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Predicting faulting failure is useful in the optimal concrete pavement design. In this study, artificial neural networks and the random forest method have been used to predict the amount of this failure. The general prediction model was created by inserting 32 available input variables into artificial neural networks. An integer two objectives optimisation problem was designed to select features that significantly affect the faulting. After applying this method, 19 important variables were identified and used to develop two simplified models based on artificial neural networks and the random forest method. It is shown that the simplified model developed by artificial neural networks is the best model to accurately predict the faulting considering the number of input variables. The cumulative number of days when the precipitation is more than 12.7 mm, the elastic modulus of concrete slab, the number of days passed since the pavement was built, base thickness, the cumulative ESALs in the traffic lane, and the annual average number of days when the temperature is more than 32°C were identified as the most important parameters in predicting faulting using the random forest method. A Sensitivity analysis has been then performed on these variables and optimal values were determined. [ABSTRACT FROM AUTHOR]

Acid sludge is an environmental pollutant that is produced daily in large amounts in used engine oil refineries. Recycling this waste is the primary goal of this paper. This study used 'washing with water' and 'neutralization with quicklime' methods to prepare acid sludge for use in bituminous materials as huge potential disposal. The neutralised sludge by the 'washing with water' method was added to bitumen in the wet blending process at 10, 20, and 30 wt%. This product is brittle without proper adhesion and cohesion and cannot meet the standard limits as an acceptable binder. It performs like long-term aged bitumen, reducing penetration and ductility and increasing the aging potential and viscosity. In another method, the neutralised sludge by adding quicklime was added to the asphalt mixture to replace fine aggregates in 50, 75, and 100 wt%. Using this product decreases the aging potential and moisture susceptibility up to 36.4, and increases rutting resistance up to 34.7%, indirect tensile strength up to 17.3%, and resilient modulus up to 17.3%. Despite the presence of large amounts of heavy metals in acid sludge, using this product in asphalt mixtures is an economical and completely hygienic solution for disposing of acid sludge. [ABSTRACT FROM AUTHOR]

The effect of different volume filling ratios (VFR) of filler on the flexural creep stiffness and complex shear modulus of bituminous composites can be identified using BBR and DSR test setups. This research compares the findings of extensive experimental studies with the biphasic heterogeneous micromechanical finite element (FE) models to introduce the Effective Volume Filling Ratio (EVFR). The different VFRs from 10 to 40% were selected to fabricate asphalt mastic samples. The effects of loading regime, temperature, loading frequency, and VFR on the mechanical behavior of asphalt mastic were investigated, and practical formulations were proposed to determine the EVFR for both shear and bending stiffening. It was found that for VFR ≤ 20%, the differences between the FE and test results are negligible under both loading schemes. However, higher VFRs cause a further increase in the stiffening and percolation effects which produce more differences between the experimental and FE results. [ABSTRACT FROM AUTHOR]

Three-dimensional numerical finite element (FE) biphasic models verified against the experimental data were developed aiming to study the accuracy of FE modelling in the prediction of viscoelastic properties of crumb rubber-modified asphalt binders. In the numerical models, crumb rubber-modified asphalt binders are considered as a heterogeneous composite material consisting of the original asphalt binder and rubber particles which respectively have viscoelastic and hyperelastic behaviours. Three different dosages of crumb rubber including 10, 15 and 20 wt% of the original asphalt are added. To capture rubber particles distribution within the bituminous matrix, a random generation method by using the MOA software (French acronym for random object modeller) was implemented based on rubber's minimum and maximum particle sizes. In order to determine the viscoelastic properties of the original asphalt binder as well as the crumb rubber-modified ones, the dynamic shear rheometer (DSR) was used. The excellent agreement between the numerical FE modelling and experimental results witnessed the capability of biphasic finite element models to predict the visco-hyperelastic behaviour of crumb rubber-modified asphalt binders having an error lower than 9%. [ABSTRACT FROM AUTHOR]

This work focuses on the use of a heterogeneous generation method in order to develop a micromechanical model of Hot Mix Asphalt (HMA) that takes into account the effects of characteristics at the interfacial zone (IZ), where aggregate surfaces come into contact with the mortar matrix. Numerical calculations are conducted to investigate the effect of IZ mechanical characteristics on both the overall viscoelastic response of HMA and the local scale behavior. First of all, the HMA is treated as a biphasic material composed of mortar and granular inclusions. Next, a third phase is added between these two at each point of aggregate/mortar contact. Elastic and viscoelastic behaviors are assigned to the aggregates and mortar, respectively. The mechanical behavior of IZ varies between that of the inclusions and the matrix. At the global scale, these numerical results demonstrate that the use of triphasic micromechanical models improves the predictive accuracy of the dynamic modulus. At the local scale, a significant strain variation was found in each model. These results justify our triphasic modeling approach whenever local zone characteristics are the subject of interest. [ABSTRACT FROM AUTHOR]

In this research, the effect of adding SBS and vacuum bottoms residue on 60/70 neat asphalt binder have been carried out using classic and superpave testing methods. Adding SBS led to increase of softening point, elastic recovery and viscosity of asphalt binder. Besides, SBS reduced the penetration and ductility of specimens. Results of dynamic shear rheometer indicated that G and G sinδ reduced by adding the SBS content before and after aging while δ and G /sinδ parameters increased. Therefore, adding SBS improves the permanent deformation and fatigue resistance of neat asphalt binder. [ABSTRACT FROM AUTHOR]