Thin asphalt concrete overlays are a maintenance technique that mainly restore the functional properties of pavements. One of the main issues in thin overlays is reflective cracking that can cause early deterioration and reduce their service life. For this reason, the purpose of this investigation is to evaluate the effect of material selection on cracking performance of asphalt concrete mixtures for thin overlays. In particular, this paper evaluates the role of aggregate skeleton gradation. The study of the effect of aggregate gradation was divided into two stages: (1) fine fraction content and (2) maximum nominal aggregate size. Based on this, up to seven asphalt mixture gradations were designed and evaluated through the Fénix test at different test temperatures. The results showed a significant correlation between the fine fraction content, and maximum nominal aggregate size, and the cracking performance of the asphalt concrete mixtures. Mixtures manufactured with a low content of fine aggregates, as well as small nominal maximum size, experienced a further improvement of their toughness. These results reflected the importance of considering not only the effect of asphalt binder and environmental conditions but also aggregate gradation in the design of asphalt concrete mixtures in order to achieve a desirable cracking performance.

The aim of this study is to analyze the effect of filler nature and content on the behaviour of bituminous mastics. Several mastics with different fillers and various types of bitumen at different concentrations were characterized by the dynamic shear rheometer (DSR). Cohesion and adhesiveness provided to a standard mixture by mastics obtained as described above were then assessed by the UCL method, which is based on the Cántabro test. Results show the great effect that both filler nature and filler content have on the mastic properties.

The aim of this paper is to study the influence of crumb rubber on the improvement of cohesion provided by bitumen. The UCL Method is a procedure for binder characterization based on the evaluation of the degree of cohesion provided by a set amount of binder to an aggregate of a set grading (standard mixture). This method can be used to evaluate both, the dry and the wet adding procedures. The results obtained show that the wet procedure presents clear advantages over the dry procedure with and without digestion, especially when the binders are manufactured by microscopic dispersion.

One of the basic assumptions of analytical dimensioning models of asphalt pavements is failure due to fatigue cracking of the bituminous layers. Furthermore, it is considered that the damaging effects of different traffic loads are linear and cumulative, per Miner’s law. However, the analysis carried out on the effect of temperature, rest periods, and ageing of the bituminous materials questions considering fatigue failure as the only and main assumption for the calculation of the pavement life. Ageing of the pavement asphalt layers results in stiffening and transverse cracking. Consequently, these asphalt layers are no longer of infinite extent in the horizontal direction and their response resembles that of a slab. The application of this last calculation assumption provides pavement sections more in line with those used in Spain in the Catalogue of Structural Sections, which is based on experience gained from the real behavior of those sections. The calculation based on the fatigue laws results in undersized structures. This paper shows the results of a strain sweep test implemented at the UPC Roads Laboratory, which was used to analyse all the aforementioned effects and to propose a calculation procedure for heavy traffic pavements considering transverse cracking of the asphalt layers.