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The loss of performance against fatigue is evident for situations of poor execution of the surface layer, quantified in this research by the parameter in-field air voids. This loss of performance has a direct impact on highways operating costs. To analyse the loss of fatigue performance, eight field-applied asphalt mixes were evaluated, comparing laboratory compaction (5.50% air voids) with as-built in-field core samples (random variable air voids). The impact of increased air voids on LVE behaviour, fatigue life, and costs were investigated. Decrease in stiffness was observed for in-field air voids greater than 7.00%. Through the S-VECD model and FlexPAVETM software, a significant decrease in fatigue life was observed for in-field air voids greater than 8.00%. Costs, defined as costs per traffic request (N) (US$/N) were significantly affected for in-field air voids greater than this value (8.00%). Based on that, a Payment reduction factor (PRF) was proposed. In this way, it is concluded that the framework demonstrated throughout the paper, based on a mechanistic approach and using the FlexPAVETM, allows the evaluation of the construction quality impact on asphalt pavement cost. [ABSTRACT FROM AUTHOR]

More robust methods for predicting the performance of asphalt mixtures in the field have been established in recent years. However, the tests carried out to obtain the data generally make use of samples compacted in the laboratory with diameters that make it impossible to extract samples from field layers. This problem can be solved with the use of small samples with a diameter smaller than the compaction thicknesses used in the field. Although characterization tests of asphalt mixtures with small samples have already been performed in the literature, few studies have been carried out, thus denoting the need for more tests for a larger number of mixtures. This research aims to verify the behavior of smaller samples (38×110 mm) and to evaluate if they can provide the same linear viscoelastic (LVE) analyzed from the master curves and the rheological Model 2S2P1D (two springs, two parabolic elements, and one dashpot), the same fatigue characterization, and the same performance over time results for fatigue damage by pavement simulation in FlexPAVE software. The observation of LVE domain suggests a great consistency between the results obtained for the two test geometries. The same was observed for fatigue analysis based in the simplified viscoelastic continuum damage (S-VECD) model. The accumulated fatigue damage curves along the traffic and the cracked area (CA%) prediction obtained by FlexPAVE showed that the characterization by standard and small samples lead to concordant results. The small-scale specimen geometry tested in this research is an accurate and alternative method to full-size samples, with the ability to characterize the LVE behavior, the fatigue phenomenon, and performance simulations in the context of forensic analysis or other investigations that require the use of samples extracted from pavements in field. [ABSTRACT FROM AUTHOR]

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An alternative to obtain the structural response of the road pavement layers, to complement the information obtained through samples extracted on track, is the performance of deflection tests carried out with equipment such as the Benkelman Beam (BB) and the Falling Weight Deflectometer (FWD). Through a non-destructive structural evaluation, aiming to assess the behavior of the pavement structures of two monitored sections, located in Santa Maria/RS city. Thus, tests were performed with the FWD Equipment in each stake that makes up the extension of the two sections. Sequentially to the load pulses, deflections were also measured with the BB, aiming to find a local correlation between the results obtained from different equipment and in identical weather conditions. The deflection basins indicated higher deflection values, measured with the BB, in relation to those determined by the FWD. Regarding the maximum deflection, the results found by using the BB are, on average, 1.355 times higher than those obtained with the FWD. This correlation was obtained in the range of maximum deflection values measured between 25x10-2 mm and 99x10-2 mm, with asphalt concrete pavement surface temperatures between 19°C and 51°C. [ABSTRACT FROM AUTHOR]

Copyright of Anuario do Instituto de Geociencias is the property of Universidade Federal do Rio de Janeiro, Instituto de Geociencias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The resilient modulus backcalculation based on tests with the Falling Weight Deflectometer (FWD) is an alternative for the characterization of the material stiffness on the pavement layers. In view of this, by conducting semi-annual campaigns with the FWD, in two monitored sites in the city of Santa Maria/RS (Brazil), this paper aims to identify the differences between the results from the backcalculation procedures carried out with the programs BAKFAA, BackMeDiNa, Evercalc and MnLayer. In addition, the influence of bounding conditions between layers and the correction of deflectometric basins, as a function of temperature, on the results determined by the iterative process was evaluated. It was found that the attribution of total bounding in the interfaces considerably reduces the backcalculated modulus of the granular materials. Regarding temperature correction, the determination of the stiffness of the granular and subgrade materials was found to be adequate by performing a backcalculation without any adjustment in the field basins. In the case of the different programs, there was a certain uniformity between the results obtained, except for the cases of slightly higher modulus determined with BackMeDiNa for the asphalt coating, and the significantly lower stiffness obtained for the granular sub-base layer, with the Evercalc, when compared to other software. [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum: Technology is the property of Universidade Estadual de Maringa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As a proposed long-term pavement solution for bus stops and corridors in highly urbanized areas, four experimental continuously reinforced concrete pavement (CRCP) sections with different percentages of longitudinal steel were built in São Paulo, Brazil. The pavement sections are only 50 meters long each, a short construction length in comparison to traditional CRCP, which is normally built as long as the construction process allows. A four-year cracking survey of the experimental sections showed that the shorter section length, perhaps due in part to the lack of anchorage, results in a cracking pattern unlike that of the CRCP with traditional lengths. Additionally, two non-destructive tests were carried out to evaluate the structural performance of the experimental sections. First, deflection tests using a falling weight deflectometer (FWD) were conducted to measure the load transfer efficiency (LTE) across all cracks and to determinate slab parameters by backcalculation. Second, dynamic load tests to obtain the concrete stresses under a known load. The results show that the LTE values are adequate (above 90%) in all sections, despite its distinct crack pattern and that tensile stresses at the bottom of the slab are within critical strength values for the concrete. The results from this experimental study are discussed in light of the current literature for CRCP design and performance. [ABSTRACT FROM AUTHOR]