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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.

2

The impact of polypropylene fibre addition on the CBR value

Dobrzycki Patryk

Architecture Civil Engineering Environment

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2023

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Vol. 16, no. 2

81--88

EN

The classic test for soil or aggregate bearing capacity in road construction is the CBR test. The results of the CBR were determined for gravelly sand and sand with the addition of 1.5% cement, as well as for their mixtures with 18 mm long polypropylene fibres in the amounts of 0.1%, 0.2% and 0.3%. The effect of compaction and time of curing of samples stabilised with hydraulic binder were also determined. The natural soil without cement and fibre additions had relatively high CBR values. The additions of 0.1% and 0.2% polypropylene fibres to the dry mass of the soil resulted in an approximately 2-fold increase in the CBR value for the samples compacted using the standard method. Increasing the amount of fibres to 0.3% caused a reduction in the CBR value to that obtained without fibre addition. For samples compacted using the modified Proctor method, the observations are different. Only the sample with 0.2% fibre addition achieved a slightly higher CBR value. Moreover, the addition of 1.5% cement and the length of treatment increased the CBR values.

3

Wstęp redaktora naukowego wydania

Dobrzycki Patryk

Wiedza Obronna

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2020

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nr 2

5--9

4

Istota demokratycznego nadzoru i kontroli nad służbami specjalnymi

Dobrzycki Patryk

Wiedza Obronna

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2020

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nr 2

35--62

PL

Celem przedmiotowego opracowania było syntetyczne ukazanie mechanizmów nadzoru i kontroli nad służbami specjalnymi, których celem jest stworzenie właściwych warunków do bezpiecznego i skutecznego funkcjonowania służb specjalnych w porządku państwa demokratycznego. Dlatego też zakres tematyczny artykułu sprowadza się do ukazania charakteru demokratycznego nadzoru i kontroli nad służbami specjalnymi, wskazania problemów, które mają wpływ na skuteczne prowadzenie tego typu działań, wyodrębnienie typologii nadzoru i kontroli nad służbami specjalnymi oraz ich ocena w kontekście sformułowania rekomendacji, mających na celu przybliżenie najlepszych rozwiązań w przedmiotowym zakresie, które jednocześnie umożliwiają wypracowanie właściwych proporcji między efektywnością i legalnością działania służb specjalnych.

EN

The purpose of this study was to present synthetically the mechanisms of supervision and control over special services, whose purpose is to create the right conditions for the safe and effective functioning of special services in the order of a democratic state. Therefore, the thematic scope of the article boils down to showing the democratic nature of supervision and control over special services, pointing out problems that affect the effective conduct of this type of activities, identifying the typology of supervision and control over special services and their assessment in the context of formulating recommendations aimed at approximation of the best solutions in the field in question, which at the same time enable the development of the right balance between the effectiveness and legality of the secret services.