Challenge of Creativity. Proceedings of FIB symposium on Concrete Structures, 2004, p. 220-221Conference paper (Refereed)
  • 52.
    Emborg, Mats
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Noghabai, Keivan
    Luleå tekniska universitet.
    Groth, Patrik
    Luleå tekniska universitet.
    Fibre-reinforced high performance concrete1996In: Proceedings: Nordic Concrete Research Meeting, Espoo, Finland 1996, Oslo: Norsk Betongforening , 1996, p. 54-55Conference paper (Refereed)
  • 53.
    Emborg, Mats
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Rådberg, Gunnar
    Thun, Håkan
    Undvikande av temperatursprickor i prefabricerade betongelement1997Report (Other academic)
  • 54.
    Emborg, Mats
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Simonsson, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Increasing the market share of SCC2010In: Concrete Plant International, ISSN 1437-9023, no 3, p. 218-222Article in journal (Other academic)
  • 55.
    Emborg, Mats
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Simonsson, Peter
    Industrial casting of bridges with new production methods: the importance of a robust self compacting concrete2008In: Proceedings, Nordic Concrete Research, Bºalsta, Sweden: XXth Symposium on Nordic Concrete Research & Development ... The current proceedings contain 90 summaries of oral poster presentations] / [ed] Johan Silfwerbrand, Oslo: Norsk Betongforening , 2008, p. 170-171Conference paper (Refereed)
  • 56.
    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.

  • 57.
    Emborg, Mats
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Simonsson, Peter
    Carlswärd, Jonas
    Nilsson, Martin
    Industrial casting of bridges combining new production methods materials: like a robust SCC, utilizing lean construction principle2007In: Proceedings of the 5th International RILEM Symposium on Self-Compacting Concrete: SCC2007 / [ed] G De Schutter; V Boel, Bagneux, France: Magnel Laboratory for Concrete Research, Ghent University , 2007, Vol. 1, p. 485-490Conference paper (Refereed)
  • 58.
    Emborg, Mats
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Westman, Gustaf
    Luleå tekniska universitet.
    Bernander, Stig
    Assessment of the risk of thermal cracking in hardening high-strength concrete1993In: Utilization of High Strength Concrete : Proceedings: Symposium in Lillehammer, Norway / [ed] Ivar Holand, Oslo: Norsk Betongforening , 1993, p. 1054-1061Conference paper (Refereed)
  • 59. Enochsson, Ola
    et al.
    Sabourova, Natalia
    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.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Gruvvägsbron I Kiruna: Deformationskapacitet2011Report (Other academic)
    Abstract [sv]

    En bedömning har gjorts av hur stora deformationer Gruvvägsbron i Kiruna kan klara med bibehållen bärförmåga. I projektet har mätningar av brons beteende vid statisk och dynamisk belastning utförts under vinter- respektive sommarförhållanden. Mätningarna har utvärderats och analyserats med FEMprogram för att kunna bedöma brons styvhet och deformationskapacitet. Syftet har varit att undersöka hur mycket bron klarar av i stödförändringar på grund av gruvdriften. Preliminära gränsvärden för stödförändringar har tagits fram.Brons statiska funktionssätt är tillfredsställande. Enligt hittillsvarande mätningar (t o m dec 2010) har endast små markrörelser ägt rum vilket inte nämnvärt påverkar brons funktion.Brons dynamiska funktionssätt är också tillfredsställande. Uppmätta egenmoder och egenfrekvenser är normala för denna typ av förspänd balkbro. Bron är förhållandevis styv och de analytiska och numeriska beräkningar(FEM-analyser) som gjorts tyder på att den har förhållandevis begränsad deformationskapacitet. Vi bedömer att bron klarar följande lokala deformationsskillnad mellan två närliggande pelare: (a) i horisontalled ca 40mm och (b) i vertikalled ca 80 mm. Om tillåtna värden sätts till hälften av de möjliga erhålls:Tillåten differens för rörelse(a) i tvärled mellan en pelares över- och underkant till = ca 20 mm(b) i höjdled mellan två intilliggande stöd till = ca 40 mmVärdena kan komma att revideras (förfinas) i samband med att resultat blir tillgängliga från fortsatta mätningar och observationer av brons beteende.Några markrörelser av betydelse inträffade inte mellan november 2006 och 2008, men under 2009 och 2010 har rörelser skett med några mm. Brons längdändring på grund av temperaturvariationer är dock betydligt större. Bronär ca 3 – 4 cm längre på sommaren än på vintern. Eftersom markrörelserna förväntas bli betydligt större i samband med att gruvans brytningsfront närmar sig bron försågs brons pelare under sommaren2010 med en anordning rdning så att deras läge kan justeras om markrörelserna blirojämna.

