In this study, the tendency of flow characteristics according to the mixing design of mortar and mortar standard reference materials was analyzed based on the constituents of the standard reference materials for mortar. As a result, the plastic viscosity of the mortar tends to be maintained according to the amount of fine aggregate, while the yield value tends to increase greatly. On the other hand, in the case of the standard reference materials for mortar, the plastic viscosity tends to increase largely according to the amount of fine aggregate substitutes, while the yield value tends to be almost maintained.

In this study, the behavior and ductility characteristics of fiber reinforced concrete was experimentally conducted under high and low temperature conditions. The results showed that the ductility index was increased with temperature increase.

This study describes the applicability of machine learning techniques using the measurements of non - destructive testing techniques to identify the strength of concrete in the current state and to predict future strength. We also want to develop analytical techniques suitable for the strength evaluation of concrete among various machine learning techniques.

In this study, the crack healing performance of concrete containing microbial - based self - healing agent for the purpose of crack crack healing was evaluated by the permeability test. As a result of the addition of the microbial culture solution to the mixed water at an alternative ratio, the permeability recovery rate increases as the substitution rate increases. It is necessary to develop a microbial concentrate and to study the application of mixed microorganisms for the purpose of increasing the rate of permeability recovery and decreasing the substitution rate of microbial solution.

In this study, basic research was carried out to improve the absorption rate which is a problem in increasing the recycling rate of recycled fine aggregate and to improve the usability as concrete aggregate. It was confirmed that the absorption rate of the recycled aggregate measured after immersing in the microbial culture solution for the purpose of improving the absorption rate of the circulating fine aggregate for concrete was decreased. However, further studies such as improvement of microbial culture are required to satisfy KS standards.

The rheological properties of concrete vary during pumping. In this study, the tests were conducted to evaluate whether changes in rheological properties of concrete during pumping occur only by pressure, or by both pressure and shear flow. A high-strength concrete with a design strength of 50 MPa was used in the experiment. From the test results, it was confirmed that the change of rheological properties of concrete during pumping was affected by both pressure and shear flow.

In this paper, water flow test was performed to evaluate the healing performance of self - healing solid capsules based on inorganic materials. The water flow test was used to evaluate the permeability reduction for each healing age with respect to the initial permeability of crack - induced test specimens.

본 연구는 50mm 길이의 SD400 12mm 철근을 수돗물, DW + 10% CaCl2와 금속 + DW + 10% CaCl2 총 세종류의 액체에 넣어 가속 부식을 시킨 후 가속화에 따른 철근 산화물의 변화를 주기적으로 관찰하여 각각 철근의 부식으로 인해 생겨나는 화학물질을 분류하고, 변화하는 실험 조건이 주는 영향도 같이 비교하였다. 실험 결과 가속 부식 시킨 철근 산화물의 구성 요소들은 Iron Carbon – CFe15.1, Lepidocrocite – FeO(OH), Magnetite – Fe3O4, Wustite – Fe0.942O 등이라는 것을 확인할 수 있었으 며 그 변화를 그래프로 나타내었다.

Mechanical properties of concrete such as compressive strength and elastic modulus are affected by the moisture inside the concrete members. Concrete specimens with various diffusion conditions are tested and the relations between the pore relative humidity and mechanical properties are suggested based on the experimental results. Suggested models are applied to the experimental results in the previous researches and the comparison results show that the models are reasonable.

This study introduces a decision-making support method for maintenance activities of bridges after earthquake. A seismic damage prediction system for bridges which do not have seismic acceleration sensors was developed to support the maintenance activities. The system consists of two main modules, one is seismic load estimation module based on the data from seismic stations and the other is seismic damage prediction modules based on the finite elements analysis models for seismic analysis. After verifying the prediction system for the damaged bridges after Po-Hang Earthquake, it was found that the system was able to predict seismic damages of bridges enough to make a decision of maintenance activities.

