[pt] Os pavimentos nada mais são que um sistema de múltiplas camadas, solicitados por um pneumático. Nas últimas três décadas inúmeras pesquisas tem sido direcionadas para o estudo de pavimentos. Porém, estas são complicadas, pois os pavimentos são estruturas físicas com interações de um grande número de fatores complexos e interdependentes. Dentre esses,podemos citar os parâmetros geotécnicos dos materiais, as características geométricas das camadas, a forma e intensidade do carregamento e fatores naturais. Este estudo consiste na análise paramétrica de um sistema de múltiplas camadas,representado por um pavimento constituído de base, sub-base e subleito. São apresentados gráficos normalizados de tensões e deslocamentos, resultados de uma análise por elementos finitos, utilizando, para isso, o programa LUSAS. Com base nos resultados, são analisados aspectos com relação ao desempenho do sistema, tais como: geração de poro-pressão, zona de tração, solicitações drenadas e não- drenadas,variação da geometria do conjunto e variação das propriedades geotécnicas dos materiais. Este estudo também compara os resultados encontrados com outras proposições. É verificada uma forte dependência do comportamento de pavimentos com relação às suas características geométricas e propriedades geotécnicas. / [en] This work presents an experimental study of the behavior of rockfills, focusing on the changes caused by rock alteration on the physical and mechanical characteristics, such as, lithology, gradation, deformability and strength. The basalt rockfill used in the construction of Marimbondo dam has been considered, with about 25 years of in situ alteration, together with intact basalts samples from Rio Grande quarry, which is located about 500m downstream from the dam site. The experimental results were also compared with data from tests on granite rockfill samples from Serra da Mesa dam. A methodology is proposed for evaluating the alterability of rockfills, based on laboratory tests on intact and alterated samples. Procedures for fast rock alteration in the laboratory were also developed, attempting to simulate the naturally slow alteration which occurs in the field. The laboratory alteration made use of both continuous leaching and wetting-drying cycles on intact basalt samples. The leaching was imposed in a large scale soxhlet equipment developed in the geotechnical laboratory at PUC-Rio. For the characterization of the geomechanical behavior of the rockfill masses, large scale equipments have been used, such as an confined compression chamber, triaxial compression machine and direct shear box. The results indicate that the intrinsic characteristics play an important role on the rockfill behavior. Furthermore, basalt alteration occurring in the field or in the laboratory may cause a significant decrease on the rockfills stiffness and strength parameters, as well as na increase on the abrasion characteristics of rockfills particles. This study also indicates that leaching in large scale equipment is a proper way to simulate the basalts natural alteration in accelerated laboratory conditions, making possible the long time prevision of the behavior of rockfills. Considering a time period of 75 years of natural alteration in the field, this work presents a quantitative prediction of Marimbondos rockfill behavior in terms of particle breakage, abrasion resistance, compressibility modulus M, deformability modulus E, unconfined strength qu and strength envelope parameters.

This study investigated the influence of material properties on fatigue life through laboratory fatigue testing of eleven Superpave hot mix asphalt (HMA) mixtures in use at the Virginia Smart Road. Mixtures were sampled from the plant and produced in the laboratory to investigate the influence of production method. Specimens were cut from the in-situ pavement and compacted in the laboratory to evaluate the influence of compaction method. Third point beam fatigue testing was performed at 25ºC and 10Hz. Additional testing at frequencies of 1 Hz and 5Hz, and at 10 Hz including rest periods of 0.4sec and 0.9sec were performed for one mixture to explore the impact of frequency and rest periods. Analyses were performed on the strain-life relationships and predicted endurance strain limits for the mixtures. Investigation of strain-life relationships for several mixtures indicated that small differences in mixture volumetrics due to the production method have minimal impact on the laboratory fatigue performance of HMA. Comparisons of expected fatigue performance for one mixture indicated that shorter fatigue lives (under the same strain conditions) may be expected for laboratory-compacted specimens when compared to field-compacted specimens, despite visual observation of damage (surface cracking) in the field-compacted specimens. Testing performed on one mixture to determine the influence of different loading frequencies showed that fatigue life was independent of the requencies tested. Investigation of rest period inclusion indicated no differences in fatigue life for loading conducted at 10 Hz frequency and no rest period, 0.4sec rest period, or 0.9sec rest period. The evaluation of specimens cut from the in-situ pavement indicated that location within the lane and orientation did not significantly affect laboratory fatigue performance. The effect of aggregate size was considered; however, results were inconclusive. Using predictive strain-life fatigue equations, the benefits of polymer-modification of binders and use of SMA were shown for mixtures produced in the laboratory according to the job mix formula and to match the plant-produced volumetrics. Evaluation of the predicted fatigue strain endurance limit was performed using an energy-based and an empirical method. The energy method was shown to estimate significantly higher endurance limit strains for mixtures. / Ph. D.

