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  • 1.
    Babaahmadi, Arezou
    et al.
    RISE - Research Institutes of Sweden, Built Environment, CBI Swedish Cement and Concrete Research Institute. Chalmers University of Technology, Sweden.
    Tang, Luping
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB. Chalmers University of Technology, Sweden.
    Abbas, Zareen
    University of Gothenburg, Sweden.
    Zack, Thomas
    University of Gothenburg, Sweden.
    Mårtensson, Per
    Swedish Nuclear Fuel and Waste Management Company, Sweden.
    Development of an electro-chemical accelerated ageing method for leaching of calcium from cementitious materials2015In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 49, no 1-2, p. 705-718Article in journal (Refereed)
    Abstract [en]

    To facilitate the long term durability predictions of nuclear waste repositories, acceleration methods enhancing calcium leaching process from cementitious materials are needed, even though mechanisms not necessarily comparable to those predominant in a natural leaching process may be developed. In the previously published acceleration methods the samples are very small, which limits further physical or mechanical tests. In this paper, a new acceleration method based on electro-chemical migration is presented. The method although not driven with the same kinetics as in natural leaching, was designed in such a way that unnecessarily destructive by-effects could be minimized while promoting a higher leaching rate for a sample size suitable for further testing the mechanical and physical properties. It is shown that approximately 1 × 106C of electrical charge per paste specimen of size Ø50 × 75 mm (approximately 230 g) is required to leach out the total amount of Portlandite. The chemical and mineralogical properties of leached samples are characterized by various techniques. It is concluded that aged samples are comparable to those leached in a natural leaching process as both are characterized by a layered system comprising an unaltered core delineated by total dissolution of Portlandite followed by a progressive decalcification of the calcium silicate hydrate gel.

  • 2. Bissonnette, B.
    et al.
    Courard, L.
    Beushausen, H.
    Fowler, D.
    Silfwerbrand, Johan
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Trevino, M.
    Vaysburd, A.
    Recommendations for the repair, the lining or the strengthening of concrete slabs or pavements with bonded cement-based material overlays2013In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 46, no 3, p. 481-494Article in journal (Refereed)
    Abstract [en]

    The recommendations presented in this publication are inspired by the State of the Art Report edited by the RILEM Technical Committee TC 193 RLS Bonded cement-based material overlays for the repair, the lining or the strengthening of slabs and pavements. The objective is to lay out all the practical aspects to be considered in the design of concrete overlay.bonded concrete overlay process, assessment of the existing structure, surface preparation, overlay materials, design methods, construction procedure and quality control/assurance system, and maintenance.

  • 3.
    Boubitsas, Dimitrios
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB. Lund University, Sweden.
    Tang, Luping
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB. Chalmers University of Technology, Sweden.
    The influence of reinforcement steel surface condition on initiation of chloride induced corrosion2015In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 48, no 8, p. 2641-2658Article in journal (Refereed)
    Abstract [en]

    This paper describes a part of the work in the development of a "standard" test method for determining chloride threshold values required to initiate corrosion on reinforcement in concrete. The prerequisites of the test set-up are that the test conditions should be reasonably comparable to those in service and the test method should be fairly reproducible and as rapid as possible concerning the slow diffusion nature of the investigated phenomenon. This paper presents the results from a study on the influence of steel bar surface condition on chloride induced corrosion. Various electrochemical techniques were employed in the study to monitor the corrosion behaviour of the embedded bars with three different surface conditions. It is shown that the steel surface condition has a strong effect on the corrosion initiation of reinforcement in concrete, and can likely be the most decisive parameter attributing to the variability in the reported chloride threshold values.

  • 4.
    Edwards, Ylva
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Tasdemir, Yuksel
    Energy saving and environmental friendly wax concept for polymer modified mastic asphalt2010In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 43, no 1(S), p. 123-131Article in journal (Refereed)
  • 5. Girhammar, Ulf Arne
    et al.
    Källsner, Bo
    SP- Sveriges Tekniska Forskningsinstitut, Trätek.
    Analysis of influence of imperfections on stiffness of fully anchored light-frame timber shear walls—elastic model2009In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 42, no 3, p. 321-337Article in journal (Refereed)
    Abstract [en]

