33 results on '"Blom, Johan"'
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2. Teraflows over Gigabit WANs with UDT
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Grossman, Robert L., Gu, Yunhong, Hong, Xinwei, Antony, Antony, Blom, Johan, Dijkstra, Freek, and de Laat, Cees
- Published
- 2005
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Catalog
3. Native 10 Gigabit Ethernet experiments over long distances
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Meirosu, Catalin, Golonka, Piotr, Hirstius, Andreas, Stancu, Stefan, Dobinson, Bob, Radius, Erik, Antony, Antony, Dijkstra, Freek, Blom, Johan, and de Laat, Cees
- Published
- 2005
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4. Exploring practical limitations of TCP over transatlantic networks
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Antony, Antony, Blom, Johan, de Laat, Cees, and Lee, Jason
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- 2005
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5. Mitigation of zinc leaching from waste ground tire rubbers through polymer encapsulation.
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Adeel, Muhammad, Fishel, Yanou, Blom, Johan, Dardenne, Freddy, Michielsen, Bart, Bergmans, Jef, Van Nueten, Lorenz, Vuye, Cedric, Vande Velde, Christophe M.L., and Billen, Pieter
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CRUMB rubber , *RUBBER waste , *WASTE recycling , *SYNTHETIC sporting surfaces , *COATING processes , *TIRE recycling , *RUBBER , *WASTE tires - Abstract
• Polymer coatings can reduce crumb rubber zinc leaching. • Polyethylene wax and polyurethanes can be used for outdoor applications. • Methylene diisocyanate polyurethanes perform best due to pi-stacking. • The use of additives to these coatings further decreases zinc leaching. The increasing disposal of waste tires is a growing environmental challenge requiring innovative recycling and reuse approaches. Crumb rubber, derived from end-of-life tires, has potential for various applications where resilience and elasticity are required. However, as highlighted by the upcoming ban on using crumb rubber granulate as infill for artificial turf in the EU, one of the most prominent issues, zinc leaching, urgently requires an effective solution. We studied a range of commercial polymer coatings as a zinc leaching barrier through batch and column leaching tests. This study demonstrates that coatings can reduce the leaching down to 1 % of that of uncoated rubber, reducing environmental risks while improving the prospects for continued use of crumb rubber in various applications. The physico-chemical relation between the coating structure and zinc leaching is elucidated for the most promising coatings by comparing the leaching results with FTIR, GPC and 1H NMR analyses. The use of certain additives shows a cumulative effect to further reduce zinc leaching, while improving UV- and moisture stability. Thermal stability is controlled by the stability of the polymer base. These findings allow us to tailor the mechanical properties to various applications requiring specific elasticity and durability, while retaining the versatility and adaptability of crumb rubber in a range of scenarios. Additionally, the use of additives, typically cheaper than the polymer matrix, enhances the economic viability. By effectively controlling zinc leaching and tailoring mechanical properties through coatings, this study offers a way to extend the life and utility of waste rubbers. [ABSTRACT FROM AUTHOR] more...
- Published
- 2025
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6. Microscopic examination of TCP flows over transatlantic links
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Antony, Antony, Blom, Johan, de Laat, Cees, Lee, Jason, and Sjouw, Wim
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- 2003
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7. Does the wet addition of crumb rubber and emission reduction agents impair the rheological performance of bitumen?
