Sangyum Lee

Identification of Viscoelastic Functions for Hot-Mix Asphalt Mixtures Using a Modified Harmony Search Algorithm

This study proposes a modified harmony search (MHS) algorithm for determining the time-domain viscoelastic function of hot-mix asphalt (HMA) concrete materials. This MHS technique, employing a global optimization technique as well as a Wiechert model for the relaxation function, substantially enhances accuracy and consistency in the determination of viscoelastic functions of several HMA mixtures. In addition, this study shows how to determine a time-domain Prony series representation from the complex modulus in the frequency domain using the MHS algorithm. This can be efficiently used for numerical analysis with techniques such as the finite-element method. The results from lab frequency sweep tests of unmodified and lime-modified HMA at various asphalt contents were consistent with the functions obtained from the MHS algorithm.

Short communication: Improving a model for the dynamic modulus of asphalt using the modified harmony search algorithm

We report the improvement of a dynamic modulus model using a modified harmony search (MHS) algorithm to describe the resistance to rutting and fatigue cracking of asphalt concrete mixtures. The MHS algorithm was reformulated to improve the harmony search (HS) algorithm by introducing minimum and maximum bandwidths. Using the MHS algorithm, model parameters for lime-modified asphalt concrete mixtures were extracted and a good fit to the dynamic modulus data obtained from laboratory tests was achieved.

Study on the Functional Evaluation of Permeable Asphalt Concrete Pavement in Seoul City

The functional evaluation of constructed permeable pavements was conducted in terms of water permeable performance and noise reduction measurements in Seoul city. The field measurements of noise was based on two methods such as pass-by and novel close proximity(NCPX). The pass-by test and NCPX method are related to noise propagation and tire/pavement interaction noise measurement, respectively. For the water permeable tests, five sections were chosen; furthermore, the measurements were conducted for both of wheel path and non-wheel path area. For the pass-by measurement, three sections were chosen; furthermore, two different locations, which were near measurement point to traffic noise and far measurement point inside park or hosing complex, were selected for each section. Finally, tire/pavement interaction noise measurements were carried out at four locations. The results show that the functional performance of water permeability and noise reduction was well remained within 2 or 3 years after permeable pavement construction.

Study on the Noise Characteristics of Bridge Deck Pavements in Seoul Inner Ring Road

A measuring technique for tire-pavement interaction noise that uses a proposed noble close proximity(NCPX) method, which has been proofed in terms of the reliability and consistency of interaction noise measurement through several researches, equipped with surface microphones has been adopted in order to perform bridge deck pavement noise evaluations on four different pavement surfaces. Through field testing measurement of bridge deck pavement in Seoul inner ring road, the appropriate noise-measuring procedures have been used for evaluating the noise characteristics of four different surfaces. Measuring results show that tire-pavement noise levels vary depending on the surface types and vehicle speeds. Furthermore, the different characteristics of tire-pavement interaction noise can be found before and after the new surface construction of bridge deck pavements in terms of the 1/3 octave band analysis of vehicle speed.

Functional Drainage Evaluation of Block Paving through the Usage of Sludge and Wheel Tracking Test

As the percentage of permeable ground is reduced due to the increased impermeable roads of major cities, a heat island phenomenon can be dominantly observed, resulting in increased temperature. In addition, rainfall that would have been naturally absorbed and retained by the permeable ground is overflowed due to large volumes of run-off water, resulting in more sewer failures and increased erosion. In terms of permeable pavement system, block paving has been used anywhere as well as provides many years of service. The permeable block paving is an effective alternative to the more traditional asphalt or plain concrete for minor roads; furthermore, it looks a lot better than other pavements. In this study, the functional drainage evaluation of block paving was carried out, considering the usage of experimental sludge and wheel tracking test, in order to simulate the field condition of roads.

Comparison of Linear Visco-Elastic Complex Modulus and Yield Shear Stress in DSR Moisture Damage Test

Moisture damage tormenting asphalt pavement materials is a very complex interaction occurring between asphalt binder, its aggregate, and water. To estimate or index the moisture sensitivity of the asphalt pavement materials, compacted asphalt mixtures are commonly used in mechanical tests providing a strength-related parameter for evaluating moisture susceptibility. The compacted mixture structures, however, can cause a problem that fundamental properties between asphalt binder and its aggregate are easily stumbled behind the complicated aggregates-asphalt-air voids structure. In order to help resolve this problem and find the fundamental properties such as adhesion or cohesion strength, dynamic shear rheometer and rock disks were used in a modification way of the standard asphalt binder testing protocol, and functional parameters such as yield shear stress (YSS) and wet to dry (W/D) YSS ratio were found in the previous research. A protocol more advanced and in more detail than the previous research is suggested in this subsequent study. In addition, the relative independence of the YSS and W/D YSS ratio is proven upon heating effects, and the sensitivity of the parameters to material-specific is also reaffirmed, in more tests performed for this research. For this proving process, rheological values measured per heating cycle are compared and plotted. The results, analyzed with more data than measured in the previous research, indicate that YSS and W/D YSS ratio, even in the expanded data set, can be alternative parameters to evaluate moisture damage.

