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.

2020년 3월부터 10월까지 군산시의 중초산 저수지와 북초산 저수지의 어류상 및 군집분석을 하였다. 조사기간 동안 채집된 어류는 중초산 저수지에서 4목 5과 8종 1,895개체, 북초산 저수지에서 3목 5과 7종 171개체였다. 중초산 저수지의 우점종은 참붕어 (661개체, 상대풍부도: 34.7%) 아우점 종은 흰줄납줄개 (660개체, 상대풍부도: 34.7%), 북초산 저수지는 배스 (77개체, 45.0%)와 붕어 (60개체, 35.1%) 순으로 나타났다. 군집분석 결과 중초산 저수지는 우점도 0.697, 다양도 1.483, 균등도 0.713, 종 풍부도 0.928, 북초산 저수지는 우점도 0.801, 다양도 1.304, 균등도 0.670, 종 풍부도 1.167을 보였다. 본 연구 결과를 통해 생태계 교란생물인 배스의 영향으로 토착어종의 개체수와 군집의 다양도가 감소한 것을 확인할 수 있었다. 따라서 외래어종의 지속적인 제거와 유입을 막는 관리가 요구된다.

PURPOSES : This study analyzes the service life of the repair methods of jointed plain concrete pavement (JPCP) on expressways in Korea using PMS data. METHODS : The Korea Expressway Corporation PMS data acquired from five major expressways in Korea were used for the analysis. The service lives of the repair methods were considered for two different cases: 1) the previous repair methods had been completely rerepaired by another or the same method due to their damage, and 2) the current repair methods were still in use. RESULTS : The service lives of D/G and section repair were shown to be at least 30 % and 50 % shorter than expected, respectively. Joint sealing and crack sealing exhibited a service life similar to that expected. The Mill-and-Asphalt-overlay method showed an approximately 30 % longer service life; this might be because some damage to the asphalt overlay is typically neglected until subsequent maintenance and repair. When multiple repairs were applied in series for an identical pavement section, the service life of repairs on previously damaged secti ons become even shorter compared to their first application. CONCLUSIONS : It was found that the analyzed service life of most important repair methods did not reach the expected service life, and that the service life of the same repair method becomes shorter as applied to the previously repaired concrete pavement sections. These shorter service lives should be seriously considered in future JPCP repair strategy development.

미국가재는 멕시코 북동부 및 미국 중남부가 원산지로, 전 세계에 유입되어 서식처 파괴와 토착종과의 경쟁 등 많은 문제를 야기하고 있다. 본 조사에서 영산강 6개 지점, 만경강 5개 지점, 섬진강 2개 지점 금강 1개 지점에서 확인되었으며, 주요 수계에서 정착 서식하는 것으로 나타났다. 완주군 서봉리와 함평군 모산리는 20개체 이상이 확인 되어 비교적 큰 개체군을 형성하고 있을 것으로 추정된다. 높은 이동성과 환경적응력으로 보아 확인된 지점에서 타 수계로의 유입 가능성이 매우 높을 것으로 생각되며, 이에 지속적인 확산 현황 파악과 생태계 피해 예방을 위한 지속적 제거 노력이 필요하다.

PURPOSES: Spalling is one of the primary problems that lead to the damage of concrete pavements. The purpose of the study is to analyze the impact range of spalling that occurred in an area of concrete pavement by applying a variety of nondestructive and destructive testing methods. METHODS: Spalling of the concrete pavement was categorized into four different sizes, 0 cm, 7.5 cm, 15 cm, and 30 cm. Nondestructive and destructive tests were performed at the point of spalling and 1 m away, respectively, and the obtained results were compared. The nondestructive tests included the electrical resistance test and the ultrasonic velocity test as well as strength tests by Schmidt hammer and concrete tester. The destructive tests included the direct compressive strength test and the chloride content test using field cored specimens. The test results helped in the analysis of the correlation between the current spalling damage condition and the expected damage acceleration. RESULTS: Based on the present study, the repair area and depth of spalling for a partial depth repair was suggested. It was also shown that the size of the spalling is highly correlated with the chloride content and the electrical resistance of the concrete pavement. CONCLUSIONS: The degree of spalling deterioration was found to be highly correlated with the chloride content and electrical resistance of the concrete pavement and based on the results, the extent of repair could be determined more quantitatively.

