• Journal of the Korean Recycled Construction Resources Institute
• /
• v.9 no.1
• /
• pp.33-40
• /
• 2021

The objective of this work is to prove a possibility of void f illing through a carbonation f or the purpose of improving the quality of recycled aggregate. Carbonation can permanently immobilize CO2, which is a greenhouse gas, and thus provides additional benefit on environment. In this work, recycled fine aggregate was reacted using gaseous CO2 and supercritical CO2(scCO2) in a closed chamber, and the changes in physical properties of the recycled f ine aggregate bef ore and af ter carbonation were analyzed using the apparent density, skeletal density, pH, and FE-SEM measurements. Thereafter, a mortar specimen was prepared and a compressive strength was measured. According to the experimental results, it was found that the increase in the apparent density and the true density was higher by the reaction with scCO2, which was conducted at high temperature and high pressure compared to the reaction with gaseous CO2. In addition, the pH of the eluted water was found to have a larger initial decrease than that observed with samples from reaction by gaseous CO2. The shape and amount of calcium carbonate crystals were also found to be larger than that from gaseous CO2. The increase in compressive strength was the largest when using recycled fine aggregate reacted with scCO2. It was clear that quality improvement of recycled fine aggregate was higher with scCO2 than with gaseous CO2.

• Journal of the Korea Institute of Building Construction
• /
• v.22 no.6
• /
• pp.663-672
• /
• 2022

The purpose of this study is to evaluate the magnesium sulfate resistance of a geopolymer mixed with rice husk powder. General concrete, silica fume mixed concrete, and binary blended geopolymer were selected as comparison targets to confirm the magnesium sulfate resistance, and sulfate deterioration was calculated using the compressive strengths with ages. In addition, the weight change rate and the relative dynamic coefficient of the geopolymer were comparatively analyzed, and the degree of etteringite formation was confirmed using X-ray diffraction analysis. the experiment, the geopolymer mixed with 10% rice husk powder showed 10.8% higher compressive strength than concrete with silica fume when submerged for 56 days. Also, the geopolymer mixed with rice husk powder showed a small weight change rate of 0.9 to 1.45%. composition after immersion in magnesium sulfate through X-ray diffraction analysis, it was observed that a small amount of ettringite was dispersed in the geopolymer containing rice husk powder. Thus, there is a high correlation with the corrosion resistance of magnesium sulfate

• Journal of the Korea Institute of Building Construction
• /
• v.22 no.1
• /
• pp.23-34
• /
• 2022

The purpose of this study is to evaluate the adhesion properties of polymer cement composites for crack repair of an RC structure. Polymer cement composites are manufactured from cement, three types of polymers and silica fume, and the mixture is designed by adjusting the water cement ratio and AE reducing agent so that the viscosity target of the polymer cement composites is 700mPa·s or less. According to the test results, the Type-A adhesion in tension of the polymer cement composite exceeded the adhesion standard of 1.0MPa of the polymer finishing material, and furthermore, depending on the type of polymer, the adhesion in tension was highest for SAE, followed in descending order by EVA, and SBR. In addition, the adhesion in tension of Type-B is up to 1/4.5 lower than that of Type-A, but the incorporation of silica fume shows a significant improvement in terms of adhesion in tension. Based on this study, the basic mixing design of the polymer cement composites required for viscosity and adhesive performance required for crack repair of the RC structure was completed. It could be proposed as an optimal mixing design under conditions for intermixing polymer type EVA, SAE, and P/C 80%-100%.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.6D
• /
• pp.849-857
• /
• 2008

Technology roadmapping is one of the widely used technology planning methodologies. Using a technology roadmap, the researchers can increase the possibility of the project success by systematic management of research contents, budgets, and commercialization strategies. Currently, Ministry of Land, Transport and Maritime Affairs has a plan to increase the research fund to improve the construction industry. As a result, the number of long term research projects with more than five years of research period, is increasing. This entails the need for a methodology for the systematic planning and management of research. However, the construction industry has the characteristics that the research results should ultimately be implemented in an outdoor environment. Through processes of diverse literature reviews, questionnaire-based survey, and pilot research, this paper presents a systematic procedure for the development of construction technology roadmaps, which can consider the unique nature of the construction industry. Based on the procedure, a technology roadmap for intelligent construction monitoring is also developed.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.10 no.6 s.52
• /
• pp.93-102
• /
• 2006

Control input's saturation of active control devices for large structures under large external disturbances are often occurred. It is more difficult to obtain the exact values of mass and stiffness as structures are higher. The modelling errors between mathematical models and real structures must be also included as parameter uncertainties. Therefore, in active vibration control of civil engineering structures like buildings and bridges, the robust saturation controller design method considering both control input's saturation and parameter uncertainties of system is needed. In this paper, stabilities of linear optimal controller LQR, modified bang-bang controller, saturated sliding mode controller, and robust saturation controller among various controllers which have been studied and applied to active vibration control of buildings are investigated. Especially, unstable phenomena of the LQR, the modified bang-bang controller and the saturated sliding mode controller when the control input is saturated or parameter uncertainties exist are presented to show the necessity of the robust saturation controller. The robust stability of the robust saturation controller are shown through a numerical example of a 2DOF linear vibrating system and an experimental test of the two-story structure with an active mass damper (AMD).

