The study focuses on the issue of hot mix asphalt pothole repairs, the performance of which is greatly reduced by repair edge disintegration. This is caused by low interface temperatures which result in low density interfaces and poor repair bonding. The study examined heat flow in shallow and deep pothole excavations under controlled pre-heating done in heating-cooling cycles, referred as "dynamic heating", and the effect of asphalt thermal properties on this. Dynamic heating was applied with an experimental infrared heater operating between 6.6 kW and 7.7 kW heat power and with the heater being stationary or moving above simulated potholes at offsets of 130 mm and 230 mm. The study also examined heat flow in traditional non-heated shallow repairs, referred as "static repairs", and dynamic shallow repairs and the effect of pothole pre-heating in repair adhesion. Finite Element modelling was also used to enhance understanding of heat flow in the executed repairs. Then, the bonding properties and rutting resistance of the repairs were assessed using shear bond tests (SBT's) and wheel track tests (WTT's) respectively. The results showed that irrespective of excavation depth, heating power and heater offset, temperature distribution in the pothole excavation and inside the slabs under dynamic heat was non-uniform. Dynamically heating pothole excavations for approximately 10 minutes yields better heat distribution than 20 minutes heating time while minimising the possibility of asphalt overheating. The temperature profile at the interface of the dynamically heated repair is improved when compared to static repair suggesting better interface adhesion. A significant role in this profile is played by thermal contact conductance which determines the resistance to pavement-repair thermal conduction per unit area at the repair interface. This was reflected in the assessment and simulation of the repairs with the latter generating reasonable transient temperature profiles within the dynamically heated pothole excavation, at the interface of the repairs, and inside the host pavement. Further, the shear strength at the bottom and side interfaces of dynamically heated repairs was 78.2% and 68.4% higher respectively than that of static repairs. On average, static and dynamic repairs showed repair interface rutting depths of 14.82 mm and 10.36 mm respectively. It was concluded that dynamically heating a pothole excavation increases repair interface adhesion and repair durability.

Currently in Iowa, the amount of RAP materials allowed for the surface layer is limited to 15% by weight. The objective of this project was to develop quality standards for inclusion of RAP content higher than 15% in asphalt mixtures. To meet Superpave mix design requirements, it was necessary to fractionate the RAP materials. Based on the extensive sieve-by-sieve analysis of RAP materials, the optimum sieve size to fractionate RAP materials was identified. To determine if the higher percentage of RAP materials than 15% can be used in Iowa's state highway, three test sections with 30.0%, 35.5% and 39.2% of RAP materials were constructed on Highway 6 in Iowa City. The construction of the field test sections was monitored and the cores were obtained to measure field densities of test sections. Field mixtures collected from test sections were compacted in the laboratory in order to test the moisture sensitivity using a Hamburg Wheel Tracking Device. The binder was extracted from the field mixtures with varying amounts of RAP materials and tested to determine the effects of RAP materials on the PG grade of a virgin binder. Field cores were taken from the various mix designs to determine the percent density of each test section. A condition survey of the test sections was then performed to evaluate the short-term performance.