  • 60.
    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.

  • 61.
    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.

  • 62.
    Ghasemi, Yahya
    et al.
    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.
    A method for obtaining optimum packing of aggregates for concrete at the onset of flow2017In: Proceedings of the 23rd Nordic Concrete Research Symposium, Oslo, Norway: Nordic Concrete Federation , 2017, p. 361-365Conference paper (Refereed)
    Abstract [en]

    Particle packing models have been studied extensively during past decades and led to development of some complex and relatively accurate predictions of packing of granular materials. While the models are capable of calculating the packing density for different volumetric share of constitutes, the concept of optimum packing remains unclear. The study aims to define optimum packing based on particle packing theory and excess water layer theory .The approach makes it also possible to calculate amount of paste that is required to put a concrete mixture at the onset of flow. Some pilot tests conducted in the laboratory showed good agreement with calculated data.

  • 63.
    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.

  • 64.
    Ghasemi, Yahya
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Lulea university of technology.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Lulea university of technology.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    A theoretical study on optimal packing in mortar and paste2019In: Advances in Cement Research, ISSN 0951-7197, E-ISSN 1751-7605Article in journal (Refereed)
    Abstract [en]

    Packing density of particles is regarded as a key factor affecting workability of cementitious mixtures. While the value can be easily measured, and several models exist for estimating the parameter, no generally accepted definition exist for the optimal packing. Current study aims at exploring the concept of optimal packing in mortars and paste using particle packing and excess water layer theories. A semiempirical method is used for calculating water demand of mixtures based on their specific surface area. The approach allows for estimating optimal packing considering water demand and water to cement ratio of mixtures in addition to packing density. 

  • 65.
    Ghasemi, Yahya
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Lulea university of technology.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Betongindustri AB, Stockholm, Sweden.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Effect of water film thickness on the flow in conventional mortars and concrete2019In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 52, no 3, article id 62Article in journal (Refereed)
    Abstract [en]

    Mortar and concrete can be divided into two phases of solids and water where water fills the voids between the grains and also coats the surface of particles. The current study investigates the influence of the thickness of coating water on flow spread of mortars and concretes. The article aims at correlating consistency of concretes to consistency of mortars. It was found that the flow behavior of granular mixtures can be directly related to the average water film thickness that envelops the particles. The concept was tested on mortar and concrete mixtures with different cement types, aggregate grading, aggregate shape, fineness and proportioning; proving water film thickness to be the most critical parameter affecting the flow. The results of the study indicate the possibility of predicting the flowability of mixtures by knowing the enveloping water film thickness. In addition, the relation between flowability of mixtures measured in different sizes of slump cone is explored to enable translating flow of mortars measured in mini-slump cone to flow of concrete obtained from Abram’s cone.

  • 66.
    Ghasemi, Yahya
    et al.
    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.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Exploring the relation between the flow of mortar and specific surface area of its constituents2019In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 211, p. 492-501Article in journal (Refereed)
    Abstract [en]

    Mortars can be studied as mixtures of solid and flowable phases. The volume of the flowable phase required for deformation depends on the solid phase surface area according to excess layer theories. This paper examines the relation between the specific surface area of constituents in mortars and their flow. The flowable phase volume was divided by the solid phase surface area to obtain the layer thickness surrounding the surface of the particles. The results suggested that the amount of water and paste needed to ensure flow could be estimated from the packing density and specific surface area of the particles.

