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  • 1. Al-Ayish, N.
    et al.
    During, O.
    Malaga, K.
    Silva, N.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    The influence of supplementary cementitious materials on climate impact of concrete bridges exposed to chlorides2018In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 188, p. 391-398Article in journal (Refereed)
    Abstract [en]

    In order to reach a specific service life of reinforced concrete structures a certain cover thickness is needed. At present, this is regulated by national standards that also limit the amount and type of supplementary cementitious materials in different exposure environments. The regulations do not, however, consider the actual durability performance of concrete with supplementary cementitious materials. As a consequence, the LCA results might be misleading. This paper shows the environmental impact of concrete with supplementary cementitious materials in chloride environment considering their specific performances. Prescriptive and performance based service life prediction models for chloride ingress are applied and compared. 

  • 2.
    Bagampadde, Umaru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering.
    Kiggundu, B. M.
    Influence of truck load channelization on stripping in asphalt mixtures2007In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 21, no 8, p. 1628-1635Article in journal (Refereed)
    Abstract [en]

    The influence of load channelization on stripping was investigated using cores and block samples from a heavily loaded highway. The original 80/100 asphalt (virgin and RTFOT aged) was characterized using conventional methods. Stripping of mixtures was measured using ASTM D1664 and that of cores using visual diametral plane rating and loss in indirect tensile strength due to soaking. The pore saturation and air voids were found to be influenced by ground water level and wheel track location across traffic lanes. Stripping was rated higher in the wheel paths than between wheel paths, especially in shallow water table areas where it was observed to be 82% higher, implying possible dependency of stripping on channelization. To enhance resistance to moisture damage, it is recommended that Hot Mix Asphalt surfaces in areas with shallow water tables be designed to a more favorable refusal density.

  • 3.
    Bekele, Abiy
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Balieu, Romain
    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.
    Rydén, Nils
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Gudmarsson, Anders
    Peab Asfalt AB, Drivhjulsvagen 11, S-12630 Hagersten, Sweden..
    Micro-mechanical modelling of low temperature-induced micro-damage initiation in asphalt concrete based on cohesive zone model2021In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 286, article id 122971Article in journal (Refereed)
    Abstract [en]

    Asphalt pavement is subjected to cyclic temperature variations during its service life owing to changes in daily and seasonal climatic conditions. These variations tend to accumulate thermally induced distress leading to initiation and evolution of micro-cracks. The effect of cyclic thermal variations as well as ther-mal incompatibility of mastic and aggregates is of major significance for understanding the behavior of thermally induced damage in pavements. Thermal stress is developed due to differential contraction of mastic relative to aggregates in asphalt concrete at low temperatures. In this paper, low temperature micro-damage initiation in asphalt concrete due to differential thermal contraction is modelled using 2D micro-mechanical volume element. Cohesive zone model (CZM) is adopted to simulate low temper-ature damage initiation at the mastic-aggregate interface (adhesive failure) within the mixtures. A cycle of cooling and heating is applied in the micro-mechanical model in order to capture the effect of thermal damage initiation on the overall stiffness modulus of the mixtures. The results from the model reveal a reduction in stiffness modulus (as compared to the values at similar temperatures within a cycle) after the temperature of-40 degrees C is reached within the applied cyclic cooling and heating. The effects of aggre-gate gradation and binder grade are also monitored by considering four cases of mixtures formed from a combination of two different gradations and two different mastics. Results of the micro-mechanical mod-elling are also compared with experimental observations of comparable mixture types.

  • 4.
    Bekele, Abiy
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Balieu, Romain
    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.
    Rydén, Nils
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Civil and Architectural Engineering Laboratory.
    Gudmarsson, Anders
    KTH, School of Architecture and the Built Environment (ABE).
    Micro-mechanical Modelling of Low temperature-induced micro-damageinitiation in asphalt concrete based on Cohesive zone model2020In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526Article in journal (Refereed)
  • 5.
    Bekele, Abiy
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Rydén, Nils
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Gudmarsson, Anders
    Peab Asfalt AB, Drivhjulsvagen 11, S-12630 Hagersten, Sweden..
    Birgisson, Björn
    Department of Civil Engineering, Texas A&M University, 3136 TAMU, College Station, 77843-3136, TX, United States.
    Effect of cyclic low temperature conditioning on stiffness modulus ofasphalt concrete based on non-contact resonance testing method2019In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 225, p. 502-509Article in journal (Refereed)
    Abstract [en]

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

  • 6.
    Bjurström, Henrik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Gudmarsson, Anders
    Ryden, Nils
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Starkhammar, Josefin
    Field and laboratory stress-wave measurements of asphalt concrete2016In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 126, p. 508-516Article in journal (Refereed)
    Abstract [en]

    Abstract Non-contact surface wave measurements are performed on a new asphalt concrete (AC) pavement using 48 micro-electro-mechanical system (MEMS) sensors as receivers to estimate the real part of the dynamic moduli of the AC top layer. Laboratory measurements of core samples, extracted from the field measurement positions, are used to construct master curves for comparison with the field measurements. The real parts of the dynamic moduli from the two test methods are consistent at the field measurement temperatures, and the non-contact field measurements are highly repeatable. These results indicate a possible application for quality assurance of AC based on mechanical properties.

  • 7.
    Björk, Folke
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Enochsson, Tomas
    Properties of thermal insulation materials during extreme environment changes2009In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 23, no 6, p. 2189-2195Article in journal (Refereed)
    Abstract [en]

    In this experimental study properties of condense formation, drainage and moisture dependent heat transmittance were studied for three different thermal insulation materials often used in railway carriages; glass wool (from Isover), melamine foam (Basotect) and corrugated sheets of cellulose plastics (Moniflex). The materials are quite different with respect to condense formation and maximal moisture accumulation at similar environmental conditions. They showed also considerable differences in moistures' influence on thermal transmissivity. The higher the moisture accumulation, the bigger the moistures' influence on thermal transmissivity at steady state. At a sudden reversion of the temperature field the moisture gave a temporary effect of even higher heat transmission for 1-2 h.

  • 8.
    Björk, Folke.
    et al.
    KTH, Superseded Departments (pre-2005), Civil and Architectural Engineering.
    Eriksson, C. A.
    Measurement of alkalinity in concrete by a simple procedure, to investigate transport of alkaline material from the concrete slab to a self-levelling screed2002In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 16, no 8, p. 535-542Article in journal (Refereed)
    Abstract [en]

    A test procedure for measurement of alkalinity for cementitious materials that is, reliable, simple. and only needs a small amount of sample, was developed and applied to check whether transport of alkaline material from a concrete surface to a covering screed can result in a detectable increase in pH-value. It was found that any transport of alkaline material from a rather humid concrete did not increase the level of alkalinity (or pH-value) of the screed covered with a carpet. It was noted that carbonation Occurred gradually from the surface and inwards when the materials were exposed to ambient air. For the prisms, of 95%, RH pH-value in the concrete surface increased with time. A transport process that allows hydroxide ions solved in the pore water in the concrete to diffuse towards the carbonated surface and thus give an increased pH-value, can explain this.

