<abstract xmlns="http://www.w3.org/1999/xhtml">In the process of preparing cement or asphalt concrete – frequently used in ways, roads and access road construction, it is necessary to sort out poly-dispersed granular mixtures from bilge deposits or quarries. The mechanical sieving performs the separation of the granules on dimensional sorts (the size of graded grains can be 1... 70 mm) by means of machines called screeners. In the case of vibrating screeners, the working body (the sieve) presents a vibratory movement that ensures a high productivity of the screening machine and a very good quality of the final products obtained. The article studies the productivity of the vibrating screen used in mineral aggregates sorting process obtained by different methods. In this regard, a pragmatic simplified formula called Pragma is proposed, a formula which was tested with good results in situ experiments done on a bi-mass vibrating screen in a pilot station.</abstract>

Technical University of Civil Engineering

Vice-Rector of Technical University of Civil Engineering

Mechanical Department of Faculty of Technological Equipment

Innovative Calculation Method of the Productivity of Vibrating Screens Used in Mineral Aggregates Sorting

<abstract xmlns="http://www.w3.org/1999/xhtml">The use of crumb rubber in the modification of asphalt has occurred because of the problems related to disposal of scrap tires. However, the use of scrap tires in asphalt pavements, known as asphalt rubber pavements, can minimize environmental impacts and maximize conservation of natural resources. The textile fibers from recycled tires are typically disposed of in landfills or used in energetic valorization, but similar to other fibers, they can be used as a valuable resource in the reinforcement of engineering materials such as asphalt mixtures. Thus, this work aims at studying the use of textile fibers recycled from ground tires in the reinforcement of conventional asphalt mixtures. The application of textile fibers from ground tires was evaluated through laboratory tests on specimens extracted from slabs produced in the laboratory. Indirect tensile tests were performed on a series of nine asphalt mixtures with different fiber and asphalt contents and compared with a conventional mixture. The results obtained from a 50/70 pen asphalt were used to define three asphalt mixture configurations to be used with 35/50 pen asphalt. The results indicate that the textile fibers recycled from used tires can be a valuable resource in the reinforcement of asphalt mixtures.</abstract>

C-TAC – Territory, Environment and Construction Centre

Instituto Mauá de Tecnologia, São Caetano do Sul

Nottingham Transportation Engineering Centre

Preliminary Studies to Use Textile Fibers Obtained from Recycled Tires to Reinforce Asphalt Mixtures

<abstract xmlns="http://www.w3.org/1999/xhtml">The rail dampers are mechanical devices which work as dynamic absorbers to reduce the rail vibration and rolling noise. The paper shows the experimental results from the functionality and performance testing of an experimental demonstrative rail damper. The vibration attenuation takes the highest values, namely 6-22 dB, between 160 and 1000 Hz.</abstract>

Testing the Functionality and Performance of a Rail Damper

<abstract xmlns="http://www.w3.org/1999/xhtml">The paper focuses on the experimental verification of the results derived from numerical simulations, based on a model of the bogie-track system, where the vertical track irregularities are introduced in the form of a pseudorandom function. This function comes from an original method of synthesizing the vertical track irregularities, depending on the geometric quality of the track and on the velocity. To verify the method, the root mean square (RMS) of the simulated accelerations in the axles and the bogie frame against each axle is compared to the experimental accelerations within the frequency range of wavelengths of the track vertical irregularities from 3 to 120 m. The results have shown a good correlation between the simulated RMS accelerations for a low quality track and the measured RMS accelerations.</abstract>

Experimental Verification of Method to Synthesize the Track Vertical Irregularities

