1,720,992 research outputs found
Fatigue effects of embedding electric vehicles Charging Units into electrified road
Get PDFA charging infrastructure network for Battery Electric Vehicles (BEV) is more than an option for the transportation scenarios of the next years. From a pavement engineering point of view, this network consists in prefabricated Charging Units (CU) embedded into the road pavement, generating additional questions related to the structural life of the pavements in which the CU are located. Moreover, even if in the available literature few studies describe the structural response of e-road, the long-term performances of pavements are not fully investigated. This is the reason why this research analyzes fatigue behavior of electrified road (e-road) in comparison with traditional road (t-road). In particular, the study is devoted to identifying the number of critical load cycles leading to failure an e-road pavement. As a second stage, the theoretical and numerical results are verified applying the findings obtained during the first stage of the research to a real case study: Viale Forlanini in Milan (Italy), which is an important two carriageway road connecting the city center to the Linate airport. As a result of these analyzes, interesting outcomes were obtained regarding the fatigue effects of embedding CU into road pavement, estimating the service life and demonstrating that CU seems to be compatible with the structural effectiveness of the pavement, as also confirmed by the case study results
Discussing the feasibility of improving fatigue performance of asphalt mixtures by incorporating high recycled asphalt pavement
No full textThe application of Recycled Asphalt Pavement (RAP) is one of the most accepted strategies in pavement communities due to instability in natural sources and environmental issues, however the performance of substitute materials is still the main concern of producers. Structural properties of produced mixtures such as rutting resistance, strength and fatigue life have the main role in the durability of asphalt mixtures which strongly depend on aggregate and bitumen contents. This paper presents a review of recent studies and results on fatigue performance of asphalt mixtures containing different percentages of Recycled Asphalt Pavement (RAP). The aim of this paper is to emphasize the role of RAP in fatigue performance— which is one of the main distresses of bituminous mixtures- of asphalt mixtures and also to highlight benefits and disadvantages (limitation) of using high RAP content in asphalt mixtures. In addition, the possibility of using a high portion of RAP is discussed. Based on literature review, it can be inferred that including RAP could affect the fatigue performance of asphalt mixtures. © 2019 Taylor & Francis Group, London
Improving runway strip performance to fulfill international requirements through eco-efficient soil treatments: Case study of a major italian airport
No full textThe paper presents a case study of a significant intervention conducted on a major Italian airport for improving the structural and functional properties of the runway safety STRIP in order to fulfill specific national and international standards. The STRIP had to accomplish strict requirements in terms of the maximum longitudinal and transversal terrain slope and minimum values of bearing capacity; in particular, soil bearing capacity was identified as the main lack and thus the most urgent action to be carried out in the airport. However, the STRIP itself is located in a very critical area due to its closeness to the runway and several constraints were therefore identified during the design stage. The optimal strategy was identified as the one that minimized the intervention timing and costs, reducing the handling of construction material to/from the airport, avoiding delays to the air traffic, and maximizing the performance of the treated soils in terms of bearing capacity. In this framework, an energy-controlled stabilization technique of in-situ soils was developed. Several measurements, in both laboratory and field environment, were also conducted at different stages: i) before the intervention took place, ii) during the construction stage, and iii) at the conclusion of the work to monitor and validate the expected results. The intervention was able to provide the STRIP areas with a smooth surface presenting terrain slopes and bearing capacity in accordance with the standards. The illustrated methodology could also be applied to other airports saving time, costs, materials, and limiting air traffic delays
Comparative investigation on the reinforcing effects of polymer-based fiber into bituminous mixtures
No full textThis paper reports the results of a laboratory investigation on the reinforcing effects of fibers into bituminous mixtures, in which neat bitumen is used as binder. The investigated fibers were selected in the European market and were composed of polymer compounds. For comparative purposes, a polymer-modified bituminous mixture was included in the study. Laboratory tests investigated compaction characteristics, and mechanical performance of the bituminous mixtures. The results suggest that mixtures bounded with neat bitumen and reinforced with fibers exhibit same performance, or even better, than the one in which polymer-modified bitumen is used
Bituminous Mixtures with High Environmental Compatibility: Laboratory Investigation on the Use of Reclaimed Asphalt and Steel Slag Aggregates
No full textRecycling waste materials is a key issue in sustainable road pavements construction. This is the reason why the efforts of the scientific and technical community are addressed in studying sustainable solutions for producing bituminous mixtures. As a result of these efforts, the use of Reclaimed Asphalt (RA) is becoming a standard practice, even if in Italy the use of RA is limited to a certain content. So the increase of RA content appears to be the new border of the research in this field. At the same time, the scientific literature demonstrates that other recycled materials, such as Steel Slags Aggregates (SSAs), can be used with satisfactory results. To go a step further, the research herein described focused on the evaluation, at the laboratory scale, of the effects of both high amounts of RA (from 15 up to 60% by weight) and RA plus SSAs (from 55 up to 71% by weight). Compaction properties, volumetric characteristics and mechanical performances were investigated. Even if the obtained results are at the laboratory scale and keeping in mind that the research needs an on-site validation, the investigated mixtures seem to be promising for a future development of bituminous mixtures with high environmental compatibility