    In order to stabilize light-frame timber buildings against horizontal loads, the diaphragm or in-plane action of roofs, floors and walls is often used. This paper deals with the influence of imperfections such as gaps and uplift on the horizontal displacement of fully anchored shear walls. The significance of analyzing the effects of imperfections is evident when evaluating the stiffness of shear walls; tests of walls show that the horizontal displacement is underestimated in calculations using the stiffness of sheathing-to-framing joints as obtained from experiments. Also, in real structures where hold-downs are used according to the elastic design method, the influence of gaps and uplift should be included in order to obtain realistic displacements in the serviceability limit state. A new elastic model for the analysis, based on linear elastic behaviour of the mechanical sheathing-to-framing joints, is presented and the equations for the stiffness and the deflection versus the number of segments in the wall are derived. The fully anchored condition for the shear walls are modelled by applying a diagonal load to the wall. Three types of imperfections are evaluated: gaps at all studs, a gap only at the trailing stud, and gaps at all studs, except at the trailing stud. It is shown that the effect of imperfections on the stiffness of the wall in the initial stage is considerable. Depending on the distribution of the gaps and the number of segments included in the shear wall, the displacement of the shear wall is increased several times compared to that of a fully anchored shear wall with no gaps; e.g. for a single segment wall more than three times. However, for walls with more than six to ten segments, the effect of imperfections can be neglected. Finally, the theoretical model is experimentally verified.

  • 6. Groot, Caspar
    et al.
    Lindqvist, Jan Erik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    RILEM TC 203-RHM: Repair mortars for historic masonry: Performance requirements for renders and plasters2012In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 45, no 9, p. 1277–1285-Article in journal (Refereed)
    Abstract [en]

    This article gives a summary of functional_x000D_ and performance requirements for renders and plasters_x000D_ for historic masonry (design, execution and maintenance)._x000D_ Specific attention has been paid to degradation_x000D_ effects, such as caused by salt crystallization and_x000D_ freeze–thaw cycling. Traditional as well as designed_x000D_ prefab mortars are considered for repair intervention.

  • 7. Hedebratt, J
    et al.
    Silfwerbrand, Johan
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Full-scale test of a pile supported steel fibre concrete slab2014In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 47, no 4, p. 647-666Article in journal (Refereed)
    Abstract [en]

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

  • 8. Hughes, JJ
    et al.
    Lindqvist, Jan Erik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    RILEM TC 203-RHM: Repair mortars for historic masonry: The role of mortar in masonry: an introduction to requirements for the design of repair mortars2012In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 45, no 9, p. 1287–1294-Article in journal (Refereed)
    Abstract [en]

    Mortar has been in use for many thousands of years and is integral to most masonry construction. Its use is widespread in every culture where masonry is constructed. It is present in the majority of the global built cultural heritage, and is therefore a major consideration in building conservation. The effective design of a mortar for repairing masonry depends on a clear understanding of its function. The main functional uses of mortar in masonry are classified as bedding, pointing, grout, render, plaster, flooring and mortars for surface repairs. The requirements that each type of mortar must meet in service depend on its environmental exposure and its role in the masonry element that it is found within (e.g. issues such as historic authenticity, aesthetics, resistance to moisture ingress, structural integrity, and service life). Technical requirements such as adhesion, strength, elasticity, water and vapour transmittance, drying behaviour, thermal dilatation, ability to deal with salt contamination and freeze-thaw cycling, and its aesthetic properties can be quantified. Mortar properties can be adjusted by varying ingredients and their proportions, to meet the differing technical requirements.

  • 9. Jansson, Anette
    et al.
    Flansbjer, Mathias
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Löfgren, Ingemar
    Lundgren, Karin
    Gylltoft, Kent
    Experimental investigation of surface crack initiation, propagation and tension stiffening in self-compacting steel–fibre-reinforced concrete2012In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 45, no 8, p. 1127-43Article in journal (Refereed)
    Abstract [en]

    To investigate crack initiation and propagation in reinforced, self-compacting, steel–fibre-reinforced concrete (SCSFRC) members, tie elements were tested in tension. Strain and surface crack formation were monitored with an optical strain measurement system based on digital image correlation. In addition, to capture the softening behaviour (s–w) of the material, uni-axial tension testing was performed on SCSFRC cylinders. The results show that, with the optical strain measurement system, it was possible to detect different cracking modes and to follow the crack growth. It was especially of interest to recognize that high fibre amounts tend to change a sudden opening of a crack (as in non-fibrous concrete) into a more stable procedure. It was found that, for a given crack width, the SCSFRC specimens exhibited a noticeably higher tension stiffening than the specimens without fibres. Moreover, at a given load, the crack widths decreased by as much as 65% for the SCSFRC specimens with a nominal fibre content of 1%. For the uni-axial tension tests the results showed that with higher fibre content, for this type of fibre and concrete, both the peak stress and the residual tensile stress were increased. Additionally, it was noted for both specimen types that the scatter in fibre distribution decreased with increasing fibre content.

