PURPOSES : Previously, the expansion state of the concrete pavement in which AAR occurred could not be determined. Because the current situation has not been evaluated, it has been difficult to prepare an appropriate response. In this study, a method for calculating the expansion amount of concrete pavement using the stiffness damage test (SDT) is proposed. METHODS : The SDT method was examined through a literature review. For the laboratory tests, specimens that generated AAR were produced based on the mix design (2018) of the Korea Expressway Corporation. SDT was used to calculate various mechanical properties, and their correlation with the expansion amount was reviewed. RESULTS : Using the SDT, various mechanical properties(elastic modulus, hysteresis area, plastic deformation, plastic deformation index, stiffness damage index, and nonlinear index) were calculated based on the expansion rate of the AAR. The elastic modulus was evaluated as the best predictor of the expansion rate. Thus, if the elastic modulus is calculated using SDT, a prediction equation can be used to calculate the amount of AAR expansion. This equation will need to be supplemented by further research. CONCLUSIONS : SDT was used to confirm that the expansion state due to the AAR of the concrete pavement could be indirectly evaluated. Among the mechanical properties related to SDT, the elastic modulus was found to be the most suitable for predicting the amount of expansion.

PURPOSES : In this study, a driving simulation testing equipment was developed to derive the optimal longitudinal tinting that can reduce the lateral vibration of the vehicle. Various types of longitudinal textures and tires were evaluated through simulation testing with the equipment. Based on the results, 3×3×16mm tinning as the optimal longitudinal texture was selected among 8 textures. METHODS : Based on the literature review, the causes of lateral vibration were analyzed, and parts and types for testing equipment development were reviewed. Driving simulation with testing equipment was conducted considering various textures and tires. To verify the test results, finite element analysis was performed under the similar conditions. And field test for two textures was conducted to find the optimal longitudinal texture. RESULTS : Based on the literature review, driving simulation test, finite element analysis and field test, longitudinal texture of 3×3×16mm is show the better performance compared to 7 textures. CONCLUSIONS : 3×3×16mm as longitudinal tinning for fresh concrete is show less lateral vibration than 3×3×12mm.

PURPOSES : The Korea Expressway Corporation has been working on an early remodeling project for the Jungbu Expressway, to prepare techniques for the rehabilitation of the old CRCP. In this study, a literature review, field survey, and thickness design using MEPGD were conducted. This is to provide a procedure for the pre-treatment, or repair of the existing pavement in the JungBu Expressway. METHODS : To evaluate the pavement condition of the JungBu Expressway, the existing PMS data were analyzed, and field surveys were conducted for each pavement condition. The SMA overlay thickness design was performed using the pavement thickness design program (MEPGD). In addition, the repair procedure was reviewed considering the characteristics of the old CRCP in Korea. RESULTS : From the analysis of existing PMS, field surveys, and laboratory tests, it was discovered that the old CRCP condition of the Jungbu Expressway was not satisfactory. Using MEPDG, the SMA thicknesses for each scenario were proposed as 5, 8, and 10 cm. In addition, appropriate repair procedures for each distress type(punchpout, multiple repair, re-failure, failure of longitudinal joint, etc.) of damaged CRCP in Korea were proposed. CONCLUSIONS : For the remodeling project of the Jungbu Expressway, appropriate repairs should be performed for each type of distress in the old CRCP. In this study, an appropriate overlay thickness and pre-treatment method are suggested.

PURPOSES : Korea Expressway Corporation has been working on an early remodeling project for the Jungbu Expressway to prepare methods for the rehabilitation of the old CRCP(Continuous Reinforced Concrete Pavement). In this study, the distress of the old CRCP was classified, and the engineering properties of the core specimens for each failure type were evaluated. Based on the test results, the concrete conditions of the existing CRCP were evaluated. This provides a basis for the pre-treatment or repair of the existing CRCP in the JungBu Expressway. METHODS : To evaluate the pavement condition of the Jungbu Expressway, existing PMS(Pavement Management System) data were analyzed, and field surveys were conducted for each pavement condition. The longitudinal rebar depth, rebar spacing, horizontal crack, and pavement thickness were examined through core sampling and non-destructive testing. In addition, the core specimens were used to evaluate the compressive strength, chloride penetration test, chloride ion penetration resistance, and freeze-thaw resistance. RESULTS : From the analysis of existing PMS data, field surveys, and laboratory tests, it was found that the old CRCP condition of the Jungbu Expressway was not good. Various types of failures occurred, and horizontal cracks at the rebar location, upward rebar locations, and rebar corrosion were confirmed. In addition, the compressive strength was considerably high, but the durability-related index was judged to be poor. CONCLUSIONS : For the remodeling project of the Jungbu Expressway, appropriate repairs should be carried out for each type of distress in the old CRCP.

