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  • 1. Adolfi, Bengt
    et al.
    Hameury, Stephane
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Jegerfors, K
    Landström, A
    Trälyftet: Ett byggsystem i massivträ för flervåningshus2005Rapport (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    Trälyftet" presenterar ett byggsystem - bestående av industriellt tillverkade volymer med stommar av massivträ - som gör det möjligt att bygga moderna, robusta flervåningshus av prefabricerade volymer i massivträ. Vi får ta del av forskningen bakom byggsystemet, funktionen och erfarenheterna från det första prototyphuset. Även konstruktioner och installationer beskrivs.

  • 2.
    Ahmed, Lamis
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Betongbyggnad.
    Guarin, Alvaro
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Crack propagation under water pressure2018Rapport (Refereegranskat)
    Abstract [en]

    Cracks in concrete structures such as a concrete dam can be exposed to water pressure, for example, uplift pressure. The water pressure can be significant and may result in cracks propagating through the structures and thus it may result in reduced service life. However, the knowledge of water pressure within the cracks is relatively limited and is often neglected or just roughly estimated. The influence of crack opening rate on the uplift pressure distribution in the crack and the pressure variation during opening or sudden crack closure are questions needed to investigate. As an attempt to answer those questions, a pilot study presented here describes the possibilities and limitations of the proposed experimental setup; and technology (penetrability meter and tomography) as an examination method for water pressure in propagation concrete cracks. The test specimens examined here are exclusively cylinders cast of concrete with or without an initial crack.

    The penetrability meter can be used to apply water pressure and to visualize the crack opening, X-Ray computed tomography test, was performed. KTH Civil and Architectural Engineering department has organized the laboratory resources.

    The examples reported in this work show that the technology and equipment have great potential for future work on crack propagation, however, sample design and preparation, as well as testing need further development.

  • 3.
    Ansell, Anders
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Betongbyggnad.
    Ahmed, Lamis
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Betongbyggnad.
    Guarin, Alvaro
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Computed tomography as investigation method for steel fibre reinforced tunnel shotcrete2017Konferensbidrag (Refereegranskat)
  • 4.
    Ansell, Anders
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Betongbyggnad.
    Ahmed, Lamis
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Betongbyggnad.
    Guarin, Alvaro
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Datortomografi som undersökningsmetod för ung och gammal, sprutad och gjuten betong för tunnlar2016Rapport (Övrigt vetenskapligt)
  • 5.
    Ansell, Anders
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Betongbyggnad.
    Nordström, Erik
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Betongbyggnad. Sweco Energuide, Hydro Power & Dams, Stockholm, Sweden.
    Guarin, Alvaro
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Laboratory investigation of steel fibre reinforced sprayed concrete using a computed tomography method2018Ingår i: Eight International Symposium on SPRAYED CONCRETE - Modern Use of Wet Mix Sprayed Concrete for Underground Support, 2018, s. 24-38Konferensbidrag (Refereegranskat)
    Abstract [en]

    A laboratory method for investigation of cored samples of steel fibre reinforced sprayed concrete (shotcrete) is described. A pilot study on computed tomography (CT) has been conducted, with focus on how the technique can be used for non-destructive testing where the cores remain intact after scanning and evaluation. The CT method require advanced integrated equipment for X-ray scanning and image detection, together with a computerized visualization system that can reproduce a threedimensional virtual, transparent model of the studied object. The method is well suited to describe orientation and distribution of steel fibres within the concrete. Interfaces between rock-concrete and concrete-concrete, between layers of differentsequences ofspraying, can also be identified. The results from the CT investigations can be presented as qualitative data that in 3D shows locations of steel fibres, aggregates, etc., and also as quantitative data showing relative distributions of cement paste, aggregates, steel fibres and voids, which is here demonstrated by a selection of examples. The method is well suited for practical analysis of sprayed concrete in situ specimens and it is recommended that it is established as a standard method for special inspections and performance evaluation of rock support in tunnels and subspace structures.

  • 6. Arm, Maria
    et al.
    Wik, Ola
    Engelsen, Christian J.
    Erlandsson, Martin
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Hjelmar, Ole
    Wahlström, Margareta
    How Does the European Recovery Target for Construction & Demolition Waste Affect Resource Management?2017Ingår i: Waste and Biomass Valorization, ISSN 1877-2641, E-ISSN 1877-265X, Vol. 8, nr 5, s. 1491-1504Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The revised EU Waste Framework Directive (WFD) includes a 70 % target for recovery of construction and demolition (C&D) waste. In order to study the potential change in the resource management of the main C&D waste fractions, as a consequence of fulfilling the WFD target, a Nordic project (ENCORT-CDW) has been performed. Waste fractions studied included asphalt, concrete, bricks, track ballast, gypsum-based construction materials and wood. Recovery scenarios were identified and estimations were made regarding expected savings of primary materials, impact on transport, and pollution and emissions. For wood waste, the main differences between re-use, material recycling and energy recovery were evaluated in a carbon footprint screening based on life cycle assessment methodology. The study concluded that the EU recovery target does not ensure a resource efficient and environmentally sustainable waste recovery in its present form since: It is very sensitive to how the legal definitions of waste and recovery are interpreted in the Member States. This means that certain construction material cycles might not count in the implementation reports while other, less efficient and environmentally safe, recovery processes of the same material will count. It is weight-based and consequently favours large and heavy waste streams. The result is that smaller flows with equal or larger resource efficiency and environmental benefit will be insignificant for reaching the target. It does not distinguish between the various recovery processes, meaning that resource efficient and environmentally safe recovery cannot be given priority. Improved knowledge on C&D waste generation and handling, as well as on content and emissions of dangerous substances, is required to achieve a sustainable recovery.

  • 7.
    Babic, Nino
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Flyttbara byggnader för bostadsändamål: Kompatibla med de nya tidsbegränsade byggloven2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Bostadsbyggandet i Sverige står inför kommande utmaningar. Bostadsbristen ökar och många av landets kommuner anser att de redan nu har en stor bostadsbrist. En orsak som ofta pekas ut är tiden det tar för kommunen att arbeta fram en detaljplan. Samtidigt skärps kraven avseende energiförbrukning för byggnader som byggs efter år 2020. Som en motåtgärd har riksdagen nyligen röstat igenom en lag som utökar möjligheterna att utnyttja de tidsbegränsade byggloven för att bygga tillfälliga bostäder. Tidsbegränsade bygglov kan då utnyttjas för att tillfälligt tillgodose behovet samtidigt som kommunen kan arbeta fram en detaljplan dit byggnaderna sedan flyttas. I detta examensarbete undersöks det hur detta skulle kunna implementera, och samtidigt bibehålla prestandan som byggnaderna är tänkte att ha.

     

    Syftet med detta arbete är att undersöka om KL-trä kan användas på ett tidigare outnyttjat sätt, genom att bygga flyttbara moduler som är kompatibla med tidsbegränsade bygglov för att på ett snabbt sätt kunna tillgodose det stora bostadsbehovet. Den stora frågan som detta examensarbete försöker att besvara är ”Hur kan man bygga flyttbara bostadshus med KL-trä som når den nya miljömålen som kommer år 2020?”. Målet är därför att göra en kartläggning och presentera lösningar på de frågor och tveksamheter som kan finnas kring flyttbara byggnader med KL-trästomme, både innan och efter flytt.

    Trä har länge använts som ett byggmaterial i norra Europa. I Sverige förstördes många städer under 1700- och 1800-talet av bränder. För att förhindra brand och brandspridning mellan byggnader infördes år 1874 ett förbud mot att bygga fler än två våningar i trä, ett förbud som varade i mer än 100 år. Detta ledde till att andra material utvecklades och tog stora marknadsandelar i flerbostadshusmarknaden. År 1994 tilläts det än en gång att bygga högt i trä i samband med att Sverige gick med i EU. Att använda trä som stommaterial har många fördelar, men innebär också specifika områden som är viktiga att ägna uppmärksamhet. KL-trä är ett relativt nytt stommaterial i Sverige och utvecklingen har lett till praktiska lösningar på de problem som är förknippade med trästommar. 

