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  • 1.
    Ansell, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Bryne, Lars Elof
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    In situ observations and laboratory testing of shrinkage cracking in shotcrete on soft drains2015Conference paper (Refereed)
    Abstract [en]

    In Scandinavian traffic tunnels soft drains covered with shotcrete are often installed to lead away un-wanted water, giving little resistance to shotcrete shrinkage, which may cause severe cracking. Mapping of shrinkage cracks was done in situ, followed by analyses focused on stresses due to drying shrinkage and various time of waiting between turns of spraying, with or without water curing. The effect of dilatation joints has also been investigated. A recently developed laboratory test set-up with shotcrete on instrumented granite slabs represent shrinkage of shotcrete on soft drains. The test results indicate that addition of glass fibres could reduce the cracking problem.

  • 2.
    Ansell, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Bryne, Lars Elof
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Laboratory evaluation of shrinkage in shotcrete sprayed on soft drains2014Conference paper (Refereed)
  • 3.
    Ansell, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Bryne, Lars Elof
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Holmgren, Jonas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Testing and evaluation of shrinkage cracking in sprayed concrete on soft drains2014Conference paper (Refereed)
  • 4.
    Bryne, Lars Elof
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Investigation and development of material properties for shotcrete for hard rock tunnels2014Report (Other academic)
  • 5.
    Bryne, Lars Elof
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Time dependent material properties of shotcrete for hard rock tunnelling2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis different mechanical properties for shotcrete (sprayed concrete) such as compression strength, bond strength, bending tensile strength, elastic modulus, free and restrained shrinkage as a function of its age was investigated. One of the main issues was to investigate the difference between ordinary cast concrete and shotcrete. Reliable material data for young and hardening shotcrete is scarce which in the past have made such comparisons difficult. Also, less accurate data representative for cast concrete has often been used in numerical modelling and design analyses. The focus of the project has particularly been on the properties bond strength and restrained shrinkage for which two new testing methods has been developed and evaluated. Microstructural studies have also been performed as a complement to the bond strength testing.

    The bond to rock is one of the most important properties for shotcrete used as rock reinforcement. During the very first time after spraying the physical properties and the bond to the rock depend on the set accelerator and the micro structure that is formed. The investigation of early age bond strength of shotcrete is of great importance both from a production perspective and a safety perspective. The newly developed method was tested and evaluated and proved that it can be used for bond strength testing already from a couple of hours after shotcreting. The bond, or adhesion, depends on several factors such as texture of the rock, the type of accelerator, application technique, etc. In this work the development of the microstructure in the interfacial transition zone (ITZ) and strength of the bond was investigated. The results show that the bond strength is related to the hydration process, i.e. the strength gain of the shotcrete. The early development of the ITZ was here studied using a scanning electron microscope (SEM) making it possible to observe changes over time, before and after proper cement hydration.

    Restrained shrinkage cracking of shotcrete, especially in the case of shotcrete sprayed on soft drains that are parts of a tunnel lining not continuously bonded to the rock, can be detrimental for the sustainability of an infrastructure tunnel system. Maintenance and repair costs can be high over time. It is shown that the developed test method realistically captures the behaviour of shotcrete drains on hard rock in situ. The method can be used in the evaluation of different technical solutions for avoiding or minimizing shrinkage cracks in shotcreted soft drains. It can also be used to assess the performance of shotcrete fully bonded to a rock surface, with respect to the ability to prevent cracking or to distribute possible shrinkage damage into several fine cracks instead of one wide.

    Download full text (pdf)
    Thesis
  • 6.
    Bryne, Lars Elof
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Laboratory testing of early age shotcrete bond strength2014Conference paper (Refereed)
  • 7.
    Bryne, Lars Elof
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Restrained shrinkage tests of fibre concrete for shotcrete applications in hard rock tunnels2011In: Nordic Concrete research: Research projects 2011 / [ed] D.H. Bager, Oslo: The Nordic Concrete Federation , 2011, p. 489-492Conference paper (Refereed)
  • 8.
    Bryne, Lars Elof
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Vidhäftningshållfasthet hos sprutbetong på hårt berg2015In: Bygg och Teknik, ISSN 0281-658X, E-ISSN 2002-8350, no 7, p. 20-26Article in journal (Other (popular science, discussion, etc.))
  • 9.
    Bryne, Lars Elof
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Holmgren, Jonas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Early age bond strength between hard rock and hardening shotcrete2014Conference paper (Refereed)
  • 10.
    Bryne, Lars Elof
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Holmgren, Jonas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Investigation of restrained shrinkage cracking in partially fixed shotcrete linings2014In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 42, p. 136-143Article in journal (Refereed)
    Abstract [en]