PURPOSES : This study was conducted to evaluate the performance of pressure relief joints (PRJs) installed on highways for preventing blow-ups. METHODS : To evaluate the performance of a PRJ, pavement surface images were acquired by conducting a follow-up survey through on-site visual inspection and an automated pavement condition survey. The PRJ widths in the acquired pavement images were measured using image analysis software, and major distress in the PRJ was identified. The relationship between the performance period and the joint width was bi-linearized, and the causes of distress and repair methods for PRJ were suggested. RESULTS : As a result of the first survey, it became known that the width of a PRJ rapidly decreases after installation owing to an expansion of the concrete slab. The width of a PRJ continued to decrease, with 94% of the joint below 30 mm and 64% of the joint being below 10 mm, based on the fourth survey. The PRJ width of an Alkali-Aggregate Reaction (AAR) section decreased more than that of a normal section, but the difference in the average width between both sections decreased from 9.7 mm to 2.7 mm over the measured period. A bilinear estimation equation was developed based on the survey data. Through the estimation equation, it could be confirmed that joint contraction accelerated after installation owing to the effects of AAR, and that the joint widths of both sections converged to a similar level over the measurement period. As the result of the major distress analysis indicates, joint seal failure occurred in 70% of the joints, and the distress rates in terms of cracks, edge breakouts and spalling, and patching were 73%, 57%, and 28%, respectively. CONCLUSIONS : With the follow-up survey it could be confirmed that the concrete slab continued to expand despite seasonal changes, maintenance of the PRJ, and additional installation of new PRJs. The expansion of the concrete slab due to AAR is considered to be closely related to PRJ behavior. In addition, it is judged that major distress of the PRJ occurs at an early age owing to the instantaneous release of excessive compressive stress inherent in the slab during joint cutting.

PURPOSES : The objective of this study is to understand blow-up distress and causes in concrete pavement. METHODS : Feasible causes of blow-up and existing models were reviewed based on the literature. Three analytical models were adopted to perform a sensitivity analysis. Input parameters reflected the typical concrete pavement of national expressways. Evaluation of blow-up models was based on the amount of temperature increase and zero stress temperature of the concrete pavement. RESULTS : A review of the literature indicated that the five major causes of blow-up were: increase in temperature and solar radiation, alkaliaggregate reaction (AAR), friction characteristics between the concrete slab and subbase, joint closure (incompressible), and joint freezing. The sensitivity analysis revealed that the coefficient of thermal expansion had the greatest influence on the blow-up safety temperature. CONCLUSIONS : From existing blow-up model results, it could be concluded that the construction of concrete pavement during the winter season was not effective at preventing blow-up. In addition, an equivalent coefficient of thermal expansion that considers slab expansion due to AAR was proposed as a model input parameter for concrete pavement sections damaged by AAR.

PURPOSES : This study deals with a pressure relief joint, which is one of primary preventive methods of blow-up in concrete pavement. The purpose of the study is to estimate the joint sealant protrusion of pressure relief joint filler types according to horizontal displacement of concrete pavement by applying a variety of joint sealants and joint fillers. And test method for resistance of concrete to chloride ion penetration and test method for resistance of concrete to rapid freezing and thawing were conducted to analyze the improvement of concrete durability according to the primer types on concrete surface of stress relief joint. METHODS : Joint fillers of pressure relief joint were categorized into four different types, which are was styrofoam+backer+sealant(type 1), styrofoam+sealant(type 2), foaming styrofoam+sealant(type 3), and preformed joint+sealant(type 4). By varying the depth (10, 20, 30, 50 mm) from the top of the test specimens to the sealant’s surface, the test factors were evaluated for a total of 16 variables. When the specimen’s joint spacing decreased from 70mm to 10mm, the load was stopped. And the displacement of the center of the joint protrusion was measured. The test was terminated when the specimen joint spacing was reduced to 60 mm. The horizontal displacement at the time when the joint protrudes over the specimen surface is recorded and analyzed as the critical threshold displacement. RESULTS : According to the test results according to the type of joint filling material, it was found that there was a difference in the protrusion of the horizontal compression displacement according to the joint filling type. Under the current installation standard of 20mm, the preformed seal joint member showed the best crimping characteristics by securing the safety against protrusion until the horizontal displacement of 50mm occurred. CONCLUSIONS : The most common failures in pressure relief joints are those related to joint sealants, which can be minimized by changing the current joint type, installation depth, etc. to suppress them.