PURPOSES : The purpose of this study is to preliminarily examine the field applicability of modular pavement marking tape (PMT) to increase the lane awareness of motorists on existing roadways. METHODS : A pavement marking tape (PMT) comprises an adhesion layer and a paint coating layer. The adhesion layer is prepared using gussasphalt-based materials that have properties similar to those of existing asphalt materials. Thermal adhesion is performed to adhere the tape to the pavement. For the paint coating layer, polyurea materials are selected after reviewing the existing materials suitable for pavement lane marking. To conduct field evaluations on the adhesion layer, monitoring is performed after the pilot deployment of the PMT is completed. Twelve samples are prepared to investigate the optimal ratios for the mixture of paint coating layer materials. The durability of the PMT is examined using a turntable road-marking test system (RPA) with a wheel load on the samples. A total of 50,000 RPA, equivalent to P4, is performed. The performance is evaluated by capturing the retroreflectivity measure, which is used as an indicator of the pavement marking performance. The PMT is utilized on a roadway segment with significant heavy vehicle traffic, and continuous monitoring is performed to examine its performance in the field. RESULTS : Based on a visual inspection of the adhesion layer material, no significant issue is observed in terms of the adhesion performance of the PMT. Furthermore, the overall retroreflectivity obtained from the RPA exceeds 300 mcd/m2·lux. It is discovered that the optimal ratios for the mixture of polyurea and binder for the paint coating layer are 4:6 and 2:8, respectively, which results in a retroreflectivity that is 90% or above the initial retroreflectivity. Using a prototype of the PMT for field tests, a performance evaluation is conducted by analyzing the retroreflectivity measured after 2 and 7 weeks from the prototype deployment. The retroreflectivity measured for the first 2 weeks after the deployment appears acceptable for field use. However, the retroreflectivity is reduced significantly when it is measured 7 weeks after deployment, resulting in the necessity for a more reliable material that can retain long-term durability. CONCLUSIONS : The lane awareness of a motorist is crucial for accident mitigation under not only nighttime driving, but also severe weather conditions. In this regard, modular PMT is expected to increase the lane awareness of motorists, thereby improving the quality of lane marking materials. In this study, various exploratory field tests are conducted to analyze the field applicability of the PMT. It is noteworthy that the results presented herein are obtained from preliminary performance evaluations of the PMT. Hence, further investigations pertaining to the long-term durability of PMTs must be conducted using advanced test equipment such as an accelerated pavement tester.

PURPOSES : The actual service life of repair methods applied to cement concrete pavement is analyzed based on de-icing agent usage. METHODS : Highway PMS data pertaining to de-icing agent usage are classified into three grades: low (1~5 ton/lane/year), medium (5~8 ton/lane/year), and high (greater than 8 ton/lane/year). The repair methods considered include diamond grinding, patching, joint repair, partial depth repair, and asphalt overlay on five major highways. The service life of each repair method is analyzed based on the usage level of the de-icing agent. RESULTS : The service lives of the applied repair methods are much shorter than expected. It is confirmed that the service life afforded by diamond grinding, patching, and joint repair methods are not significantly affected by the use of de-icing agents, whereas that afforded by asphalt overlay and partial depth repair methods is affected significantly. The service life afforded by the asphalt overlay and partial depth repair methods decreases at high usage levels of the de-icing agent (greater than 8 ton/lane/year). CONCLUSIONS : Among the repair methods considered, the service life afforded by partial depth repair and asphalt overlay is affected significantly by the amount of de-icing agent used. Additionally, the differences between the expected and actual analyzed service lives should be considered in the next-generation maintenance strategy for cement concrete pavements.

PURPOSES : In this study, experimental findings regarding the frost resistance of concrete incorporated with mineral admixtures such as fly ash (FA) and ground granulated blast-furnace slag (SG) are presented. METHODS : To evaluate the performance of the abovementioned concretes under repeated freezing and thawing environments, based on the ASTM C 666 standard, the relative dynamic modulus of elasticity and mass ratio measurements are performed regularly. Furthermore, based on the ASTM C 672 standard, the concretes are exposed to 4% CaCl2 and NaCl salt solutions along with repeated 50 cycles of freezing and thawing. Subsequently, the scaling resistance is evaluated based on the scaled-off mass content and visual examination. RESULTS : SG is less effective in enhancing the scaling resistance of concrete compared with FA. However, the concrete incorporated with SG is more resistant to repeated freeze-thaw actions compared with OPC concrete. Meanwhile, compared with OPC concrete, the concrete incorporated with FA indicates a similar performance in terms of scaling resistance and better resistance against repeated freeze-thaw actions. CONCLUSIONS : The frost resistance of concrete depends significantly on the types of mineral admixtures used in concrete. This emphasizes the importance of selecting the appropriate binder to achieve durable concrete pavements in cold climate regions.