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.21 no.6
• /
• pp.266-273
• /
• 2011

Foamed glass was fabricated by using glass powder and foaming agents. For the glass powder, we used sodalime glass which's manufactured by using refused coal ore obtained as by-product from Dogye coal mine in Samcheok. And for the foaming agents, we used Calcium carbonate, Calcium phosphate and powder of shale type refused coal ore itself which has high content of carbon materials. We additionally used liquid binder for forming, and mixed together. And we formed rectangular shape and treated $800^{\circ}C$ for 20 min in an electrical furnace. The various kinds of foam glass samples were fabricated according to the kinds of foaming agents. The physical properties of samples, as specific gravity and compressive strength, were measured. Pore structure of each samples were investigated too. Foam glass with specific gravity of 0.4~0.7 and compressive strength of 30~72 kg/$cm^2$. Especially we get satisfying foam glass sample with low specific gravity of 0.47 and high compressive strength of 72 kg/$cm^2$ by the use of liquid calcium phosphate as foaming agent. It also had small and even shape of pore structure. Therefore, it is concluded that refused coal ore can be used for raw materials to manufacture secondary glass products such as a foamed glass panel for construction and industrial materials.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.17 no.3
• /
• pp.93-103
• /
• 2014

Regarding to the cadastral information and building information as a spatial information, studies on linking between cadastral records and building information, or integration methodology on 2D based building map and land information were proposed. Cadastral information has grown its values by cadastral resurvey project and cadastral confirmation survey. There is a tendency of BIM in the design stage which is not just simple 3D dataset and BIM is spreading in public and private sectors. However, studies on the linkage between building information and cadastral information is relatively weak comparing to the BIM spreading. One of the main features that have been improved in IFC4 is the interoperability with GIS. In this regards, the researcher propose several revision methods to link cadastral information to building information. Cadastral information needs to improve the quality of the dataset's such as unifying the different coordinate systems and preparing continuous cadastral map. For buildings, standardization of BIM in the public and private sectors is urgent task. IFC4 and upcoming IFC5 are international standards which need to be considered and BIM reverse engineering for the existing buildings is necessary for the public utilization in the near future.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.20 no.1
• /
• pp.43-52
• /
• 2010

Glass was fabricated by using refused coal ore obtained from Dogye coal mine in Samchuk. We additionally used soda ash and calcium carbonate as raw materials to make a glass with the chemical composition of soda-lime glass. And the properties of glass were measured when limestone was used as natural raw materials instead of calcium carbonate as chemical raw materials. Transparent glass was fabricated by melting raw materials at $1550^{\circ}C$ for 1 hr in an electrical furnace. The various kinds of glass samples were fabricated according to the kinds of refused coal ore and glass cullet. The optical properties of transmittance and color chromaticity were measured by UV/VIS/NIR spectrometer and the thermal properties of thermal expansion coefficient and softening point were measured. Transparent glass with the transmittance of over 70% in visible range was fabricated by using normal refused coal ore and black colored glass with the transmittance of 0~35% was fabricated by using shel1 type refused coal ore. Therefore, it is concluded that refused coal ore can be used for raw materials to manufacture secondary glass products such as a glass tile and foamed glass panel for construction material.

• Land and Housing Review
• /
• v.4 no.3
• /
• pp.279-286
• /
• 2013

Driving a prefabricated pile is the efficient construction method with low cost and excellent bearing capacity charateristics. But pile drinving method has often been changed to bored pile method with mechanical boring due to the unexpected problems occurred in the various domestic ground condition with landfill. So, pile driving method has more uncertainty than the Bored Pile method. This paper proposed LRFD design value which is one of limit states design method for the PHC driven pile used as building foundation to guarantee the reliable design with reduced uncertainty. This paper analysed 221 dynamic load test results(E.O.I.D : 93, Resrike : 128) and the different methods of estimating bearing design(Meyerhof method & SPT-CPT conversion method), and proposed LRFD value for each design reliability Index 2.33 and 3.0 for PHC driven pile. LRFD value of PHC driven pile represents 0.43~0.55 for Meyerhof method and 0.40~0.49 for SPT-CPT conversion method according to the deign reliability index.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.7 no.1
• /
• pp.22-28
• /
• 2019

Cement is a basic material for the construction industry and it requires high temperature sintering when manufacturing cement. $CO_2$ emissions from raw materials and fuels are recognized as new environmental problems and efforts are underway to reduce them. Techniques for reducing $CO_2$ in concrete are also recommended to use blended cement such as blast furnace slag or fly ash. In addition, the construction waste generated in the dismantling of concrete structures is recognized as another environmental problem. Thus, various methods are being implemented to increase the recycling rate. The purpose of this study is to utilize the inorganic raw materials generated during the dismantling of the structure as a raw material for the low carbon type cement binder. Such as, waste concrete powder, waste cement block, waste clay brick and waste textile as raw materials for low carbon type cement binder. From the research results, low carbon type cement binder was manufactured from the raw material composition of waste concrete powder, waste cement block, waste clay brick and waste textile.