• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.225-226
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• 2016

Bottom ash generated in thermoelectric power plants could be used as substitutional fine aggregate such as pearlite of fireproof mortar due to its lightweight and porosity. Development of substitutional materials is necessary because pearlite has several problems such as production of carbon dioxide during manufacturing process and high price. This study is to confirm the possibility of air cooling process bottom ash for fireproof mortar as substitutional material of pearlite through basic experiment.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.2
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• pp.81-88
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• 2011

This study ascertained the possibility of use of sulfur abstracted from waste sulfur as a construction material through modification process and manufacturing high efficiency modification sulfur with superior quality on dispersibility and hydrophilic in normal temperature. Mechanic, behavior and chemical durability of mortar with added modification sulfur. The results of the study are as follows. The fluidity of mortar mixed with modification sulfur and compressive strength decreased as ratio of mixing of them increases. Flexural, tensile and bond strength of the mortar are also improved and shrinkage of it increases. Especially chemical durability of the mortar showed excellent resistance with the increase of ratio of mixing. Therefore this research has confirmed the modification sulfur can be used as a addmixture for cement.

• Journal of the Korea Institute of Building Construction
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• v.20 no.4
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• pp.305-311
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• 2020

Polymer modified cement mortar (PCM) can improve the performance of adhesion strength, flexural strength, chemical resistance, etc., compared with cement mortar, and is widely used when repairing RC structures. However, PCM causes a burst in an environment with high temperature and fire rate, which causes problems in the stability of the structure. In this study, for the purpose of developing explosive reduction PCM, the polymer mixing ratio is 2%, 4%, 6%, the fiber length is 6mm, 12mm, 6+12mm, and the PP fiber mixing rate is 0.05 Vol% and 0.1 Vol%. Furnace heating experiment (600℃, 800℃) was carried out. As a result of comparative analysis of the explosive properties, it was confirmed that the explosive reduction effect due to the fiber incorporation was insufficient when the polymer mixing amount was 6% or more.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.365-372
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• 2018

3D printing technology of construction field can be divided into structural materials, interior and exterior finishing materials, and is mainly done by extruding and adapting. Particularly when it is applied as an exterior materials, it is mainly applied to an unstructured exterior materials and high accuracy is required. The exterior materials can be used as a cement composite materials, it is suitable also for a additive type manufacturing, and the role of a redispersible polymer powder is important. But, high temperatures, redispersible polymer cement base material beget dehydration and micro crack of cement matrix. In this research, we developed a EVA, EVCL redispersible polymer cement base material applicable as a 3D printing exterior materials, confirmed density and strength characteristics for application as an exterior materials, a flame retardancy test for improving the fire resistance of buildings and confirmed its possibility. From the test result, developed EVCL redispersible polymer cement mortar showed good stability in high temperatures. These high temperature stability is caused by the ethylene-vinyl chloride binding. Thus, this result indicates that it is possible to fire resistant 3D printing interior and exterior finishing materials.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.6
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• pp.429-441
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• 2010

In this study, fire resistance of a fireproof material sprayed upon an immersed tunnel was experimentally evaluated under $HC_{inc}$ and IS0834(duration of 4 hours) fire scenarios. Under $HC_{inc}$ fire scenario, the maximum inner temperatures of a concrete specimen at the depth of 0, 25 and 50 mm from the interface between the structure and the fire-proofing layer were $311^{\circ}C$, $194^{\circ}C$ and $142^{\circ}C$ respectively. Similarly, the corresponding maximum temperatures under IS0834 fire scenario were $332^{\circ}C$, $222^{\circ}C$ and $179^{\circ}C$ respectively. From the results, it was revealed that the two different fire scenarios assumed in this study have almost the same fire capacity as each other in the maximum temperature concept. In addition, a structural analysis of the immersed tunnel under $HC_{inc}$ fire scenario was carried out to verify the effects of the fireproof material on its structural stability. Material loss and deterioration of a concrete specimen without any fire-proofing measure was also experimentally evaluated to obtain input parameters for the structural analysis under such a severe fire scenario. From the results, it was confirmed that the application of fireproof measures to the immersed tunnel is essential for its structural stability even under a severe fire scenario.

