Performance Modeling and Evaluation of Pavement Systems and Materials: Selected Papers from the 2009 GeoHunan International Conference

The conventional methods of pavement performance assessment indices were established by statistical analyses based on single item and multiple linear regression techniques. These regression models have many deficiencies and are not able to truly reflect the inherent complex nonlinear relationships among the performance indices. However, the Back-Propagation (BP) neural network method with ca comprehensive nonlinear dynamic system is able to address some of these weaknesses. In this paper, the International Roughness Index (IRI), Damage Rate (DR), Structure Strength Index (SSI), Sideway Force Coefficient (SFC), and Rutting Depth (RD) were selected as the five index variables. These variables are considered as some of the most significant factors that affect pavement performance. Additionally, these indices were easily classified as non-dimensional quantities and became input data units in the application of the BP neural network. In the study, Pavement Management Index (PMI) was accordingly sub-divided into five groups representing five grades; namely (1) excellent, (2) good, (3) medium, (4) subordinated, and (5) inferior. In this paper, pavement performance assessment based on the BP neural network method and PMI is presented along with a practical application example; followed by a summary of findings and recommendations

The performance evaluation of Portland cement concrete pavement (PCCP) is the key step in its maintenance, rehabilitation and overlay. A new evaluation index system was put forward considering the needs of PCCP overlay, based on the traditional evaluation index system, whose aim is mainly at maintenance. A systematic pavement performance evaluation model was established by using the fuzzy complex matter element method, and the weight of each factor was determined considering its objective and subjective weights, determined from Analytic Hierarchy Process (AHP) method and entropy method respectively. Finally, the pavement performance of a test road was evaluated using this method, and the evaluation result agrees with the actual pavement condition.

Pavement performance evaluation is one of the most important problems in pavement management system. In traditional methods for pavement performance evaluation, the weights of evaluation indexes are hard to determine and mainly depended on subjective judgment. The paper get the evaluation indexes by employing the concept of entropy and the weights of the evaluation indexes are obtained from surveying data. The matter element model for pavement evaluation is established. By calculating the dependence degree of the matter element model, the pavement evaluation is obtained. The results show that the matter element model has good ability to evaluate the pavement performance.

The dynamic loads imposed by moving vehicles have variations in load magnitude due to the surface roughness of the pavement system and larger dynamic loads than the design loads can affect the pavement performance and life. The purpose of this study was to find the relationships among the pavement surface roughness, variations in moving dynamic vehicle loads, and the performance of the concrete pavement system. The artificial pavement profiles of triangular amplitude variation were developed first to use in the analysis to find the effects of the wavelength and amplitude of the surface roughness on the moving dynamic vehicle loads. The analysis was performed and the relationships between the surface roughness elements and the load magnitude, the load frequency, and the phase between the front- and rear-axle loads, of the moving tandem-axle loads were found. To obtain the pavement responses to moving arbitrary vehicle loads, formulations were developed in the transformed field domain using a triple Fourier transform in time, space, and moving space. Based on the analysis results of this study, the correlations among the surface roughness, dynamic vehicle loads, and the pavement performance could be obtained.

Different pavement surface distress indexes have been developed in different regions in order to meet different engineering demands. Thus, a special pavement distress index can show the unique characteristics of a specific region. In this paper, we analyze and compare the weights of distress types for the PCI (Pavement Condition Index), the PCR (Pavement Condition Rating), and for the pavement condition index that was developed in Mainland China (PCI_MC). In order to estimate the weights of the PCI distress types, the integral method is used to calculate the area using a deduct value curve. Based on a normalization method, we set the M level of Alligator Cracking as a basic unit and show the distress type sequence for the PCI, PCR, and the PCI_MC. The descriptive statistics indicating the severity of the distress types for the three indexes are shown. Engineers who want to develop a new pavement distress index specific to the special demands of a particular region should consult the differences among these three indexes.

With the acceleration of urbanized advancement in China, governments' high investment and low efficiency in urban infrastructure projects have already become a worldwide problem. The BOT financing model can be combined with government policy supports, investor's abundant fund and advanced management. The BOT financing model in urban infrastructure projects has greater risks, so their risk management is of great significance. The paper establishes risk evaluation index system of urban infrastructure projects on the BOT financing model, and sets up the risk evaluation model by use of Analytic Hierarchy Process (AHP) and Fuzzy Mathematics. We partially modify weight of AHP, by Fuzzy Cluster Analysis. Next, we establish the risk allocation model of urban infrastructure projects. Finally, we carry empirical analysis about the risk problem of an urban infrastructure project. Through comparing with result of model evaluation and measure of the risk allocation, empirical analysis indicates that the evaluation result of the model can reflect the risk situation of project thoroughly and objectively.