  • 10.
    Jansson, Robert
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research.
    Boström, Lars
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research.
    Factors influencing fire spalling of self compacting concrete2013In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 46, no 10, p. 1683-1694Article in journal (Refereed)
  • 11.
    Jena, Naresh K.
    et al.
    KTH Royal Institute of Technology, Sweden.
    Lyne, Åsa L.
    RISE - Research Institutes of Sweden, Built Environment, CBI Swedish Cement and Concrete Research Institute.
    Arul Murugan, N. Arul
    KTH Royal Institute of Technology, Sweden.
    Ågren, Hans
    KTH Royal Institute of Technology, Sweden.
    Birgisson, Björn
    RISE - Research Institutes of Sweden, Built Environment, CBI Swedish Cement and Concrete Research Institute. Texas A&M University, USA.
    Atomic level simulations of the interaction of asphaltene with quartz surfaces: role of chemical modifications and aqueous environment2017In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 50, no 1, article id 99Article in journal (Refereed)
    Abstract [en]

    Understanding the properties of bitumen and its interaction with mineral aggregates is crucial for future strategies to improve roads and highways. Knowledge of basic molecular and electronic structures of bitumen, one out of the two main components of asphalt, poses a major step towards achieving such a goal. In the present work we employ atomistic simulation techniques to study the interaction of asphaltenes, a major constituent of bitumen, with quartz surfaces. As an effective means to tune adhesion or cohesion properties of asphaltenes and mineral surfaces, we propose chemical modification of the pristine asphaltene structure. By the choice of substituent and site of substitution we find that adhesion between the asphaltene molecule and the quartz surface can easily be improved at the same time as the cohesive interaction between the asphaltene units is reduced, while other substituents may lead to the opposite effect. We also provide insight at the molecular level into how water molecules affect interactions between asphaltenes and quartz. Our approach emphasizes a future role for advanced atomistic modeling to understand the properties of bitumen and suggest further improvements.

  • 12. Kargol, M A
    et al.
    Mueller, Urs
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Properties and performance of silane: blended cement systems2013In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 46, no 9, p. 1429-1439Article in journal (Refereed)
    Abstract [en]

    The paper presents the results of a study dealing with the performance of water repellents on hardened blended cement pastes. Since on the European market Portland cement does not play the dominant role anymore and due to the new national and European policies concerning Greenhouse Gases and sustainability, cement manufacturers produce more and more blended cements (CEM II-CEM V). Nevertheless, the majority of experience concerning the efficacy of water repellents is gained from Portland cement; therefore knowledge in regard to the interactions of blended cement with water repellent agent is minimal. Two silane-based products were applied on 'fresh' and carbonated cement substrates containing limestone, fly ash, slag and trass, and were investigated in terms of their functionality. The evaluation of the treatments' performance and effectiveness were assessed using various laboratory measurements. Hydrophobicity, water absorption, colour changes and the penetration depth of silanes into the substrate were evaluated before and after artificial aging experiments. Moreover, the outdoor weathering test was performed to shed light on treated surface appearance in a 'real' outdoor environment. The results showed that surface wettability was independent on water ingress or colour variations, especially for cement specimens artificially aged by accelerated carbonation. Cement pastes containing slag and trass seemed to more distinctly affect the water repellents' surface performance.

  • 13. Khayat, K H
    et al.
    Omran, A F
    Field-oriented test methods to evaluate structural build-up at rest of flowable mortar and concrete2012In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 45, no 10, p. 1547-1564Article in journal (Refereed)
    Abstract [en]

    Thixotropy of flowable mortar and concrete is an important property that affects stability and form pressure characteristics. The increase in thixotropy can reduce lateral pressure on formwork systems. On the other hand, low thixotropy or a continuous casting is required to eliminate the formation of weak interface between lifts in multilayer casting. Thixotropy can be assessed by determining the rate of structural build-up at rest, which necessitates the use of simple and robust test methods to be quantified. Five field-oriented test methods that can be used for the determination of structural build-up at rest of mortar and concrete are proposed in this paper in an attempt to select a reliable field-oriented test. This includes the inclined plane (IP), portable vane (PV), undisturbed slump spread (USS), cone penetration (CP), and K-slump test methods. The repeatability of these test methods was determined four times using two concrete-equivalent mortars and two self-consolidating concretes (SCC) of different thixotropy levels. The IP, PV, and USS tests showed relative error (RE) values of 0.5-37 %. The CP test was successfully used to determine structural build-up of mortar; however, it was difficult to assess the thixotropy of concrete. The K-slump test exhibited a RE, less than 12 % for SCC mixtures with low thixotropy, but up to 76 % for highly thixotropic SCC. Good correlations were established among the various structural build-up indices determined from the proposed test methods and those determined by rheometric tests using various concrete.