  • 9.
    Björk, Folke.
    et al.
    KTH, Superseded Departments (pre-2005), Civil and Architectural Engineering.
    Eriksson, C. A.
    Karlsson, Sigbritt
    KTH, Superseded Departments (pre-2005), Polymer Technology.
    Khabbaz, F.
    Degradation of components in flooring systems in humid and alkaline environments2003In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 17, no 3, p. 213-221Article in journal (Refereed)
    Abstract [en]

    Constituents from products that are used in the flooring on a concrete slab such as carpets of plasticised PVC and water-based adhesives sometimes degrade in an alkaline and humid environment. The concrete itself could be such an environment. In order to examine the effect of different levels of alkalinity and humidity on the mentioned products a specialised procedure was developed. By this procedure it was possible to imitate the effect of an environment of alkalinity and humidity corresponding to a recently produced concrete slab on different substances and also collect volatile degradation products produced. Degradation of some of the constituents was dependent on the levels of alkalinity and humidity, although there were significant differences in the possibility to resist the environmental factors. For some of the components, an increase in alkalinity resulted in a much higher production of degradation products even when the relative humidity was kept on a comparatively low level. The results give basis for a recommendation not to adhere plastic floorings directly to a recently produced slab of high-quality concrete because the alkaline material in the concrete could cause degradation.

  • 10. Bueno, M.
    et al.
    Hugener, M.
    Partl, Manfred Norbert
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Low temperature characterization of bituminous binders with a new cyclic shear cooling (CSC) failure test2014In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 58, p. 16-24Article in journal (Refereed)
    Abstract [en]

    Low temperature cracking of asphalt pavements is associated to the thermal stresses created when asphalt binder changes from a ductile into a brittle state during cooling. Under repetitive traffic loads, this change of properties can become a significant problem, resulting in the formations of large cracks on the driving surface, thus requiring early pavement repair. Nevertheless, the conventional test methods for assessing low temperature properties of bitumen are often insufficient and subject to low reproducibility. Therefore, a reliable method is necessary to characterize the performance of bituminous binders at low temperature. This work presents the cyclic shear cooling failure test (CSC-failure test) as an alternative method based on a failure test with the dynamic shear rheometer (DSR) at decreasing temperature until fracture occurs. Operational parameters, like shear strain amplitude or loading frequency, have been analysed in order to develop a reproducible procedure applicable for different types of bituminous binders. Moreover, a failure criterion has been defined by analysing the different characteristic temperatures from the failure curves obtained in the test.

  • 11.
    Chen, Feng
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Taylor, Nathaniel
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Dynamic application of the Inductive Power Transfer (IPT) systems in an electrified road: Dielectric power loss due to pavement materials2017In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 147, p. 9-16Article in journal (Refereed)
    Abstract [en]

    Inductive Power Transfer (IPT) technology is seen as a promising solution to be applied in an electrified road (eRoad) to charge Electric Vehicles (EVs) dynamically, i.e. while they are in motion. Focus in this study was placed on the dielectric loss effect of pavement surfacing materials on the inductive power transfer efficiency, induced after the integration of the technology into the physical road structure. A combined experimental and model prediction analysis was carried out to calculate this dielectric loss magnitude, based on which some preliminary conclusions as well as a prioritization of future focus needs were summarized in detail.

  • 12.
    Chen, Feng
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Taylor, Nathaniel
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Dynamic application of the Inductive Power Transfer (IPT) systems in an electrified road: Dielectric power loss due to pavement materials2016In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526Article in journal (Other academic)
    Abstract [en]

    It is well-known that the high cost and limited performance of existing energy storage systems have significantly constrained the commercialization of the Electric Vehicle (EV) at large scale. In recent years, attention has been given not only to the improved energy storage systems but also to develop appropriate charging infrastructures that would allow the EVs to be powered in an easier way. Inductive Power Transfer (IPT) technology, also known as a near-field wireless power transfer technology, is capable of delivering electricity wirelessly with large power and high efficiency at a given gap distance. It is therefore seen as a promising solution to be applied in an electrified road (eRoad) to charge EVs dynamically, i.e. while they are moving. Various technical aspects of this contactless charging solution have been studied actively by system developers, such as the charging power, its efficiency, the optimum gap distance as well safety issues. Focus in this study is placed on the effect of pavement surfacing materials on the wireless power transfer efficiency, after the integration of the technology into the physical road structures. Specifically, a combined experimental and model prediction analysis has been carried out to investigate this potential energy loss in a quantitative way, based on which some preliminary conclusions as well as a prioritization of future focus needs are summarized in detail. This work provides thus an important beginning for understanding the pavement materials’ influence on the IPT systems that may be used for dynamic applications in an eRoad.

  • 13.
    Damineli, Bruno L.
    et al.
    Univ Sao Paulo, Inst Architecture & Urbanism, BR-13566590 Sao Carlos, Brazil.;Univ Sao Paulo, Polytech Sch, Dept Construct Engn, BR-05508900 Sao Carlos, Brazil..
    Pileggi, Rafael G.
    Univ Sao Paulo, Polytech Sch, Dept Construct Engn, BR-05508900 Sao Carlos, Brazil..
    Lagerblad, Björn
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    John, Vanderley M.
    Univ Sao Paulo, Polytech Sch, Dept Construct Engn, BR-05508900 Sao Carlos, Brazil..
    Effects of filler mineralogy on the compressive strength of cementitious mortars2021In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 299, article id 124363Article in journal (Refereed)
    Abstract [en]

    Substituting cement with fillers is crucial to formulate cost-effective cementitious materials with low CO2 emissions. However, despite limestone, there is a lack of knowledge of fillers from other mineralogical sources for use in cementitious pastes. This study investigates the effects of characteristics of fillers from 6 mineralogical sources on the reactivity and compressive strength of the cementitious pastes, which could allow increasing industrial possibilities. The filler density and the paste total bound water content allowed to determine the paste porosity, which has a much better fit with the compressive strength than the water-binder ratio.

  • 14.
    Das, Prabir Kumar
    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.
    Evaluation of the low temperature cracking performance of asphalt mixtures utilizing HMA fracture mechanics2013In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 47, p. 594-600Article in journal (Refereed)
    Abstract [en]

    In the present study, the low temperature cracking performance of asphalt mixture has been investigated numerically and experimentally. To do so, the HMA thermal fracture model has extended by including fracture energy threshold and non-linear thermal contraction coefficient. This extended model is capable to predict thermally induced stress and fracture temperature, which is validated with experimental results obtained from three different types of asphalt mixtures. From the parametric study, it was observed that understanding the influence of thermal contraction coefficient, the cooling rate and the creep compliance parameters can make a significant contribution to the material's sustainability. From the analysis, it was found that this extended model can be utilized to evaluate the low temperature cracking performance of asphalt mixtures and capable to provide correct ranking. Interestingly, non-linear thermal contraction coefficient gave much better prediction than linear approach.

  • 15.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Tasdemir, Yuksel
    Bozok University, Engineering and Architecture Faculty.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Low temperature cracking performance of WMA with the use of the Superpave indirect tensile test2012In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 30, p. 643-649Article in journal (Refereed)
    Abstract [en]

    Low temperature cracking of wax modified bitumen and asphalt mixtures were studied using the Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR), Superpave IDT and Thermal Stress Restrained Specimens Test (TSRST). Two types of commercial waxes (FT-paraffin and Asphaltan-B) were added to 70/100 penetration grade bitumen. Hot Mix Asphalt (HMA) fracture mechanics was used to determine fracture parameters. Master curves obtained from DSR and BBR test results showed stiffening effect due to wax additive at low temperature. The analysis of covariance was performed using a General Linear Model (GLM) on the Superpave IDT test results for Energy Ratio (ER) by using SPSS (Statistical Program for Social Sciences). Statistical analysis of Superpave IDT results showed a minor negative effect of wax modification at lower temperatures. Statistical analysis also showed that fracture parameters are highly temperature dependent and the two types of aggregate used did not play any significant role in low temperature cracking performance. Results obtained from TSRST tests indicate wax modification has a minor negative effect in low temperature cracking performance of asphalt mixtures.

