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  • 1.
    Ahmed, Lamis
    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.
    Malm, Richard
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Numerical modelling and evaluation of laboratory tests with impact loaded young concrete prisms2016In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, ISSN 1359-5997, Vol. 49, no 11, p. 4691-4704Article in journal (Refereed)
    Abstract [en]

    Numerical modelling in combination with in situ measurements, observations and laboratory testing will be important to future establishment of reliable guidelines for efficient civil and engineering work involving concrete casting close to e.g. blasting operations. Results from laboratory tests with impact loaded young concrete prisms are here evaluated using a 3D finite element model. Solid elements are used and a non-linear material model implemented, capable of describing cracking during stress wave propagation. The position of cracks and measured particle vibration velocities are calculated and compared with laboratory test results. The damaging effect of impact vibrations is evaluated using crack width and fracture energy as damage criteria. Alternative geometry for the test prisms, with a notched section, is analysed. This will give one wide crack at the centre of the prism instead of two or three cracks distributed over its length which will make future laboratory test more efficient and reliable. Recommended damage limits at concrete ages of 4, 6, 8 and 12 h are given, based on numerical calculations for concrete strength class C25 and C50.

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  • 2. Arraigada, M
    et al.
    Partl, Manfred
    Swiss Federal Laboratories for Materials Testing and Research (EMPA).
    Angelone, S
    Martìnez, Francisco
    Evaluation of Accelerometers to Determine Pavement Deflections under Traffic Loads2008In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 42, no 6, p. 779-790Article in journal (Refereed)
    Abstract [en]

    The purpose of this work was to study the use of accelerometers to measure pavement deflections due to traffic loads. To this end, accelerometers were embedded in two sites: the full scale load simulator Circular Test Track (CTT) and the A1 motorway in Switzerland. Deflections were derived from acceleration measurements using an algorithm that double integrates the measured signal and corrects any errors derived from the procedure. In the motorway, deflections were monitored using a set of three magnetostrictive deflectometers. Additionally, the pavement's material viscoelastic parameters determined in the laboratory were incorporated in Finite Element (FE) models to estimate the theoretical deflections. The calculated deflections were then compared to the measured and to the theoretical deflections. Deflections calculated from acceleration showed a reasonable qualitative correlation to those measured by magnetostrictive deflectometers. In addition, the FE models revealed the inability of the accelerometers to measure very slow or quasi-static motion.

  • 3.
    Bagampadde, Umaru
    et al.
    Makerere University, Kampala.
    Isacsson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Kiggundu, Bob
    Makerere University, Kampala.
    Impact of bitumen and aggregate composition on stripping in bituminous mixtures2006In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 39, no 287, p. 303-315Article in journal (Refereed)
    Abstract [en]

    The impact of bitumen and aggregate composition on stripping was investigated using four bitumens and four aggregates. Moisture sensitivity was assessed based on retained resilient modulus and tensile strength ratio (MRR and TSR, respectively). The results indicate that mixtures from the bitumen with a high acid number exhibited high resilient modulus and tensile strength in the dry condition for all the aggregates. In wet condition, this conclusion did also hold except for one aggregate. Regarding penetration grade, mixtures made with lower penetration grade bitumen exhibited higher resilient modulus and tensile strength, in dry and wet conditions, than those of higher penetration grade. Bitumen characteristics like acid number, penetration grade and molecular size distribution did not influence moisture sensitivity. Mixtures with aggregates containing alkali metals (sodium and potassium) exhibited relatively high moisture sensitivity, regardless of the bitumen used. In contrast, indications of moisture sensitivity were not apparent in mixtures made with aggregates containing calcium, magnesium and iron. Data analysis revealed that variability in moisture sensitivity is attributed to aggregate rather than bitumen. No significant interaction effect between bitumen and aggregate was found on moisture sensitivity. The results indicated good correlation between MRR and TSR in ranking mixtures for stripping.

  • 4.
    Billberg, Peter
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Time-Dependent Growth of Static and Dynamic Yield Stress of SCC2006In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873Article in journal (Other academic)
  • 5.
    Birgisson, Björn
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering.
    Montepara, Antonio
    Romeo, Elena
    Roncella, Riccardo
    Roque, Reynaldo
    Tebaldi, Gabriele
    An optical strain measurement system for asphalt mixtures2009In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 42, no 4, p. 427-441Article in journal (Refereed)
    Abstract [en]

    Knowledge of the conditions governing the initiation and propagation of cracks in hot mix asphalt (HMA) mixtures is a prerequisite for a comprehensive understanding of HMA cracking mechanisms. Traditional strain measurement sensors have proved to be not completely adequate in the sense that they do not provide pointwise measurements, thus not pinpointing the location of crack initiation, and not accounting for non-uniform strain distributions. This paper presents a digital image correlation (DIC) system for non-contact and full strain field measurements, conceived for the purpose of investigating the cracking behavior of HMA mixtures. The whole system was developed so as to account for the special nature of typical HMA testing configurations. An image matching technique (least squares matching) was employed for providing matches with sub-pixel accuracy. The performance of the method was investigated by several tests. The DIC system was shown to overcome the shortcomings of traditional on-specimen strain measurement devices achieving satisfactory accuracy compared to strain gauges.

  • 6.
    Björk, Folke.
    et al.
    KTH, Superseded Departments (pre-2005), Civil and Architectural Engineering.
    Granne, F.
    Roof membranes - The Swedish practice in light of EOTA TB 97/24/9.3.1 PT3 durability2000In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 33, no 228, p. 270-277Article in journal (Refereed)
    Abstract [en]

    The practice for roof membranes for flat and low-slope roofs has substantially developed during the last two decades of the twentieth century. New technical solutions have been introduced and building codes and guidelines have been changed. The development of technical solutions preceded the scientific work. However, the scientific work did help to develop the technical practice for enhanced performance. The development described in this paper has much in common with recently published EOTA-guidelines regarding Assessment of service life.

  • 7. Bressi, S.
    et al.
    Dumont, A. G.
    Partl, Manfred N.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials. 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 material2016In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 49, no 12, p. 4975-4990Article in journal (Refereed)
    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.

  • 8. Bueno, M.
    et al.
    Hugener, M.
    Partl, Manfred
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Fracture toughness evaluation of bituminous binders at low temperatures2015In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 48, no 9, p. 3049-3058Article in journal (Refereed)
    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.