  • 14.
    Källsner, Bo
    et al.
    SP- Sveriges Tekniska Forskningsinstitut, Trätek.
    Girhammar, Ulf Arne
    Analysis of fully anchored light-frame timber shear walls—elastic model2009In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 42, no 3, p. 301-320Article in journal (Refereed)
    Abstract [en]

    In order to stabilize light-framed timber buildings against lateral loads, the diaphragm action of roofs, floors and walls is often used. This paper deals with an elastic analysis model for fully anchored sheathed wood frame shear walls. The model is based on the assumption of a linear elastic load-slip relation for the sheathing-to-framing joints. Only static loads are considered. The basic structural behaviour and assumptions for the elastic model are elucidated. Formulas for the load-bearing capacity and the deformation of the shear walls in the ultimate and serviceability limit states, respectively, are derived. Both a discrete point description and a continuous flow per unit length modelling of the fasteners are discussed. Also, the forces and displacements of the fasteners and sheathing are derived. The effect of different patterns and spacing of the fasteners on the capacity and displacement of the wall is illustrated. The influence of flexible framing members and shear deformations in the sheets, and also the effect of vertical loads on the shear wall, both with respect to tilting and second order effects, on the horizontal load-bearing capacity and displacement are evaluated. The stress distribution and the reaction forces at the ends of the different framing members are derived. The elastic model is experimentally verified and an illustrative example is given.

  • 15.
    Lindqvist, Jan Erik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Rilem TC 203-RHM: Repair mortars for historic masonry.: Testing of hardened mortars, a process of questioning and interpreting2009In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 48, no 7, p. 853-865Article in journal (Refereed)
  • 16.
    Lindqvist, Jan-Erik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Bygg och Mekanik.
    Sandström, Matz
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Bygg och Mekanik.
    Quantitative analysis of historical mortars using optical microscopy.2000In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 33, no 234, p. 612-617Article in journal (Other academic)
  • 17. Lundgren, Karin
    et al.
    Tahersamsi, Mohammad
    Tests on anchorage of naturally corroded reinforcement in concrete2014In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 48, no 7, p. 2009-2022Article in journal (Refereed)
    Abstract [en]

    Many studies on the structural effects of corrosion in reinforcement have been conducted. However, most of them are based on artificially corroded test specimens. Thus, the knowledge available entails one major uncertainty, i.e. whether the results are reliable enough to be used for naturally corroded structures. The purpose of this study was to develop a test method and carry out experiments on naturally corroded specimens taken from an existing structure to investigate the anchorage capacity. Beam specimens were taken from the edge beams of a bridge at repair. The specimens showed corrosion-induced damage to a varying extent from no sign of corrosion to extensive cracking and spalling of the concrete cover. A four-point bending test indirectly supported by suspension hangers was chosen. The beams were strengthened with transverse reinforcement around the suspension hangers to avoid premature failure. Eight successful tests were carried out; in all these tests, diagonal shear cracks preceded a splitting induced pull-out failure; i.e. anchorage failure was achieved as intended. The results showed around 10 % lower capacity for the corroded specimens than for the reference ones. The average bond stress in the anchorage zone was estimated based on the applied load and available anchorage length. The stress was about 16 % lower in the beams with corrosion cracks, and 9 % lower in the beams with cover spalling compared to the reference specimens; there was also a larger variation among the damaged specimens than for the reference specimens. The results extend our knowledge concerning the structural behaviour of corroded reinforced concrete structures during field conditions.

  • 18.
    Luping, Tang
    et al.
    Brandteknik, material (BRm).
    Petersson, Per-Erik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Bygg och Mekanik.
    Slab test: Freeze/thaw resistance of concrete - Internal deterioration2004In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 37, no 274, p. 754-759Article in journal (Refereed)
  • 19. Maurenbrecher, P
    et al.
    Lindqvist, Jan Erik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    RILEM TC 203-RHM: Repair mortars for historic masonry: Requirements for repointing mortars for historic masonry2012In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 45, no 9, p. 1303-1309Article in journal (Refereed)
    Abstract [en]

    This paper gives a summary of functional and performance requirements for repointing mortars for historic masonry (design, execution and maintenance). Successful performance of repair and conservation of mortar in historic masonry requires more care with design and execution than with modern masonry.