    This study investigates shrinkage of accelerated shotcrete (sprayed concrete), especially in the case of shotcrete sprayed on drains, a part of a tunnel lining not continuously bonded to the rock. One of the goals is to find methods of avoiding shotcrete shrinkage cracks in such drain structures. If cracks yet develop the crack distribution is of great importance, i.e. several fine cracks instead of one wide. By using both steel and glass fibres this may be achieved. A newly developed test set-up for shrinking, end-restrained shotcrete slabs is also presented and evaluated. The performed tests show that the addition of very fine glass fibres could be a solution to the cracking problem. The newly developed test equipment using concrete interacting with an instrumented granite slab represents a realistic way of testing restrained shrinkage. The on-going research focuses on the optimization of the glass fibre addition and the understanding of the interaction between shrinkage and creep of shotcrete.

  • 11.
    Bryne, Lars Elof
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Holmgren, Jonas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Shrinkage testing of end-restrained shotcrete on granite slabs2014In: Magazine of Concrete Research, ISSN 0024-9831, E-ISSN 1751-763X, p. 1300348-Article in journal (Refereed)
    Abstract [en]

    This study investigated the shrinkage of shotcrete (sprayed concrete), especially the case of shotcrete sprayed on drains – a part of tunnel lining not continuously bonded to the rock. A newly developed method for testing the shrinkage of end-restrained shotcrete slabs is presented and evaluated. The test setup, which is designed to capture in situ behaviour, consists of shotcrete sprayed on an instrumented granite slab partly covered with a plastic sheet. The primary goal was to practically use and evaluate the test method with shotcreted test samples. Results from restrained shrinkage tests are presented along with results for free shrinkage. It is shown that the method realistically captures the behaviour of shotcrete drains on hard rock in situ. In addition, the corresponding compressive strength and flexural crack strength as functions of shotcrete age are also reported. The test method can be used for an evaluation of different solutions for avoiding shrinkage cracks in shotcreted soft drains, or in shotcrete that is fully bonded to a rock surface, with respect to preventing cracking or distributing the shrinkage strain into several fine cracks instead of one wide crack.

  • 12.
    Bryne, Lars Elof
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Holmgren, Jonas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Experimental investigation of the bond strength between rock and hardening sprayed concrete2011In: Sprayed concrete: Modern use of wet mix sprayed concrete for underground support / [ed] T. Beck, O. Woldmo & S. Engen, Oslo: Norwegian Concrete Association , 2011, p. 77-88Conference paper (Refereed)
  • 13.
    Bryne, Lars Elof
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Lagerblad, Björn
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Interfacial Transition Zone between Young Shotcrete and Hard Rock2022In: ACI Materials Journal, ISSN 0889-325X, E-ISSN 1944-737X, Vol. 119, no 5, p. 3-9Article in journal (Refereed)
    Abstract [en]

    Shotcrete (sprayed concrete) differs from ordinary cast concrete through the application technique and the addition of set accelerators that promote immediate stiffening. The bond strength development between shotcrete and rock is an important property that depends on the texture of the rock, the type of accelerator, and application technique. This investigation focuses on the development of the microstructure in the interfacial transition zone (ITZ) and the strength of the bond at the shotcrete-hard rock boundary. The results show that the bond strength is related to the hydration process—that is, the strength gain of the shotcrete—and remains low before the acceleration period of the cement hydration. With a scanning electron microscope (SEM), it is possible to observe changes over time for the early development of the interfacial zone, both before and after proper cement hydration. Results from tests with wet-sprayed concrete on granite rock are presented. The test method—using both bond strength and the SEM to investigate the development of the microstructure at the ITZ—is interesting, but has to be more broadly examined. Different mixtures, accelerators, and rock types have to be used.