Permeability of hot mix asphalt (HMA) is a property that is important to the pavement's durability. Measuring permeability along with density will give a better indication of a pavement's durability than density alone. The presence of water for extended periods of time in the pavement is directly linked to early deterioration. The first goal of this research is to study the anisotropic nature of hot mix asphalt permeability within the lab, which required the development of a horizontal permeameter. This method is inexpensive and suitable for a lab technician to use and analyze. A series of samples with different air void contents were used to observe how the ratio of vertical to horizontal permeability changes with air void content. The second goal was to develop a modified field permeameter to study the water-pavement contact area effect on field permeability. A reliable sealing system was created that is consistent and is not detrimental to the pavement surface. The results of the study show that larger contact areas yield increasing influence of vertical flow, which represents the one dimensional assumption of Darcy's Law falling head method. The third goal was to validate the results by simulating the field permeability test with a finite element model. A number of simulations with different permeability values and anisotropic permeability ratios were conducted. The horizontal and vertical flows were observed within the test area to analyze the flow pattern and influence of the directional permeability. The results matched the trends found in the field permeability study. / Master of Science

Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Hot Mix Asphalt (HMA) plays a large role in the transportation infrastructure and is used to construct highways, runways, parking areas, foot paths and cycle paths. Asphalt is thus being produced in massive amounts around the world. The latest figures on asphalt production indicate that 1.6 trillion metric tonnes of asphalt are produced annually worldwide. This vast quantity of asphalt produced annually has a significant effect on the environment, economy and the surrounding society. According to Mike Acott from the National Asphalt Pavement Association (NAPA) the key strategy to improve HMA is to continuously strive to improve the health safety and environmental practices of HMA. He also emphasises the importance of engaging improvements and innovation in the design and operation phases of HMA as it will result into more health, safety and environmental benefits. (Acott, 2007) It is thus important to improve the sustainability of HMA as it will be used for generations to come. The purpose of this study is to investigate the potential benefits and risks of applying new technology to the current methods of design and construction of asphalt by the South African asphalt industry. The technologies that are investigated in this study are Warm Mix Asphalt (WMA) technology and the use of Reclaimed Asphalt (RA). WMA is asphalt that is designed to be manufactured at a lower temperature than HMA. RA is the use of recycled asphalt material in Hot Mix Asphalt (HMA) thus replacing virgin aggregate and virgin bitumen with recycled components. Both these technologies can have an effect on the sustainability of HMA. This study investigates the benefits and risks of the integration and application of WMA technology and RA into HMA industry in South Africa. The study uses interviews along with environmental and cost analyses to investigate this integration. The findings show that these technologies have definite environmental and cost benefits and that the magnitude of these benefits cannot be ignored. The current use of these technologies is a cause for concern as they are used