  • 20.
    Mechtcherine, V.
    et al.
    Technische Universität Dresden, Germany.
    Gram, Annika
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Krenzer, K.
    Institut für Angewandte Bauforschung Weimar GGmbH, Germany.
    Schwabe, J-H.
    University of Applied Science Jena, Germany.
    Shyshko, S.
    Technische Universität Dresden, Germany.
    Roussel, N.
    Université Paris Est, France.
    Simulation of fresh concrete flow using Discrete Element Method (DEM): theory and applications2014In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 47, no 4, p. 615-630Article in journal (Refereed)
    Abstract [en]

    This article provides an overview of the development and the contemporary state of research in the field of simulating fresh concrete flow using the Discrete Element Method (DEM). First, this work originating from TC 222-SCF simulation of fresh concrete flow, covers the mathematical methodology, the identification of the model parameters and the link between the rheological properties of fresh concrete and the parameters of DEM-based models. Various examples of the estimation of model parameters and calibration of the model were demonstrated, followed by verifications by comparing the numerical results and the corresponding predictions by analytical formula and laboratory experiments. Furthermore, software used in concrete engineering and existing industrial applications of the developed particle models were described, showing the potential of DEM.

  • 21. Miccoli, L
    et al.
    Oliveira, Daniel V
    Static behaviour of rammed earth: Experimental testing and finite element modelling2014In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873Article in journal (Refereed)
    Abstract [en]

    The paper presents an experimental program aiming at assessing the mechanical performance of rammed earth walls, namely under compression and shear loading. Axial compression and diagonal compression tests were carried out for this purpose, which allowed determining important mechanical parameters, such as compressive strength, Young's modulus, Poisson's ratio, shear strength and shear modulus. Furthermore, it allowed assessing the level of non-linear behaviour of the respective stress-strain relationships as well as the failure modes. The experimental results were then used in the calibration of numerical models (finite element method) for simulating the non-linear behaviour of rammed earth under shear loading. Both macro- and micro modelling approaches were considered for this purpose. The total strain rotating crack model was used to simulate the behaviour of the rammed earth material, while the Mohr-Coulomb failure criterion was used to simulate the behaviour of interfaces between layers. In general, the numerical models achieved good agreement with the experimental results, but uncertainties related to the definition of the input parameters required to perform a sensitivity analysis. The compressive strength, the Poisson's ratio, the tensile strength and the tensile fracture energy revealed to be the most important parameters in the analyses

  • 22.
    Olsson, Anders
    et al.
    Linnaeus University, Sweden.
    Källsner, Bo
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Hållbar Samhällsbyggnad. Linnaeus University, Sweden.
    Shear modulus of structural timber evaluated by means of dynamic excitation and FE analysis2015In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 48, no 4, p. 977-985Article in journal (Refereed)
    Abstract [en]

    In this study the results from dynamic excitation of 105 centre boards of Norway spruce in edgewise bending are evaluated with respect to shear modulus using the FE method. Advantages of the method presented here, in relation to the torsion method given in EN 408 (Timber structures—structural timber and glued laminated timber—determination of some physical and mechanical properties, 2010), are that the testing is very simple to carry out and also that the shear stresses occur in the same way as in a beam subjected to bending. Although no alternative methods for evaluation of the shear modulus were applied in this study, results indicating a robustness of the suggested method are presented. According to calculations the estimated shear modulus varies considerably between different boards. The calculated mean value and standard deviation of the dynamic shear modulus is about 744 and 106 MPa, respectively. No significant correlation between the estimated shear modulus and the measured static modulus of elasticity in bending was found, but a correlation between calculated shear modulus and density was identified (R 2 = 0.24). Conclusions of the results are that dynamic excitation of boards should be considered as an alternative method for determination of shear modulus in EN 408 (Timber structures—structural timber and glued laminated timber—determination of some physical and mechanical properties, 2010), and a relation between the board density and the board shear modulus, rather than a relation between the board MOE and the board shear modulus, should be stated in EN 338 (Structural timber—strength classes, 2009).

