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Considering that the decision-making and planning of large-scale highway network under the condition of limited funds, there are some problems such as complex algorithm of feasible solution of maintenance scheme and low efficiency of optimisation process, a heuristic maintenance planning optimisation algorithm based on budget is introduced. This paper focuses on the performance prediction, the determination of treatment measures and the optimisation of the optimal scheme. Firstly, through the analysis of the technical process of prediction and treatment measures, the pavement performance degradation models of pavement condition index, riding quality index and rut depth index based on treatment level are established. Then, based on the characteristics of pavement performance degradation in China, the concept of maintenance benefit based on pavement performance index is proposed, and the cost-benefit optimisation model of highway asphalt pavement is established. A budget-based heuristic algorithm is proposed to solve the optimisation model for maintenance planning with budget constraints. Finally, taking Lian-Xu highway network in a case study, the optimal scheme of treatment measures and fund allocation for the maintenance section of the large-scale highway network is realised under the condition of limited funds, so as to verify the feasibility of the optimisation model. [ABSTRACT FROM AUTHOR]

Reflection cracks represent the predominant internal distress in semi-rigid base asphalt pavements and often accompanied by additional secondary issues that detrimentally affect the pavement structural bearing capacity. The propagation and deterioration of reflective cracks are affected by many factors, for example the interlayer bonding conditions. It is crucial to identify the propagation and deterioration of reflective cracks to prolong the life of pavement structure. The purpose of this article is to explore the influence of interlayer bonding conditions on the propagation laws of reflective cracks. This work employs the discrete element method(DEM) to explore the propagation patterns of reflection cracks accompanied different bonding conditions between the surface layer and base layer subjected to moving load. The results of discrete element simulation reveal a three-phase progression laws when the reflective cracks expand from the base layer to the pavement surface，involving rapid propagation, stable propagation, and failure process. With the interlayer bond strength decreases, expansion of reflective crack is significantly accelerated. Meanwhile, once the critical bond strength threshold is reached, complete debonding will occur between the surface and base layers. The results are ultimately verified through the core sampling from practical engineering using three-dimensional (3D) ground penetrating radar(GPR) detection, along with the radar image recognition of reflective cracks and poor interlayer bonding. The results will serve as a foundation for researching the mechanism and treatment measures for two internal pavement distress, namely reflection cracks and poor interlayer bonding. • 2D convex hull and external circle collision detection is applied in DEM modeling. • Propagation of reflective cracks accompanied poor interlayer bonding is simulated. • Reflective cracks propagation law in semi-rigid base asphalt pavement is clarified. • 3DGPR reliably detects reflective cracks and poor interlayer bonding. [ABSTRACT FROM AUTHOR]

Moisture damage seriously deteriorates asphalt pavement’s performance and durability and is therefore one of the major problems of asphalt pavements. Currently, researchers pay most attention to macro investigation of moisture damage in asphalt materials. However, moisture damage in asphalt materials can be attributed to the complex interactions between water, asphalt and aggregates occurring at the micro level so that macro tests cannot provide precise insight into this process and its mechanisms. To this end, two promising micromechanical tests, atomic force microscopy (AFM) and nanoindentation, were used in this paper to capture the micromechanical properties of asphalt binder and mixture samples before and after moisture damage. For data comparison, surface energy method and freeze-thaw splitting test were also used. Results show that AFM and nanoindentation are promising methods in investigation of asphalt materials’ moisture damage because they can quantitatively determine the loss of asphalt samples’ strength and also determine their damage types (adhesion or cohesion failure). Results of surface energy method and freeze-thaw splitting test correlate well with AFM and nanoindentation results in characterization of moisture susceptibility of asphalt binder and mixture samples respectively. It is concluded that these four testing methods can achieve a systematic and accurate evaluation of asphalt materials’ moisture resistance. [ABSTRACT FROM AUTHOR]

A two-stage viscoelastic-viscoplastic damage constitutive model and the corresponding parameters calibration method were briefly given. Then, the numerical algorithms of the proposed constitutive model were implemented based on a radial return mapping algorithm and realized using the user material subroutine in the well-known finite-element code. A rutting prediction method of asphalt pavement was proposed based on the two-stage viscoelastic-viscoplastic damage constitutive model along with a loading equivalence method. Laboratory wheel tracking tests under different temperatures, different loading levels, once variable amplitude loads, and step variable amplitude loads were conducted to evaluate the efficiency of rutting prediction. Finally, the test results were compared with finite-element simulated results. All the results indicate that the constitutive model and the corresponding rutting prediction method proposed in this paper can effectively represent the rutting developing rules under standard loading and complicated variable amplitude loading with reliable prediction accuracy. Meanwhile, the mechanism of rutting development can be characterized through analyzing the evolution rules of internal state variables based on the proposed constitutive model. [ABSTRACT FROM AUTHOR]

