Resumo: A retrorrefletividade das pinturas de demarcações horizontais permite a visibilidade da sinalização viária durante a noite, impactando diretamente a segurança da via. O Brasil emprega normas e requisitos mínimos internacionas que foram parcialmente adaptados para as condições do país. De maneira geral, tais adaptações reduziram os níveis de segurança exigidos por estes importantes dispositivos, fato que pode acarretar prejuízos à condição de segurança e conforto. A partir da avaliação ao longo de dois anos de três segmentos experimentais, um rodoviário e dois urbanos, com diferentes tipos de demarcações e materiais, buscou-se fazer uma análise crítica da pertinência da forma de avaliação normativa no Brasil, bem como estudar o impacto da chuva, do acúmulo de sujeira e da geometria dos retrorrefletômetros sobre o desempenho da sinalização horizontal. Como esperado, demarcações empregando material termoplástico apresentaram um desempenho superior àquelas com tinta acrílica. O efeito abrasivo da interação pneu-pavimento desgasta tais dispositivos, reduzindo o nú-mero de elementos retrorrefletivos (microesferas); entretanto, a combinação tráfego mais precipitação mostrou-se positiva por permitir a limpeza "natural" da sinalização. Para o trecho urbano, o efeito da sujeira foi tão prejudicial quanto à abrasão causada por veículos pesados. A análise da retrorrefletividade, obtida com diferentes geometrias, perante limites mínimos nacionais e internacionais, demonstrou que os índices mínimos de retrorrefletividade aplicados no Brasil são pouco exigentes, merecendo, portanto, serem rediscutidos para melhor atender aos quesitos de segurança viária.Palavras-chave: demarcação viária; retrorrefletividade; requisitos mínimos; retrorrefletômetro.Abstract: Horizontal markings retroreflectivity allows road night visibility, which directly impacts road safety. Brazil employs international standards and minimum retroreflectivity requirements that were partially adapted to the country conditions. In general, such adjustments reduced the security levels of these devices damaging road safety and comfort. From the evaluation of three experimental sections (one highway and two urban avenues) with different markings and materials, over two years, the Brazilian standard procedure was critically analyzed. Also, the impact of rainfall, dirt and retroreflectometer geometry on the horizontal markings performance was addressed. As expected, thermoplastic markings outperformed those with acrylic paint. The abrasive effect of the tire-pavement interaction outwears the markings, reducing the number of retroreflective elements (glass beads); however, the combination of traffic plus rainfall was positive for allowing a "natural" marking cleaning. For the urban section, the effect of dirt was as damaging as the abrasion caused by heavy vehicles. The analysis of retroreflectivity, obtained with different geometries, regarding national and international thresholds, showed that the retroreflectivity minimum levels applied in Brazil are ineffi...

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ResumoIn recent years, due to the destructive and unproductive character of pavement specimen extraction, pavement maintenance technology intensified the use of non-destructive techniques for pavement evaluation which resulted in the development of several devices and evaluation methods. This paper describes the use of technology based on low frequency ultrasonic tomography for evaluation of concrete pavement parameters. The equipment was applied in three experimental sections with different concrete pavements built at the University of Sao Paulo campus. The ultrasonic signal processing is given. The results analysis enables the efficient and reliable identification of thickness and reinforcement position within the concrete slab. Construction problems were evidenced in one of experimental sections with thickness deficiencies and reinforcement in a position below projected. Furthermore, the use of a novel concrete quality indicator was correlated with the presence of transverse cracks and alkali-silica reaction within the sections.

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Transverse crack pattern significantly affects performance of continuously reinforced concrete pavement (CRCP). However, field and modeled crack spacing are based on visual surveys of fully developed transverse cracks visible on the slab surface. Because of the difficulties in detecting incipient cracks in concrete slabs, the effect that such cracks may have on CRCP performance is not currently considered. To address this issue, this paper presents a non-destructive evaluation methodology based on an ultrasonic linear-array system for detection of incipient cracks in CRCP slabs. Two ultrasonic signal-processing techniques were used. First, the Hilbert Transform Indicator was used to identify the presence of damage in the concrete slab indicating potential crack locations. Then ultrasonic image reconstructions of these locations were used to further evaluate crack presence. The methodology was applied to four sections of an experimental short CRCP composed of 50-m long slabs – short in comparison to traditional CRCP. The locations of 58 potential incipient cracks were identified updating the short CRCP crack spacing; 10 of these incipient cracks were confirmed as surface-visible cracks in later visual surveys. Additionally, the methodology shows potential to detect undesired crack patterns such as cluster and Y-cracking before the cracks emerge on the slab surface.

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ResumoFour continuously reinforced concrete pavement (CRCP) sections were built at the University of São Paulo campus in order to analyze the pavement performance in a tropical environment. The sections short length coupled with particular project aspects made the experimental CRCP cracking be different from the traditional CRCP one. After three years of construction, a series of nondestructive testing were performed -Falling Weight Deflectometer (FWD) loadings -to verify and to parameterize the pavement structural condition based on two main properties: the elasticity modulus of concrete (E) and the modulus of subgrade reaction (k). These properties estimation was obtained through the matching process between real and EverFE simulated basins with the load at the slab center, between two consecutive cracks. The backcalculation results show that the lack of anchorage at the sections end decreases the E and k values and that the longitudinal reinforcement percentage provides additional stiffness to the pavement. Additionally, FWD loadings tangential to the cracks allowed the load transfer efficiency (LTE) estimation determination across cracks. The LTE resulted in values above 90 % for all cracks.Keywords: concrete pavement, consitnuous reinforcement, deflections, backcalculation, load transfer efficiency.Quatro seções experimentais de pavimento de concreto continuamente armado (PCCA) foram construídas no campus da Universidade de São Paulo com a finalidade de analisar o desempenho deste tipo de pavimento em clima tropical. A curta extensão das seções aliada a aspectos específicos de projeto fizeram com que o PCCA experimental apresentasse um padrão de fissuração bastante distinto dos PCCA tradicionais. Passados três anos da construção, realizou-se uma série de testes não destrutivos -aplicações de Falling Weight Deflectometer (FWD) -para verificar e parametrizar a condição estrutural do pavimento com base em dois fatores principais: o módulo de elasticidade do concreto (E) e o módulo de reação do subleito (k). A estimativa das propriedades foi obtida através da equiparação de bacias reais com bacias simuladas pelo programa EverFE para a carga aplicada no meio da placa formada por duas fissuras. Os resultados da retroanálise mostram que a falta de ancoragem no final das placas diminui os valores de E e k e que a porcentagem de armadura proporciona um adicional de rigidez ao pavimento. Adicionalmente, aplicações de carga tangenciais às fissuras possibilitaram a determinação da eficiência de transferência de carga (LTE) entre fissuras. A LTE resultou em valores acima de 90% para todas as fissuras.Palavras-chave: pavimento de concreto, armadura contínua, deflexões, retroanálise, eficiência de transferência de carga. L. S. SALLES a

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