M.S.

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Environmental conditions such as temperature inevitably impact the long term performance, strength and deformation characteristics of most materials in infrastructure applications. The mechanical and durability properties of geosynthetic materials are strongly temperature dependent. The interfaces between geotextiles and geomembranes as well as between granular materials such as sands and geomembranes in landfill applications are subject to temperature changes due to seasonal temperature variations as well as exothermic reactions occurring in the waste body. This can be a critical factor governing the stability of modern waste containment lining systems. Historically, most laboratory geosynthetic interface testing has been performed at room temperature. Information today is emerging that shows how temperatures in the liner systems of landfills can be much higher. An extensive research study was undertaken in an effort to investigate temperature effects on interface shear behavior between (a) NPNW polypropylene geotextiles and both smooth PVC as well as smooth and textured HDPE geomembranes and (b) sands of different angularity and smooth PVC and HDPE geomembranes. A temperature controlled chamber was designed and developed to simulate elevated temperature field conditions and shear displacement-failure mechanisms at these higher temperatures. The physical laboratory testing program consisted of multiple series of interface shear tests between material combinations found in landfill applications under a range of normal stress levels from 10 to 400 kPa and at a range of test temperatures from 20 to 50 °C. Complementary geotextile single filament tensile tests were performed at different temperatures using a dynamic thermo-mechanical analyzer (DMA) to evaluate tensile strength properties of geotextile single filaments at elevated temperatures. The single filament studies are important since the interface strength between geotextiles and geomembranes is controlled by the fabric global matrix properties as well as the micro-scale characteristics of the geotextile and how it interacts with the geomembrane macro-topography. The peak interface strength for sand-geomembrane as well as geotextile-geomembrane interfaces depends on the geomembrane properties such as hardness and micro texture. To this end, the surface hardness of smooth HDPE and PVC geomembrane samples was measured at different temperatures in the temperature controlled chamber to evaluate how temperature changes affect the interface shear behavior and strength of geomembranes in combination with granular materials and/or geotextiles. The focus of this portion of the experimental work was to examine: i) the change in geomembrane hardness with temperature; ii) develop empirical relationships to predict shear strength properties of sand - geomembrane interfaces as a function of temperature; and iii) compare the results of empirically predicted frictional shear strength properties with the results of direct measurements from the interface shear tests performed at different elevated temperatures.

Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Geotextiles perform a number of functions in various applications in civil engineering practise. It is often cost effective and more environmentally friendly versus conventional construction methods. One of the main functions of a geotextile is filtration whereby the geotextile is expected to hold back the soil particles and simultaneously has to allow sufficient water to pass through it. Soils are all different and can be problematic when it comes to designing geotextile filters. One such problematic soil is encountered in KwaZulu- Natal, situated along the east coast of South Africa. The Berea sand is problematic as it can highly variable in its engineering properties over a small area. Geotextiles are becoming more and more common practice in South Africa and little is known about the filtration performance of commercially available geotextiles in conjunction with Berea sand. Local guidelines that are available are out of date and do not provide enough information to assist design engineers in decision making. Many international guidelines are available and it is difficult to choose which one is best suited to Berea sands. This primary objective of this study is to investigate the filtration performance of four variants of commercially available geotextiles and three variants of Berea sand. The applicability of some of the international filter design criteria will also be assessed. The soil to geotextile compatibility testing was carried out as per ASTM D5101 (2006) - Standard Test Method for Measuring the Soil-Geotextile System Clogging Potential by the Gradient Ratio. In total 12 permutations were executed. The results showed that only 5 