in limited projects and limited authorities have warmed up to the use of these technologies. The risks involved in using these technologies are caused by a lack of experience and knowledge of these technologies which is aggravated as there are no standard specifications for their use. It is important that the right strategy is put into place to integrate these technologies into the South African asphalt industry in such a way that minimal risk and monetary losses are achieved. / AFRIKAANSE OPSOMMING: HMA speel 'n groot rol in vervoer-infrastruktuur en word gebruik om paaie, aanloopbane, parkeerareas, voet en fiets paaie te bou. Asfalt word dus wêreldwyd in groot hoeveelhede geproduseer. Die nuutste syfers toon dat 1.6 triljoen kubieke meter asfalt jaarliks wêreldwyd geproduseer word. Hierdie groot hoeveelheid asfalt wat geproduseer word het ‘n beduidende effek op die omgewing, ekonomie en die omliggende gemeenskap. Volgens Mike Acott van die Nasionale Asfalt Plaveisel Assosiasie (NAPA) is die voortdurende strewe om die gesondheids, veiligheids en omgewings impakte van HMA te verminder die sleutel-strategie om HMA te verbeter. Hy beklemtoon ook die belangrikheid om verbeterings en innovering in die ontwerp en bedryf fases van HMA aan te bring wat kan lei tot meer veiligheids, gesondheids en omgewings voordele. (Acott, 2007) Dit is dus belangrik om die volhoubaarheid van HMA te verbeter as dit bewaar wil word vir toekomstige geslagte te kom. Die doel van hierdie studie is om die potensiële voordele en risiko's van die gebruik van nuwe tegnologieë op die huidige ontwerp en konstruksie metodes in Suid-Afrika se asfalt bedryf te ondersoek. Die tegnologieë wat in hierdie studie ondersoek word is Warm Mengsel Asfalt (WMA) en die gebruik van Herwonne Asfalt (RA). WMA is asfalt wat ontwerp is om teen ‘n laer temperatuur as konvensionele HMA vervaardig te word. RA is die gebruik van herwinde asfalt in HMA wat lei tot die besparing van nuwe aggregaat en bitumen. Beide hierdie tegnologieë kan 'n invloed op die volhoubaarheid van HMA hê. Hierdie studie ondersoek dus die voordele en risiko's van die integrasie en gebruik van WMA en RA tegnologie in die HMA-industrie in Suid-Afrika. Die studie maak gebruik van onderhoude asook omgewings en koste impak analises om hierdie integrasie te ondersoek. Die bevindinge in die studie toon aan dat hierdie tegnologie definitief voordelig is vir die omgewing en die ekonomie en dat hierdie voordele groot genoeg is om nie geïgnoreer te word nie. Die huidige gebruik van hierdie tegnologieë is 'n rede vir bekommernis, want dit word slegs in ‘n paar projekte aangewend en daar is slegs ‘n paar owerhede wat die tegnologieë ondersteun. Die risiko's wat betrokke is in die gebruik van hierdie tegnologieë word veroorsaak deur 'n gebrek aan ondervinding en kennis van die tegnologieë wat verder vererger word deur die gebrek aan standaard spesifikasies vir die gebruik daarvan.

Este trabalho tem por objetivo avaliar o desempenho mecânico de misturas asfálticas densas quando submetidas ao processo de envelhecimento a curto prazo, em laboratório. Foram usados três tipos de cimento asfáltico : cimento asfáltico de petróleo (CAP 20 puro), cimento asfáltico modificado com 4,5% de polímero SBS (Styrene Butadiene Styrene) e cimento asfáltico modificado com 20,0% borracha reciclada de pneu (BRP). A curva granulométrica adotada é o centro da faixa \"C\" da especificação federal (DNER, 1997). Para simular o processo de envelhecimento a curto prazo durante as fases de estocagem, mistura, aplicação e construção, as misturas asfálticas foram acondicionadas de maneira solta em estufa de verificação por um período de 4 e 8 horas, a uma temperatura de 135ºC. Após o envelhecimento as misturas foram compactadas de