  • 67.
    Ghasemi, Yahya
    et al.
    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.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Quantification of the shape of particles for calculating specific surface area of powders2016In: RILEM publication S.A.R.L, Denmark, 2016, Vol. 115, p. 31-41Conference paper (Refereed)
    Abstract [en]

    The concepts of particle packing and water/paste layer theory are commonly used for basis of concrete mix design models. While particle packing insists on achieving fewer voids in aggregate matrix by adding fine aggregate, water/paste layer theories state that increasing the amount of fines will lead to higher water demand since the specific surface area of particles will increase. In order to calculate the thickness of excess paste, it is essential to quantify the shape of particles. However, there are uncertainties regarding how the various shape parameters would affect the packing and specific surface, mainly because up to now many of the shape parameters are not yet clearly defined and there are no commonly accepted methods for their measurement. In addition, the term “shape” needs to be defined, some research suggest that for obtaining an appropriate shape factor several parameters need to be measured e.g. flakiness, elongation, sphericity, convexity etc. The paper aims to derive a shape factor based on variation of packing from the packing of ideal spheres with the same particle size distribution as the studied aggregate and to apply the shape factor to calculate an approximate specific surface area value.

  • 68.
    Ghasemi, Yahya
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Mats, Emborg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Estimation of specific surface area of particles based on size distribution curve2018In: Magazine of Concrete Research, ISSN 0024-9831, E-ISSN 1751-763X, Vol. 70, no 10, p. 533-540Article in journal (Refereed)
    Abstract [en]

    Workability in the fresh state is one of the most important factors in design and production of concrete and can be related to the water demand of the mixture, which in addition to other factors is a function of the particle shape of aggregates and binders and their specific surface area. While it is known that the shape of fine particles has a significant effect on the water demand, there are uncertainties regarding how the various shape parameters would affect the specific surface area, mainly because up to now many of the shape parameters have not yet been clearly defined and there are no commonly accepted methods for their measurement and/or estimation. In this research, the actual particle shapes were replaced with regular convex polyhedrons to calculate the total specific surface area using the size distribution curves of the samples. The obtained results indicate that while, in some cases, the assumption of a spherical particle shape leads to an acceptable estimation of the specific surface area when compared with Blaine test results, the specific surface area of powders with more angular particles could be calculated more accurately with the assumption of a polyhedron shape rather than a sphere.

  • 69.
    Ghasemi, Yahya
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Rajczakowska, Magdalena
    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.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Shape-dependent calculation of specific surface area of aggregates versus X-ray microtomography2020In: Magazine of Concrete Research, ISSN 0024-9831, E-ISSN 1751-763X, Vol. 72, no 2, p. 88-96Article in journal (Refereed)
    Abstract [en]

    The specific surface area (SSA) of constituents in a concrete mixture has a significant effect on its workability in fresh state. Excess layer theories relate the SSA to the flow behaviour of mixtures and can be used as part of an approach to mix design. However, measurement of SSA is complex and includes several issues, and thus is commonly replaced by mathematical estimation of the parameter. The mathematical approximation of surface area is based on the assumption of a spherical shape for the particles, which leads to failure of taking into account the effect of shape and the square–cube law. The article explores the possibility of replacing the assumption of a spherical shape with that of Platonic solids as the representative shape to account for the angularity of aggregates. The calculation was conducted based on information on the particle size distribution (PSD) obtained from dry sieving method. A calculated surface area on the assumption of a dodecahedron shape for natural aggregates and a cubical shape for crushed aggregates showed good agreement with SSA measurements conducted by X-ray microtomography. Furthermore, the effect of changes in PSD on the accuracy of the approach was also studied. It was found that the estimated value of SSA was improved in comparison with the traditional way of calculation on the assumption of a spherical shape.

