<p>Cover crop use, especially in no-till systems, is an evolving practice to maintain or improve soil health. There are many possible indicators of soil health, but this study focuses on the analysis of soil aggregate stability, soil active carbon, and soil organic matter. Soil aggregate stability is related to water infiltration and potential for soil erosion, while active carbon serves as an indicator of a readily-available food source for microbial activity, and soil organic matter serves as a mediator for the soil physical, chemical, and biological processes. The sites include: three Purdue Agricultural Centers, two soil and water conservation district sites, 12 farmer sites with conservation cropping systems, and seven conventional comparison sites. The treatments consisted of cover crop versus no cover crop use, or cover crop use with different tillage systems or nitrogen rates. In 2016 and 2017, soil samples were collected at a depth of 0-5 cm, air-dried, and separated into two soil size fractions: 0-2 mm and 2-8 mm. The wet sieve method was used to measure the mean weight diameter of the water stable soil aggregates from the 2-8 mm size fraction in both years. The potassium permanganate method was used to measure the soil active carbon from both size fractions in both years. The dry combustion method was used to measure the soil organic matter from both soil size fractions in 2017 only. Results showed relatively small improvements in soil active carbon and aggregate stability with the addition of three to four years of cover crops to the long-term no-till systems. However, these improvements were greater when comparing the cover crops plus no-till treatments to the conventional-till without cover crops. More work is needed to understand the dynamics of soil aggregate stability, soil active carbon, and soil organic matter in relation to soil health and cover crop use. Cover crops will likely have more impact on soil aggregate stability, active carbon, and organic matter with a longer duration of use.</p><p></p>

Since agriculture began, field management has been at the forefront of expanding food production beyond previous limitations. Agricultural productivity is closely related to the physical, chemical, and biological properties of the soil. Landscape position and field management are among primary factors affecting these soil properties. Delineation of topographic positions of the field surface by shape (i.e., convex, concave, and linear) characterizes areas that may accumulate or lose soil and nutrients either during a discrete event or cumulatively over several growing seasons. Increased soil compaction, degradation of soil structure, and erosion have all been attributed to declining agricultural production. In addition to the physical disturbance from cultivation, erosion and deposition of soil components in different landscape positions explain a large part of the heterogeneity of soil properties across an agriculture field. In response to this, conservation tillage techniques, precision agriculture, and other novel management strategies have been developed to reduce negative impacts conventional row crop production such as nutrient pollution and compaction while optimizing farmer inputs. The objective of this project was to evaluate effects of topographic position and conservation tillage techniques on soil physical, chemical, and biological properties on the field scale as well as correlate certain soil attributes with suspended soil runoff collected during the sprinkle infiltration test. Soil fertility sampling was completed every fall from 2011 to 2014 and additional sampling of soil physical properties was taken in the spring between 2013 and 2014. Differences between fall conservation tillage treatments, no-till (NT), AerWay® aerator (AA), and Great Plains Turbo-Till® (GP), and topographic positons, concave, convex and linear were analyzed. Sediment runoff and earthworm biomass were also collected in the fall in 2014. Results indicated a significant increase of soil organic matter (12%-24%), water stable aggregates (78%-98%), phosphorus (43%-76%), and cation exchange capacity (28%-35%) within concave over the convex landscape positions. Soil strength was significantly lower in the field managed with the GP vertical tillage disk compared with the AA field to a depth of 27.5 cm and the NT field to depth of 17.5 cm. Crop residue coverage (percent covered) was more complete in the NT field (12%) and the GP field (3%) compared with the AA field. Suspended sediment runoff was negatively correlated with water-stable aggregates, Ca, and Mg, but positively correlated with earthworm biomass. Extractable nutrients and soil physical properties were also strongly affected by air temperature and precipitation throughout the study period. Characterizing soil properties within topographic positions has potential applications in precision agriculture management, such as reducing excessive fertilization, and identifying areas of increased pollution potential. Evaluation of the tandem effects of conservation tillage tools and topographic position within central Illinois is important in order for the optimization of production and conservation of resources. Physical disturbance from tillage and the transport of sediment from eroded areas to depositional topographic positions are key factors influencing the variability of soil properties, crop productivity, and potential sediment-borne nutrient pollution within individual agricultural fields.