acordo com o método de ensaio Marshall e submetidas aos ensaios mecânicos. Os resultados de ensaio de fluência por compressão uniaxial dinâmica mostraram que, em relação aos asfaltos puros, as misturas modificadas apresentam deformação total menor, quando submetidas ao processo de envelhecimento a curto prazo. Os resultados de ensaio de módulo de resiliência não permitiram distinguir claramente a influência do processo de envelhecimento a curto prazo nas misturas asfálticas modificadas com borracha. Já para as misturas modificadas com polímero, o módulo de resiliência aumentou quando estas misturas foram submetidas ao processo de envelhecimento a curto prazo. / The purpose of this research is to evaluate the modification of some mechanical properties of dense asphalt mixes due to short-term asphalt aging. Three type of binder were tested : CAP 20 asphalt cement (Petrol Asphalt Cement - 20, brazilian specification), SBS polymer-modified asphalt (Styrene Butadiene Styrene 4.5% + CAP 20) and recycled tire rubber-modified asphalt (rubber 20% + CAP 20). The grain size distribution of the aggregate conforms to grade \"C\" of the brazilian standard for bituminous concrete (DNER - Departamento Nacional de Estradas de Rodagem, 1997). In order to simulate the aging phenomenon that occurs during asphalt storage, mixture production, placement and compaction, the specimens of loose mixture were placed over a tray in a ventilated oven at 135ºC for 4 or 8 hours. After the aging period, if applicable, the mixture was compacted according to the Marshal method. Immediately after the compaction process the specimens were tested for uniaxial dynamic creep, tension by diametral compression, and resilience by dynamic diametral compression. Results of uniaxial dynamic creep test had shown that, after laboratory short-term aging, the total deformation accumulated by polymer or rubber modified mixtures are smaller than total deformation for plain asphalt. Resilient modulus tests, for rubber modified asphalts, were not conclusive about differences between mixtures before and after aging. However, for polymer modifiedasphalts, the resilient modulus increased as effect of short-term aging.

This study was carried out to evaluate the use of heated reclaimed asphalt pavement materials with emulsion and the use of hot mix asphalt with wax (Sasobit) as base course materials. Mixes with lower than optimum and optimum emulsion, as well as with heated reclaimed asphalt pavement material and optimum emulsion were made; also, mixes with conventional asphalt binder and those with asphalt binder and Sasobit were produced at relatively lower temperatures. These mixes were tested for workability, and all but one of the mixes were used for preparation of approximately 0.9 m (35 inches) by 0.9 m (35 inches) 0.125 m (5 inches) slabs. The rates of densification during the compaction of these slabs were compared. Samples cored from the slabs were tested for stiffness, and dry retained tensile strengths. The results showed that heating of reclaimed asphalt pavement material can improve the dispersion as well as densification significantly. The use of asphalt binder was found to be beneficial in improving strength and stiffness, and the use of Sasobit helped to achieve almost similar workabilities and compactabilities at lower temperatures, as compared to those of hot mix asphalt with neat asphalt binder. No significant difference was found between the modulus of the Sasobit and hot mix asphalt samples. The dispersion of asphalt binder seemed to improve with the use of Sasobit at lower mixing temperature. A field project is recommended for evaluating performance of emulsion mixes with heated reclaimed asphalt pavements and asphalt binder mixes with Sasobit.

