In this work, the effect that filler has on the aging of bitumen was analyzed but with the filler being incorporated by volume, not by weight. The Universal de Caracterización de Ligantes method was used as the process of accelerated aging, and a new direct tensile test was used to determine the toughness of the aged mixture and, thus, to assess the effect the filler has. All tests performed for this paper have shown the protective effect of the fillers used. The new direct tensile test developed by the Road Research Laboratory of the Technical University of Catalonia allows observation of how an increase in filler produces an increase in the breaking load and a decrease in the maximum deformation: the hydrated lime tends to stiffen the mixture less and make it less brittle than does calcium carbonate. To minimize the effect of aging on bitumen, the filler content proposed must be 20% or 30% less than the content recommended in conditions where there is no aging, so that when the mixture ages, the mastic is able to build up the maximum energy possible.The processes that a binder undergoes when aging, which cause its progressive hardening, may damage its aggregate-bitumen adhesive qualities and, thus, the cohesion of the mixture.The addition of filler to the mixture can improve adhesion and cohesion substantially (filler is a fine material-it passes a 0.063-mm sieve-derived from aggregate or other similar granular material). The bitumen-filler system (mastic), which is thicker and tougher than bitumen alone, improves the adhesive qualities and, in providing a covering film of greater thickness, also can slow down the aging processes. The effects of the addition of filler are directly related to their characteristics and the degree of concentration of the filler in the bitumen-filler system.The advantages that filler offers for the durability of the bituminous mixtures in the case of water action are due, in principle, to its physical characteristics, which reduce the porosity of the granular structure and thereby make access by water and air difficult. Moreover, the chemical nature of filler may mean greater affinity with the asphalt binder, which can improve resistance to the displacement that water causes the bitumen.Using immersion tests, Craus et al. assessed the influence that the type of filler had on the durability of the bituminous mixtures (1). They reviewed the usual criteria of mixture design, with analyses that simulated short periods of exposure to the environment (for example, for the case under study, the residual Marshall stability and the resistance of immersion-compression); they noted that mixtures that pass these tests usually fail completely in service. With the obtained results, they were able to modify the existing criteria for the classification of fillers, which had been based only on basic properties without consideration of the durability factor. From this work, the authors have continued studying the effect of the characteristics of fillers on the durability of the mixtures (2).Diverse...

In this work the effect filler has on the aging of bitumen is analyzed, but incorporating the filler in volume and not in weight. The UCL method is used as the process of accelerated aging and new direct tensile test is used to determine the toughness of the aged mixture and, thus, to assess the effect the filler has.All the tests performed for this paper have shown the protective effect of the fillers used. The new direct tensile test developed by the Road Research Laboratory of the Technical University of Catalonia, allows to observe how an increase of filler produces the increase of the breaking load and the decrease of the maximum deformation, observing that the hydrated lime tends to stiffen the mixture less and make it less brittle than calcium carbonate.In order to minimize the effect of aging on bitumen, the filler content proposed must be 20 or 30% less than the content recommended in conditions when there is no aging, so that when the mixture ages the mastic is able to build up the maximum energy possible.

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The excellent qualities of pervious wearing courses which enhance road safety and comfort are well known. However, there are very few test and control methods which allow these courses to be planned and used adequately. The design of the porous asphalts used in the construction of these pervious wearing courses depends on a number of rules of thumb derived from their use, but there is no test method or procedure which might allow their properties to be characterized and optimized. In this paper, we describe the procedure and planning criteria which are used in Spain in the design of porous mixes and which were established both from the behavior of these mixes in use and from the results of tests performed in the laboratory. The procedure used is based on optimizing two fundamental characteristics of these mixes: permeability and resistance to disintegration. We have developed two testing methods which allow both properties to be assessed. Permeability is assessed in situ by means of the Laboratorió de Caminos de Santander (LCS) permeameter and resistance to disintegration is evaluated by means of the Cantabrian abrasion loss test. These two tests optimize the design of these mixes and allow the effect on their behavior of using modified binders to be evaluated. We also describe the effects that these mixes have on adhesion, texture, and noise of the wearing course surface compared with other materials used in road surfacing.

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