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Use of bio-binders – A possible way towards more sustainable asphalt mixtures
No full textBitumen, as the main binder used for the production of asphalt layers in road constructions, is obtained by distilling crude oil, which, as a fossil fuel, will have limited availability in the future and whose exploitation has a significant negative impact on the environment. The concept of bio-binders has recently been developed and refers to binders for asphalt mixtures containing bio-renewable materials. The paper presents the types of bio-binders, their application, the basic requirements so that they can be used in asphalt layers, as well as the production procedures. The basic physical and chemical characteristics of bio-oil, as well as the significant characteristics of bio-binders and their influence on the aging resistance of modified bitumens are presented. Finally, the impact of the application of bio-binder on the performance of asphalt mixtures is presented, which depends to a considerable extent on the origin of the biomass used for production of bio-binder. Bio-binders generally have a favorable effect on improving the characteristics of asphalt mixtures at low temperatures, but lead to a decrease in the rutting resistance of the mixtures at high temperatures. In addition to this, a description of the application of bio-binders for the rejuvenation of aged bitumen from reclaimed asphalt pavement, which is widely used in the recycling of asphalt mixtures, is presented
Use of Reactive Modifier for Bitumen and Improvement of Asphalt Mixture Performance
No full textAsphalt pavements are nowadays exposed to ever increasing axle loading and changing climate conditions that are primarily manifested in increasing temperatures. The need for improved performance has resulted in the increased use of modified bitumen and development and use of innovative materials that improve performance, particularly on high temperatures. In this study, a novel liquid, low-viscous reactive additive has been used for bitumen modification. The performance of typical asphalt mixture used for base layers on heavily trafficked roads and highways in Serbia with road bitumen B50/70 modified with 3% of an isocyanate-based additive has been compared to the performance of same mixture with PmB 45/80-65. The testing included water sensitivity, resistance to permanent deformation, stiffness and fatigue. The results obtained so far show at least comparable or slightly improved resistance to water and rutting of mixture with additive compared to mixture with PmB. The master curves indicate increased stiffness over the range of operational frequencies/temperatures, while at low temperatures the stiffness is comparable to mixture with PmB
A framework for progress measurement based on integrated monitoring of prerequisites and work performance
No full textThe successful implementation of construction projects necessitates the establishment of an efficient system for
project execution planning and control, with parameters that ensure an effective assessment of the construction work
status, timely detection of variance causes, and reliable trend analysis. In this regard, a set of parameters has been
developed, among which the actual progress of works on a project holds a significant place. Existing approaches to
progress measurement is mostly focused on studying methods for calculating the percentage of completed works
and their applicability to specific types of works and organizational levels. However, key issues persist, such as
delayed identification of variance causes and inadequate method sensitivity to initial variances when damages are
still minor, and potential effects of corrective measures are greatest. Therefore, this paper proposes a framework for
progress measurement based on integrated monitoring of prerequisites for tasks and work performances. While
progress monitoring at the project level is organized within workflows, monitoring within each workflow is provided
for sub-workflows related to ensuring prerequisites, material procurement, and construction work execution.
