• Journal of the Korea Concrete Institute
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• v.17 no.5 s.89
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• pp.703-708
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• 2005

The effects of polymer-cement ratio and antifoamer content on the setting time and durability of high-fluidity polymer-modified mortars using redispersible polymer powder are examined. As the result, the setting time of the polymer-modified mortars using redispersible polymer powder tends to be delayed with increasing polymer-cement ratio, regardless of the antifoamer content. The water absorption, chloride ion penetration depth and carbonation depth of the high-fluidity polymer-modified mortars using redispersible polymer powder decrease with increasing polymer-cement ratio and antifoamer content. The resistance of freezing and thawing and chemicals improvement is attributed to the improved bond between cement hydrates and aggregates because of the incorporation of redispersible polymer powder

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.3
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• pp.118-125
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• 2011

The size and distribution of concrete void was one among the factor determining durability of concrete. Recently, there was a lot of researches related to the High-Fludity Concrete(HFC) with field applications. However, the research about the void structure having an effect on durability of concrete is insufficient. Therefore, in this research, Conventional Concrete(CC) and HFC using lime stone powder and fly-ash of 30 MPa range was manufactured and observed the void structure of CC and HFC. Experimental results showed that average pore diameter in the case of the 30 MPa range HFC was to be lower than CC and SEM analyzed result, HFC was firmer inner structure than CC.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.925-928
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• 2006

The effects of polymer-binder ratio, antifoamer content and shrinkage-reducing agent content on the air content and strengths of high-fluidity polymer-modified pastes are examined. As a result, the air content of the polymer-modified pastes tends to decrease with increasing polymer-binder ratio and antifoamer content. Irrespective of the antifoamer content, the flexural and tensile strengths of the high-fluidity polymer-modified pastes tends to increase with increasing polymer-binder ratio, and tend to decrease with increasing shrinkage-reducing agent content. However, the compressive strength of the polymer-modified pastes decreases with increasing polymer-binder ratio and shrinkage-reducing agent content.

• Journal of the Korea Institute of Building Construction
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• v.20 no.5
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• pp.399-407
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• 2020

The aim of the research is to provide the boundary conditions for segregation of normal strength grade and high fluidity concrete mixture (so called mid-fluidity concrete) with rheology parameters. Since the normal strength grade concrete mixture has a relatively high water-to-cement ratio and no SCMs, it is easy to be segregated when superplasticizer is added. Hence, to achieve the mid-fluidity concrete of normal strength grade and high fluidity, preventing segregation of the mixture is inevitable. In this research, using two superplasticizers with different solid concentrations, the flow behaviors and rheological behaviors were assessed by increasing fluidity until the segregation happened. According to the experiment in this research, an unusual behavior in rheology parameters was observed when the concrete mixture started to be segregated. From this results and report, it is expected to contribute on the definition of segregation with rheological test methods.

• Magazine of the Korea Concrete Institute
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• v.22 no.1
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• pp.45-47
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• 2010

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.3
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• pp.268-276
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• 2015

In this study, $CO_2$ reduction type quaternary component high fluidity concrete was produced with more than 80% reduction in cement quantity to increase the use of industrial byproducts and enhance construction performance, thereby reducing $CO_2$ emissions. Furthermore, the quality properties, and $CO_2$ reduction performance of this concrete were evaluated. As a result of the quality evaluation of quaternary component blended high fluidity concrete with $CO_2$ reduction, the target performance could be achieved with a 80% or more reduction of cement quantity by mixing a large amount of industrial byproducts. The required performance level was obtained even though the flow, dynamic, and durability characteristics decreased a little compared to conventional mix. In addition, to analyze the $CO_2$ reduction performance of quaternary component blended high fluidity concrete with $CO_2$ reduction, the life cycle assessment (LCA) of the concrete was performed and the results showed that compared to the conventional mix, the carbon emissions decreased by 62.2% and the manufacturing cost by 24.5%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3704-3712
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• 2012

Recently, antiwashout underwater concrete has been increasingly used for marine foundations of long span bridges. However, to shorten the construction period of antiwashout underwater concrete used in marine foundations, high fluidity antiwashout underwater concrete should be manufactured largely improving fluidity than the previous one. Thus, the objective of this experimental research is to suggest optimum mix proportions of high fluidity antiwashout underwater concrete. For this purpose, concrete specimens containing ground granulated blast furnace slag were manufactured according to the dosage of antiwashout admixture for unit binder contents of 550 and 600kg/$m^3$, respectively. And then, their quality performances such as slump flow, setting time, underwater segregation resistance, and ratio of compressive strength were evaluated according to the related specification of Korea Concrete Institute. It was observed from the test results that the minimum dosage of antiwashout admixture was necessary to satisfy the related specification.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.813-816
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• 2008

Polycarboxylate-type superplasticizer is widely used for producing self-compacting and high-strength concrete and improving concrete durability. This paper discusses the influence of molecular structure of polycarboxylate-type superplasticizer on the fluidity and the rate of heat liberation of ordinary Portland cement paste. The fluidity of cement paste was increased by addition of polycarboxylate-type superplasticizer. The arrival time up to the maximum rate of heat liberation was increased by addition of polycarboxylate-type superplasticizer. The fluidity and the arrival time up to the maximum rate of heat liberation were more influenced by addition of polycarboxylate-type superplasticizer having shorter grafted chain than that having longer grafted chain.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.113-114
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• 2022

The aim of the research is to evaluate the segregation resistivity of the mixture conditions by changing the PVA and borax solutions for thixotropic property on concrete mixture. Since the water addition caused by producing solutions of PVA and borax induces segregation of the concrete mixture, the unit water was reduced by replacing the water amount for PVA and borax solution. By replacing the water from PVA and borax solutions, the segregation was prevented with prefixed concrete mix design and thixotropic properties were also occurred.

• 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.