• Journal of the Korean Recycled Construction Resources Institute
• /
• v.11 no.4
• /
• pp.458-466
• /
• 2023

Structures in our surroundings deteriorate over time due to environmental and chemical factors, resulting in a decrease in their performance. The primary causes of degradation in concrete structures are carbonation, salt damage, and freeze-thaw cycles. Various maintenance methods exist to address these degradation issues. However, research and technological development for existing maintenance methods have been ongoing, but the accuracy and effectiveness of repair materials and techniques have not been extensively validated. Therefore, in this study, we conducted a material performance evaluation of various manufacturers' repair materials. Based on this evaluation, we applied corrosion inhibitors and epoxy, which are the methods most closely related to crack repair, to assess the durability performance against carbonation, salt damage, and freeze-thaw cycles. The results show approximately a two-fold performance improvement against carbonation and salt damage, and a 5% enhancement in repair performance against freeze-thaw cycles. Thus, it is considered effective in preventing rebar corrosion when appropriate maintenance is carried out according to environmental and chemical factors during structural repairs.

• Earthquakes and Structures
• /
• v.15 no.2
• /
• pp.165-178
• /
• 2018

The aim of this study is to investigate the efficiency of using threaded rods and steel profiles to produce a steel confining system for rehabilitation of damaged concrete corbels for the first time in literature. Some of the specimens were repaired by crack repair epoxy before being confined for further enhancement. A total of 19 two sided damaged corbels were used in the study with different mechanical properties and parameters but similar dimensions. The differences were in rehabilitation style, shear span, fiber percentage, reinforcement steel diameter, and concrete strength. The rehabilitated specimens were loaded with vertical load until failure. Four different configurations were used in the investigation. Test results show that the proposed rehabilitation technique is effective to enhance the load capacity of the corbels and to improve their ductility. Moreover, new formulations were proposed to calculate the load capacity of the rehabilitated corbels. A good fit was observed between numerical and experimental results.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1997.10a
• /
• pp.647-652
• /
• 1997

Repair and rehabilitation of existing structures is becoming a major part of construction, both in the industrially developed and developing countries. Advanced high strength composites are being utilized more and more for these applications because they are much stronger than steel, non-corrosive, and light. The light weight reduces the construction cost and time sustantially. The fibers are normally made of aramid, carbon, or glass and the binders are typically epoxies or esters. One major disadvantage of these composites is the vulnerability to fire. In most instance, the temperature cannot exceed $300^{\cire}C$. Since carbon and glass can substain high temperatures, an inorganic polymer is being evaluated for use as a matrix. The matrix can sustain more than $1000^{\cire}C$. The results reported in this paper deal with the mechanical properties of carbon composites made with the inorganic polymer and the behavior strengthened reinforced concrete beams. The results indicate that the new matrix can be successfully utilized for a number of applications.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.05a
• /
• pp.947-952
• /
• 2002

Recently, there have been increased much concerns about repair and rehabilitation works for aged concrete structures. In particular, it is known that due to repeated overburden vehicle there are significantly increasing number of aged concrete bridge slabs, which are strongly needed to construct and rehabilitate by innovative construction method. The objective of this research is to develop the new construction method of concrete slab in bridge structure, which can contribute to minimize the traffic congestion during the repair and rehabilitation works of aged concrete slab, and can also sufficiently assure the quality through the minimization of in-situ works at the site. I-beams with punch holes, which are substituted instead of main reinforcing steels in concrete slabs, will be manufactured in accordance with the specification in the factory, and will be preassembled into the panel. After erecting the preassembled panels in the site, concrete will be poured into the slab panel. This research is to investigate physical properties of I-Beam concrete slab through static test.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.04a
• /
• pp.458-463
• /
• 2000

Recently, there are increasing much concerns about repair and rehabilitation works for aged Concrete Structures which had been constructed on around the 1970's for rapid economic growth in Korea. In particular, it is believed that there are many aged concrete slabs for Highway bridges in these days. Thus new construction method of concrete slabs are strongly needed to minimize the traffic congestion during the repair works. The objective of this research is to develop the new constructional method of concrete slab in bridge structure, which can contribute to minimize the traffic congestion to be occurred during the repair and rehabilitation works of aged concrete slab, and can also assure the reliable quality through the minimization of in-situ works at the site. I-beams with punch holes will be manufactured in accordance with the specification in the factory, and will be preassembled into the panel. After erecting the preassembled panels in the site, concrete will be poured into the slab panel. This research is to investigate physical properties of I-Beam with punch holes itself, and then to investigate structural properties of assembled I-Beam panels through static and fatigue test, of which result can be utilized for the development of the new constructional method for concrete slab in bridge structure.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.21 no.5
• /
• pp.148-155
• /
• 2017