  • 16.
    Draganovic, Almir
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Karamanoukian, Antranik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Ulriksen, Peter
    Lund Univ, Dept Biomed Engn, Div Engn Geol, SE-22100 Lund, Sweden..
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Dispersion of microfine cement grout with ultrasound and conventional laboratory dissolvers2020In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 251, article id UNSP 119068Article in journal (Refereed)
    Abstract [en]

    Grout based on microfine cement is mainly used for sealing of rock fractures in underground construction with high sealing requirements. This grout is known as hard dispersed, compared to grouts based on ordinary Portland cement. This study investigates the possibility of using ultrasound to improve the dispersion of microfine cement grout. Ultrasound dispersion is compared with dispersion efficiency of an ordinary laboratory mixer equipped with a disk, and using the rotor-stator technique. Dispersion efficiency was measured with a filter pump. The grout dispersed with the laboratory mixer and disk could not pass through a 154 mm filter. The laboratory mixer using the rotor-stator technique showed much better efficiency, with a measured dispersion that varied between 77 and 104 mm. Dispersion with ultrasound yielded more reliable results, with lower variation; the grout passed through a 77 mm filter. These results showed that a laboratory mixer with a disk is not an effective method for dispersion of microfine cement. A laboratory mixer using the rotor-stator method is much more effective. Ultrasound is not only an effective method but is even better than a mixer using the rotor-stator technique.

  • 17.
    Draganovic, Almir
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Karamanoukian, Antranik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Ulriksen, Peter
    Lund Univ, Dept Biomed Engn, Div Engn Geol, SE-22100 Lund, Sweden..
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Ultrasonic dispersion of hard dispersed ultrafine milled cement-based grout for water sealing of fractured hard rock2022In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 317, article id 125869Article in journal (Refereed)
    Abstract [en]

    Ever higher demands on the sealing of rock around underground structures drive the development of cement based grouts. The results of the previous study demonstrated that it is possible to mill cement to approximately 20 to 25 mu m and use it to seal fracture aperture down to approximately 70 mu m. Further milling deteriorates the penetrability of the grouts due to the flocculation of the fine particles. This study investigates ultrasound as a technique to improve dispersion of grouts based on ultrafine milled cement. The grout tested is based on cement where 95% of the cement mass has particles smaller than 12 mu m and is very hard to disperse. Dispersion with ultrasound is compared with a conventional laboratory mixer equipped with a disk and rotor-stator system. The dispersion efficiency of this mixing equipment was tested by a filter pump. The results confirmed that a conventional laboratory mixer equipped with a disk is not at all suitable for dispersion of this grout. The laboratory mixer equipped with a rotor-stator system is much better than a disc but still cannot disperse this fine milled grout properly. Ultrasound was found to be the most effective method. The dispersion achieved, measured with a filter pump, was around 54 mu m which indicates that it is possible to seal fracture aperture now down to 54 mu m, which is a significant improvement.

  • 18.
    Draganović, Almir
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Lagerblad, Björn
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Filtration of silica particles from a low-pH cementitious grout2016In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 105, p. 29-34Article in journal (Refereed)
    Abstract [en]

    Spent nuclear fuel is stored in rock depositories. Swelled bentonite around the stored capsules prevents eventual spread of radioactive material by ground water. The pH-value of the ground water in contact with bentonite shall be less than 11 not to affect the swelling capacity of the bentonite. Therefore cementitious grout with low pH-value is used to grout these depositories. There is a risk that pH-value of this grout can locally increase due to filtration at fracture constriction and influence pH-value of ground water. Chemical SEM EDAX-analysis indicates that there is no risk of increasing of PH-value in this grout.

  • 19.
    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.
    Rheological effects of commercial waxes and polyphosphoric acid in bitumen 160/220: High and medium temperature performance2007In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 21, no 10, p. 1899-1908Article in journal (Refereed)
    Abstract [en]

    The effects of adding three commercial waxes and a polyphosphoric acid to three bitumens of 160/220 penetration grade were studied using different types of laboratory equipment, such as Dynamic Shear Rheometer (DSR), Differential Scanning Calorimeter (DSC), Force Ductilometer (FD) as well as equipment for determining conventional parameters like penetration, softening point and Fraass breaking point. The paper deals with effects at medium and high in-service temperatures likely to affect the rutting performance of an asphalt concrete pavement. The results show that magnitude and type of effect on bitumen theology depend on the bitumen as well as type and amount of additive used. Bitumen composition was found to be of decisive importance. Adding polyethylene wax or polyphosphoric acid especially to a non-waxy bitumen, showed considerable positive effects on the theological behaviour at medium and higher temperatures.

  • 20.
    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 N.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    A New Viscoelastic Micromechanical Model for Bitumen-Filler Mastic2020In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 253, article id 119062Article in journal (Refereed)
    Abstract [en]

    A new micromechanical model for predicting viscoelastic properties of mastic is proposed and validated with experiments. The developed model is based on the finite element method and allows predicting the viscoelastic properties of mastic by means of the fundamental mechanical and geometrical properties of its constituents. The influence of modelling parameters on the model’s accuracy is evaluated and optimal parameter combinations are identified. It is shown that the proposed model can capture the measured viscoelastic behaviour of mastics for the range of loading, temperature and material parameters examined. Accordingly, it may be a useful tool for optimizing mastics material design meeting the target viscoelastic properties.

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  • 21. 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.
    Experimental evaluation of dense asphalt concrete properties for induction heating purposes2013In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 46, p. 48-54Article in journal (Refereed)
    Abstract [en]

    Induction heating of asphalt concrete is a technique that has been recently developed to increase the self-healing rates of asphalt concrete. It consists in adding electrically conductive fibers to the asphalt mixture and heating them with an induction heating device. In this way, the temperature of asphalt concrete can be indirectly increased. But still, the factors that affect the increase of temperature are not well-known. With the purpose of finding them, 25 different mixtures, with the same aggregates distribution and amount of bitumen, but with two different lengths, four different quantities, and four different diameters of steel wool fibers have been considered. The influence of fibers on the air void content, electrical and thermal conductivity of dense asphalt concrete has been studied. Furthermore, the effect of these properties on the maximum temperature reached after a fixed time induction heating is analysed. It was found that steel wool fibers increase slightly the electrical and thermal conductivities of dense asphalt concrete. Additionally, in the case of the thermal conductivity, an increase on the volume of steel wool fibers serves to compensate the loss in the thermal conductivity that happens when the air void content is increased. Finally, it has been observed that the temperature reached due to the induction heating increases with the number of fibers in the mixture and with their diameter. As a recommendation, it is indicated that, for induction heating purposes, short fibers, with big diameters should be used.

  • 22. García, A.
    et al.
    Bueno, M.
    Norambuena-Contreras, J.
    Partl, Manfred N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Induction healing of dense asphalt concrete2013In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 49, p. 1-7Article in journal (Refereed)
    Abstract [en]

    Induction heating can be used for repairing cracks in asphalt concrete. With this purpose, electrically conductive particles have to be added to the asphalt mixture, which is then heated with an induction heating device. Since the factors affecting the induction healing of dense asphalt concrete are not well-known, in this article, different mixtures, with different lengths, quantities and diameters of steel wool fibres have been considered. It was found that there is a minimum temperature for healing asphalt concrete. Additionally a semi-empirical model, explaining asphalt healing through the capillary theory has been developed and fitted to the results.