PURPOSES : Recently, interest in maintaining aged concrete pavements has been increasing. An asphalt overlay is generally used for pavement maintenance, and a tack coat is used to secure interlayer adhesion. Particularly, aged concrete pavements are required for higher adhesion performance of tack coats for attaching interlayers to materials with different properties. Insufficient interlayer adhesion could cause pavement damage, such as slippage, rutting, shoving, corrugation, and pothole. In this study, we examined the performance of interface adhesion by applying a tack coat material developed for maintaining aged concrete pavement. METHODS : In this study, we examined the effect of adhesion performance at the pavement interface, using a tack coat material developed for the maintenance of aged concrete pavement. RESULTS : The developed tack coat not only accomplished the performance objectives but also improved the results by more than 12 to 43%, compared to commonly used materials. CONCLUSIONS : The use of developed tack coat is expected to improve the interlayer adhesion and reduce the delay of the maintenance process in aged concrete pavement.

PURPOSES : This study aims at evaluating the use of an electromagnetic density gauge (EDG) to measure the in situ density and air-void content of asphalt concrete (AC) pavement. METHODS : In situ AC pavement density and air-void readings were obtained from two sites (Daegu and Ulsan) using an EDG. Calibration of the EDG was conducted by first obtaining density values at three different positions, on each pavement where core samples were extracted afterward. The core samples were then tested to obtain laboratory density and air-void values. The density measured using the EDG was then subtracted from the laboratory values to obtain the offset calibration values, which were then adopted to calibrate the in situ measurements using the EDG. Moreover, to analyze the effect of moisture on the pavement surface, EDG measurements were conducted under dry and wet conditions to compare the in-situ readings. RESULTS : The in-situ density readings of AC tend to be higher in moist/wet conditions. By applying the calibration value to the EDG readings, the density error percentage was reduced from 0.61% to 0.096%, and 0.64% to 0.16% for Daegu and Ulsan sites, respectively. Consequently, the air-void content error percentage was reduced from 12.8% to 1.04%, and from 10.07% to 1.78% for Daegu and Ulsan sites, respectively. CONCLUSIONS : The electromagnetic density gauge (EDG) is an effective tool for the non-destructive measurement of in situ pavement density. By applying offset calibration values, the error in the field readings was reduced, and the accuracy of the EDG measurements was improved.

PURPOSES : The purpose of this study was to develop the evaluation methodologies for spraying amount and sprayed condition of curing compound based on IoT technology when concrete pavements are constructed. METHODS : To measure the spraying amount of curing compound, a turbine type flowmeter was selected and a number of laboratory experiments were performed to verify the applicability of the selected sensor. To evaluate the uniformity of the sprayed curing compound on the concrete pavement surface, image process technologies were examined using pictures taken from the actual construction sites and from the test specimens. RESULTS : By performing experiments using water and curing compound, the selected flowmeter was verified to properly be applied to measure the spraying amount of curing compound with an acceptable accuracy. By conducting image processing using pictures of the sprayed curing compound on the concrete pavement surface, it was found that the 8 color analysis method was the best to evaluate the uniformity of the sprayed curing compound. CONCLUSIONS : From this study, it was concluded that the spraying amount of curing compound could be accurately measured using a turbine type flowmeter and the uniformity of the sprayed curing compound on the concrete pavement surface could be properly evaluated using an image processing technology.

