The suggested approach in this study provides the structural integrity determination procedures of layered asphalt material pavements, which evaluate the relationship between the destructive strength of dynamic cone penetration (DCP) and the nondestructive stiffness of falling weight deflectometer (FWD) based on field-testing, to check whether the national standards of quality assurance are appropriate. We begin with a brief introduction of some basic nonlinearity evaluations and relationships in FWD loads and deflections, as well as the interchangeable relationships between the DCP index and resilient modulus. To determine the appropriate relationship equations, we compare the discrepancies between the calculated deflections of the discrete spectral solution, based on the material stiffnesses obtained from destructive DCP tests and asphalt mixture evaluation, and the measured deflections obtained from FWD field tests. Finally, the deflection basins are appropriately compared; then, we determine whether the national integrity evaluation standard of layered material structure is quietly accurate, based on incorporating the relationship equations of destructive testing data and material stiffnesses into the discrete spectral solution of layered structure. In summary, this study estimated layer moduli using DCP-based empirical correlations, applied them in a DSP (discrete spectral program) forward model, and compared the predicted and measured FWD deflection basins. Layer stiffnesses were not derived from FWD data via backcalculation or other inverse methods; therefore, no direct comparison between DCP- and FWD-derived stiffness values was made, nor was a direct DCP–FWD relationship established.

Tack coat application rates and testing conditions differ among nations and construction conditions because various tack coat materials are available. In this study, newer materials are optimized for addition to porous asphalt pavements exposed to torrential rainfall, which is common in South Korea. Interface shear strength (ISS) tests are used to define the optimum application rates (OARs) of tack coat materials generally used in South Korea, by reference to the Korean Design Standard (KDS), the Korean Construction Standard (KCS), and features of pavement construction and bonding. We performed ISS tests using asphalt mixtures with porosities of 3, 5, and 7% to explore the effect of porosity on shear strength. The ISSs associated with varying tack coat proportions were earlier determined by creating polynomial regression equations. Here, we develop a predictive model using a non-linear function to estimate the OAR of tack coat and compare our approach with the earlier polynomial regression analysis. Based on the ISSs, the golden section search method was applied to define the OARs afforded by the predictive polynomial function. We used the generalized reduced gradient algorithm to construct a nonlinear predictive function using data from the ISS tests. Finally, our comparative analysis showed that the predictive model using the non-linear function was superior to the polynomial model in terms of both error rate and predictive tendency.

Here, we develop a model predicting the dynamic moduli of hot-mix asphalt/concrete using the extended Kalman filter (EKF) algorithm and draw frequency-domain master curves. Discrete dynamic moduli were obtained via impact resonance tests (IRTs) on linear viscoelastic (LVE) asphalt at 20, 30, 35, 40, and 50°C. Typically, viscoelastic characteristics have been used to derive asphalt dynamic moduli; compressive frequency sweep tests at different frequencies (Hz) and temperatures are employed to this end. We compared IRT-derived viscoelastic master curves obtained via compressive frequency sweep testing to those derived using the EKF algorithm, which employs a nonlinear sigmoidal curve and a Taylor series to explore the viscoelastic function. The model reduced errors at both low and high frequencies by correcting the coefficients of the master curve. Furthermore, the predictive model effectively estimated dynamic moduli at various frequencies, and also root-mean-square errors (RMSEs) which, together with the mean percentage errors (MPEs), were used to compare predictions.

An efficient computation method that allows for evaluating the capability of pavement structures subjected to realistic loading conditions on fatigue cracking is important for pavement engineers. This study developed a fast and reliable computation algorithm, based on evaluating the fatigue cracking resistance of flexible pavements using the principle of the multiaxial Viscoelastic Continuum Damage Mechanics (VECD). For this purpose, a viscoelastic analysis was derived for the viscoelastic multilayered pavement systems under a moving load and used for integrating the multiaxial VECD model into the developed solution. Because of the analytical nature of the algorithm, stiffness reduction by means of pseudo stiffness could be directly evaluated at any location and at any loading repetition over a three-dimensional pavement structure. The resulted evaluation indicated that overall fatigue cracking performance of pavement structures could be assessed by the bottom pseudo stiffness; however, the probability of top-down cracking was high in pavement structures with thick asphalt layers.

