PURPOSES : The purpose of this study is to investigate the tendency of material property estimation under different concrete distress conditions and curling conditions when non-destructive tests such as rebound hammer and surface deflection test are applied to concrete pavement. METHODS : Nondestructive tests using Schmidt hammer and Falling Weight Deflectometer were performed to inspect the expressway concrete pavements constructed more than 20 years ago. Some results were compared with core tested elastic modulus and compressive strength. RESULTS : As a result of the rebound test, the section with Alkali-Silica Reaction(ASR) distress was outside the range of the existing estimation formula, but the control section was found to be within the range of the existing estimation formula. As a result of the physical property estimation through deflection test, the section with ASR distress showed greater fluctuations in the estimated material properties and deflection ratio compared to the control section, showing that the ASR damage seems to affect the slab deflection behavior. CONCLUSIONS : The rebound test may not sufficiently reflect the decline in material properties due to concrete damage. The deflection test can obtain results that reflect the deterioration of material properties, but it was confirmed that significant variability may occur, so it seems to necessary to perform complementary indoor core tests with nondestructive testing(NDT) tests.

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 : 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.

본 논문은 고준위폐기물 처분시스템에서 공학적방벽의 열-수리-역학적(Thermal-hydraulic-mechanical) 복합거동 실증을 위 In-DEBS (In-situ Demonstration of Engineered Barrier System) 를 개발하여 구축하는 과정에 대해 설명한다. 공학적방벽은 크게 처분용기, 완충재 그리고 근계암반으로 이루어져 있는데, In-DEBS는 완충재 및 근계암반을 대상으로 지하수 유입 및 처분용기의 발열에 의한 THM 복합거동을 분석할 수 있도록 설계되어 있다. In-DEBS 현장시험은 A-KRS의 1/2.3 규모로 설계되어 있기 때문에 처분공의 지름이 약 860 mm로 작게 굴착하였다. 따라서, 처분공 안에서 센서와 히터를 삽입하면서 완충재 블록을 조립하는 것은 힘들기 때문에 완충재 블록 일체형 설치 틀(OBPA)를 개발하여 외부에서 모두 조립하였다. 완충재블록, 센서 및 히터가 조립 완료된 일체형 설치 틀은 총 무게가 약 3톤으로 매우 무겁기 때문에, 처분공에 정확히 삽입하기 위해서는 특별한 운송기구가 필요하다. 본 연구에서는 레일을 이용하여 5톤 이상의 무게를 들어서 정확한 위치에 정치 시킬 수 있는 In-DEBS 전용 크레인을 개발하여 조립완료된 완충재 블록을 삽입하였다. 근계암반의 THM 복합거동을 분석하기 위해 In-DEBS 주위로 4개의 시험공을 굴착하여 총 40개의 온도 센서와 5개의 간극수압계를 설치하였다. 또한 근계암반의 변위를 측정하기 위해 원거리에서 두 개의 경사공을 굴착하여 총 10개의 변위 센서를 삽입하였다. In-DEBS에는 공학적방벽시스템에 온도, 상대습도, 압력, 그리고 변위 센서 등 총 185개의 센서가 설치되어 있으며, 이 센서들은 모두 다채널 동시 측정이 가능한 계측시스템에 연결되어 실시간으로 현장데이터를 저장하게 된다.

선진핵주기고준위폐기물처분시스템(A-KRS, Advanced Korean Reference Repository System)을 기반으로 한 공학규모 공학적방벽시스템 열-수리-역학적 복합거동 현장시험(In-DEBS, In-situ Demonstration of Engineered Barrier System)은 2012년부터 기획되었다. 한국원자력연구원의 자체기술로 전체 시스템 구성요소를 설계하고 제작하여 2016년 5월 한국원자력 연구원의 지하처분연구시설(KURT, KAERI Underground Research Tunnel)에 설치하였다. 2016년 7월에 정상운영을 시작하여 현재까지 양질의 열-수리-역학 데이터를 생산하고 있다. 이 시험은 국내에서 최초로 설치하여 운영되는 고준위폐기물 심층처분시스템 공학규모 현장시험으로써, 대규모 공학적방벽 제작기술 개발 및 검증, 처분시스템 설치방법 개발 및 검증, 국내산 벤토나이트의 장기 열-수리-역학 거동 자료 확보, 공학적방벽 국내산 벤토나이트 완충재의 열-수리-역학(THM, thermal-hydro-mechanical) 복합거동특성 현장시험 및 THM 복합모델링 기술 검증, 공학적방벽 완충재 THM 특성 측정 및 모니터링 기술 개발 등을 통한 국내 고준위폐기물 심층처분시스템 공학적방벽의 성능검증 기술개발을 최종 목표로 하고 있다. KURT 기반 In-DEBS의 성공적인 설치와 운영을 통해 공학규모 공학적방벽의 제작 및 설치 기술을 확보할 수 있을 뿐 아니라 여기에서 생산되는 데이터를 이용하여 처분기술개발의 핵심 분야인 공학적방벽 THM 복합모델링 기술의 개발 및 검증 능력도 갖추게 될 것이다. 따라서 향후에 수행될 우리나라 고유의 실규모 처분시스템 실증기술 개발을 위한 귀중한 정보를 제공해 줄 것으로 기대된다.