test permutations met the gradient ratio and permeability criteria. The test results also conclude that the permeability is just as important as the gradient ratio. Thick geotextiles should be considered when used as filters in Berea sands. The available international geotextile filter design criteria were assessed and all showed poor correlation between laboratory results and suggested criteria. Designing geotextile filters in conjunction with Berea reds is challenging and it is recommended that design engineers perform laboratory performance testing in conjunction with their designs. / AFRIKAANSE OPSOMMING: Geotekstiele verrig vir 'n aantal funksies in verskeie programme in die siviele ingenieurswese praktyk. Dit is dikwels meer koste-effektief en omgewingsvriendelik, teenoor konvensionele konstruksie metodes. Een van die belangrikste funksies van 'n geotekstiel is filtrasie, waardeur van die geotekstiel verwag word om van die grond terug te hou, en gelyktydig genoeg water daardeur te laat vloei. Grond verskil en dit kan problematies wees wanneer dit kom by die ontwerp van geotekstiel filters. Een so ‘n problematiese grond kom voor in KwaZulu-Natal, geleë langs die ooskus van Suid-Afrika. (Die) Berea sand is problematies, want dit verander geweldig baie ten opsigte van ingenieurseienskappe oor 'n redelike klein area. Gebruik van geotekstiele word al hoe meer ‘n algemene praktyk in Suid- Afrika, terwyl min bekend is oor die filtrasie prestasie van kommersieel beskikbare geotekstiele in samewerking met Berea sand. Plaaslike riglyne wat beskikbaar is, is verouderd en onvoldoende inligting is beskikbaar aan ontwerpingenieurs vir besluitneming . Baie internasionale riglyne is beskikbaar en dit is moeilik om te besluit watter een die beste van toepassing is vir Berea sand. Die doel van hierdie studie is om die filtrasie prestasie van vier modelle van kommersieël beskikbare geotekstiele en voorbeelde van drie soorte Berea sand te ondersoek. Die toepaslikheid van 'n paar van die internasionale filter ontwerp kriteria sal ook beoordeel word. Die toetsing van grondverenigbaarheid met geotekstiel is uitgevoer soos aangedui in ASTM D5101 (2006 ) – Standaard Toets Metode vir die meet van die grond-Geotekstiel verstopping potensiëel deur die gradient verhouding. In totaal is 12 permutasies uitgevoer. Die resultate het getoon dat slegs 5 toetspermutasies beide gradiënt verhouding en permeabiliteit kriteria bevredig het. Dikker geotekstiele word ook aanbeveel vir gebruik as filters in Berea sand. Van die toets resultate kan ook afgelei word dat die permeabiliteit net so belangrik soos die gradiënt verhouding is. Beskikbare internasionalegeotekstiel filter ontwerp kriteria is nagegaan en al die metodes het swak korrelasie tussen laboratorium resultate en die voorgestelde kriteria getoon. Om geotekstiel filters in samewerking met Berea Reds te ontwerp is 'n uitdaging en dit word aanbeveel dat ontwerpingenieurs laboratorium prestasietoetsing in samewerking met hul ontwerpe uitvoer.

Os geotêxteis não-tecidos desempenham, dentre outras funções, papel relevante na filtração e drenagem de solos. Nesta função, necessitam ter vazios suficientemente grandes para permitir a livre passagem de água e, ao mesmo tempo, vazios suficientemente pequenos para impedir o arraste de partículas, de sorte a evitar a erosão interna do solo. Critérios de dimensionamento para atender a ambos os requisitos estão disponíveis na literatura e são utilizados com sucesso há vários anos. Uma situação menos estudada e compreendida refere-se ao desempenho desses geotêxteis na filtração de água com sólidos em suspensão. Trata-se de uma situação tida como crítica, pela possibilidade de colmatação do geotêxtil por essas partículas, de acordo com diferentes mecanismos. Neste trabalho, verifica-se o desempenho, em laboratório, de geotêxteis não-tecidos frente à filtração de suspensões de solo em água, tal qual poderia ocorrer por ocasião de enxurradas. Nessa perspectiva, tenta-se verificar qual poderia ser o desempenho desses geotêxteis quando utilizados para compor sistemas de proteção da entrada de estruturas de captação de água, como bocas de lobo e bueiros. O trabalho utiliza um geotêxtil não tecido de fibras curtas, fabricado a partir de poliéster e suspensões contendo bentonita e uma areia fina argilosa, solo típico da região de São Carlos, em diferentes concentrações. Estabelecem-se correlações entre diferentes características e propriedades dos geotêxteis estudados e estuda-se o mecanismo de colmatação, que em geral ocorreu para todos os geotêxteis, em intervalos de tempo associados às características do geotêxtil e à concentração de solo na suspensão. As severas condições de colmatação observadas e o comprometimento da permeabilidade dos geotêxteis sugerem que para as concentrações de solo utilizadas, os geotêxteis não seriam capazes de cumprir