• Journal of the Korea Concrete Institute
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• v.12 no.3
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• pp.39-46
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• 2000

This study is to investigate the watertightness properties of waterproofing admixture mixed redispersible polymer and siliceous powder. Series I deals with change in micro-structure of mortar by waterproofing admixture according to the water/cement ratios of 0.5, 0.6, 0.7 and 0.8 Crystal growth in micro-structure was observed through SEM to estimate on the watertightness effect of it. SeriesII deals with watertightness properties of waterproofing admixture on water permeability coefficient, crack restoration capacity and carbonation depth. SeriesII deals with watertightness properties of waterproofing admixture on water permeability coefficient, crack restoration capacity and carbonation depth. The result of this study can be summarized as follows. 1) Fluidity of mortar and concrete was increased by adding waterproofing admixture. 2) From observation through SEM. Crystals grew larger and denser in micro-structure as fiberic crystalization. 3) Waterproofing admixture is good watertightness properties in a level of high water/cement ratios and long limit of time. 4) Crack restoration capacity was appeared and durability was progressed by waterproofing admixture.

• Korean Journal of Agricultural Science
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• v.33 no.2
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• pp.167-177
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• 2006

This study was performed to evaluate void ratio, compressive and flexural strength, and pH properties according to the admixture ratio of rice husk ash, aggregate size, and neutral treatment time of porous concrete with an admixture of rice husk ash produced as an agricultural by-product. The SEM results for cement mortar with a 5% rice husk ash admixture for the weight of cement formed more C-S-H hydrates due to the $SiO_2$ present in the applied rice husk ash. According to the results of the SEM test, the $SiO_2$ that was a major chemical element of rice husk ash generated a large amount of calcium hydroxide in the early stage of the hydration process of cement leading to the formation of ettringite. The void ratio of porous concrete with an admixture of rice husk ash decreased with increasing admixture ratio of rice husk ash. In addition, the void ratio of porous concrete with an admixture of rice husk ash decreased compared to porous concrete with no admixture of rice husk ash. The compressive and flexural strength of porous concrete with a 5% and 10% admixture ratio of rice husk ash slightly increased compared to concrete with no admixture of rice husk ash. The pH value of porous concrete rapidly decreased immediately after neutral treatment. Then, it gradually increased and decreased again after 14 days. Also, for neutral treatment, the pH value of porous concrete showed appropriate pH levels(less than 9.5) in all mixtures for planting at 28 curing days.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.1
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• pp.55-62
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• 2003

This study has investigated physical and chemical properties of FRP waste, has manufactured polymer cement mortar using a crushed waste with sand and has evaluated its capability to develop the economical waste recycling technology. The study has investigated tension strength, hardness test and impact test as physical properties and also thermogravimetric characteristics and analyzed infrared spectroscope as chemical properties. Then the study has manufactured polymer cement mortar and has analyzed how the FRP waste fine aggregate replacement ratio has an effect on compression strength. Noticing admixture can complement strength drop occurred by the FRP waste fine aggregate replacement, the study examined an optimum rate of admixture addition and its reaction through electron microscope photos.

• Journal of the Korean Ceramic Society
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• v.44 no.1 s.296
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• pp.23-31
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• 2007

To examine the effects of chemical admixture on the fluidity and strength development of high chloride cement, experiments were conducted in which lignosulfonate (LS), naphthalenesulfonate (NS), and polycorboxylate (PC) were each added in standard and excessive amounts, and the results were as follows. 1. Because adding KCl to NS causes a decrease in flow, adding PC is better in maintaining high cement fluidity. 2. When cement contained much chloride comes in contact with water, hydration begins 4 h after contact and securing workability becomes difficult, but by adding PC, workability can be secured to 10 h. 3. The bound water ratio and compressive strength in aging 3 days occupy $70\sim80%$ of those in aging 28 days, and the early compressive strength increases not only by adding KCl, but also by chemical admixture. 4. Although compressive strength development is excellent in NS, PC, if NS is added excessively, hydration becomes slow and while the pore structures become slightly minute, the strength development decreases due to severe setting retardation.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.108-113
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• 1999

