Many research on mechanistic testing have come to likely conclusion that different test setup results in different performance. The aim of this paper is to analyse the stiffness modulus resulting from three different test setups, namely; Monotonic Uniaxial Tension Test (MUTT), Monotonic Uniaxial Compression Test (MUCT), and Indirect Tensile Test (ITT). They are monotonic tests. This paper will elaborate if there is any significant difference among the result of the first three tests. Master curves of stiffness modulus as a function of strain rate at reference temperature of 15 C were developed. The results show that there is no significance difference between the modulus resulting from the three tests performed at high strain rates. It's also shown that at low strain rate, the elastic modulus resulting from compression tests is in between indirect and uniaxial tension test's elastic modulus.

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Remarkable variances were observed in permanent deformation curves of a dense asphalt mixture captured in triaxial repeated load permanent deformation (TRLPD) tests. In order to explore the causes of such variances, each permanent deformation curve was characterized firstly by an indicator (B) of the permanent deformation rate at a steady state stage. Meanwhile, a linear relationship was found between the values of indicator B and the resilient moduli of specimens after 1000 load repetitions. Secondly, a profound discussion on the potential relationship between resilient moduli and air voids content was performed. The discussion showed that air voids content appears to have no contributions to the observed variances. Nevertheless, three failure modes, tension failure, shear failure and shear failure with barreling, were observed in the X-ray Computed Tomography (CT) images of failed specimens subjected to triaxial compressive stresses. Furthermore, a significant correlation between failure modes and the resilient moduli was found by means of one-way analysis of variance (ANOVA). Moreover, it was found that the internal weak zones observed in the CT images of intact specimens dominate the behavior of the permanent deformation of asphalt mixture and the internal structure is the essential cause of such variances in the case of this study. This exploration highlights the influence of the internal structure on the mechanical performance of asphalt materials and thus recommends that considerable attention should be paid on the internal structure other than the volumetric properties when selecting test specimens.

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Asphalt binder ages on time mainly due to oxidation during mixing, and in service along the years. The aging effect will diminish material viscoelastic properties until it becomes brittle. Once asphalt binder reaches its brittle stage, the material will reduce its capability to withstand repeated traffic loads while in service, (fatigue). There are four methods to enhance fatigue life of an asphalt pavement; among these methods is the use of antioxidants. The work presented in this paper summarises the research work where grape pomace residue has been used as an antioxidant. The research objectives were to evaluate and understand the antioxidant effect of this additive. Consistency and rheological tests where used to prove the relative effect for reducing aging when adding grape pomace residue. It was possible to demonstrate the antioxidant properties of the additive but at the same time, it was found that the small solid undissolved particles of the additive would produce a secondary effect that will it make more difficult to isolate the pure antioxidant effect.

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Noise produced from the tyre-road surface interface is one of the most important contributions to the overall traffic noise and there is an increasing requirement for predicting the tyre-road noise levels prior to road construction in the Netherlands. In practice, a model with a simple structure as well as a high accuracy is applicable in road engineering. Also, material properties are preferred to be used as input variables of the prediction model, which will facilitate the pavement design. Based on these considerations, models are developed for evaluating the tyre-road noise from the asphalt mixture compositions and road surface characteristics. They are statistical models developed from the measurements on thin layer surfacings in the Netherlands. Different regression methods, model types and input variable combinations are taken into account. The selection of the model is due to the fitness of the prediction and validation by using measurement data from in service road sections. Two models, which evaluate the tyre-road noise level from the surface characteristics and from material properties, respectively, are finally selected. By using these models, only a small number of input variables are required and reliable predictions can be provided. The models achieved in this study can be used for predicting the tyre-road noise generation in road engineering and investigating the influence of surface characteristics and material properties on tyre- road noise levels.

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Durable, therefore sustainable, road needs to attain specific characteristics, among others, resistance to permanent deformation and cracking. Determining the development of both characteristics are important to be able to predict pavement life and performance. In this research, permanent deformation occurring in three pavement sections was measured by a transverse profilograph. The pavement sections were simple two layer structures consisting of a gravel asphalt concrete (GAC) layer on a sand subgrade. The length and the width of the section are 16 m and 4 m respectively. These three sections were tested by means of Lintrack, an Accelerated Pavement Test (APT) which allows large number of realistic wheel load applied in a limited period of time. The results of this measurements shows the development of permanent deformation, which is defined as 'rut depth', as function of the number of load repetitions. Using relation exists between the radius of curvature of a deflection profile and the tensile strain at the bottom of a slab, the creep/permanent strain as a result of permanent deformation was calculated. This paper is carried out to determine relations between the rut depth and the radius of curvature and between the rut depth and the creep/permanent strain. Also, cracking development was observed upon these three pavement section. The result shows that there is a rather good correlation between rut depth and permanent/creep strain which is independent of the layer thickness.@en

A preventive maintenance strategy of spraying rejuvenators on asphalt pavement surfaces is being considered as a cost-effective and environmentally sustainable option to extend the service life of existing asphalt concrete pavements. Rejuvenators might penetrate into the asphalt concrete and soften (rejuvenate) the bituminous binder. In this paper, the rejuvenation effectiveness of two rejuvenators on an artificially aged mortar is assessed. Cylindrical mortar specimens were prepared from the artificially aged mortar and then treated by the rejuvenators. The rheological and shear fatigue properties of the reference and treated mortar specimens were measured using dynamic shear tests. Meantime, a three-dimensional column model was created to investigate the dynamic shear test's capability of detecting the rheological properties of a composite column with a soft material in its outer part and a stiff material in its inner part. From finite-element modeling, it is found that the shear modulus of the composite column is higher than that of the soft material and lower than that of the stiff material. However, the results of the dynamic shear tests show that the two rejuvenators did not decrease the complex shear modulus of the artificially aged mortar. In addition, the two rejuvenators did not change the shear fatigue life of the artificially aged mortar.

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Porous asphalt concrete is widely used as a surfacing layer on highways in the Netherlands because of its benefit that it is effective in reducing traffic noise. However, the service life of porous asphalt wearing courses is limited due to the fact that it is vulnerable to raveling. A preventive maintenance strategy using surface treatment material is being considered as a cost-effective and environmentally sustainable option to extend the service life of existing porous asphalt wearing courses. In this paper, the effect of a surface treatment to porous asphalt wearing courses is discussed. A surface treatment material was sprayed on the porous asphalt pavement surfaces in two field trials. Computed Tomography (CT) scans were performed on the porous asphalt concrete cores from the field trials to measure their volumetric properties. The rotating surface abrasion tests were used to determine the raveling resistance of the porous asphalt concrete samples. Finite element models with a realistic structure of the porous asphalt concrete were created for analyzing the stresses and strains as a result of traffic loads in the pavement surface with the surface treatment material. It is found that the effect of the surface treatment is positive.

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The mechanical impedance is a measure of the ability of a structure to resist motion when subjected to a given force. It has been considered related with tyre-road noise level of road surface. However, this parameter is seldom used to characterize mixtures in asphalt mixture design. In this study, the relationship between the mechanical impedance and the pavement stiffness is investigated based on laboratory and in-situ measurements. Mechanical impedance is tested by an impedance hammer device, while the stiffness is measured by the indirect tension test (ITT) method. Different types of road surfaces are taken into account, including thin layer noise reducing surfacing, dense surface and poro-elastic road surface. The influences of mixture compositions on mechanical impedance and stiffness are discussed. Statistical relationship between the stiffness and the mechanical impedance is developed based on the measurement results. Advices for noise reducing road surface design by considering mechanical impedance are given according to the research findings.

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