com a proteção da entrada de estruturas de drenagem. / Nonwoven geotextiles play an important role in filtration and drainage of soils, among other functions. In these functions, they need to have large enough internal voids to allow free passage of water and at the same time these voids should be small enough to prevent the passing of particles and preventing piping formation or erosion of soil. Design criteria to satisfy both requirements are available in the literature and have been used successfully for many years. A topic that has not been deeply addressed refers to the performance of geotextiles on filtration of water with suspended solids since the possibility of geotextile clogging is real, impairing its behavior. In this work, the performance of nonwoven geotextiles in laboratory tests designed to observe the filtration of water containing solid particles in suspension is addressed. The tests were devised trying to understand what could be the performance of these geotextiles when used to compose inlet protection systems for drainage structures, such as culverts. The study used nonwoven short-fibers geotextile, made of polyester and suspensions containing bentonite and clayey fine sand, a typical soil of São Carlos area, Brazil, in different concentrations. The laboratory test results show that there exist correlations among different characteristics and properties of geotextiles studied and allowed to evaluate the mechanism of clogging, which generally occurred for all geotextiles, in time intervals associated to some characteristics of the geotextile and to the soil concentration in suspension. The severe clogging observed and the reduction of permeability of geotextile suggest that, for the solids concentration used, the geotextiles could not protect the entrance of drainage structures.

O uso de geossintéticos em rodovias tem recebido considerável atenção nas últimas décadas. A utilização de materiais alternativos na reabilitação de pavimentos flexíveis, utilizando sistemas anti-reflexão de trincas, tem se destacado entre pesquisas acerca deste tema. A experiência internacional mostra que o uso de geotêxteis não tecidos, aliados ao ligante asfáltico, tem demonstrado bom desempenho em obras de restauração de pavimentos. No entanto, o sucesso desta técnica depende diretamente do entendimento do comportamento dos geotêxteis quando impregnados com asfalto. Neste contexto, este estudo avaliou diferentes geotêxteis não tecidos frequentemente utilizados em sistemas anti-reflexão de trincas, enfatizando o ganho de rigidez à tração e a redução da permeabilidade destes materiais após a impregnação com o ligante asfáltico. Amostras de geotêxteis não tecidos de poliéster e polipropileno foram impregnadas com emulsão asfáltica catiônica de ruptura rápida. Ensaios de tração foram realizados de acordo com a ABNT - NBR 12824/93 e os ensaios de transmissão de vapor d\'água foram conduzidos conforme as especificações da ASTM - E96M/05. Os resultados dos ensaios de tração em geotêxteis impregnados mostraram um aumento significativo dos valores de rigidez à tração para os níveis de deformação analisados. Resultados revelaram também um elevado aumento nos valores de rigidez à tração para níveis de deformação da ordem de 0,03%. Ensaios de transmissão de vapor d\'água demonstraram que a emulsão asfáltica aplicada sobre os geotêxteis permite uma drástica redução nos valores de permeabilidade normal do material, podendo transformar este sistema em uma barreira impermeável. / The use of geosynthetics in roadway systems has received considerable attention over the past decades. Paving fabrics have been used for rehabilitation of pavements to reduce propagation of cracks and to extend pavement life. In addition, the success of this technique depends directly on the understanding of the geotextiles behavior when impregnated with asphalt. I this sense, this study evaluated different nonwoven geotextiles frequently used in the anti-reflective cracking systems, focusing on initial stiffness gain and permeability reduction. Virgin and impregnated specimens of polyester and polypropylene nonwoven geotextiles were used. Cationic rapid setting emulsified asphalt (CRS) was used as asphalt binder. Wide-width tensile tests were performed in accordance with ABNT - NBR 12824/93 and water vapor transmission tests (WVT) were performed according to ASTM E96M/05. The results of tensile tests on impregnated geotextiles showed significantly increase in tensile stiffness values. Results also showed high increase in stiffness values at strain levels less than 0.03% and decrease on stiffness gains with the increase of strains. Water vapor transmission tests demonstrated that cationic asphalt emulsion applied on nonwoven geotextiles allows a drastic reduction in permeability values and may turn this system in a low permeability barrier.