    Genom att utnyttja fördelarna som KL-trä innebär kan flerbostadshus byggas med volymelement som lever upp till dem krav som ställs på flerbostadshus enligt Boverkets byggregler, BBR. Fördelarna är bland annat låg egenvikt, låg värmekonduktivitet och en trevlig arbetsmiljö. Arbetets slutsatser är bland annat:

    • För att nå ett gott resultat i hela processen är det viktigt att planeringen håller hög kvalitet.
    • Stor vikt bör läggas på utformning av brandskydd och akustisk prestanda som lever upp till kraven på platsen för det tidsbegränsade bygglovet och på återuppställningsplatsen.*
    • I projekteringsskedet är det viktigt att se till att de valda tekniska lösningarna är lätta att installera och plocka isär. 
  • 8.
    Bekele, Abiy
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Application of Automated Non-contact Resonance Testing for Low Temperature Behavior of Asphalt Concrete2019Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Impact resonance testing is a well-documented non-destructive testing method and its applications on asphalt concrete have also been implemented successfully. The test is carried out manually by inducing an impact in order to excite the test specimen and taking measurements of the vibrational response. In an effort to improve the manual procedure of impact resonance testing, an automated non-contact methodology is developed and its applicability with regards to low temperature behaviors of asphalt concrete is investigated. Results from this work show that repeatable fundamental resonance frequency measurements can be performed on a disc shaped specimen in an automated manner without the need to open the thermal chamber. The measurements obtained from the new method have been verified by taking similar resonance frequency measurements using an instrumented impact hammer. It has also been shown in this work that the proposed method is suitable to investigate the lone effects of cyclic thermal conditioning on asphalt concrete without any other possible biasing effects associated with contact in the conventional testing. A hysteretic behavior of stiffness modulus is obtained on three different asphalt concrete specimens subjected to repeated low temperature cyclic conditioning. Reduced modulus values at each temperature are obtained in all the tested specimens after a low temperature stepwise conditioning at temperatures from 0oC to -40 oC. This observed behavior shows that the dynamic modulus of the tested specimens is affected by low temperature conditioning. The norm of the complex modulus decreases and the phase angle or damping ratio increases after low temperature conditioning. Hence, valuable and practical low temperature characteristics of different asphalt concrete mixtures can possibly be obtained by using the proposed methodology.

  • 9.
    Bekele, Abiy
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Automated Non-contact Resonance Excitation Method for Low Temperature Behavior of Asphalt ConcreteManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    This paper studies the applicability of an automated non-destructivetesting method to monitor the stiffness of asphalt concrete at lowtemperatures. A loudspeaker is used as a source of non-contact excitation ofthe axially symmetric fundamental resonance frequencies of a disc-shapedasphalt concrete specimen positioned inside an environmental chamber. Measuredresonance frequencies are used to calculate the dynamic moduli of the specimenat different temperatures. The repeatability of the method as well as theeffect of loudspeaker height above the sample are studied. Results show thatthe main advantage of the non-contact excitation method, compared to manuallyapplied impact hammer excitation, is that repeatable automated measurements canbe performed while the specimen is placed inside an environmental temperaturechamber. This methodology enables to study the effect of only low temperatureconditioning on the dynamic modulus of asphalt concrete without interferencefrom mechanical loading.

  • 10.
    Bekele, Abiy
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Effect of Cyclic low temperature conditioning on Stiffness Modulus of Asphalt Concrete based on Non-contact Resonance testing methodManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The stiffness modulus behaviors of three different asphalt concrete specimens that are subjected to cyclic cooling and heating are monitored. In an attempt to identify the sole effect of temperature cycles and to avoid any other biasing effects such as thermal contamination that can possibly corrupt measurements, resonance frequency measurements of the specimens are taken using an automated non-contact resonance method. The resonance frequency measurements are based on the fundamental axially symmetric mode of vibration. A hysteretic effect is observed on the measured resonance frequencies of the specimens with an application of cyclic cooling and heating. Lower stiffness moduli are obtained during the heating phase of a complete cooling and heating cycle. The stiffness moduli are calculated from measured resonance frequencies of the specimens in order to show their relative reductions due to the hysteretic effect. This finding is particularly important since it enables us to observe and understand the effect of the thermal history of asphalt concrete with regards to the reversibility behavior of its stiffness modulus. The damping of the specimens is also calculated from the measured resonance frequencies at the temperatures within the applied cyclic cooling and heating. Their observed behavior is also discussed with respect to a presence of potential micro damage.

  • 11.
    Bekele, Abiy
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Birgisson, Björn
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Vägtekniks laboratorium.
    Rydén, Nils
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Gudmarsson, Anders
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Slow dynamic diagnosis of asphalt concrete specimen to determine level of damage caused by static low temperature conditioning2017Ingår i: 43rd Annual Review of Progress in Quantitative Nondestructive Evaluation, American Institute of Physics (AIP), 2017, Vol. 1806, artikel-id 080012Konferensbidrag (Refereegranskat)
    Abstract [en]

    The phenomenon of slow dynamics has been observed in a variety of materials which are considered as relatively homogeneous that exhibit nonlinearity due to the presence of defects or cracks within them. Experimental realizations in previous work suggest that slow dynamics can be in response to acoustic drives with relatively larger amplitude as well as rapid change of temperature. Slow dynamics as a nonlinear elastic response of damaged materials is manifested as a sharp drop and then recovery of resonance frequency linearly with logarithmic time. In this work, slow dynamics recovery is intended to be used as a means of identifying and evaluating thermal damage on an asphalt concrete specimen. The experimental protocol for measuring slow dynamics is based on the technique of nonlinear resonance spectroscopy and is set up with non-contact excitation using a loud speaker and the data acquisition tool box of Matlab. Sweeps of frequency with low amplitude are applied in order to probe the specimen at its linear viscoelastic state. The drop and then recovery in fundamental axially symmetric resonance frequency is observed after the specimen is exposed to sudden temperature change. The investigation of the viscoelastic contribution to the change in resonance frequency and slow dynamics can help identify micro-damage in asphalt concrete samples.

  • 12. Bressi, S.
    et al.
    Dumont, A. G.
    Partl, Manfred N.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial. Carleton University, Ottawa, Canada; Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland.
    A new laboratory methodology for optimization of mixture design of asphalt concrete containing reclaimed asphalt pavement material2016Ingår i: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 49, nr 12, s. 4975-4990Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The reduction of virgin bitumen added to asphalt mixtures containing Reclaimed Asphalt Pavement (RAP) is based on the typical assumption that all the aged binder function in the same way as the virgin binder. However, recent studies conducted by the authors for a specific case show that a blend or mobilization of RAP binder are negligible. The aged bitumen becomes softer acting as glue facilitating cluster formation between small-size RAP particles. The reduction of small-size particles causes changes in the target grading curve and in the voids-fill, affecting the compactability of RAP mixtures. Therefore the target grading curve of RAP mixtures needs to be readjusted, using different proportions of virgin aggregates and taking into account the cluster phenomenon. The objective of this paper is to develop a new mix design approach for RAP mixtures, taking into account the cluster phenomenon and the contribution of the aged bitumen in the compactability. The virgin aggregates, filler and RAP are investigated and individually included in the calculation. 3D images of the virgin aggregates allowed the determination of new surface area factors; the concept of critical filler concentration led to the definition of the minimum bitumen quantity required to maintain the mastic in a diluted state and fill the voids. A RAP clustering model was introduced to predict the agglomeration of small-size RAP particles. The readjustment of the target grading curve was analytically calculated, allowing the correct estimation of the amount of virgin bitumen to be added to asphalt mixtures. Finally, a first verification of the entire process was carried out performing laboratory tests. These promising results enable the challenge of a new mix design optimization for HMA with high RAP content to be addressed.