Although evidence is mounting that asphalt binder oxidizes in pavements, and that oxidation and subsequent hardening of asphalt binder has a profound effect on pavement durability, important implementation issues remain to be better understood. Quantitative assessment of asphalt binder oxidation for a given pavement is a very important, but complex issue. In this dissertation, a fundamentals-based oxygen transport and reaction model was developed to assess quantitative asphalt binder oxidation in pavements. In this model, oxygen transport and reaction were described mathematically as two interlinked steps: 1) diffusion and/or flow of oxygen from the atmosphere above the pavement into the interconnected air voids in the pavement; and 2) diffusion of oxygen from those air voids into the adjoining asphalt-aggregate matrix where it reacts with the asphalt binder. Because such a model calculation depends extensively on accurately representing pavement temperature, understanding oxygen diffusivity in asphalt binders and mastics, and characterizing air voids in pavements, these key model elements were studied in turn. Hourly pavement temperatures were calculated with an improved one-dimensional heat transfer model, coupled with methods to obtain model-required climate data from available databases and optimization of site-specific pavement parameters nationwide; oxygen diffusivity in binders was determined based on laboratory oxidation experiments in binder films of known reaction kinetics by comparing the oxidation rates at the binder surface and at a solid-binder interface at the film depth. The effect of aggregate filler on oxygen diffusivity also was quantified, and air voids in pavements were characterized using X-ray computed tomography (X-ray CT) and image processing techniques. From these imaging techniques, three pavement air void properties, radius of each air void (r), number of air voids (N), and average shell distance between two air voids (rNFB) were obtained to use as model inputs in the asphalt binder oxidation model. Then, by incorporating these model element improvements into the oxygen transport and reaction model, asphalt binder oxidation rates for a number of Texas and Minnesota pavements were calculated. In parallel, field oxidation rates were measured for these corresponding pavement sites and compared to the model calculations. In general, there was a close match between the model calculations and field measurements, suggesting that the model captures the most critical elements that affect asphalt binder oxidation in pavements. This model will be used to estimate the rate of asphalt binder oxidation in pavements as a first step to predicting pavement performance, and ultimately, to improve pavement design protocols and pavement maintenance scheduling.

Planning road maintenance and development activities, prioritizing road construction, reconstruction and rehabilitation works, performing project economic evaluations, forecasting road operation expenditures and road user effect always requires prediction of pavement behaviour. For this purpose models of pavement deterioration are used. Commonly they are integrated in more sophisticated computational systems, known as Pavement Management systems (PMS) and Highway Development and Management systems (HDM). The implementation of these systems started in Lithuania shortly after the Re-establishment of the Independence. This was triggered by the violent drop in financing of the road sector, forcing to change obsolete road management strategy and planning approach. The need for project economic evaluations, transport modelling and long term pavement performance forecasts grew up after Lithuania joined the European Union and this brought the opportunity for financing road infrastructure projects from the EU funds. At present only on the Lithuanian state road network the total value of implemented projects, justified by evaluations and modelling with PMS, amounts to about 500 million Litas annually. Any Pavement Management System is just as good as the models within it, used for pavement deterioration prediction. The performed test calculations show that prediction models, currently used for this purpose in PMS we have in Lithuania, are of doubtful accuracy and have to be improved.

Baigiamajame magistro darbe pateikta mokslo darbų, skirtų vėžių atsiradimo, gilėjimo asfalto dangoje ir įtakos transporto priemonių važiavimui analizė. Pateikti vėžių asfalto dangoje dinamikos ir įtakos transporto priemonių važiavimui modeliai. Atlikti Provėžų gylio pasiskirstymo Lietuvos valstybinės reikšmės magistraliniuose bei krašto keliuose eksperimentiniai tyrimai. Suformuluotos ir pateiktos išvados ir siūlymai. / The Master thesis provides the analysis of scientific works on the origin of ruts, their deepening on the asphalt pavement and impact on the vechile drive. It presents models of the dynamics of ruts on the asphalt pavement and their impact on the vehicle drive. Morover, experimental researches of the distribution of the depth of ruts on Lithuanian main and national roads were carried out, conclusions and suggestions formed and provided.