  • 9.
    Chen, Feng
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Elaguine, Denis
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Partl, Manfred N.
    EMPA, Uberlandstr 129, CH-8600 Dubendorf, Switzerland..
    Vibration-induced aggregate segregation in asphalt mixtures2020In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 53, no 2, article id 27Article in journal (Refereed)
    Abstract [en]

    Aggregate segregation in asphalt mixture is a bothersome engineering issue during pavement construction. The practitioners have some measures to mitigate the segregation potential based on experiences which, however, can only reduce the risk to a certain extent. In this research, the authors aim to contribute to the discussion in a rational non-empirical way, by using novel experimental and numerical techniques. A case study is carried out to investigate the vibration-induced segregation in asphalt mixtures, corresponding to the circumstance arising during material transportation to the construction site. A novel experimental test is conducted for evaluating the segregation characteristics of asphalt mixtures under vertical vibration in laboratory conditions. A numerical investigation based on discrete element method is further performed to study the phenomenon from a micromechanical point of view. The obtained experimental and numerical results indicate that vibratory loading induces aggregate size segregation in asphalt mixtures, and the degree of segregation is influenced profoundly by the adhesive properties of bituminous binders and the aggregate gradation.

  • 10.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Architectural Technologies.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    On the Oxidative Ageing Mechanism and Its Effect on Asphalt Mixtures Morphology2015In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 48, no 15, p. 3113-3127Article in journal (Refereed)
    Abstract [en]

    This paper investigates the influence of mixture morphologies and microstructures on oxidative ageing of asphalt mixtures. For this, an oxidative ageing mechanism based on a diffusion–reaction process was developed. Previously, most asphalt oxidative ageing modeling research focused on unidirectional diffusion of continuous oxygen flow through bitumen films, which is far from the actual boundary conditions in asphalt mixtures. For this reason in the current study, a finite element (FE) analysis has been conducted in which 3D mixture morphology was considered. Mixture morphology is the combination of mineral aggregate packing, porosity, air-void distribution and their interconnectivity. One dense and one open graded field asphalt mixture core were scanned with a computerized tomography X-ray scanner. In the analyses, the developed oxidative ageing model was implemented. The FE analysis showed that the effect of the air-void distribution, their interconnectivity and the mineral aggregate packing has a significant effect on the resulting age hardening of the overall mixture. Furthermore, from the microstructural investigation done in this research, strong indications were found that, depending on the bitumen and its conditioning, water soluble thin films are formed due to ageing. This means that ageing and moisture damage are strongly interlinked and this should thus be considered in the design of the asphaltic materials and the prediction of their long term performance.

  • 11.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Jelagin, Denis
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Investigation of the asphalt mixture morphology influence on its ageing susceptibility2015In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 48, no 4, p. 987-1000Article in journal (Refereed)
    Abstract [en]

    The main objective of this study is to investigate the influence that asphalt mixture morphology aspects have on its overall ageing behavior. Since mixture morphology is controllable, having insight into how the various morphological parameters influence the mixture’s long-term behavior can be of great value to optimize its design, regardless of the individual material properties. To do so, this study is utilizing a new framework to characterize the combined effect of aggregate packing, average air void size, porosity and level of compaction on ageing for a large set of data from different sources of field compacted and laboratory produced asphalt mixtures. The paper also hypothesizes about the mechanisms that lay behind the found influences and how thus mixture design improvements can be made. From all the investigated cases, it was found that the framework can be used to optimize the durability performance of asphalt mixtures. It was also observed that prediction of ageing behavior without considering the influence of mixture morphology may lead to erroneous conclusions and non-optimal mix design.

  • 12. Di Benedetto, H
    et al.
    de la Roche, C
    Baaj, H.
    Pronk, A.
    Lundström, Robert
    KTH, Superseded Departments (pre-2005), Civil and Architectural Engineering.
    Fatigue of bituminous mixtures2004In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 37, no 267, p. 202-216Article in journal (Refereed)
    Abstract [en]

    This paper presents an interlaboratory test campaign organized by the RILEM 182-PEB Technical Committee. In the campaign, 11 different test methods, comprising uniaxial tension/compression, 2-, 3- and 4-point bending and indirect-tension tests, were utilized in order to investigate fatigue characteristics of a dense graded asphalt concrete mixture. The testing conditions specified were sinusoidal excitation at 10Hz and 10degreesC using controlled strain and stress modes. In total, more than 150 fatigue tests were carried out during the investigation. The fatigue test results were analyzed using both classical as well as continuum damage mechanics approaches. The fatigue test results obtained using the classical fatigue approach are considerably influenced by test type and mode of loading (controlled stress or strain) used. Consequently, this approach has limited use in realistic fatigue characterization of bituminous materials and pavement structures. In contrast to the classical approach, models founded on continuum damage theory may serve to isolate intrinsic fatigue characteristics from the influence of so-called biased effects, which are largely caused by the accelerated laboratory testing. The continuum damage models investigated may constitute steps, towards a rational mechanistic fatigue characterization model, which are important for effective future pavement design.

  • 13.
    Edwards, Ylva
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering.
    Tasdemir, Yuksel
    Butt, Ali Azhar
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering.
    Energy saving and environmental friendly wax concept for polymer modified mastic asphalt2010In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 43, p. 123-131Article in journal (Refereed)
    Abstract [en]

    This paper focuses on the addition of commercial wax as flow improver in polymer modified bitumen intended for use in mastic asphalt pavements under Nordic climatic conditions. Different aspects are dealt with. The aim of the project is to make mastic asphalt used in Sweden today (for bridges, parking decks etc.) more environment friendly and easier to handle. However, wax modification must not have any noticeable negative impact on the performance of mastic asphalt at medium and lower temperatures. The project involves laboratory testing of wax and polymer modified binder mixtures as well as mastic asphalt mixtures. Effects of adding two commercial waxes to one polymer modified bitumen have been studied. The results show that both waxes have a flow improving/viscosity depressant impact on the polymer modified bitumen at higher temperatures, indicating a possible lower laying temperature for the mastic asphalt if modified with such waxes. Moreover, there is a stiffening effect at medium and high temperatures (below placing temperature), indicating a certain positive effect on stability. Concerning low temperature performance, there are results indicating some negative impact on crack susceptibility at low temperatures, more by the addition of one of the waxes than by addition of the other. However, it could be concluded that using up to at least 4% of either wax additive will improve workability for the mastic asphalt product under investigation making it possible to lower working temperatures without seriously affecting its good performance in any negative way.

