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1.
Deformation properties and performance evaluation of reused ballast with waste tire-derived aggregates
Stanislav Lenart, Siva Ram Karumanchi, 2025, original scientific article

Abstract: The present study evaluates the shear strength characteristics, deformation properties, and degradation behavior of limestone-based reused ballast (RB) material by mixing crumbs of waste tire-derived aggregates (TDA), focusing on its suitability for railway infrastructure. Conventional large-scale direct shear tests and novel large-scale cyclic simple shear tests were performed to investigate the effects of tire-derived aggregate (TDA) content, with particle sizes varying between 22.4 mm and 50 mm. The results indicate that adding 5 % by the mass of TDA slightly reduced the friction angle from 46.6° to 44.5°, which is not a significant change compared to RB. However, increasing the TDA content to 10 % led to a notable decrease in the friction angle to 41°, highlighting the significant impact of higher TDA content on the shear strength behavior. Further, incorporating 5 % TDA improved the shear modulus and damping ratio relative to RB, which is attributed mainly to the similar larger particle sizes (22.4–50 mm) of TDA. Conversely, at 10 % TDA content, reductions in both shear modulus and damping ratio were observed. The ballast breakage index (BBI), evaluated through cyclic simple shear tests, showed a significant decrease from 15 % for RB to 9.5 % for the ballast sample containing 5 % TDA. Additionally, increased TDA content enhanced material durability, reducing Los Angeles abrasion (LAA) losses from an initial 33.5 to under 30 % at 5 % TDA. These findings demonstrate that incorporating 5 % by mass of TDA into RB material is optimal for enhancing deformation characteristics and reducing ballast degradation while maintaining adequate shear strength. This sustainable approach facilitates the recycling of waste materials, promotes a circular economy, and helps maintain safe and stable railway track conditions.
Keywords: reused ballast, rubber, cyclic simple shear tests, BBI, degradation
Published in DiRROS: 04.06.2025; Views: 577; Downloads: 339
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2.
Improved seismic response of light-frame-timber panels with cement-particle-board sheathing of various thicknesses and different configurations of fasteners
Meta Kržan, Tomaž Pazlar, Boštjan Ber, 2022, original scientific article

Abstract: Due to their comparable fire characteristics and surface preparation, light-frame timber panels using cement-particle boards (CPB) as a sheathing material present a potential alternative to gypsum-fibre boards. An experimental campaign was conducted to evaluate the behaviour of CPB light-frame-timber panels under in-plane lateral loading. Monotonic and cyclic in-plane shear tests were conducted on full-size panels, following preceding tests on the stapled sheathing-to-timber connections used in the panels. The influence of the boards’ thickness and staple geometry on the response of connections and panels was studied, also on panels with an asymmetrical CPB layout, which proved not to have a negative influence on the panels’ lateral load-bearing capacity. Furthermore, in order to improve the seismic response, panels, which had almost twice the number of staples compared to the basic panel, were tested; one variation with two rows of staples, and the other with the staples spaced closer together, such that the spacing distance was halved. The tests revealed a significant, though not proportional, increase in lateral resistance in the strengthened panels. Fastening the CPB with two rows of staples proved the better option, since subsequent failure of the CPB along the connections, as opposed to ductile failure of the staples in the basic panels, proved not to reduce the panels’ deformation capacity. The paper also compares the test results of the connections and panels to analytical results according to Eurocode 5 (EC5), the European code provision for the design of timber structures.
Keywords: light-frame timber panels, cement-particle board sheathing, cyclic shear tests, sheathing-to-timber connection, asymmetrical panel, staple spacing distance, EN 1995–1-1, open access
Published in DiRROS: 31.05.2023; Views: 1853; Downloads: 978
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