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Borinelli, Jaffer Bressan, Blom, Johan, Vuye, Cedric, and Hernando, David
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CRUMB rubber , *GREENHOUSE gas mitigation , *FATIGUE limit , *RHEOLOGY , *STRAINS & stresses (Mechanics) , *BITUMEN , *CHARCOAL , *RUBBER - Abstract
Crumb rubber modified bitumen (CRMB) is a promising solution for recycling waste tyres and improving asphalt performance. Nonetheless, higher temperatures are usually required during mixing, which increases the emission of volatile organic compounds (VOCs) that can potentially cause harmful health effects on workers due to their toxic and carcinogenic properties. Emission reduction agents (ERAs) have been developed to address this issue. However, limited scientific evidence is available regarding their impact on the rheological performance of CRMB, which makes the selection of the most suitable ERA challenging. This study investigated the effects of three ERAs on the physical and rheological properties of CRMB: steam-activated carbon/charcoal (AC), fly ash-based geopolymer (GFA), and Portland cement paste (PCP). In addition to penetration and softening point tests, a dynamic shear rheometer (DSR) was used to evaluate the rheological properties of the samples in the frequency and temperature domains and to perform the multiple stress creep recovery (MSCR) and linear amplitude sweep (LAS) tests. The results revealed that the three ERAs increased the stiffness of CRMB: penetration reduced and softening point, penetration index, and viscosity increased. This stiffening effect caused a drop in the fatigue resistance measured in the LAS test. Out of the three ERAs evaluated, AC clearly induced the greatest changes in binder properties. However, MSCR results, crossover frequency, R-value, Glower-Rowe parameter, and ΔT c were less sensitive to the addition of ERAs. It was concluded that the addition of GFA and PCP did not impair the physical and rheological properties of CRMB, yielding results comparable to those of a PMB. However, AC may introduce issues during mixing and service life due to the increase in viscosity and the reduction in fatigue resistance. [Display omitted] • ERAs enhanced CRMB stiffness, lowering penetration, elevating softening point and viscosity. • Increased stiffness induced by ERAs led to decreased fatigue resistance of CRMB. • AC significantly affected binder properties, posing challenges in mixing and service life. • Jnr, %R, crossover frequency, R-value, Glower-Rowe parameter, and ΔTc were less ERA-sensitive. • GFA and PCP additions do not compromised CRMB properties, offering results comparable to PMB. [ABSTRACT FROM AUTHOR] more...
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- 2024
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8. Use of early acoustic emission to evaluate the structural condition and self-healing performance of textile reinforced cements.
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El Kadi, Michael, Blom, Johan, Wastiels, Jan, and Aggelis, Dimitrios G.
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ACOUSTIC emission , *ACOUSTIC emission testing , *STRUCTURAL health monitoring , *REINFORCED cement , *TEXTILES , *LAMINATED materials - Abstract
Textile reinforce cements (TRC) are innovative materials that are used for repair of existing structures or recently as stand-alone lightweight structural members. Fracture and thermal behavior of these materials are very complicated due to multiple failure modes. The undergoing processes cannot be described by the simple constitutive equation. In this perspective the contribution of monitoring techniques is crucial. Acoustic emission (AE) is used to check the behavior of TRC beams and plates in different states of structural health: intact, thermally pre-cracked and self-healed by polymer powder. This is the first time that the AE behaviors of intact, cracked and self-healed TRC laminates are compared in literature. [ABSTRACT FROM AUTHOR] more...
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- 2017
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9. Effect of curing conditions on the dimensional and thermal stability of calcium phosphate cement for elevated temperature applications.
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Blom, Johan, Rahier, Hubert, and Wastiels, Jan
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CURING , *THERMAL stability , *CALCIUM phosphate , *HIGH temperature physics , *THERMOPLASTICS , *WOLLASTONITE - Abstract
Calcium phosphate cements (CPCs) are attractive materials for elevated temperature applications, like moulds to process thermoplastics up to 300 °C. The CPC resulting from the reaction of wollastonite with phosphoric acid cured at room temperature however contains hydrated phases like brushite, and is thus not stable when exposed to temperatures above 200 °C. A non-contact method based on digital image correlation demonstrated that isothermal curing at 60 °C reduces the thermal shrinkage up to 300 °C by 25%. This curing method results in the direct formation of the more stable monetite in a shorter curing time. The correlated results of TGA, pH of the filtration water, and DSC analysis on partially cured material indicate this. XRD diffractograms and SEM images in combination with EDX show the evolution of the transformation of wollastonite into monetite, and the structure and morphology of the formed material. [ABSTRACT FROM AUTHOR] more...
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- 2014
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10. Coupling AFM and CLSM to investigate the effect of ageing on the bee structures of bitumen.
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Pipintakos, Georgios, Blom, Johan, Soenen, Hilde, and Van den bergh, Wim
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- 2021
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11. New evidence on the origin of 'bee structures' on bitumen and oils, by atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM).
