Two differently structured food webs can be distinguished in the pelagic habitat of aquatic systems; the classical one (autotrophic) with phytoplankton as a base and the microbial food web (heterotrophic) with bacteria as a base. Energy (produced at the basal trophic level) reaches higher trophic levels, i.e. zooplankton, directly in the classical food web in contrast to the microbial food web where it passes through additional trophic levels before reaching zooplankton. Energy is lost between each trophic level and therefore less energy should reach higher trophic levels in the microbial food web than in the classical food web. However, factors such as edibility of prey, temperature and properties of the predator, might also influence the food web structures and functions. In this thesis I studied which factors are important for an efficient carbon transfer and how a potential climate change might alter the food web efficiency in pelagic and pelagic-benthic food webs in the Baltic Sea. Furthermore, one of the most dominant zooplankton in the northern Baltic Sea, Limnocalanus macrurus, was studied in order to establish the seasonal pattern of lipid reserves in relation to food consumption. My studies showed that the carbon transfer efficiency during summer was not directly connected to the basal production, but factors such as the ratio between heterotrophs and autotrophs, the relationship between cladocerans and calanoid copepods and the size and community structure of both phytoplankton and zooplankton were important for the carbon transfer efficiency. In a climate change perspective, the temperature as well as the relative importance of the microbial food web is likely to increase. A temperature increase may have a positive effect on the pelagic food web efficiency, whereas increasing heterotrophy will have a negative effect on the pelagic and pelagic-benthic food web efficiency, reduce the fatty acid content of zooplankton and reduce the individual weight of both zooplankton and the benthic amphipod Monoporeia affinis. During the seasonal study on the calanoid copepod L. macrurus, I found that this species is mainly a carnivore, feeding on mesozooplankton during most of the year but switches to feeding on phytoplankton when these are abundant. Furthermore, when food is scarce, it utilizes lipids that are built up during the course of the year. From these studies I can draw some major conclusions; there are many factors that influence how efficient carbon is transferred in the food web and different factors are probably of various importance in different areas. In order to determine the carbon transfer efficiency, the various strategies exerted by different organism groups have to be considered, as for example that some zooplankton utilize lipid reserves instead of feeding all year around. Also, in a climate change perspective, the pelagic-benthic food web efficiency will decrease, as will the quality of zooplankton and M. affinis, possibly having implications for higher trophic levels such as fish.

Concrete pavements are a suitable alternative for high-traffic volume roads, concentrated loads and roads exposed to severe weather conditions. In Sweden, among other reasons, the scarcity of concrete pavements is attributed to the need for more national knowledge and expertise in the field. The most recent concrete pavement was constructed seventeen years ago in Uppsala. Concrete pavements are renowned for their longevity and durability. Jointed plain concrete pavements (JPCP) are the most frequent type of concrete pavements. However, it is important to note that the joints in concrete pavements are critical components that can lead to various distresses, necessitating rehabilitation. Rehabilitating concrete pavements is particularly challenging in areas with heavy traffic and requires substitute routes because of the imperative to maintain traffic flow during construction. Developing effective detours might involve significant alterations to the existing routes or building temporary roads, which entails substantial cost investment and time consumption. A literature review has been conducted to study the available methods that can be used to repair concrete pavements. The strategy for selecting a repair technique is based on rehabilitating the concrete pavement within a short work