  • 13. Bressi, Sara
    et al.
    Dumont, A. G.
    Partl, Manfred
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial. Carleton Univ, Ottawa, Canada.
    An advanced methodology for the mix design optimization of hot mix asphalt2016Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 98, s. 174-185Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The bitumen quantity to add to asphalt mixtures depends on the surfaces of aggregates and filler to be coated. The formulas currently available in the literature have limitations such as considering all the fillers with the same specific surface or the aggregates with spherical or cubical shapes. This paper aims to define an analytical approach for the determination of the optimal dosage of bitumen in HMA proposing new methodologies to go a step further in the resolution of the above mentioned approximations. Indeed, new surface area factors were calculated to determine the aggregates surface considering their real shapes and volumes. Afterwards, the authors proposed a detailed characterization of two types of fillers and the critical filler concentration, introduced by Faheem and Bahia, was used to calculate the minimum amount of bitumen for maintaining the mastic in a diluted state and filling the voids in the mixtures. Finally, a verification of the formula developed was carried out with specific laboratory tests. These results allow the challenge of revising the method of calculating the specific surface of the aggregates and filler to be addressed with the final goal to include them in a new mix design optimization for HMA. 

  • 14.
    Bryne, Lars Elof
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Lausamaa, J.
    Ernstsson, M.
    Englund, Finn
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Söderström, Ove
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    UV-laser irradiated wood: Some aspects on micromorphology, wettability, surface composition and liquid permeability2008Ingår i: Proceedings of the 4th meeting of the Nordic-Baltic network in wood material science and engineering (WSE), 2008, s. 75-82Konferensbidrag (Refereegranskat)
    Abstract [en]

    Many wood products used as building or construction materials involve a combination of the wood material with polymers, such as adhesives, coatings, preservatives and binders in composites. Combinations of wood and polymers in outdoor exposure, however, in general have poor long-term durability. A major cause of the unsatisfactory durability can be related to the high hygroscopicity of wood and the great difference in hygro-thermal properties between the components, resulting in wood-polymer de-bonding. In addition, mechanical processing (e.g. sawing, sanding and planning) of wood in general forms a weak boundary layer of loose and crushed wood cells in the surface which also may interfere with the wood-polymer bonding. The main objective of this work was to study ultra violet (EV), or excimer, laser irradiation on wood as a means to remove, by ablation, the outer deformed layer from a wood substrate. Effects of the UV-laser treatment on wetting and liquid permeability characteristics were studied by Wilhelmy plate experiments, and effects on the wood surface chemistry were studied by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The micromorphology of wood was studied by low vacuum-scanning electron microscopy (LV-SEM). The pre-treatment of wood substrates by UV-laser ablation resulted in a notable changes in surface micromorphology, liquid permeability, wettability and surface chemistry characteristics.

  • 15.
    Bryne, Lars-Elof
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Aspects on wettability and surface composition of modified wood2008Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Wood is often combined with other materials such as thermoplastics, adhesives and coatings. In general, combinations of wood and polymers especially in outdoor exposure have poor long-term durability. This behaviour can be related to an insufficient wood-polymer adhesion due to the low intrinsic compatibility between the wood substance and the polymers used. Another source for woodpolymer de-bonding is the high hygroscopicity of wood and great difference in hygro-thermal properties between the components.

    The basic conceptual idea related to this work is to reduce the hygrosensitivity of wood by applying different wood modification methods, in particular, acetylation, furfurylation and heat treatment. The effects of such chemical modifications of wood, also accompanied with ageing effects, on its adhesion properties with commonly used synthetic polymers are, however, not well understood. In this context, the over-all purpose of this thesis is to achieve a better understanding of wood-polymer adhesion and interfacial forces which also may guide us to tailor the interaction between modified wood and e.g. thermoplastics and adhesives. The main focus of this thesis is therefore to apply contact angle analysis based on the Chang-Qin-Chen (CQC) Lewis acid-base model in order to estimate the work of adhesion (Wa) between the wood, modified wood and certain polymers. Contact angle measurements on wood samples were performed based on the Wilhelm plate principle. Related to this, an effort was also made to characterize the studied modified wood surfaces according to morphology and chemical composition. The methods that have been used are low vacuum scanning electron microscopy (LV-SEM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS).

    Results show that so-called interaction parameters can be successfully estimated for prediction of Wa between wood and polymers using the applied CQC model. Furthermore, such wetting analysis was successfully related to spectroscopic findings of the chemical composition of the wood samples surface. Ageing effects, i.e. the time after preparation of the wood surface, play a central role for the surface characteristics. In most cases, ageing resulted in a significant decrease of Wa between wood and water and a moderate decrease between wood and thermoplastics. The surface characteristics of acetylated wood were, however, more stable over time compared to unmodified, furfurylated and heat treated wood. The predicted Wa with the adhesives for heat treated and acetylated wood was increased due to ageing. Future work is planned to involve studies in order to relate such predicted adhesion properties with the actual performance of various wood-polymer systems.

  • 16.
    Bryne, Lars-Elof
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Lausmaa, Jukka
    SP Technical Research Institute of Sweden, Chemistry and Materials Technology, Borås, Sweden.
    Ernstsson, Marie
    Institute for Surface Chemistry, Stockholm, Sweden.
    Englund, Finn
    SP Trätek, Technical Research Institute of Sweden, Wood Technology, Borås, Sweden.
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Ageing of modified wood: Part 2: Determination of surface composition of acetylated, furfurylated, and thermally modified wood by XPS and ToF-SIMS2010Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 64, nr 3, s. 305-313Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The main objective of this work was to study the chemical composition of surfaces and ageing effects on acetylated pine (Pinus sylvestris), heat treated spruce (Picea abies), and furfurylated radiata pine (Pinus radiata) in comparison to unmodified wood. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were the instruments of choice. Observation with a low-vacuum scanning electron microscope (LV-SEM) complemented the study. The spectroscopic information was also linked to a parallel wettability study on matched wood samples by the Wilhelmy method. The results show that XPS and ToF-SIMS are two powerful tools that in combination give complementary information, both quantitative and qualitative, and are well suited for observation of the ageing process of different wood surfaces. The hydrophobization process as a result of migration of extractives during ageing was well quantified by the XPS measurements and the results correlated well with wetting results. Several specific hydrophobic substances could be identified by ToF-SIMS measurements.

  • 17.
    Bryne, Lars-Elof
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Ageing of modified wood: Part 1: Wetting properties of acetylated, furfurylated, and thermally modified2010Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 64, nr 3, s. 295-304Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The main objective of this work was to apply contact angle analysis to predict work of adhesion (W-a) between some modified wood materials and certain thermoplastics and adhesives. Wetting properties, i.e., contact angles, were measured by the Wilhelmy method on both freshly prepared and aged veneer samples of unmodified and acetylated Scots pine, furfurylated radiata pine, and heat treated Norway spruce. The sessile drop method was used to measure contact angles on a phenol resorcinol formaldehyde, an emulsion polymer isocyanate, and a one-component polyurethane adhesive. Contact angle data were also collected from the literature on polyethylene, polyvinyl chloride, polymethyl methacrylate, polystyrene, and Nylon 6. Contact angle analysis based on the Chang-Qin-Chen model was then applied to determine so-called acid-base interaction parameters and W-a between the wood samples and the selected thermoplastics and adhesives. Results show that the ageing process led to an increased hydrophobic character of unmodified, heat treated, and furfurylated wood samples. The freshly prepared acetylated wood samples had a pronounced hydrophobic character which remained approximately constant after ageing. The predicted W-a between the wood and the adhesives was considerably higher than that between the wood and the thermoplastics. Furthermore, the predicted W-a between the acetylated wood and both the thermoplastics and water was approximately unchanged when comparing the fresh and aged samples. In contrast, the ageing of all other wood samples resulted in a dramatic decrease of the wood-water W-a and a moderate decrease of the wood-thermoplastics W-a. The wood-adhesives W-a, however, was unchanged for the unmodified and furfurylated wood when comparing the fresh and aged samples and even increased for heat treated and acetylated wood samples.