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Blom, Johan, Soenen, Hilde, Van den Brande, Niko, and Van den bergh, Wim
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ATOMIC force microscopy , *BEE products , *LASER microscopy , *ATOMIC force microscopy techniques , *BITUMINOUS materials , *BITUMEN , *BEES , *NEONICOTINOIDS - Abstract
[Display omitted] • CLSM is complementary to AFM when investigating bee structures. • A mixture of alkanes, differing in melting points, can create islands around the bee structures. • Bee structures are not limited to bitumen and can be created on maltenes and mineral oil surfaces. • No bee structures are observed on surfaces in contact with glass or water. • In the bulk of a mineral oil sample waxes crystallize as small particles. Bitumen is a complex mixture whose composition–structure-property relationships are not well-understood. Therefore, it is essential to understand which components may develop microstructures, how and when these features appear, and if they are initiated or influenced by other components. Many studies have reported so-called bee structures as well as other phases on bitumen surfaces. A large number of observations point towards the crystallinity of waxy compounds as an explanation for the bees. However, doubt remains about the origin of the other phases and the possibility of other bitumen components as promoters of the bee formation. In this study, bee structures were investigated using two microscopy techniques: atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). By using model wax compounds, especially blends of waxes differing in melting points and chain lengths, bee structures and surrounding islands were created on featureless bitumen surfaces. Structures very similar to what is observed on a paraffinic bitumen were obtained. This indicates that bees and the surrounding areas both consist of crystallisable components. Moreover, bee structures were also generated on other surfaces, such as mineral oil and a maltene fraction. Bee formation is not limited to bituminous materials and bitumen components are not needed as promotors. Furthermore, CLSM offers possibilities to scan through transparent layers and to investigate surfaces under glass, for example. In contact with such a solid substrate, as well as after water submersion, no microstructural features were observed. Adding a combination of n-alkanes, to transparent oil, induced bee structures at the oil-air interface. The transparency of the oil allowed the visualization of wax crystallization in the bulk, where the added waxes crystallize as small particles. These small crystals are expected to influence the mechanical properties, such as low-temperature stiffening effects, which have been reported for paraffinic bitumen. [ABSTRACT FROM AUTHOR] more...
- Published
- 2021
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12. Influence of aggregates, glass fibre reinforcement and recycled aggregates on polyester mortar.
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Van Thillo, Lotte, Blom, Johan, Moreels, Alex, and Craeye, Bart
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MORTAR , *FIBERS , *UNSATURATED polyesters , *PARTICLE size distribution , *POLYMER aggregates , *IMPACT strength , *POLYESTERS - Abstract
• A smaller fraction of coarse sand results in higher strength. • Angular aggregates provide superior interlock effects. • Glass fibre reinforcement doubles the impact resistance. • Recycled polymer mortar aggregates result in higher tensile and impact strength. As the performances of unsaturated polyester mortar are related to its composition, this research is focused on the influence of the grain size distribution of the aggregates, glass fibres reinforcement and the use of recycled aggregates on its mechanical and physical properties and microstructure. It revealed that a higher fraction of coarse sand caused a decrease in compressive (2 to 3%), tensile splitting (10 till 14%) and flexural tensile (5 to 9%) strength since the interlocking effects decrease, while microstructure analysis reveals more cracks and air voids when the filler fraction is substituted. Moreover, the addition of a small amount of glass fibres, i.e. 0.20 vol%, resulted in a decrease of 0.9, 3.4 and 4.6%, respectively, in compressive, tensile splitting and flexural tensile strength, whereas the impact toughness doubled. The properties related to the microstructure indicate that this mixture is less compacted compared to a mixture without fibre reinforcement, although the ultrasonic pulse velocity increased with 2.5%. Furthermore, the study highlights the potential of recycled polymer mortar as aggregates since enhanced tensile (18.5 and 3.9% respectively, for tensile splitting and flexural tensile strength) and impact properties (an improvement of 41.8%) were observed, while the additional tests indicate that the mixture with recycled aggregates has a less dense structure compared to the reference mixture. [ABSTRACT FROM AUTHOR] more...
- Published
- 2021
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13. Investigating thermal and UV ageing effects on crumb rubber modified bitumen enhanced with emission reduction agents and carbon black.
