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Visar resultat 1 - 5 av 9 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Hardening concrete : measurments and evaluation of non-elastic deformation and associated restraint stresses

    Författare :Hans Hedlund; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Structural Engineering; Konstruktionsteknik;

    Sammanfattning : If a structural member of hardening concrete is restrained to some degree against expansion and contraction during the heating phase of the hydration process and the subsequent contraction phase, stresses will be induced. The issue of primary interest is whether or not these induced stresses will lead to cracking. LÄS MER

  3. 2. Stresses in high performance concrete due to temperature and moisture variations at early ages

    Författare :Hans Hedlund; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Structural Engineering; Konstruktionsteknik;

    Sammanfattning : This thesis presents results from laboratory tests and numerical analyses of stress states in concrete structures arising from volume changes due to temperature and shrinkage during hydration. The laboratory tests presented here deal with: the determination of heat transfer coefficients for cooling pipes measurements of self-desiccation and shrinkage under sealed conditions deformation measurements under temperature and moisture changes and measurements of stress development during hardening for a fully restrained structural member. LÄS MER

  4. 3. Electrified Integrated Kinetic Energy Storage

    Författare :Magnus Hedlund; Hans Bernhoff; Markus Mueller; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; flywheel energy storage; magnetic bearings; carbon composite; Engineering Science with specialization in Science of Electricity; Teknisk fysik med inriktning mot elektricitetslära;

    Sammanfattning : The electric car is a technically efficient driveline, although it is demanding in terms of the primary energy source. Most trips are below 50 km and the mean power required for maintaining speed is quite low, but the system has to be able to both provide long range and high maximum power for acceleration. LÄS MER

  5. 4. Early age autogenous deformation and cracking of cementitious materials – Implications on strengthening of concrete

    Författare :Katalin Orosz; Andrzej Cwirzen; Hans Hedlund; Andrzej Garbacz; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; concrete; mortar; strengthening; composites; shrinkage; autogenous deformation; alkali activated materials; alkali activated slag; Structural Engineering; Konstruktionsteknik;

    Sammanfattning : .... LÄS MER

  7. 5. Self-Healing Concrete

    Författare :Magdalena Rajczakowska; Andrzej Cwirzen; Karin Habermehl-Cwirzen; Hans Hedlund; Erik Schlangen; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; cementitious materials; self-healing; exposure; fly ash; calcite; C-S-H; cracking; Byggmaterial; Building Materials;

    Sammanfattning : Concrete is a brittle material prone to cracking due to its low tensile strength. Crack repairs are not only expensive and time-consuming but also increase the carbon footprint. Designing a novel concrete material possessing the ability to self-repair cracks would enhance its sustainability. LÄS MER