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The extraction and recovery of bitumens from bituminous mixtures is an important procedure in the paving industry. This work achieves to evaluate the rheological, permanent deformation and fatigue tests to calibration of the recovery procedure in the rotary evaporator. The protocol was divided in bitumens of known properties with laboratory aging and bitumens of unknown properties subjected to field aging. The materials were subjected to different distillation times and tested chemically, rheologically and for damage by fatigue and permanent deformation. The results indicated that the chemical FTIR test was not sensitive in capturing the presence of residual solvent in the bituminous materials due to low concentrations after recovery. The joint analysis of the |G*|, Jnr at 3.2 kPa of the MSCR and the Nf of the LAS test were consistent for determining the distillation times in the rotary evaporator to result in the absence of residual solvent and additional aging. [ABSTRACT FROM AUTHOR]

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]

The guarantee of traffic conditions with safety and comfort is one of the primary aims during a road structure design. Thus, this study aims to contribute to the roughness prediction, represented by the International Roughness Index (IRI), by developing models that describe the functional performance of Brazilian pavements. With monitoring actions carried out in sites located in Santa Maria/RS and Rio de Janeiro/RJ, the paper sought to evaluate the IRI's evolution. The mechanistic methodology was inserted to the study's scope by predicting the IRI evolution using the average fatigue damage, which was calculated with FlexPAVETM software. The procedure enabled the development of a mechanistic-empirical model, based on the initial IRI obtained after the end of the construction process and the computationally asphalt layers calculated damage. The developed model was also validated with other sites within the Brazilian territory, which results in significant practical applicability. [ABSTRACT FROM AUTHOR]

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The present paper presents the rutting evaluation of different asphalt mixtures in use in the state of Rio Grande do Sul, Brazil's southernmost-region, through the uniaxial repeated load test and the monitoring of mixtures performance in field, culminating in a criteria proposal for the parameter Flow Number depending on traffic. For this, five distinct asphalt binders were studied, five grain size distributions, three warm mixtures and 21 hot mixes, with different mineralogical types of aggregates, and 15 monitored test sites distributed geographically throughout the state. The results indicated that the binder modifications were the most influential characteristics in the asphalt mixtures rutting. Also, it was verified that the Flow Number criteria proposed so far in the country present significant differences. In this way, a new criterion was suggested, and it is possible to infer a good applicability for asphalt concretes, except for warm mixes and those with rubber binder. [ABSTRACT FROM AUTHOR]

Fatigue cracking is the main type of distress in flexible pavements in Brazil. Numerical models that are based on viscoelastic continuum damage (VECD) theory can help to explain the damage evolution process in asphalt mixtures, thereby allowing the proper analysis of the fatigue phenomenon. This paper aims to characterise and verify the fatigue behaviour of four test sites constructed with dense asphalt mixtures in Santa Maria, Brazil, employing field monitoring, linear viscoelastic characterisation, uniaxial cyclic fatigue testing, the simplified VECD (S-VECD) model, and FlexPAVETM software. This study's results are coupled with a cost/benefit analysis of the evaluated test sites. The constructed sites are compared to simulated optimal pavement designed using FlexPAVETM and fatigue damage transfer function. The results indicate that this study's methodology can predict fatigue damage evolution by identifying early cracking in two of the test sites and capturing good fatigue resistance in the other two sites. Furthermore, in both cases of early cracking, the design requirements for fatigue resistance could be met by increasing the asphalt layer thickness (optimal pavements), which significantly reduced the US$/NFATIGUE ratio. Thus, an improved cost/benefit ratio was realised for the pavements designed using this methodology and analysed using only an established fatigue criterion. [ABSTRACT FROM AUTHOR]