  • 14.
    Edwards, Ylva
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering.
    Tasdemir, Yuksel
    Yozgat Faculty of Engineering and Architecture, Erciyes University, Yozgat, Turkey.
    Isacsson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering.
    Influence of commercial waxes and polyphosphoric acid on bitumen and asphalt concrete performance at low and medium temperatures2006In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 39, no 7, p. 725-737Article in journal (Refereed)
    Abstract [en]

    The influence of adding four types of commercial wax and one polyphosphoric acid to a non-waxy bitumen was investigated with regard to binder and asphalt concrete mixture performance. Binder properties were determined using dynamic shear rheometer (DSR), bending beam rheometer, force ductilometer and various conventional test methods. Asphalt concrete performance was investigated using tensile stress restrained specimen test (TSRST), creep test at -25 degrees C, dynamic creep test at 40 degrees C and complex modulus test at 0, 10 and 20 degrees C. Totally eleven binders and eight asphalt mixtures were investigated.

    TSRST fracture temperatures of the asphalt mixtures were marginally influenced by the addition of any of the additives, and significant physical hardening of the binders, observed by BBR testing, could not be established using TSRST. Also in creep testing of asphalt mixtures at -25 degrees C, recorded effects were less pronounced compared to binder testing.

    In dynamic creep testing, the smallest permanent strains were recorded for the asphalt mixtures containing FT-paraffin or montan wax, indicating better resistance to rutting. Adding polyethylene wax or polyphosphoric acid to the non-waxy bitumen used, showed considerable positive stiffening effects on the binder at medium and higher temperatures. However, this increase in stiffness could not be shown in dynamic creep testing (at 40 degrees C) of asphalt concrete mixtures containing these additives.

  • 15.
    Ekblad, Jonas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Statistical evaluation of resilient models for characterizing coarse granular materials2008In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 41, no 3, p. 509-525Article in journal (Refereed)
    Abstract [en]

    Consistent material modeling is a prerequisite for a mechanistic approach to pavement design. The scope of this investigation was to statistically evaluate the efficiency of various resilient models commonly encountered in highway engineering. These models were categorized as describing either resilient modulus or shear and volumetric strains. Triaxial tests using constant and cyclic confining pressure were performed on coarse granular materials of various gradings (maximum particle size 90 mm). Two statistical methods, the extra sum of squares F-test and the Akaike information criterion, were used for model comparison. Concerning resilient modulus, the Uzan model provided, in general, a statistically significant improvement compared to the k-theta model. However, this improvement is lost if a constant Poisson ratio is used to predict shear and volumetric strains. In case of the shear-volumetric approach, no single model was most likely to be the best model for all gradings studied.

  • 16. Ekblad, Jonas
    et al.
    Edwards, Ylva
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Precision of method for determining resistance of bituminous mixtures to de-icing fluids2008In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 41, no 9, p. 1551-1562Article in journal (Refereed)
    Abstract [en]

    This paper presents the results of a Round-Robin test to estimate the precision of European method EN-12697-41 "Test methods for hot mix asphalt-Resistance to de-icing fluids". The purpose of the project was to determine precision data according to ISO 5725, ASTM E691 and ASTM C802. The examined test method is intended for use in requirements specifications for airfield de-icing chemicals and/or as a tool for development of such products. Precision statistics, repeatability and reproducibility standard deviations, are based on observed values from six laboratories and six levels, each level comprising four samples. From a general statistical analysis, which was conducted in addition to precision determination, it could be concluded that the most damaging de-icing agents (treatments) were identified by all participating laboratories both in terms of absolute values and by ranks.

  • 17.
    Ekblad, Jonas
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Lundström, Robert
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Soft bitumen asphalt produced using RAP2017In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 50, no 1, article id 13Article in journal (Refereed)
    Abstract [en]

    Soft bitumen asphalt concrete is a common paving material in Scandinavia. The purpose of this investigation was to indicate the possibility to compensate for the stiff binder of reclaimed asphalt pavement (RAP) by using softer binders compared to the mix design. Characterization of binder mixing and diffusion were carried out using viscosity measurements and tests on asphalt concrete comprised stiffness modulus and cyclic compression testing. Acquired results suggest that virgin and reclaimed binders mix and the viscosity can be predicted using simple mixing models. In the case of asphalt made from mixing virgin and recycled material, the mechanical properties indicates fully mixed binders and mixing occurs during sample manufacturing. In general, this study suggests that soft asphalt mixtures can be produced using RAP and that nominal binder viscosity of the final product can be obtained by compensating the stiff binder of the RAP by virgin bitumen of a softer grade.

  • 18.
    Fadil, Hassan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Elaguine, Denis
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Partl, Manfred
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Spherical indentation test for quasi-non-destructive characterisation of asphalt concrete2022In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 55, no 3, article id 102Article in journal (Refereed)
    Abstract [en]

    The indentation test is a promising technique for the viscoelastic characterisation of asphalt concrete (AC). Indentation measurements are primarily influenced by the material properties in the direct vicinity of the indenter-specimen contact point. Accordingly, it may become a useful alternative for the characterisation of thin asphalt layers as well as for a quasi-non-destructive AC characterisation in the field. In this study, the spherical indentation test is used to measure the linear viscoelastic properties of AC mixtures extracted from a road test section. The measured complex moduli are compared to those obtained by the shear box test and are found to exhibit a linear correlation. The measurements are further analysed using the Gaussian mixture model to assign each indentation test to either aggregate-dominated or mastic-dominated response. The measurements attributed to mastic-dominated response are found to be more sensitive to the temperature and AC's binder properties as compared to the average measurements. Accordingly, the proposed test method may provide a promising tool to measure AC viscoelastic properties and monitor the changes in AC binder phase in a non-destructive manner. A finite element micromechanical model is used to identify a representative scale for the response measured in mastic-dominated tests as well as to quantify the effect of measured properties on the AC damage propensity.

