998 resultados para FINAL DISPOSAL
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An ACC overlay is most often the rehabilitative effort used to maintain the serviceability of either an ACC or PCC pavement. The major problem in durability of this ACC overlay comes from reflective cracking. These cracks usually open, allowing water to enter the unsealed crack and strip the ACC in the overlay. The stripping of the ACC allows accelerated deterioration at the crack. Two engineering fabrics were evaluated in this project in order to determine their effectiveness in reducing reflective cracking. These two materials are: • PavePrep, Contech Construction Products Inc. • ProGuard, Phillips Fiber Corporation The data indicated a statistically significant decrease in reflective crack formation in the ProGuard fabric sections compared to control. There was little evidence of a similar effect from the PavePrep fabric sections compared to control. However, the rate of cracking (the rate of formation of new cracks) for both fabrics and control tended to be similar after three years. The benefits of using these fabrics (possible delay of some crack formation by two years) on this project did not outweigh the costs of up to $4200.00 per mile.
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Stopping and turning maneuvers on high traffic volume asphalt cement concrete surfaced roads and streets often cause distortion of the pavement. Distortion may show up as excessive rutting in the wheel path, shoving of the pavement and/or rippling of the surface. Often times repeated corrective work such as cold milling or heater planing is required in these areas to maintain the pavement surface in a reasonable condition. In recent years polymer additives have been developed for asphalt cement concrete paving mixes that show promise in improving the inplace stability of the pavements. AC-13 (Styrelf 13) available from Bitucote Products Company, St. Louis, Missouri is an asphalt cement that has been modified by an additive to exhibit characteristics of very high stability in asphalt mixes.
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In 1994 the Iowa Department of Transportation constructed a 7.2-mile Portland Cement Concrete overlay project in Iowa County on Iowa Highway 21. The research work was conducted in cooperation with the Department of Civil Engineering and the Federal Highway Administration under the Iowa Highway Research Board project HR-559. The project was constructed to evaluate the performance of an ultrathin concrete overlay during a 5-year period. The experiment included variables of base surface preparation, overlay depth, joint spacing, fiber reinforcement, and the sealed or non-sealed joints. The project was instrumented to measure overlay/base interface temperatures and strains. Visual distress surveys and deflection testing were also used to monitor performance. Coring and direct shear testing was accomplished 3 times during the research period. Results of the testing and monitoring are identified in the report. The experiment was very successful and the results provide an insight into construction and design needs to be considered in tailoring a portland cement concrete overlay to a performance need. The results also indicate a method to monitor bond with nondestructive methods.
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Recently, a number of roads have begun to exhibit the onset of deterioration at relatively early ages. Since this deterioration appears to be the result of materials issues, data concerning raw materials, design, and paving conditions have been collected and analyzed for correlation between independent variables and deterioration. This analysis shows that there is a positive and statistically significant correlation between deterioration and the following variables: alkali and sulfate content of the cementitious materials, impermeable base course, paving temperature, and the presence of fly ash. This study also concludes that there is a significant need for improvement in data collection and maintenance by many organizations responsible for the production of concrete
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O objetivo deste trabalho foi avaliar a massa de forragem, os componentes morfológicos e o valor nutritivo de Panicum maximum cultivar Tanzânia, com aplicação de uma segunda dose de adubação nitrogenada em março, no final do verão. Anualmente, foram aplicados em cobertura 50, 17,5 e 33,2 kg ha-1 de N, P e K, respectivamente, em novembro. Além disso, a metade da área recebeu 50 kg ha-1 de N adicional, em março. Os tratamentos foram doses de 50 e 100 kg ha-1 de N em pastos de capim-tanzânia. Os piquetes foram subdivididos em seis e submetidos ao pastejo rotacionado. Foram avaliados a massa de forragem, os componentes morfológicos e o valor nutritivo. A aplicação adicional de N, em março, promoveu aumento nas taxas de acúmulo de matéria seca verde e de lâmina foliares, com maiores efeitos no outono. Houve acréscimos nos teores de proteína bruta e de digestibilidade in vitro da matéria orgânica da forrageira logo após a aplicação do N. A adubação com 50 kg ha-1 por ano de N foi suficiente para manter a produção de forragem estável durante três anos, sob pastejo. A aplicação de 50 kg ha-1 por ano de N adicional, em março, diminuiu a estacionalidade da produção forrageira, além de produzir forragem de maior valor nutritivo durante o outono.
