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The effective parameters on the behaviour of treated sands by microbial-induced calcite precipitation under undrained triaxial test

Ekramirad Seyed Abdollah, Azadi Mohammad, Shamskia Nasser

Archives of Mining Sciences

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2023

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Vol. 68, no. 1

55--69

EN

Nowadays, geotechnical specialists are focused on reinforcing soil engineering parameters using innovative and environmentally friendly methods. Microbial-Induced Calcite Precipitation is a ground improvement method for modifying soil strength, permeability, and stiffness; therefore, it can be vital to study the effective factors on the technique’s efficiency and cost reduction. This study examined how biologically treated sands subjected to undrained triaxial loading responded to simultaneous changes in cementation solution molarity, optical density (OD600), and curing time. The triaxial experiments showed that the strength increased with the rise in the mentioned parameters. While the solution molarity and optical density had the highest and lowest effect on the soil improvement process, respectively, the optical density role was considerably low when the molarity was high. Increasing the molarity of the cementation solution resulted in a 45% increase in the peak stress ratio, while the optical density and curing time were constant. On the other hand, similar behaviour of dense sand and change in the response of cemented soil from strain-hardening to strain-softening were other notable observations of this study. In addition, the peak stress ratio at low strains increased with increasing the cementation level and then decreased to close to the amount of untreated sand with increasing strain.

2

Effect of parameters of the stereolithography process on the part quality

Lewiński Tomasz, Kukiełka Krzysztof, Chaciński Tomasz, Jaskólski Piotr

Journal of Mechanical and Energy Engineering

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2022

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Vol. 6, No 2

1--12

EN

This paper investigates the effect of additive manufacturing parameters on the manufacturing quality of selected gear mechanism components. Three input variables, and two output variables were determined. The result was the determination of the most optimal combination of key parameters and the determination of regression equations. The concept of manufacturing objects of a very complex shape, by any person, under various conditions through the use of a low-cost device became the basis for this thesis topic. Curing time, layer thickness, and lift speed are among the basic parameters, with a large range of manipulation. A hypothesis was formulated that these three parameters are crucial to produce a part with the smallest possible deviations from the computer model. A handheld scanner was used to scan the samples and compare them with the CAD model. Based on the study, optimal parameters for layer thickness, curing time and lift speed were proposed.

3

Effects of crumb rubber on compressive strength of cement-treated soil

Wang F. C., Song W.

Archives of Civil Engineering

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2015

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Vol. 61, nr 4

59--78

EN

A study was undertaken to investigate the effects of crumb rubber on the strength and mechanical behaviour of Rubberized cement soil (RCS). In the present investigation, 26 groups of soil samples were prepared at five different percentages of crumb rubber content, four different percentages of cement content and two different finenesses of crumb rubber particle. Compressive strength tests were carried out at the curing age of 7 days, 14 days, 28 days and 90 days. The test results indicated that the inclusion of crumb rubber within cement soil leads to a decrease in the compressive strength and stiffness and improves the cement soil’s brittle behaviour to a more ductile one. A reduction of up to 31% in the compressive strength happened in the 20% crumb content group. The compressive strength increases with the increase in the cement content. And the enlargement of cement content is more efficient at low cement content.

PL

Celem raportu jest przedstawienie wpływu granulowanych odpadów gumowych na wytrzymałość i mechaniczne zachowanie gumowanej mieszanki cementu i gruntu (Rubberized Cement Soil, RCS). W ostatnich dekadach wzrosło znaczenie obróbki gruntu z użyciem cementu w celu poprawy problematycznych gruntów. Kilku badaczy zmieszało różne wybrane dodatki z gruntami sztucznie cementowanymi. Ale warto zauważyć, że dodatki czasami prowadzą do wysokiej sztywności i kruchości. Ponadto problem związany z środowiskiem naturalnym jest coraz gorszy, a brak zasobów jest coraz bardziej dokuczliwy. Zastosowanie recyklingu opon gumowych w gruncie stabilizowanym cementem może być skutecznym sposobem wykorzystania gumy i rozwiązaniem problemu wysokiej sztywności i kruchości gruntów sztucznie cementowanych. Dodanie granulowanych odpadów gumowych powoduje znaczne zmniejszenie wytrzymałości oraz sztywności betonu.

4

1-propenyl ethers of butanediol as effective modifiers of UV-cured epoxy coatings in cationic polymerization

Martysz D., Urbala M., Antoszczyszyn M., Pilawka R.

Polimery

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2002

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T. 47, nr 11-12

849-851

EN

Models mono- and di-1-propenyl butane-1,4-diol ethers (MoPnE and DiPnE respectively) have been used as modifiers of coatings on the basis of epoxy resin Epidian 6, UV-cured at room temperature in the presence of air and cationic initiators (triarylsulfonium salts containing either SbF6- or PF6- anions). The effects of the type and amount of the ether used as a modifier as well as curing time on glass transition temperature, flexibility hardness and drying time of coatings investigated have been determined. MoPnE appeared to be most reactive modifier because of the presence of two reactive points in the molecule: double bond and primary OH group. This ether can be included into a new class of the monomers active in cationic polymerization of so called monofers.

PL

Zastosowano modelowe etery mono- i di-1-propenylowe 1,4--butanodiolu (odpowiednio MoPnE i DiPnE) jako modyfikatory powłok na podstawie żywicy epoksydowej "Epidian 6", utwardzanych w temperaturze pokojowej w atmosferze powietrza promieniowaniem UV w obecności inicjatorów kationowych (soli triarylosulfoniowych, zawierających aniony SbF6~ lub PF6~). Określono wpływ rodzaju i ilości eteru użytego jako modyfikator oraz czasu naświetlania na temperaturę zeszklenia, elastyczność, twardość oraz czas wysychania badanych powłok (rys. 1 i 2 , tabele 1 i 2). Bardziej reaktywnym modyfikatorem okazał się MoPnE, co wynika z obecności w jego cząsteczce dwóch grup funkcyjnych: wiązania podwójnego i pierwszorzędowej grupy hydroksylowej. Eter ten można zaliczyć do nowej klasy monomerów aktywnych w polimeryzacji kationowej - tzw. monoferów.