  • 23. García, A.
    et al.
    Norambuena-Contreras, J.
    Partl, Manfred N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Schuetz, P.
    Uniformity and mechanical properties of dense asphalt concrete with steel wool fibers2013In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 43, p. 107-117Article in journal (Refereed)
    Abstract [en]

    Fibers in asphalt concrete are known for enhancing its strength and fatigue characteristics while increasing ductility. Additionally, fibers may increase the dynamic modulus, moisture resistance, creep compliance, rutting and freeze-thaw resistance of asphalt concrete, preventing the formation and propagation of cracks. The addition of fibers may influence the properties of the material, but it is not clear how is this influence, and which are the optimum amount, length and diameter of fibers needed for not having a negative impact on the mixture. For this reason, fibers (steel wool) distribution and their effect on the porosity and electrical conductivity of dense asphalt concrete have been studied. With that purpose, 25 different mixtures, with the same aggregates gradation and amount of bitumen, but with two different lengths of fibers, four different percentages, and four different diameters of steel wool have been built. Results show that long and thin fibers produce many clusters and a poor distribution, while short and thick fibers disperse very well in the mixture. It was also observed that fibers can be seriously damaged during the mixing and compaction processes. Finally, it has been found that steel wool fibers do not have a relevant influence on the particle loss resistance and flexural strength of dense asphalt concrete.

  • 24.
    Ghafoori Roozbahany, Ehsan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials. VTI Swedish National road and transport research institute, Olaus Magnus väg 35, Linköping, 583 30, Sweden.
    Partl, Manfred
    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.
    Modelling the flow of asphalt under simulated compaction using discrete element2019In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 227, article id 116432Article in journal (Refereed)
    Abstract [en]

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

  • 25.
    Ghafoori Roozbahany, Ehsan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Partl, Manfred N.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Guarin, Alvaro
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Particle Flow during Compaction of Asphalt Model Materials2015In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 100, no 15, p. 273-284Article in journal (Refereed)
    Abstract [en]

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

  • 26. Granne, F.
    et al.
    Björk, Folke.
    KTH, Superseded Departments (pre-2005), Civil and Architectural Engineering.
    Joints between roofing felt and sheet metal flashings - short- and long-term tests2000In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 14, no 07-jun, p. 375-383Article in journal (Refereed)
    Abstract [en]

    The adhesion between roofing felt and sheet metal flashings has been measured and analysed and test methods for this have been developed. Both bituminous and polymeric roofing felts have been used. The steel has been PVC-coated galvanised steel sheets and the bituminous roofing felts have been of both SBS and APP modified type. All the joints have been made with heat welding. The tests show that it is possible to obtain joints with sufficient strength using the contractors ordinary welding procedures.

  • 27. Granne, F.
    et al.
    Björk, Folke.
    KTH, Superseded Departments (pre-2005), Civil and Architectural Engineering.
    Noreng, K.
    Wind load resistance tests of heat-welded joints between roofing felt and sheet metal flashings2003In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 17, no 5, p. 319-324Article in journal (Refereed)
    Abstract [en]

    The wind load resistance of joints between roofing felt and sheet metal has been measured in a wind uplift chamber. Both bituminous and polymeric roofing felts have been used. The sheet metal has been PVC-coated galvanised steel sheets and the bituminous roofing felts have been of both SBS and APP modified type. All the joints have been made by heat welding. The tests show that peeling is the dominating process in the failure of joints during wind load.

  • 28.
    Guarin, Alvaro
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Khan, Abdullah
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Butt, Ali Azhar
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science. Aston University School of Engineering and Applied Science, Aston Triangle, Birmingham, United Kingdom.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    An extensive laboratory investigation of the use of bio-oil modified bitumen in road construction2016In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 106, p. 133-139Article in journal (Refereed)
    Abstract [en]

    Several roads in Iceland with bio-oil modified surface dressings exhibited severe distresses such as bleeding, binder drain down, and eventually as surface dressing sticking to tires. Samples from six road sections were evaluated in the laboratory to determine the causes of the failure. Binders with and without bio-oil, rapeseed oil and fish oil, were evaluated through a comprehensive rheological and chemical characterization. Both oils, exhibited solubility issues with the bitumen; consequently, the oils covered the aggregates, preventing bonding between binder and stones. It appears that fish oil worked a little better than rapeseed oil for binder modification.

  • 29.
    Gudmarsson, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Rydén, Nils
    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.
    Observed deviations from isotropic linear viscoelastic behavior of asphalt concrete through modal testing2014In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 66, p. 63-71Article in journal (Refereed)
    Abstract [en]

    The complex Young's moduli, complex shear moduli and complex Poisson's ratio of a beam shaped asphalt concrete specimen have been characterized through low strain (similar to 10(-7)) frequency response function measurements. The assumption of isotropic linear viscoelastic behavior has been applied and investigated. The results indicate that the asphalt concrete specimen agree with the isotropic linear viscoelastic assumption at low temperatures and high frequencies (>10 kHz at 0 degrees C), but at higher temperatures and lower frequencies, discrepancies from isotropic linear behavior are shown. The dynamic shear moduli calculated from the estimated Young's moduli and Poisson's ratio of the asphalt concrete specimen are overestimated for frequencies and temperatures often applied to pavements.

  • 30.
    Gudmarsson, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Rydén, Nils
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Di Benedetto, H.
    Sauzéat, C.
    Complex modulus and complex Poisson's ratio from cyclic and dynamic modal testing of asphalt concrete2015In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 88, p. 20-31Article in journal (Refereed)
    Abstract [en]

    The complex moduli and complex Poisson's ratio of two cylindrical asphalt concrete specimens have been determined through modal testing in this paper. These results have been compared to cyclic tension-compression measured complex moduli and complex Poisson's ratio of asphalt concrete specimens with different dimensions. The modal testing has been performed by measuring frequency response functions of the specimens using an impact hammer and an accelerometer. The material properties have been characterized by matching finite element computed frequency response functions to the measurements. The results of the different specimens show that the modal test systematically give a slightly higher absolute value of the complex moduli compared to the cyclic testing. The differences are most likely a result of the different strain levels applied in the two test methods. However, the modal and cyclic tension-compression testing resulted in similar values of the complex Poisson's ratio for the two different asphalt concrete mixtures despite the different applied strain levels.

  • 31.
    Hailesilassie, Biruk W.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Hugener, Martin
    Partl, Manfred N.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Influence of foaming water content on foam asphalt mixtures2015In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 85, p. 65-77Article in journal (Refereed)
    Abstract [en]

    Warm mix asphalt technology using foamed bitumen is being used widely despite the fact that high air void content and poor coating of large aggregate remain major drawbacks require enhancement. This paper manly focuses on the investigation of water content influence on the foamed bitumen and the asphalt mixture. Influence of the water content in combination with compaction temperature has been investigated using gyratory compaction method. AC11N foam asphalt mixture is produced in the lab using lab foamer. Marshall stability and indirect tensile test was used to evaluate the foam asphalt mixture performance. The investigation revealed that the Marshall stability of foam asphalt mixture is highly influenced by compaction temperature compared to water content. Moreover, increasing the water content helps in coating large aggregates when the mixture is produced at low temperature, nevertheless using high water content reduces the Marshall stability to certain extent. In addition the amount of water trapped in the mixture after the mixing process was determined using thermogravimetric analysis. The amount of water remaining in the asphalt mixture is less than 1% relative to the bitumen mass.