  • 70.
    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)
  • 71.
    Gylltoft, Kent
    et al.
    Luleå tekniska universitet.
    Emborg, Mats
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Utmattningshållfasthet för betongkonstruktioner: Rapport från tre pågående forskningsprojekt vid Tekniska högskolan i Luleå1983In: Väg- och Vattenbyggaren, ISSN 0042-2177, no 10, p. 17-20Article in journal (Other (popular science, discussion, etc.))
  • 72.
    Hatem, Mohammed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Pusch, Roland
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Packing theory for natural and crushed aggregate to obtain the best mix of aggregate: research and development2012In: Proceedings of World Academy of Science, Engineering and Technology, ISSN 2010-376X, E-ISSN 2070-3740, Vol. 67, p. 819-825Article in journal (Refereed)
    Abstract [en]

    Concrete performance is strongly affected by the particle packing degree since it determines the distribution of the cementitious component and the interaction of mineral particles. By using packing theory designers will be able to select optimal aggregate materials for preparing concrete with low cement content, which is beneficial from the point of cost. Optimum particle packing implies minimizing porosity and thereby reducing the amount of cement paste needed to fill the voids between the aggregate particles, taking also the rheology of the concrete into consideration. For reaching good fluidity superplasticizers are required. The results from pilot tests at Luleå University of Technology (LTU) show various forms of the proposed theoretical models, and the empirical approach taken in the study seems to provide a safer basis for developing new, improved packing models.

  • 73.
    Hatem, Mohammed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Pusch, Roland
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Emborg, Mats
    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.
    Alireza, Pourbakhtiar
    Talc-based concrete for sealing borehole optimized by using particle packing theory2013In: Journal of Civil Engineering and Architecture, ISSN 1934-7359, E-ISSN 1934-7367, Vol. 7, no 4, p. 440-455Article in journal (Refereed)
    Abstract [en]

    The paper describes assessment of the performance of cement-poor concreteson the basis of packing theory. The concretes are intended for sealing segments of deep boreholes and have a small amount of cement for minimizing the mutual chemical impact on the contacting clay seals. The composition is examined by application of packing theory with respect to the cement/aggregate ratio and the gradation of the aggregate material which is crushed quartzite for providing high internal friction after maturation, as well as to talc added for fluidity and to the small amount of cement. Low porosity and micro-structural stability must be guaranteed for very long periods of time. The study exemplifies how packing theory assist designers in selecting optimal proportions of the various components. Optimum particle packing implies minimizing the porosity and thereby reducing the amount of cement paste needed to fill the voids between the aggregate particles. The use of talc as inorganic super-plasticizer since ordinary organic additives for reaching high fluidity at casting are undesirable, and since talc reacts with cement and provides high strength in along-term perspective.

  • 74.
    Hatem, Mohammed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Pusch, Roland
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical 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.
    Pourbakhtiar, Alireza
    Proportioning of cement-based grout for sealing fractured rock-use of packing models2013In: Engineering, ISSN 1947-3931, E-ISSN 1947-394X, Vol. 5, no 10, p. 765-774Article in journal (Refereed)
    Abstract [en]

    Fractured, very permeable rock hosting repositories for radioactive waste will require grouting. New grout types of possible use where long-term performance is needed should have a small amount of cement for minimizing the increase in porosity that will follow from the ultimate dissolution and erosion of this component. They have to be low-viscous and gain strength early after injection and packing theory can assist designers in selecting suitable proportions of various grout components. Optimum particle packing means that the porosity is at minimum and that the amount of cement paste needed to fill the voids between aggregate particles is very small. Low porosity and microstructural stability must be guaranteed for long periods of time. Organic additives for reaching high fluidity cannot be used since they can give off colloids that carry released radionuclides and talc can be an alternative superplasticizer. Low-pH cement reacts with talc to give high strength with time while Portland cement gives early but limited strengthening. The clay mineral palygorskite can be used for early gelation because of its thixotropic properties. Once forced into the rock fractures or channels in soil it stiffens and serves as a filter that prevents fine particles to migrate through it be lost. However, its hydrophilic potential is too high to give the grout a high density and high strength. According to the experiments carried out most of the investigated grouts are injectable in fractures with apertures down to 100 μm.