  • 19.
    Fadil, Hassan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Jelagin, Denis
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Partl, Manfred
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    A spherical indentation test for quasi-non-destructive characterisation of asphalt concreteIn: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873Article in journal (Refereed)
    Abstract [en]

    The indentation test is a promising technique for the viscoelastic characterisation of asphalt concrete (AC). Indentation measurements are primarily influenced by the material properties in the direct vicinity of the indenter-specimen contact point. Accordingly, it may become a useful alternative for the characterisation of thin asphalt layers as well as for a quasi-non-destructive AC characterisation in the field. In this study, the spherical indentation test is used to measure the linear viscoelastic properties of AC mixtures extracted from a road test section. The measured complex moduli are compared to those obtained by the shear box test and are found to exhibit a linear correlation. The measurements are further analysed using the Gaussian mixture model to assign each indentation test to either aggregate-dominated or mastic-dominated response. The measurements attributed to mastic-dominated response are found to be more sensitive to the temperature and AC’s binder properties as compared to the average measurements. Accordingly, the proposed test method may provide a promising tool to measure AC viscoelastic properties and monitor the changes in AC binder phase in a non-destructive manner. A finite element micromechanical model is used to identify a representative scale for the response measured in mastic-dominated tests as well as to quantify the effect of measured properties on the AC damage propensity.

  • 20. Fang, Xing
    et al.
    Garcia, Alvaro
    Winnefeld, Frank
    Partl, Manfred N.
    KTH, School of Architecture and the Built Environment (ABE).
    Lura, Pietro
    Impact of rapid-hardening cements on mechanical properties of cement bitumen emulsion asphalt2016In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 49, no 1-2, p. 487-498Article in journal (Refereed)
    Abstract [en]

    Cement bitumen emulsion asphalt (CBEA) is obtained by mixing bitumen emulsion, cement, aggregates and filler at ambient temperature. CBEA is thought to be a promising substitute for hot mix asphalt because of its low environmental impact and cost-effectiveness. Disadvantages of this material are the long time required to reach its full strength and the inadequate understanding of the hardening mechanisms. This study aims at accelerating the development of mechanical properties of CBEA by using rapid-hardening cements while at the same time gaining a deeper understanding of the role of cement in CBEA. With this purpose, cold mix asphalt mixtures with cationic and anionic emulsions and different types of cement (ordinary Portland, calcium sulfoaluminate and calcium aluminate cement) were studied by means of isothermal calorimetry, measurements of water evaporation and Marshall tests. The results indicate that both anionic and cationic bitumen emulsions may affect the initial hydration rates of the cements used but have no significant influence on their degree of hydration after a few days. The addition of calcium sulfoaluminate and calcium aluminate cement to CBEA leads to mechanical properties after 1-day curing similar to those obtained with Portland cement after 1-week curing. Cement hydration dominates the strength gain, especially for rapid-hardening cements, and the type of cement influences both the amount of bound water and the rate of water evaporation from the CBEA.

  • 21. Garcia, Alvaro
    et al.
    Lura, Pietro
    Partl, Manfred N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Jerjen, Iwan
    Influence of cement content and environmental humidity on asphalt emulsion and cement composites performance2013In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 46, no 8, p. 1275-1289Article in journal (Refereed)
    Abstract [en]

    Asphalt and cement concrete are the most popular materials used in the construction of roads, highways, bridge deck surface layers and pavements in airports and other areas with heavy wheel roads. Whereas asphalt possesses, compared to concrete, the advantages of a short curing period, high skid resistance and easy maintenance, it also shows lower fatigue durability, ravelling and rutting due to repeated concentrated loads and susceptibility to temperature changes and moisture. On the other hand, concrete pavements are initially more expensive, have lower driving comfort and are susceptible to cracking due to volume changes and to salt damage. A material with low-environmental impact and with advantages of both asphalt and concrete may be obtained by combining bitumen emulsions and a cementitious material. In this paper, cold asphalt mixtures with different amounts of cement were tested with Marshall stability tests. Selected mixtures were also cured at different environmental relative humidity (35, 70 and 90 % RH). By monitoring the mass of the specimens and estimating the water bound by the cement, the total water remaining in the mixtures was calculated. Details of the microstructure in the mixtures were examined with X-ray microtomography. According to the results of the present study, cement contributes to the hardening of cold asphalt mixtures both by creating cement paste bridges between the aggregates and by removing water from the mixtures through cement hydration. Asphalt and cement composites appear to be promising materials for implementation in real pavements, although their rate of hardening needs to be improved further.

  • 22. Garcia, Alvaro
    et al.
    Norambuena-Contreras, J.
    Partl, Manfred N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering. Empa Swiss Federal Laboratories for Materials Science and Technology, Switzerland.
    A parametric study on the influence of steel wool fibers in dense asphalt concrete2014In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 47, no 9, p. 1559-1571Article in journal (Refereed)
    Abstract [en]

    Environmental conditions combined with traffic loads contribute to premature deterioration of asphalt concrete pavements, reducing their strength and durability over time. To improve it, fibers can be incorporated in the mixture. Additionally, electrically conductive fibers can be used for self-healing purposes. In this context, this paper evaluates the influence of flexible steel fibers (steel wool) on the mechanical and physical properties of dense asphalt concrete. With these purposes, 25 different mixtures, with the same aggregate gradation and amount of bitumen, but with two different fibers lengths, four different percentages, and four different diameters of steel wool have been considered. Additionally, the influence of fibers on test specimens with three different types of damage: water damage, salt water damage and ageing have been evaluated through particle loss tests. Moreover, the influence of different temperatures on the flexural strength of dense asphalt concrete with steel wool fibers has been studied. It was found that steel wool fibers do not significantly improve the mechanical properties and damage resistance of dense asphalt concrete. On the other hand, steel wool fibers can change the air void distribution of a mixture, and therefore even reduce its particle loss resistance. As a recommendation, it is indicated that, for induction heating purposes, short fibers, with big diameters should be used, since they do not seem to alter the original properties of dense asphalt concrete.