  • 23.
    Serrano, Erik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Gustafsson, P.J.
    Fracture mechanics in timber engineering – Strength analyses of components and joints2007In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 40, no 1, p. 87-96Article in journal (Refereed)
  • 24.
    Silva, Nelson
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Tang, Luping
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Application of LA-ICP-MS for meso-scale chloride profiling in concrete2013In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 46, no 8, p. 1369-1381Article in journal (Refereed)
    Abstract [en]

    Chloride represents a major risk for reinforced concrete structures because at a certain concentration, it can promote depassivation of the steel bars and initiate corrosion. Therefore it is important to be able to measure the chloride content in concrete. In this paper the application of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for the study of chlorides in concrete is proposed. This scanning technique enables quick multi-element profiling, directly at the sample without the need for further preparation, within a range of sub-millimetre (meso-scale) resolution and with low limits of detection. Optimization of the operating conditions was performed in pressed concrete powder pellets. Linearity of the calibration was verified and limits of detection below 0.05 wt% of cement were determined. Chlorine, calcium and iron distributions were studied in cement based materials of increasing heterogeneity (paste, mortar and concrete). This technique is furthermore proposed for the study of the chloride induced corrosion process, by following element distributions along the concrete-steel interface at the time of depassivation.

  • 25. Skoglund, Pål
    et al.
    Silfwerbrand, Johan
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Chloride redistribution and reinforcement corrosion in the interfacial region between substrate and repair concrete: a laboratory study2008In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 41, no 6, p. 1001-1014Article in journal (Refereed)
  • 26.
    Sterley, Magdalena
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Serrano, Erik
    SP - Sveriges Tekniska Forskningsinstitut, SP Trä.
    Enquist, Bertil
    Fracture characterisation of green-glued polyurethane adhesive bonds in Mode I2013In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 46, no 3, p. 421-434Article in journal (Refereed)
  • 27. Tlustochowicz, Gabriela
    et al.
    Serrano, Erik
    SP- Sveriges Tekniska Forskningsinstitut, Trätek.
    Steiger, René
    State-of-the-art review on timber connections with glued-in steel rods2011In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 44, no 5, p. 997-1020Article in journal (Refereed)
  • 28. van Hees, R
    et al.
    Lindqvist, Jan Erik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    RILEM TC 203-RHM: Repair mortars for historic masonry.: From problem to intervention: a decision process2012In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 45, no 9, p. 1295–1302-Article in journal (Refereed)
    Abstract [en]

    This article focuses on repair or replacement mortars for historical buildings. Both the decision process and questions arising are dealt with, in order to better define and illustrate technical requirements for mortars to be used for the repair or restoration of monuments and historic buildings (masonry mortars, plasters, renders). The article summarizes a longer document, meant to help professionals in their decisions on the interventions, taking into account aspects, which are ranging from the ethics of restoration to the technical requirements

  • 29. Vessby, Johan
    et al.
    Serrano, Erik
    SP- Sveriges Tekniska Forskningsinstitut, Trätek.
    Enquist, Bertil
    Contact-free measurement and numerical and analytical evaluation of the strain distribution in a wood-FRP lap-joint2010In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 43, no 8, p. 1085-1095Article in journal (Refereed)
  • 30.
    Williams Portal, Natalie
    et al.
    RISE - Research Institutes of Sweden, Built Environment, CBI Swedish Cement and Concrete Research Institute. Chalmers University of Technology, Sweden.
    Nyholm Thrane, Lars
    DTU Technical University of Denmark, Denmark.
    Lundgren, Karin
    Chalmers University of Technology, Sweden.
    Flexural behaviour of textile reinforced concrete composites: experimental and numerical evaluation2017In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 50, no 4, p. 1-14Article in journal (Refereed)
    Abstract [en]

    Textile reinforced concrete (TRC) is an innovative high performance composite material which has revealed many promising attributes in various applications but test methods and reliable numerical models need to be established to reduce uncertainty and the need for extensive experimental studies. The aim of this paper was to evaluate the flexural behaviour of carbon textile reinforced TRC slabs both experimentally and numerically along with the characterization of the material and interaction level properties. The experimental results characterizing the bond behaviour were linked to the experimental behaviour of a rectangular TRC slab in bending through numerical analyses. A 2D macro-scale FE-model of the tested TRC slab was developed based on the related experimental input. Comparison of the numerical results to the experiments revealed that the flexural failure was governed by bond, and reasonable agreement was obtained in terms of crack development, deflections, maximum load, and failure mode. Accordingly, the experiments further indicated that the flexural behaviour of TRC slabs is greatly influenced by the bond quality.

1 - 30 of 30
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