  • 75.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Westman, Gustaf
    Luleå tekniska universitet.
    Emborg, Mats
    Jonasson, Jan-Erik
    Bernander, Stig
    Hardening technology for concrete structures1997In: Advanced design of concrete structures: [papers presented at the Symposium on Advanced Design of Concrete Structures, held in Chalmers University of Technology in Göteborg, Sweden on June 12 - 14, 1997] / [ed] Kent Gylltoft, Barcelona: International Center for Numerical Methods in Engineering (CIMNE), 1997, p. 313-318Conference paper (Refereed)
  • 76.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Westman, Gustaf
    Luleå tekniska universitet.
    Emborg, Mats
    Jonasson, Jan-Erik
    Bernander, Stig
    Härdningsstyrning av betongkonstruktioner1996In: Byggforskning : Byggforskningsrådets tidning för en bättre byggd miljö, ISSN 1102-3686, no 3, p. 38-39Article in journal (Other (popular science, discussion, etc.))
  • 77.
    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.

  • 78.
    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

  • 79.
    Hösthagen, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. anders.hosthagen@ltu.se.
    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 Fire Engineering.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Thermal Crack Risk Estimations of Concrete Walls: Temperature and Strain Measurements Correlated to the Equivalent Restraint Method2017In: Proceedings of the 23rd Nordic Concrete Research Symposium, Oslo, Norway: Nordic Concrete Federation , 2017Conference paper (Refereed)
    Abstract [en]

     Self-induced non-elastic deformations in hardening concrete, caused by restrained volume changes due to thermal dilatation and moisture deformations, often leads to cracking. In crack risk analyses, determination of the degree of restraint is vital. One model to estimate the restraint and calculate the thermal crack risk is the Equivalent Restraint Method, ERM. The method has previously been analyzed but needs to be further examined and validated. Recordings of tunnel sections were performed and compared to calculated values by ERM. Satisfying correlation between theoretically estimated and observed temperatures, strains and time of through cracking was achieve which is promising for future implementation and testing of the method.

  • 80.
    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.

  • 81.
    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.

  • 82. Jonasson, Jan-Erik
    et al.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Modelling of temperature and shrinkage induced cracking risks in young concrete2009In: Proceedings of abstracts: Comportement et Evaluation des Ouvrages Spéciaux. Fissuration Retrait (Ceos.fr). International workshop on Control of cracking in R.C. structures: a major step towards serviceability, 2009, p. 31-Conference paper (Other academic)
    Abstract [en]

    Control of thermal and shrinkage cracking in hardening concrete is of great importance to ensure desired service life and function of concrete constructions. Making reliable stress estimations, and thereby conclusions about cracking risks caused by temperature movements and shrinkage involves advanced modelling of material properties and structural restraint. Cracking of concrete during the hardening phase must be avoided in order to minimize the risk of durability problems in the future, such as corrosion risk of the reinforcement, water tightness and damages according to frost. Estimation of the risk of early age cracking requires knowledge of the combined effects from temperature development and mechanical behaviour during the hydration. Applications of the present model using the computer program ConTeSt Pro demonstrates that it can be used to decide what measures to be taken to minimize the risk of cracking during the hardening phase for concrete structures. One example of estimated temperatures and cracking risks is shown in Figure 1.Figure 1 Estimated temperatures and cracking risks for the walls of the concrete arch of the Svinesund bridge between Sweden and Norway. The arch was built by the technique of climbing form work

  • 83. Jonasson, Jan-Erik
    et al.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Bernander, Stig
    Temperatur, mognadsutveckling och egenspänningar i ung betong1994In: Betonghandbok. Arbetsutförande: projektering och byggande, Solna: Svensk byggtjänst , 1994, 2Chapter in book (Other (popular science, discussion, etc.))
  • 84. Jonasson, Jan-Erik
    et al.
    Emborg, Mats
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Wallin, Kjell
    Projektengagemang AB.
    How to build crack-free durable concrete structures: concrete hardening technology including modelling of shrinkage, creep and temperature of young concrete and its influence on durability and lifetime2009In: ISLECI 2009: The 4th International Symposium on Lifetime Engineering of Civil Infrastructure / [ed] Xianyan Zhou; Ayaho Miyamoto; Sang-Ho Lee; Yan Xiao, Central South University of Forestry and Technology, China , 2009Conference paper (Refereed)
    Abstract [en]