PURPOSES : This study suggests an estimated texture depth (ETD) equation for concrete pavements, applicable to highway pavement texture, and the measurement method of mean profile depth (MPD) in a longitudinal texture. METHODS : First, we proposed the most suitable ETD equation through the correlation between ETD data and the measured mean texture depth (MTD) data. Second, we suggested a novel MPD measurement method, by checking the error of the ETD data and measured MTD data by the measurement method. RESULTS : The ETD equation presented by Fisco and Plati was considered the most appropriate for the transverse texture. In addition, the correlation between ETD and the measured MTD was good in the longitudinal measurement method. The ETD equation of Fisco and Plati is suitable for longitudinal texture, and the MPD measurement method obtained good results when applied to transverse measurements. To verify the novel measurement method, we confirmed the correlation between the SR and MPD data using a novel method. The correlation for the novel measurement method is 0.7. CONCLUSIONS : Accordingly, the ETD equation presented in the existing literature has a good correlation between ETD data and the measured MTD data, but it did not reflect longitudinal texture data. Therefore, we assumed the ETD equation produced in this study, and suggested the transverse measurement method in the longitudinal texture.

PURPOSES : The evaluation of the road pavement thickness in an apartment complex through a methodology for estimating the number of construction vehicles is presented. We also show the usability of the new design criteria. METHODS : A field survey plan was established by conducting literature and preliminary surveys, and the structural performance of each section of the road pavement was compared through a structural analysis program. The load on construction vehicles is required for analyzing the ESAL factors of construction vehicles; it is calculated as a methodology for estimating construction vehicles because it is difficult to measure the traffic volume through visual inspection. Accordingly, the extent of damage predicted by road pavement sections in apartment complexes was analyzed to examine the possibility of applying the methodology for estimating the number of construction vehicles. RESULTS : If the road crack exceeds 20% as a result of the site survey of a previous study, structural damage to the road pavement occurs from construction vehicles. Compared to the actual traffic volume observation, an error of 5% took place; therefore, it is necessary to perform a design such that the damage caused by the load of the construction vehicle be 15% or less for proper road performance. Structural analysis through the KENPAVE program showed that the damage caused by the load of the construction vehicle exceeded 20% in all sections except section B (with a thickness of 46 cm). CONCLUSIONS : Owing to the limitations of the test construction section and environmental conditions, it is necessary to assess the effects of various variables by conducting an analysis. This is expected to be applied as a design basis considering more reliable construction vehicles.

PURPOSES : This study uses deep learning image classification models and vehicle-mounted cameras to detect types of pavement distress — such as potholes, spalling, punch-outs, and patching damage — which require urgent maintenance. METHODS : For the automatic detection of pavement distress, the optimal mount location on a vehicle for a regular action camera was first determined. Using the orthogonal projection of obliquely captured surface images, morphological operations, and multi-blob image processing, candidate distressed pavement images were extracted from road surface images of a 16,036 km in-lane distance. Next, the distressed pavement images classified by experts were trained and tested for evaluation by three deep learning convolutional neural network (CNN) models: GoogLeNet, AlexNet, and VGGNet. The CNN models were image classification tools used to identify and extract the combined features of the target images via deep layers. Here, a data augmentation technique was applied to produce big distress data for training. Third, the dimensions of the detected distressed pavement patches were computed to estimate the quantity of repair materials needed. RESULTS : It was found that installing cameras 1.8 m above the ground on the exterior rear of the vehicle could provide clear pavement surface images with a resolution of 1 cm per pixel. The sensitivity analysis results of the trained GoogLeNet, AlexNet, and VGGNet models were 93 %, 86 %, and 72 %, respectively, compared to 62.7 % for the dimensional computation. Following readjustment of the image categories in the GoogLeNet model, distress detection sensitivity increased to 94.6 %. CONCLUSIONS : These findings support urgent maintenance by sending the detected distressed pavement images with the dimensions of the distressed patches and GPS coordinates to local maintenance offices in real-time.

