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 : 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.

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 : 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.