    Control of thermal and shrinkage cracking in hardening concrete is of great importance to ensure desired service life and function of concrete infrastructures. Making reliable stress estimations, and thereby conclusions about cracking risks caused by temperature movements and shrinkage involves advanced modelling of material properties and structural restraint. The paper presents the main outline of a model for description of material properties needed. Special focus is given to a creep model denoted LLM (Linear Logarithmic Model), which is shown to be robust, easy to use, and capable to extrapolate short-term test into long-term effects. Applications of the presented model using the computer program ConTeSt Pro demonstrates that it can be used to decide what measures to be taken to minimize the risk of cracking during the hardening phase for concrete structures.

  • 85.
    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.

  • 86.
    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

  • 87. Jonasson, Jan-Erik
    et al.
    Wallin, Kjell
    Emborg, Mats
    Gram, Annika
    Saleh, Iad
    Nilsson, Martin
    Larsson, Mårten
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Handbok med sprickriskbedömning inklusive åtgärder för betongkonstruktioner2001In: Bygg & Teknik, ISSN 0281-658X, Vol. 93, no 7, p. 16-20Article in journal (Other (popular science, discussion, etc.))
  • 88. Jonasson, Jan-Erik
    et al.
    Wallin, Kjell
    Emborg, Mats
    Gram, Annika
    Saleh, Iad
    Nilsson, Martin
    Larsson, Mårten
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Temperatursprickor i betongkonstruktioner: handbok med diagram för sprickriskbedömning inklusive åtgärder för några vanliga typfall. Del D och E2001Report (Other academic)
    Abstract [sv]

    Föreliggande handbok är framtagen i ett SBUF-projekt med Kjell Wallin, Peab som projektledare. Projektet har genomförts i nära samarbete mellan Peab Sverige AB och Luleå tekniska universitet. Arbetet har inneburit att ett stort antal datorberäkningar har genomförts, och de redovisas i diagramform i denna handbok. Resultaten avses att användas att fylla i en blankett i ett Excel-ark. Syftet är att för typfallet vägg-på-platta ska handboken ge underlag för sprickriskbedömning och i förekommande fall ange vilka typåtgärder som ska sättas in. Avsikten är därvid att man inte ska behöva göra några externa beräkningar, men användaren har full frihet att själv ta fram temperaturen eller tvångssituationen på godtyckligt annat sätt. Handboksmetodiken avser en fortsättning på det som i Bronormen (Bro 94, bilaga 9-5) kallas metod 2, och den redovisade kompletteringen innefattar främst att erforderliga åtgärder (kylning och/eller värmning) för det valda typfallet inkluderas.

  • 89.
    Jongeling, Rogier
    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.
    Asp, Martin
    Olofsson, Thomas
    Modelling and simulation of cast in place concrete construction using N-dimensions2005Report (Other academic)
    Abstract [en]

    Product models have long been theoretical models within international research communities, but are now starting to be adapted in the construction industry. Product models are data models that can contain both product and process data, such as geometry and planning data. Their current use in construction is mainly limited to 3D graphics, but product models have many more than three dimensions. In this research project we developed and applied different dimensions of product models beyond their common, but limited, use in 3D. Development and implementation efforts in the project are mainly driven by the interests from a ready-mixed concrete supplier. Product modelling systems imply an object oriented approach to cast in place concrete construction, which is not object oriented as a result of the nature of the product. Product models that are used in the design process differ from models that are used for production simulations. These, and other conditions, pose a number of challenges. However, product models offer also a number of opportunities to cast in place concrete construction. Products and processes can be simulated virtually for example, thereby facilitating the decision-making process regarding the application of new or existing technologies that can improve the construction process. Product models can also be used to link or integrate product data, such as material specifications, casting sequences, etc. Based on these, mainly theoretically identified, possibilities and constraints, a number of dimensions of product models are developed and applied in practice to different case study projects. The following model dimensions are explored in the project:Traditional 2D drawings and documents are partly generated from 3D models and hyperlinked to these models. Various types of 3D models from different disciplines are created by using file-based data transfers and a collaborative client-server environment. Multiple production plannings are linked to 3D models resulting in 4D models. 5D cost estimation is developed by linking different 3D models to cost estimation hierarchies. Model use and configuration of material parameters by a ready-mixed concrete supplier provides an additional dimension to the use of product models.The different dimensions illustrate on the one hand the support for new and existing products and processes for cast in place concrete construction and show on the other hand the potential of product model use beyond 3D graphics. Advantages and possibilities can be identified for the ready- mixed concrete supplier in the different model dimensions and we believe that other actors in construction can do the same. When actors have identified benefits of product modelling for their own business process they might be more willing to participate in shared product model use in search of benefits for the project team as a whole.