Rutting has an adverse effect on safety and riding comfort of pavement. Reliable prevention and prediction of rutting has been one of the major focuses in road research. This paper summarizes the methods available for rut depth prediction and performs a case study in two separate ways based on the data acquired from a full-scale indoor circular road test. One was to formulate the possible rut depth by integrating a four-element-five-parameter viscoelastic model and the layered strain approach. The other was based on an empirical method. It is verified that both methods are applicable in predicting rut depth within the near future after open to traffic. The empirical method, however, is also capable of predicting rut depth within the whole design life. And theoretical method proves inadequate because of the limitation of the model itself and also of the method for obtaining parameters. [ABSTRACT FROM AUTHOR]

In order to improve the durability of the asphalt pavement on a cement concrete bridge, this study investigated the effect of the modulus of the asphalt mixture at the bottom layer on the mechanical response of bridge pavement, along with a type of emerging bridge pavement structure. In addition, the design method and pavement performance of a high-modulus asphalt mixture were investigated using laboratory and field tests, and the life expectancy of the deck pavement structure was predicted based on the rutting deformation. The results showed that the application of a high-modulus asphalt mixture as the bottom asphalt layer decreased the stress level of the pavement structure. The new high-modulus asphalt mixture displayed excellent comprehensive performance, i.e., the dynamic stability reached 9632 times/mm and the fatigue life reached 1.65 million cycles. Based on the rutting depth prediction, using high-modulus mixtures for the bridge pavement prolonged the service life from the original 5 years to 10 years, which significantly enhanced the durability of the pavement structure. These research results could be of potential interest for practical applications in the construction industry. [ABSTRACT FROM AUTHOR]

Clay ball is a pavement surface defect which refers to a clump in which clay or dirt is mixed with hot asphalt mixture. Clay ball is typically caused by a combination of aggregate contamination of clay or soil, high aggregate moisture, and low production temperature at the asphalt plant. It usually appears a few weeks or months after paving under traffic load, after being liquefied and knocked from the pavement surface. Clay balls can be the source of potholing, raveling, and other issues such as moisture infiltration and reduced ride quality. This paper presents an investigation of the clay balls on US-31 one winter after construction in Hamilton County, Indiana. In order to understand the pavement condition, their severity was measured using both visual observation and infrared image collection system. In addition, a clay ball amount, its distribution pattern, and cores condition were evaluated. A precipitation effect on clay ball formation was investigated for finding a cause of the clay balls. The investigation found that infrared image collection system was appropriate in detecting the clay balls. The clay balls were elliptic in shape with 2.5 cm to 10 cm in diameter, and the maximum clay ball depth was almost penetrating the entire surface course. It was also found that the asphalt paving on the raining days or right after raining could increase the potential of clay balls. Monitoring of aggregate moisture during construction on or after raining days should be able to reduce the risk of clay balls. [ABSTRACT FROM AUTHOR]

Abstracts Use of bio-binder could address depletion of petroleum oil, pollution from residue waste, greenhouse gases emissions, and development of sustainable asphalt pavement that is both economically and environmentally friendly. This study investigated the physical and chemical properties of bio-oil rejuvenated asphalt with a series of test. A pre-treatment procedure was introduced to upgrade the biodiesel residue produced from waste cooking oil. Aged asphalt was prepared with a laboratory short-term aging method. The optimal content of the bio-oil was determined by conventional tests and related index, such as penetration, softening point, and ductility, to rejuvenate aged asphalt to its virgin level. Rheological properties, including viscosity, high-temperature rutting resistance, and low-temperature cracking resistance, of virgin, aged, and bio-oil rejuvenated asphalts were then investigated. Afterward, asphalt fraction components, functional groups, and microstructures of virgin, aged and bio-oil rejuvenated asphalts, together with the molecular information of bio-oil, were analyzed with the aid of micro testing techniques. Finally, the moisture susceptibilities were evaluated by conducting micro mechanical experiments. Results clearly demonstrate that bio-oil could soften aged asphalt and improve its low-temperature cracking resistance. Workability was improved due to the reduction of viscosity. Moreover, bio-oil was found to be a complex organic mixture with low molecular weight. Bio-oil was able to compensate aged asphalt for the loss of light components and may also interact with polymer in modified asphalt. Meanwhile, the aggregation of polar components after aging can be mitigated. Thus, the properties of aged asphalt would be enhanced with the addition of bio-oil rejuvenator. However, the anti-moisture performance of bio-oil rejuvenated base (Pen50) asphalt needs to be further improved due to the presence of hydrophilic functional groups and components. In sum, this paper presents the superiorities and potential application challenges of using biodiesel-residue-based bio-oil to rejuvenate aged asphalt. [ABSTRACT FROM AUTHOR]