- Author
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Borinelli, Jaffer Bressan, Enfrin, Marie, Blom, Johan, Giustozzi, Filippo, Vuye, Cedric, and Hernando, David
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FOURIER transform infrared spectroscopy , *CRUMB rubber , *FLY ash , *CARBON-black , *PRESSURE vessels - Abstract
Over time, bitumen experiences deterioration due to factors like the exposure to oxygen, solar irradiation, and temperature fluctuations. While laboratory techniques like rolling thin film oven (RTFO) and pressure ageing vessel (PAV) were developed to simulate field ageing, they do not accurately replicate environmental factors normally occurring in the field, particularly solar irradiation. Limited research has focused on understanding the ageing processes of crumb rubber modified bitumen (CRMB). This study investigated how different ageing conditions affect the chemo-rheological properties of CRMB and CRMB with geopolymer-based fly ash (GFA), Portland cement paste (PCP), and carbon black (CB). GFA and PCP were added to reduce noxious fumes and VOC emissions from CRMB whereas CB is commonly employed as an antioxidant agent. RTFO and PAV were used to simulate short- and long-term ageing, while a SUNTEST XLS+ weatherometer was used for thermal and UV ageing simulations. A dynamic shear rheometer and attenuated total reflectance Fourier transform infrared spectroscopy were employed for rheological and chemical analysis. Results indicated that extended exposure to thermal conditioning and UV irradiation had the most impact on the chemo-rheological properties of the binders. The incorporation of CR into bitumen enhanced ageing resistance and mitigated the potential for stiffening and embrittlement. The addition of GFA, PCP, and CB to CRMB had a negligible impact on the chemo-rheological properties when subjected to RTFO, PAV, and thermal conditioning. However, following UV ageing, these additives led to a slight increase in carbonyl bonds and greater stiffness compared to pure CRMB • Thermal and UV ageing revealed the highest impact on the rheological parameters of CRMB. • With ageing, stiffness and elasticity in CRMB and CRMB+ERAs noticeably increase. • Incorporating CR into bitumen demonstrated enhanced ageing resistance. • GFA and PCP had minimal impact on CRMB's rheology after RTFO, PAV, and thermal conditioning. • UV ageing acts as a catalyst, intensifying the damage inflicted during thermal ageing. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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14. Ageing of interfacially active components and its effect on emulsion stability as studied by means of high voltage dielectric spectroscopy measurements
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Ese, Marit-Helen, Sjo¨blom, Johan, Førdedal, Harald, Urdahl, Olav, and Rønningsen, Hans Petter
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- 1997
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15. Evaluation of stability ratio in oil-in-water emulsions
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Verbich, Svetlana V., Dukhin, Stanislav S., Tarovski, Andrej, Holt, Øystein, Saether, Øystein, and Sjo¨blom, Johan
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- 1997
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16. Hydrolysis and condensation rates of tetramethyl orthosilicate in alcohol solutions of hydrated metal salts as determined by means of FT-IR spectroscopy
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O¨ye, Gisle, Libnau, Fred Olav, Sjo¨blom, Johan, and Friberg, Stig E.
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- 1997
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17. Colloid chemistry and modern instrumentation in offshore petroleum production and transport
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Sjo¨blom, Johan, Skodvin, Tore, Holt, Øystein, and Nilsen, Finn P.
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- 1997
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18. Video enhanced microscopic investigation of reversible Brownian coagulation in dilute oil-in-water emulsions
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Holt, Øystein, S˦ther, Øystein, Sjo¨blom, Johan, Dukhin, Stanislav S., and Mishchuk, Natalia A.
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- 1997
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19. Influence of secondary and tertiary amines on the stability of stearic acid monolayers
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Ese, Marit-Helen and Sjo¨blom, Johan
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- 1997
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20. Multivariate analysis of the size dependence of monodisperse silica particles prepared according to the sol-gel technique
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Lindberg, Ritva, Sundholm, Go¨ran, Pettersen, Bjørnar, Sjo¨blom, Johan, and Friberg, Stig E.
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- 1997
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21. Complexation between benzoic acid and fatty amines: an adsorption and chemometric study
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S˦ten, Beate Gundersen, Sjo¨blom, Johan, Toft, Jostein, and Kvalheim, Olav M.
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- 1997
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22. The influence of oxidative aging and wax structure on bitumen physical hardening: Insights from model wax compounds.