  • 90.
    Jongeling, Rogier
    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.
    Olofsson, Thomas
    nD modelling in the development of cast in place concrete structures2005In: Electronic journal of information technology in construction, ISSN 1403-6835, E-ISSN 1400-6529, Vol. 10, no 4, p. 27-41Article in journal (Refereed)
    Abstract [en]

    The Swedish IT-stomme (IT-structure) project is a two year research project, which is aimed at applying product models in practice and developing modelling tools for cast in place concrete structures. Implementations and applications discussed in this paper are mainly driven by the interests from a ready mixed concrete supplier who identified product modelling as a threat and as an opportunity for its business process. A number of product model dimensions is discussed that result from combining different software applications. An example of a potential nth dimension of product model development and use is given, in addition to a product model's 2nd, 3rd, 4th and 5th dimension. The nth dimension is illustrated by integrating a product model with results from a program used to calculate the optimal drying process for concrete slabs. This paper concludes by discussing main challenges for the uptake of product models in practice in relation to findings and efforts from the IT-stomme project.

  • 91.
    Jongeling, Rogier
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Olofsson, Thomas
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Modeling cast in place concrete construction alternatives with 4D CAD2004In: Proceedings of the 5th European Conference of Product and Process Modelling in the Building and Construction Industry / [ed] Attila Dikbas; Raimar Scherer, Taylor and Francis Group , 2004, p. 109-116Conference paper (Refereed)
    Abstract [en]

    This paper presents the results from a 4D modeling study in which 4D CAD was used to compare two different construction methods for a cast in place concrete structure. Evaluating construction alternatives in a virtual environment is considered to be an effective and cost efficient way to introduce and evaluate innovative construction processes and products. Results from the study show the potential of using multiple virtual prototypes, but also show limitations regarding required modeling effort and evaluation of results. Im-provements are suggested that facilitate and partly automate the 4D modeling process. Evaluation of the out-come of 4D models can be improved by extending the graphical outcome of the modeling process with a vari-ety of analyses. Research and development is needed to quantify results from 4D models, in order to allow comparison of construction alternatives on a range of different criteria.

  • 92.
    Jongeling, Rogier
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Olofsson, Thomas
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Product modelling for industrialized cast in place concrete structures2004In: Designing, managing and supporting construction projects through innovation and IT solutions: proceedings of the World IT Conference for Design and Construction, INCITE 2004, Langkawi, Malaysia, 18-21 February 2004 / [ed] Peter Brondon; Heng Li; Noridah Shaffii; Qiping Shen, Kuala Lumpur: Construction Industry Development Board Malaysia , 2004, p. 103-110Conference paper (Refereed)
  • 93.
    Larsson, Johan
    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.
    A study of the future for concrete bridge construction in Sweden2011In: Nordic Concrete Research: Proceedings of the XXI Nordic Concrete Symposium, Hämeenlinna, Finland 2011, Oslo: The Nordic Concrete Federation , 2011, p. 533-536Conference paper (Refereed)
  • 94.
    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.