window, deterring traffic congestion and ensuring the long service life of the pavements. The study showed that the precast concrete technology based on the precast slab is a promising technology that effectively shortens the lane closure for repairing damaged pavements and produces durable pavements, thereby extending the service life of pavements. However, the construction or rehabilitation cost of concrete pavement using precast slabs is 1.6 to 4 times higher than that of conventional cast-in-place concrete. Therefore, rehabilitation using precast slabs is inappropriate for low-traffic roads and temporary routes. Joints are crucial for the rehabilitation of concrete pavements with precast slabs. The structural performance of concrete pavement is, however, greatly affected by the joints, as the presence of joints creates a discontinuity between adjacent slabs and thus diminishes the load transfer to the abutting slab. To maintain the structural integrity of the pavement system, dowel bars are used at the transverse joints. A numerical study has been conducted to evaluate the influence of various dowel-related parameters on the interaction between adjacent concrete slabs. The study revealed that the dowel bar’s position, mislocation and diameter had an obvious effect on joint efficiency, while the bond between the concrete slab and the dowel bar slightly affected the load transfer efficiency. It was also investigated that the dowel bar’s intended performance, i.e., load transfer efficiency, was reduced as the joint gap between adjacent slabs increased. / Betongbeläggningar är ett lämpligt alternativ för högtrafikerade vägar, koncentrerad belastning och vägar utsatta för svåra väderförhållanden. I Sverige är betongvägar sällsynta vilket bl.a. beror på brist på kunskap och kompetens. Den senaste betongvägen byggdes för sjutton år sedan i Uppsala.Betongbeläggningar är kända för sin långa livslängd och hållbarhet. Den vanligaste typen av betongvägar är fogade, oarmerade betongbeläggningar. Ändå är det viktigt att notera att fogarna i betongbeläggningar är kritiska komponenters om kan leda till olika olägenheter, vilket kräver rehabilitering. Att rehabilitera betongbeläggningar är särskilt utmanande i områden med intensiv trafik som kräver ersättningsvägar på grund av nödvändigheten att upprätthålla trafikflödet under reparationsarbetena. Att ta fram en effektiv omledning av trafiken kan innebära antingen väsentliga förändringar och förlängningar av befintliga rutter eller byggande av tillfälliga vägar, vilket medför betydande kostnadsinvesteringar och tidsåtgång. En litteraturöversikt har genomförts för att studera de tillgängliga metoderna som kan användas för att reparera betongbeläggningar. Strategin för valet av reparationsmetod bygger på att rehabilitera betongbeläggningen inom ett kort arbetsfönster, förhindra trafikstockningar och säkerställa lång livslängd för beläggningen. Studien visade att förtillverkade betongplattor är en lovande metod som effektivt förkortar avstängningen av körfält för att reparera skadad beläggning och producerar hållbara betongbeläggningar med lång livslängd. Rehabiliterings kostnaden för betongbeläggning med prefabricerade plattor är emellertid 1,6 till 4 gånger högre än den för konventionell platsgjuten betong. Därför är rehabilitering med förtillverkade betongplattor olämplig för vägar med låg trafik och temporära rutter. Fogar är vidare nödvändiga vid reparation med förtillverkade betongplattor.Betongbeläggningens strukturella prestanda påverkas dock kraftigt av fogar, eftersom förekomsten av fogar skapar en diskontinuitet mellan intilliggande plattor och därmed minskat lastöverföringen till den angränsande plattan. För att upprätthålla den strukturella integriteten hos beläggningssystemet används dymlingar i de tvärgående fogar. En numerisk studie har genomförts med olika parametrar för att utvärdera dymlingens inverkan på fogens effektivitet. Studien visade att dymlingens position, felplacering och diameter har en tydlig inverkan på fogens effektivitet, medan vidhäftningen mellan dymling och betongplatta enbart verkar ha en marginell inverkan på fogens effektivitet. Studien visade också att dymlingens prestanda, dvs. lastöverföringsförmågan, minskade då fogöppningen eller glappet mellan två närliggande plattor ökade. / <p>QC 240207</p>

No description available.