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The early-age thermal development of structural mass concrete elements has a significant impact on the future durability and longevity of the elements. If the heat of hydration is not controlled, the elements may be susceptible to thermal cracking and damage from delayed ettringite formation. In the Phase I study, the research team reviewed published literature and current specifications on mass concrete. In addition, the team observed construction and reviewed thermal data from the westbound (WB) I-80 Missouri River Bridge. Finally, the researchers conducted an initial investigation of the thermal analysis software programs ConcreteWorks and 4C-Temp&Stress. The Phase II study is aimed at developing guidelines for the design and construction of mass concrete placements associated with large bridge foundations. This phase included an additional review of published literature and a more in-depth investigation of current mass concrete specifications. In addition, the mass concrete construction of two bridges, the WB I-80 Missouri River Bridge and the US 34 Missouri River Bridge, was documented. An investigation was conducted of the theory and application of 4C-Temp&Stress. ConcreteWorks and 4C-Temp&Stress were calibrated with thermal data recorded for the WB I-80 Missouri River Bridge and the US 34 Missouri River Bridge. ConcreteWorks and 4C-Temp&Stress were further verified by means of a sensitivity study. Finally, conclusions and recommendations were developed, as included in this report.
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The overall aim of the project has been to assess the extent to which data on the frequency of occurence of STDs [Sexually transmitted diseases] might be useful in the monitoring and evaluation of AIDS prevention programmes. The objectives have been to answer the following questions: (a) Can measures of STD occurence be used as an outcome measure of AIDS/HIV preventive efforts ? In particular: -> which diseases might be useful ? -> in what ways could they be used ? (b) If measures of STD occurence can be used in this way, is existing surveillance data in Western Europe adequate for the purpose ? If not why not ? (c) What do data from existing STD surveillance systems tell us about the success or failure of AIDS prevention to date ? (d) What needs to be done in order taht STD surveillance data in the countries of Western Europe could be used for this purpose ? [Authors, p. 4]
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Most research current to the time of these projects was focused on use of Superpave mix designs on higher volume roads. Low volume roads have different requirements in terms of mix design, aggregate types, aggregate sources and project budgets. The purpose of this research was to determine if the Superpave mix design strategy for low volume roads was practical and economical. Eight projects were selected in five counties. The projects were completed in the summer of 1998. Performance evaluation of the resulting pavements was carried out annually. There was no significant increase in costs related to the use of Superpave. Nor were there any significant construction issues. There were some differences noted in placement and compaction in the field, but these were not serious.
Eficiência biológica e econômica de pasto de capim-tanzânia adubado com nitrogênio no final do verão
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O objetivo deste trabalho foi avaliar o ganho de peso vivo, a capacidade de suporte e a eficiência bioeconômica em pastos de Panicum maximum, cultivar Tanzânia, com aplicação de uma segunda dose de adubação nitrogenada no final do verão. Anualmente foram aplicados em cobertura: 50, 17,48, e 33,2 kg ha-1 de N, P e K, respectivamente, em novembro. A metade da área recebeu 50 kg ha-1 de N adicional em março. Os tratamentos foram pastos de capim-tanzânia com 50 e 100 kg ha-1 de N. Os piquetes foram submetidos ao pastejo rotacionado. Foram utilizados quatro animais por piquete, e animais adicionais foram colocados e removidos para manter resíduos semelhantes pós-pastejo. Não houve efeito da adubação nitrogenada sobre o ganho médio diário. No entanto, o pasto adubado com 100 kg ha-1 de N (1,8 UA ha-1) resultou em maior capacidade de suporte e maior produtividade (780 kg ha-1 por ano de PV) do que o adubado com 50 kg ha-1 de N (1,5 UA ha-1) e com 690 kg ha-1 por ano de PV, em média. A eficiência da conversão do N em produto animal foi de 1,8 kg de PV por hectare para cada quilograma adicional de N aplicado. O uso da adubação nitrogenada no final do verão é uma alternativa bioeconomicamente viável para a produção sustentável de carne.
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Cette étude est destinée à évaluer les effets des campagnes de Sida en Suisse auprès de jeunes en marge de la société que l'on qualifie de "zonards", en termes de modifications des représentations, attitudes et comportements face à cette maladie et aux manières de s'en protéger. Elle s'intéresse aussi aux modalités d'acquisition d'attitudes et comportements nouveaux, ainsi qu'à la manière dont les campagnes ont été accueillies et répercutées. [Auteurs, p. 5]
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Individuals with disabilities have civil rights protection similar to that provided to individuals on the basis of race, sex, national origin, and religion. The advent of the Americans with Disabilities Act has improved these protections and brought this issue into the forefront. This book is not intended to be a legal translation of state or federal laws. Its purpose is to assist people with disabilities in understanding their rights. Please consult the Code of Iowa, the appropriate federal laws or an attorney if you need a legal interpretation.
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Other Audit Reports - 28E Organizations
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Other Audit Reports - 28E Organizations
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