  • 32.
    Hailesilassie, Biruk Wobeshet
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Partl, Manfred
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Adhesive Blister Propagation under an Orthotropic Bituminous Waterproofing Membrane2013In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 48, p. 1171-1178Article in journal (Refereed)
    Abstract [en]

    In most countries, waterproofing systems used on concrete bridge decks or roofs of buildings are generally based on orthotropic bituminous membranes; amongst these, styrene-butadiene-styrene copolymer (SBS) and atactic polypropylene (APP) polymer modified bituminous membranes are being used in most applications. One of the main technical concerns is the formation of blisters under the membrane caused by a complex mechanism governed by bottom-up pressure and loss of adhesion. This paper intends to contribute in understanding this mechanism by mechanical elastic modeling and experimental investigation. In order to study the material properties of SBS membranes under the in-plane complex stress state, the orthotropic mechanical behavior of a polymer modified bitumen membrane (PBM) was determined from biaxial test data. Hence, the measured stress-strain data were analyzed using the orthotropic equation to find the material properties in the longitudinal and transversal direction. Finally, blister tests were performed on concrete plates for studying adhesive blister propagation by applying controlled pressure between the PBM and the concrete plates. It was found that the ratio of the longitudinal to transversal adhesive blister propagation is comparable to the ratio of the modulus of elasticity in the longitudinal to transversal direction. Due to the orthotropic material property of the PBM, elliptical adhesive blister propagation was observed and a new model proposed for determining the energy for elliptical adhesive blister propagation.

  • 33.
    Hesami, Ebrahim
    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.
    Kringos, Nicole
    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.
    An empirical framework for determining asphalt mastic viscosity as a function of mineral filler concentration2012In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 35, p. 23-29Article in journal (Refereed)
    Abstract [en]

    Sufficient coating, easy paving and good compaction are desirable parameters, which are approachable with the optimum viscosity of the mastic. In many studies, models have been developed for calculating the viscosity for different types of suspensions at various particle-to-fluid ratios. Unfortunately, none of them are applicable to asphalt mastics, since this material has a much wider range of mineral filler concentration from dilute to very concentrate. To give an overview of the existing viscosity models and to evaluate their range of applicability to asphalt mastics, an extensive literature review was performed. A new empirical framework was developed that removes some of the stipulated limitations of the existing theories.

  • 34. Jeoffroy, E.
    et al.
    Bouville, F.
    Bueno, M.
    Studart, A. R.
    Partl, Manfred N.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials. Swiss Federal Laboratories for Materials Science and Technology, Switzerland.
    Iron-based particles for the magnetically-triggered crack healing of bituminous materials2018In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 164, p. 775-782Article in journal (Refereed)
    Abstract [en]

    Bituminous road pavements may suffer from cracking over the years due to repeated stresses. In this study, we compare the effect of different sizes and chemical compositions of magnetically-responsive iron-based particles used as additives to heat up road pavements and thus to close cracks. By applying an alternating magnetic field (AMF), we found that there is an optimal size depending on the particle electrical conductivity at which the temperature on the surface of asphalt samples is the highest. Even when particles are well-distributed after mixing, we found that asphalt samples containing larger particles display inhomogeneous heating during the exposure to the AMF. The mechanical recovery of samples during a double torsion test before and after the exposure to the AMF confirmed the healing capability of asphalt materials containing iron-based particles. Based on these results we provide guidelines for the design of magnetically-responsive asphalts for road pavements of enhanced durability.

  • 35. Jeoffroy, E.
    et al.
    Koulialias, D.
    Yoon, S.
    Partl, Manfred N.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials. Swiss Federal Laboratories for Materials Science and Technology, Switzerland.
    Studart, A. R.
    Iron oxide nanoparticles for magnetically-triggered healing of bituminous materials2016In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 112, p. 497-505Article in journal (Refereed)
    Abstract [en]

    Healing of micro-cracks is crucial for recovering the mechanical properties and extending the service time of bituminous materials. However, crack closure is often challenged by the efficiency and repeatability of the healing process or its technical and economic feasibility for large-scale applications. Here, we propose an innovative method to close micro-cracks in bituminous materials by using magnetically-triggered iron oxide nanoparticles as heating agents. Heating is generated through the so-called hyperthermia effect upon exposure of the nanoparticles to an external oscillating magnetic field. When mixed in a low volume fraction of 1% within bitumen, the nanoparticles generate enough heat to decrease the viscosity of the surrounding material and thus promote crack closure. Oleic acid is used to coat the iron oxide nanoparticles and enable their homogeneous distribution in the bitumen. Because of high hysteresis losses, γ-Fe2O3 nanoparticles with a mean crystallite size of 50 nm exhibited specific absorption rates (SAR) as high as 285 W/g when subjected to a magnetic field of 30 mT at 285 kHz. In contrast to the relatively slow heating of electrically-conductive additives, we find that iron oxide nanoparticles pre-embedded in bitumen allows for crack closure in a few seconds when subjected to similar magnetic field conditions. This represents a new efficient way to heal damage in thermoplastic road pavements in the presence of mineral aggregates.

  • 36.
    Jiang, Yuchen
    et al.
    Taihu Univ Wuxi, Coll Civil Engn, Wuxi 214064, Peoples R China..
    Crocetti, Roberto
    KTH, School of Architecture and the Built Environment (ABE).
    CLT-concrete composite floors with notched shear connectors2019In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 195, p. 127-139Article in journal (Refereed)
    Abstract [en]

    The aim of the paper is to gain data on the mechanical behaviour of CLT-concrete composite floors and subsequently to check if commonly adopted analysis methods are suitable for this particular type of structure. The studies are conducted through laboratory tests, analytical models and numerical modelling. In the shear tests, the notched connections presented considerable stiffness and shear capacity, and failed eventually with shear fracture in the concrete. The bending test results showed that the CLT-concrete composite floors with notched connections had a very high composite action. At the moment of failure, all notched connections along the span remained nearly undamaged, and only one fine concrete crack appeared at the notch near the support. The paper also presents a theoretical calculation method based on the well-known gamma-method, which is suitable for CLT-concrete composite floors. In particular, for the composite floors with 5-layer-CLT panel, a model using a combined distributed stiffness is introduced to take account of the stiffness of both the mechanical fasteners and the CLT's cross layer, which extends the validity range of the gamma-method to composite systems made of CLT panels with more than three layers. Three-dimensional FE-models for CLT-concrete notched connections and for composite floors are developed using the commercial finite element programme ABAQUS. With the FE-models calibrated with experimental results, parametric studies are conducted to investigate the influence of the notch depth on the mechanical performance of both notched connections and CLT-concrete composite floors. It is concluded that the stiffness of notched connections increases linearly with the depth of the notch, while it is not this case for the shear capacity. The variation of notch depth within the investigated range, i.e. 15 mm to 35 mm, is found to have no significant influence on the load-deflection response of composite floors. 

  • 37.
    Khan, Abdullah
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Redelius, Per
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Evaluation of adhesive properties of mineral-bitumen interfaces in cold asphalt mixtures2016In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 125, p. 1005-1021Article in journal (Refereed)
    Abstract [en]

    The performance of asphalt mixtures is strongly influenced by the physical and chemical properties of the minerals and binders used, at various micro to macro scales. In cold asphalt mixtures a process that particularly strongly influences adherence between the minerals and binders (and thus performance) is the wetting of bitumen on the minerals’ surfaces. Their adhesion is influenced by numerous factors and parameters, such as surface free energies of both binders and aggregates in the presence of moisture or dust on the surface of aggregates, mixing temperatures, surface textures including open porosity, nature of the minerals and their surface chemical composition, as well as additives present in the binder phase. However, the relationships involved are not fully understood. Thus, iowever

    n this study the surface free energies of both minerals/aggregates and binders were characterized using two approaches, one based on contact angles and the other on vapor sorption methods. Precise specific surface areas of four aggregates and seven minerals were determined using BET (Brunauer, Emmett and Teller) theory, by measuring the physical adsorption of selected gas vapors on their surfaces, and calculating amounts of adsorbed vapors corresponding to monolayer occupancy on the surfaces. Interfacial bond strengths between bitumen and aggregates were also calculated, based on measured surface free energy components of minerals/aggregates and binders, in both dry and wet conditions. The adhesive bond strength for the binder with each mineral/aggregate combination in wet condition has been improved by using additives. The presented study has highlighted the need for accurate measurements of aggregates’ and minerals’ specific surface areas and (hence) requirements to develop new approaches to resolve problems associated with BET-based methods.