Este trabalho tem por objetivo avaliar o desempenho mecânico de misturas asfálticas densas quando submetidas ao processo de envelhecimento a curto prazo, em laboratório. Foram usados três tipos de cimento asfáltico : cimento asfáltico de petróleo (CAP 20 puro), cimento asfáltico modificado com 4,5% de polímero SBS (Styrene Butadiene Styrene) e cimento asfáltico modificado com 20,0% borracha reciclada de pneu (BRP). A curva granulométrica adotada é o centro da faixa \"C\" da especificação federal (DNER, 1997). Para simular o processo de envelhecimento a curto prazo durante as fases de estocagem, mistura, aplicação e construção, as misturas asfálticas foram acondicionadas de maneira solta em estufa de verificação por um período de 4 e 8 horas, a uma temperatura de 135ºC. Após o envelhecimento as misturas foram compactadas de acordo com o método de ensaio Marshall e submetidas aos ensaios mecânicos. Os resultados de ensaio de fluência por compressão uniaxial dinâmica mostraram que, em relação aos asfaltos puros, as misturas modificadas apresentam deformação total menor, quando submetidas ao processo de envelhecimento a curto prazo. Os resultados de ensaio de módulo de resiliência não permitiram distinguir claramente a influência do processo de envelhecimento a curto prazo nas misturas asfálticas modificadas com borracha. Já para as misturas modificadas com polímero, o módulo de resiliência aumentou quando estas misturas foram submetidas ao processo de envelhecimento a curto prazo. / The purpose of this research is to evaluate the modification of some mechanical properties of dense asphalt mixes due to short-term asphalt aging. Three type of binder were tested : CAP 20 asphalt cement (Petrol Asphalt Cement - 20, brazilian specification), SBS polymer-modified asphalt (Styrene Butadiene Styrene 4.5% + CAP 20) and recycled tire rubber-modified asphalt (rubber 20% + CAP 20). The grain size distribution of the aggregate conforms to grade \"C\" of the brazilian standard for bituminous concrete (DNER - Departamento Nacional de Estradas de Rodagem, 1997). In order to simulate the aging phenomenon that occurs during asphalt storage, mixture production, placement and compaction, the specimens of loose mixture were placed over a tray in a ventilated oven at 135ºC for 4 or 8 hours. After the aging period, if applicable, the mixture was compacted according to the Marshal method. Immediately after the compaction process the specimens were tested for uniaxial dynamic creep, tension by diametral compression, and resilience by dynamic diametral compression. Results of uniaxial dynamic creep test had shown that, after laboratory short-term aging, the total deformation accumulated by polymer or rubber modified mixtures are smaller than total deformation for plain asphalt. Resilient modulus tests, for rubber modified asphalts, were not conclusive about differences between mixtures before and after aging. However, for polymer modifiedasphalts, the resilient modulus increased as effect of short-term aging.

Os objetivos deste trabalho são avaliar o comportamento de asfaltos peruanos convencional CAP PEN 60/70 e modificados por polímero SBS tipo I 60/60 e PG 76-22, em misturas asfálticas densas, sem e com envelhecimento em curto prazo, e estabelecer a distribuição do grau de desempenho (PG) de ligantes asfálticos com base nas condições climáticas de cada região do Peru. Para a classificação por desempenho os ligantes asfálticos procedentes de Peru foram submetidos aos ensaios convencionais e da especificação Superpave: penetração, ponto de amolecimento, viscosidade Brookfield, ponto de fulgor, retorno elástico, estabilidade a estocagem, envelhecimento em curto prazo (RTFOT), envelhecimento em longo prazo (PAV), cisalhamento dinâmico (DSR) e rigidez à fluência na flexão (BBR). Para a avaliação das propriedades mecânicas, sem envelhecimento e com envelhecimento em curto prazo, foram moldados um total de 196 corpos de prova, submetidos aos ensaios Marshall, resistência à tração, resistência à tração após umidade induzida, módulo de resiliência, fluência por compressão uniaxial estática, fluência por compressão uniaxial dinâmica e vida de fadiga. Os resultados dos ensaios mostram que o proceso de modificação dos asfaltos por polímero melhora as caracteristicas reológicas do ligante, apresentando menor índice de susceptibilidade térmica e maior resistência ao envelhecimento e melhorando o comportamento das misturas asfálticas em todos os ensaios mecânicos. Esses resultados foram confirmados pela análise estrutural com o programa computacional Elsym5, nas duas condições de envelhecimento estudadas. / The main goal of this work is the evaluation of the behavior of conventional peruvian asphalt binder AC PEN 60/70 and SBS polymer-modified asphalts I 60/60 and PG 76-22, when used in hot-mix asphalt (HMA), under both conditions with and without short-term aging. It aims also to establish the asphalt binder performance grade (PG), which is based on the weather conditions, for different peruvian regions. The peruvian asphalt binders were submitted to conventional and Superpave laboratory tests: penetration, softening point, Brookfield viscosity, flash point, elastic recovery, storage stability, rolling thin film oven test (RTFOT), pressure aging vessel (PAV), dynamic shear rheometer (DSR) and bending beam rheometer (BBR). For the evaluation of mechanical properties 196 specimen were sumitted to Marshall, indirect tensile strength under static loading, indirect tensile strength under static loading after induced moisture, resilient modulus under dynamic diametric compression, static and dynamic creep and fatigue tests. The result show that polymer-modified asphalt binder improve rheological characteristic, in terms of thermal susceptibility and resistance to aging, and also improve the asphalt mixtures behavior, which was verified in all of the mechanical tests and after the structural analysis performed with the Elsym5 program, for all of the short-term aging conditions studied in this work.

