PURPOSES : The exposed aggregate concrete pavement (EACP) is adopted to achieve low traffic noise and long-term skid resistance in European countries such as Belgium and Germany. In Korea, it is first introduced at the Myeon Cheon field site in 2010. It reduces 3 dB(A) from tire–pavement noise compared with transverse tining. Recent investigations show that EACP can reduce tire–pavement noise by an additional 5 dB(A) compared with transverse tining. In this study, the tire–pavement interaction noise of EACP is compared with that of conventional pavements such as asphalt pavement, next-generation concrete surfaces (NGCS), and transverse tining. METHODS : EACP is constructed at two field sites on the SOC research center and Yeo-Ju test road to compare the noise level via close proximity noise measurement. In addition, the noise is measured using two vehicle type based on vehicle speeds of 60, 80, and 100 km/h. RESULTS : The results of noise measurement obtained from the SOC research center are as follows: Porous asphalt pavement 92.8 dB(A), HMA 96. dB(A), transverse tining 100.1 dB(A), and 8 mm EACP 97 dB(A) at a driving speed of 80 km/h. For the case of the Yeo-Ju test road. The noise levels at a driving speed of 80 km/h are as follows: 6 mm EACP, 93.6 dB(A); asphalt grooving pavement, 94.72 dB(A); 8 mm EACP, 95.2 dB(A); NGCS, 95.2 dB(A); transverse tining, 104.1 dB(A). CONCLUSIONS : The result of noise measurement of two sites in the SOC research center and test road shows that the noise level of the 6 mm EAC is lower than that of concrete pavement, such as tining and NGCS, and similar to that of asphalt pavement. In addition, the noise level of the 8 mm EAC is similar to that of the NGCS pavement. The noise reduction effect of the EAC is greater when small-sized coarse aggregates with lower flat and elongation ratios are used.

PURPOSES : In this study, a method for evaluating concrete bridge deck deterioration using three-dimensional (3D) ground penetrating radar (GPR) survey data and its in situ application are discussed. METHODS : Field surveys are conducted on two bridges in Yongsan-gu (Bridge A) and Seodaemun-gu (Bridge B) in Seoul using 3D GPR. The obtained survey data are used to calculate the dielectric constant map of each bridge using the extended common midpoint method. In addition, random points on both bridges are selected for the chloride content test in accordance with the KS F 2713 standard. The results from the dielectric constant map and chloride content test are compared. RESULTS : For Bridge A, it is discovered that the percentage of sections with a dielectric constant of 5.0 or less is 1.57%, whereas that above 5.0 is 98.43%; this indicates that the percentage of deteriorated sections for Bridge A is low. Meanwhile, for Bridge B, the dielectric constants calculated for the entire bridge exceed 5.0, which suggests no deterioration for Bridge B. Moreover, all the points selected for the chloride content test have less than 0.15% chloride content and have dielectric constants ranging from 5.0 to 7.0, which are favorable condition for the bridge deck. CONCLUSIONS : The analysis results of the dielectric constants of the concrete bridge deck obtained from the 3D GPR system are consistent with the actual chloride content results. Furthermore, additional verification of this method through field surveys on bridge sections with severe deterioration is highly recommended for future improvements.

PURPOSES : The purpose of this study is to analyze the crack and vertical behaviors of a continuously reinforced concrete pavement (CRCP) under three different steel ratios (0.6%, 0.7%, and 0.8%) using field measurement data acquired from isolated concrete slabs with transverse cracks. METHODS : Using an LVDT and a crack gauge, CRCP behavior data are acquired by segmenting a concrete slab into multiple sections based on the similarity in the longitudinal steel ratio of each section. To examine the vertical behavior of CRCP based on longitudinal steel ratios, three field experiments are conducted in February, May, and September three years after project completion. The minimum and maximum ambient temperature data for each section are acquired during the experiments. Using the data acquired, the vertical and crack behaviors of CRCP with 0.6% of longitudinal steel ratios are analyzed. In addition, the effect of the steel ratio on the vertical behavior as well as seasonal vertical behaviors are examined. RESULTS : Analysis of the vertical behavior of concrete slabs with a 0.6% steel ratio shows that the minimum vertical displacement occurred at the center of the slab, whereas a significant vertical displacement is detected on the edges of the slab. Based on examining vertical displacements formed along the direction of transverse cracks, it is observed that the vertical behavior is prominent around the shoulders, whereas similar vertical behaviors are observed at the center and joints of the slab. Furthermore, it is discovered that the minimum crack occurred at the center of the transverse cracks, whereas the maximum crack occurred on the shoulders and joints. Furthermore, it appears that the daily displacements of the vertical behavior at the center of the slab constitute approximately one-half of the daily displacements on the joints. Based on the results of vertical behavior as a function of the longitudinal steel ratios, it is discovered that steel ratios of 0.7% and 0.8% yield the most prominent vertical behaviors around the edge of the shoulder in the winter, spring, and fall seasons. The seasonal deviations of the vertical behaviors based on the measuring positions of the longitudinal steel ratios appear less significant at the center of the slab than those on the shoulder. In particular, for the slab with a steel ratio of 0.8%, subtle vertical behaviors are observed at the center. It is discovered that the seasonal deviation of the vertical behavior measurements varying by the measuring locations of the steel ratios appears less significant at the center of the slab than at the shoulder, and that it decreases with the steel ratio. CONCLUSIONS : CRCP generates cracks on the slab; however, they are managed by rebars in the CRCP. This study reveals that the major vertical and crack behaviors of CRCP occur around the shoulders than at the center of the CRCP slab. Therefore, new methods for managing cracks on the CRCP shoulder should be developed to improve the performance of CRCP. It is hoped that the results presented herein will be useful for the advanced analysis of CRCP behaviors.

PURPOSES : The purpose of this study is to identify the dynamic behavior of a cement concrete paving machine (paver) by measuring its response using accelerometers. This is because the dynamic behavior of pavers affects the quality of data from various applications of IoT sensors, such as laser, ultrasonic, optical sensors and so on. Therefore, it is believed that the understanding of dynamic behaviors can contribute to the effective use of various IoT sensors for the acquisition of real-time quality control data in pavement construction. METHODS : Dynamic signals are obtained using accelerometer sensors to identify the dynamic characteristics of paving machines. The main parameters for acquiring dynamic signals are the status of the machine’s operating or standby conditions, and available locations for attaching various IoT sensors. Time domain data are logged at a particular sampling speed using a low-pass filter, subsequently, they are converted to digital data, which are analyzed on three rectangular axes. In addition frequency analysis is conducted on the measured data for identifying the peak frequencies, via FFT (Fast-Fourier-Transform) using MATLAB. RESULTS : The magnitude of the x-directional vibration is higher than that of any other direction under the paver’s operating or standby condition. However, signals from the smoother beam show that the z-directional vibration is more significant in the operating status. It means that the primary vibration depends on the location. Furthermore, the peak frequencies are quite various depending on the status of a paver and its sensing location. CONCLUSIONS : The magnitude of machine vibration and peak frequencies at each status or location are identified from time- and frequency-domain data. When using IoT sensors for quality control or monitoring pavements in construction, the dynamic characteristics of a paver should be considered to mitigate the interference of signals from the paver body or its elements.

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.