  • 14.
    Bryne, Lars Elof
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Lagerblad, Björn
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Interfacial transition zone between young shotcrete and hard rock2022Manuscript (preprint) (Other academic)
    Abstract [en]

    Shotcrete (sprayed concrete) differs from ordinary cast concrete through the application technique and the addition of set accelerators that promote immediate stiffening. The bond strength development between shotcrete and rock is an important property that depends on the texture of the rock, the type of accelerator, and application technique. This investigation focuses on the development of the microstructure in the interfacial transition zone (ITZ) and the strength of the bond at the shotcrete-hard rock boundary. The results show that the bond strength is related to the hydration process—that is, the strength gain of the shotcrete—and remains low before the acceleration period of the cement hydration. With a scanning electron microscope (SEM), it is possible to observe changes over time for the early development of the interfacial zone, both before and after proper cement hydration. Results from tests with wet-sprayed concrete on granite rock are presented. The test method—using both bond strength and the SEM to investigate the development of the microstructure at the ITZ—is interesting, but has to be more broadly examined. Different mixtures, accelerators, and rock types have to be used.

  • 15.
    Bryne, Lars Elof
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Lausamaa, J.
    Ernstsson, M.
    Englund, Finn
    Wålinder, Magnus
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Söderström, Ove
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    UV-laser irradiated wood: Some aspects on micromorphology, wettability, surface composition and liquid permeability2008In: Proceedings of the 4th meeting of the Nordic-Baltic network in wood material science and engineering (WSE), 2008, p. 75-82Conference paper (Refereed)
    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.

  • 16.
    Bryne, Lars Elof
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures. Vattenfall AB R&D, Älvkarleby, Sweden.
    Nordström, Erik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures. Vattenfall AB R&D, Älvkarleby, Sweden.
    Expansion-joints in concrete dams2023In: 91st Annual ICOLD Meeting, Gothenburg, Sweden, 13-14 June 2023: Management for Safe Dams / [ed] Erik Nordström, Stockholm, 2023Conference paper (Refereed)
    Abstract [en]

    Hydro power facilities in Sweden are in general exposed to large temperature variations betweensummer and winter, high moisture levels and high hydrostatic pressure on water retaining structures.In concrete structures with insufficient properties these factors co-operate and can result indegradation by e.g., frost action, erosion, leaching and stresses that can aggravate leakage of waterand further degradation or cracking of the concrete material. In concrete dams and hydro power plants different kind of joints are installed. Cold joints anddilatation joints are two common types. Dilatation joints must be designed and constructed sothey are both water retaining and flexible enough to follow thermal movements of the concretewithout rupturing. A joint that is not well constructed with a good performance can jeopardize thedam safety for a hydro power facility with uncontrolled leakage, ice-formation, degradation orproblematic erosion on the down-stream side. A laboratory study of concrete from an dilatation joint has been performed in this project. Thestudied materials are taken from a larger concrete slab of a spillway sill of a concrete dam. Thescope of the project has been to study the characteristics of the concrete around the water stop anddilatation joint. The goal was to learn more about the mechanisms behind the degradation andleaking of expansion joints.

  • 17.
    Bryne, Lars-Elof
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Aspects on wettability and surface composition of modified wood2008Licentiate thesis, comprehensive summary (Other scientific)
    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.

    Download full text (pdf)
    FULLTEXT01
  • 18.
    Bryne, Lars-Elof
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Laboratory testing of early age bond strength between concrete for shotcrete use and rock2013In: Nordic Concrete Research, ISSN 0800-6377, Vol. 47, p. 81-100Article in journal (Refereed)
    Abstract [en]

    Shotcrete(sprayed concrete) is, together with rock bolts, the most important material used for reinforcement in hard rock tunnelling. Sprayed concrete differs from ordinary concrete through the application technique and the addition of accelerators which give immediate stiffening. The bond between sprayed concrete and rock is one of the most important properties in the quality assessment of shotcreted concrete. During the very early age after spraying the physical properties of the concrete and the bond to the rockdepend on the accelerator and the micro structure that is formed. In this work a laboratory test method for measuring early bond strength for very young shotcrete is presented.

