• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.89-92
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• 2008

This research analyzed the basic characteristics of unhardened concrete and the compression strength characteristics of hardened concrete according to liquidity retention agent mix rate change to improve the liquidity fluidity retention performance of high performance concrete, and produced the following results. The moment fluidity retention agent is added according to fluidity retention agent mix rate change, which increased fluidity retention agent mix rate, slump flow decreased, and in the case of slump flow according to the progress time change by the fluidity retention agent mix rates, the more fluidity retention agent mix rate increased, the lower slump flow change rate became. The moment fluidity retention agent is added according to fluidity retention agent mix rate change, fluidity retention agent mix rate increased compared to non-mixture of fluidity retention agent, and the air amount by progress time change by the fluidity retention agent mix rates slightly increased, however target range is still met and unit volume mass is inversely proportional to air amount. Compression strength according to age progress by the fluidity retention agent mix rates was shown to increase slightly with increase in fluidity retention agent mix rate, and yet the difference was not significant.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.201-202
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• 2019

The high performace water reducing agent with three-hours-fluidity-retention performance is developed for the purpose of entering into the global market belonging to extreme environment such as Southeast Asia and the Middle East. In this study, the fresh and mechanical properties of the high strength concrete with three-hours-fluidity-retention performance are evaluated by making mock-up members in Vietnam.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.128-129
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• 2018

The high performace water reducing agent with three-hours-fluidity-retention performance is developed for the purpose of entering into the global market belonging to extreme environment such as Southeast Asia and the Middle East. In this study, the fresh and mechanical properties of the concrete with three-hours-fluidity-retention performance are presented.

• Journal of the Korean Ceramic Society
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• v.34 no.12
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• pp.1261-1267
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• 1997

Four kids of powder admixtures(A, B, C, D) based on anhydrite were manufactured by mixing at a fixed rate of II-anhydrite, fly ash and active silica as an industrial by-product. Fluidity properties of cement paste such as mini-slump, apparent viscosity with elapsed time, as well as setting time of cement pastes of these admixtures substituted up to 11wt% of cement were compared to those of cement paste(SS) substisuted by marketed high-strength powder admixture(S). Among these powder admixtures, the fluidity of cement pastes(PA, PC) substituted by A and C powder admixtures manufactured from II-anhydrite and fly ash had an excellent property than that of cement paste substituted by marketed powder admixture and also a good fluidity-retention effect with elapsed time by adding of superplasticizer. The setting time of cement paste substituted by powder admixtures based on anhydrite slightly retarded than that of cement paste substituted by marketed powder admixture.

• Magazine of the Korea Concrete Institute
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• v.7 no.5
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• pp.189-199
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• 1995

Naphthalene sulfonated condensate has been widely used as a superplasticizer for cement and concrete, but the application was limited due to its large slump loss with elapsed time. To complement this demerit of NSF, polycarboxylic acid copolymer from nlaleic anhydride and acryl~c acid(MA) was synthesized to retain the mobility of cement and concrete, and then mixed with NSF. The physical properties, such as fluidity, fluidityretention and rheology, were measured by applying these admixtures to cement paste as a function of elapsed time. And also compressive strength of mortar was measured with curing time. NIv-l and NM-2 containing 10, 20 wt% of MA respectively had a excellent fluidity and a fluidity- retention. In rheological property, the increases of shear stress and viscosity with elapsed time were delayed with the increasing of shear rate in cornparision with NSF only. The marked slump loss of cement paste could be controlled by these admixture. Also the added ainount of admixture and the ratio of water to cement affected these properties.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.94-99
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• 1995

Naphthalene sulfonated condensatd(NSF) has been widely using for the superplasticizing of ement and concrete. But NSF has a very large mobility loss with elapsed tiom. To retain mobility of NSF during a certain time, maleic anhydride and acrylic acid copolymer(MA) was polymerized and mixed with NSF in order to perpare admixture holding mobility-retention property of cement. By applying this admixture for ement paste, we examined the fluidity and mobility retention property as a function to elapsed time and measured the compressive strength of mortar with curing time. As a result, NSF containing 20wt% of MA showed very excellent fluidity and mobility-retention property. These properties were affected by the added amount of admixture and the ratio of water to cement.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.271-276
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• 2003

