• Journal of the Korean Society of Hazard Mitigation
• /
• v.8 no.5
• /
• pp.65-70
• /
• 2008

Asphalt concrete pavements are susceptible to deformation and failure compared to cement concrete pavements. Epoxy is commonly used to enhance the bonding and durability of structures. Based on this concept, an epoxy and ceramics combined mixture was developed and applied to the field to estimate the pavement performance, Laboratory and field performance tests were conducted to observe the applicability of epoxy and ceramics composite materials compared to the conventional one. In this research, the epoxy and ceramics composite mixturewas used in two ways. 7 mm and 15 mm of thin surface layers using the mixture were constructed on cement and asphalt concrete pavements, respectively, after surface treatment. 12 months of field performance surveys were conducted to observe the resistances to the crack and deformation. According to the field performance tests, epoxy and ceramics combined mixture showed better bonding and field performances than the conventional one.

• Journal of the Korean Geosynthetics Society
• /
• v.5 no.3
• /
• pp.1-7
• /
• 2006

The Green Wall system, developed in Austria early 1960, is one of segmental concrete crib type earth retaining wall. Green wall is constructed as procedures that lay the front stretchers, rear stretchers and headers then making a rigid body through harden filled soil of interior cell. Green wall has pro-environmental advantages that able to grow grass in front space of stretchers and decrease cutting ground. In Europe, Green wall used without other reinforcement method. However, green wall used with other reinforcement method like a soil nailing because of environmental problem. This study was performed to introduce the design case by 'Two-Body Translation mechanism' to be able to consider distribution of earth pressure in the soil nailing when designing the green wall using soil nailing system. Also, this study attempts to evaluate the earth pressure change when advanced soil nailing system is constructed using $FLAC^{2D}$ ver. 3.30 program and 'Two-Body Translation mechanism'.

• Explosives and Blasting
• /
• v.28 no.2
• /
• pp.76-85
• /
• 2010

In this paper, we present the result of an analytical investigation concerning the demolition range for the pre-weakening of load-bearing wall in explosive demolition. Pre-weakening of load-bearing wall is usually conducted based on field experience because reliable specifications or guidelines for the design of pre-weakening have not yet been established in Korea. This study is one of the efforts to develop such a reliable specification or guideline for the pre-weakening process. Hence, the focus of the study is on the estimation of pre-weakening range of load-bearing wall. For the purpose, a finite element analysis (FE analysis) was conducted, and a pre-weakening range of load-bearing wall was suggested based on the analysis result.

• Journal of Korean Society of Water and Wastewater
• /
• v.34 no.2
• /
• pp.149-159
• /
• 2020

Cured-in-place-pipe(CIPP) is the most adopted trenchless application for sewer rehabilitation to extend the life of the existing sewer without compromising both direct construction and indirect social costs especially applied in the congested urban area. This technology is globally and domestically known to be the most suitable for partial and full deteriorated pipe structure rehabilitation in a sewer system. The typical design of CIPP requires a significant thickness of lining to support loading causing sewage flow interruption and increasing material cost. This paper presents development of a high strength glass fiber composite lining material for the CIPP application and structural test results. The test results exhibit that the new glass fiber composite lining material has 12 times of flexural strength, 6.2 times of flexural modulus, and 0.5 Creep Retention Factor. These test results can reduce lining design thickness 35% at minimum. Even though taking into consideration extra materials such as outer and inner films for actual field applications, the structural capacity of the composite material significantly increases and it reduces 20 percent or more line thickness as compared to the conventional CIPP. We expect that the newly developed CIPP lining material lowers material costs and minimizes flow capacity reduction, and fully replaceable to the conventional CIPP lining materials.

• International Journal of Highway Engineering
• /
• v.20 no.3
• /
• pp.27-37
• /
• 2018

PURPOSES : The objective of this study is to develop a pavement rehabilitation decision tree considering current pavement condition by evaluating severity and distress types such as roughness, cracking and rutting. METHODS : To improve the proposed overall rehabilitation decision tree, current decision tree from Korea and decision trees from other countries were summarized and investigated. The problem when applying the current rehabilitation method obtained from the decision tree applied in Seoul was further analyzed. It was found that the current decision trees do not consider different distress characteristics such as crack type, road types and functions. Because of this, different distress values for IRI, crack rate and plastic deformation was added to the proposed decision tree to properly recommend appropriate pavement rehabilitation. Utilizing the 2017 Seoul pavement management system data and considering all factors as discussed, the proposed overall decision tree was revised and improved. RESULTS :In this study, the type of crack was included to the decision tree. Meanwhile current design thickness and special asphalt mixture were studied and improved to be applied on different pavement condition. In addition, the improved decision tree was incorporated with the Seoul asphalt overlay design program. In the case of Seoul's rehabilitation budget, rehabilitation budget can be optimized if a 25mm milling and overlay thickness is used. CONCLUSIONS:A practical and theoretical evaluation tool in pavement rehabilitation design was presented and proposed for Seoul City.

