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Influence of steel fibres addition on mechanical and selected rheological properties of steel fibre high-strength reinforced concrete

Bywalski C., Kamiński M., Maszczak M., Balbus Ł.

Archives of Civil and Mechanical Engineering

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2015

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Vol. 15, no. 3

742--750

EN

The paper discusses the mechanical and selected rheological properties of steel fibre high-strength reinforced concrete (SFHSRC). The creep deformation in compression, total shrinkage strain, compression strength, longitudinal modulus of elasticity and tensile strength of steel fibre high-strength reinforced concrete have been presented in the research. Steel reinforcements with a length of 13 mm and a diameter of 0.2 mm have been used. The content of fibres in 1 m3 of the concrete mix was 0, 78.5, 157 and 235.5 kg. Four batches of composite materials with different mixture compositions have been tested. The average compressive strength ranged from 128.2 to 147.7 MPa. The functional relations describing the increase of shrinkage and creep deformation in time have been discussed. The summary contains conclusions related to the rheological deformation of steel fibre high-strength reinforced concrete and the effects of steel fibre content on the mechanical properties of such composite materials.

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Quartz c-axis fabrics in constrictionally strained orthogneisses: implications for the evolution of the Orlica-Śnieżnik Dome, the Sudetes, Poland

Żelaźniewicz A., Kromuszczyńska O., Biegała N.

Acta Geologica Polonica

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2013

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Vol. 63, no. 4

697--722

EN

The Orlica-Śnieżnik Dome (OSD), NE Bohemian Massif, contains in its core several gneiss variants with protoliths dated at ~500 Ma. In the western limb of the OSD, rodding augen gneisses (Spalona gneiss unit) are mainly L>S tectonites with a prominent stretching lineation. The few quartz LPO studies have produced somewhat discrepant results. Reexamination of these rocks revealed that texture formation was a protracted, multistage process that involved strain partitioning with changing strain rate and kinematics in a general shear regime at temperatures of the amphibolite facies (450–600°C). Quartz c-axis microfabrics show complex yet reproducible patterns that developed under the joint control of strain geometry and temperature; thus the LPOs are mixed features represented by pseudogirdle patterns. Domainal differences in quartz microfabrics (ribbons, tails, quartzo-feldspathic aggregate) are common in the Spalona orthogneisses but uncommon in the sheared migmatitic gneisses. In the latter rocks, the constrictional strain was imposed on the originally planar fabric defined by high-temperature migmatitic layering. The constrictional fabric of the Spalona gneisses may have developed in the hinge zones of kilometer-scale folds, where the elongation occurred parallel to the fold axes. Other occurrences of rodding gneisses throughout the Orlica-Śnieżnik Dome are thought to occupy similar structural positions, which would point to the significance of large-scale folds in the tectonic structure of the dome.

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Natlenianie zanieczyszczonych osadów dennych podczas tymczasowego składowania

Malina G., Vermeulen J., Kromer M.

Inżynieria i Ochrona Środowiska

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2004

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T. 7, nr 3/4

401-419

PL

Dla badanych osadów określono indeks dojrzewania, stopień kurczenia, współczynnik dyfuzji oraz dystrybucję tlenu. W celu odwodnienia osadów i uzyskania różnych etapów fizycznego dojrzewania osadów zastosowano potencjały matrycowe w zakresie od -100 do -1 000 000 hPa. Sprawdzono wpływ zastosowanego potencjału matrycy na występowanie miejsc pozbawionych tlenu w agregatach osadowych. Przeprowadzone badania pozwoliły na wypracowanie efektywnej metody pomiaru centrów tlenowych w osadach dennych. Dostarczyły one danych o wpływie kurczenia się agregatów na wzrost współczynnika dyfuzji tlenu, a w konsekwencji na wzrost natlenienia, co ma istotne znaczenie dla bioremediacji osadów zanieczyszczonych substancjami organicznymi (np. substancje ropopochodne, WWA) podczas ich tymczasowego składowania.

EN

Temporary disposal is the most widely adopted alternative for sediments dredged annually in some countries (e.g. the Netherlands) for both maintenance and environmental reasons. For good management of disposal sites, knowledge is required about controlling the behaviour of sediments during disposal. A short overview was made about processes that take place during temporary disposal, and how they can affect the biodegradation of organic contaminants. The method of oxygenation measurements within sediments aggregates was developed and improved in order to evaluate the bioremediation potentials during temporary disposal of sediments contaminated with organic compounds. The parameters determined for three studied sediments (I, II and III) included: the ripening index, shrinkage, diffusion coefficient and oxygen distribution in sediment aggregates. To enhance dewatering and to simulate diverse stages of sediment ripening, matrix potentials from -100 to -1,000,000 hPa were applied. The effect of diverse matrix potentials on the formation of oxic and anoxic zones within the aggregates was also determined. The complete transformation of sediments into soil was taking place at matrix potentials between -1000 and -2000 hPa when the ripening indexes for all sediments dropped below 0.7. For lower ripening indexes an increase of pore volumes filled with air was observed. The highest ripening index of 0.5 was for sediment III, in which the highest organic matter content was found. Decreasing matrix potentials resulted in an increase of the O2 penetration depths in sediment aggregates. At the matrix potential of -16,000 and lower, the whole aggregates were fully aerated. Increased organic matter contents limited the depth of O2 penetration. The diffusion coefficients were higher proportionally to the decreased matrix potentials. Shrinkage of aggregates affected the diffusion coefficients and oxygenation, which is an important factor to be considered for bioremediation of sediments contaminated with organic substances (oil hydrocarbons, PAHs) during temporary disposal. Thus, the physical ripening of dredged sediments is a promising technique to enhance aerobic bioremediation of polluted sediments.

4

Skurcz materiału roślinnego w procesie suszenia

Lewicki P., Ignaciuk E.

Inżynieria Chemiczna i Procesowa

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2004

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T. 25, z. 3/2

1261-1266

PL

Badano skurcz tkanki dyni i jabłka suszonych konwekcyjnie. Wykorzystano komputerową analizę obrazu do obserwacji zmian kształtu i wymiarów charakteryzujących materiał. Stwierdzono, że dynia ulega znacznie większemu skurczowi w czasie suszenia niż jabłko. Pole przekroju kostek zmniejszyło się o 73% w przypadku dyni i o 59% w przypadku jabłka. Jednocześnie zmniejszenie obwodu nie było proporcjonalne do zmniejszenia pola przekroju, co świadczy o silnym fałdowaniu powierzchni materiału. Pod koniec suszenia w dyni pojawiły się jamy skurczowe, gdy w jabłku zaobserwowano wystąpienie ciemnych pól na powierzchni przekroju.

EN

The aim of this work was to investigate shrinkage of pumpkin and apple cubes during convective drying. Computer image analysis was used to follow changes of shape and dimensions of the materiał during drying. Pumpkin shrinks much morę than apple and the cross-sectional area of cubes decreased by 73% and 59%, respectively. At the same time decrease of perimeter did not follow the decrease of crosssectional area. It indicates extensive folding and creasing of the surface of the cubes undergoing drying. At the finał stages of drying shrinkage cavities were formed in pumpkin cubes. In apple cubes there were no cavities observed, however dark central areas were seen.