  • 19.
    Bryne, Lars-Elof
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Laboratory testing of the bond strength between shotcrete and rock2012In: fib Symposium 2012: Concrete Structures for Sustainable Community - Proceedings, 2012, p. 433-436Conference paper (Refereed)
    Abstract [en]

    Sustainable tunnel constructions in hard rock depend on efficient reinforcement systems but reliable material parameters are, however, not always available for shotcrete (sprayed concrete). Therefore, parameters for ordinary, cast concrete are often used in the design of structural shotcrete. Shotcrete differs from ordinary concrete through its application technique and the addition of accelerators which gives rapid hardening. Early after spraying the material properties of shotcrete, including the bond to the rock, depend on the accelerator and the micro structure formed. In this project the development of bond strength as a function of age for very young shotcrete is studied.

  • 20.
    Bryne, Lars-Elof
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Holmgren, Jonas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Laboratory testing of early age bond strength of shotcrete on hard rock2014In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 41, no 1, p. 113-119Article in journal (Refereed)
    Abstract [en]

    This study investigates early age bond strength of shotcrete (sprayed concrete), in the case of shotcrete sprayed on hard rock. Shotcrete differs from ordinary, cast concrete through the application technique and the addition of set accelerators which give immediate stiffening. The bond between shotcrete and rock is one of the most important properties. During the very first time after spraying the physical properties and the bond to the rock depend on the set accelerator and the micro structure that is formed. In this work a laboratory test method for measuring early bond strength for very young or early age shotcrete is presented. The newly developed method was tested and evaluated and proved that it can be used for bond strength testing already from a couple of hours after shotcreting.

  • 21.
    Bryne, Lars-Elof
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Lagerblad, Björn
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Texture and bond at the interfacial zone between rock and sprayed concrete2012In: fib Symposium 2012: Concrete Structures for Sustainable Community - Proceedings, 2012, p. 605-608Conference paper (Refereed)
    Abstract [en]

    Sprayed concrete differs from ordinary concrete through the application technique and the additions of accelerators that gives immediate stiffening. The bond between sprayed concrete and rock is an important property. This work has investigated the development of the microstructure in the interfacial zone and strength of the bond. The results show that the bond strength is related to the strength gain of the concrete. Before the acceleration period of the cement hydration the bond strength is very low. As regard the early development of the interfacial zone, it is in SEM possible to observe changes over time both before and after proper cement hydration.

  • 22.
    Bryne, Lars-Elof
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    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, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Ageing of modified wood: Part 2: Determination of surface composition of acetylated, furfurylated, and thermally modified wood by XPS and ToF-SIMS2010In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 64, no 3, p. 305-313Article in journal (Refereed)
    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.

  • 23.
    Bryne, Lars-Elof
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Wålinder, Magnus
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Ageing of modified wood: Part 1: Wetting properties of acetylated, furfurylated, and thermally modified2010In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 64, no 3, p. 295-304Article in journal (Refereed)
    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.

  • 24.
    Englund, F.
    et al.
    Technical Research Institute of Sweden.
    Bryne, Lars Elof
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Ernstsson, M.
    Institute for Surface Chemistry, Stockholm, Sweden.
    Lausmaa, J.
    SP Technical Research Institute of Sweden.
    Wålinder, Magnus
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Spectroscopic studies of surface chemical composition and wettability of modified wood2009In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 4, no 1-2, p. 80-85Article in journal (Refereed)
    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.

  • 25.
    Englund, F.
    et al.
    Technical Research Institute of Sweden.
    Bryne, Lars-Elof
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Ernstsson, Marie
    Institute for Surface Chemistry, Stockholm, Sweden.
    Lausmaa, J
    SP Technical Research Institute of Sweden.
    Wålinder, M. E. P.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Some Aspects on the Determination of Surface Chemical Composition and Wettability of Modified Wood2009In: 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, p. 553-560Conference paper (Refereed)
  • 26.
    Wålinder, M. E. P.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Bryne, Lars-Elof
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Wood adhesion mechanisms: prediction of wood-thermoplastic-water interactions2006In: Wood Adhesives 2005 / [ed] Charles R. Frihart, Forest Products Society , 2006, no 7230, p. 385-392Conference paper (Refereed)
1 - 26 of 26
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