Broken-line markings on the freeway have been installed for delineation and lane division, which together are expected to potentially reduce the number of traffic crashes. Although these functions are clearly dependent on visibility, the practical application of broken lines differs greatly worldwide in terms of the ratio of the line segment to the gap length or the width of the markings. On Korean freeways, existing broken-line markings consist of 8-m line segments and a 12-m gap with a width of 15 cm, although the reasoning for these dimensions is not known. The present study began with the field installation of diverse broken-line marking alternatives under the regulated ratio of the line segment to the gap segment—that is, 1:2 in Korea. Using the installed markings, a visibility experiment with subjects riding in a vehicle moving at a speed of 100 km/h was performed. From this study, it can be concluded that the existing broken-line markings on Korean freeways are not ideal in terms of visibility and that broken-line markings with 6-m line segments and a 12-m gap with a width of 13 cm is preferred in terms of visibility. This alternative was recommended to later become the new nationwide standard for Korean freeways.

The objective of this paper is to determine a predictive model that uses the harmony search algorithm (HSA) based on available the multi-regression equation. The model employs the least squares method to predict the number of potholes in the Seoul metropolitan area. Independent variables were determined, based on traffic and weather data for each month in Seoul. Prior to the development of predictive models, empirical and stochastic factors that affect the occurrence of potholes were determined, resulting in a standardized regression coefficient from multi-linear regression analysis. A best-fit equation was derived from experiments using independent variables obtained from empirical and analytical approaches. The empirically and analytically filtered factors for each road management area in Seoul were used to develop the predictive models for the multiple regression analysis and the HSA. Fourteen predictive models were determined in this study. A performance comparison between these predictive models was conducted using the P-value, the root mean squared error, and the coefficient of determination.

PURPOSES : Nowadays, cavity phenomena occur increasingly in pavement layers of downtown areas. This leads to an increment in the number of potholes, sinkholes, and other failure on the road. A loss of earth and sand from the pavement plays a key role in the occurrence of cavities, and, hence, a structural-performance evaluation of the pavement is essential. METHODS: The structural performance was evaluated via finite-element analysis using KPRP and KICTPAVE. KPRP was developed in order to formulate a Korean pavement design guide, which is based on a mechanical-empirical pavement design guide (M-EPDG). RESULTS: Installation of the anti-freezing layer yielded a fatigue crack, permanent deformation, and international roughness index (IRI) of 13%, 0.7 cm, and 3.0 m/km, respectively, as determined from the performance analysis conducted via KPRP. These values satisfy the design standards (fatigue crack: 20%, permanent deformation: 1.3 cm, IRI: 3.5 m/km). The results of FEM, using KICTPAVE, are shown in Figures 8~12 and Tables 3~5. CONCLUSIONS: The results of the performance analysis (conducted via KPRP) satisfy the design standards, even if the thickness of the anti-freezing layer is not considered. The corresponding values (i.e., 13%, 0.7 cm, and 3.0 m/km) are obtained for all conditions under which this layer is applied. Furthermore, the stress and strain on the interlayer between the sub-grade and the anti-freezing layer decrease gradually with increasing thickness of the anti-freezing layer. In contrast, the strain on the interlayer between the sub-base and the anti-freezing layer increases gradually with this increase in thickness.

PURPOSES : The objective of this paper is to develop a pavement performance model based on the Bayesian algorithm, and compare the measured and predicted performance data. METHODS : In this paper, several pavement types such as SMA (stone mastic asphalt), PSMA (polymer-modified stone mastic asphalt), PMA (polymer-modified asphalt), SBS (styrene-butadiene-styrene) modified asphalt, and DGA (dense-graded asphalt) are modeled in terms of the performance evaluation of pavement structures, using the Bayesian algorithm. RESULTS : From case studies related to the performance model development, the statistical parameters of the mean value and standard deviation can be obtained through the Bayesian algorithm, using the initial performance data of two different pavement cases. Furthermore, an accurate performance model can be developed, based on the comparison between the measured and predicted performance data. CONCLUSIONS : Based on the results of the case studies, it is concluded that the determined coefficients of the nonlinear performance models can be used to accurately predict the long-term performance behaviors of DGA and modified asphalt concrete pavements. In addition, the developed models were evaluated through comparison studies between the initial measurement and prediction data, as well as between the final measurement and prediction data. In the model development, the initial measured data were used.

Due to the growing number of vehicles using the national road networks that link major urban centers, traffic noise is becoming a major issue in relation to the transportation system. Thus, it is important to determine noise model parameters to predict road traffic noise levels as part of an environmental assessment, according to traffic volume and pavement surface type. To determine the parameters of a noise prediction model, statistical pass-by and close proximity tests are required. This paper provides a parameter determination procedure for noise prediction models through an adaptive particle filter (PF) algorithm, based on using a weigh-in-motion system, which obtains vehicle velocities and types, as well as step-up microphones, which measure the combined noises emitted by various vehicle types. Finally, an evaluation of the adaptive noise parameter determination algorithm was carried out to assess the agreement between predictions and measurements.