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Zhang, Haopeng, Soenen, Hilde, Pipintakos, Georgios, Omranian, Seyed Reza, Blom, Johan, UI Abadeen, Ali Zain, Qiu, Yanjun, and Van den bergh, Wim
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PLASTIC scrap , *CASE hardening , *DIFFERENTIAL scanning calorimetry , *LOW temperatures , *PRECIPITATION hardening - Abstract
Physical hardening (PH) significantly affects bitumen's low-temperature performance. This paper investigates the effect of oxidative aging and wax structure on PH using 4-mm dynamic shear rheometer (4-mm DSR) and differential scanning calorimetry (DSC) tests. The results show that the wax chain length has a pronounced effect on the PH. Short-chain waxes, such as C18 and C24 affect the PH while longer-chain n-paraffins like C40 or Sasobit have almost no effect. In addition, the physical hardening index (PHI) is not linearly increasing with wax content but shows a maximum at a particular wax percentage. Wax-doped samples that crystallize before reaching the hardening temperatures typically show a reduced PHI compared to those with crystallization temperatures just below the hardening temperature. When crystallization and melting temperatures are not close to the hardening temperatures, the PHIs are typically reduced. Oxidative aging also influenced the PHI and in most cases the hardening decreased after aging. The highest PHI of almost all investigated samples occurs at 0 °C among the four typical temperatures. This investigation provides insights in the mechanism of PH and in the relations between wax contents, the hardening temperature, and the PHI. It also shows that while long-chain waxes used as warm mix additives, will not cause a PH risk, short-chain waxes present in pyrolyzed waste plastic, for example, should be handled with care. In addition, PH is also crucial for the intermediate service temperatures and not exclusively for thermal cracking at low temperatures. • Short chain waxes, like C18 and C24 will induce physical hardening in bitumen. • Long chain waxes, like C40 have little effect on the physical hardening in bitumen. • In wax-doped bitumen, the PHI shows a maximum at a particular wax concentration. • If waxes crystallize before reaching the PH temperature, their effect on PHI is lower. • After oxidative aging the PHIs of waxy and wax-doped samples typically reduces. [ABSTRACT FROM AUTHOR] more...
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- 2024
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23. Feasibility of using building-related construction and demolition waste-derived geopolymer for subgrade soil stabilization.
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Xie, Jianwei, Zhang, Junhui, Cao, Zhi, Blom, Johan, Vuye, Cedric, and Gu, Fan
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SOIL stabilization , *CONSTRUCTION & demolition debris , *SOIL conditioners , *ENERGY dispersive X-ray spectroscopy , *CARBON emissions , *CRYSTALLINE polymers - Abstract
A high-value utilization approach is essential to improve the utilization rate of building-related construction and demolition waste (brCDW). This study developed a novel approach by synthesizing a brCDW-derived geopolymer to stabilize high liquid limit subgrade soil. The unconfined compressive strength (UCS) test, shear strength test, resilient modulus test, and permanent strain test were conducted to investigate the effects of brCDW-derived geopolymer dosage, curing time, stress state, and moisture condition on the engineering properties of geopolymer stabilized soil. These test results demonstrated that increasing the geopolymer dosage effectively improved the UCS, shear strength and resilient modulus of stabilized soil and reduced the permanent strain of stabilized soil. The 8% brCDW-derived geopolymer provided adequate UCS, shear strength, resilient modulus, and resistance to permanent strain for stabilized soil, which showed the most economical improvement. Mechanistic-empirical models were employed to accurately estimate the stress-dependent resilient modulus and permanent strain of geopolymer stabilized soil at any given stress state. The Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) test were performed to investigate the strengthening mechanism of brCDW-derived geopolymer stabilization of subgrade soil. The SEM test results indicated that the porosity of stabilized soil was significantly decreased when the geopolymer dosage increased to 8%. The EDS test results demonstrated that the predominant gel types generated from the geopolymer stabilization might be Calcium–Aluminum-Silicate-Hydrate (C-A-S-H), Calcium-Silicate-Hydrate (C–S–H), and Calcium-Aluminate-Hydrate (C-A-H) gels. There was also a small amount of Sodium-Alumino-Silicate-Hydrate (N-A-S-H) gel detected in the geopolymer stabilized soil. Finally, the sustainability of brCDW-derived geopolymer stabilization approach was assessed in terms of material production cost, carbon dioxide emission, and energy consumption. The brCDW-derived geopolymer was proven as a sustainable stabilizer for subgrade soil. [ABSTRACT FROM AUTHOR] more...
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- 2024
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24. Emission reduction agents: A solution to inhibit the emission of harmful volatile organic compounds from crumb rubber modified bitumen.