Este trabalho apresenta a análise de agregados reciclados de telhas de cerâmica vermelha, visando seu emprego em camadas de pavimentos de baixo custo, baseado em estudos de laboratório. A indústria de cerâmica vermelha gera refugos da queima que são tratados como resíduos, mas se constituem em materiais de alto conteúdo energético e matéria prima de qualidade. O quadro da geração desses resíduos foi diagnosticado nas cidades de Monte Carmelo e Ituiutaba, em Minas Gerais. Os dados quantitativos obtidos indicam que é justificável a sua reciclagem. Somente na cidade de Monte Carmelo, as quantidades geradas permitiriam executar 10,8 km de camada de base de pavimento, ao se misturar 40% de solo poderia atingir 32 km por ano. Aproximadamente 10 t destes resíduos foram britadas obtendo-se o agregado reciclado de telha (ART). Estes agregados foram caracterizados mediante os ensaios físicos e mecânicos, e submetidos aos ensaios empregados na pavimentação, como a metodologia tradicional, metodologia MCT, método da pastilha, resistência ao cisalhamento, outros ensaios denominados índices de qualidade, ensaio de módulo resiliente e deformação permanente. Apesar deste material atender aos principais requisitos da metodologia tradicional, identificou-se que ele quebra com a aplicação de energia de compactação e de tensões nos ensaios, e apresenta alta resiliência - grandes deformações resilientes-, o que levaria à perda da capacidade de suporte da estrutura do pavimento, por fadiga. Desenvolveu-se uma metodologia para a determinação da absorção no estado saturado superfície seca, de agregados porosos, com fração fina inclusive, pois os métodos conhecidos não são aplicáveis; esta metodologia pode ser aprimorada para se constituir em norma de ensaio. Estudou-se um método inédito para a otimização do volume compactado da mistura de agregado com solo, baseado na porosidade do material granular, como uma alternativa ao método da estabilização granulométrica que se mostrou inadequado, no caso. As misturas produzidas com solos lateríticos foram avaliadas após a compactação não apresentando mais a quebra dos grãos do agregado, e mostraram ganhos expressivos no valor do módulo de resiliência, chegando em um caso a atingir 288% acima do módulo do agregado. Os resultados dos ensaios de laboratório indicaram ser possível a aplicação deste material em misturas com solos lateríticos, em camadas de pavimentos de baixo custo. / The purpose of this work is to use recycled aggregate of ceramics roofing tiles for low cost pavement layers, based on laboratory studies. The heavy-clay ceramic industry generates wastes, originated from the calcination stage, that are considered as residues which demand resources for its deposition. However they are high energy content materials which can be useful. The generation of these residues in the cities of Monte Carmelo and Ituiutaba, in the State of Minas Gerais indicated that its recycling is valid. For instance, in the city of Monte Carmelo, it is generated such a large amount of residues that it should be enough to execute about 10,8 km of base course of pavement; moreover if 40% of soil is mixed 32 km pavement per year can be produced. For this study, approximately 10 metric tones of these residues had been crushed to produce the recycled aggregate from roofing tile. The aggregates produced had been characterized by physical and mechanical tests. They were also submitted to the tests used for aggregates for pavement, such as the traditional methodology, methodology MCT (tropical compacted miniature), shear strength, resilient module, permanent deformation, and other tests called quality rates. These residues comply with the main requirements of the traditional methodology, however it is necessary to point out that the material breaks with the application of energy for compaction and under the tensions during the mechanical tests, it also presents high resilience, or great resilient deformations, which will lead to the loss of the supporting capacity of the pavement due to fatigue. An appropriate methodology was developed for the porous aggregate absorption measurement, including its fraction, in the saturated dry surface state. As the known methods for absorption are not applicable, this methodology with improvements can be proposed as standard test. A new method to optimize the compacted volume of the mixture was studied, based on the porosity of the granular material, as an alternative to the traditional method of the grain sized stabilization, which is not adequate for this purpose. The mixtures produced with lateritics soils were evaluated after the compacting, they have not presented the broken grains. These mixtures performed very well with significant increase in the value of the resilience module, up to 288% above of the module of the aggregate. The results of the laboratory indicate that it is possible to use these residues in mixtures with laterític soil, for layers of low cost pavements.