  • 18. Bueno, M.
    et al.
    Hugener, M.
    Partl, Manfred
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Fracture toughness evaluation of bituminous binders at low temperatures2015Ingår i: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 48, nr 9, s. 3049-3058Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    When asphalt roads turn brittle at low temperatures, they are no longer able to relax completely from traffic induced stresses and may also suffer damage through crack initiation and propagation. In order to avoid early structural damages, the bituminous binders must be selected very carefully. However, conventional test methods for assessing performance of bituminous binders at low temperatures are often unsatisfactory reliable, in particular in case of polymer modified bituminous binders. In this study, an alternative experimental method based on fracture mechanical principles was performed on pre-notched specimens in the brittle state inside a cooling media. This fracture toughness test was evaluated in terms of its suitability for distinguishing different types of polymer modified and unmodified bituminous binders. In addition, the feasibility to evaluate different ageing states was also analysed by testing samples after artificial short-term and long-term ageing procedures. The repeatability obtained from the experimental results showed that the fracture toughness test is a suitable candidate for being introduced in a standardization framework.

  • 19. Canestrari, F.
    et al.
    Ferrotti, G.
    Lu, X.
    Millien, A.
    Partl, Manfred
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial. Empa, Swiss Federal Laboratories for Materials Science and Technology.
    Petit, C.
    Phelipot-Mardelé, A.
    Piber, H.
    Raab, C.
    Mechanical testing of interlayer bonding in asphalt pavements2013Ingår i: Advances in Interlaboratory Testing and Evaluation of Bituminous Materials, Springer Netherlands, 2013, s. 303-360Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Steadily increasing requirements on pavement performance properties, in terms of bearing capacity and durability, as well as new innovative developments regarding pavement materials and construction, are observed worldwide. In this context interlayer bonding at the interfaces of multi-layered bituminous systems is recognized as a key issue for the evaluation of the effects, in terms of stress-strain distribution, produced by traffic loads in road pavements. For this reason a correct assessment of interlayer bonding is of primary importance, and research efforts should be addressed in order to improve the lack of correlation and/or harmonization among test methods. Following this principle RILEM TG 4 organized an interlaboratory test in order to compare the different test procedures to assess the interlayer bonding properties of asphalt pavement. The results of the experimental research are presented with a preliminary overview of basic elements, test methods and experimental investigations on interlayer bonding. Then the RILEM TG 4 experimental activities, based on the construction of three real- scale pavement sections, are presented in detail. Each pavement section was composed of two layers, and three different interface conditions were chosen. The first pavement was laid without interface treatment and the others with two different types of emulsion. Fourteen laboratories from 11 countries participated in this study and carried out shear or torque tests on 1,400 cores. The maximum shear or torque load and the corresponding displacement were measured, and the shear or torque strength was calculated as a function of the following parameters: diameter, test temperature, test speed, stress applied normal to the interface and age of the specimen. The results of this study are presented in terms of precision and correlations regarding the parameters which results in useful information on asphalt pavement interlayer bond tests.

  • 20.
    Celma Cervera, Carlos
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Jelagin, Denis
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Partl, Manfred N.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial. bEMPA Swiss Federal Laboratories for Materials Testing and Research, Switzerland.
    Larsson, Per-Lennart
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Contact-induced deformation and damage of rocks used in pavement materials2017Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 133, s. 255-265Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Performance of stone-based construction materials, such as asphalt and unbound aggregate mixtures is defined to a great extent by the mechanics of the stone-to-stone interactions. Accordingly, the Discrete Element Method (DEM) is gaining popularity as a modelling tool to investigate the mechanical behavior of these materials. Contact and failure laws defining particles force-displacement relationships and the propensity of particles to break are crucial inputs for the DEM simulations. The present study aims at providing an experimental contact mechanics basis for the development of physically based stone-to-stone interaction laws. The attention is focused on investigating stone's force-displacement relationship and damage characteristics at pure normal loading for two stone materials used by the road industry. Experiments are performed at spherical contact profiles for cyclic and monotonically increasing loads. The emphasis lies on the evolution of contact compliance and accumulation of contact induced damage. The effect of surface roughness on the materials response is examined through comparative experiments performed on the specimens with different roughness values. Optical and environmental scanning electron microscopy (ESEM) observations of the contact induced damage at the material surface are presented and discussed in the context of contact mechanics. The implications of the reported experimental findings on the development of mechanics based contact and failure laws for the DEM modelling of stone-based construction materials are discussed.

  • 21. Chailleux, E.
    et al.
    Partl, M. N.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    General summary and outlook2013Ingår i: RILEM State-of-the-Art Reports, Springer, 2013, s. 429-438Konferensbidrag (Refereegranskat)
    Abstract [en]

    Final considerations based on the experience and feedback of this RILEM technical committee TC 206-ATB on “Advanced Testing and Characterization of Bituminous Materials” are given. Some open questions within the general methodology as introduced in Chap. 1 and used as guideline for RILEM activities are listed. Future prospects and direction of activities of joint voluntary research efforts within the frame of such asphalt-related committees are also discussed. It is suggested that these future efforts will most certainly have to focus even more on sustainability and environmental aspects but without neglecting general materials and systems quality aspects during production and construction as well as safety and performance during use. Future activities will also have to dealwith multifunctionality aspects of pavements and multi-scaling approaches as a basis for better understanding and tailoring of pavements and pavement materials.

  • 22.
    Chen, Feng
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Jelagin, Denis
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Partl, Manfred
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial. EMPA–Swiss Federal Laboratories for Materials Science and Technology, Duebendorf, Switzerland.
    Experimental and numerical analysis of asphalt flow in a slump test2019Ingår i: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 20, s. S446-S461Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mechanical behaviour of uncompacted asphalt mixtures is still not well understood,threatening directly to the pavement practices such as control of mixture’s workability andsegregation. This situation may become even worse due to the gradually increasing complexityand advances in paving materials and technologies. This study adopts a slump flow testbased on concrete technology and a Discrete Element (DE)-based numerical tool to investigatethe mechanical behaviour of uncompacted asphalt mixture from a microstructural point ofview, particularly focusing on the bituminous binder effects. The combined experimental andnumerical analysis indicates that bitumen distinctly influences the contact interactions withinthe mixture and thus its macroscopic flow, which can be physically interpreted as a combinedeffect of lubricated friction and bonding force. Additional case studies demonstrate that the DEmodel is capable of simulating the flow response of asphalt mixtures under changed particlecontact conditions and driven force.

  • 23. Clemons, Craig M.
    et al.
    Rowell, Roger M.
    Plackett, David
    Segerholm, Kristoffer
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Chapter 13: Wood/nonwood thermoplastic composites2012Ingår i: Handbook of wood chemistry and wood composites, second edition / [ed] Rowell Roger M., Boca Racon, FL: CRC Press, 2012, 2, s. 473-508Kapitel i bok, del av antologi (Refereegranskat)
  • 24. Cooper, Paul A.
    et al.
    Ung, Y. T.
    Edlund, M.-L.
    Jermer, J.
    Söderström, Ove
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Inorganic wood preservative levels in soil near a noise barrier treated with different preservatives after 8 years in service in Sweden2005Ingår i: 36th Annual Meeting of the International Research Group on Wood Protection, 2005Konferensbidrag (Refereegranskat)
  • 25.
    Dahlström, Carl
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsteknik. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Giesen, Emma
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsteknik. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Mould resistance design for external wood frame wall systems: Simulation and evaluation of wall structures under varying conditions of exposure using the MRD model2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Moisture induced damages to building envelopes can result in microbial growth possibly affecting the health and wellbeing of occupants. Recent failing structures and damaged buildings indicate a lack of tools to estimate risk of mould growth and moisture damage. In this work a so-called mould resistance design (MRD) model has been applied for mapping the risk for mould growth on a number of wood-containing wall structures. The MRD model introduces an engineering approach to moisture safety design in a similar way as for structural design, where load and resistance is compared. The MRD model introduces and quantifies the concepts of climatic exposure and material resistance and compares them through an MRD index. This MRD index incorporates a limit state, which gives the critical dose of exposure for a given resistance to initiate onset of mould growth.

     

    Three conceptual wall structures were evaluated and analyzed in terms of MRD index: two wall systems with an air gap and one wall system without. A parametric study investigating the effect of parameter variation on MRD index was conducted. Evaluated parameters were: climate (geographic location), orientation, air changes per hour in the air gap, driving rain penetrating the facade layer, exterior plaster properties and wood type. The simulations were performed using the hygrothermal calculation software WUFI. The results indicate that the wall systems with a ventilated air gap performs better in terms of MRD index i.e. suggests a lower risk of initiation of mould growth than the wall system without air gap. The results of orientation variation show that wall systems perform differently dependent on layering structure. The inherent water sorption properties of the exterior plaster are shown to have a large effect on the results. In addition, uncertainties were found on how to accurately include hydrophobicity as a parameter in the model. The report concludes that geographical location and its specific climate is the most important parameter to consider when designing for moisture safety. The MRD model is recommended to be used in combination with traditional moisture safety evaluation.