A reliable method for determining the dynamic material characteristics of hot-mix asphalt using a Bayesian method based on Latin hypercube sampling, impact resonance testing (IRT), and the shift factor of linear viscoelastic (LVE) asphalt concrete specimens is reported. Discrete resonance moduli data were obtained from the IRT at temperatures of 5, 25, 40, and 50 degrees C. The shift factor of the LVE was used to translate the discrete points of resonance moduli to higher or lower frequencies, depending on the temperature of the specimen. Based on the temperature-frequency combinations, Bayesian statistical predictions were used to create a dynamic modulus master-curve representation, using the resonance moduli data and Latin hypercube sampling. The results for three different hot-mix asphalt mixtures were in good agreement with dynamic moduli data obtained using other testing methods. (C) 2014 American Society of Civil Engineers.

PURPOSES: It is theoretically well known all over the world, that porous hot mixed asphalt (HMA) with hydrated Lime improves moisture and rutting resistance, and reduces pothole occurrence frequency, as well as the life cycle cost (LCC). METHODS : Addictive in the two different formations of the liquid anti-stripping Agent and powder Hydrated-Lime was applied in this investigation in order to obtain relatively clear results according to their types and conditions. Firstly, the moisture conditions were set, and applied to the porous HMA mixtures with hydrated lime (anti-stripping agent). Next, it was followed by a non-destructive test with the application of three freeze-thaw cycles, which were individually carried out thrice to compare the results of the dynamic moduli. Lastly, the hydrated lime effect related to moisture sensibility to porous HMA has been verified through the analysis of the modulus results regarding the change rate of dynamic modulus per n-cycle. RESULTS: It is clear from this investigation, that the dynamic modulus is inversely proportional to the change in temperature, as the graph representing the rigidity of the thermorheologically simple (TRS) material showed gradual decline of the dynamic modulus with the increase in temperature. CONCLUSIONS: The porous HMA mixture with the anti-stripping agent (hydrated Lime) has been found to be more moisture resistant to freezing and thawing than the normal porous HMA mixture. It is clear that the hydrated lime helps the HMA mixture to improve its fatigue resistance.

PURPOSES : The hydrated lime-modified asphalt, which improves moisture resistance, is normally used for pavements to reduce the number of potholes. However, the method of applying the material properties of the lime-modified asphalt mixture for use in pavements is not covered in the Korean Pavement Research Program (KPRP). The objective of this research is to find a method for the design application of lime-modified asphalt`s material properties to the KPRP. METHODS: The section for test design is selected in some conditions which are related to the level of design regarding Annual Average Daily Traffic (AADT). To define the application methods of hydrated lime in the KPRP, the models of fatigue, rut and international roughness index (IRI) are determined based on the M-EPDG test results from some earlier research results. Moreover, it is well known that dynamic moduli of the unmodified mixture are not different from those of the lime-modified mixture. RESULTS: The performance results of hydrated lime-modified asphalt pavement were not very much different from those of the unmodified pavement, which meant the limited design regulations regarding fatigue failure, rutting deformation and IRI. CONCLUSIONS: The KPRP uses the weather model from the data for previous 10 years. It implies that the KPRP cannot predict abnormal climate changes accurately. Hence, the predictive weather data regarding the abnormal climate changes are unreliable. Secondly, the KPRP cannot apply the moisture resistance of asphalt mixtures. Therefore, a second level of design study will have to be performed to reflect the influence of moisture. It means that the influence on pavement performance can be changed by the application of hydrated lime in asphalt mixture design.

PURPOSES : A tack coat has been utilized to increase the bond performance between the surface layer and base course (intermediate course) at various road pavement sites. This is similarly true in other nations. Based on this connection, the objective of the present study is to evaluate the properties of hot mix asphalt (HMA) mixtures with an RSC-4 or BD-Coat and determine the application rate of the tack coat. METHODS : The HMA specimens were manufactured using superpave gyratory compaction. The HMA mixtures were composed of a 5-cm thick surface layer and a 10-cm thick base course. An impact hammer resonance test (IHRT) and a static load shear test were conducted to evaluate the performance of the HMA mixtures with a tack coat. From these tests, the dynamic moduli related to the high-frequency resistance and interlayer shear strength (ISS) of HMA could be obtained. RESULTS : The results of the dynamic moduli of HMA are discussed based on the resonance frequency (RF). To check the accuracy of the IHRT, we conducted a coherence analysis. A direct shear test using the application of a static load test was carried out to evaluate the interlayer shear strength (ISS) of HMA. CONCLUSIONS : The maximum ISS was demonstrated at an RSC-4 application rate of 462 gsm, and the maximum dynamic modulus was demonstrated at an RSC-4 application rate of 306 gsm. By averaging the results of the ISS, the maximum ISS values were obtained when a BD-Coat application rate of 602 gsm was applied.