Agronomijos studijų programos magistro baigiamasis darbas 40 puslapių, 10 paveikslų, 2 lentelės, lietuvių kalba. Tyrimo objektas: paprastojo miežio (Hordeum vulgare L.) vasarinės veislės ,,Simba'' agrocenozė. Tyrimo tikslas: Įvertinti ilgalaikio skirtingo intensyvumo žemės dirbimo poveikį miežių agrocenozei, taikant intensyvias technologijas. Tyrimo uždaviniai: 1. Apžvelgti mokslinę literatūrą ir atlikti sisteminę analizę tiriamuoju klausimu. 2. Aprašyti atlikto eksperimento vykdymo sąlygas ir metodus. 3. Tyrimais nustatyti ir įvertinti ilgalaikio skirtingo intensyvumo žemės dirbimo poveikį struktūros patvarumui, miežių sudygimui, pasėlių piktžolėtumui ir miežių produktyvumui. Tyrimo metodai: mokslinės literatūros apžvalga, loginė analizė ir sintezė, statistinė analizė, palyginamoji analizė, grafinio modeliavimo technikos. Tyrimo rezultatai: • Pirmoji dalis pristato Lietuvos ir užsienio autorių mokslinės literatūros analizę. Mokslinė medžiaga atrinkta, susisteminta ir analizuota. • Antroje dalyje aprašyti koncentruojamasi ties bandymo schema ir parametrais, mokslinio eksperimento variantais ir duomenų analizės stebėjimais ir metodais. • Trečioji dalis identifikuoja dirvožemio struktūros patvarumą, miežių sudygimą ir stiebų produktyvumą, miežių derlių, pasėlių piktžolėtumą bei miežių produktyvumą. Nustatyta, kad ilgalaikis skirtingo intensyvumo žemės dirbimas neturėjo esminės įtakos dirvožemio struktūros patvarumui. Nenustatyta esminės įtakos ir miežių produktyvumui... [toliau žr. visą tekstą] / Final work of University Undergraduate/Master Studies 47 pages, 9 figures, 2 tables, the Lithuanian language. Object of the research: barley (Hordeum vulgare L.) spring variety Simba'' agrocenoses. Aim of the research: to evaluate the long-term effect of different soil tillage intensity on barley agrocenosis applying intensive technologies. Objectives of the research: 1. Review of the literature and perform a systematic analysis of the relevant issue. 2. Describe an experiment carried out with the conditions and methods. 3. Studies to identify and evaluate the long-term differences in the intensity of tillage effects on structural stability, barley germination, weed infestation and barley productivity. Research methods: review of scientific literature logical analysis and synthesis, statistical analysis, comparative analysis, graphical modelling techniques. Research results: • Part One presents Lithuanian and foreign scientific literature. Scientific material selected, structured and analysed. • Part Two describe the focus is on testing scheme and the parameters of the scientific variants of the experiment and data analysis methods and observations. • Part Three identifies the soil structure stability, barley germination and stem productivity of barley harvest, weed and barley crop productivity. It was established, that tillage intensity had no significant effect on soil aggregate stability and on barley productivity parameters except the number of germinating barley... [to full text]

Submitted by Viviane Lima da Cunha (viviane@biblioteca.ufpb.br) on 2017-07-18T14:24:48Z No. of bitstreams: 1 arquivototal.pdf: 2067734 bytes, checksum: 2652e3f89ed57e78708b4b935559e37a (MD5) / Made available in DSpace on 2017-07-18T14:24:48Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2067734 bytes, checksum: 2652e3f89ed57e78708b4b935559e37a (MD5) Previous issue date: 2015-09-22 / Paving works require a great demand for materials, mainly to be used in granular layers of pavements.In many cases, the available materials do not provide suitable characteristics for use, if necessary, therefore, the application of techniques to improve their characteristics, or even carry out the search for new materials in other regions.In this sense, this research objectives to study the particle size stabilization of a local soil from the addition of limestone aggregates for use in granular layers of pavements.The soil is classified as a sandy soil and has low plasticity.The limestone aggregate presents all the fractions in its composition, with the predominance of coarse fraction, and low resistance. Accord in to the results of particles size distribution of soil and limestone aggregate it was determined the proportion of each material in the soil-aggregate mixtures.For this, the C and D particle size ranges for well graded stabilized bases from DNIT were considered.The mixtures were determined in three scenarios with addition of soil 25%, 50% and 75% limestone aggregates in relation to their mass.The results carried out increasing coarse soil fractions and decreasing of plasticity, as the aggregate content in the mixture was increased. With respect to mechanical properties, California Bearing Ratio, resilience modulus and compressive strength carried out for the mixtures were bigger than the soil and the limestone aggregate.In all mechanical tests, the best results were carried out for mixtures consisting of 50% soil and 50% aggregates, provided by biggest stability in function of particles rearrangement.That way, it can be concluded that the sandy soil and