  • 23.
    Gasch, Tobias
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Malm, Richard
    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.
    Three-dimensional simulations of ageing concrete structures using a multiphase model formulation2019In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 52, no 4, article id 85Article in journal (Refereed)
    Abstract [en]

    The durability of concrete structures is in no small degree determined by the quality and integrity of the concrete, where structural damages such as cracks negatively affect many of the functions of the structure. Often cracks are formed due to restrained thermal and hygral deformations, where the risk is exceptionally high during the early stages after casting. This study presents a hygro-thermo-chemo-mechanical model that accounts for phenomena such as hydration, external and internal drying, self-heating, creep, shrinkage and fracture. The model is derived as a modified version of a fully-coupled multiphase model recently proposed by Gasch et al. (Cem Concrete Res 116:202–216, 2019. https://doi.org/10.1016/j.cemconres.2018.09.009) and implemented in the Finite Element Method. Here the governing equations are simplified, and a more efficient solution method is proposed. These modifications are made with the intention to obtain a model more suitable for structural scale simulations. To validate the model, one of the end-restrained beams tested within the French research project CEOS.fr is analyzed. Laboratory data on the concrete is used to calibrate to model and recordings of ambient conditions makes it possible to define accurate boundary conditions. Results from the simulation are compared to measured temperatures and deformations from the first 60 days after casting and are found to generally be in good agreement. Compared to the fully-coupled model by Gasch et al. (2019), the modifications proposed in this study reduce the computational cost by a factor five; without any noticeable differences to the structural results.

  • 24.
    Ghafoori Roozbahany, Ehsan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Partl, Manfred
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    A new test to study the flow of mixtures at early stages of compaction2016In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 49, no 9, p. 3547-3558Article in journal (Refereed)
    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.

  • 25.
    Gram, Annika
    et al.
    Swedish Cement and Concrete Research Institute.
    Silfwerbrand, Johan
    Swedish Cement and Concrete Research Institute.
    Numerical Simulation of Fresh SCC Flow: Applications2011In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 44, no 4, p. 805-813Article in journal (Refereed)
    Abstract [en]

    Numerical simulation of self-compacting concrete (SCC) flow shows great potential for developing into a powerful tool for prediction of SCC form filling. Numerical simulation is also of interest for modelling small scale material phenomena. This paper presents three different applications useful for modelling different phenomena on different scales: (i) particles, each representing an aggregate in the concrete, (ii) fluid, modelling concrete as a homogeneous liquid and (iii) particle in fluid, studying details of flow. The methods are compared and evaluated in order to give the reader a quick guidance into the world of possibilities that open up with numerical simulation.

  • 26.
    Gudmarsson, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Rydén, Nils
    Lund Univ, Sweden.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Application of resonant acoustic spectroscopy to asphalt concrete beams for determination of the dynamic modulus2012In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 45, no 12, p. 1903-1913Article in journal (Refereed)
    Abstract [en]

    In this paper, a new application of resonant acoustic spectroscopy (RAS) is examined for constructing asphalt concrete mastercurves from seismic testing. The frequency-dependent material properties can be characterized from multiple modes of vibration through the use of RAS. Beam-shaped asphalt specimens are tested at multiple temperatures to determine the resonance frequencies of the specimens. The resonance frequencies are estimated by applying a small load impulse and measuring the resulting acceleration through the specimens. Using RAS, the material properties of the specimens are determined numerically using the measured resonance frequencies. The results presented show that the frequency-dependent dynamic modulus of the asphalt concrete specimens can be characterized using several modes of vibration at each testing temperature.

  • 27.
    Hailesilassie, Biruk W.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Hean, Sivotha
    Partl, Manfred N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering. Swiss Federal Laboratories for Material Science and Technology (EMPA), Switzerland.
    Testing of blister propagation and peeling of orthotropic bituminous waterproofing membranes2015In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 48, no 4, p. 1095-1108Article in journal (Refereed)
    Abstract [en]

    Bridge decks are commonly subjected to harsh environmental conditions that often lead to serious corrosion problems, which are triggered by blisters under the hot mix asphalt bridge deck pavement with waterproofing membranes. These blisters are secretly evolving during weather exposure until often being detected too late. Formation of blisters under the waterproofing membrane is caused by a complex mechanism governed by bottom-up pressure and loss of adhesion. This paper primarily intends to adopt the analytical blister propagation energy approach for waterproofing membranes and compare it with adhesive fracture energy from standard peeling test methods, already described in the literature. Three different types of polymer modified bitumen membranes (PBM) were used for this purpose. The investigation includes a comparison between uniaxial and biaxial testing conditions for determining the modulus of elasticity of the membranes. Moreover, the influence of the displacement rate and temperature on the adhesive fracture energy in peeling tests is investigated. It was found that the biaxial modulus of PBM in the longitudinal and transversal direction is comparable with the uniaxial tension testing results in the main directions. In addition, it was observed that the ratio of longitudinal and transversal modulus of elasticity was similar. The energy calculated from tests with elliptical blister propagation showed a comparable value to the standard peeling fracture energy for similar types of PBM.

  • 28.
    Hailesilassie, Biruk Wobeshet
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Hugener, M.
    Bieder, A.
    Partl, Manfred N.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials. EMPA, Swiss Federal Laboratories for Material Science and Technology, Switzerland.
    New experimental methods for characterizing formation and decay of foam bitumen2015In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873Article in journal (Refereed)
    Abstract [en]

    Formation and decay of foam bitumen is a highly dynamic temperature dependent process which makes characterization difficult. In this research, new experimental tools were applied for characterizing the bitumen foam during the foaming process. Ultrasonic sensors were used for accurately monitoring the expansion and decay of foam bitumen as a function of time. Assessment of foam bitumen viscosity was performed using high frequency torsional rheometer and in situ observation by X-ray radiography. A high-speed camera was applied for examining the foam bitumen stream right at the nozzle revealing that foam bitumen at a very early stage contains fragmented pieces of irregular size rather resembling a liquid than foam. Moreover, infrared thermal images were taken for obtaining information on the in situ surface temperature of foam bitumen during the hot foaming process. The result showed that the average surface temperature of foam bitumen depends on the water content of the bitumen and bubble size distribution, 108 and 126 °C for 4 and 1 wt% (by weight) water content respectively. The residual water content in the decaying foam bitumen was determined by thermogravimetric analysis. The result demonstrated that residual water content depends on the initial water content, and was found to be between 38 and 48 wt% of the initial water content of 4–6 wt%. Finally, X-ray computed tomography was applied for examining the decay of foam bitumen revealing that the bubbles of foam bitumen remain trapped close to the surface of the foam bitumen.