In structures, it is important to improve the capacity of waterproof in aspect of the durability and management of maintenance. Among the method of waterproof, self waterproof method is to improve the capacity of waterproof of structure itself. Thereby, we can expect the effect of durability and economics. In this study, we investigated the adding effect of waterproof admixture according to the water-cement ratio when used powder self waterproof admixture and analyzed the change of microstructure. Also, we were made to clear the mechanism of self waterproof admixture and intended to suggest the basic data on developing self waterproof admixture.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.557-560
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• 2003

This study deals with the method of test for waterproof agent and admixture of cement, and especially, the effect on bond strength between waterproofing layer and mortar or concrete substrate in building construction. Quality of that has been managed according to it of construction standard manual, housing construction manual, 건, and Q until performance of that is specified by law as KS F 4923. Therefore this study focus on the quality and trend for a fatty system and PCM(Polymer Cement Mortar)

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.89-94
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• 2003

Recently, the study to reduce and recycle industrial waste is underway vigorously in the various fields of industry according to the conservation of environment and resources. In construction work, the disposal problem of its waste and environmental disruption have already been serious all over the world. However the recycle of waste concrete is still at an early stage, recycled aggregate from waste concrete have only used those as subsidiary road fillers. The research institute and the company make the study that it is about the properties of recycled aggregate and those structural capacity since 1990. Through the experimentation last year, we know that strength and fluidity of recycle cement are inferior to normal cement, and admixing aggregate powder deteriorates its strength. The purpose of this study is to search for appropriate heating time and to improve performance of the recycle cement while heating hardened cement which is crushed, we investigate separating aggregate from hardened cement by preheating and improvement of strength and fluidity inrecycle cement which contains admixture.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.174-175
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• 2022

The blast furnace slag, which is widely used as a cement admixture, has latent hydraulics under the influence of cement hydrate, and fly ash and silica fume mainly cause a pozolane reaction. As a result, the cement structure becomes dense, and it is possible to compensate for defects when concrete is usually made with portland cement alone. When fixing carbon dioxide through reaction with carbon dioxide, the amount of calcium hydroxide in the cement paste is important. The larger the amount of calcium hydroxide, the more active the reaction may occur. It is also an important variable in calculating the depth of neutralization through carbonization. In this study, calcium hydroxide in cement paste using mixed materials was quantified through thermal analysis.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.5 no.6
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• pp.9-13
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• 2002

This study has been performed to investigate the physical and mechanical characteristics of compaction, volume change and compressive strength for reinforced soil mixed with cement. And confirm the reinforcing effects with admixture such as cement. To this end, a series of compaction test and compression test was conducted for clayey soil(CL) and cement reinforced soil. In order to determine proper moisture content and mixing ratio, pilot test was carried out for soil and cement reinforced soil. And the mixing ratio of cement admixture was fixed 3%, 6%, 9% and 12% by the weight of dry soil. As the experimental results, the maximum dry unit weight(${\gamma}_{dmax}$) was increased with the mixing ratio and then shown the peak at 10% reinforced soil, but the optimum moisture content(OMC) and the volume change was decreased with the ratio increase. And the compressive strength volume change was decreased with mixing ratio increased.

• Journal of the Korean Ceramic Society
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• v.27 no.4
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• pp.495-500
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• 1990

Investigation for the preparation of high strength hardened cement paste using ordinary portland cement, hydroxypropyl methyl cellulose (HPMC) with admixtures was carried out. For molding of the specimen, the paste was mixed with 0.1 of water cement ratio by twin roll mill. The maximum flexural strength of dried hardened cement paste was about 600∼700kg/㎠. When the SiC was added to the paste, the dry flexural strength was about 920kg/㎠ and the young's modulus was 5.2×105kg/㎠. When the admixtures were added to the specimens, wet strength of the harened cement paste immersed in water was showed around 50∼100kg/㎠ higher than that of plain specimen. Consequently it is recognized the water stability of hardened cement paste was remarkably improved by adequate admixture.