limestone aggregates mixtures can be used in sub-base layers for paving. / As obras de pavimentação requerem uma grande demanda por materiais, principalmente para serem empregados em camadas granulares de pavimentos. Em muitos casos, os materiais disponíveis não apresentam características adequadas para uso, sendo necessário, dessa forma, a aplicação de técnicas que melhorem as suas características, ou ainda, realizar a busca por novos materiais em outras regiões. Nesse sentido, esta pesquisa tem por objetivo estudar a estabilização granulométrica de um solo local, a partir da adição de agregados calcários para uso em camadas granulares de pavimentos. O solo utilizado classifica-se como um solo arenoso e possui baixa plasticidade. O agregado calcário apresenta todas as frações em sua composição, com a predominância da fração graúda, e baixa resistência. Com os resultados da distribuição das partículas do solo e do agregado calcário foram determinadas a proporção de cada material nas misturas solo-agregado. Para isso, as faixas granulométricas C e D para bases estabilizadas granulometricamente do DNIT foram consideradas. As misturas foram determinadas em três cenários, sendo adicionados ao solo 25%, 50% e 75% de agregado calcário em relação a sua massa. Os resultados mostraram o aumento das frações grosseiras no solo e a redução da plasticidade, à medida que o teor do agregado na mistura aumentou. Com relação às características mecânicas, determinadas pelo Índice de Suporte Califórnia, módulo de resiliência e resistência à compressão simples, as misturas apresentaram resultados melhores que o solo e agregado calcário. Em todos os ensaios de caracterização mecânica, os melhores resultados foram observados para as misturas compostas por 50% de solo e 50% de agregado, pela maior estabilidade em função do rearranjo das partículas. Assim, conclui-se que o agregado calcário pode ser empregado em mistura com solo arenoso, com uso restrito para camadas de sub-base de pavimentos.

Este trabalho apresenta a análise de agregados reciclados de telhas de cerâmica vermelha, visando seu emprego em camadas de pavimentos de baixo custo, baseado em estudos de laboratório. A indústria de cerâmica vermelha gera refugos da queima que são tratados como resíduos, mas se constituem em materiais de alto conteúdo energético e matéria prima de qualidade. O quadro da geração desses resíduos foi diagnosticado nas cidades de Monte Carmelo e Ituiutaba, em Minas Gerais. Os dados quantitativos obtidos indicam que é justificável a sua reciclagem. Somente na cidade de Monte Carmelo, as quantidades geradas permitiriam executar 10,8 km de camada de base de pavimento, ao se misturar 40% de solo poderia atingir 32 km por ano. Aproximadamente 10 t destes resíduos foram britadas obtendo-se o agregado reciclado de telha (ART). Estes agregados foram caracterizados mediante os ensaios físicos e mecânicos, e submetidos aos ensaios empregados na pavimentação, como a metodologia tradicional, metodologia MCT, método da pastilha, resistência ao cisalhamento, outros ensaios denominados índices de qualidade, ensaio de módulo resiliente e deformação permanente. Apesar deste material atender aos principais requisitos da metodologia tradicional, identificou-se que ele quebra com a aplicação de energia de compactação e de tensões nos ensaios, e apresenta alta resiliência - grandes deformações resilientes-, o que levaria à perda da capacidade de suporte da estrutura do pavimento, por fadiga. Desenvolveu-se uma metodologia para a determinação da absorção no estado saturado superfície seca, de agregados porosos, com fração fina inclusive, pois os métodos conhecidos não são aplicáveis; esta metodologia pode ser aprimorada para se constituir em norma de ensaio. Estudou-se um método inédito para a otimização do volume compactado da mistura de agregado com solo, baseado na porosidade do material granular, como uma alternativa ao método da estabilização granulométrica que se mostrou inadequado, no caso. As misturas produzidas com solos lateríticos foram avaliadas após a compactação não apresentando mais a quebra dos grãos do agregado, e mostraram ganhos expressivos no valor do módulo de resiliência, chegando em um caso a atingir 288% acima do módulo do agregado. Os resultados dos ensaios de laboratório indicaram ser possível a aplicação deste material em misturas com solos lateríticos, em camadas de pavimentos de baixo custo. / The purpose of this work is to use recycled aggregate of ceramics roofing tiles for low cost pavement layers, based on laboratory studies. The heavy-clay ceramic industry generates wastes, originated from the calcination stage, that are considered as residues which demand resources for its deposition. However they are high energy content materials which can be useful. The generation of these residues in the cities of Monte Carmelo and Ituiutaba, in the State of Minas Gerais indicated that its recycling is valid. For instance, in the city of Monte Carmelo, it is generated such a large amount of residues that it should be enough to execute about 10,8 km of base