  • 29.
    Hallberg, Daniel
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Development of the Swedish bridge management system by introducing a LMS concept2005In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 40, no 6, p. 627-639Article in journal (Refereed)
    Abstract [en]

    The Swedish Road Administration (SRA) has developed an information technology (IT) based bridge and tunnel management system (BaTMan) that is widely implemented by the organisation. The system is a tool for operational, tactical and strategic management. However, this system does not include systems and tools for managing optimisation and long-term planning of␣Maintenance, Repair and Rehabilitation (MR&R) actions due to service life performance aspects. This paper discusses the need of service life performance analysis for sound optimisation and long-term planning of MR&R actions in the bridge management. The paper presents a service life performance analysis model that is based on a Markov chain model and the MEDIC method. The model is developed to manage different kinds of degradation characteristic and yet present a uniform result expressed in conditional probabilities. The paper discusses also the need of systems and tools for describing objects on both an overall level and on a component level.

  • 30.
    Hallgren, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Kjellsen, Knut O.
    Norcem.
    Wallevik, Olafur H.
    Icelandic Building Research Institute.
    Fracture mechanical properties of high-performance concrete - Influence of silica fume2000In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 33, no nov, p. 552-558Article in journal (Refereed)
    Abstract [en]

    High-performance concrete and high-quality ordinary concrete, with or without silica fume, were tested for mechanical and fracture mechanical properties. Testing was performed at 28 days and 2 years. Ten percent silica fume resulted in a 20 to 25% increase in the direct tensile strength and a 10 to 20% increase in flexural and compressive strength, but had little effect on the dynamic modulus of elasticity. The brittleness appeared to increase with the presence of silica fume.

  • 31.
    Hallgren, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Kjellsen, Knut O.
    Norcem.
    Wallevik, Olafur H.
    Icelandic Building Research Institute.
    On the Compressive Strength Development of High-Performance Concrete and Paste – Effect of Silica Fume1999In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 32, no jan-feb, p. 63-69Article in journal (Refereed)
    Abstract [en]

    The compressive strength development of sealed high-performance concrete and paste specimens, with and without silica fume, have been studied from 1 day and up to 4 years. The paste and concrete specimens were prepared in such a way that segregation was avoided and the silica fume became well dispersed. Under these conditions silica fume increased the strength of paste just as much as it increased the strength of concrete. It appears that the enhancing effect of silica fume on concrete strength is due to an improved strength of the paste phase as a whole, and not due to an improved bond strength between the paste phase and the aggregate particles, as has been suggested earlier. The concretes and the pastes with 10% silica fume appeared to loose strength over a period of time before the strength increased again.

  • 32.
    Hedebratt, Jerry
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Silfwerbrand, Johan L.
    Swedish Cement & Concrete Res Inst, Stockholm, Sweden.
    Full-scale test of a pile supported steel fibre concrete slab2014In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 47, no 4, p. 647-666Article in journal (Refereed)
    Abstract [en]

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

  • 33.
    Hesami, Ebrahim
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Numerical and experimental evaluation of the influence of the filler-bitumen interface in mastics2014In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 47, no 8, p. 1325-1337Article in journal (Refereed)
    Abstract [en]

    The successful use of additives in modified asphalt mixtures, such as warm mix asphalt, depends largely on the effect such modification has on the mastic. Previous research indicated that such modifiers do not simply change the bitumen properties, but can also change the interaction between the filler and the bitumen matrix. Understanding the effect of the properties of the fillers, the bitumen and their interaction is thus important for future asphalt mix design. In order to investigate this and to define the dominant relationships, this paper combines a numerical and experimental approach. In the experiments, the viscosities of modified and unmodified mastics with different filler concentrations and types were systematically investigated utilizing a novel testing protocol. In the numerical analyses, the Finite Element Method was utilized for a micro-mechanical analysis, in which the shape and size of the filler particles were varied in the bitumen matrix. Combining the experimental and numerical results allowed for a detailed investigation of the effect of the interface properties, with and without modifiers. The research further indicated that the effect of the shape and size of the fillers varied, depending on the interface properties. From the research relationships were established between the overall mastic viscosity and the influence of the filler-bitumen interface, considering shape and size. The conclusion of this paper can thus be useful for the effective development of modified asphalt mixtures and gives strong indications towards future research directions.

  • 34.
    Inozemtcev, Sergey
    et al.
    Natl Res Moscow State Univ Civil Engn, Dept Bldg Mat Sci, Moscow, Russia..
    Jelagin, Denis
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Korolev, Evgeniy
    Natl Res Moscow State Univ Civil Engn, Res & Educ Ctr Nanomat & Nanotechnol, Moscow, Russia..
    Fadil, Hassan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Partl, Manfred
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Trong, Toan Do
    Experimental and numerical study on SMA modified with an encapsulated polymeric healing agent2022In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 55, no 9, article id 230Article in journal (Refereed)
    Abstract [en]

    The present study aims at experimentally and numerically investigating the effect an encapsulated healing agent on the mechanical characteristics of a stone mastic asphalt (SMA). As a healing agent a thiol-containing urethane AR-polymer is used in this study. In order to gain a numerical insight into mechanical behavior of the capsules in SMA, a micromechanical finite element modeling is employed. The developed model allows capturing the stresses induced in the capsules at different load cases applied to the SMA on macro-scale. Particular attention is paid presently to the numerical evaluation of the local stress state that arises around capsules during compaction, operation, and also during crack initiation. SMA mixtures with various volumetric contents of healing capsules were manufactured and the capsules survival during mixture production was evaluated based on X-Ray Computed Tomography measurements. The effect of capsules on the self-healing properties of asphalt mixtures has furthermore been examined with repeated compressive strength tests. The obtained experimental results indicate that the absolute majority of capsules survive mixture production, and that their addition increases the SMA strength recovery during the healing period. The experimental and numerical results concerning capsules breakage are found to be in reasonable agreement. The developed micromechanical model may thus potentially provide a useful tool for optimization of capsules mechanical properties in order to improve their survival during mixture production as well as their timely activation.

