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Rutting resistance is an important consideration for paving asphalt mixes. The cause of rutting is a shear strain in the asphalt pavement structure. Here, the rutting behavior of asphalt pavements was evaluated through laboratory simulations using the Hamburg Wheel-Tracking Test (HWTT), UK Wheel-Tracking Test (UKWTT), and Scaled Accelerated Load Simulator (SALS) test. The correlation between the three simulation tests was analyzed to determine the conversion factor (CF). Two parameters of temperature and speed of simulation testing were evaluated in this study. Subsequently, the representative frequency and dynamic modulus were calculated with consideration of viscoelasticity and time-temperature superposition. Using logical analysis, CF between the three simulation tests was validated. The results showed that the full-scale test yielded the highest stiffness modulus of 4,015 MPa, and the UKWTT yielded the lowest stiffness modulus of 1,857 MPa at 60 °C. From the HWTT results, it was found that the impact of moisture damage at 40 °C is not substantial compared to that at 50 °C. The conversion factor of HWTT at 40 °C, HWTT at 50 °C and UKWTT at 60 °C to SALS were 0.92, 0.74, and 0.63, respectively. Furthermore, the similar rutting performance among SALS, HWTT at 40 °C in dry and wet conditions, and HWTT at 50 °C in dry condition can be observed when the CF is applied. Lastly, the effectiveness of the conversion factor is diminished with increasing rutting damage. [ABSTRACT FROM AUTHOR]

In the past decade, numerous studies have shown that incorporating geogrid in the pavement could effectively improve the pavement performance. The major benefit of using geogrid in the flexible pavement is to improve its rutting performance as the result of the reinforcement function of geogrid. Mechanical-empirical pavement design guide (MEPDG) developed to provide the pavement performance prediction throughout its design life. However, MEPDG is not able to consider the effect of incorporating geogrid in the flexible pavement. In this study, a design procedure was proposed to obtain an equivalent geogrid pavement structure, which satisfies MEPDG design input requirements. In this procedure, a 2D finite element method was used to simulate geogrid reinforced and non-reinforced pavement structures. The iteration process based on stress-strain analysis of finite element model (FEM) used to obtain an equivalent structure input for MEPDG. The geogrid reinforced rutting performance can be predicted by analyzing the equivalent geogrid structure using MEPDG. A significant life improvement of pavement with geogrid was observed compared to pavement without geogrid. The results showed that the incorporating of geogrid in asphalt pavement layer significantly reduce the rutting of pavement layer, thus will contribute to extension of pavement service life. [ABSTRACT FROM AUTHOR]

Highlights • Work of adhesion of may drop up to 50% when aggregate moisture content of 10%. • Bond energy of WMA mixes diminish less with increasing aggregate moisture contents. • PM binder bond energy showed about 6.7 times greater than that of AC20 binders. • Quadrant plot can effectively rank the asphalt-aggregate adhesion properties. Abstract Warm-mix asphalt (WMA) is one technology that has been found to have potential in minimizing the environmental harm caused by road construction activities. Its low mixing and compacting temperatures have opened great opportunities for more sustainable development. However, because WMA is mixed at low temperatures, the drying process of the aggregate may fail to dry the WMA completely. The binder-aggregate adhesion property can be damaged by moisture remaining from incomplete drying. The present study investigated the effects of aggregate moisture on the binder-aggregate interfacial characteristics of WMA by evaluating its surface free energy and adhesive bond strength. The results showed that for the Pen 60-70 binder type, the aggregate AG in general showed the higher bond energy and aggregate SD showed the lowest bond energy among three aggregate types. Also, the bond energy diminishes with increasing aggregate moisture contents but the percent drops in bond energy is less when WMA additives was included. For the PM binder, SL aggregate group showed the highest bond energy and SD aggregate group showed the lowest bond energy. For the work of adhesion, the results showed that with aggregate with 10% moisture contents has destructive effects on the work of adhesion which may decrease to 50% compare to dry aggregate condition. Finally, the four quadrant diagrams can be used to combine two distinct property of the bond energy and the work of adhesion as the hybrid performance indicator to rank the effect of moist aggregate to the adhesion properties at binder-aggregate interface. [ABSTRACT FROM AUTHOR]