course of pavement; moreover if 40% of soil is mixed 32 km pavement per year can be produced. For this study, approximately 10 metric tones of these residues had been crushed to produce the recycled aggregate from roofing tile. The aggregates produced had been characterized by physical and mechanical tests. They were also submitted to the tests used for aggregates for pavement, such as the traditional methodology, methodology MCT (tropical compacted miniature), shear strength, resilient module, permanent deformation, and other tests called quality rates. These residues comply with the main requirements of the traditional methodology, however it is necessary to point out that the material breaks with the application of energy for compaction and under the tensions during the mechanical tests, it also presents high resilience, or great resilient deformations, which will lead to the loss of the supporting capacity of the pavement due to fatigue. An appropriate methodology was developed for the porous aggregate absorption measurement, including its fraction, in the saturated dry surface state. As the known methods for absorption are not applicable, this methodology with improvements can be proposed as standard test. A new method to optimize the compacted volume of the mixture was studied, based on the porosity of the granular material, as an alternative to the traditional method of the grain sized stabilization, which is not adequate for this purpose. The mixtures produced with lateritics soils were evaluated after the compacting, they have not presented the broken grains. These mixtures performed very well with significant increase in the value of the resilience module, up to 288% above of the module of the aggregate. The results of the laboratory indicate that it is possible to use these residues in mixtures with laterític soil, for layers of low cost pavements.

Efficient road network and connectivity play vital role in the development of any country. Majority of the rural roads are unpaved and connectivity of rural roads is always a major challenge. Unpaved roads are also used for temporary transportation facilities like access roads, haul roads for mines, forest roads and parking lots. Since these roads do not have asphalt surfacing, they are subjected to early failures due to distresses like rutting, pot holes and depressions . Stabilization of unpaved roads using geosynthetics has been proved to be promising in increasing the lifespan of these roads because they facilitate economical, aesthetic and effective design of the roads. Inclusion of geosynthetic layers at the interface of subgrade soil and granular sub-base, reduces the surface heave, ensures a better stress distribution and reduces the stresses transferred to the subgrade soil, as demonstrated by earlier researchers. Wide variety of geosynthetics like woven and nonwoven geotextiles, uniaxial and biaxial geogrids and geocells are used as reinforcement in road sections. Geotextiles improve the strength by interfacial friction, lateral restraint and membrane effect. Geogrids provide additional benefit of interlocking. Geocells are honeycomb shaped geosynthetic cellular confining systems filled with aggregates in which the reinforcement action is derived not only by friction and interlocking, but also by confinement. Load-deformation characteristics of reinforced soil-aggregate systems under static, repeated and cyclic loads is a potential topic of interest considering the fact that the design of geosynthetic reinforced unpaved roads is still under development and experimentation. The objective of the present study is to understand the beneficial use of geosynthetics in unpaved roads and to provide clear insight into the influence of geosynthetics on the cyclic loading characteristics of unpaved roads through laboratory experiments. California Bearing Ratio (CBR) tests were carried out on unreinforced and reinforced soil-aggregate systems to study the effect of various parameters such as type of reinforcement, form of reinforcement, quantity of reinforcement, and water content of the subgrade soil on the load-penetration response of the various systems. Modified CBR tests were also carried out to understand the influence of boundary of the mould and anchorage of reinforcement on the behavior of reinforced soil-aggregate systems. Behavior of unreinforced and reinforced soil-aggregate systems under repeated and cyclic loading is also studied to understand the resilience of the composite systems. From the measured stress-strain response, the elastic and plastic strains developed in various systems are compared. Different moduli such as secant modulus, cyclic modulus and resilient modulus are computed for different systems and compared. To investigate the effectiveness of geosynthetics in improving the load - bearing capacity, repeated load tests were carried out on model sections of unpaved road constructed in a steel test tank of size 750 mm × 750 mm × 620 mm. The effect of various parameters like the form of reinforcement, quantity of reinforcement, height of geocell