PURPOSES : Pavement growth (PG) is a phenomenon whereby the overall length of a concrete pavement increases. The increase in length induces an axial compressive force in the concrete pavement slab, resulting in blow-up and damage of adjacent structures, such as a bridge. PG is influenced by several interacting factors, including climatic conditions, pavement materials, joint systems, incompressible particles (IP) infiltrating the joints or cracks in the slab, and an expansion caused by reactive aggregates in the concrete. However, it is difficult to predict PG and blow-up due to various complicated factors. Therefore, in this study, the pavement growth and blow-up analysis (PGBA) package program was developed to predict the PG and blow-up potential. The PGBA can consider the pavement configuration, expansion joint (EJ) configuration, climatic conditions, and design reliability. To evaluate the effects of influencing factors — such as climatic data, EJ configuration, pavement structures and materials, and design reliability — on PG and occurrence time of blow-up, a numerical example was demonstrated and a sensitivity analysis was performed. METHODS : To predict the PG, the concrete temperature was calculated using an appropriate analytical model. The trigger temperature for pavement growth(TTPG) was predicted using a statistical equation that considers pavement age, joint spacing, and precipitation. An analytical solution for estimating the concrete slab movement was performed. Through the calculated TTPG and the amount of PG, the service life of the EJ (width of EJ) can be predicted compared to the allowable width. In addition, by using analytical and finite elements, the safe temperature(Tsafe) for preventing blow-up occurrence was calculated. The blow-up occurrence was assumed to occur when the variation between the concrete temperature and TTPG was larger than Tsafe. RESULTS :As a result of the sensitivity analysis of maximum temperature and precipitation, the temperature and precipitation increase and the EJ service life and possibility of blow-up decrease. Sensitivity analysis was performed on the thermal expansion coefficient, pavement thickness, base layer type, concrete elastic modulus, and joint rotational stiffness in the concrete pavement structure and properties. In the PGBA program, the coefficient of thermal expansion and the type of base layer significantly affect the EJ life, as do the possibility of blowup and the elastic modulus. The joint rotational stiffness and pavement thickness had little effect on the EJ life but were found to affect the possible timing of blow-up. As a result of the PGBA sensitivity analysis of the width and spacing, which are the specifications of the EJ, the life of the EJ and the possibility of blow-up increased as the joint width increased; however, the EJ life and blow-up increased as the EJ interval reached a certain value. It was found that the possibility of a blow-up occurrence decreased. The results for the PGBA program in extreme weather conditions, the life span of EJs, and the possibility of blow-up in normal climates were reduced by over 50 %. CONCLUSIONS : As a result of PGBA sensitivity analysis, it was found that the substrate type, thermal expansion coefficient, precipitation, and alkali-silica reaction had the greatest influence on pavement expansion and blow-up.

PURPOSES : For large-scale construction, such as a concrete pavement, design and construction are not entirely consistent. If the inconsistency between design and construction is very large, construction quality is significantly degraded, affecting performance life span and driving comfort. The quality of pavement construction is managed according to standards. However, it is difficult to improve construction quality as the standard measures construction quality after construction is completed. Therefore, this study developed a system to measure the construction quality of concrete pavement in real-time and presented the corresponding standards. METHODS : A basic module for simultaneously measuring the width, thickness, and roughness of the concrete pavement was designed. Based on the measurement results of the distance measurement sensor, a calibration method is presented that can remove noise. The system process was developed to measure construction quality based on location and distance data, measured in real-time using GPSs and sensors. The field application experiment was conducted and the results were analyzed. RESULTS : The measurement module is properly designed to be used in concrete pavement construction sites. Noise was removed from the distance measurement sensor results according to the presented calibration method, leaving only the wave of pavement surface irregularities. As a result of applying the system process in the field application, a reasonable level of PRI was observed. CONCLUSIONS : In the past, the width, thickness, and roughness were measured after construction was completed and, if the standard was not met, construction quality control was performed via reconstruction or repair. Through this study, it is expected that the width, thickness, and roughness of the concrete pavement can be measured in real-time and, if the standard is not met, construction quality can be immediately controlled during construction to maintain high quality.

PURPOSES : This study aims to reduce the urban heat island phenomenon via utilization of porous asphalt pavements. METHODS : One of the many known functions of porous asphalt is that it reduces the urban heat island phenomenon. Indoor experiments were conducted to compare the surface temperature of sprinkled dense-graded and porous asphalt and outdoor experiments were conducted to verify the difference between the two asphalt pavements under external conditions. RESULTS : The results of the indoor experiment demonstrated that the temperatures of the two pavements were similar and that the porous asphalt pavement exhibited low temperature when sprinkled; the temperature of the porous asphalt was approximately 2 °C lower than that of the dense-graded asphalt pavement. The results of the outdoor experiment showed that the peak temperatures of the two pavements were approximately the same as usual. However, it was confirmed that the surface temperature of the porous asphalt pavement at night after sunset was lower than that of the dense-graded asphalt pavement and that the peak temperature dropped for approximately 1~2 days after the rainfall.. CONCLUSIONS : Porous asphalt pavement has a lower surface temperature than normal dense-graded asphalt pavement, under the presence of moisture in the pavement. In addition, it was confirmed that the lower surface temperature of the porous asphalt pavement is due to the low heat emission of the pavement at night. Accordingly, it is believed that the application of the porous asphalt pavement will not only have known effects but also significant impacts on the reduction of urban heat island phenomena.