  • 95.
    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.
    Validation of the Swedish Crack Risk Estimation Models2017In: Proceedings of the 23rd Nordic Concrete Research Symposium: Aalborg, Denmark, 21 - 23 August 2017, Oslo: Nordic Concrete Federation , 2017, p. 321-324Conference paper (Refereed)
    Abstract [en]

    Thermal cracking may occur during the early hardening process of concrete as a result of the exothermic reactions between water and cement. An approach for thermal crack risk estimation and prevention was introduced in the Swedish design guidelines BRO 94. This paper studies and validates the current safety levels existing concrete structures. Three slab-frame structures were analysed and the preliminary crack risk estimations were compared to the actual cracking and post-estimations were carried out, using actual parameters. This paper shows that all the studied walls with a strain ratio over 70% were affected by thermal cracks.

  • 96. Nilsson, Martin
    et al.
    Emborg, Mats
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Wallin, Kjell
    Sprickrisker i gjutfogar belastade med tvångsspänningar1998In: Bygg & Teknik, ISSN 0281-658X, no 7, p. 24-26Article in journal (Other (popular science, discussion, etc.))
  • 97.
    Nilsson, Martin
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Wallin, Kjell
    Emborg, Mats
    Bernander, Stig
    Elfgren, Lennart
    Crack prevention in walls and slabs: the influence of restraint1999In: Innovation in concrete structures: design and construction: design and construction ; proceedings of the international conference held at the University of Dundee, Scotland, UK on 8-10 September 1999 / [ed] Ravindra K. Dhir; M. Roderick Jones, London: Thomas Telford Ltd , 1999, p. 461-471Conference paper (Refereed)
  • 98.
    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.
    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.
    Fastenings (anchor bolts) in concrete structures: influence of surface reinforcement2012In: Concrete Structures for Sustainable Community: proceedings of the International FIB Symposium 2012, Stockholm, Sweden, 11 - 14 June 2012 / [ed] Dirch H. Bager; Johan Silfwerbrand, Stockholm: Swedish Concrete Association , 2012, p. 419-422Conference paper (Refereed)
    Abstract [en]

    Tests have been carried out to study the influence of surface reinforcement on the load bearing capacity of cast-in headed bars. In 66 tests, rods with a diameter of Φ30 mm and a Φ45 mm nut at the end, were cast-in place centrically in concrete slabs. Width, length and thickness of the slabs varied from 1.2 m × 1.2 m × 0.3 m up to 2.2 m × 2.2 m × 0.6 m. The top reinforcement varied from 0% to about 1.2% (Φ 16 #100). A considerable increase in the load-bearing capacity was noted. The increase depends on the geometry and the amount and placement of the reinforcement. A numerical model to evaluate the influence is proposed.

  • 99.
    Olofsson, Thomas
    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.
    Feasibility study of field force automation in the Swedish construction sector2004In: Electronic journal of information technology in construction, ISSN 1403-6835, E-ISSN 1400-6529, Vol. 9, no Paper 2004/20, p. 297-311Article in journal (Refereed)
    Abstract [en]

    Field Force Automation (FFA) is a generic term for mobile applications used in real-time support of orders, scheduling, supervising and reporting in the field. The result from in-depth interviews with people in the construction, the facility management and the supply industry is presented with the purpose to answer the following questions. (1) Where can FFA system be applied in the construction sector? (2) What is the economic impact of FFA systems? (3) How should FFA systems be introduced in specific operations? According to the results from interviews and ROI estimates, FFA can significantly increase the productivity of many construction related field operations through real time planning support, work allocation and follow-up provided that the technical solutions are adapted to the end user. The benefits are reduced lead times, more efficient use of resources in the field and enhanced quality of work.

  • 100.
    Olofsson, Thomas
    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.
    Isaksson, Lennart
    Nilsson, Klas
    Opportunities of mobile technology: field force automation2004In: Designing, managing and supporting construction projects through innovation and IT solutions: proceedings of the World IT Conference for Design and Construction, INCITE 2004, Langkawi, Malaysia, 18-21 February 2004 / [ed] Peter Brondon; Heng Li; Noridah Shaffii; Qiping Shen, Kuala Lumpur: Construction Industry Development Board Malaysia , 2004, p. 111-120Conference paper (Refereed)
123 51 - 100 of 130
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