Marine oils are used as ration additives to provide omega-3 fatty acids to dairy cows. Supplementing dairy cows with omega-3 fatty acid-rich feeds does not easily increase quantities in milk fat of dairy cows because polyunsaturated fatty acids are biohydrogenated in the rumen. Lipid encapsulation of omega-3 fatty acids provides protection from biohydrogenation in the rumen and allows them to be available for absorption and utilization in the small intestine. Lactating cows were supplemented with rumen protected algae biomass or algal oil in a 4 × 4 Latin Square. Feeding lipid encapsulated algae supplements increased docosahexaenoic acid content in milk fat while not adversely impacting milk fat yield; however, docosahexaenoic acid was preferentially esterified into plasma phospholipid, limiting its incorporation into milk fat. In the second study, triglyceride emulsions of oils enriched in either oleic, linoleic, linolenic, or docosahexaenoic acids were intravenously infused to avoid confounding effects of triglyceride esterification patterns in the small intestine and to compare mammary uptake. Milk transfer of fatty acids delivered as intravenous triglyceride emulsions was reduced with increased chain length and unsaturation. Increased target fatty acids were evident in plasma phospholipid, suggesting re-esterification in the liver. Transfer efficiencies were 37.8, 27.6, and 10.9±5.4% for linoleic, linolenic, and docosahexaenoic acid. Both liver and mammary mechanisms may regulate transfer of long-chain polyunsaturates. Intracellular fatty acid binding proteins (FABP) are cytoplasmic proteins that are hypothesized to be essential for fatty acid transport and metabolism by accelerating longchain fatty acid uptake and targeting to intracellular organelles, such as the endoplasmic reticulum for triglyceride esterification. FABP3 mRNA is highly expressed in bovine mammary and heart tissue, but is not present in MAC-T cells, a bovine mammary epithelial cell line. When overexpressed in MAC-T cells, FABP3 does not appear to be rate-limiting for fatty acid uptake in vitro and did not alter lipid metabolism. The function of FABP3 in the mammary gland remains unclear. / Ph. D.

Achieving energy neutrality has shifted focus towards aeration systems optimization, due to the high energy consumption of aeration processes in modern advanced wastewater treatment plants. The activated sludge wastewater treatment process is dependent on aeration efficiency which supplies the oxygen needed in the treatment process. The process is a complex heterogeneous mixture of microorganisms, bacteria, particles, colloids, natural organic matter, polymers and cations with varying densities, shapes and sizes. These activated sludge parameters have different impacts on aeration efficiency defined by the OTE, % and alpha. Oxygen transfer efficiency (OTE) is the mass of oxygen transferred into the liquid from the mass of air or oxygen supplied, and is expressed as a percentage (%). OTE is the actual operating efficiency of an aeration system. The alpha Factor (α) is the ratio of standard oxygen transfer efficiency at process conditions (αSOTE) to standard oxygen transfer efficiency of clean water (SOTE). It is also referred to as the ratio of process water volumetric mass transfer coefficient to clean water volumetric mass transfer coefficient. The alpha factor accounts for wastewater contaminants (i.e. soap and detergent) which have an adverse effect on oxygen transfer efficiency. Understanding their different impacts and how different treatment technologies affect aeration efficiency will help to optimize and improve aeration efficiency so as to reduce plant operating costs. A pilot scale study of fine pore diffuser fouling and mitigation, quantified by dynamic wet pressure (DWP), oxygen transfer efficiency and alpha measurement were performed at Blue Plains, Washington DC. In the study a mechanical cleaning method, reverse flexing (RF), was used to treat two diffusers (RF1, RF2) to mitigate fouling, while two diffusers were kept as a control with no reverse flexing. A 45 % increase in DWP of the control diffuser after 17 month of operation was observed, an indication of fouling. RF treated diffusers (RF1 and RF2) did not show any significant increase in DWP, and in comparison to the control diffuser prevented a 35 % increase in DWP. Hence, the RF fouling mitigation technique potentially saved blower energy consumption by reducing the pressure burden on the air blower and the blower energy requirement. However, no significant impact of the RF fouling mitigation treatment technique in preventing a decrease in alpha-fouling (𝝰F) of the fine pore diffusers over time of operation was observed. This was because either the RF treatment method maintained wide pore openings after cleaning over time, or a dominant effect of other wastewater characteristics such as the surfactant concentration or particulate COD could have interfered with OTE. Further studies on the impact of wastewater characteristics (i.e., surfactants and particulate COD) and operating conditions on OTE and alpha were carried out in another series of pilot and batch scale tests. In this study, the influence of different wastewater matrices (treatment phases) on oxygen transfer efficiency (OTE) and alpha using full-scale studies at the Blue Plains Treatment Plant was investigated. A strong relationship between the wastewater matrices with oxygen transfer characteristics was established, and as expected increased alphas were observed for the cleanest wastewater matrices (i.e., with highest effluent quality). There was a 46 % increase in alpha as the total COD and surfactant concentrations decreased from 303 to 24 mgCOD/L and 12 to 0.3 mg/L measured as sodium dodecyl sulphate (SDS) in the nitrification/denitrification effluent with respect to the raw influent. The alpha improvement with respect to the decrease in COD and surfactant concentration suggested the impact of one or more of the wastewater characteristics on OTE and alpha. Batch testing conducted to characterize the mechanistic impact of the wastewater contaminants present in the different wastewater matrices found that the major contaminants influencing OTE and alpha were surfactants and particulate/colloidal material. The volumetric mass transfer coefficient (kLa) measurements from the test also identified surfactant and colloidal COD as the major wastewater contaminants present in the influent and chemically enhanced primary treatment (CEPT) effluent wastewaters impacting OTE and alpha. Soluble COD was observed to potentially improve OTE and alpha due to its contribution in enhancing the oxygen uptake rate (OUR). Although the indirect positive impact of OUR on alpha observed in this study contradicts some other studies, it shows the need for further investigation of OUR impacts on oxygen transfer. Importantly, the mechanistic characterization and quantitative correlation between wastewater contaminants and aeration efficiency found in this study will help to minimize overdesign with respect to aeration system specification, energy wastage, and hence the cost of operation. This study therefore shows new tools as well as the identification of critical factors impacting OTE and alpha in addition to diffuser fouling. Gas transfer depression caused by surfactants when they accumulate at the gas-liquid interface during the activated sludge wastewater treatment process reduces oxygen mass transfer rates, OTE and alpha which increases energy cost. In order to address the adverse effect of surfactants on OTE and alpha, another study was designed to evaluate 4 different wastewater secondary treatment strategies/technologies that enhances surfactant removal through enhanced biosorption and biodegradation, and to also determine their effect on oxygen transfer and alpha. A series of pilot and batch scale tests were conducted to compare and correlate surfactant removal efficiency and alpha for a) conventional high-rate activated sludge (HRAS), b) optimized HRAS with contactor-stabilization technology (HRAS-CS), c) optimized HRAS bioaugmented (Bioaug) with nitrification sludge (Nit S) and d) optimized bioaugmented HRAS with an anaerobic selector phase technology (An-S) reactor system configuration. The treatment technologies showed surfactant percentage removals of 37, 45, 61 and 87 %, and alphas of 0.37 ±0.01, 0.42 ±0.02, 0.44 ±0.01 and 0.60 ±0.02 for conventional HRAS, HRAS-CS, Bioaug and the An-S reactor system configuration, respectively. The optimized bioaugmented anaerobic selector phase technology showed the highest increased surfactant removal (135 %) through enhanced surfactant biosorption and biodegradation under anaerobic conditions, which also complemented the highest increased alpha (62 %) achieved when compared to the conventional HRAS. This study showed that the optimized bioaugmented anaerobic selector phase reactor system configuration is a promising technology or strategy to minimize the surfactant effects on alpha during the secondary aeration treatment stage / Ph. D. / In the activated sludge process, the energy requirement for aeration which also includes nitrogen removal is a major operating expense for utilities, and it has limited the ability of most water and wastewater reclamation facilities to achieve energy neutrality. Aeration has therefore become one of the most energy and capital intensive aspects of wastewater treatment. There are still knowledge gaps and mechanistic understanding of the impact of wastewater characteristics and treatment processes on aeration efficiency, which past and current studies are yet to provide. Aeration efficiency is defined by oxygen transfer efficiency and alpha (an indicator of wastewater contaminant effect on aeration efficiency). This study provided an insight into important wastewater characteristics, treatment processes and operational parameters contributing to aeration cost. An understanding of the impacts of wastewater characteristics and how different treatment technologies affect aeration efficiency as discussed in this study will help design engineers and operators to optimize and improve aeration efficiency, so as to reduce plant operating costs. The first study objective on fine bubble diffuser fouling dynamics and physical treatment method quantified by dynamic wet pressure (DWP), oxygen transfer efficiency and alpha measurement was carried out in a pilot reactor. DWP quantified the