PURPOSES : The purpose of this study is to verify the effectiveness of the developed ultra-thin-continuously reinforced concrete partition (UT-CRCP) overlay method through a comparative analysis of the early-behavior of the UT-CRCP with a 100 mm cutting overlay of the existing JPCP. METHODS : This study aims to minimize the vulnerability of the existing JPCP (joint section behavior) by overlaying the continuous reinforcement form to constrain joint behavior. For this purpose, the early-behavior of the JPCP section was measured and the early-behavior of the UT-CRCP section was compared with that of the cutting overlay of the same section. The testbed was constructed for comparative analysis of the two types of pavements and the early behavior was measured using the pure environmental loads, i.e., situations where there was no traffic load. For the UT-CRCP, which is a comparative test group, UT-CRCP was constructed approximately one year after the JPCP was constructed by milling the top of the existing JPCP by 100 mm. RESULTS : 1) UT-CRCP was shown to effectively reduce the amount of crack width change on the surface by 17 %, compared to JPCP, by placing reinforcement inside the pavement. 2) The restricting effect of the UT-CRCP was analyzed by comparing the strain generated by the cross-section depth for the two pavement types. As a result, the restricting rate by depth (20, 80, 120, and 280 mm) was 68.4 %, 80.2 %, 89.2 %, and 26.7 %, respectively. 3) We reviewed the comprehensive gauge restricting rate at depths of 80 mm and 120 mm (80.2 % and 89.2 %, respectively) and the absolute value of behavior that is located at the ±20 mm of the interface of JPCP and UT-CRCP. Thus, it was possible to estimate that both layers of pavements exhibit the same behavior (tied) at the interface between the two pavement layers. CONCLUSIONS : In this study, the early behavior of the BCO concept UT-CRCP overlay technique was analyzed and quantitatively presented to overcome the limitations of JPCP with relatively weak point behavior and to increase the commonality of aged concrete pavement to the performance of the new pavement.

PURPOSES : The purpose of this study is to measure and analyze the fugitive dust generated by each process through field tests to develop a technology to reduce fugitive dust generated during excavation-restoration work on road pavements. METHODS : The testbed was constructed based on a typical excavation-restoration construction section and comprised five sections for reproducibility and repeated measurements. The excavation-restoration work was divided into pavement cutting, pavement crushing, pavement removal, excavation, and restoration processes and fugitive dust generated by each process was measured. Fugitive dust (TSP, PM10, PM2.5, and PM1) was measured using a GRIMM particle spectrometer, which applies the principle of a light scattering spectrometer and can be measured in real-time. RESULTS : Analyses of the average mass concentration of PM10 generated by the excavation-restoration process are as follows: 1286.3 μg/m³ from pavement cutting, 246.8 μg/m³ from pavement crushing, 697.0 μg/m³ from pavement removal, 747.9 μg/m³ from excavation process, and 350.6 μg/m³ from the restoration process. In addition, the average particle size distribution of the excavationrestoration construction was in the order of PM10~PM2.5 (67 %), PM1 or less (24 %), and PM2.5~PM1 (9 %). The pavement cutting process is characterized by the emission of high concentrations of fugitive dust over a short time, compared to other processes. The pavement crushing process has the characteristic of steadily generating fugitive dust for a long period, although the emission concentration is small. CONCLUSIONS : In this study, it was found that the concentration and characteristics of fugitive dust generated during road pavement excavation-restoration works vary by process and the reduction technology for each process should be developed accordingly.

PURPOSES : The purpose of this study is to enhance the reliability of artificial intelligence for a noise-based pavement condition rating system (to a target performance of 95 %). METHODS : By comparing four types of pattern recognition artificial intelligence, this work acquires high-quality learning data and optimizes data learning through analysis of error characteristics. RESULTS : The system reliability improved up to 97 % (82 % in a prior study). In addition, 100 % was achieved for the E(F) condition grade, which has a direct impact on maintenance decision making. CONCLUSIONS : KNN-DTW (K-nearest neighbor dynamic time warping) is judged to be the most suitable type of artificial intelligence for a noise-based pavement condition rating system; a 4-grade system is the most suitable for classifying pavement condition.