Low temperature cracking is a major distress in asphalt pavements. Several test configurations have been introduced to characterize the fracture properties of hot mix (HMA); however, most are considered to be research tools due to the complexity of the test methods or equipment. This dissertation describes the development of the indirect ring tension (IRT) fracture test for HMA, which was designed to be an effective and user-friendly test that could be deployed at the Department of Transportation level. The primary advantages of this innovative and yet practical test include: relatively large fracture surface test zone, simplicity of the specimen geometry, widespread availability of the required test equipment, and ability to test laboratory compacted specimens as well as field cores. Numerical modeling was utilized to calibrate the stress intensity factor formula of the IRT fracture test for various specimen dimensions. The results of this extensive analysis were encapsulated in a single equation. To develop the test procedure, a laboratory study was conducted to determine the optimal test parameters for HMA material. An experimental plan was then developed to evaluate the capability of the test in capturing the variations in the mix properties, asphalt pavement density, asphalt material aging, and test temperature. Five plant-produced HMA mixtures were used in this extensive study, and the results revealed that the IRT fracture test is highly repeatable, and capable of capturing the variations in the fracture properties of HMA. Furthermore, an analytical model was developed based on the viscoelastic properties of HMA to estimate the maximum allowable crack size for the pavements in the experimental study. This analysis indicated that the low-temperature cracking potential of the asphalt mixtures is highly sensitive to the fracture toughness and brittleness of the HMA material. Additionally, the IRT fracture test data seemed to correlate well with the data from the distress survey which was conducted on the pavements after five years of service. The maximum allowable crack size analysis revealed that a significant improvement could be realized in terms of the pavements performance if the HMA were to be compacted to a higher density. Finally, the IRT fracture test data were compared to the results of the disk-shaped compact [DC(t)] test. The results of the two tests showed a strong correlation; however, the IRT test seemed to be more repeatable.

Master of Science / Civil Engineering / Mustaque A. Hossain / Approximately 89% of 11,000 miles of Kansas roads are surfaced with asphalt. Hundreds of thousands of tons of reclaimed asphalt pavement (RAP) are produced annually in the United States, including in Kansas. This bulk volume of RAP must be economically managed in order to achieve environmental friendliness. Recycling of RAP conserves natural resources and reduces landfill usage. However, many agencies have reported that increased RAP content produces drier hot-mix asphalt (HMA) mixtures than virgin mixtures that are susceptible to premature cracking. In this research, laboratory-produced Superpave HMA mixtures containing increased percentages (20, 30, and 40%) of RAP materials from three RAP sources (Shilling Construction Co., Konza Co., and the Kansas Department of Transportation’s project, US 73) were studied for cracking performance. Mix designs were produced using Superpave design criteria for 12.5-mm nominal maximum aggregate size mixture. The static and repetitive Semicircular Bending (SCB) test, the Texas Overlay Tester test, the dynamic modulus test, and Viscoelastic Continuum Damage (VECD) tests were performed on laboratory-prepared samples. In general, cracking performance decreased with increased RAP content. The RAP from the US 73 project performed most consistently compared to other two sources of RAPs. Test results were analyzed using two-way Analysis of Variance (ANOVA), proving that mixtures containing 4.5% to 4.9% binder performed the best against cracking. The RAP source was found to have more effect on cracking propensity than RAP content. Mixtures with RAP content up to 40% performed satisfactorily. Tukey’s pairwise comparison method was used to compare results from all tests; VECD was determined to be the most appropriate test to evaluate cracking propensity of HMA mixtures.

