• International Journal of Concrete Structures and Materials
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• v.11 no.1
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• pp.99-113
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• 2017

The effects of different lightweight functional fillers on the properties of cement-based composites are investigated in this study. The fillers include fly ash cenospheres (FACs) and glass micro-spheres (GMS15 and GMS38) in various proportions. The developed composites were tested for compressive, flexural and tensile strengths at 10 and 28-day ages. The results indicated that both FACs and GMS38 are excellent candidates for producing strong lightweight composites. However, incorporation of GMS15 resulted in much lower specific strength values (only up to $13.64kPa/kg\;m^3$) due to its thinner shell thickness and lower isostatic crushing strength value (2.07 MPa). Microstructural analyses further revealed that GMS38 and GMS15 were better suited for thermal insulating applications. However, higher weight fraction of the fillers in composites leads to increased porosity which might be detrimental to their strength development.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.6
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• pp.315-325
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• 2017

This study aims to provide information for the design and use of structural lightweight concrete (SLWC) for floating concrete structures in a marine environment. An experimental program was set up and comprehensive experimental campaign were carried out to determine SLWC mix proportions that can satisfy specified concrete strength, density, and slump values all of them were determined from previous research. Comparisons with previous SLWC mix designs that have been utilized for actual floating concrete structures were made. Key aspects needed to be considered regarding to the use of SLWC for floating marine concrete structures were discussed.

• Journal of the Korea Institute of Building Construction
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• v.14 no.4
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• pp.301-307
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• 2014

In order to reduce the emission of carbon dioxide($CO_2$), this research use blast furnace slag in concrete manufacture, as 100% replacement of cement. The aim of this study is to investigate the density and strength properties of alkali-activated lightweight composites with alkali activators of different types and different amounts. The bubble for achieving the lightweight of alkali-activated lightweight composites was generated in the reaction between the paper ash and the alkali activators instead of using a foaming agent. Lightweight formed concrete was conducted basic experimental for determining replacement ratio of paper ash. Then, the density and strength were measured according to the types and the contents of the alkali accelerator that can react with the paper ash. As results, the optimum replacement ratio of the paper ash was 5%. The alkali activator containing NaOH 12.5% obtained the lowest weight of $1.13g/cm^3$. Also, compressive strength were relatively high. Therefore, this study demonstrated that alkali accelerator with a certain amount of NaOH can achieve relatively high strength and lightweight alkali-activated lightweight composites.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.54-59
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• 2020

Coarse aggregate is produced in various ways depending on the location and production method. Currently, the construction industry is in need of a stable supply of coarse aggregate and a way to secure standard quality. The purpose of this study is to examine whether the use of coarse aggregate in 3D printing can help solve this problem. ABS filament was selected for use in 3D printing. CATIA was used for the design of the coarse aggregate, and CUBICON Single Plus was used for the production. Six specimens were produced and cured in water for 28 days. Three of them were made with AE agent, and three were made without it. A compressive strength test confirmed that when the AE agent was used, the compressive strength was greater than the lightweight concrete design criterion specified in the concrete standard specification. This suggests that coarse aggregate produced by a 3D printer may be used for lightweight concrete. A mass production system using this method could help to solve the problems facing the construction industry, such as stable supply and demand for coarse aggregate and securing standard quality.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.3
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• pp.27-36
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• 2024

This study established a BIM procedure considering manufacturing errors in the production process, and evaluated the flexural ductility of precast all-lightweight aggregate concrete special shear walls (PLASWs) with spliced sleeve technique. In the production process, the concrete cover thickness of PALSW was on average 1.28 times greater than the cross-sectional details of the specimen modeled with Revit BIM program. In particular, the bending inner radius of the hoop and inner-cross tie were greater than the designed details. Consequently, the confinement effect of core concrete reduced from 64% to 54% due to the manufacturing errors in the transverse reinforcing bars, resulting in a decrease in the ductility of PALSW by approximately 4.91%. Considering these findings, the BIM of PLASW with spliced sleeve technique should compliment the bending inner radius of the transverse reinforcing bars, and the defined brittleness increase coefficient reflecting the decreased core concrete confining pressure in the stress-strain relationship of confined concrete should be evaluated as 1.8.