  • 26. Das, Prabir
    et al.
    Birgisson, Bjorn
    Jelagin, Denis
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Importance of Thermal Contraction Coefficient in Low Temperature Cracking of Asphalt Concrete2016Ingår i: Proceedings of the Fifty-Ninth Annual Conference of the Canadian Technical Asphalt Association (CTAA): Winnipeg, Manitoba / [ed] Canadian Technical Asphalt Association, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    A major distress mode in asphalt pavements is low temperature cracking, which results from the contraction and expansion of the asphalt pavement under extreme temperature changes. The potential for thermal cracking involves interplay between the environment, the road structure, and importantly the properties of the asphalt mixture. In the present study, the low temperature cracking performance of asphalt mixture has been investigated numerically and experimentally. A low temperature cracking model has been utilized, which was developed by integrating fracture energy threshold into an asphalt concrete thermal fracture model considering non-linear thermal contraction coefficients. Based on the asphalt concrete mixture viscoelastic properties, this enhanced model can predict thermally-induced stresses and fracture temperatures. It was observed that the thermal contraction coefficient in asphalt concrete is non-linear in the temperature range of interest for low temperature cracking. The implications of having non-linear thermal contraction coefficient were investigated numerically. From the analysis, it was found that this enhanced model can be utilized to evaluate the low temperature cracking performance of asphalt mixtures and rank them accordingly. Interestingly, non-linear thermal contraction coefficient gave much better prediction than the linear approach.

  • 27.
    de Frias Lopez, Ricardo
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Silfwerbrand, Johan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Betongbyggnad.
    Jelagin, Denis
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Birgisson, Björn
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Vägtekniks laboratorium. School of Engineering and Applied Science, Aston University, Birmingham, UK.
    Force transmission and soil fabric of binary granular mixtures2016Ingår i: Geotechnique, ISSN 0016-8505, E-ISSN 1751-7656, Vol. 66, nr 7, s. 578-583Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of fines content on force transmission and fabric development of gap-graded mixtures under triaxial compression has been studied using the discrete-element method. Results were used to define load-bearing soil fabrics where the relative contributions of coarse and fine components are explicitly quantified in terms of force transmission. Comparison with previous findings suggests that lower particle size ratios result in higher interaction between components. A potential for instability was detected for underfilled fabrics in agreement with recent findings. It was also found that the threshold fines content provides an accurate macroscopic estimation of the transition between underfilled and overfilled fabrics.

  • 28.
    Englund, F.
    et al.
    Technical Research Institute of Sweden.
    Bryne, Lars Elof
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Ernstsson, M.
    Institute for Surface Chemistry, Stockholm, Sweden.
    Lausmaa, J.
    SP Technical Research Institute of Sweden.
    Wålinder, Magnus E. P.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Spectroscopic studies of surface chemical composition and wettability of modified wood2009Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 4, nr 1-2, s. 80-85Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recent advances in spectroscopic methods used in the surface science field may provide new valuable information about the surface chemical composition of engineering materials. Such methods, combined with wettability analyses, have been applied in the development of well-designed adhesives and coating systems for newly developed and commercially available modified wood materials. The main objective of this paper is to demonstrate and present some aspects on the application of two different state-of-the-art spectroscopic methods for surface chemical composition studies of a complex material such as modified wood. The methods are X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS), the former generating more quantitative data and the latter more qualitative data. The spectroscopic data are also combined with wettability data obtained from contact angle measurements using the Wilhelmy method. Modified wood samples were prepared from pilot plant or commercially produced acetylated, furfurylated and thermally modified wood. Effects of wood surface ageing, i.e. the time after machining, on the surface chemical composition and wettability were also studied. Results clearly indicate a hydrophobization process due to ageing of the unmodified and certain modified wood, probably mainly related to a migration and reformation of extractives in the surface. The surface composition and wettability of acetylated wood was not appreciably affected by the ageing process. Such findings could be quantified by the XPS measurements, which is further discussed and related to the different wood modification routes. ToF- SIMS is a powerful tool and complementary to XPS for identification of, for example, specific hydrophobic substances in the wood surfaces. In addition, this method provides ion images, mapping the lateral distribution of selected secondary ions signals within an analysed wood surface area.

  • 29.
    Englund, F.
    et al.
    Technical Research Institute of Sweden.
    Bryne, Lars-Elof
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Ernstsson, Marie
    Institute for Surface Chemistry, Stockholm, Sweden.
    Lausmaa, J
    SP Technical Research Institute of Sweden.
    Wålinder, M. E. P.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Some Aspects on the Determination of Surface Chemical Composition and Wettability of Modified Wood2009Ingår i: Proceedings of the Fourth European Conference on Wood Modification / [ed] F. Englund, C.A.S. Hill, H. Militz and B.K. Segerholm, Stockholm: SP Technical Research Institute of Sweden , 2009, s. 553-560Konferensbidrag (Refereegranskat)
  • 30.
    Englund, Finn
    et al.
    SP Technical Research Institute of Sweden, Wood Technology.
    Hill, Callum A.S.Militz, HolgerSegerholm, B. KristofferKTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Proceedings of the Fourth European Conference on Wood Modifications2009Proceedings (redaktörskap) (Refereegranskat)
  • 31.
    Eriksson, Maria
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Studie av impregnerbarhet hos trä2010Självständigt arbete på grundnivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 32.
    Fadil, Hassan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Jelagin, Denis
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Larsson, Per-Lennart
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Hållfasthetslära (Avd.).
    Partl, Manfred
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Measurement of the viscoelastic properties of asphalt mortar and its components with indentation tests2019Ingår i: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Reliable determination of material properties is a key component for modelling and performance prediction of asphalt pavements. This paper deals with the potential use of instrumented indentation tests for viscoelastic characterisation of asphalt mortar as a new alternative to existing techniques. The main focus lies on the potential of indentation tests for multi-scale measurement of the shear relaxation modulus. A three-dimensional finite element model of a rigid spherical indenter penetrating an asphalt mortar sample is developed and used to model indentation tests performed at different material scales. The asphalt mortar is modelled as an idealised fine aggregate composite with elastic spheres, suspended within a viscoelastic bitumen mastic matrix. Based on the obtained numerical results the scale-dependency of the shear relaxation modulus measured with the indentation test is investigated. It is shown that the measurement scale is effectively controlled by the size of the indenter-specimen contact area, while the effect of indentation depth is minimal. The minimum contact area size required for obtaining representative properties, measured at the mortar scale, is determined. The viscoelastic parameters obtained from the indentation model are compared to those obtained using a representative volume element (RVE) for the asphalt mortar. In this way, the paper provides a new impulse for linking the mortar and asphalt scales in the multiscale modelling of asphalt mixtures. Feasibility of the proposed testing technique is further evaluated experimentally. Viscoelastic indentation tests are performed on asphalt mastics and mortar at two different sizes of contact areas. Experimental results indicate that indentation tests allow reliable characterisation of mortars relaxation modulus on both macro-scale as well as on individual component level.

  • 33.
    Falk, Andreas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Cross-laminated timber: Driving forces and innovation2013Ingår i: Structures and Architecture: Concepts, Applications and Challenges - Proceedings of the 2nd International Conference on Structures and Architecture, ICSA 2013, CRC Press, 2013, s. 511-518Konferensbidrag (Refereegranskat)
    Abstract [en]

    The first modern applications of massive timber plate elements were seen in bridge decks in Canada and the US in the 1970's. Two decades later the concept was taken as point of departure for extensive research on primarily residential building construction and bridge decks in Central Europe in the early 1990's. Today the range of applications has been widened to include an increasing share of applications in non-residential buildings as well as in geometrically far more complex structures. Thereby the requirements on joint properties, stability and detailing etcetera - i.e. the problem issues - have changed, increasing the demands on innovation and solutions both in research and practice. Thus, issues to research and innovate developed applications and multi-objective approaches have succeeded first basic research efforts. This paper describes this development and defines current needs and proposes topics for further studies for the next generation of structural systems based on cross-laminated timber, CLT.