This study is about the rheological properties of cement slurry using admixtures. The variables are the type of cement(Type I, II, IV, V) and the substitution ratio of admixtures such as fly ash and slag. As a result of measuring the fluidity of various types of cement slurry at the early stage, type 2, type 4 and type 5 showed the similar property. The fluidity of type 1 and ternary blended cement was low. it is thought that it is because of the high $C_3$A content. The cement slurries containing mineral admixtures were superior in the property of fluidity retention.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.89-94
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• 1999

The workability of high strength concrete using high range water reducing admixture is varied rapidly according to elapsed time. For using the high strength concrete in situ, careful caution on workability is necessary. By using fly ash as a admixture, the slump loss of concrete can be reduced considerably, but the early strength of concrete used fly ash is smaller than that not used fly ash. For the purpose of elevating the utilization of fly ash on high strength concrete, the high fluidity retention and the strength development in early age are necessary in concrete used fly ash. In this study, to improve the fluidity retention and to acquire strength development on concrete used fly ash, the gypsum is applied.

• Advances in concrete construction
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• v.6 no.6
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• pp.561-583
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• 2018

A variety of polycarboxylate ether (PCE)-based superplasticizers are commercially available. Their influence on the rheological retention and slump loss in respect of concrete differ considerably. Fluidity and slump loss are the cardinal features responsible for the quality of concrete. These are related to the dispersion of cement particles and the hydration process which are greatly influenced by type of polycarboxylate ether (PCE)-based superplasticizers. On the backdrop of relatively less studies in the context of rheological retention of high strength self-consolidating concrete (HS-SCC), the experimental investigations were carried out aiming at quantifying the effect of the six different PCE polymers (PCE 1-6) on the rheological retention of HS-SCC mixes containing two types of Ordinary Portland Cements (OPC) and unwashed crushed sand as the fine aggregate. The tests that were carried out included $T_{500}$, V-Funnel, yield stress and viscosity retention tests. The supplementary cementitious materials such as fly ash (FA) and micro-silica (MS) were also used in ternary blend keeping the mix paste volume and flow of concrete constant. Low water to binder ratio was used. The results reveal that not only the PCEs of different polymer groups behave differently, but even the PCEs of same polymer groups also behave differently. The study also indicates that the HS-SCC mixes containing PCE 6 and PCE 5 performed better as compared to the mixes containing PCE 1, PCE 2, PCE 3 and PCE 4 in respect of all the rheological tests. The PCE 6 is a new class of chemical admixtures known as Polyaryl Ether (PAE) developed by BASF to provide better rheological properties in even in HS-SCC mixes at low water to binder mix. In the present study, the PCE 6, is found to help not only in reduction in the plastic viscosity and yield stress, but also provide good rheological retention over the period of 180 minutes. Further, the early compressive strength properties (one day compressive strength) highly depend on the type of PCE polymer. The side chain length of PCE polymer and the fineness of the cement considerably affect the early strength gain.

• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.486-490
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• 1999

In this study, to improve the required properties of tile cement mortar such as excellent water retention capacity (WRC), workability, open time, sag resistance, and tile adhesive strength, tile cement mortars containing the several additives with different ratio were compared and analyzed. By adding small amount of synthesized starch to hydroxypropyl methylcellulose (HPMC) which is used for improving WRC, the decrease of moisture evacuation from mortar surface was observed and the workability of mortar was improved with long open time. Polyacrylamide (PAAm) and ethylencvinyl acetate (EVAc) were also added in order to increase the adhesion of tile. As a results, the saggings of mortar itself and tile were decreased and the adhesive strength of mortar between base and tile was enhanced. By adding melment, the workability was improved by increasing the fluidity of mortar. It is postulated that the properties of tile cement mortar was improved by adding 0.80~1.20% of HPMC, 0.10~0.15% of starch, 0.001~0.015% of PAAm, 0.05~0.10% of EVAc and 0.003~0.005% of melment to the cement mortar.