PURPOSES : The frequency and severity of natural disasters such as torrential rain or typhoons have become increasingly significant worldwide. Events such as summer typhoons and localized torrential downpour can cause severe damages to a residential area and road networks, resulting in serious harm to the daily lives of people, especially in rural areas by isolating residents from road networks. An immediate and emergency repair technology for the collapsed road networks is urgently needed. This study introduces a new technology to repair road bases or slopes. METHODS: The development of new technology for emergency and permanent repair consists of first, packing of cement paste-coated gravel, second, combining appropriate equipment, and third, conducting a field applicability test. In this research, the compressive strength of cement pastecoated gravel, gravel-netting concrete properties, and packing efficiency were determined, and a full scale field mock-up test was carried out. RESULTS : The compressive strength of the cement paste-coated gravel concrete satisfied the required limit for road base of 5 MPa after 7 days. With appropriate netting materials and packing size, gravel-netting concrete was successful up to a slope of 1:1.5. The full scale field mockup test showed efficiency in the field and penetration resistance performance. CONCLUSIONS: The new technology of emergency and permanent repair for damaged road bases and slopes, introduced in this study, showed satisfactory performance. The technology is expected to be applied in the field when construction procedures and quality specifications are made.

PURPOSES: The occurrence of unexpected disasters, including fire events, increases as the road network becomes complicated and traffic volume increases. When a fire event occurs on and under bridges, the damage extensively influences direct damage to structures, vehicles, and human life and secondary socioeconomic issues owing to traffic blockage. This study investigated potential fire-hazard risks on bridges of the Korean national route roadMETHODS: The investigation was conducted using field investigation and analysis with satellite pictures and road views from commercial websites and the Bridge Management System (BMS). From the filed investigation, various potential fire resources were identified. The satellite pictures and road views were helpful in measuring and recognizing conditions underneath bridges, stowage areas, etc.RESULTS : There are various potential fire resources underneath bridges such as piled agricultural products, parked petroleum tanks, construction equipment, and attached high-voltage cables. A total of 94.6% of bridges have underneath clearances of less than 15 m. A bridge underneath volume that can stow a potential fire hazard resource was 7,332 m3 on average, and most bridges have about 4,000 m3 of space. Based on the BMS data, the amounts of PSC and steel girders were 29% and 25%, respectively.CONCLUSIONS : It was found that the amount of stowed potential fire hazard resources was proportional to the underneath space of bridges. Most bridges have less than 15 m of vertical clearance that can be considered as a critical value for a bridge fire. The fire risk investigation results should be helpful for developing bridge fire-protection tools.

최근 호우 및 산사태 등 자연재해로 인한 도로유실 피해가 증가하고 있으며, 특히 지역특성상 산림이 많이 분포된 지역은 피해가 큰 실정이다. 또한, 유실부 긴급복구 방법은 일시적 교통개방이며, 지속된 교통개방이 어려운 상태이다. 이에 본 연구에서는 도로유실 긴급복구를 위한 연구의 일환으로 골재망을 활용한 다공질 콘크리트 긴급복구 공법의 장비조합을 제안하고자 하였으며, 최소한의 장비로 현장배합 및 도로유실 긴급복구에 활용하고자 한다. 장비, 재료 운반 및 하차수단으로 카고크레인 및 일반 적재트럭으로 2식의 차량을 제안하며, 운반 구성은 현장배합용으로 시멘트, 몰탈믹서, 1㎥물통과 유실부 복구를 위한 골재망, 시멘트페이스트 적재 박스와 골재망 적치는 카고크레인으로 대처하며, 현장지반정리용 0.2B/H, 다공질콘크리트 일부다짐용 콤펙터를 활용하였다. 그림1 및 그림2는 제안한 2식의 차량으로 활용되는 계획을 각각 나타내며, 그림3은 제시한 장비조합의 긴급복구 계획을 나타내고 있다. 도로유실 긴급복구 골재망 활용 다공질 콘크리트의 현장배합 및 시공을 위한 장비조합을 제시하고자 하였으며, 이에 따른 결과는 다음과 같다. 1) 제시한 장비조합은 대형 중장비가 아닌 중 · 소형 장비, 재료로써 운반 및 사용이 용이하며, 신속하고 항구적인 골재망 활용 다공질콘크리트 긴급복구 공법에 적합하다 판단된다. 2) 제시한 장비조합은 Mock-up시험 등을 통한 검증필요가 예상되며, 유실위치 및 규모에 따른 추가 장비구성 및 시공방법 변경에 대한 추가적인 계획이 필요할 것으로 사료된다.