Asphalt mixture is a viscous-elastic-plastic material, its performance changes with the conditions of the environment temperature and traffic loading. Although lots of measures have been taken from design to construction to control asphalt pavement early damages, such as selecting raw material and asphalt cementation material, mixture gradation, mixture mechanics capability, construction technology, and testing standards. But most freeways in China have still suffered early damages. In south regions, rut and water damages are the main problem because of the rainy climate and high environment temperature. According to the investigations of the existing traffic of Heng-Zao freeway in Hunan province and the axle-load condition, rut depth, on-site core samples, extracting test, thickness, field sampling and indoor rut test, the paper firstly analyzes the present condition, evaluates the pavement performance and construction technology, then analyzes the gradation type, finally summarizes all the possible causes of serious rut of the freeway. These can provide the references for the pavement design and construction in south regions.

By measuring the roughness of high-grade asphalt pavement, the time domain model of roughness based on international roughness index (IRI) was established by Inverse Discrete Fourier Transform(IDFT), which realizes the simulation of road roughness. The multiple-degree-of-freedom (MDOF) vehicle model was founded making use of the Dynamic Simulation software ADAMS. And with the time domain model, dynamic load spectrums for different grade pavements and different speeds were obtained by calculating dynamic load. Based on mathematical statistical analysis for load spectrums at different speeds and the influence of vehicle's actual loading condition and intermissive time, dynamic load models for different grade pavements were obtained. Combined finite element technology and the visco-elastic-plastic theory of asphalt mixture with the software ANSYS, the two-dimensional finite model of pavement structure was established. Considering the material characteristic of nonlinear, the method of calculating asphalt pavement rutting was put forward. The error is less than 10% between theoretical value and practical measurement rutting data of Handan-Changzhi highway. The result indicates that the method of rutting prediction, which based on the time domain model of roughness and the dynamic load coupled between pavement and vehicle is reasonable and reliable.

Most pavement construction in Korea today is conducted by following prescriptive specifications. The construction must be done according to the standard specifications and the contractor is responsible for any defects where the pavement quality does not meet the minimum requirements written in the specification. Adopting new materials and innovative construction technologies is limited under the current system. Many European countries have adopted the performance warranty systems to improve long-term pavement performance since the 1960's. In the performance warranty system, a specification defines a certain level of pavement performance as the minimum requirement. Examples of performance indices might include: rutting, roughness, cracking, skid resistance, etc. The prescriptive specification is no longer used in the performance warranty system. Instead, the contractor must satisfy the performance specifications of each index. One of the most important performance indices is the roughness of pavement. The method for evaluating the pavement roughness is essential in order to prevent conflict where there is a disagreement for evaluating results between the contractor and the client. The primary objective of this paper is to present a guideline for the calibration of the roughness measuring instrument of pavement by semi-manual and automatic methods in the performance warranty system.

Generally, the performance of asphalt pavement at high temperature is evaluated by rutting test. However, few researches focusing on the mechanical similarity between the rutting test specimen and the actual asphalt pavement structure has been carried out. As a result, based on Similarity Theory, the mechanical similarity between rutting test specimen and typical asphalt pavement structure through using three-dimensional finite element simulation was analyzed. At first, the similarity parameters were derived based on the Similarity Theory. Then, the loading types, boundary conditions and material parameters of finite element models were listed here. Finally, typical mechanical states in an actual pavement structure and rutting test were compared and analyzed. The result indicates that there are some differences in the distribution of stress and strain field between the two cases due to the different boundary conditions and object sizes studied. However, it can be made up with a proper design to the specimen and loading area in rutting test.

In this paper, three integral constant determination methods are proposed. First, the first point of modeling data sequence is used. Second, the last point of modeling data sequence is used. Third, the minimum point of fitting error in modeling data sequence is used. According to the above methods, six-step forecasts are respectively made by using six-group subgrade settlement observation data of Shaohuai expressway. The method of selecting integral constant is proposed by comparing and analyzing the predication results. Meanwhile, smoothing test for part of data is made in predication. For the two-group data which are not satisfy smoothness condition, cumulative settlement is used to build subgrade settlement grey prediction model, and the prediction effect was significantly improved.