  • 34.
    Falk, Andreas
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Dietsch, PhilippSchmid, Joachim
    Proceedings of the Joint Conference of COST Actions FP1402 & FP1404 Cross Laminated Timber: A competitive wood product for visionary and fire safe buildings2016Proceedings (redaktörskap) (Refereegranskat)
    Abstract [en]

    Cross Laminated Timber uses the anisotropy of wood to its advantage by placing laminations across the grain. This elegant solution has led to Cross Laminated Timber (CLT or XLAM) being among the most significant recent innovations in timber engineering. It has grown to an economically significant area of R&D in wood sciences and has the ability to replace many traditional building products with a sustainable solution capable to answer the requests of our contemporary society, e.g. regional production, innovative and flexible designing possibilities, sustainability as well as safe design with respect to the building process and the final product.

    Invented in Mid Europe some decades ago, the most influential research and development of this product has also been based in Europe for a long time. This is challenged today, as other continents – having started work in this field later but as one joint effort – tend to overtake the European success story. The reasons for this are the known challenges within a unified Europe, very long standardization processes necessitating individual national approaches as well as competition within the timber construction sector rather than joint approaching of new markets.

    This conference has compiled knowledge about the material and its use, focusing on the design of CLT structures in ambient and fire situations. To this aim, two COST Actions – FP1402 Basis of structural timber design – from research to standards, and FP1404 Fire Safe Use of Bio-Based Building Products – joined efforts to provide contributions and presentations from world leading experts and to bring together expert communities to realize a scientific discourse on these important and interdisciplinary topics, leading to further joint harmonisation progression in research and development.

    This Joint Conference was meant to contribute to a high-quality and open scientific and technical dialogue within the timber community. The programme therefore included time for debate after the presentations as well as the formation of Think Tanks in which all participants, guided by essential questions, discussed the future challenges and development of CLT.

    During the Joint Conference, over 200 participants from the worldwide CLT community (ca. 50% coming from industry) showed their will to initiate joint work, concentrating strengths with respect to simplification, harmonisation and, most of all, understanding different points of views. This book contains not only the State-of-the-Art in research and practice, it also documents the valuable thoughts of experts on challenges and necessary developments of CLT within the next years.

  • 35.
    Falk, Andreas
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Function and design of innovative bio-based products for the building sector2016Ingår i: Structures and Architecture - Proceedings of the 3rd International Conference on Structures and Architecture, ICSA 2016, CRC Press/Balkema , 2016, s. 93-101Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper will present a study of preconditions for competitiveness in a resource saving society. Preconditions for material suppliers and industry versus requirements from legislation and consumers means a balance, which can be difficult to manage. The paper is aiming for an analysis of the preconditions for property modification, innovation and marketing of biobased materials and products, and the paper deals with strategies to release the architectural potential of bio-based construction. 

  • 36.
    Francart, Nicolas
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Hållbarhet, utvärdering och styrning.
    Erlandsson, Martin
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Malmqvist, Tove
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Hållbarhet, utvärdering och styrning.
    Larsson, Mathias
    Florell, Josefin
    Requirements set by Swedish municipalities to promote construction with low climate change impact2019Ingår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 208, s. 117-131Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study investigates how Swedish municipalities work to reduce the climate change impact of building construction. It focuses on current practices related to promoting the use of sustainable construction materials and on barriers to environmental requirements in construction, in particular environmental performance requirements based on LCA procedures. Municipalities were surveyed about the existence of municipal policies dealing with environmental issues in construction, the knowledge level about these issues, and the measures and requirements used to promote materials with low climate change impact. The survey was followed by semi-structured interviews about current practices and barriers to environmental requirements in construction. Results show that large municipalities are more likely to have dedicated policies and implement more measures than their smaller counterparts. However, willingness to implement future measures and knowledge of sustainable construction do not vary significantly with municipality population. Efforts are often limited to procurement, municipal construction projects and discussions with stakeholders. When requirements are set, they are almost always based on prescribing a technical solution (e.g. use of timber) rather than assessing environmental performance (e.g. calculating greenhouse gases emissions with a LCA tool). Measures that municipalities can take as public authorities are restricted by the law, which remains ambiguous as to the legality of environmental performance requirements. Legal issues, limited knowledge and resources appear to be the main barriers to environmental performance requirements in construction. A strategy is proposed to o​v​e​r​

  • 37.
    Frolovskaia, A. , V
    et al.
    Russia.
    Deordiev, S. , V
    Russia.
    Falk, Andreas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Klinduh, N. Y.
    Russia.
    Terehova, I. I.
    Russia.
    Experience of light thin-walled structures improvement in construction2018Ingår i: 6TH INTERNATIONAL CONFERENCE ON MECHATRONICS AND CONTROL ENGINEERING (ICMCE 2017), IOP PUBLISHING LTD , 2018, artikel-id UNSP 012004Konferensbidrag (Refereegranskat)
    Abstract [en]

    The authors on the basis of practical experience have analyzed low-rise construction with the use of energy-saving technologies. Characteristic features of possible variants of frame construction are looked at and described. The relevance of the paper consists in the improvement of the building frame design solution based on the analysis and elimination of disadvantages taking into account consumers' point of view.

  • 38.
    Fruchter, Renate
    et al.
    Stanford University.
    Krawinkler, Helmut
    Stanford University.
    Nilvér, Kjell
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Björnsson, Hans
    Chalmers.
    Tech-IQ: Technology Mediated Interdisciplinary Questioning2007Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The educational challenge of Tech IQ  is to assist students in developing an integrated understanding of  interdisciplinary, project-based teamwork through active participation in  inquiry.  To do this, the team will  create an innovative computer-mediated and question-driven learning experience.  Architecture, engineering, and management students engaged in project-based  learning typically apply their knowledge in discipline-centric inquiry, and  lack the opportunity to develop general interdisciplinary inquiry abilities in  a real-world project context.  The  research team will design, implement, test, deploy, and assess the Tech-IQ  learning interaction experiences as a pedagogic method based on a framework of  six degrees of question exploration in support of effective interdisciplinary  questioning in PBL. The team will use an information and communication  environment that leverages two of the most pervasive cognitive technologies,  i.e., speech and sketching. Using these tools will assist learners to  articulate and represent their thinking and questioning and make their level of  understanding more visible, tangible, clearer, sharable, and re-usable. These  tools will be deployed in the Architecture, Engineering, Construction  Management Global Teamwork course offered during 2006-07 at Stanford in collaboration  with KTH in Stockholm, Chalmers University  and IT University in Göteborg.

  • 39.
    Fruchter, Renate
    et al.
    Stanford University.
    Ponti, Marisa
    Göteborgs universitet.
    Krawinkler, Helmut
    Stanford University.
    Nilvér, Kjell
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Björnsson, Hans
    Chalmers.
    The Fishbowl: Degrees of Engagement in Global Teamwork2006Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The project team will improve cross-disciplinary, collaborative, and geographically distributive project-based learning (PBL) by creating an innovative, computer-mediated learning experience between  students and professionals working in the fields of architecture, engineering and construction management (AEC.) Faculty and researchers from Stanford, KTH, Chalmers and the IT University of Göteborg  will design, implement, test, deploy and evaluate a learning interaction  experience (“The Fishbowl”) as a pedagogical intervention  to support knowledge transfer from professionals to students. These  competencies include alternative ways to solve problems, inquiry  and negotiation skills, and probing the boundaries between disciplines.  Deliverables from this project will include a tested and evaluated  pedagogic model, an ICT-augmented workspace, deployed and tested  in PBL at Stanford, KTH, Chalmers and IT Göteborg, the implementation of the pedagogy and ICT in an AEC Teamwork course offered in spring 2006, evaluation of learning workspaces, and student learning  and  performance assessments.