fouling dynamics of fine pore diffusers. A diffuser fouling physical treatment (reverse flexing, RF) method was able to mitigate fouling of the fine pore diffusers by preventing an increase in DWP normally observed in fouled fine pore diffusers. The RF treatment method reduced fouling by 35 % as compared to the control diffuser (without reverse flexing). This will reduce the pressure burden and air blower energy requirement. The second study objective evaluated the impact of different wastewater characteristics and removal in different stages on aeration efficiency. Test results in this study showed that surfactant and particulate COD fractions were the major characteristics constituents contained in wastewater that depressed aeration efficiency defined by OTE and alpha. Soluble COD did not show any inhibiting effect on OTE and alpha. The third study objective evaluated three different optimized wastewater treatment technologies of surfactant removal during aeration treatment process; 1) High rate activated sludge (HRAS) with contactor-stabilization technology (The contactor stabilization process) (HRAS-CS); 2) HRAS bioaugmented (BioAug) with nitrification sludge (Nit S); and 3) Bioaugmented HRAS with an anaerobic selector phase (An-S) configuration. All three technologies increased surfactant removal through enhanced biosorption and biodegradation to various degrees when compared the conventional high rate activated sludge treatment, but the An-S treatment technology achieved the highest surfactant removal and alpha improvement. The study also established the optimum performance process conditions for each optimized treatment technology.

Crustaceans, the most abundant group of organisms that make up zooplankton, form a critical link in the food web between primary-producing phytoplankton and planktivorous fish. Examining this link is essential in order to effectively estimate the amount of energy available to higher trophic levels. The most appropriate currency for tracking energy flow through these food webs is to measure production, or the amount of new biomass generated over a given period of time. Although measurements of primary productivity are routinely made in oceanographic studies, estimates of secondary productivity are rare due to their historical reliance on time-consuming methods. The overall objective of this thesis was to determine the factors influencing temporal variations in community-level crustacean productivity. A simplified lab experiment was used to establish a relationship between diet and chitobiase-based estimates of copepod productivity in response to single versus mixed species phytoplankton diets. In addition, the relationships between primary productivity and chitobiase-based productivity for the entire crustacean zooplankton community were examined over two years in Saanich Inlet, British Columbia, Canada. Lastly, this work determined the abiotic and biotic factors most strongly influencing crustacean productivity in the tropical Guanabara Bay, Rio de Janeiro, Brazil, dominated by the microbial loop. Results from this work show that: (i) copepod populations fed a poor food item take longer to develop through early stages, have lower daily growth rates, and exhibit lower productivity than those fed a good quality food item; (ii) important variations in crustacean productivity are missed when biomass estimates, alone, are used to represent food available to higher trophic levels; (iii) relationships between primary productivity and crustacean productivity can vary interannually and are not necessarily controlled by bottom-up processes; (iv) substantial interannual variations in trophic transfer efficiency (TTE) occur even if average TTE is the same across years; and (v) community-level crustacean productivity in tropical regions dominated by the microbial food loop can be as high as, if not higher than, productivity measured in temperate regions. Ultimately, this work provides insight into how accurate productivity estimates can improve our understanding of zooplankton dynamics in both laboratory and field settings in marine ecosystems worldwide. / Graduate

This dissertation details the development and experimental implementation of single-photon atomic cooling. In this scheme atoms are transferred from a large-volume magnetic trap into a small-volume optical trap via a single spontaneous Raman transition that is driven near each atom's classical turning point. This arrangement removes nearly all of an atomic ensemble's kinetic energy in one dimension. This method does not rely on a transfer of momentum from photon to atom to cool. Rather, single-photon atomic cooling achieves a reduction in temperature and an increase in the phase-space density of an atomic ensemble by the direct reduction of the system's entropy. Presented here is the application of this technique to a sample of magnetically trapped ⁸⁷Rb. Transfer efficiencies between traps of up to 2.2% are demonstrated. It is shown that transfer efficiency can be traded for increased phase-space compression. By doing so, the phase-space density of a magnetically trapped ensemble is increased by a factor of 350 by the single-photon atomic cooling process. / text

No description available.