• Computers and Concrete
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• v.19 no.2
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• pp.217-226
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• 2017

This paper summarizes the results of experimental research, and artificial intelligence methods focused on determination of compressive strength of lightweight cement mortar with silica fume and fly ash after sulfate attack. The artificial neural network and the support vector machine were selected as artificial intelligence methods. Lightweight cement mortar mixtures containing silica fume and fly ash were prepared in this study. After specimens were cured in $20{\pm}2^{\circ}C$ waters for 28 days, the specimens were cured in different sulfate concentrations (0%, 1% $MgSO_4^{-2}$, 2% $MgSO_4^{-2}$, and 4% $MgSO_4^{-2}$ for 28, 60, 90, 120, 150, 180, 210 and 365 days. At the end of these curing periods, the compressive strengths of lightweight cement mortars were tested. The input variables for the artificial neural network and the support vector machine were selected as the amount of cement, the amount of fly ash, the amount of silica fumes, the amount of aggregates, the sulfate percentage, and the curing time. The compressive strength of the lightweight cement mortar was the output variable. The model results were compared with the experimental results. The best prediction results were obtained from the artificial neural network model with the Powell-Beale conjugate gradient backpropagation training algorithm.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.10-11
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• 2019

The purpose of this study is to validate the environmental performance of the 'eco-friendly lightweight form' in the construction process. Unlike existing euro form and aluminum form, the proposed form does not require form oil during the process of concrete casting and is lightweight because it is made of engineering plastic. Therefore, eco-friendly lightweight form will reduce the $CO_2$ emissions in the construction process. To verify the hypothesis, the study compared existing forms and eco-friendly light weight form's $CO_2$ emissions in each stage in construction process when using 1,000 forms and 100 times from the LCI(Life Cycle Inventory) data. The total $CO_2$ emissions of the eco-friendly light weight form were 30,487kg $CO_2$, which equated to about 58% and 20% less emissions than the euroform and aluminum form. The result of the study verified that the eco-friendly lightweight form was effectively reduced $CO_2$ emission in the construction process.

• Proceedings of the Korea Concrete Institute Conference
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• 1990.04a
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• pp.11-15
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• 1990

Results of an experimental study on the manufacture and the mechanical properties of carbon fiber reinforced fly ash-cement composites are presented in this paper. The carbon fiber reinforced fly ash-cement composites using silica powder and a small amount of Ethylene vinyl acetate emulsion are prepared with carbon fiber, foaming agents and curing conditions. As a result, the manufacturing process technology of carbon fiber reinforced fly ash-cement composites is developed. And the mechanical properties such as compressive, tensile and flexural strengths and drying shrinkage of lightweight carbon fiber reinforced fly ash-cement composites are improved by using a small amount of Ethylene vinyle acetate emulsion. The development and applications of precast products and the design systems of lightweight carbon fiber reinforced fly ash-cement composites are expected in the near future.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.757-760
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• 2005

In this study, glass abrasive sludge was utilized for a light weight material and graphite was used as expanding agent. The glass abrasive sludge with added expanding agent was formed into pellet by a pelletizer. When glass abrasive sludge is made as pellet, water glass is added as a binder(water : water glass = 8 : 2). The pellet was sintered at $700\~800^{\circ}C$ by rotary kiln composed of 4 segment temp. system. The absorption ratio of lightweight materials tended to increase in proportion to increasing content of graphite. The lowest value of specific gravity that was observed in this study was $1.8\%$.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.594-599
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• 2000

Two basic acoustic quantities, the characteristic impedances and the propagation constants, of the two different ultra lightweight concrete absorbers were examined with impedance tube method. A transmission loss was tested and compared with theoretical values. The results show that these kinds of sample have proper sound absorption and transmission loss capabilities. It means that they can be used in various fields where noise proof is needed.