The purpose of the study was to assess county extension agents' knowledge of geotextiles; to determine their current level of information and their location on an adoption-diffusion curve; and to determine the agents' attitudes toward the potential use of geotextiles in agriculture, specifically in soil erosion control. A questionnaire was designed to investigate the extension agents' basic knowledge of geotextiles and current uses; and through a self-rating selection, to determine their position on an adoption-diffusion curve. The 30- item questionnaire also incorporated measures determining the agents' attitude toward, and perception of potential for, geotextile use in agricultural practices. The questionnaire was mailed to all 122 county extension agricultural, horticultural, and farm management agents in Oregon and Idaho. A total of 92 usable replies (75.4%) were received and included in the study. Descriptive statistics were employed in the analysis of the individual questions and the chi-square test was used in the analysis of nominal data for all hypotheses. The level of significance was set at .05. The development of a profile of the agents' knowledge of basic geotextile functions showed the agents were most familiar with landscape fabric; they were first introduced to the fabrics through commercial literature and extension agents/specialists; and they were first made aware 2-5 years ago. The most important project which used a geotextile in the agent's county(ies) was most frequently designed and installed by a farmer or rancher, in use less than five years, and increased productivity immediately or within one growing season. A significant relationship was found to exist between the agents' self-rating of their level of knowledge and their area of expertise. The horticultural agents' self-rating of their level of knowledge of agro-textiles was most often cited as "moderate." The crops and combination agents claimed to have "very little" knowledge and the livestock agents said "very little" or "none." Significant relationships could not be established between the agents' self-rating of their level of knowledge and the most prevalent farm or ranch land use in their county; their length of employment; and their attitude toward, or perception of, geotextile use in agricultural practices. No significant relationship could be confirmed between the curve created by the agents' knowledge and Rogers' (1958, p. 351) adoption-diffusion curve. Because agro-textiles are a relatively new product, complete adoption has not yet taken place. Therefore, the agents' curve is not expected to be normal. Results showed the major benefits in using agro-textiles were "increased productivity" and "dollars saved." Other benefits included: the savings of water and time; and the control of frost and increased soil warmth, which led to earlier harvests, longer seasons, and less loss of crops. The real and/or perceived barriers against the use of agro-textiles most cited were "too expensive" and "not cost effective." / Graduation date: 1993

Baigiamajame magistro darbe nagrinėtas armuotų šlaitų pastovumą užtikrinančių geosintetinių gaminių kiekis ir stipris parenkant užpildą bei keičiant šlaito kampą. Siekiant padidinti šlaito pastovumą, nagrinėti tokie skaičiavimo atvejai: pirmas – kai šlaito užpildą sudaro birūs gruntai, kurių vidinės trinties kampas kinta φ = 38˚ ÷ 27˚, sankabumas c ir vienetinis grunto svoris γ pastovus; antras – kai vidinės trinties kampas kinta φ=38˚÷27˚, vienetinis grunto svoris kinta γ = 19,8 ÷ 15,1 [kN/m3], o sankabumas c pastovus; trečias – kai kinta sankabumas c = 10 ÷ 30 [kPa], o vidinės trinties kampas φ ir vienetinis grunto svoris γ pastovus; ketvirtas – kai kinta šlaito posvyrio kampas nuo 63° iki 45˚. Armuoti šlaitai sumodeliuoti ir paskaičiuoti „Stability“ programa, išnagrinėjus rezultatus, pateikiamos baigiamojo darbo išvados. / In the master thesis it was analysed of reinforcement slopes stability controlled reduce the slope angle, change of fill properties. To increase the slope stability, consideration of such cases in the calculation: first – properties of fill: angle of friction change φ = 38˚ ÷ 27˚, cohesion c and unit weight of the soil γ are constant; second – properties of fill: angle of friction change φ = 38˚ ÷ 27˚, unit weight of the soil change γ = 19,8 ÷ 15,1 [kN/m3], cohesion c is constant; third – cohesion change c = 10 ÷ 30 [kPa], angle of friction φ and unit weight of the soil γ are constant; fourth – reduce the slope angle from 63° to 45˚. „Huesker – Stability „ program were used for calculation and design. After analysis of results, there were formulated an conclusion.