Numerical Risk Analyses of the Impact of Meteorological Conditions on Probability of Airport Runway Excursion Accidents
No full textA continuous growth in air transport industry over the recent decades increases the probability of occurrence of accidents and consequently the need of aviation risk and safety assessments. In order to assess the risks related to aircraft ground operations, all the influencing variables that can affect the safety of maneuvers should be determined. Generally, catastrophic accidents that occur inside an aerodrome are assigned to the runway incursions and excursions. Incursions are dedicated to all events happening inside the runway (e.g. existence of an obstacle or accident of two aircraft) and excursions are considered for an unsuccessful aircraft operation which leads to surpassing the designated thresholds/borders of the runway. Landing and take-off overruns, as the main excursion events, are responsible for the major recorded incidents/accidents over the past 50 years. Many variables can affect the probability of runway-related accidents such as weather conditions, aircraft braking potential, pilot’s level of experience, etc. The scope of this study is to determine weather-wise parameters that amplify the probability of excursion events. In order to quantify the probability of each type of accidents, the effect of each meteorological variables on the aircraft operation is simulated by RSARA/LRSARA© simulators, released by Aircraft Cooperative Research Program (ACRP). In this regard, specific airports with diverse characteristics (i.e.; landlocked airport, extreme annual operations, extreme runway geometries and weather conditions) are selected as case studies in the analyses. Gusts and wind forces, specifically cross-wind, turned out to be the most dominant weather-wise influencing parameters on the occurrence of runway excursions
Assessing the impact of the slopes on runway drainage capacity based on wheel/path surface adhesion conditions
No full textAircraft braking distance is dependent on the friction between the main gear tires and runway pavement surface. Pavement texture, which is divided into macrotexture and micro-texture, has a noticeable effect upon friction, especially when the surface is wet. A risk analysis framework is developed to study the effects of longitudinal and transverse slopes on the aircraft braking distance in wet runway conditions and their influences on the probability of landing overrun accidents. This framework is operating under various water-film thicknesses, Maximum Landing Weights (MLW), and touchdown speed probability distributions for an acceptable range of longitudinal/transverse slopes and pavement texture depths. A simulator code is developed that initially computes the existing water-film thickness, as the result of intense precipitation, under aircraft main gear (depend on aircraft category) and then applies this variable as one of the main inputs to the aircraft braking distance computation. According to the obtained results, longitudinal gradient does not have a significant effect on the existing water depth on the surface although it affects the flow path length. Furthermore, 1% to 1.5% transverse slope causes rapid drainage of water from the runway surface and considerably decreases the probability of runway excursion accidents
Valorisation of lignin-rich industrial byproduct into half-warm mix reclaimed asphalt with enhanced performance
Get PDFTo promote a circular economy and sustainable development, the possibility of using a lignin-rich industrial byproduct as a partial substitute for asphalt emulsions in road pavements is analysed. A half-warm mix reclaimed asphalt (HWMRA)-type AC 16 surf S, manufactured with 100% reclaimed asphalt pavement, is selected. Substitution percentages of 0% (control mixture), 5%, 10%, 15%, and 20% are employed. The microstructure of the blend of the byproduct and asphalt emulsion is observed using scanning electron microscopy. The water resistance of the mixture is investigated using indirect tensile tests, as well as its volumetric properties. The stiffness, thermal susceptibility by indirect tensile tests, and resistance to permanent deformation by confined uniaxial compression tests and Hamburg wheel tracking tests are also studied. The optimum percentage of byproduct substitution is 5%, resulting in an enhanced HWMRA with a slightly better water resistance, higher resistance to permanent deformation at low and medium environmental temperatures, and higher indirect tensile strength and stiffness than those of the control mix
Application of rejuvenators and virgin bitumen to restore physical and rheological properties of RAP binder
No full textBoth chemical and rheological aspects of aged bitumen in reclaimed asphalt pavement ( RAP) material play an important role in the final performance of bituminous mixtures containing recycled asphalt material. This must be especially considered in the case of pavements containing high RAP content. The use of rejuvenators and/or virgin bitumen in recycled mixtures helps improving the properties of aged bitumen. This research study investigates RAP oxidised bitumen and its possible rejuvenation with virgin bitumen and addition of various additives as rejuvenator agents. Tests were conducted to analyse the chemical, rheological and physical behaviours of several binder mixes before and after laboratory ageing processes. Longterm ageing of rejuvenated binder mixes was also investigated to assess the effectiveness of rejuvenation over time. The results showed that the addition of virgin bitumen and rejuvenators could improve the performance of oxidised bitumen and increase its resistance to further ageing
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