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Effect of the Addition of Dispersed Reinforcement on the Resilient Modulus of Slightly Cemented Non-Cohesive Soil

Wasil Mariola, Dobrzycki Patryk, Zabielska-Adamska Katarzyna

Studia Geotechnica et Mechanica

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2023

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Vol. 45, nr s1

293--303

EN

The aim of this article is to determine the effect of the addition of dispersed reinforcement on the resilient modulus of non-cohesive soil used as material for improved subgrade or subbase course of the pavement structure. Resilient modulus (Mr) is a parameter used in road construction, which characterises soil subgrade or base aggregates stiffness in flexible pavement subjected to the traffic load. This article presents laboratory test results of non-cohesive coarse material (gravelly sand – grSa – without fines) with the addition of 1.5% cement and dispersed reinforcement – polypropylene fibres in lengths of 12, 18 and 40 mm. Tests were conducted on the samples with various percentages of fibres (0, 0.2 and 0.3%) relating to the dry mass of the soil. Samples were compacted according to the standard Proctor (SP) and modified Proctor (MP) methods. Main laboratory tests were conducted in the triaxial apparatus enabling testing samples subjected to cyclic loads according to AASHTO T307 standard. Resilient modulus was determined after 7 and 28 days of curing. The results indicate the influence of fibre amount, fibre length, and curing time on the Mr of the soil modified with 1.5% of cement. The obtained results were also influenced by the method of compaction. The addition of polypropylene fibres decreases the resilient modulus of soil stabilised by 1.5% of cement. The best results of dispersive reinforcement were obtained for samples containing 0.3% of fibres with a length of 18 mm, compacted by the MP methods.

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Effect of ureolytic bacteria on compressibility of the soils with variable gradation

Wasil Mariola, Wydro Urszula, Wołejko Elżbieta

Architecture Civil Engineering Environment

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2023

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Vol. 16, no. 3

131--139

EN

The aim of this study is to present the effect of treatment with ureolytic bacteria (Sporosarcina pasteurii) on the compressibility parameters of mineral and anthropogenic soils. In the presence of the urease enzyme, secreted by a strain of Sporosarcina pasteurii bacteria, urea hydrolysis occurs, allowing CaCO3 to be precipitated. The literature suggests applying the Microbially Induced Calcite Precipitation (MICP) method to non-cohesive soils. In order to determine whether the biomineralization process occurs in other soil types, cohesive and anthropogenic soils were tested in the laboratory. Compressibility tests were carried out in the laboratory on MICP-treated and untreated soils as reference samples. The process of biocementation in the soil is made possible by the introduction of bacteria into the soil and subsequent activation by a cementation solution (consisting of urea and calcium ions Ca2+). This paper presents the methodology for introducing bacteria into the soil, as well as the effect of the biomineralization process on the deformation parameters of the tested materials.

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Wpływ dodatku bentonitu na właściwości uszczelniające popiołu lotnego

Wasil Mariola

Materiały Budowlane

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2019

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nr 5

56--57

PL

W przypadku doboru materiału do budowy warstwy uszczelniającej niezbędne jest określenie jego współczynnika filtracji. Badania przewodności hydraulicznej przeprowadzono dla popiołu lotnego oraz popiołu lotnego z dodatkiem 5, 10 lub 15% bentonitu. Próbki badano w warunkach niemożliwej bocznej rozszerzalności przy użyciu konsolidometru typu Rowe’a-Bardena. Zaobserwowano wpływ dodatku bentonitu na zmniejszenie wartości przewodności hydraulicznej badanych mieszanin. Otrzymane z badań wartości współczynnika filtracji wskazują, że badane materiały mogą być stosowane do wbudowywania w warstwy uszczelniające składowisk odpadów.

EN

In process of choosing material to be built in sealing layer it is necessary to obtain its hydraulic conductivity. Laboratory tests of hydraulic conductivity were conducted on fly ash and fly ash with 5, 10 or 15% of bentonite addition. The samples were tested in the Rowe-Barden consolidometer. It was observed, that bentonite addition has influence on the decrease of the hydraulic conductivity of tested mixtures. The obtained results show that tested materials are accurate to be built in landfill sealing layers.