• Journal of the Korea Institute of Building Construction
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• v.17 no.5
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• pp.411-418
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• 2017

This study classified oyster shells that produced as a industrial waste into 3 distribution by washing, drying and processing them. Mortar specimens with a constant ratio by using this to substitute fine aggregates were made, and the specimens were heated under the heating conditions of $300^{\circ}C$, $600^{\circ}C$ and $900^{\circ}C$ based on the 28-day age. On the age of 28 days, the plain flexural strength was found to be 9.2MPa, and in O 0.15, it was shown to be 4.4~7.9MPa depending on the substitution rate. It was found to be 4.4~7.7MPa in O 1.2~2.5 depending on the substitution rate, and last but not least, it was shown to be 6.1~8.8MPa in case of O 2.5~5.0 depending on the substitution rate. In case of the compressive strength of the 28-day age, it showed the difference of 23.6~43.2MPa in O 0.15 depending on the substitution rate, and 20.4~45.1MPa in O 1.2~2.5 depending on the substitution rate, and last but not least, 17.1~40.4MPa in case of O 2.5~5.0. As a result of measuring the residual strength through heating, in case of substituting fine aggregates less than O 0.15 by 100%, it showed the lowest strength reduction ratio, and it is expected that the heat-resisting property could be achieved through processing and proper mixing of oyster shells through these results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.3
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• pp.120-128
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• 2005

In the construction industry, due to the cost rise of raw material for concrete, we have looked into recycling by-products which came from foundry. When using the Ground Granulated Blast-Furnace Slag(SG), it is good for enhancing the qualities of concrete such as reducing hydration heat, increasing fluidity, long-term strength and durability, but it has some problems : construction time is increased or the rotation rate of form is decreased due to low development of early strength. In this study, therefore, to enhance the early strength of SG mortar, we used some alkali activators(KOH, NaOH, $Na_2CO_3$, $Na_2SO_4$, water glass, $Ca(OH)_2$, alum. This paper deals with reacted products, setting time, heat evolution rate, flow and the strength development of SG cement mortar activated by alkali activators. From the results, if alkali activators were selected and added properly, SG is good for using as the materials of mortar and concrete.

• Journal of the Korea Concrete Institute
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• v.15 no.4
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• pp.549-556
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• 2003

Various researches on the application of polymer dispersions to the cement mortar and concrete have been practised in many countries like America, Japan and Germany and so on because of high performance and good modification effect of these. In this study, SBR, Polymer dispersion that widely used in situ is employed that the self-flowability may be induced in the cemen mortar. In order to comprehend and investigate the modification of cement mortar with self-flowability by SBR and properties and fracture mode of adhesive strength in tension of that, experimental parameter was set as SBR solid-Cement ratio(S/C) and Cement:Fine aggregate(C:F) and the experiments such as Unit weight, Flow, Consistency change, Crack resistance and Segregation that inform on the general properties have been done. In addition of that, Adhesion in tension is measured with a view to comprehending the properties and fracture mode in tensile load. Consistency change of cement mortar modified by SBR did grow better as the ratio of SBR solid-Cement increased and was much superior to that of resin based flooring such as polyurethane and epoxy which recorded the loss of consistency in 90min. after mixing. Adhesive strength in tension increased with continuity in the curing age and showed the maximum in case of C:F=1:1 and S/C=20%. As the increase of curing age, the fracture mainly happened in the concrete substrate and the interface between the specimen and concrete substrate.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.204-210
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• 2022

Cement is pointed out as the main cause of carbon dioxide emission in the construction industry. Many researchs are underway to use blast furnace slag, an industrial by-product, as a substitute for cement to reduce carbon dioxide emitted during the manufacturing the cement. When blast furnace slag is used as a substitute for cement, it has advantages such as long-term strength and chemical resistance improvement. However, blast furnace slag has a problem that makes initial strength low. This is due to the impermeable film on the surface created during the production of blast furnace slag. The created film is known to be destroyed in an alkaline environment, and based on this, previous studies have suggested a solution using various alkali activators. But, alkali activator is dangerous product since it is a strong alkaline material. And it has the disadvantage in price competitiveness. In this study, an experiment was conducted to improve the initial hydration reactivity of the blast furnace slag to secure the initial strength of the mortar substituted with the blast furnace slag and to check whether the carbonation resistance was increased. As a result of the experiment, it was confirmed that the mortar using alkaline water showed higher strength than the mortar using tap water, and there were more hydration products generated inside. In addition, it was confirmed that the mortar using alkaline water as a compounding water had high carbonation resistance.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.607-610
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• 2005

If cement can be manufactured with industrial byproducts such as granulated blast furnace slag(GBFS), phosphogypsum(PG), and waste lime(WL) instead of clinker as its counterproposal, there would be many advantages, including maximum use of these industrial byproducts for high value-added resources, conservation of natural resources and energy by omitting the use of clinker, minimized environmental pollution problems caused by $CO_2$ discharge, and reduction of the production cost. This research investigates the chemical resistance of NSC mortar added PG and WL to GBFS as sulfate and alkali activators. The result of experiment of chemical resistance, showed that NSC is very excellent in acid resistance and seawater resistanc. Such a reasons are that the hydrate like CSH gel and ettringite formed dense pore structure of NSC matrix.