abstract: Use of Recycled Asphalt Pavement (RAP) in newly designed asphalt mixtures is becoming a common practice. Depending on the percentage of RAP, the stiffness of the hot mix asphalt (HMA) increases by incorporating RAP in mixes. In a climatic area such as the City of Phoenix, RAP properties are expected to be more oxidized and aged compared to other regions across the US. Therefore, there are concerns about the cracking behavior and long-term performance of asphalt mixes with high percentage of RAP. The use of Organosilane (OS) in this study was hypothesized to reduce the additional cracking potential and improve resistance to moisture damage of the asphalt mixtures when using RAP. OS has also the potential to improve the bond between the aggregate and asphalt binder. The use of OS also reduces the mixing and compaction temperatures required for asphalt mixtures, making it similar to a warm mix asphalt (WMA), Six asphalt mixes were prepared with three RAP contents, 0%, 15% and 25%, with and without Organosilane. The mixing temperature was reduced by 10°C and the compaction temperature was reduced by 30°C. Mix designs were performed, and the volumetric properties were compared. The mixture laboratory performance was evaluated for all mixtures by conducting Dynamic Modulus, Flow Number and Tensile Strength Ratio tests. The study findings showed that mixtures achieved better compaction at a reduced temperature of 30°C. Mixtures modified with Organosilane generally exhibited softer behavior at the extreme ends of lower and higher temperatures. The lower moduli are to reduce the potential for cracking. For the Flow Number test, the RAP mixtures with OS passed the minimum required at all traffic levels. Tensile Strength Ratio results increased with the increase in RAP percentage, and further increase was observed when OS was used. The OS reduced the sticking nature of the binder to the molds and equipment, which reduced the efforts in cleaning them. Finally, the future use of RAP by the City of Phoenix would positively contributes to their sustainability aspiration and initiatives. The use of Organosilane may even facilitates higher percentage of RAP usage; it definitely improves the moisture resistance of asphalt mixtures, especially when lower mixing and compaction temperatures are desired or used. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2018

Este trabalho apresenta um estudo focado na implementação de metas de manutenção funcional de pavimentos flexíveis aeroportuários de pistas de pouso e decolagem. Os aeroportos além de terem que desempenhar sua função conforme especificado pela Agência Nacional de Aviação Civil (ANAC), devem também preservar os pavimentos existentes em boas condições e promover segurança e conforto ao usuário. Ainda que haja critérios para definição de estratégias de manutenção dos pavimentos para as pistas de pouso e decolagem em outros países, é recomendado para o caso de aeroportos no Brasil a consideração de outros parâmetros relacionados a patologias e bacias transversais na superfície do pavimento. O objetivo desse trabalho é propor metas para uma manutenção efetiva para avaliação funcional de pavimentos aeroportuários flexíveis e com esse intuito, foram feitos levantamentos bibliográficos referentes a avaliação funcional, principais patologias encontradas em pavimentos flexíveis, avaliação de segurança em pavimentos aeroportuários, levantamento do índice de irregularidade internacional (IRI), principais índices de avaliação funcional e sistemas de gerenciamento de pavimentos utilizados no Brasil e em alguns países, e um estudo de caso para definição de parâmetros importantes adaptados à realidade brasileira para a criação de metas de manutenção. Para o estudo de campo foram realizados levantamentos nas pistas de pouso e decolagem de quatro aeroportos regionais no Estado de São Paulo. Os levantamentos realizados foram defeitos/patologias existentes na pista, irregularidade longitudinal e bacias transversais da pista. Para o levantamento da irregularidade longitudinal e bacias transversais na pista foi utilizado o equipamento Planógrafo AX 02, enquanto os defeitos foram levantados de acordo com a regulamentação americana do FAA (Federal Aviation Administration) para determinação do PCI (Pavement Condition Index) de acordo com o procedimento da norma ASTM D5340 (2012). / This paper presents a study focused on the implementation of functional maintenance targets for airport runway flexible pavement. Airports besides performing its function specified by the Brazilian National Civil Aviation Agency (ANAC), should also preserve existing pavements in good condition and promote safety and comfort to the passenger. Although there are already criteria to define pavement maintenance strategies for runways in other countries, it is recommended for the Brazilian airports to consider other parameters related to pathologies and transversal basins on the pavement surface. This research consists on establishing an effective maintenance for functional evaluation of flexible runway pavement. Once established the purpose a literature review aiming to study the functional evaluation in flexible pavements was performed. The references also include main distresses found in asphalt pavements, safety evaluation on runway pavements, the International Roughness Index (IRI), the main functional evaluation indexes and Airport Pavement Management Systems in Brazil and in worldwide, and a case study to define important maintenance parameters adapted to Brazilian runways. The survey in loco was carried out to collect information about the runway state of four regional airports. This inspection detected irregularities along the runway and failure in the cross-section profile by the Planograph AX 02 equipament, and also revealed pavement defects pathologies according to the Federal Aviation Administration (FAA) regulations to determine the Pavement Condition Index (PCI), ASTM D5340 (2012).