Os primeiros estudos sobre pavimentos de concreto continuamente armados (PCCA) foram desenvolvidos em zonas cujo clima característico é o temperado (EUA, Holanda e Bélgica), não se tendo estudos técnicos acerca do comportamento do pavimento em ambiente tropical. A premissa de funcionamento do PCCA está baseada na não execução de juntas de retração, obrigatórias em pavimentos de concreto simples (PCS), ou seja, as fissuras devido à retração do concreto ocorrem aleatoriamente, sendo controladas pela elevada taxa de armadura longitudinal disposta longitudinalmente ao longo de toda a extensão do pavimento. Como essa armadura não possui função estrutural, pois é colocada acima da linha neutra da placa, no banzo comprimido, sua função é manter as fissuras fortemente apertadas, garantindo suavidade ao rolamento e elevada transferência de carga (LTE), a qual ocorre pelo intertravamento dos agregados nas faces fissuradas, proporcionando assim um pavimento de alta durabilidade e que dispende baixíssimos custos com manutenção. No Brasil, a primeira experiência com PCCA teve início no ano de 2010, quando foram construídas quatro seções de 50 m de extensão cada, consideradas curtas em comparação aos 400 m de extensão de um PCCA rodoviário que podem ser alcançados ao final de um dia de trabalho. O monitoramento contínuo de tais seções mostrou haver uma diferença muito significativa de comportamento, comparado aos PCCA tradicionais, no que tange o tempo decorrido para estabelecimento do padrão de fissuração (a primeira fissura surgiu um ano após a construção), bem como espaçamento médio entre as fissuras, devido à curta extensão das placas e a inexistência de um sistema de ancoragem nas extremidades. Assim, para melhor compreender o comportamento de pavimentos de concreto com armadura contínua com padrões condizentes à realidade rodoviária em ambiente tropical, em janeiro de 2016, foi construído no campus da Universidade de São Paulo o primeiro PCCA de longa extensão do Brasil, com 200 m de comprimento. Foram empregados quatro diferentes tipos de concreto, variando o tipo de cimento e o tipo de agregado, bem como foram empregados aço galvanizado e aço comum. Para entender o comportamento do pavimento sob as condições climáticas brasileiras foram realizados três estudos: levantamento de fissuras (espaçamento e abertura), modelagem analítica do espaçamento entre fissuras através de modelos de previsão de retração em concreto e testes com FWD para avaliação da eficiência de transferência de carga (LTE) entre as fissuras. A análise do padrão de fissuração mostrou que o desenvolvimento das fissuras aconteceu conforme a literatura técnica, tendo início na primeira semana após a concretagem e atingindo aproximadamente 60% do número total de fissuras antes do primeiro mês. As seções centrais possuem o maior número de fissuras, pois estão ancoradas pelas seções de extremidade, onde o surgimento das fissuras é mais lento por conta da falta de ancoragem. As aberturas das fissuras mostraram-se maiores nas posições com aço galvanizado devido à menor aderência aço-concreto nesse caso, em comparação às posições com aço comum. O modelo de previsão de retração no concreto que melhor se aproximou do espaçamento médio desenvolvido em campo foi o modelo do Eurocode 2, com diferenças em torno de 30%, aproximadamente. As análises de LTE mostraram um desempenho muito satisfatório, apesar de a LTE nas regiões com aço galvanizado ter resultado menor do que a LTE nas regiões com aço comum. / The first studies on continuously reinforced concrete pavements (CRCP) were developed in areas in which the typical weather is temperate (United States, Netherlands and Belgium), with no technical studies carried out in tropical weather. CRCP structural premise is based on a slab without construction joints which are required in jointed plain concrete pavements (JPCP); i.e., CRCP cracks due to concrete shrinkage occur randomly being controlled by the high longitudinal reinforcement percentage, positioned longitudinally along the pavement length. As the longitudinal reinforcement has no structural role, because it is placed above the slab neutral axis, in the compression zone, its main function is to keep cracks strongly tight, ensuring a smooth ride and high load efficiency transfer (LTE) at cracks, which occurs through aggregates interlocking, thereby