PURPOSES : On a thin epoxy overlay pavement, epoxy is placed on the existing bridge deck pavement, followed by the spraying of aggregates on it. The bond strength between the existing pavement and overlay pavement is an important factor representing the performance of the thin epoxy overlay pavement, in addition to the skid resistance and roughness. Therefore, the bond strength, skid resistance, and roughness of a thin epoxy overlay pavement constructed for field tests under various field conditions are examined in this study. METHODS : The usability of epoxy and aggregates on a thin epoxy overlay pavement is identified by testing their material properties in a laboratory. A construction test is performed using the pretreatment conditions of the existing pavement surface and the number of layers of overlay pavement as variables. The bond strength, skid resistance, and roughness are analyzed 3 d after constructing the test pavement, and immediately before and after applying repetitive traffic loadings at 6 months. RESULTS : When the existing pavement is in good condition, as in this study, the bond strength of the thin epoxy overlay pavement is affected more significantly by the existing pavement condition than the material properties of epoxy, in which destruction is indicated in the existing pavement. The skid resistance is affected primarily by the condition of the aggregates sprayed on the epoxy. The pavement on which the aggregates are well sprayed indicate a high skid resistance. The roughness is not affected by any variables, such as the pretreatment conditions, number of thin pavement layers, and repetitive traffic loadings. CONCLUSIONS : A long-term evaluation of the bond strength, skid resistance, and roughness will be conducted on a test pavement. In addition, another construction test will be performed to investigate the performance of a thin epoxy pavement overlaid on a bridge deck pavement under inferior conditions.

PURPOSES : For high driving performance and service life of cement concrete pavement, construction quality must be secured. The construction quality is to be measured after pavement construction, but in this case, it is difficult to improve construction quality. Therefore, it is necessary to develop a method for measuring and correcting the profile of the pavement and subbase so that the construction quality can be monitored immediately after construction. METHODS : The device that can measure the construction quality of cement concrete pavement has been developed. Through the experiment simulating the field situation, the profile of the pavement and subbase was measured and calibration method was developed. RESULTS : In the measured profile, an outlier by the sensor and noise by the sensor and vibration were measured, and a step-like profile was measured differently from the acture one. To remove outliers, the boxplot outlier removal method was applied by overlapping each data group. The noise were removed by a low pass filtering. And, it was calibrated to a profile similar to the acture one through the sampling interval adjustment and the weighted moving average method. CONCLUSIONS : The method that can measure and calibrate the profile that is almost identical to the actual one has been developed. Accordingly, it is expected that the performance of the pavement can be improved by accurately monitoring the construction quality immediately after construction.

PURPOSES : Rut depth of asphalt pavements is a major factor that affects the maintenance of pavements as well as the safety of drivers. The purpose of this study was to analyze the factors influencing rut depth, using data collected periodically on national highways by the pavement management system and, consequently, predict annual rut depth change, to contribute to improved asphalt pavement management. METHODS : The factors expected to influence rut depth were determined by reviewing relevant literature, and collecting the related data. Further, the correlations between the annual rut depth change and the influencing factors were analyzed. Subsequently, the annual rut depth change model was developed by performing regression analysis using age, present rut depth, and annual average maximum temperature as independent variables. RESULTS : From the sensitivity analysis of the developed model, it was found that age affected the annual rut depth change the most. Additionally, the relationship between the dependent and independent variables was statistically significant. The model developed in this study could reasonably predict the change in the rut depth of the national highway asphalt pavements. CONCLUSIONS : In summary, it was verified that the model developed in this study could be used to predict the change in the National Highway Pavement Condition Index (NHPCI), which represents comprehensive conditions of national highway pavements. Development of other models that predict changes in surface distress as well as international roughness index is required to predict the change in NHPCI, as they are the independent variables of the NHPCI prediction model.

PURPOSES : Given that large-scale repair works of expressway bridge pavements have high maintenance cost and long traffic blocking time, the thin overlay method that maintains the existing pavement is attracting attention. In this study, because the bridge thin overlay has not been introduced in Korea yet, the basic physical properties of the epoxy thin overlay, which is mainly used for the bridge thin overlay, were investigated, and the skid resistance and bond performance were analyzed. METHODS : Basic physical property tests were performed on each of the epoxy binders, aggregates, and mixtures used in epoxy thin overlay. They were also compared and reviewed against foreign standards. The epoxy binders were tested for viscosity, gel time, and thermal compatibility. The aggregates were tested in terms of water absorption, specific gravity, and gradation. The compressive and flexural strengths of the mixtures were investigated. The epoxy thin overlay has the possibility of detachment of aggregates, so the skid resistance was tested according to the paving phase. In addition, to investigate the bond performance, which is the most important performance of the epoxy thin overlay, the bond strength test was performed by varying the moisture condition and treatment condition of the existing layer surface. RESULTS : The basic physical properties of the materials used in the epoxy thin overlays satisfied foreign standards except for the gradation of aggregates. The skid resistance did not satisfy the standard when the epoxy was exposed, whereas the skid resistance did satisfy the standard when the aggregates were exposed, even after the abrasion test. The bond strength of the epoxy thin overlay satisfied the standard in all cases. The bond strength was the highest when the relative humidity of the existing layer surface was 60%. CONCLUSIONS : The materials of epoxy thin overlay that could be obtained in Korea satisfied the basic physical property standards except for aggregate gradation. Given that the aggregate gradation could be adjusted, it can be concluded that the epoxy thin overlay could be introduced in Korea. In addition, it was confirmed that the skid resistance and bond strength of the epoxy thin overlay were high enough to be used in general road conditions. It was determined that the existing layer surface should maintain an optimal relative humidity of approximately 60% because the moisture condition affects the bond strength.