Low temperature cracking is attributed to tensile stresses induced in an asphalt concrete pavement that develop when the pavement is subjected to a cold temperature. Cracking results in poor ride quality and a reduction in service life of the pavement. Low temperature cracking has been predicted by regression equations, mechanistic approaches and by simulation measurements. The purpose of the study reported herein is to (1) evaluate the Thermal Stress Restrained Specimen Test (TSRST) as an accelerated performance test to simulate low temperature cracking of asphalt concrete mixtures and (2) develop a deterministic and probabilistic model to predict low temperature cracking with TSRST results. Construction histories, cracking observations and temperature data were collected for five test roads in Alaska, Pennsylvania and Finland. A full scale and fully controlled low temperature cracking test program was conducted at the U.S. Army Cold Regions Research and Engineering Laboratory (USACRREL). Specimens were fabricated in the laboratory with original asphalt cements and aggregates from the test roads. In addition, asphalt concrete pavement specimens were cut from the test sections. The TSRST results obtained for these samples were correlated with the field observations. Based on a statistical analysis of the data, the TSRST fracture temperature is associated with the field cracking temperature and crack frequency for the test roads where mixture properties dominated low temperature cracking. It was concluded that the TSRST can be used to simulate low temperature cracking of asphalt concrete mixtures. A deterministic and a probabilistic model were developed to predict crack spacing as a function of time using the TSRST results, pavement thickness and bulk density, pavement restraint conditions and air temperature. The affect of aging on pavement properties was incorporated in the models by predicting the field aging with Long Term Oven Aging (LTOA) treatment in the laboratory. The calculation of the crack spacing is based on the theory that the pavement slab cracks when the pavement temperature reaches the cracking temperature of the mixture and the slab is fully restrained. The deterministic model predicts crack spacing with time whereas the probabilistic model predicts crack spacing and its variation with time and yields the reliability of the design with regard to a minimum acceptable crack spacing criterion defined by road authorities. The models were verified by comparing the predicted crack spacings for the five test roads to the observed crack spacings. The probabilistic model is recommended for use in predicting the low temperature cracking of asphalt concrete mixtures. / Graduation date: 1994

Abstract Given that most utilities are located beneath public right of ways, it is difficult to perform repairs to the utility without significantly disturbing the existing roadway. Currently there are several standard orders of procedure that deal with small-scale repairs on asphaltic surfaces. This study investigates the use of Grade D Aggregate as a backfill during a utility repair versus the condition of the repair. Five East Tennessee utilities provided a total of 60 utility repair locations over three years of age; 30 of which incorporated Grade D Aggregate and 30 incorporated #57 Stone. The Tennessee Department of Transportation specifies a smoothness criterion of the roadway to regulate any deviation of the surface of the roadway greater than ¼ inch over a 12-foot span. The parameters measured during this study include smoothness, condition of the asphalt topcoat, adjacent stress cracking, depth of repair and disturbed surface area. Multiple linear regression and analysis of variance tests were used to analyze the results. Results suggest that there is no difference between using and not using Grade D Aggregate except with failures of one inch or greater. The results also suggest that there is little to no relationship between roadway characteristics and the performance of the repair except with failures one inch or greater. There is a correlation between slope and failures that had a deviation of one inch or greater. The results suggest that Grade D Aggregate performs better when significant failures occur. Recommendations include implementation of a cutback area, development and implementation of installation guidelines within the municipality, and implementation of a maintenance program that will address the repair cut failures in a timely manner.