In this study, a large amount of temperature measurements were obtained from a test site incorporating 3 typical pavement sections to establish a pavement temperature prediction model for freeways in Taiwan. Using thermocouples embedded at 20-mm distance in depth, temperature profiles of 3 different pavement structures were determined for 24-hr periods covering seasonal variations. Predictions made by BELLS model revealed that, at pavement temperature higher than 40°C, the model tends to underestimate pavement temperatures. Considering the climatic characteristics in Taiwan, the air temperature at testing time is used in the model. Also, a single sine function on a 24-hr clock system is used to simplify the predicting equation. The proposed pavement temperature model shows a good correlation between measured and predicted temperatures and has a coefficient of determination greater than 0.93. The pavement temperature prediction model is judged to be easier to use than the BELLS model, due to the fact that temperature data for the previous day are no longer needed, and will be used for temperature adjustment of future falling weight deflectometer data in Taiwan.

Reliable and realistic computer simulations of pavement behavior are important for improving the design process of pavement materials. Most simulations involve 3D modeling and therefore large finite element meshes. Hence, the systems that result from discretization involve many degrees of freedom and are difficult to solve. Constitutive modeling is an expensive process when mesh sizes increase. The introduction of a parallel direct solver reduces both computation time and the number of iterations to solve the system and yielding more realistic simulations.

The overweight vehicles create complex moving vehicle loads described as dynamic, three-dimension non-uniformly distributed contact stresses between tire and pavement surface. But existing calculation models and methods for structure mechanics of pavement cannot analyze the mechanical response of pavement under complex vehicle loads. Based on the theory of three-dimension elastic dynamics, the above problems were solved by using multidimensional Fourier Transformation technique after transforming moving coordinates, and general solution for multilayer elastic system under complex vehicular load was derived in this paper. Then, pivotal issues were analyzed for numerical methods implementation. Lastly, the calculation results were contrasted with results of spot test, which showed that the mechanical responses model and its numerical methods implementation are reasonable and correct.

Rules and parameters of mix design for pervious recycled concrete were proposed. Making use of proportioning mix method for stone matrix asphalt (SMA) and open graded friction course (OGFC), volume indexes including volume of voids(VV), volume of cement paste (VP) as well as percent air voids in coarse aggregate(VCA) can be seen as key parameters guiding for mix design. Mix design procedures for pervious recycled concrete were then put forward. Both compressive strength and water seepage velocity were put forward as verification indexes. A practical mix design example was given and the compressive strength and VV test result show that the new mixing design method for no-fines pervious recycled concrete or conventional pervious concrete is practical and feasible.

Various test procedures and index exist to identify the susceptibility of asphalt mixtures to moisture damage. This paper concerns on Marshall in Saturation State test that can be used to quantify the moisture damage of asphalt mixture. The procedure consists of Marshall test prior to different water bath for an extended period of time. The Retained Marshall Stability Ratio in Immersion Saturated State (RRISS) after the absorption test is used as an indication of sensitivity of the compacted mixture to moisture damage. The results show that RRISS is able to discern different asphalt mixture combinations in terms of their moisture susceptibility.

The three-stage creep behavior of asphalt mixture could be considered as the results of a competition between damage and hardening. Therefore, the damage and hardening variables were both introduced into Burgers model for modification. The series-wound dashpot in Burgers model was modified with a hardening variable and the undamaged mechanistic model was derived from rheological. Then, Kachanov's equation of damage evolution was adopted and a new creep constitutive model coupled with damage was established by Lemaitre's effective stress principle. Subsequently, static creep tests of two asphalt mixtures were conducted to validate the modified model, and an algorithm was established to determine the model parameters from typical laboratory data. The proposed model and algorithm were demonstrated through laboratory test results, and the analysis results matched the test perfectly. It is indicated that the proposed model can describe the three-stage behavior well.

For studying the accelerating role of dynamic pressure in moisture damage of asphalt pavement, based on fast Lagrangian finite difference method and Biot dynamic consolidation theory, fluid-solid coupling analysis was done considering asphalt mixtures as porous medium. Results revealed that development and dissipation of the dynamic pore pressure are coinstantaneous and this makes the positive and negative dynamic pore pressure and seepage force both alternate. The pumping phenomenon of saturated asphalt pavement under moving vehicle load was proved. The dynamic pore pressure increases with vehicle velocity. Effective stress and deflection of pavement all decrease due to the dynamic pore pressure. The maximum dynamic pore pressure occurs at the bottom of the surface course. So it's suggested that a drain course should be set up to change the drained condition from single-sided drain to both-sided drain, and thus the moisture damage can be limited effectively.