<abstract xmlns="http://www.w3.org/1999/xhtml">The paper aims to identify possible methods for balancing the allocation of transport flow on modal subsystems in order to efficiently use the infrastructures and reduce the negative effects of today’s unbalance. The aspects of intermodal competition are reviewed, considering the economic concepts regarding the substitutability of transportation services, conformation degree to the perfect competition model and the nature of cross elasticity demand.A top-down analysis over the whole infrastructure assembly is performed. The results, under the presumption of valid work hypothesis, indicated that for further analysis the set of networks transferring material flows can be assumed as disconnected from the other networks sets transferring energy, informational and values flows.The second part of the paper develops, for that disconnected networks, a generalized cost optimization model for multimodal transportation, where the comfort and safety are accounted. Thus, the performance of the existing algorithms based only on trip length, trip duration and energy consumption can be significantly improved. Additionally, the author proposes three new independent types of modal analysis that allow end-users and companies involved in transport organization to optimize their modal choice and the whole transport process organization.</abstract>

Modal Competition and Complementarity: Cost Optimization at End-User Level

<abstract xmlns="http://www.w3.org/1999/xhtml">For new railway bridges with small spans (L ≤ 35.00 m) superstructures with steel beams embedded in concrete are recommended and used, which can ensure the requirements of strength and especially stiffness, regardless of velocity.In all the design prescriptions used so far for superstructures with steel beams embedded in concrete, and even in the technical literature, there is little information and data on the influence of the support line obliquity and the track axis curvature in the design and calculation of these types of structures.In the design code, if certain conditions related to the geometry of the superstructure are met (obliquity, curvature) the calculation is a simplified one, made on a single isolated longitudinal beam of the deck; otherwise, if the conditions are not met, finite element program analysis is recommended.The article aims to study the situations in which the requirements of the design prescriptions are not met.</abstract>

Simultaneous Influence of the Track Axis Curvature and the Support Line Obliquity at Railway Bridge Superstructures with Steel Beams Embedded in Concrete

AHEAD OF PRINT

Volume 12 (2023): Issue 2 (December 2023)

Volume 12 (2023): Issue 1 (July 2023)

Volume 11 (2022): Issue 2 (December 2022)

Volume 11 (2022): Issue 1 (July 2022)

Volume 10 (2021): Issue 2 (December 2021)

Volume 10 (2021): Issue 1 (July 2021)

Volume 9 (2020): Issue 2 (December 2020)

Volume 9 (2020): Issue 1 (July 2020)

Volume 8 (2019): Issue 2 (December 2019)

Volume 8 (2019): Issue 1 (July 2019)

Volume 7 (2018): Issue 2 (December 2018)

Volume 7 (2018): Issue 1 (July 2018)

Volume 6 (2017): Issue 2 (December 2017)

Volume 6 (2017): Issue 1 (July 2017)

Volume 5 (2016): Issue 2 (December 2016)

Volume 5 (2016): Issue 1 (July 2016)

Volume 4 (2015): Issue 2 (December 2015)

Volume 4 (2015): Issue 1 (July 2015)

Volume 3 (2014): Issue 2 (December 2014)

Volume 3 (2014): Issue 1 (July 2014)

Volume 2 (2013): Issue 2 (December 2013)

Volume 2 (2013): Issue 1 (July 2013)

Volume 1 (2012): Issue 1 (December 2012)

Romanian Journal of Transport Infrastructure

Through its appearance (twice per year) magazine aims to be a high-quality scientific source of information for researchers, academics, engineers, practitioners, policy – makers, PhDs, students and anyone interested in various issues related to transport infrastructure: roads, bridges, railways and geotechnics.  The aim of the journal is to reflect the results of fundamental and applied research at a high level, maintained through a rigorous peer review performed by specialists, well known in the field, both at national and international level.  Romanian Journal of Transport Infrastructure (RJTI) involves the design, manufacture and maintenance of all categories of roads, airports, bridges, railways, tunnels and all types of transportation mean. The journal deals also with the materials and technologies in transport infrastructure and transportation engineering.  Welcome to receive original research papers involving latest discoveries and improvements in this area.  Archiving  Sciendo archives the contents of this journal in Portico - digital long-term preservation service of scholarly books, journals and collections.  Plagiarism Policy  The editorial board is participating in a growing community of Similarity Check System's users in order to ensure that the content published is original and trustworthy. Similarity Check is a medium that allows for comprehensive manuscripts screening, aimed to eliminate plagiarism and provide a high standard and quality peer-review process. 