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Number of results: 7
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Abstract

It is well known that if plastic wastes are not well managed, it has a negative impact on the environment as well as on human health. In this study, recycling plastic waste in form of strips for stabilizing weak subgrade soil is proposed. For this purpose, a weak clay soil sample was mixed with 0.2%, 0.3%, and 0.4% of plastic strips by weight of soil, and the experimental results were compared to the control soil sample with 0% plastic. Laboratory tests on the Standard compaction test, Unconfined compression test (UCS), and California bearing ratio (CBR) were conducted according to the American Society for Testing and Materials (ASTM). The results of the study reveal that there are significant improvements in the strength of weak soil stabilized with plastic waste strips. Accordingly, the Standard Proctor test shows that there is a small increment in the maximum dry density of the soil when it is mixed with plastic strips. The result from the CBR test shows that there is a significant increment of CBR value with the plastic strip content. The unconfined compressive strength test also shows that increasing the percentage of plastic strips from 0 to 0.4% resulted in increased strength of soil by 138% with 2 cm length plastic strips. Therefore, this study recommends the application of plastic strips for improvement of the strength of soft clay for subgrade construction in civil engineering practice as an alternative weak soil stabilization method.
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Authors and Affiliations

Worku Firomsa Kabeta
1
ORCID: ORCID

  1. Gdansk University of Technology, Faculty of Civil and Environmental Engineering, Narutowicza11/12, 80-233 Gdansk, Poland
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Abstract

Bentonites and clays are included in the group of drilling fluids materials. The raw materials are mainly clay minerals, which are divided into several groups, like montmorillonite, kaolinite, illite, biotite, muscovite, nontronite, anorthoclase, microcline, sanidine or rutile, differing in chemical composition and crystal lattice structure. Clay minerals have a layered structure forming sheet units. The layers merge into sheets that build up to form the structure of the mineral.

The aim of the studies carried out in the ŁUKASIEWICZ Research Network - Foundry Research Institute is to explore the possibility of using minerals coming from Polish deposits.

The article outlines the basic properties of hybrid bentonites, which are a mixture of bentonite clay called beidellite, originating from overburden deposits of the Turoszów Mine, and foundry bentonite from one of the Slovak deposits. As part of the physico-chemical tests of minerals, measurements included in the PN-85/H-11003 standard, i.e. montmorillonite content, water content and swelling index, were carried out. Additionally, the loss on ignition and pH chemical reaction were determined. Based on the thermal analysis of raw materials, carried out in the temperature range from 0 to 1000oC, changes occurring in these materials during heating, i.e. thermal stability in contact with liquid metal, were determined.

Examinations of the sand mixture based on pure clay and bentonite and of the sand mixture based on hybrid bentonites enabled tracing changes in permeability, compressive strength and tensile strength in the transformation zone as well as compactability referred to the clay content in sand mixture. Selected technological and strength parameters of synthetic sands are crucial for the foundry, because they significantly affect the quality of the finished casting.

Based on the analysis of the results, the optimal composition of hybrid bentonite was selected.

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Authors and Affiliations

J. Kamińska
ORCID: ORCID
S. Puzio
ORCID: ORCID
M. Angrecki
ORCID: ORCID
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Abstract

In this work, the influence of microwave drying parameters such as irradiation time and microwave power level on the properties of synthetic moulding sands is presented. Determination of compressive strength Rc s, shear strength Rt s and permeability Ps of synthetic moulding sands with the addition of two different bentonites, after drying process with variable microwave parameters were made. The research works were carried out using the microwave oven with regulated power range of the electromagnetic field. From the results obtained, the significant influence of both drying time and microwave power level on the selected properties of moulding sands was observed. In comparison to the conventional drying method, microwave drying allows to obtain higher compressive strength of the synthetic moulding sand. The influence of application microwave irradiation on permeability was not observed. Higher strength characteristics and shorter drying time are major advantages of application of the electromagnetic irradiation for drying of the synthetic moulding sand with regard to conventional drying method.

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Authors and Affiliations

D. Nowak
B. Gal
A. Włodarska
K. Granat
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Abstract

Foundry sand waste can be utilized for the preparation of concrete as a partial replacement of sand. The strength properties of M25 grade concrete are studied with different percentages of replacement of fine aggregates by foundry sand at 0%, 10%, 20%, 30%, 40%, and 50%. The optimum percentage of foundry sand replacement in the concrete corresponding to maximum strength will be identified. Keeping this optimum percentage of foundry sand replacement as a constant, a cement replacement study with mineral admixtures such as silica fume (5%, 7.5%, 10%) and fly ash (10%, 15%, 20%,) is carried out separately. The maximum increase in strength properties as compared to conventional concrete was achieved at 40% foundry sand replacement. Test results indicated that a 40% replacement of foundry sand with silica fume showed better performance than that of fly ash. The maximum increase in strengths was observed in a mix consisting of 40% foundry sand and 10% silica fume. SEM analysis of the concrete specimens also reveals that a mix with 40% foundry sand and 10% silica fume obtained the highest strength properties compared to all other mixes due to the creation of more C-H-S gel formations and fewer pores.

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Authors and Affiliations

K.V.S. Gopala Krishna Sastry
A. Ravitheja
T. Chandra Sekhara Reddy
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Abstract

The paper presents results of measuring attenuation coefficient of the Al-20 wt.% Zn alloy (AlZn20) inoculated with different grain

refiners. During experiments the melted alloys were doped with Al-Ti3-C0.15 refining master alloy. Basing on measurements performed

by Krautkramer USLT2000 device with 1MHz ultrasound wave frequency it was stated that grain refinement reduces the attenuation

coefficient by about 20-25%. However, the examined alloys can be still classified as the high-damping ones of attenuation greater than 150

dB/m.

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Authors and Affiliations

P.K. Krajewski
W.K. Krajewski
J. Buraś
G. Piwowarski
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Abstract

The results of testing the strength properties of experimental ceramic materials containing spending moulding sand after initial mechanical reclamation as a material for subsequent layers of the stucco composition were presented. Tests were carried out on spent moulding sands from various foundry technologies, i.e. sand with furfuryl resin and sand with hydrated sodium silicate. The spent, agglomerated moulding sand has undergone a crushing process. Next, the required granular fractions used for individual layers of the stucco material were separated. Ceramic samples, in which the spent moulding sand was a substitute for fresh silica sand in successive layers of the stucco composition, were prepared. As a reference material, identical ceramic samples were used but with all layers made from the fresh silica sand. Samples prepared in this way were used to determine the bending strength of ceramic materials in the temperature range from 20 to 900ºC. The obtained values of the bending strength have demonstrated that spent moulding sand can be used in investment casting with no adverse effect on the strength of ceramic materials.

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Authors and Affiliations

M. Angrecki
ORCID: ORCID
J. Kamińska
ORCID: ORCID
J. Jakubski
ORCID: ORCID
P. Wieliczko
ORCID: ORCID

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