Search results for "Rubber"
showing 10 items of 146 documents
New simplified approach for obtaining a reliable plateau value in fatigue analysis of bituminous materials
2017
The Plateau Value (PV) based on the Ratio of Dissipated Energy Change (RDEC) approach has been proven to provide a unique relationship with the fatigue life, N-f, independent of loading mode, temperature and frequency. In this paper, a new simplified approach is proposed to compute the unique energy parameter PV. The results of this study show that applying the proposed method allows a unique fatigue power law to be produced and eliminates the ambiguity and variability in calculating PV. However, the study also shows that the PV-N-f fatigue curves for bituminous materials are dependent on material type which is contradictory to other studies dealing with PV. The study also highlights the im…
Can crumb rubber modifier effectively replace the use of polymer- modified bitumen in asphalt mixture?
2021
Laboratory scale mechanical performances on six plant produced mixtures; three semi-dense surface courses and three dense binder courses modified with engineered crumb rubber (ECR) using the dry process are presented. The two types of mixtures produced and investigated fulfilled for the most part, the requirements of the Swiss and/or US standards regarding volumetric properties, water sensitivity and rutting. In advanced testing where no requirements exist, the dense ECR mixtures performed similar to the reference polymer modified mixtures and slightly worse for semi-dense mixtures in high temperature tests, where the binder becomes viscous in the rubber-binder composite and its ability to …
Modeling the influence of mineral content and porosity on ultrasound parameters in bone by using synthetic phantoms
1999
Model composite media − 10×15×80 mm3 bone tissue phantoms based on an epoxy resin with fillers—were made to study the influence of porosity and mineral content on ultrasound velocity and attenuation. The pores were simulated by ∼ 1 mm3 particles of a soft rubber, while the mineral content was imitated by a mineral residue of natural bone obtained by burning and grinding. The porosity and mineral content were varied in the range of 0–70% by volume with a step of 10%. The velocity, attenuation, and prevalent frequency of ultrasound were measured by the pulse transition method, using transducers with nominal frequencies 0.1, 0.2, 0.5, and 1.0 MHz. It was experimentally found that the ultrasoun…
Über die verschiedenen mittelwerte des molekulargewichts und die uneinheitlichkeit von naturkautschuk und synthetischem cis-polyisopren
1969
An Naturkautschuk und einem cis-Polyisopren von annahernd gleichem [η]-Wert wurden Molekulargewichtsbestimmungen durch Diffusion-Sedimentation, Osmose und Lichtstreuung gemacht. Aus den Mittelwerten Mn (osmotisch) und Mw (Lichtstreuung) wird die molekulare Uneinheitlichkeit bestimmt. Bei etwa gleichem Mw (2·106) ist das osmotische Molekulargewicht Mn bei Naturkautschuk 3,0·105 und beim synthetischen cis-Polyisopren 6,2·105. Auserdem macht sich beim Naturkautschuk ein nur schwer entfernbarer Anteil von Mikrogelen bemerkbar. Da die Tragheitsradien und die Wechselwirkungsparameter mit den Losungsmitteln fur Natur- und Synthesekautschuk sich nur wenig unterscheiden, konnen technologische Unters…
Thermomechanical Properties of Radiation-Modified Polyethylene/Ethylene-Propylene-Diene Copolymer/Liquid-Crystalline Copolyester Blends
1999
Radiation-modified blends of high-density polyethylene (PE) with ethylene-propylene-diene copolymer (EPDM; 10-65 wt.%) and thermotropic liquid-crystalline polymer (LCP; 10 wt.%) were investigated. The LCP was a liquid-crystalline copolyester of 40% poly(ethylene terephthalate) with 60% 4-hydroxybenzoic acid. The constituents were blended using a circular extruder, the specimens were prepared by compression molding and irradiated by 60Co γ-radiation up to 200 kGy. Mechanical, thermal, and morphological properties in wide temperature range were investigated for the irradiated and non-irradiated specimens. The effects of irradiation on the thermomechanical behaviour of the PE matrix are discus…
Towards a new mix design method for asphalt mixtures containing rap
2016
Recycling is one of the most important aspects to conceive the new construction or rehabilitation of sustainable road infrastructures. Even if Reclaimed Asphalt Pavement (RAP) is commonly used in the practice, its presence may lead to some critical aspects due to the physical and chemical phenomena occurring during the new mix process. For instance, the formation of RAP clusters during a new mix may inhibit the uniform distribution of the virgin binder as well as cause changes in the design grading curve of the mixture. Indeed, laboratory results demonstrate that small-size RAP particles stick together forming clusters. The amount of clusters depends on different parameters observed: The pe…
An italian research on mechanical properties on asphalt with tire-rubber
2003
In Palermo a research study was initiated with following objectives: characterisation of the asphalt with tire rubber; study of pavements overlaid with this type of asphalt; cost estimation of asphalt rubber production process. This paper describes the first results achieved in the study concerning the mechanical properties of asphalt with tire rubber for road base and base course. In this research on dry process, more than 400 specimens have been tested at the DIIV laboratory for analysing the influences of crumb rubber modifier and powdered rubber modifier on the Marshall and indirect tensile test.
Sustainable Mobility in Park Areas: The Potential Offered by Guided Transport Systems
2012
The project choices to design and manage a transport infrastructure system are extremely hard in thinly populated areas like, for instance, protected areas and mostly parks. In actual fact, the need for promotion and development of these areas, often characterized by large surfaces, contrasts with the necessity to preserve their inestimable natural value. The transportation demand in extremely sensible environmental contexts can be satisfied by providing incentives to use reduced-impact means of transport, regulating adequately the vehicle traffic flow and promoting the intermodality between private and public transport systems. Apart from performing their own traditional functions, these s…
Characterization of rubberized asphalt for railway sub-ballast. Improvements in the mix-design, performance features and rational methodology of HMA_…
2018
(STR) can be incorporated into asphalt mixtures in two different methods, which are referred to as the wet-dry process. The blending of recycled rubber (CRM) with asphalt has been used for years, and several manufacturing processes have been developed in Europe as well as in the USA. The use of a bituminous sub-ballast layer has been pointed out as an exciting alternative to the granular sub-ballast design traditionally applied in most railroad tracks. Frequently, unbound granular materials are replaced by bituminous sub-ballast that provide additional benefits to the subgrade protection. Much research has been conducted on finding other alternative material to be used as a modifier in asph…
Effect of the surrounding aeration on microcapillary electrochemical cell experiments
2008
In the microelectrochemical capillary cell technique a silicone rubber gasket is used to avoid any electrolyte leakage between the pulled glass capillary and the working electrode (the metallic tested material). In this study, it is demonstrated that the oxygen reduction reaction (ORR) is strongly affected by the use of the silicone rubber. Experiments under a surrounding argon gas shielding of the pulled capillary in contact with the metallic surface have been performed showing a large effect on the ORR. Considering the high permeation rate of oxygen through silicone, the decrease of the reaction rate observed experimentally was validated by FEM modelling assuming that the air/silicone/wat…