     

  • 38. Li, Tao
    et al.
    Cheng, Da-li
    Avramidis, Stavros
    Wålinder, Magnus
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Zhou, Ding-guo
    Response of hygroscopicity to heat treatment and its relation to durability of thermally modified wood2017In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 144, p. 671-676Article in journal (Refereed)
    Abstract [en]

    In an attempt to study the effect of heat treatment on hygroscopicity and durability of wood, Poplar (Populus spp.) wood was thermally modified using five different temperatures between 170 degrees C and 210 degrees C, for a fixed duration of 3 h. Moisture adsorption behavior and the resistance to soft rot fungi were investigated thereafter. Based on the Hailwood-Horrobin sorption model, the amount of available sorption sites within specimens for the different groups of Poplar wood were calculated from the model's m(0) parameter. Chemical analysis of the changes in wood components induced by heat treatment allows for a comparison between the easily obtained m(0) and the results of time-consuming wood decay tests. The proposed m(0)-based method for highly efficient evaluation and prediction of durability of thermally modified wood could optimize future research on the mechanisms of heat treatment processes.

  • 39.
    Ling, Senlin
    et al.
    Tongji Univ, Key Lab Rd & Traff Engn, Minist Educ, Shanghai 200092, Peoples R China..
    Itoua, Prince Igor
    Tongji Univ, Key Lab Rd & Traff Engn, Minist Educ, Shanghai 200092, Peoples R China..
    Sun, Daquan
    Tongji Univ, Key Lab Rd & Traff Engn, Minist Educ, Shanghai 200092, Peoples R China..
    Elaguine, Denis
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Damage characterization of pouring semi-flexible pavement material under triaxial compressive load based on X-ray computed tomography2022In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 348, article id 128653Article in journal (Refereed)
    Abstract [en]

    Pouring semi-flexible pavement (SFP) material is a multi-phase composite material with complex damage characteristics and strength mechanism. Therefore, revealing the shear properties and damage characteristics of SFP is essential for understanding the strength formation mechanism of SFP and guiding the design of SFP. Firstly, the effect of porous asphalt mixture (PAM) air void on the shear properties of SFP was analyzed by triaxial compressive tests, and the Mohr-Coulomb theory was applied to analyze the shear strength mechanism of SFP. Then, the pore and crack distribution characteristics of SFP specimens at different loading stages were investigated via X-ray CT. Finally, three damage parameters (D-V, D-C, D-E) were used to describe the damage degree of SFP specimens in different loading stages. The results show that increasing the air void of PAM can effectively improve the triaxial compressive strength and compressive modulus of SFP. The Mohr-Coulomb failure criterion can accurately describe the failure behavior of SFP at 60 C. Increasing the air void of PAM can increase the proportion of interlocking force provided by aggregate-cement contact, which in turn increases the internal friction angle of SFP. When the air void of PAM is 25 %, SFP has the largest proportion of cement -asphalt-aggregate (C-AS-A) interface area, leading to the largest cohesion force of SFP. Moreover, during triaxial compression, C-AS-A interface crack accounts for 63.47 %, which is the main failure mode of SFP. The plane porosity, volume and surface area of 3D pores and cracks of SFP specimens increase with the increase of vertical deformation. The D-E can more accurately characterize the damage status of SFP.

  • 40.
    Ling, Senlin
    et al.
    KTH, School of Architecture and the Built Environment (ABE). Tongji Univ, Key Lab Rd & Traff Engn, Minist Educ, Shanghai 200092, Peoples R China..
    Jelagin, Denis
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Sun, Daquan
    Tongji Univ, Key Lab Rd & Traff Engn, Minist Educ, Shanghai 200092, Peoples R China..
    Fadil, Hassan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Experimental and numerical analyses on the fracture characteristics of cement-asphalt mastic-aggregate interface2023In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 401, article id 132971Article in journal (Refereed)
    Abstract [en]

    The stiffness and failure properties of cement-asphalt mastic-aggregate (C-AM-A) interface are among the most important factors affecting the performance of pouring semi-flexible pavement materials (SFP). Therefore, determining the characteristics of C-AM-A interface are essential for guiding the design of SFP from the perspective of interface enhancement. In this study, the failure characteristics of C-AM-A interfaces are examined experimentally and numerically. Firstly, the effects of temperature and the proportion of cement substituting limestone filler on the bonding strength of C-AM-A interface are analyzed via pull-off tests. Then, an innovative test method based on a three-point bending test of C-AM-A beam is proposed to investigate the influence of test temperature and asphalt mastic type on the fracture characteristics of the C-AM-A interface. Finally, based on the cohesive surface techniques, numerical modeling of C-AM-A beam under three-point bending was applied to study the effect of cohesive parameters on the interfacial fracture characteristics. The results show that the interface bonding strength decreased significantly with the increase of temperature. Using cement as a filler improves the bonding strength, fracture strength, stiffness and fracture energy of C-AM-A interface as compared to the case when limestone filler is used. As the temperature increases from -10 degrees C to 20 degrees C, the failure mode of the C-AM-A interface first alters from adhesive failure to mixed failure mode, and then to cohesive failure. It suggests that enhancing the adhesion of C-AM-A interface is more advantageous for improving the fracture resistance at low temperatures, while increasing the interface cohesion is more important at relatively high temperatures. The laboratory test methods, the numerical model and methodology developed in this study are useful to study the failure behavior of C-AM-A interface and optimize the performance of SFP from the perspective of interface enhancement.

  • 41.
    Ling, Senlin
    et al.
    Tongji Univ, Key Lab Rd & Traff Engn, Minist Educ, Shanghai 200092, Peoples R China..
    Sun, Yu
    Tongji Univ, Key Lab Rd & Traff Engn, Minist Educ, Shanghai 200092, Peoples R China..
    Sun, Daquan
    Tongji Univ, Key Lab Rd & Traff Engn, Minist Educ, Shanghai 200092, Peoples R China..
    Elaguine, Denis
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Pore characteristics and permeability simulation of porous asphalt mixture in pouring semi-flexible pavement2022In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 330, article id 127253Article in journal (Refereed)
    Abstract [en]

    Filling grouting material into the voids of porous asphalt mixture (PAM) is one of the important steps in the construction of pouring semi-flexible pavement (SFP), and the pore characteristics play a dominant role in the slurry permeability performance of PAM. Therefore, understanding the influence of pore characteristics on the slurry permeability performance and revealing the penetration mechanism of grouting materials in the void of PAM are essential for guiding the design of PAM used in SFP and improving the quality and efficiency of the grouting construction. Firstly, the effects of porosity and aggregate size on slurry permeability and water permeability of PAM are experimentally studied. Then, the 3D pore structure parameters, such as porosity, equivalent diameter, coordination number, pore throat dimension and tortuosity are quantitatively and statistically analyzed via X-ray CT and 3D reconstructed model. Finally, the slurry permeability simulation of PAM is conducted. The results show that the porosity and aggregate size have a significant influence on the complexity and spatial anisotropy of the pore structure of PAM. Increasing the porosity and aggregate size can effectively increase the connected porosity ratio, 3D pore size and throat size of PAM, while reduce the number of small pores (D-3d < 1 mm(2)) and isolated pores. Besides, the slurry and water permeability coefficients of PAM are also positively correlated with the porosity and aggregate size. Moreover, to be consistent with the real condition, the slurry permeability coefficient is more suggested as the technical index of PAM to ensure the perfusion effect of PAM. In the simulation, the slurry permeability values in the vertical direction are higher than those in the horizontal direction. The pore characteristics are ranked according to their effect on the seepage of grouting material: connected porosity > pore size and throat size >> pore coordination number (CN) and tortuosity.