Thesis (Ph.D.) -- University of Western Sydney, Nepean, 2001. / A thesis submitted for the degree of Doctor of Philosophy, School of Civic Engineering and Environment, University of Western Sydney, Nepean, January, 2001. Bibliography : p. 215-225.

O uso de geossintéticos em rodovias tem recebido considerável atenção nas últimas décadas. A utilização de materiais alternativos na reabilitação de pavimentos flexíveis, utilizando sistemas anti-reflexão de trincas, tem se destacado entre pesquisas acerca deste tema. A experiência internacional mostra que o uso de geotêxteis não tecidos, aliados ao ligante asfáltico, tem demonstrado bom desempenho em obras de restauração de pavimentos. No entanto, o sucesso desta técnica depende diretamente do entendimento do comportamento dos geotêxteis quando impregnados com asfalto. Neste contexto, este estudo avaliou diferentes geotêxteis não tecidos frequentemente utilizados em sistemas anti-reflexão de trincas, enfatizando o ganho de rigidez à tração e a redução da permeabilidade destes materiais após a impregnação com o ligante asfáltico. Amostras de geotêxteis não tecidos de poliéster e polipropileno foram impregnadas com emulsão asfáltica catiônica de ruptura rápida. Ensaios de tração foram realizados de acordo com a ABNT - NBR 12824/93 e os ensaios de transmissão de vapor d\'água foram conduzidos conforme as especificações da ASTM - E96M/05. Os resultados dos ensaios de tração em geotêxteis impregnados mostraram um aumento significativo dos valores de rigidez à tração para os níveis de deformação analisados. Resultados revelaram também um elevado aumento nos valores de rigidez à tração para níveis de deformação da ordem de 0,03%. Ensaios de transmissão de vapor d\'água demonstraram que a emulsão asfáltica aplicada sobre os geotêxteis permite uma drástica redução nos valores de permeabilidade normal do material, podendo transformar este sistema em uma barreira impermeável. / The use of geosynthetics in roadway systems has received considerable attention over the past decades. Paving fabrics have been used for rehabilitation of pavements to reduce propagation of cracks and to extend pavement life. In addition, the success of this technique depends directly on the understanding of the geotextiles behavior when impregnated with asphalt. I this sense, this study evaluated different nonwoven geotextiles frequently used in the anti-reflective cracking systems, focusing on initial stiffness gain and permeability reduction. Virgin and impregnated specimens of polyester and polypropylene nonwoven geotextiles were used. Cationic rapid setting emulsified asphalt (CRS) was used as asphalt binder. Wide-width tensile tests were performed in accordance with ABNT - NBR 12824/93 and water vapor transmission tests (WVT) were performed according to ASTM E96M/05. The results of tensile tests on impregnated geotextiles showed significantly increase in tensile stiffness values. Results also showed high increase in stiffness values at strain levels less than 0.03% and decrease on stiffness gains with the increase of strains. Water vapor transmission tests demonstrated that cationic asphalt emulsion applied on nonwoven geotextiles allows a drastic reduction in permeability values and may turn this system in a low permeability barrier.