  • 40. García, A.
    et al.
    Norambuena-Contreras, J.
    Bueno, M.
    Partl, Manfred
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial. Empa, Swiss Federal Laboratories for Materials Science and Technology, Duebendorf, Switzerland .
    Influence of steel wool fibers on the mechanical, termal, and healing properties of dense asphalt concrete2014Ingår i: Journal of Testing and Evaluation, ISSN 0090-3973, E-ISSN 1945-7553, Vol. 42, nr 5Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper summarizes the main results of experimental research on the induction healing of dense asphalt concrete with steel wool fibers. Different physical properties of dense asphalt concrete, as the steel wool fibers distribution, mechanical properties, thermal conductivity, and healing via induction heating have been analysed. The main results show that short and thick fibers disperse very well in the mixture, while long and thin fibers produce clusters. It was also observed that fibers can be damaged during the mixing and compaction processes. In addition, it was found that steel wool fibers do not significantly improve the mechanical properties and damage resistance of dense asphalt concrete. Moreover, steel wool fibers slightly increase the thermal conductivity of dense asphalt concrete. Furthermore, the temperature reached due to induction heating increases with the number of fibers in the mixture and with their diameter. Finally, it was found that dense asphalt concrete heals through the increase of temperature and that the type and diameter of fibers do not influence the healing properties of dense asphalt concrete.

  • 41.
    Gardner, D. J.
    et al.
    University of Maine.
    Tascioglu, C
    Wålinder, M. E. P.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Wood composite protection2003Ingår i: Wood Deterioration and Preservation / [ed] B. Goodell, D. Nicholas, and T.P. Schultz,, American Chemical Society , 2003, s. 399-419Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Wood composites should be protected against microbial and insect attack when used outdoors, especially in construction applications with prolonged exposure to moisture. Preservative systems and treatment processes affect composite properties, especially adhesive/wood bonding and mechanical properties. Several common systems for preservation of composites include, 1) the use of pretreated wood, applicable particularly to some solid lumber laminates; 2) in-process preservative treatments favored for composites made from flakes, particles, and fibers where the preservative treatment is incorporated during the manufacturing process; 3) post-process preservative treatments which are generally favored for wood composites made from lumber and veneer; and 4) the use of recycled treated wood elements in manufacturing or the use of wood species with a high natural resistance against biodegradation. This chapter discusses these four preservative methods and presents a general overview of current research concerning preservation practices and techniques in North America including the effect of preservatives on composite properties, durability issues, and degradation modes.

  • 42.
    Ghafoori Roozbahany, Ehsan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Flow behavior of asphalt mixtures under compaction2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Asphalt compaction is one of the most important phases of road construction, being the decisive phase when the structure of the asphalt pavement layer is formed. In spite of its importance, the knowledge about this construction phase is still based on empirical and technological background and therefore surprisingly limited. This lack of knowledge is also due to the fact that the existing laboratory scale compaction devices for mix design are not fully capable of simulating the field compaction. The simulation of asphalt compaction in the laboratory is normally focused on the vertical rearrangements of asphalt particles whereas the flow behavior of these particles in other directions is mostly neglected. However, existing literature suggests that the neglected flow is one of the most important factors for the quality of the road construction, particularly in special cases such as asphalt joints. Therefore, building up a better understanding of the flow behavior of asphalt mixtures subjected to compaction loads is needed for improving the quality of the pavements.

    In this study, a new test setup, the so called Compaction Flow Test (CFT), was developed to simulate the flow behavior of asphalt mixtures at early stages of compaction. In the first step, feasibility tests were performed, substituting asphalt mixtures by model materials with simple geometries and less complex properties. X-ray Computed Tomography (CT) was utilized for capturing 2D radiography images of the flow patterns in the model material during the test. Results of the CFT showed the capability of the new test setup to clearly distinguish between model mixtures with different characteristics. Hence, in the next step, the CFT was applied to real asphalt mixtures and the obtained results were found to support the findings of the feasibility tests with the model materials.

    The results from the feasibility tests encouraged examining the possible use of an ultrasonic sensor as alternative to the complex and costly X-ray imaging for flow measurements during the CFT. Hence, the CFT was used along with a distance measuring ultrasonic sensor for testing asphalt mixtures with different characteristics. The test results confirmed that an ultrasonic sensor could be effective for capturing the differences of the flow behavior of asphalt mixtures tested by the CFT. 

    In addition, a parametric study with the X-ray setup was carried out to examine the capability of the CFT in reflecting the possible changes of the flow behavior in asphalt mixtures due to the change of construction parameters such as lift thickness, bottom roughness and compaction modes. The results obtained also confirmed the capability of the CFT in showing the possible differences in the flow behavior of the mixtures under the chosen conditions.

    The encouraging results suggested that the CFT may have potential to become a simple but effective tool for assessing compactability of the mixtures on-site, right after production in an asphalt plant or before placing the mixture on the road. Hence, discrete element method (DEM) was utilized to understand both the influence of selected boundaries of the CFT and the effect of its design on the results.

    As one specific example of application, an investigation was carried out using the CFT to find the most suitable tracking method for flow measurements in the field. Based on the literature review and feasibility tests, a tracking method with the highest potential for conducting flow measurements during field compaction was introduced. X-ray radiography confirmed the validity of the results obtained with the suggested method.

    The overall results obtained from this study suggest that the recommended CFT along with the suggested field tracking method may be helpful in building up a comprehensive basis of knowledge on the flow and compaction behavior of asphalt mixtures thus helping to close the gap between the field and laboratory.

  • 43.
    Ghafoori Roozbahany, Ehsan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Investigation of asphalt compaction in vision of improving asphalt pavements2015Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Asphalt joints are potentially weakest parts of every pavement. Despite of their importance, reliable tools for measuring their mechanical properties for design and performance assessments are still scarce. This is particularly true for cold joints when attaching a new hot pavement to a cold existing one as in case of large patches for pavement repair. In this study, three static fracture testing methods, i.e. indirect tensile test (IDT), direct tension test (DTT) and 4 point bending (4PB), were adapted and used for evaluating different laboratory made joints. The results suggested that joints with inclined interfaces and also the ones with combined interface treatments (preheated and sealed) seemed to show more promising behaviors than the vertical and untreated joints. It was also confirmed that compacting from the hot side towards the joint improved the joint properties due to imposing a different flow pattern as compared to the frequent compaction methods. The latter finding highlighted the importance of asphalt particle rearrangements and flow during the compaction phase as a very little known subject in asphalt industry. Studies on compaction are of special practical importance since they may also contribute to reducing the possibility of over-compaction and aggregate crushing.

    Therefore, in this study, a new test method, i.e. Flow Test (FT), was developed to simulate the material flow during compaction. Initially, asphalt materials were substituted by geometrically simple model materials to lower the level of complexity for checking the feasibility of the test method as well as modeling purposes. X-ray radiography images were also used for capturing the flow patterns during the test. Results of the FT on model materials showed the capability of the test method to clearly distinguish between specimens with different characteristics. In addition, a simple discrete element model was applied for a better understanding of the test results as a basis for further improvements when studying real mixtures. Then, real mixtures were prepared and tested under the same FT configuration and the results were found to support the findings from the feasibility tests. The test method also showed its potential for capturing flow pattern differences among different mixtures even without using the X-ray. Therefore, the FT was improved as an attempt towards developing a systematic workability test method focusing on the flow of particles at early stages of compaction and was called the Compaction Flow Test (CFT).

    The CFT was used for testing mixtures with different characteristics to identify the parameters with highest impact on the asphalt particle movements under compaction forces. X-ray investigations during the CFT underlined the reliability of the CFT results. In addition, simple discrete element models were successfully generated to justify some of the CFT results.