Visualization of sub-workflows is facilitated through planned and actual cumulative curves of completed works in
percentage, whose interrelationships promptly indicate potential project issues. The application of the proposed
framework ensures better synchronization of construction works, improved control of prerequisites, rapid detection
of causes, along with efficient variance management. The framework includes a clear division of responsibilities for
implementing sub-workflows, where site management and specialized services of a company are responsible for
ensuring prerequisites and material procurement, while production forces of a company primarily handle the
execution of construction works. Such an approach allows for direct determination of issues or quick and efficient
delineation of responsibilities, which represents a common issue in practice. This contributes to the motivation of
employees and enhances the performance of the project management team
Metode za asimilaciju podataka u hidrološkim modelima: primena i ograničenja
No full textUpravljanje rizikom od poplava, pored merenja nivoa, protoka i padavina na slivu, često zahteva alate za podršku u odlučivanju. Najčešće, ti alati se baziraju na hidrološkim modelima kojima se za predviđeni scenario (prognozirane padavine) vrši prognoza protoka i nivoa u rekama na osnovu kojih se mogu praviti planovi za odbranu od poplava. Modeli sa sobom nose dozu neizvesnosti koja je rezultat nepouzdanosti ulaznih podataka (npr. padavina kao pokretača procesa na slivu), procena trenutnog stanja na slivu (nivoi vode, vlažnost zemljišta, stanje snega ako ga ima i slično) i trenutnih parametara modela (hrapavosti u koritima reka, začepljenost propusta, stanja zelenog pokrivača i slično). Kako bi se ta nepouzdanost hidrološkog modela smanjila i omogućilo poboljšanje početnih uslova za prognozu protoka i nivoa u rekama primenjuju se metode asimilacije podataka. U ovom procesu, hidrološki model se pokreće za određeni broj prethodnih dana, za koji su dostupni izmereni podaci o hidrološkim veličinama (protoci i/ili nivoi kao i padavine na kišomerima). Tokom te simulacije stanje modela se koriguje kako bi se rezultati modela uskladili sa izmerenim podacima. Cilj ovog procesa je da se na kraju perioda asimilacije model dovede u stanje koje odgovara izmerenom i time omogući poboljšan početni uslov za dalju prognozu. U ovom radu analizira se primena standardnih metoda za asimilaciju podataka (EnKF, 3Dvar i 4Dvar) i praktična ograničenja ovih metoda. Ispitivanje je sprovodeno na hidrološkom modelu hipotetičkog sliva pokazujući da metoda 4Dvar ima najveći potencijal za primenu u hidrološkim modelima
A Preisach Model Defining Correlation Between Monotonic and Cyclic Response of Structural Mild Steel
No full textThis article delivers a new Preisach model representing the correlation between the elasto-plastic behavior of structural mild steel under axial monotonic and cyclic loading with damage. The
newly formed model is based on the experimentally defined correlation between axial monotonic and cyclic behavior of structural mild steel. To examine the monotonic and cyclic behavior of structural mild steel and find fitting material properties for the model, monotonic and cyclic axial tensile tests
are performed. Tests are executed on coupons of the commonly used European structural steel
S275. The model represents a mathematical description of modified single-crystal material behavior under monotonic loading. Two different approaches were used to describe damage in the multilinear mechanical model. The excellent agreement with experimental results is achieved by infinitely linking many single-crystal elements in parallel, forming the polycrystalline model. This model provides a good solution for everyday engineering practice due to its geometric representation in the form of the Preisach triangle and the lower costs of monotonic tests used to define material properties compared to cyclic tests
Mogućnosti primene prirodom inspirisanih rešenja za urbano odvodnjavanje u Srbiji
No full textU radu je dat osvrt na aktuelne probleme urbanog odovodjavanja sa aspekta
pogoršanja hidrološkog režima usled urbanizacije. Istaknuta je potreba za smanjenjem
negativnih uticaja urbanizacije na količine i kvalitet urbanog oticaja. Prikazane su inovativne
metode urbanog odvodnjavanja i opšte preporuke za njihovu primenu, kao i zahtevi iz
predloga nove direktive EU o gradskim otpadnim vodama koje se odnose na integrisano
upravljanje otpadnim i kišnim vodama u gradovimaThe paper presents challenges that urban drainage has to solve under altering
hydrological regime due to urbanization. The need for reducing the negative impacts of
urbanization on the quantity and quality of urban runoff is emphasized. Innovative methods
of urban drainage have been presented, together with general recommendations for their app
lication. The requirements from the proposal of the new EU Directive on urban wastewater 330
related to the integrated management of urban wastewater, including rainwater, are presented
in more detail
Digitalno modelovanje postojećih stambenih fondova radi procene energetske efikasnosti i cirkularnosti
No full textU današnjem svetu, zgrade su ključni akteri u ekosistemu, trošeći ogromne količine resursa i generišući značajne količine štetnih gasova i otpada. Evropska Unija postavlja visoke ciljeve u dekarbonizaciji, energetskoj efikasnosti i cirkularnosti zgrada, zahtevajući detaljno sagledavanje postojećih zgrada. Digitalna tranzicija postaje ključna poluga u tom procesu, omogućavajući precizno digitalno modelovanje postojećih zgrada i urbanih regija. Ovo istraživanje identifikuje ključne izazove, uključujući prikupljanje obimnih podataka, stvaranje preciznih 3D modela i integraciju semantičkih podataka za preciznu analizu energetske efikasnosti i cirkularnosti zgrada. Metodologija modelovanja jedne urbane regije u Beogradu je prikazana kao studija slučaja
Mapping the urban building stock for a circular economy by integrating GIS and BIM. A case study from Belgrade, Serbia
No full textAssessing the rapidly expanding building stock, particularly at a large urban scale, remains challenging for the circular built environment. The growing use of digital technologies in new building designs has partially addressed it, but estimating existing stock is still a concern. Although numerous models are based on cadaster, building typologies, material intensities, and spatial analysis, their limiting factor is the level of detail. This study presents an innovative methodology that combines the existing estimation models and exploits the potential of remote sensing, 3DGIS, and BIM. The methodology is tested and validated in a municipality district in Belgrade, Serbia, characterized by different building types and fast urban regeneration. The results reveal better estimations of the existing stock at building, element, and material levels. As such, they may serve as a valuable base for pre-demolition audits, resource cadaster, and a support tool in creating a more feasible circular economy and decarbonization strategies
Investigating How Extreme Events Trigger Nexus Effects and Developing a Nexus Methodological Framework to Increase Resilience
No full textClimate change is already increasing the frequency and intensity of extreme events, significantly impacting human societies well being and resilience. This is particularly exacerbated by trends in population growth, urbanization, and land use changes, which often increase the vulnerability and exposure of human systems. In addition, the complexity of modern human systems, such as the interconnectedness of critical entities that support them, makes urban settings especially susceptible to domino effects triggered by a single initial shock.