providing a highly durable pavement with low maintenance costs. The first experience with CRCP in Brazil started in 2010, when four experimental sections were constructed. Each section is 50 meters long, short when compared to the traditional CRCP that can extend for over 400 meters providing that concrete pouring does not stop. Continuous monitoring of these sections has shown that the short CRCP behaves differently from traditional CRCP, regarding the time taken for the cracking pattern full development (the first crack was visible on the surface one year after the construction), as well as average cracking space due to the slab\'s short extension and lack of anchorage. Therefore, in order to fully analyze the behavior of a traditional CRCP under tropical weather, in January 2016, the first long extension CRCP in Brazil was built, at the University of São Paulo campus, with 200 meters length. Four types of concrete were applied in the construction, varying cement and aggregate type. Galvanized and ordinary steel were used as well. To analyze the pavement behavior under Brazilian climatic conditions, three studies were carried out: cracks surveys (spacing and width), analytical modeling crack spacing through shrinkage prediction models and Falling Weight Deflectometer testing to evaluate the crack\'s load transfer efficiency (LTE). Cracking pattern analysis has shown cracks development consistent with technical literature. The first cracks appeared during the first week after concrete placement and, before the first month, about 60% of the total cracks number had developed. Central sections presented greatest number of cracks as they are anchored by the outer sections, where cracking occurs slower due to the lack of anchorage. Cracks width was higher in areas with galvanized steel due to the weaker steel-concrete bond, when compared to areas with common steel. The shrinkage prediction model for concrete that better approached the average field crack spacing was the Eurocode 2, with mean difference of 30%. LTE analysis has shown a quite satisfactory performance, even though LTE in areas with galvanized steel is lower than LTE in areas with common steel.

Os primeiros estudos sobre pavimentos de concreto continuamente armados (PCCA) foram desenvolvidos em zonas cujo clima característico é o temperado (EUA, Holanda e Bélgica), não se tendo estudos técnicos acerca do comportamento do pavimento em ambiente tropical. A premissa de funcionamento do PCCA está baseada na não execução de juntas de retração, obrigatórias em pavimentos de concreto simples (PCS), ou seja, as fissuras devido à retração do concreto ocorrem aleatoriamente, sendo controladas pela elevada taxa de armadura longitudinal disposta longitudinalmente ao longo de toda a extensão do pavimento. Como essa armadura não possui função estrutural, pois é colocada acima da linha neutra da placa, no banzo comprimido, sua função é manter as fissuras fortemente apertadas, garantindo suavidade ao rolamento e elevada transferência de carga (LTE), a qual ocorre pelo intertravamento dos agregados nas faces fissuradas, proporcionando assim um pavimento de alta durabilidade e que dispende baixíssimos custos com manutenção. No Brasil, a primeira experiência com PCCA teve início no ano de 2010, quando foram construídas quatro seções de 50 m de extensão cada, consideradas curtas em comparação aos 400 m de extensão de um PCCA rodoviário que podem ser alcançados ao final de um dia de trabalho. O monitoramento contínuo de tais seções mostrou haver uma diferença muito significativa de comportamento, comparado aos PCCA tradicionais, no que tange o tempo decorrido para estabelecimento do padrão de fissuração (a primeira fissura surgiu um ano após a construção), bem como espaçamento médio entre as fissuras, devido à curta extensão das placas e a inexistência de um sistema de ancoragem nas extremidades. Assim, para melhor compreender o comportamento de pavimentos de concreto com armadura contínua com padrões condizentes à realidade rodoviária em ambiente tropical, em janeiro de 2016, foi construído no campus da Universidade de São Paulo o primeiro PCCA de longa extensão do Brasil, com 200 m de comprimento. Foram empregados quatro diferentes tipos de concreto, variando o tipo de cimento e o tipo de agregado, bem como foram empregados aço galvanizado e aço comum. Para