In this study, by using the international standards ISO TS 16774, Part 2 Test method for chemical resistance as a quality control method of injection type repair material used for leakage crack of underground concrete structure, the performance requirement against of chemical environment of underground concrete structures for repair materials was tested. For this testing 3 types for each of the 2 classes of repair materials(synthetic rubber, cement), with a total of 9 types repair materials, were selected and examined. As a result, the test results showed that the smallest performance deterioration by the change in the mass was with the synthetic rubber(RG) type as opposed to the cement type system, showing that the synthetic rubber type had the strongest relative resistance to chemical exposure. Furthermore, it is necessary to investigate the material with high resistance to chemical substances and to examine the material which can increase resistance to sodium hydroxide and sodium chloride in cement system. These results can be used as a basic index for the selection of repair materials with the strongest resistance to chemical environment found in concrete structures. In addition, it is expected that the test results derived in this study can be used as reference data that can be reflected in the quality improvement of the maintenance material to be developed later.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.04b
• /
• pp.633-636
• /
• 1998

This study is performed for the purpose of obtaining the fundamental datum to analyse the cause of steel corrosion in concrete and establish the repair strategies of deteriorated reinforced concrete structures due to steel corrosion. To investigate the degree of concrete deterioration, soluble chloride content in harden concrete, the depth of carbonation, cover depth and compressive strength are measured. The progress of corrosion of concrete bridge is electrochemically evaluated. The result shows that in approximately 43% of the structures below -350mV(vs. CSE), the exessive chloride contents is a direct cause of steel corrosion in reinforced concrete structures.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.05a
• /
• pp.437-442
• /
• 2001

Recently, there have been increased much concerns about repair and rehabilitation works for aged concrete structures. In particular, it is known that due to repeated overburden vehicle there are significantly increasing number of aged concrete bridge slabs, which are strongly needed to construct and rehabilitate by innovative construction method. The objective of this research is to develop the new construction method of concrete slab in bridge structure, which can contribute to minimize the traffic congestion during the repair and rehabilitation works of aged concrete slab, and can also sufficiently assure the quality through the minimization of in-situ works at the site. I-beams with punch holes, which are substituted instead of main reinforcing steels in concrete slabs, will be manufactured in accordance with the specification in the factory. and will be preassembled into the Panel. After erecting the preassembled panels in the site, concrete will be poured into the slab panel. This research is to investigate physical properties of I-Beam with punch holes itself through static and fatigue test with rational numerical analysis Finally this research is to suggest reformed I-beam through the numerical analysis.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.05b
• /
• pp.409-412
• /
• 2005

Because the underwater structures are subjected to the deterioration according to use environment, it is necessary to repair and reinforce when the durable performances are considered in structures. In generally, epoxy mortar is used to repair materials of underwater concrete. It is divided epoxy and filler which is organized cement and sand. Cement can be replaced by stone powder sludge in waste because the grading of stone powder sludge in drying state has similar to that of cement. As result of study, it is possible that stone powder sludge can be applied for replacement materials of cement in epoxy mortar, because the strength is not different when filler in epoxy mortar is alternated stone powder sludge.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.05a
• /
• pp.151-154
• /
• 2005

One of the most important characteristics of Engineered Cementitious Composite (ECC) is its strain hardening behavior up to $5\∼6\%$of stain under a tensile loading. So, the ductile behavior of ECC should be utilized in applications to maximize the performance of structures. Thus, in this study, the ductile behavior of ECC as a repair material applied to the tensile region under flexural loads is numerically examined using a developed numerical model. Several strain capacities of ECC are examined to predict the behavior of ECC strengthened flexural structures. The results show that a certain optimal level of ductility in ECCs for repair applications exists and it is an important factor to consider when using ECC as a repairing material.