The aim of this study is to understand and assess the Nexus effects of extreme events related to climate and other natural hazards, such as earthquakes, volcanoes, and tsunamis. An extended Water-Energy-Food Nexus schema is considered, incorporating Ecosystems, Climate, Soil, Transportation, Land Use, Health, and Information and Communication Technologies. The analysis synthesizes practical case studies of actual extreme events that have occurred over the last few decades, primarily in Europe. It considers the implications across three timescales: short-term, mid-term, and long-term. This study employs a modified Nexus-oriented literature review approach, examining nine different types of extreme events, i.e. droughts, earthquakes, floods, heatwaves, landslides, tornadoes, tsunamis, volcanoes, and wildfires. A minimum of three case studies is analyzed for each type of extreme event. For each case study, the Nexus tree approach is applied. The synthesis of the Nexus trees for each extreme event will create the Nexus signature of that specific event. Based on these signatures, an inventory of recommendations for decoupling the nexus interlinkages will be developed. These recommendations will be categorized into operational, tactical, and strategic levels, corresponding to the three impact horizons. Special focus will be given to the implementation of Nature-based Solutions. The ultimate ambition of the NEXUSNET task force is to provide tangible tools and capacity to improve urban resilience against climate change-induced and other extreme events
Rekonstrukcija primarnih raskrsnica u gradu – kritički osvrt na primer rešenja raskrsnice Savske i Nemanjine ulice u Beogradu
No full textPovršinske raskrsnice na primarnim potezima gradske putne mreže predstavljaju najvažnija čvorišta za efikasno odvijanje celokupnog saobraćaja u gradu. S obzirom na njihov značaj u gradskoj saobraćajnoj infrastrukturi, njihovoj rekonstrukciji se mora sistematično pristupiti kroz metodološki jasno utvrđene korake i aktivnosti. Rekonstrukcijom raskrsnice Savske i Nemanjine ulice u Beogradu u sklopu izgradnje novog Savskog trga ništa nije dobijeno u pogledu funkcionalnosti i razrešenja postojećih saobraćajnih problema na ovom delu primarne gradske putne mreže Beograda. Štaviše, nepoštovanjem osnovnih pravila za projektovanje gradskih saobraćajnica u pogledu održanja broja i širine saobraćajnih traka za kretanje primarnih saobraćajnih tokova u kontinuitetu kroz raskrsnicu, saobraćajna slika i postojeći problemi sa kapacitetom su značajno pogoršani. Najveće posledice loše projektovane i izvedene rekonstrukcije ove raskrsnice trenutno trpe saobraćajni tokovi u Savskoj i Karađorđevoj ulici usmereni ka Slaviji kroz Nemanjinu ulicu, ali se negativne posledice posredno prenose i na susedne primarne poteze gradske saobraćajne mreže. Posebno imajući u vidu uočene manjkavosti u koncepciji celokupne saobraćajne mreže koja opslužuje novo naselje “Beograd na vodi“, kao i da je trenutno veliki broj stanova u pomenutom naselju neuseljen, još veći saobraćajni problemi i gužve se nažalost tek mogu očekivati u budućnosti