layer and the position of geocell layer on the load-deformation behaviour of the unpaved model road sections was studied. Static and cyclic triaxial tests were carried out on unreinforced and reinforced granular sub-base materials to understand their stress strain behavior under static and cyclic loading conditions. The influence of quantity and form of reinforcement on the stress-strain behaviour of these materials was studied. From the studies it is observed that the use of reinforcement increases the CBR value of the soil-aggregate systems. Studies with two different sizes of CBR moulds indicated that the boundary effect in the standard CBR mould leads to the overestimation of the CBR value, resulting in unconservative design of road sections. Providing anchorage to the reinforcement in CBR tests did not produce an appreciable change in the load-penetration behavior. From the repeated load tests it was observed that the reinforced systems did not show any improvement in the load-deformation behaviour at low levels of rut depth. At higher rut depths, the reinforced systems developed less plastic settlements and more elastic settlements and low resilient modulus compared to unreinforced systems. From the model tests on unpaved road sections, it was observed that the improvement in the cyclic load resistance of the road due to the inclusion of geocell layer depends on the height of the geocell layer and its position. Increasing the height of geocell layer resulted in improved performance up to certain height of the geocell layer, beyond which, further increase in the height reduced the load resistance because of the inadequate granular overlay thickness and inadequate compaction of aggregate within the geocell pockets. Static and cyclic triaxial tests showed that the geogrid and geocell reinforced granular sub-base material sustained higher peak stresses and exhibited increase in modulus compared to the unreinforced specimens. Results of element and model tests carried out in this study gave important insight into the load-deformation characteristics of reinforced soil-aggregate systems under static, repeated and dynamic loads. The results provide guidelines regarding the selection of type, quantity and configuration of geosynthetic reinforcement while designing unpaved roads and the expected performance of these reinforced unpaved roads.

A construção civil gera impactos ambientais que merecem atenção especial, uma vez que é uma das áreas que mais produz resíduos dentre as atividades econômicas. Os agregados reciclados de resíduos de construção e demolição podem ser utilizados em diversas áreas, apresentando desempenhos mecânico e hidráulico adequados quando comparados aos agregados naturais. Esta pesquisa consiste em estudar a viabilidade o uso de agregado reciclado misto (ARM) e misturas solo-ARM como materiais geotécnicos em camadas de bases e sub-bases de pavimentos. Para isso, foram realizados ensaios de caracterização física e comportamento mecânico. Para comparação, foram estudados também um agregado natural (AN) e uma mistura de solo-AN. Os resultados mostraram que a energia de compactação teve efeito positivo sobre o comportamento do ARM e misturas de solo-ARM. Observou-se ainda que o ARM apresentou ganho de resistência e rigidez devido ao efeito de auto-cimentação. No que se refere à adição de solo, as misturas de solo-ARM apresentaram uma diminuição no valor de CBR em relação a misturas compostas exclusivamente por ARM, contudo houve um aumento nas demais propriedades mecânicas. Com base nos resultados obtidos, pode-se concluir que o ARM e as misturas solo-ARM apresentam características físicas e comportamento mecânico adequados para uso em camadas de base e sub-base de pavimentos urbanos. / Civil construction generates environmental impacts that deserve special attention, since it is one of the areas that produces the most waste among economic activities. The recycled aggregates of construction and demolition waste can be used in several areas, presenting adequate mechanical and hydraulic performances when compared to natural aggregates. This research consists of studying the feasibility of using recycled mixed aggregate (RMA) and soil-RMA mixtures as geotechnical materials in base and sub-base layers of pavements. For that, tests of physical characterization and mechanical behavior were carried out. For comparison, a natural aggregate (NA) and a soil-NA mixture were also studied. The results showed that the compaction energy had a positive effect on the behavior of RMA and soil-RMA mixtures. It was also observed that the RMA showed strength gain and stiffness due to the self-cementing properties. Concerning soil addition, the soil-RMA mixtures presented a decrease in the CBR value in relation to mixtures exclusively composed by RMA, but there was an increase in the other mechanical properties. Based on the results obtained, it can be concluded that the RMA and the soil-RMA mixtures present physical characteristics and mechanical behavior suitable for the use in base and sub-base layers of urban pavements.