  • 42.
    Lövqvist, Lisa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Zhu, Jiqing
    VTI.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Evaluation of the standard test method for resistance of bituminous materials to de-icing  fluidsIn: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526Article in journal (Refereed)
    Abstract [en]

    As an important maintenance measure, de-icing agents are commonly used to ensure safe surface conditions of highways and airport runways during winter. There are however issues related to their use, such as deteriorating effects on road materials, causing particle loss and a decreased low-temperature stiffness of asphalt pavements. To avoid this, it is therefore important to be able to evaluate the effect of the deicer on the asphalt mixture with reliable results. The European standard method for this, EN12697-41, is however associated with several issues such as a high variability of the results and a lack of consistency with the field. Using both experimental testing and numerical simulations, this paper aims to explain the cause of these and to identify the main dominant parameters which can potentially be modified for an improvement. The experimental testing evaluated both the diffusive properties of de-icing fluid and water in mastic and the standard method itself, and the numerical simulations evaluated the effect of different parameters related to the set-up of the test. From the evaluations, it was concluded that both the set-up of the test and the geometryof the test sample contribute to the high variability of the test method and its lack of consistency with the field. Recommendations are therefore made regarding the potential for improvement and further evaluation of the method.

  • 43.
    Lövqvist, Lisa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Zhu, Jiqing
    Swedish Natl Rd & Transport Res Inst, Olaus Magnus Vag 35, S-58330 Linköping, Sweden..
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Evaluation of the standard test method for resistance of bituminous materials to de-icing fluids2021In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 308, article id 124929Article in journal (Refereed)
    Abstract [en]

    As an important maintenance measure, de-icing agents are commonly used to ensure safe surface conditions of highways and airport runways during winter. There are however issues related to their use, such as deteriorating effects on road materials, causing particle loss and a decreased low-temperature stiffness of asphalt pavements. To avoid this, it is therefore important to be able to evaluate the effect of the deicer on the asphalt mixture with reliable results. The European standard method for this, EN12697-41, is however associated with several issues such as a high variability of the results and a lack of consistency with the field. Using both experimental testing and numerical simulations, this paper aims to explain the cause of these and to identify the main dominant parameters which can potentially be modified for an improvement. The experimental testing evaluated both the diffusive properties of de-icing fluid and water in mastic and the standard method itself, and the numerical simulations evaluated the effect of different parameters related to the set-up test. From the evaluations, it was concluded that both the set-up of the test and the geometry of the test sample contribute to the high variability of the test method and its lack of consistency with the field. Recommendations are therefore made regarding the potential for improvement and further evaluation of the method.

  • 44.
    Ma, Ziye
    et al.
    Changan Univ, Sch Highway, South 2nd Ring Rd Middle Sect, Xian 710064, Shaanxi, Peoples R China..
    Wang, Hainian
    Changan Univ, Sch Highway, South 2nd Ring Rd Middle Sect, Xian 710064, Shaanxi, Peoples R China..
    Hui, Bing
    Changan Univ, Sch Highway, South 2nd Ring Rd Middle Sect, Xian 710064, Shaanxi, Peoples R China..
    Jelagin, Denis
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    You, Zhanping
    Michigan Technol Univ, Dept Civil & Environm Engn, 1400 Townsend Dr, Houghton, MI 49931 USA..
    Feng, Ponan
    Changan Univ, Sch Highway, South 2nd Ring Rd Middle Sect, Xian 710064, Shaanxi, Peoples R China..
    Optimal design of fresh sand fog seal mortar using response surface methodology (RSM): Towards to its workability and rheological properties2022In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 340, article id 127638Article in journal (Refereed)
    Abstract [en]

    As a popular preventive maintenance material, sand fog seal (SFS) could fill the micro-cracks and improve the skid-resistance and wear-resistance of road surface, but little research has been conducted to explain how the components of fresh SFS mortar affect its workability and rheological behavior. In this paper, an improved workability evaluation system is established for fresh SFS mortar based on self-developed devices, including the basic indexes such as dynamic uniformity DUt,s, slump flow X, and seepage velocity V-s. There is a negative correlation between the fluidity index (slump flow and seepage velocity) and the uniformity index (dynamic uniformity), and both of them are important bases for the performance balance design of fresh SFS mortar. Then, the effects of water, filler and sand on the workability are evaluated using response surface methodology (RSM) with I-optimal design method. The results show that water mainly regulates the consistency of the SFS mortar, which in turn affects its flowability. The sodium bentonite filler could alter the suspension capacity of the fog seal paste and determine the state of dispersion of sand in the paste. Besides, the addition of sand plays a negative role in the fluidity of fresh SFS mortar. Meanwhile, three design intervals for fresh SFS mortar are proposed based on its workability, (1) Easy-to-separate interval: DUt,s < 0.8; (2) Hard-to-flow interval: X <= 54.9 mm and V-s = 0. (3) Recommended interval: DUt,s > 0.8, V-s > 0, and X > 54.9 mm, where the fresh SFS mortar can balance stability and fluidity well. Hence, to maximize the balance between uniformity and fluidity of fresh SFS mortar, a formulation design optimization guideline is proposed based on desirability optimization methodology (DOM). The formulation has the widest distribution of high desirability when the sand content is 25%. Finally, the results of rheological test show that fresh SFS mortar is a typical shear-thinning pseudoplastic fluid, which can fit the "Herschel-Bulkley" model well. Yield stress and plastic viscosity can be used as the important rheological indexes to predict the workability of fresh SFS mortar. In general, based on the approach proposed herein, an optimized fresh SFS mortar with both good uniformity and fluidity could be produced.

  • 45.
    Ma, Ziye
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering. School of Highway, Chang'an University, South 2nd Ring Road Middle Section, Xi'an, Shaanxi, 710064, China, South 2nd Ring Road Middle Section, Shaanxi.
    Wang, Hainian
    School of Highway, Chang'an University, South 2nd Ring Road Middle Section, Xi'an, Shaanxi, 710064, China, South 2nd Ring Road Middle Section, Shaanxi.
    Li, Yuanle
    School of Highway, Chang'an University, South 2nd Ring Road Middle Section, Xi'an, Shaanxi, 710064, China, South 2nd Ring Road Middle Section, Shaanxi.
    Yang, Xu
    School of Highway, Chang'an University, South 2nd Ring Road Middle Section, Xi'an, Shaanxi, 710064, China, South 2nd Ring Road Middle Section, Shaanxi.
    Leng, Zhen
    Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong.
    Optimized bio-oil emulsification for sustainable asphalt production: A step towards a low-carbon pavement2024In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 419, article id 135218Article in journal (Refereed)
    Abstract [en]