  • 35.
    Jansson, Robert
    et al.
    Swedish Technical Research Institute.
    Boström, Lars
    Swedish Technical Research Institute.
    Factors influencing fire spalling of self compacting concrete2013In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 46, no 10, p. 1683-1694Article in journal (Refereed)
    Abstract [en]

    The influence of age on the fire spalling behaviour of high performance concrete is not known in detail. The present study shows that in three out of four mixes of self compacting concretes tested, the fire spalling tendency decreases at higher age whereas for the fourth mix the spalling did not decrease. The fourth mix, with the highest limestone content, spalled more after 4 years storage than the other mixes despite the fact that the moisture content was in the same region as the other mixes tested. Important findings are also that an addition of polypropylene fibres could expunge the spalling behaviour and that the specimen size and application of compressive load on the test specimens used in this type of studies influence the spalling behaviour strongly.

  • 36.
    Jena, Naresh K.
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Lyne, ÅL.
    Natarajan Arul, Murugan
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Birgisson, B.
    Atomic level simulations of the interaction of asphaltene with quartz surfaces: role of chemical modifications and aqueous environment2017In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 50, no 1, article id 99Article in journal (Refereed)
    Abstract [en]

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

  • 37.
    Johansson, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Janz, Mårten
    Silfwerbrand, Johan
    Trägårdh, J.
    Moisture fixation in concrete treated with a water repellent agentIn: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873Article in journal (Other academic)
  • 38.
    Karlsson, S.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, A-C.
    The biodegradation of a biopolymeric additive in building materials1990In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 23, no 137, p. 352-357Article in journal (Refereed)
  • 39.
    Karlsson, S.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Banhidi, Z.G.
    Albertsson, A-C.
    Gas chromatographic detection of volatile amines found in indoor air due to putrefactive degradation of casein-containing building materials1989In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 22, no 3, p. 163-169Article in journal (Refereed)
  • 40.
    Khavassefat, Parisa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Jelagin, Denis
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    A computational framework for viscoelastic analysis of flexible pavements under moving loads2012In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 45, no 11, p. 1655-1671Article in journal (Refereed)
    Abstract [en]

    A general quasi-static computational procedure is established to evaluate stresses and strainsinduced in the viscoelastic flexible pavement bymoving traffic. The procedure is based on superposition principle and is computationally favourable, as itrequires only reduced incremental problem to besolved numerically. The impact of traffic speed anddensity on the mechanical response of flexible pavement is examined numerically. Results relevant fortwo major modes of pavement’s distress, i.e. crackingand rutting, are reported. It is shown that the state-ofpractice layered elastic analysis used in pavementdesign is unable to capture several important qualitative and quantitative aspects of pavements response.

  • 41.
    Laurell Lyne, Åsa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Krivosheeva, Olga
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Adhesion between bitumen and aggregate: implementation of spectroscopic ellipsometry characterisation and estimation of Hamaker's constant2013In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 46, no 10, p. 1737-1745Article in journal (Refereed)
    Abstract [en]

    Refractive indices of seven bitumen samples and three aggregates (typical components in flexible asphalt pavement) were determined by ellipsometry in order to predict bitumen-aggregate adhesion and bitumen-bitumen cohesion using Hamaker’s constant.

    Hamaker’s constant according to Lifshitz was introduced to the asphalt field by two of the authors to describe and estimate van der Waal’s interaction and bitumen–aggregate adhesion. Lifshitz used the refractive index to estimate the dispersive non-polar van der Waal’s interaction component of adhesion, the predominant component in adhesion between minerals and bituminous binder. The impact of an intervening thin medium such as air or water on the adhesion can be estimated using Hamaker’s coefficient, which in turn can be related to stripping potential.

    The bitumen binders studied were delivered as a paving grade 70/100 according to EN 12591:2009 and came from different bitumen suppliers. The three aggregates studied were two types of granite and one diabase.

    It is concluded from the measurement of refractive indices and calculations of the Hamaker’s constant that there was a larger spread in refractive index among the three aggregate samples studied than among the seven bitumen samples.

  • 42.
    Laurell Lyne, Åsa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Redelius, Per
    Nynas AB, Stockholm, Sweden.
    Collin, Måns
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Characterization of stripping properties of stone material in asphalt2013In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 46, no 1-2, p. 47-61Article in journal (Refereed)
    Abstract [en]

    Aggregates and bitumen together form a composite called asphalt concrete pavement. Moisture damage to asphalt concrete pavement can occur as stripping, and is a common problem that can lead to costly repairs. There is therefore a need to understand which stone aggregates adhere best to bituminous binder and result in a minimum of stripping. Lifshitz used the refractive index to estimate the dispersive non-polar van der Waal's interaction component of adhesion, the predominant component in adhesion between minerals and bituminous binder. The impact of an intervening thin medium such as air or water on the adhesion can be estimated using Hamaker's coefficient, which in turn can be related to stripping potential. Aggregates consist of minerals and minerals consist of different elements. The objective of this study was to investigate variation in the dispersive component of minerals via their refractive indices using data from mineral data sheets. The influence of the position of elements in the periodic table and chemical composition on refractive index of minerals was examined in order to classify mineral aggregates for asphalt road building with regard to dispersive adhesive properties and expected resistance to stripping. It is clear from this study that the elemental composition of a mineral will affect its refractive index and hence its dispersive adhesion to bitumen. Aggregates and minerals have been classified according to degree of stripping in the literature. In this study it was shown that aggregates and minerals that have a refractive index higher than approximately 1.6 are expected to be less susceptible to stripping. Also, minerals containing alkali metals are sensitive to stripping since they are partially soluble in water.

  • 43.
    Laurell Lyne, Åsa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering.
    Redelius, Per
    Nynas Bitumen, Nynäs AB, Nynäshamn, Sweden.
    Collin, Måns
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering.
    The mechanism of adhesion between aggregates and bitumen in asphaltIn: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873Article in journal (Refereed)
  • 44.
    Lira, Bernardita
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Jelagin, Denis
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Gradation-based framework for asphalt mixture2013In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 46, no 8, p. 1401-1414Article in journal (Refereed)
    Abstract [en]

    Aggregates are the major component of asphalt mixtures, greatly influencing the mixtures resistance to failure. The structure that is formed by the aggregates will depend mostly on the size distribution, shape and mineral composition. Coarse aggregate have a strong influence on the resistance to rutting, while fines provide stability to the mixture. In the present study a generalized framework is developed to identify the range of aggregate sizes which form the load carrying structure in hot mix asphalt and determine its quality. The method has been developed as a numerical procedure based on packing theory. Parameters like porosity and coordination number have been used to evaluate the quality of the load carrying structure and relate it to resistance to rutting. The framework has been evaluated on several field and laboratory mixtures and related to their rutting performance. The gradation analysis of the mixtures has compared favorably with the performances reported from the field and laboratory testing. The developed gradation analysis framework has proven to be a tool to identify those mixtures with a poor rutting performance based on the gradation of the aggregates.