• International Journal of Highway Engineering
• /
• v.17 no.2
• /
• pp.89-98
• /
• 2015

PURPOSES : The objective of this study is to evaluate the performance properties of chip seals and fog seals with polymer-modified emulsions. METHODS : The performance of chip seals and fog seals was evaluated on the basis of common issues in surface treatments. Granite aggregate and four types of asphalt emulsions (one of the unmodified and three of the modified emulsions) were used considering the usage in field. A Vialit test was performed to determine the aggregate retention, and the MMLS3 (Third Scale Model Mobile Load Simulator) test was conducted to determine the aggregate retention, bleeding, and rutting. In addition, the fog seal specimens were tested by the BPT (British Pendulum Test) to evaluate skid resistance. RESULTS AND CONCLUSIONS : Overall, the polymer-modified emulsions (PMEs) showed better aggregate retention and bleeding resistance for both chip seals and fog seals. When comparing the performance of the PMEs, the difference was not considerable. In addition, PMEs present significantly better rutting resistance than unmodified emulsions. For skid resistance, if the recommended mix design is applied, the specimens do not cause issues with skid resistance. Although all of the fog seal specimens were over the criteria for skid resistance, the specimen fabricated by the high emulsion application rate (EAR) of the unmodified emulsion was nearly equivalent to the skid value criteria. Therefore, the use of an unmodified emulsion with a high EAR should be carefully applied in the field.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.757-760
• /
• 2008

The latex modified concrete was applied to baseplate of road bridge after 2000 year. This is in the limelight of stability to be missing problems. But, The baseplate of railroad bridge being experience to difficulty that searching method substituted for bridge waterproofing. In this study, I would like to application on P.C.L layer of railroad bridge using the property and merit of L.M.C. As a result performance test about six item, L.M.C was confirmed no problem to performance and application of bridge waterproofing.

• Korean Journal of Construction Engineering and Management
• /
• v.9 no.6
• /
• pp.204-215
• /
• 2008

Demolition work is a precedence activity that is performed earlier than other remodeling activities. And demolition work is one of the critical path activities. So, demolition work is needed for systematic plan and management. However, contractors of the remodeling project established a rough plan and did not consider recycling wastes, safety of workers and structural stable of building. To improve this problem, a eco-friend process model of remodeling project is needed to be established. The process model is composed of five phases; 1) survey and analysis of general condition of demolition work, 2) prepare documents of demolition work 3) establishing demolition work plan, 4) demolition and inspection, 5) post-demolition management. Especially, demolition documents are based on establishing WBS, selecting the equipment and method, waste management and structure reinforcement. A process model of eco-friend demolition work is developed by using IDEF0 method.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• 2004.11a
• /
• pp.561-564
• /
• 2004

Crack sealing automation machines' have been continually developed since the early 1990's because of the effectiveness of crack sealing that would be able to improve safety, quality and productivity. It has been considered challenging problem to detect crack network in pavement which includes noise (oil marks, skid marks, previously sealed cracks and inherent noise). It is required to develop crack network mapping and modeling algorithm in order to accurately inject sealant along to the middle of cut crack network. The primary objective of this study is to propose a crack network mapping and modeling algorithm using neural network for improving the accuracy of the algorithm used in the APCS. It is anticipated that the effective use of the proposed algorithms would be able to reduce error rate in image processing for detecting, mapping and modeling crack network as well as improving quality and productivity compared to existing vision algorithms.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.4
• /
• pp.1683-1691
• /
• 2013

Concrete surface grinding is frequently used for flatness of concrete surface, concrete pavement rehabilitation, and adhesiveness in pavement construction. The procedure is, however, labor intensive and has a hazardous work condition. Also, the productivity and the quality of concrete surface grinding highly depend on the skills of worker. Thus, the development of remote controlled concrete surface grinding equipment is necessary to prevent the environmental pollution and to protect the workers from hazardous work condition. However, it is difficult to evaluate the grinded surface objectively in a remote controlled system. Also, The machine vision system developed in this study takes the images of grinded surface with the network camera for image processing. Then, by representing the quality test results to the integrated program of the remote control station, the quality control system is constructed. The machine vision algorithm means the image processing algorithm of grinded concrete surface and this paper presents the objective quality control standard of grinded concrete surface through the application of the suggested algorithm.