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Borinelli, Jaffer Bressan, Portillo-Estrada, Miguel, Costa, Juliana Oliveira, Pajares, Arturo, Blom, Johan, Hernando, David, and Vuye, Cedric
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CRUMB rubber , *VOLATILE organic compounds , *GREENHOUSE gas mitigation , *ASPHALT , *TIME-of-flight mass spectrometry , *FLY ash - Abstract
Volatile organic compounds (VOCs) in bitumen fumes pose health risks to workers. Adding end-of-life tire crumb rubber (CR) to bitumen increases VOC emissions. To promote cleaner asphalt production, recycled materials like cementitious materials, activated carbon, zeolite, and geopolymers were incorporated into crumb rubber modified bitumen and explored as emission reduction agents (ERAs). Proton-transfer-reaction time-of-flight mass spectrometry was used to compare VOC emissions across blends. ERAs reduced emissions by at least 33%, with Portland cement, activated carbon, and geopolymer-based fly ash achieving up to 58%, 49%, and 48% reduction, respectively. Multivariable regression analyses showed that the BET surface area, BJH adsorption cumulative surface area, BJH desorption cumulative surface area, and average pore diameter of the ERAs were the predominant factors contributing to the reduction of VOC emissions. [Display omitted] • PTR-TOF-MS reveals toluene as the most abundant VOC of CRMB. • Organic and inorganic ERAs reduce total VOC emissions from CRMB. • Physical characteristics of ERAs are correlated to the VOC emissions from CRMB. • ERAs can successfully reduce health hazardous VOCs from CRMB. • Portland cement paste, activated carbon and geopolymer-based fly ash reduced VOC emission from CRMB the most. [ABSTRACT FROM AUTHOR] more...
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- 2024
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25. In-ground and above-ground service life prediction for timber reusability - Progressing towards circular construction.
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Anastasiades, Kostas, Bielen, Hanne, Cantré, Gianni, Audenaert, Amaryllis, and Blom, Johan
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SERVICE life , *TIMBER , *SUPPLY & demand , *WOOD decay , *WOOD , *PREDICTION models - Abstract
The increasing demand for and consumption of wood requires special attention in order to keep the wood industry sustainable. Therefore, timber reuse is presented as a solution to control the demand side. Unfortunately, the perception of timber decay poses a major barrier for reuse practices. Therefore, this article presents a factorised service life prediction model for wooden components that aims to promote their reuse. The model is based on the Australian service life prediction model, Timberlife, and the European CLICK design model's dose-response model. It predicts the potential for reuse of timber components based on their expected and remaining service life. To determine the service life, the model includes factors that differentiate between wood species, soil characteristics, regional climate and how the investigated components are connected to other components. The presented model focuses on in-ground and above-ground fungal decay and is limited to northwestern Europe. Opportunities for further research include, e.g., a further investigation of the soil characteristics' influence on decay, and evaluating the lag time for regions outside northwestern Europe. The presented service life prediction model can increase awareness and support a circular construction industry. • a service life prediction model for wooden components to promote their reuse. • Mapping in-ground and above-ground fungal decay to assess the wood's reuse potential. • Increasing awareness on timber reusability supports a circular construction industry. [ABSTRACT FROM AUTHOR] more...
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- 2024
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26. Comparison of microscopic techniques to study the diversity of the bitumen microstructure.
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Mirwald, Johannes, Hofko, Bernhard, Pipintakos, Georgios, Blom, Johan, and Soenen, Hilde
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- 2022
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27. Utilizing deep learning and advanced image processing techniques to investigate the microstructure of a waxy bitumen.
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Hasheminejad, Navid, Pipintakos, Georgios, Vuye, Cedric, De Kerf, Thomas, Ghalandari, Taher, Blom, Johan, and Van den bergh, Wim
- Subjects
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DEEP learning , *BITUMEN , *FAST Fourier transforms , *IMAGE processing software , *MICROSTRUCTURE , *LASER microscopy - Abstract
• Microstructure of a waxy bitumen is observed by a confocal laser scanning microscope. • A deep learning network is trained to detect the bee patterns in acquired images. • An image processing technique based on the two-dimensional fast Fourier transform is proposed. • Influence of short- and long-term ageing on the microstructure of a waxy bitumen is investigated. Bitumen, also called asphalt binder, is the key component in asphalt mixtures. Studies to investigate the microstructure of this material show a rich morphology, especially the formation of bee structures in bitumen containing wax. Most research in this field has investigated these microstructures using commercial image processing software that needs a manual selection of these patterns to obtain certain characteristics. This study aims to construct a deep-learning-based object-detection model that can detect these bee patterns in the images acquired from bitumen samples using Confocal Laser Scanning Microscopy (CLSM). The CLSM images are then used to determine the morphological properties of the samples. The properties investigated are some typical roughness parameters and the wavelength calculated by a novel image processing technique based on the two-dimensional fast Fourier transform. In addition, these developed methodologies are used to investigate the influence of short-term and long-term ageing on the microstructure of a waxy bitumen. The results show that the trained deep learning model can be used to successfully detect the location, number, and area of the bee structures. The number of bee patterns and the area of the surface they cover are reduced upon ageing. Furthermore, some strong trends are found between the computed roughness parameters and the ageing level of the samples. Finally, the estimated wavelength of the bee patterns increases by ageing bitumen. The successful development and demonstration of these methods show their great potential in analyzing the microscopic images of bitumen taken by CLSM or atomic force microscopy and the enormous opportunities for future research. [ABSTRACT FROM AUTHOR] more...