entender o comportamento do pavimento sob as condições climáticas brasileiras foram realizados três estudos: levantamento de fissuras (espaçamento e abertura), modelagem analítica do espaçamento entre fissuras através de modelos de previsão de retração em concreto e testes com FWD para avaliação da eficiência de transferência de carga (LTE) entre as fissuras. A análise do padrão de fissuração mostrou que o desenvolvimento das fissuras aconteceu conforme a literatura técnica, tendo início na primeira semana após a concretagem e atingindo aproximadamente 60% do número total de fissuras antes do primeiro mês. As seções centrais possuem o maior número de fissuras, pois estão ancoradas pelas seções de extremidade, onde o surgimento das fissuras é mais lento por conta da falta de ancoragem. As aberturas das fissuras mostraram-se maiores nas posições com aço galvanizado devido à menor aderência aço-concreto nesse caso, em comparação às posições com aço comum. O modelo de previsão de retração no concreto que melhor se aproximou do espaçamento médio desenvolvido em campo foi o modelo do Eurocode 2, com diferenças em torno de 30%, aproximadamente. As análises de LTE mostraram um desempenho muito satisfatório, apesar de a LTE nas regiões com aço galvanizado ter resultado menor do que a LTE nas regiões com aço comum. / The first studies on continuously reinforced concrete pavements (CRCP) were developed in areas in which the typical weather is temperate (United States, Netherlands and Belgium), with no technical studies carried out in tropical weather. CRCP structural premise is based on a slab without construction joints which are required in jointed plain concrete pavements (JPCP); i.e., CRCP cracks due to concrete shrinkage occur randomly being controlled by the high longitudinal reinforcement percentage, positioned longitudinally along the pavement length. As the longitudinal reinforcement has no structural role, because it is placed above the slab neutral axis, in the compression zone, its main function is to keep cracks strongly tight, ensuring a smooth ride and high load efficiency transfer (LTE) at cracks, which occurs through aggregates interlocking, thereby providing a highly durable pavement with low maintenance costs. The first experience with CRCP in Brazil started in 2010, when four experimental sections were constructed. Each section is 50 meters long, short when compared to the traditional CRCP that can extend for over 400 meters providing that concrete pouring does not stop. Continuous monitoring of these sections has shown that the short CRCP behaves differently from traditional CRCP, regarding the time taken for the cracking pattern full development (the first crack was visible on the surface one year after the construction), as well as average cracking space due to the slab\'s short extension and lack of anchorage. Therefore, in order to fully analyze the behavior of a traditional CRCP under tropical weather, in January 2016, the first long extension CRCP in Brazil was built, at the University of São Paulo campus, with 200 meters length. Four types of concrete were applied in the construction, varying cement and aggregate type. Galvanized and ordinary steel were used as well. To analyze the pavement behavior under Brazilian climatic conditions, three studies were carried out: cracks surveys (spacing and width), analytical modeling crack spacing through shrinkage prediction models and Falling Weight Deflectometer testing to evaluate the crack\'s load transfer efficiency (LTE). Cracking pattern analysis has shown cracks development consistent with technical literature. The first cracks appeared during the first week after concrete placement and, before the first month, about 60% of the total cracks number had developed. Central sections presented greatest number of cracks as they are anchored by the outer sections, where cracking occurs slower due to the lack of anchorage. Cracks width was higher in areas with galvanized steel due to the weaker steel-concrete bond, when compared to areas with common steel. The shrinkage prediction model for concrete that better approached the average field crack spacing was the Eurocode 2, with mean difference of 30%. LTE analysis has shown a quite satisfactory performance, even though LTE in areas with galvanized steel is lower than LTE in areas with common steel.