PURPOSES : The purpose of this study is to suggest the construction and quality control method for the re-repair of a deteriorated partial depth repair for sections of Portland cement concrete pavement. METHODS : An experimental construction was conducted to extend the repair width for removing an existing repair section. A removal method was used to ensure early performance for a deteriorated partial depth repair section. Bond strength and split tensile strength were measured at the near vertical interface layer between the existing pavement and repair material. The area was analyzed for various conditions such as the extended repair area and the removing method of the existing repair section. RESULTS : As a result of analysis of bond strength and split tensile strength, the bonding performance of a milling removed section was improved over a cutting and hand breaker removed section. The bond strength was analyzed to increase slightly as the extended repair width for removing the existing repair section increased. The split tensile strength did not show a clear relationship to an increased extended repair width of an existing removed repair section. CONCLUSIONS: The milling removal method should be applied in the removal of existing deteriorated partial depth repair sections. The extended repair width for a re-repair section should be wider than the existing partial depth repair with at least a 75-mm length and width for the bond strength and the split tensile strength.

This study was carried out to improve the performance of sewer trenchless entire repair method by using the multifunctional safety high-pressure hose. Because the flexural strength and flexing modulus of elasticity increased in the range from 60℃ to 80℃ of the setting temperature, the unform quality was secured to satisfy the standard quality and consolidate the strength, by supplying steam to the entire sewer through the safety high-pressure hose simultaneously. After the steam was supplied, the temperature of the condensate water with a large amount occurred , compared with a small amount, was very low. So, the setting time was shorter over than one hour by reducing the unsatisfied cure state and excluding the condensate water. The standard quality increased by approximately 15% at upper, central, and lower points of the same sewer was gained from the test result of CIPP(cured in place pipes) constructed at the optimum setting temperature. The steam and air were supplied evenly to the sewer by controlling the safety high-pressure hose in the tense and relaxed state and by using the exclusive function of condensate water. The availability and safety for the constructed process were achieved.

This study considers the proper repair techniques by examining the most representative repair cases of the Korean arch bridges and proposes the constructional manual which can apply similar occasions. The cases are Seonamsa Seungseongyo and Songgwangsa Geukrockgyo where this researcher had taken part in the repair works. This Study proposes the maintenance construction manual about the performance degradation drew by performance degradation of the both Korean arch bridges in the maintenance process. First, arch bridge maintenance should be carried out in the dry season, when water is impermeable in the bottom surface of the bridge. Moreover, risk factors of the maintenance should be excluded to secure the water vally flow, the bypass and the temporary bridge. Second, prior to repair, it has to precede ①3D shooting ② formal examination ③structure safety test ④geological and lithic surveys ⑤arch curvature establishment and makeshift frame settlement before transformation ⑥relationship expert comments. Third, if the baduk and the foundation stones are inevitable to replace due to performance degradation on the foundation, it should use the high quality stones and secure greater stress by extending the standard range. The foundation on irregular rock needs to be flattened and underside on the replaced materials require Grengyijil to deliver the equal loads. Fourth, In the process of dismantling the stones of the arched bridge, it could make heavy weathering degree and not reuse the materials. Charge should converge the expert advices to choose the reuseable, the conservate and the alternative materials, and increase the reutilization of the raw materials by preservation and reinforcement treatments. Fifth, the side wall should be repaired by the rubble work technique which is not able to pile compost satiety, so it must use long depth of masonary stones for reinforcement. It is considered to reinforce the stone wall in shore as much as possible and protect the abutment and the side wall on the upstream for the arch bridge maintenance works.

기계식 신축이음장치는 온도변화, 크리프 등에 의한 상부구조 수평변위를 수용하고 불연속면을 연속화시켜 차량의 주행을 원활하게 하는 교량부속장치이다. 하지만 윤하중의 직접재하 및 제설제 등에 노출되어 신축이음장치의 파손, 후타콘크리트 균열 및 탈락 등 많은 문제를 동반하고 있다. 이러한 신축이음장치는 교량 공용기간 중 약 10년 주기로 교체 공사가 필요한 소모성 구조부재이며 매년 동일한 수준의 국가 예산이 지출되고 있는 실정이다. 이에 본 연구에서는 기존의 신축이음 교체 공사 시 기존 교량에 무조인트 교량 시스템을 도입하여 유지관리 비용을 저감할 수 있도록 하였다.

In reinforced concrete structures, carbonation phenomena associated with deterioration is important. So, this study conducted a visual inspection and a concrete durability test in Precise Safety Diagnosis, analyzed the result, and tried to suggest a reasonable repair method and range of concrete carbonation.

reinforced concrete structures, carbonation phenomena associated with deterioration is important. So, this study conducted a visual inspection and a concrete durability test in Precise Safety Diagnosis, analyzed the result, and tried to suggest a reasonable repair method and range of concrete carbonation.

The leak issues that arise in the 2-Arch Tunnel are caused by groundwater being trapped in the central pillar portion. Therefore, the most reasonable repair method should be suggested after the analysis of what causes the leak.

Highway construction to the reinforced earth retaining wall which is under constant traffic load there is a possibility of generating the displacement at the top. In this study, it was conducted determine how to repair reinforcement method through examination of cause and stability analysis when occurs the displacement of reinforced earth retaining wall.

The priority order about a rational repair and reinforcement is generally decided by subjective decision of engineer. An appearance investigation carried out to decide about a rational repair and reinforcement through systematic and objective analysis in tunnel. we could prevent expecting leakage through several improvements in the aspects of design, materials and site implementation.

The priority order about a rational repair and reinforcement is generally decided by subjective decision of engineer. An appearance investigation carried out to decide about a rational repair and reinforcement through systematic and objective analysis in tunnel. we could prevent expecting leakage through several improvements in the aspects of design, materials and site implementation.

Restraint to drying shrinkage is the most common cause of concrete cracking. In many applications, drying shrinkage cracks are inevitable. In this paper, the surface cracks of soil concrete caused by drying shrinkage were considered to become an one of concrete textures. So, laboratory shrinkage tests were conducted and the results were applied to the field applications. The study results were summarized as follows; First, the use of vinyl sheets and concrete polymers helped to control the concrete cracking. Second, crack propagation usually started at the interfaces of soil concrete slabs and the cracks grew to the inner slabs. Third, surface cracks of soil concrete slabs could be an one of good concrete textures.

본 연구에서는 RC구조물의 내구 및 내화성능을 동시에 향상시킬 수 있는 고인성 모르타르 (FR-ECC)를 개발하여, 이를 RC구조물의 보수재료로서 사용하기 위한 실험적 연구를 실시하였다. 즉, FR-ECC를 이용하여 제조한 콘크리트 시험체의 강도, 열적특성, 모의부재의 철근부식특성, 내화성능 등에 대하여 검토하였으며, FR-ECC의 현장적용 가능성에 대해서도 평가하였다. 그 결과, FR-ECC는 기존 보수 모르타르에 비해 우수한 강도 및 내구성능을 보유하고, 휨균열 발생 후에도 외부열화 인자의 침입을 억제하여 철근부식을 방지하는 것으로 나타났다. 또한 FR-ECC를 적용한 부재는 ISO 834 가열조건에서도 우수한 내화성능을 갖는 것으로 나타났으며, 뿜칠성능 등의 현장시공 성능에서도 우수한 특성을 나타냈다.