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- 2021
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28. Application of Atomic Force (AFM), Environmental Scanning Electron (ESEM) and Confocal Laser Scanning Microscopy (CLSM) in bitumen: A review of the ageing effect.
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Pipintakos, Georgios, Hasheminejad, Navid, Lommaert, Caitlin, Bocharova, Anastassiya, and Blom, Johan
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- 2021
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29. Towards an enhanced fatigue evaluation of bituminous mortars.
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Margaritis, Alexandros, Pipintakos, Georgios, Varveri, Aikaterini, Jacobs, Geert, Hasheminejad, Navid, Blom, Johan, and Van den bergh, Wim
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BITUMINOUS materials , *MORTAR , *COMPUTER simulation , *CONFORMANCE testing , *KEY performance indicators (Management) - Abstract
• A new DSR geometry is introduced to evaluate the fatigue resistance of bituminous mortars. • Empirical and phenomenological criteria, as well as energy concepts, were considered in this study. • Energy concepts proved to be more consistent for the fatigue evaluation of bituminous mortars. • A possible PV threshold is introduced (0.001), below which mortars fail due to pure fatigue. The fatigue resistance, as a performance indicator, is of paramount importance for the selection and benchmarking of bituminous materials. The bituminous mortar can be considered as the medium that connects and envelopes the coarse aggregate skeleton, and hence will significantly influence the fatigue resistance at bulk-scale. Therefore this study presents the steps and challenges of a new testing framework to evaluate the fatigue resistance of bituminous mortars. To do so, first, a new test geometry is introduced, which will ensure cohesive failure in a predefined area. The integrity of this sample geometry is assessed theoretically through finite element simulations and by computer tomography scans. Secondly, specimens of the new geometry are evaluated experimentally using a dynamic shear rheometer, where time-sweep tests are performed on two control mortar types under various test conditions. The control mortar types are fabricated using two commercial bituminous binders, one modified and one neat binder, to evaluate the effect of binder type. The test results are comprehensively analysed using fundamental dissipated energy-based concepts but also empirical and phenomenological failure criteria, providing insights into the failure evolution. For the tested mortar types, the analysis shows good convergence with the considered fatigue models. Finally, using dissipated energy concepts led to the most consisted fatigue model, which is independent of binder type and test conditions. [ABSTRACT FROM AUTHOR] more...
- Published
- 2021
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30. Influence of soft binder and rejuvenator on the mechanical and chemical properties of bituminous binders.
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Jacobs, Geert, Margaritis, Alexandros, Hernando, David, He, Liang, Blom, Johan, and Van den bergh, Wim
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STRAINS & stresses (Mechanics) , *CHEMICAL properties , *ASPHALT pavements , *FATIGUE life , *BITUMINOUS materials , *SERVICE life - Abstract
At the end of their service life, asphalt pavements exhibit distresses such as cracking and ravelling due to the aged bituminous binder. The recycling process of reclaimed asphalt should compensate for the deteriorated binder properties. The main objective of this binder study is to compare two common recycling strategies: the use of a softer binder and a rejuvenator. Three recycling percentages, 0%, 40% and 70% of reclaimed asphalt binder were evaluated. All binder blends were prepared with similar penetration and softening point values. In order to simulate binder performance during service life, ageing protocols by means of rolling thin film oven test and pressure ageing vessel were performed. The investigation included both mechanical and chemical tests. A dynamic shear rheometer was used to assess different rheological parameters over an extensive temperature range. Linear amplitude sweep tests were performed to estimate the fatigue resistance at intermediate temperatures. Resistance to permanent deformation was assessed with a multiple stress creep recovery test. Fourier-transform infrared spectroscopy was used to assess the formation of bonds that indicate oxidative ageing after the ageing protocols. Moreover, an optimised method was introduced to calculate the carbonyl index for rejuvenated binders, which also allows to detect the presence of a rejuvenator in a bituminous binder. The results show that the inclusion of rejuvenator results in similar rheological behaviour compared to the application of a soft binder. Furthermore, the rejuvenator improves binder fatigue life without reducing the performance at elevated temperatures. Image 1 • FTIR spectroscopy is an appropriate tool to detect rejuvenator presence. • Current FTIR integration methods can overestimate I C O for rejuvenated binders. • A new and more accurate I C O index is introduced for rejuvenated binders. • The rejuvenator improved the fatigue life of the binders. • The rejuvenator did not deteriorate the performance at high temperatures. [ABSTRACT FROM AUTHOR] more...
