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Asphalt pavement failure is directly related to the traffic and climate effects. Temperature and moisture severely impact pavement service life. It is known that moisture changes the stiffness and stress–strain distribution and all the mechanical behaviors of the mixture/structure. There is a huge interest in studying the impact of water on the behavior of flexible pavements, mainly on freeze–thaw regions under tropical climates with high rainfall levels. The scope of the present paper was to check the susceptibility to moisture-induced damage of dense asphalt mixes produced and applied on highways in Brazil's southernmost region using different laboratory tests: visual adhesion of coarse aggregate; tensile strength ratio (TSR), and dynamic modulus ratio (DMR). Thus, this study evaluated the morphological, chemical, and mineralogical properties of aggregates from 11 quarries, as well as the interaction between aggregates and the respective bituminous binders. Rocks with high Si contents performed worse in visual adhesiveness tests; chemical ratios such as Fe/Si above 1 and Ca/K above 5, as well as the rougher texture of aggregates, considerably improved the coating, reducing the failures in adhesion. Results of TSR and DMR, after applying the induced moisture damage cycle, indicated greater susceptibility to conventional binders than mixtures containing modified binders in their composition. The action of moisture damage for most mixtures caused a reduction in strength and stiffness, warning of a decrease in the binder's ability within the mixture, completely changing the distribution of efforts within the structure. Therefore, from this study, it is possible to suggest using DMR instead of TSR to assess susceptibility to moisture damage. [ABSTRACT FROM AUTHOR]

Pavements need to have adequate structural, geometric and signaling conditions, in order to prevent accidents and to ensure safer transportation. In Brazil, asphalt pavement projects require proper volumetric and structural parameters, where as functional aspects, such as tire–pavement friction, are not always considered in the asphalt mixtures design. One of the most important factors in the tire–pavement friction is the asphalt mixes texture. In this context, the main objective of the present study is to evaluate a method for characterization of asphalt mixtures texture properties using digital image processing (DIP) techniques, demonstrating how these results can be correlated to the results of conventional tests and to the aggregate particles’ shape properties, such as angularity and surface texture. For this purpose, three hot mix asphalt (HMA) with different aggregate gradations and composed by aggregates with different shape properties were analyzed. Two HMA used in road pavements were produced, one with aggregate particles in their original form, and the other one with polished aggregate particles. The third mix was a HMA used in airport pavements, produced with non-polished aggregate particles. Besides these three mixes evaluated in the laboratory, four HMA used in the field were analyzed in order to compare the results obtained from the DIP, and the ones obtained using conventional texture and skid resistance tests. The results showed that the correlations between the HMA texture properties obtained using DIP and those obtained through conventional tests are not as good as expected. Moreover, the results indicated that the HMA particle size distribution directly affects its texture characteristics. Regarding the aggregate particles shape properties, it was found that small variations in these properties do not provide major variations in the results of HMA texture obtained by the DIP technique. [ABSTRACT FROM AUTHOR]

• The study evaluates the use of lateritic aggregates as an alternative to granitic aggregates. In addition to the study of this type of material, an analysis is carried out regarding the influence of particle size analysis methods on asphalt mixtures with these aggregates: • The research points out that the DAR technique was not efficient in estimating the permanent deformation and that the particle size selection methods did not interfere with the rigidity of the mixtures. • Mixtures with lateritic aggregates showed good performance regarding permanent deformation and resilience. However, greater susceptibility to the action of water, which limits the use of this material in regions with high rainfall. • Asphalt mixtures produced with lateritic aggregates are mainly indicated in countries with a tropical climate and low rainfall, such as the Northeast region of Brazil, where there is a significant presence of this material. The aggregates of asphalt mixtures provide resistance to most of the load applied to the pavement, so it is important to evaluate the physical and mechanical properties of the aggregates. In some regions of Brazil, the availability of traditional aggregates (granitic) is becoming scarce due to the rapid increase in infrastructure projects and the longer distance of deposit to the paving works. To address the above issues, we tried to find substitutes for granitic aggregates in asphalt mixtures. Laterite is a tropical or sub-tropical weathering product, abundant material in the North and Northeast of Brazil. The study aimed to evaluate the performance of asphalt mixtures produced with lateritic and granitic aggregates and verify the influence of National Department of Transport Infrastructure (DNIT), Bailey, and French particle size selection methods in the mixtures, through mechanical tests. The Dominant Aggregates Range (DAR) technique was used to evaluate the behavior of the mixtures in terms of permanent deformation. The asphalt mixtures were analyzed through dynamic modulus, flow number, fatigue test, resilience modulus, and Modified Lottman test. The analysis of the mixtures by the DAR method showed results that did not corroborate the results of the mechanical tests. However, all the analyzed mixtures showed good performance regarding permanent deformation, especially the mixtures with lateritic aggregates. The asphalt mixtures produced with lateritic aggregates present better mechanical performance, enabling their use mainly in countries with a tropical climate and low rainfall, such as the northeast region of Brazil. The French method showed equivalent mechanical performance and even superior to the DNIT method, commonly used in Brazil. [ABSTRACT FROM AUTHOR]