In order to study the influence of asphalt treated base (ATB) on pavement performance, a multi-layer elastic theory program is utilized to calculate the stress and strain in different pavement structures. Based on an instant heat conducting hypothesis, a finite element model is established to calculate the temperature stress and the strain of pavement structure when temperature reduces. Then the stress and strain of all the structural layers are calculated considering the corporate effect of loading and temperature. It is found that the stress caused by quickly-lowered temperate is far more lager than that caused by load. Thus it is revealed that the cracking in pavement is mainly caused by the temperature. Through contrast it is proved that the stress and strain caused by load and temperature of pavement with ATB30 are less than those of semi-rigid pavement. So ATB is proved to be an efficient way to decrease crack in asphalt pavement based on above calculation and theory analysis.

Permanent deformation (rutting) in the asphalt pavement is one of the main reasons cause the pavement damage. The focus of this paper is to study the factors affecting the permanent deformation by tri-axial creep test and the permanent deformation predicting of asphalt pavement. Four popular asphalt mixtures, AC13F, AC13C, AC16 and AC20 were chosen to do the repeated load tri-axial creep test under different voids, asphalt contents, different temperature and load levels. Based on the test result, it was concluded the Flow Number (Fn) of repeated load tri-axial creep test can distinguish the rutting resistance ability of different Hot Mixed Asphalt (HMA) mixtures. Temperature and Load levels have great influence on Fn of HMA as they do for asphalt pavement. The formula used for prediction of pavement permanent deformation was gotten based on the curve between the permanent deformation and loading number under different load and temperature levels. The formula was then calibrated by ALF test data.

Asphalt aging is an important factor to cause pavement cracking. Currently, researchers primarily conduct ageing tests on asphalt binder to study the ageing effect on asphalt pavements. However, the ageing effect is also dependent on the air void and aggregate properties. Therefore, this paper conducted ageing tests on asphalt mixtures to account for the influences of ageing effect on in-situ pavements. The LTAC properties of both plain asphalt mixtures and polymer-modified asphalt mixtures were investigated. Laboratory flexural and flexural creep tests were conducted on the beam specimens of asphalt mixtures, including those subjected to the short-term oven ageing and others subjected to the long-term oven ageing. Results indicate that polymer-modified asphalt mixtures have superior LTAC performance than that of plain asphalt mixtures. The long-term ageing has more significant effect on the LTAC properties than short-term ageing. The long-term oven ageing test is recommended to evaluate LTAC properties of the aged in-situ asphalt pavement. A performance index for the evaluation of the LTAC properties of the aged asphalt pavements was proposed.

The mechanical analysis is applied for the steel box girder bridge with orthotropic plate and pavement by means of Finite Element Method. The interaction between steel bridge and pavement is evaluated by the three stages in calculation. The analysis is focused on the mechanical features and the influential factors of the large components (cross diaphragm) and the local components (U-shaped ribs). Considering the mechanical effects by the heavy-duty vehicle load and heavy-load with braking, the interfacial shear failure is studied as one of the main reasons of damages. Moreover, in view of this major form of damage, this paper provides the corresponding mechanical analysis of the indicators.

Cohesive crack model (CCM) is essentially a type of non-linear fracture mechanics that can deal with large fracture process zones in inhomogeneous materials such as asphalt concrete (AC). CCM has been successfully used to model cracking under monotonic loading conditions. Its application to fatigue cracking is however limited due to the lack of well-developed mechanisms to account for progressive cracking damage caused cyclic loading. This paper incorporates the bounding surface concept into cohesive crack model and provides a systematic way for introducing hysteresis loop during loading and unloading into CCM. Model behaviors of the resulting cyclic CCM are then examined for reasonableness and flexibility.

Carbon fiber is used as the additive for the intelligent asphalt concrete. The relationship of the fiber volume and the concrete resistivity, and the relationship of the resistivity and the applied pressure were studied. The conductivity of asphalt concrete incorporating with carbon fiber changes with the magnitude of the applied pressure. This special characteristic of the material might be useful in the road engineering in two areas: (1) when pavement of this material are under loading, the change of the pressure can be reflected by measuring the resistivity of the material. The supervisor could monitor the loads of vehicle anywhere in the road network without the trouble of embedding sensors in the pavement. (2) If there are some defects that are difficult to be discover by visual method appear on the road, the supervisor could find them at the first time. According to the result of this paper, the conductivity of the asphalt concrete increases with the volume of fiber. The change is particularly prominent when the fiber volume is between the two mutant levels (with fibers of 4%–6%).