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- 2021
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31. Cementitious binders and reclaimed asphalt aggregates for sustainable pavement base layers: Potential, challenges and research needs.
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Costa, Juliana O., Borges, Paulo H.R., dos Santos, Flávio A., Bezerra, Augusto Cesar S., Van den bergh, Wim, and Blom, Johan
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PAVEMENTS , *ASPHALT , *ASPHALT pavements , *PORTLAND cement , *CONCRETE pavements , *ASPHALT modifiers - Abstract
• High replacement levels natural aggregates with reclaimed asphalt lead to lower mechanical properties. • Low mechanical properties can be compensated by increasing the amount of cementitious materials. • Alkali-activated binders can be a suitable binder if adequately designed. Reclaimed asphalt pavement (RAP) has been increasingly used in the past few decades as a replacement of natural aggregates in pavement layers. However, low replacement level is employed, and consequently, large quantities of RAP are still left unused. Researchers often neglect foundation pavement layers, but it has higher prospects to consume recycled materials due to their increased thickness. RAP has inferior properties compared to natural aggregates; therefore, cementitious binders are used to produce a (sub)base layer using high volumes of RAP. This paper reviews the use of RAP aggregates with cementitious materials for pavement foundation layers. Special attention is given to the use of alkali-activated materials (AAM) as a binder in substitution for Portland cement (PC). This review discussed the properties of fresh and hardened RAP in cementitious matrices, as well as changes in the microstructure. The biggest challenge on the use of RAP on both systems, RAP-PC and RAP-AAM, is the bond issues caused by the presence of asphalt on the surface of the aggregates. Some researches addressed how physical or chemical pre-treatments to the RAP could improve the adherence to the paste, but few studies focused on the optimisation of the binder. A literature survey indicated that an optimised mix design, durability studies and life cycle assessment (LCA) are important research needs towards the development of RAP-AAM. Despite the lack of research evidence, RAP-AAM is a promising solution for foundation pavement layers. [ABSTRACT FROM AUTHOR] more...
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- 2020
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32. Identification of ageing state clusters of reclaimed asphalt binders using principal component analysis (PCA) and hierarchical cluster analysis (HCA) based on chemo-rheological parameters.
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Margaritis, Alexandros, Soenen, Hilde, Fransen, Erik, Pipintakos, Georgios, Jacobs, Geert, Blom, Johan, and Van den bergh, Wim
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HIERARCHICAL clustering (Cluster analysis) , *ASPHALT , *PRINCIPAL components analysis , *ONE-way analysis of variance - Abstract
• A large selection of RA binders was chemically and rheologically tested. • Ageing states can be distinguished based on HCA and PCA analyses. • RA binders showing similar basic properties differ in terms of their ageing state. Nowadays, Reclaimed Asphalt (RA) is widely used in pavement applications as part of new asphalt mixtures. To design high-quality asphalt mixes, the RA material and especially the RA binder must be systematically characterised with the purpose to explore its ageing state, especially when RA is added in high rates (above 20%). In this research, chemical (SARA and FTIR ageing indexes) and rheological properties (master curve parameters, Glower-Rowe parameter and ΔΤ c) of a large selection of RA binders (19 samples) were determined to reveal their ageing level. The results of this experimental validation were further analysed statistically to discover clusters of similar chemorheological properties, reflecting in this way their ageing state. The exploratory techniques PCA and HCA were able to detect five clusters of RA binders with different ageing states. The five clusters clearly distinguish the RA binders in groups with statistically different properties, assessed using one-way ANOVA. The method proposed here is a potential tool to "fingerprint" RA binders with similar ageing states, particularly for decision-making strategies, to optimise the use and treatment of RA. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
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33. Professor Stig Erik Friberg 65 years
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Sjo¨blom, Johan
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- 1997
- Full Text
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