  • 45. Lyne, Asa Laurell
    et al.
    Taylor, Nathaniel
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Jaeverberg, Nadja
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Edin, Hans
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Birgisson, Bjorn
    Low frequency dielectric spectroscopy of bitumen binders as an indicator of adhesion potential to quartz aggregates using Portland cement2016In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 49, no 4, p. 1327-1336Article in journal (Refereed)
    Abstract [en]

    The purpose of this investigation was to interpret the bitumen-aggregate adhesion based on the dielectric spectroscopic response of individual material components utilizing their dielectric constants, refractive indices and average tangent of the dielectric loss angle (average loss tangent). Dielectric spectroscopy of bitumen binders at room temperature was performed in the frequency range of 0.01-1000 Hz. Dielectric spectroscopy is an experimental method for characterizing the dielectric permittivity of a material as a function of frequency. Adhesion data has been determined using the Rolling bottle method. The results show that the magnitude of the average tangent of the dielectric loss angle (average loss tangent) depends on bitumen type. The average loss tangent in the frequency range 0.01-1 Hz is introduced as a potential indicator for predicting polarizability and, thereby, adhesion potential of bitumen binders to quartz aggregates when using Portland cement. In order to obtain acceptable adhesion of 70/100 penetration grade bitumen binders and quartz aggregates when using Portland cement, it is suggested that the binder have an average tan delta > 0.035 in the frequency range 0.01-1 Hz.

  • 46.
    Makoundou, Christina
    et al.
    Univ Bologna, Dept Civil Chem Environm & Mat Engn, Via Terracini 28, I-40131 Bologna, Italy.;Res Inst Sweden RISE, Dept Mat & Surface Design, S-11428 Stockholm, Sweden..
    Fathollahi, Alireza
    Coventry Univ, Ctr Agroecol Water & Resilience CAWR, Wolston Lane, Coventry CV8 3LG, England.;Univ Strathclyde, Dept Civil & Environm Engn, Glasgow, Scotland..
    Kleiven, Svein
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Coupe, Stephen J.
    Coventry Univ, Ctr Agroecol Water & Resilience CAWR, Wolston Lane, Coventry CV8 3LG, England..
    Sangiorgi, Cesare
    Univ Bologna, Dept Civil Chem Environm & Mat Engn, Via Terracini 28, I-40131 Bologna, Italy..
    Mechanical and leaching characterisation of impact-absorbing rubberised asphalts for urban pavements2023In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 56, no 3, article id 55Article in journal (Refereed)
    Abstract [en]

    A new impact-absorbing material is being developed to protect vulnerable road users in urban areas and has been produced and tested, mechanically and environmentally in the laboratory. The main constituent of this innovative material is the rubber recycled from end-of-life tyres to foster a circular use of resources and exploit rubber's elastic properties. The study aims to provide a complete Uniaxial Compression Test (UCT) and leaching analysis of the material to propose and optimise a mix that is mechanically sound, durable, and respectful of the environment, in view of in-situ applications. Therefore, the UCT and Dynamic Surface Leaching Test (DSLT) were carried out on rubberised asphalt specimens with different mix designs. The 64 days cumulative concentrations of leached heavy metals and trace elements from unit surface of specimens were calculated and quantified, according to the CEN/TS 16637 standard. In parallel, thanks to a specific mechanical characterisation, compressive stress-strain curves were obtained, and the relaxation and elastic modulus were evaluated. The results from the compression tests showed that the A-mixes have the best elastic and absorbing behaviour, especially those made with an SBS-modified bituminous emulsion (A4). The results from DSLT showed that the cumulative concentration of released elements, per unit surface of specimens were lower than the Dutch Soil Quality Decree (SQD) thresholds, taken as a reference. The low and early release of leachant observed for the mixtures, especially A4 as the most promising one, leave the possibility to handle the leaching with several solutions, including rubber coating treatment or water washing before their incorporation into the mix to limit and prevent their leaching while permitting very high injury reduction performances.

  • 47.
    Marteinsson, Björn
    et al.
    Högskolan i Gävle.
    Norberg, Peter
    Temperature and moisture condition and degradation2005In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873Article in journal (Other academic)
  • 48. Moosberg-Bustnes, Helena
    et al.
    Lagerblad, Björn
    Swedish Cement & Concrete Res Inst.
    Forssberg, Erik
    The Function of Fillers in Concrete2004In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 37, no 266, p. 74-81Article in journal (Refereed)
    Abstract [en]

    The purpose of this investigation has been to evaluate the effect of quartz filler on concrete strength and microstructure, and to see if it is possible to replace cement with filler without loss of strength. Fillers are materials whose function in concrete is based mainly on size and shape. They can interact with cement in several ways; to improve particle packing and give the fresh concrete other properties, and even to reduce the amount of cement in concrete without loss of strength. Quartz was chosen as filler material, since it is inert and is available both as a by-product and a natural raw material. Different amounts of filler were used in the various experiments, as well as different particle size distributions. The results are positive: fillers can partially replace cement and at the same time improve the properties and the microstructure of the concrete. This research is part of a larger project that aims to find uses for by-products in concrete.

  • 49.
    Partl, Manfred
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials. KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering. Empa, Swiss Federal Laboratories for Materials Science and Technology Road Engineering/Sealing Components, Duebendorf, Switzerland .
    Editorial2014In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 47, no 8, p. 1271-1272Article in journal (Refereed)
  • 50.
    Partl, Manfred
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials. PaRRC Partl Rd Res Consulting, Binzstr 357, CH-5072 Oeschgen, Switzerland..
    M&S highlight: Isacsson and Lu (1995), Testing and appraisal of polymer modified road bitumens-state of the art2022In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 55, no 2, article id 32Article in journal (Other academic)
12 1 - 50 of 59
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