Analyzing the Fatigue Cracking and Maintenance of Asphalt Concrete Pavements, Based on Harmony Search Algorithm

PURPOSES : This research describes how to predict the life cycles of fatigue cracking based on NCHRP Report 704 as well as modified harmony search (MHS) algorithm. METHODS : The fatigue cracking regression model of NCHRP Report 704 was used in order to calculate the ESAL (Equivalent Single Axle Load) numbers up to pavement failure, based on using material parameters, composite modulus, and surface pavement thickness. Furthermore, the MHS algorithm was implemented to find appropriate material parameters and other structural conditions given the number of ESALs, which is related to pavement service life. RESULTS : The case studies show that the material and structural parameters can be obtained, resulting in satisfying the failure endurance of asphalt concrete structure, given the number of ESALs. For example, the required ESALs such as one or two millions are targeted to satisfy the service performance of asphalt concrete pavements in this study. CONCLUSIONS : According to the case studies, It can be concluded that the MHS algorithm provides a good tool of optimization problems in terms of minimizing the difference between the required service cycles, which is a given value, and the calculated service cycles, which is obtained from the fatigue cracking regression model.

Evaluation and Application of Active Noise Cancellation System for Reduction of Traffic Noise

The objective of this study is to evaluate ANC(Active Noise Cancellation) system composed of the prediction model for SPL(Sound Pressure Level) in accordance with the targeted frequencies. The ANC system and prediction model were developed in previous research. Its technical skills were based on ISO 9613. Moreover, we utilized the LimA Predictor to identify the accurate results of traffic noise obtained from measurement and prediction at the receiver points. To measure the traffic noise occurred at the road, the measurement method of Pass-by was conducted. This paper is focused on the reduction and superposition of sound longitudinal wave.: The theory of this paper is based on International Organization for Standardization 9613. In the frequency analysis, we conducted CPB(Constant Percentage Bandwidth) Analysis to determine the traffic noise properties related to the frequencies. In the previous research, FFT(Fast Fourier Transform) Analysis was used to eliminate the engine noise from the friction noise between the road and tire. The LimA Predictor was utilized to simulate the noise propagation and confirm the noise level. Also, the basic wave theory was applied to conduct the reduction of traffic noise from the prediction noise level. The study has shown that the reduction and superposition effect was almost from 11dB(A) to 22dB(A) when the superposition of waves is perfectly applied and the ANC system can be completely compatible with the practical traffic noise. The effect of sound wave reduction using ANC system at the relatively high frequencies was better than the low frequencies. Furthermore the errors of measurement and prediction were small at the range of high frequencies.

Laboratory and Field Performance Evaluation of Acryl Resin Based Solar Radiation Reflective Pavement

This study developed a solar radiation reflection pavement, so called a cool pavement, to lessen the urban heat island effect by coating a pavement surface with acrylic resins mixed with light-colored pigments. From a laboratory test, simulating solar heating process in pavements, the cool pavement reduced more than of pavement temperature at compared to a control porous pavement. With the increase of the mixing ratio of the pigments to acrylic resins, the temperature reduction effect increased, but its workability became worse due to higher viscosity. As a result, an appropriate mixing ratio was determined as 15%. The cool pavement had better durability than the control pavement: One quarter of Catabro loss and twofold dynamic stability. Its adhesion was also higher enough not to be debonded under traffic loading. In-situ noise and friction tests conducted in two field sites showed that the cool pavement reduced its noise level by 3.7dB in average and increased its friction level by 30% compared to the control pavement. The permeability of the cool pavement was little lower than the control pavement, but higher enough to satisfy the minimum requirement for porous pavements.

Study on the Performance Evaluation of Colored Asphalt Hot Mixtures through the Usage of Grain-typed Color Additive

Asphalt concrete pavement can be widely seen on urban streets, highways, parking lots, and bike trails. Asphalt concrete pavement is relatively temperature sensitive materials due to the viscoelastic behavior, which can be defined as flexible performance in summer and rigid performance in winter. In terms of maintenance, it can be fixed quite easily if damaged. In addition, asphalt concrete pavement is generally found to be black and grey in color. However, several colors can be adopted to change the appearance of plain old boring, black and grey. Generally, there are two types of color systems in hot mix asphalt concrete materials. One system uses colored cementitious material that is applied to pavement surface through coating the surface of the asphalt pavement. The major disadvantage to this system requires a careful skill set to be used on the construction site in order to prevent taking off the cementitious material. The other coloring system colors the asphalt hot mixtures through using color additives. The main advantage to this system is that the asphalt pavement layer is colored using the same techniques that are already used in paving. The disadvantage is that the colors are limited to mainly reds and browns. In this study, a suggested color additive was evaluated, based on rutting, moisture sensitivity, and fatigue cracking performance.