최근 대규모 지진으로 내진 성능 및 보강에 대한 정부와 국민들의 관심이 높아지고 있으며, 재난관리 시장이 사후복구에서 사전예방중심으로 재편됨에 따라 시설물의 물리적인 상태등급만을 고려하는 기존의 결정론적 내진성능관리 의사결정기술에 지진의 불확실성 및 사회·경제적 판단요소와 도로망 시설물의 네트워크 시스템을 고려한 확률론적 내진성능관리 체계 확립이 필요하다. 결정론적 방법에 의한 도로시설물 내진성능관리 우선순위는 물리적인 상태등급에 따라 결정되며, 사회·경제적 판단요소가 결여되어 있어 전체적인 판단을 할 수 있는 근거를 제공하지 못하고 있는 실정이다. 도로시설물 내진성능관리 우선순위에 대한 의사결정을 위해서는 도로의 중요도, 노후거동특성, 부재 내진성능, 지진취약도 함수, 내진보수보강효과, 지진복원력 등과 같이 도로시설 및 도로망에 직·간접 적으로 가해지는 물리적, 사회적, 경제적 영향을 평가할 수 있는 의사결정지원 기술이 부재한 실정이다. 따라서 노후도에 따라 지진취약도가 크고 재난 발생 시 파급영향이 큰 도로시설물과 도로망을 식별하기위한 합리적이고 체계적인 내진성능 관리 핵심기술개발이 필요하며, 본 논문에서는 연구단 과제를 통해서 개발예정인 “노후도로망의 내진성능관리 의사결정 알고리즘”을 소개하고자 한다.

As the road sink phenomenon occurred continuously at the center of seoul in 2014. The road sink phenomenon was emerged as a social big issue in korea. So far, government, municipalities and related experts have been making a lot of efforts to prevent road sink accident, but it is still happening all over the country. Therefore, In this study aims to present the restoration action procedures and checklist items that can be used by government officials in order to recover quickly in the event of a road sink.

Recently, the slope failure, which is frequently happened in Ice-melting season, attracts attention in South Korea. The increasing trend in frequency of freezing-thawing process has regarded as major reason of slope failure. However, the time and check level are not reflected at the safety assessments and inspection guidelines. Therefore, the characteristics of slope in ice-melting season should be considered to improve the slope stability in ice-melting season. The purpose of this study is to evaluate the influence of the potential risk factors on the slope stability for development of the slope checklist reflecting the timing and check level based on the slope inspection checklist which is provided by the recent research.

A damage case of parallel strand cable anchorage was introduced, in which 7 strands were slipped from each wedge at the anchorage of the cable stayed bridge in service. Also, a cable damage detection scheme was proposed on the basis of tension force measurement and model updating method by least square estimation to minimize tension variation. The proposed scheme has been verified from analytical simulations and the actual damage case. The damaged cable leading to tension variation more than noise level of cable force measurement was successfully detected with 7~8 strands damage indication of 2% error in the actual strand slippage case.

The wireless sensor prototype was developed and the field test result, natural frequencies of each mode in stay-cable, showed 0.5% difference compared to the wired sensor. Also, the cable tension derived by the vibration method was 1.177% difference. As a sensor for managing cable tension, the applicability to bridges was confirmed. In the next study, LoRa LPWAN technology will be applied to various sensors used in structures.

In this study, the maintenance techniques of expressway geotechnical structures have been reviewed for the last 50 years. And, throuth this, necessary maintenance technology was derived in the future. As a result, the maintenance of the geotechnical structures was mainly developed for slope structures. And slope information system, alarm system, etc. have been developed and applied. In the future, technological advancement will be achieved by applying the 4th industry revolution technology.

The inspection items of tunnels include road surface breakage and cleaning condition, lane paint condition, lining crack, leakage, corrosion condition, tile cleaning condition, daylight and nighttime optimum illuminance condition, drainage facility damage and cleaning condition, Gangway wall wall and retaining wall abnormality, slope top and side slope condition. However, investigations for maintenance of tunnels mainly consisted of surveying condition and durability of concrete lining due to characteristics of tunnels.

Korea Expressway Corporation has been in operation for 50 years. Bridges have increased due to the construction of expressways. As the use of bridges continued to become obsolete, the organization and budget increased accordingly. Inspection techniques have also been upgraded. In this paper, the changes in the maintenance of expressway bridges are summarized in terms of the status, organization, budget, inspection technique, maintenance and reinforcement, and history management system.

Korea Expressway Corporation has been in operation for 50 years. Pavement maintenance, which was initially conducted by manpower, reached its limits due to the increase of highway extension. Therefore, the introduction of the pavement management system in the 1990s was considered. The pavement management system has become the foundation for conducting the budget. In the 2010s, the concentrated maintenance system, which closes traffic for a long time, was being applied to efficiently manage the distressed pavement.

This Prospect and Technological Prediction established a strategy system for '2050 Future Highway' to propose the direction of the overall development of highway industry and technology and to secure sustainability. It set future tasks to be implemented in the '2050 Future Highway' suitable for the strategy, materialize detailed measures and identify promising future technology. Also, promising future technologies were evaluated for the possibility of successful technological development, creative innovation, significance of each technological element (comprehensive) and the need for governmental investment based on the Delphi research, and from this, top 50 technologies were selected by considering the balance between tasks for future vision system.