    Bio-oil, derived from biomass, offers a sustainable alternative to petroleum-based asphalt binders in construction. However, its high oxygen content and temperature sensitivity pose challenges. This study explored the possibility of using emulsification technology to produce and apply emulsified bio-asphalt at a relatively low-temperature, aiming for sustainable high-value utilization. Three preparation processes were proposed in this study, including modification followed by emulsification (Process A), emulsification followed by modification (Process B), and separate emulsification followed by mixing (Process C). Based on the thermal characteristics of bio-oil, the optimal emulsification temperature was determined to be 80 ± 1 ℃. Through an I-optimal experimental design combined with response surface methodology (RSM), the influence of bio-oil and emulsifier on the performance of emulsified bio-asphalt was investigated for each process. It was found that Process C can leverage the low-temperature extensibility and interfacial adhesion benefits of bio-oil to prepare stable emulsified bio-asphalt with superior comprehensive performance. Based on desirability optimization methodology, the study optimized bio-oil and emulsifier content. The recommended composition is 10.37% bio-oil and 3.53% emulsifier for Process C. Through practical observation, emulsified bio-asphalt production offered environmental benefits, reducing emissions of CO2 and harmful gases, particularly VOCs and NOx. Additionally, adopting bio-oil aligned with carbon neutrality goals, potentially sequestering 880,000 tons of carbon annually in China's road construction and maintenance activities.

  • 46.
    Onifade, Ibrahim
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Damage and Fracture Characterization of Asphalt Concrete Mixtures using the Equivalent Micro-crack Stress ApproacIn: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526Article in journal (Refereed)
    Abstract [en]

    In this paper, a new parameter termed ”equivalent micro-crack stress” (σmc) is proposed for characterizingthe cracking performance of asphalt mixtures. The ”equivalent micro-crack stress” (σmc) is a function ofthe material stiffness and a critical micro-crack initiation threshold (MCIT). The ”equivalent micro-crackstress” (σmc) takes a similar form as the failure stress obtained from the Griffith energy balance equation.The MCIT incorporates the influence of the fracture work and the size and spatial distribution of the airvoids in the determination of the material cracking performance. Experimental tests are carried out toobtain the (σmc) to characterize the cracking performance of unmodified and wax modified mixtures usingthe Superpave IDT tests at low temperature range (i.e. -20oC, -10oC and 0oC). The result shows that the ”equivalent micro-crack stress” (σmc) gives a good indication of the material cracking performance ofthe unmodified and wax modified mixtures. The result of numerical simulations of the fatigue behaviouralso shows that the relationship between the number of cycles to micro-crack formation (Nmc) and σmc can be used to distinguish the wax modified mixtures from the unmodified mixture.

  • 47.
    Onifade, Ibrahim
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Birgisson, B.
    Damage and fracture characterization of asphalt concrete mixtures using the equivalent micro-crack stress approach2017In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 148, p. 521-530Article in journal (Refereed)
    Abstract [en]

    In this paper, a new parameter termed “equivalent micro-crack stress” (σmc) is proposed for the evaluation of the cracking performance of asphalt mixtures with respect to their resistance to the initiation of micro-crack. The “equivalent micro-crack stress” (σmc) is a function of the material stiffness and the “micro-crack initiation threshold” (MCIT). The MCIT is a critical strain energy density at the instance of initiation of micro-crack. Experimental testing is carried out for the evaluation of the cracking performance of unmodified and wax modified asphalt mixtures using the Superpave IDT tests at −20 °C, −10 °C and 0 °C. The low temperature range is used in the study to minimize the effect of viscoplastic dissipation on the material cracking behaviour. The result shows that the “equivalent micro-crack stress” (σmc) gives a good indication of the material cracking performance of the unmodified and wax modified mixtures. A Finite Element Analysis is performed to assess the validity of the proposed approach under cyclic loading condition in the controlled-stress mode. The result shows that there is a good agreement between the material cracking performance in both monotonic and cyclic loading conditions using the proposed approach. The higher the “effective micro-crack stress” (σmc), the better the fracture performance of the mixture.

  • 48.
    Partl, Manfred
    et al.
    Road Engineering/Sealing Components Laboratory, EMPA Duebendorf, Duebendorf, Switzerland.
    Pasquini, E.
    Canestrari, Francesco
    Virgili, A.
    Analysis of Water and Thermal Sensitivity of Open Graded Asphalt Rubber Mixtures2010In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 24, no 3, p. 283-291Article in journal (Refereed)
    Abstract [en]

    This research investigates the water and thermal sensitivity of two open graded mixtures prepared with asphalt rubber binder, one mixture containing lightweight aggregates (expanded clay) replacing a part of coarse fraction. Fatigue tests using the CoAxial Shear Test (CAST) apparatus were performed in both dry and wet conditions with and without temperature cycles. Results showed that fatigue resistance of the studied materials was only little affected by water and temperature cycles and superior to traditional open graded mixtures produced with SBS modified bitumen only. The results were also validated and modelled by means of an elasticity-based damage model.

  • 49.
    Peñaloza, Diego
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Erlandsson, Martin
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Falk, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Exploring the climate impact effects of increased use of bio-based materials in buildings2016In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 125, p. 219-226Article in journal (Refereed)
    Abstract [en]

    Whenever Life Cycle Assessment (LCA) is used to assess the climate impact of buildings, those with high content of biobased materials result with the lowest impact. Traditional approaches to LCA fail to capture aspects such as biogenic carbon exchanges, their timing and the effects from carbon storage. This paper explores a prospective increase of biobased materials in Swedish buildings, using traditional and dynamic LCA to assess the climate impact effects of this increase. Three alternative designs are analysed; one without biobased material content, a CLT building and an alternative timber design with “increased bio”. Different scenario setups explore the sensitivity to key assumptions such as the building's service life, end-of-life scenario, setting of forest sequestration before (growth) or after (regrowth) harvesting and time horizon of the dynamic LCA. Results show that increasing the biobased material content in a building reduces its climate impact when biogenic sequestration and emissions are accounted for using traditional or dynamic LCA in all the scenarios explored. The extent of these reductions is significantly sensitive to the end-of-life scenario assumed, the timing of the forest growth or regrowth and the time horizon of the integrated global warming impact in a dynamic LCA. A time horizon longer than one hundred years is necessary if biogenic flows from forest carbon sequestration and the building's life cycle are accounted for. Further climate impact reductions can be obtained by keeping the biogenic carbon dioxide stored after end-of-life or by extending the building's service life, but the time horizon and impact allocation among different life cycles must be properly addressed.

  • 50. Poulikakos, L.
    et al.
    Partl, Manfred
    Empa, Swiss Federal Laboratories for Material Testing and Research, Dübendorf, Switzerland.
    Evaluation of Moisture Susceptibility of Porous Asphalt Concrete Using Water Submersion Fatigue Tests2009In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 23, no 12, p. 3475-3484Article in journal (Refereed)
    Abstract [en]

    Porous asphalt concrete due to its open structure is exposed to water and therefore susceptible to water damage. Effect of water, temperature and frequency on mechanical properties of porous asphalt concrete was investigated. An innovative test method developed in Switzerland is used to mechanically test 150 mm diameter cylindrical cores from eight materials in dry state and while being submerged under water. Although the conventional indirect tensile strength ratio delivers useful data about the water sensitivity of porous asphalt specimen, the coaxial shear test provides vital information about the development of fatigue damage in the material. Application of coaxial shear test (CAST) for a twin lay porous asphalt as well as conventional porous asphalt shows a reduction in complex modulus due to fatigue loading after each thermal cycle and due to detrimental effects of water Submersion. Moisture susceptibility results using CAST reflected the field inspections of surface degradation. In addition, investigation of the microstructure has given insight into the mechanical behavior of selected materials.

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