A construção civil gera impactos ambientais que merecem atenção especial, uma vez que é uma das áreas que mais produz resíduos dentre as atividades econômicas. Os agregados reciclados de resíduos de construção e demolição podem ser utilizados em diversas áreas, apresentando desempenhos mecânico e hidráulico adequados quando comparados aos agregados naturais. Esta pesquisa consiste em estudar a viabilidade o uso de agregado reciclado misto (ARM) e misturas solo-ARM como materiais geotécnicos em camadas de bases e sub-bases de pavimentos. Para isso, foram realizados ensaios de caracterização física e comportamento mecânico. Para comparação, foram estudados também um agregado natural (AN) e uma mistura de solo-AN. Os resultados mostraram que a energia de compactação teve efeito positivo sobre o comportamento do ARM e misturas de solo-ARM. Observou-se ainda que o ARM apresentou ganho de resistência e rigidez devido ao efeito de auto-cimentação. No que se refere à adição de solo, as misturas de solo-ARM apresentaram uma diminuição no valor de CBR em relação a misturas compostas exclusivamente por ARM, contudo houve um aumento nas demais propriedades mecânicas. Com base nos resultados obtidos, pode-se concluir que o ARM e as misturas solo-ARM apresentam características físicas e comportamento mecânico adequados para uso em camadas de base e sub-base de pavimentos urbanos. / Civil construction generates environmental impacts that deserve special attention, since it is one of the areas that produces the most waste among economic activities. The recycled aggregates of construction and demolition waste can be used in several areas, presenting adequate mechanical and hydraulic performances when compared to natural aggregates. This research consists of studying the feasibility of using recycled mixed aggregate (RMA) and soil-RMA mixtures as geotechnical materials in base and sub-base layers of pavements. For that, tests of physical characterization and mechanical behavior were carried out. For comparison, a natural aggregate (NA) and a soil-NA mixture were also studied. The results showed that the compaction energy had a positive effect on the behavior of RMA and soil-RMA mixtures. It was also observed that the RMA showed strength gain and stiffness due to the self-cementing properties. Concerning soil addition, the soil-RMA mixtures presented a decrease in the CBR value in relation to mixtures exclusively composed by RMA, but there was an increase in the other mechanical properties. Based on the results obtained, it can be concluded that the RMA and the soil-RMA mixtures present physical characteristics and mechanical behavior suitable for the use in base and sub-base layers of urban pavements.

Currently there is no suitable and commonly used device for volumetric quantification of snowmelt erosion in the Czech Republic (CR). The determination of erosion rate in the catchment is a essential prerequisite for the correct design of conservation measures. The thesis tries to offer the possible ways of monitoring the snowmelt erosion, compares individual methods and defines their optimal use. In the first year of the research, a runoff plot was developed to capture sheet erosion. The thesis compares also the methods using mobile devices - erosion bridge method and UAV photogrammetry - as effective instrument for snowmelt erosion monitoring. So far, no attention has been paid to snowmelt erosion in CR. Therefore, the thesis focuses mainly on the analysis of causal factors specific to this type of erosion - the erosion potential of snow cover and the possible soil erodibility changes due to freeze-thaw cycles. The thesis assesses the rate of snowmelt erosion risk in selected climatically different catchments and its changes in recent years. shows the timeliness of the problem. In the end, the thesis presents possibilities for solving the problem. The thesis claims the problem of snowmelt erosion actual and offers its possible solution.