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-08-05T13:16:00Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação Armando Muchanga.pdf certa.pdf: 9213756 bytes, checksum: e7f44528d62ad3cf348371353e3934a6 (MD5) / Made available in DSpace on 2016-08-05T13:16:00Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação Armando Muchanga.pdf certa.pdf: 9213756 bytes, checksum: e7f44528d62ad3cf348371353e3934a6 (MD5) Previous issue date: 2016-02-01 / CNPq / O desenvolvimento urbano depende de vários setores, e o mais importante, além de mais caro nos custos de urbanização é o setor de infraestrutura de transporte, responsável pela pavimentação e manutenção das vias. Com o aumento acelerado de veículos que trafegam nas vias, para um departamento de transporte manter uma rede viária urbana sob os níveis de desempenho requeridos ao longo da vida útil do pavimento é necessário que haja um melhor gerenciamento das atividades de manutenção. De todos os tipos de defeitos dos pavimentos, os que mais preocupam os usuários das vias, gestor e os técnicos da manutenção são os buracos. Alinhada a este fato exposto, esta dissertação propõe um modelo Delay Time para determinar o período ótimo de inspeção e manutenção preventiva dos pavimentos asfálticos urbanos, em particular das vias da cidade de Recife, de modo a minimizar os custos de manutenção. Primeiro são exploradas as abordagem de modelo Delay Time, para analisar a que se adequa aos pavimentos asfáltico. E a abordagem proposta é Delay Time do sistema complexo, sujeito a várias falhas, com inspeção perfeita e taxa de chega de defeitos homogênea. Os pavimentos são sujeitos a vários tipos de defeitos, mas este trabalho considerou os buracos por serem os defeitos que mais gastam no custo de manutenção. Também é feita uma revisão dos trabalhos que contribuíram para investigação e aplicação do modelo Delay Time. Ainda neste trabalha é apresentado uma revisão das normas dos pavimentos asfáltico, bem como a politica de manutenção “Operação Tapa-Buraco” praticada atualmente nas vias da cidade de Recife para tapar os buracos. O modelo proposto mostra se viável e não é sensível quando variam os parâmetros de entra, os resultados obtidos são fáceis de aplicar se o setor de manutenção de pavimento da cidade de Recife incluir as hipóteses do modelo na “Operação Tapa-Buraco”. / The urban development depends on several sectors, the most important, beyond most expensive, comes from the transport infrastructure sector - that is responsible for paving and maintenance of roads. Due the rapid increase of vehicles on roads, for the transport department to keep an urban road network under the performance levels required it is necessary to invest in a better management of maintenance activities. Among all types of floors of defects, the primary concern to road users, managers and maintenance technicians are the holes. In sum to this stated fact, this dissertation proposes a Delay Time model to determine the optimal period of inspection and preventive maintenance of urban asphalt pavements, particularly for the roads of the city of Recife, in order to minimize maintenance costs. First it was explored the Delay Time model approach to analyse which applies to the asphalt pavements. The proposed approach is Delay Time of complex system, subject to several failures, with perfect inspection and a homogeneous rate of defects arrival. Besides the floors being subject to various types of defects, this work only considers holes as defects that cause more impact on the maintenance cost. It is also made a review of the works that contributed to research and application of Delay Time Models. Also in this work is presented a review of the standards of asphalt pavements, as well as the maintenance policy "Operação Tapa-Buraco", currently practiced in Recife city roads to slap the holes. The proposed model shows that it is viable and is not sensitive when varying input parameters, the results are easy to apply to the Recife city pavement maintenance industry including the model assumptions in "Operação Tapa-Buraco".