  • 44.
    Ghafoori Roozbahany, Ehsan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Modelling the flow behavior of asphalt under simulated compaction using discrete elementIngår i: Materials and DesignArtikel i tidskrift (Refereegranskat)
    Abstract [en]

    The flow differences between the particles of asphalt mixtures compacted in the laboratory and in the field have been identified as one of the reasons for the discrepancies between laboratory and field results. In previous studies, the authors developed a simplified test method, the so-called compaction flow test (CFT), for roughly simulating the flow of particles in asphalt mixtures under compacting loads under laboratory conditions. The CFT was used in different studies to examine its capability of revealing the differences between the flow behavior of different asphalt mixtures under different loading modes. The promising results encouraged further development of the CFT by investigating the impact of simplifications and boundary conditions on the results of the test. For this reason, discrete element method (DEM) was utilized and the possible impacts of the mold size as well as the shape of the loading strip on the results of the CFT were simulated for a mixture with extreme idealized aggregate structure. The results indicate that in case of wearing course layers with a single size gradation of 11mm spheres, the length of the CFT mold can be increased from 150mm to 200-250mm for reducing disturbances from walls of the mold. However, since the majority of the flow is expected to take place within the first 100-150mm length of the mold, reasonable results are obtained even without changing the size of the CFT mold. Moreover, comparing results with different loading strip geometries and loading rates indicates that the current CFT setup still appears to provide consistent results.    

  • 45.
    Ghafoori Roozbahany, Ehsan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Partl, Manfred
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    A new test to study the flow of mixtures at early stages of compaction2016Ingår i: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 49, nr 9, s. 3547-3558Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Workability is one of the most commonly used indicators for the capability of asphalt mixtures tobe placed and compacted on the roads with long lasting quality and minimum maintenancethroughout its service life. Despite of valuable previous efforts for measuring and characterizingworkability, none of them has proven successful in representing the field conditions of roadconstructions. This paper is an attempt towards developing a systematic workability test methodfocusing on compaction, the so-called Compaction Flow Test (CFT), by simulating fieldcompaction at early stages and at laboratory scale with the main focus on mixture flow. The CFTwas applied for different mixtures in order to identify the parameters with highest impact on theasphalt particle movements under compaction forces. A new setting inside X-ray ComputationalTomography (CT) allowed tracing asphalt particles during the CFT and acquiring CT imagesunderlining the reliability of the CFT results. In addition, simple Discrete Element Models (DEM)were successfully generated to justify some of the CFT results.

  • 46.
    Ghafoori Roozbahany, Ehsan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Partl, Manfred
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Investigation of asphalt joint compaction using discrete element simulation2019Ingår i: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Constructing high quality asphalt joints plays a vital role in preventing premature failures of pavements. Previous studies suggested that many construction parameters directly and indirectly influence the quality of asphalt joints. Due to uncertainties about the influence of each parameter on the quality of the finalised joints, closer and more detailed studies are still needed for achieving further improvements in this field. This study investigates the possible impacts of thickness, bottom layer roughness, joint interface geometries and compaction techniques on the particle flow of a coarse structured mixture during compaction. Therefore, discrete element method (DEM) was utilised to evaluate the influence of each construction parameter on the interlock between the cold and the hot side of an asphalt pavement joint. The results helped to explain earlier experimental findings about the joints and revealed potential for further laboratory and field investigations.

  • 47.
    Ghafoori Roozbahany, Ehsan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial. VTI Swedish National road and transport research institute, Olaus Magnus väg 35, Linköping, 583 30, Sweden.
    Partl, Manfred
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Elaguine, Denis
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Modelling the flow of asphalt under simulated compaction using discrete element2019Ingår i: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 227, artikel-id 116432Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The flow differences between the particles of asphalt mixtures compacted in the laboratory and in the field have been identified as one of the reasons for the discrepancies between laboratory and field results. In previous studies, the authors developed a simplified test method, the so-called compaction flow test (CFT), for roughly simulating the flow of particles in asphalt mixtures under compacting loads in laboratory. The CFT was used in different studies to examine its capability of revealing the differences between the flow behavior of different asphalt mixtures under various loading modes. The promising results encouraged further development of the CFT by investigating the possible impacts of simplifications and boundary conditions on the results of this test. For this reason, discrete element method (DEM) was utilized to investigate possible impacts of the mold size, geometry of the loading strip as well as the loading rate on the results of the CFT. The results of the simulation indicate that in case of wearing course layers with nominal maximum aggregate size of 11 mm, the length of the CFT mold can be increased from 150 mm to 200–250 mm for reducing flow disturbances from the mold walls. However, since the majority of the flow of asphalt mixture particles is expected to take place within the first 100–150 mm length of the mold, reasonable results can still be obtained even without changing the size of the CFT mold. Moreover, comparing results with different loading strip geometries and loading rates indicates that the current CFT setup still appears to provide consistent results.

  • 48.
    Ghafoori Roozbahany, Ehsan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Partl, Manfred
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Guarin, Alvaro
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Influence of layer thickness on the flow of asphalt under simulated compaction2018Ingår i: Bearing Capacity of Roads, Railways and Airfields - Proceedings of the 10th International Conference on the Bearing Capacity of Roads, Railways and Airfields, BCRRA 2017, CRC Press/Balkema , 2018, s. 1435-1441Konferensbidrag (Refereegranskat)
    Abstract [en]

    Compaction is one of the most important phases in the life cycle of asphalt pavements and has therefore been a hot subject of research for a long time. However, despite of valuable research efforts on this topic, a remarkable gap between laboratory and field measurements still remains. Moreover, whereas most of the experimental methods are carried out on compacted pavement material, methods for evaluating compactability of asphalt mixtures for increasing the fundamental knowledge about internal movements within the asphalt during compaction are only scarce. Hence, in this study, a recently developed tool for simulating the compaction process with respect to the particle flow, i.e. Compaction Flow Test (CFT), was used along with simultaneous X-ray imaging for investigating the impact of thickness changes on two different asphalt mixture structures in terms of the compaction effort as well as flow pattern differences. The results of the investigation provided reasonably useful input for building up a better understanding of the behavior of mixtures under compaction loads. This method was able to successfully reveal the differences of the structural rearrangements within the asphalt mixtures for three different lift thicknesses. It also helped to explain some of the previous research studies results in a more comprehensive way. The achievements of this study may serve for developing an in-site evaluating test method for assessing compactability of asphalt mixtures before placing them on the roads.

  • 49.
    Ghafoori Roozbahany, Ehsan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Partl, Manfred
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Guarin, Alvaro
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Introducing a new method for studying the field compaction2017Ingår i: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 18, s. 26-38Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The flow of particles during compaction may have a prominent influence on the difference of field and laboratory results as recently demonstrated by the authors with their newly developed compaction flow test (CFT). This test with a simple compaction simulator was used for studying the flow behaviour and rearrangement of particles for mixtures with different structures and thicknesses. However, validating the CFT results for practical purposes requires field measurements that provide more insight into the compaction process and eventually allowing to adjust the CFT for further use as an evaluating in-site tool. This study presents a new method for conducting such measurements during field compaction. In this method, some representative particles are tracked inside asphalt specimens and the accuracy of the results is examined by X-ray computed tomography. The results of the feasibility tests show that this method has potential for further use in the field and for building up a comprehensive basis of knowledge on field compaction towards closing the gap between the field and laboratory results.

  • 50.
    Ghafoori Roozbahany, Ehsan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Partl, Manfred N.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Guarin, Alvaro
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Particle Flow during Compaction of Asphalt Model Materials2015Ingår i: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 100, nr 15, s. 273-284Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Compaction is one of the key phases of the pavement construction and has been subject of research for a long time. However, very little is known regarding what really happens during compaction and how the pavement structure and the aggregate skeleton of the asphaltic layer are formed. Studies on that matter are of special practical importance since they may contribute to reduce the possibility of over-compaction and aggregate crushing. In this study, a new test method (Flow Test) was developed to simulate the material flow during compaction. Initially, asphalt materials were substituted by model materials to lower the level of complexity for checking the feasibility of the new test method as well as modeling purposes. Geometrically simple materials with densest possible combinations were tested for both dry and coated mixtures. X-ray radiography images were used for evaluating the material flow during compaction for different model mixtures. Results showed the capability of the test method to clearly distinguish mixtures with different properties from one another and also the potential of such a method to be used as an evaluating tool in the field. In addition, a simple discrete element model was applied for better understanding the flow of the model material during compaction as a basis for further improvement when moving from the asphalt model material to real mixtures. Therefore, real mixtures were prepared and tested under the same test configuration as for the model materials. The overall results of the real mixtures were found to support the model material test results.

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