• 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 Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.271-279
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• 2016

This study examines the properties of high-fluidity concrete after adding copper slag as a mineral admixture. For this purpose, the replacement ratio of cement to copper slag was varied to 0, 10, 20, 30, 40, and 50%. A slump flow test, reach time slump flow of 500 mm, and a U-Box and O-lot test were conducted on the fresh concrete. The compressive strength of the hardened concrete was determined at 3, 7, 14 and 28 days. According to the test results, the workability, compaction, and compressive strength of the high-fluidity concrete increased when replacing 30% of the cement with copper slag. These parameters decreased for all material ages with more than 30% copper slag, which was the optimal mixture ratio.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.506-513
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• 2022

In this paper, as part of a study for carbon neutrality, the quality properties of quaternary component high-fluidity concrete, which significantly replaced up to 80 % of the cement usage by using three industrial by-products, were evaluated. As a result of the evaluation, even if a large amount of industrial by-products were replaced by more than 80 % of the amount of cement used, it was possible to obtain quality that satisfies the target performance in all concrete mix. In the case of flow properties, mechanical properties, and durability, compared to the existing standard concrete mix, the performance tends to decrease, but it is judged that the performance above the required performance level can be satisfied. When considered comprehensively, the quaternary component High-Fluidity Concrete with a large mixing amount of fine powder of blast furnace slag showed relatively good performance.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.87-91
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• 2008

The study examined fire resistance of concrete followed by change of mixed rate in PP and NY composite fiber and the results were as follows. In the event of fluidity in concrete not set, plane satisfied 600±100, its target slump flow, and fluidity was reduced as organic fiber's mixed rate was increased. Air amount satisfied 3.0±1.0, its target air amount, and didn't have distinct differences in reduction and increase according to organic fiber's kind and change of its mixed rate. However, it had a tendency that fluidity was reduced as the mixed rate was increased. In characteristics of hardening concrete, the 28th day compressive strength followed by organic fiber's kind and change of its mixed rate didn't have a lot of differences and satisfied high strength scope as about 70MPa. In spalling characteristics after fire resistance test, spalling was happened in non-mixture, plane combination, and P1N0. In other combinations, spalling resistance was happened. The relic compressive strength rate was 56%, the best condition, in P3N1(PP0.03%, NY0.01% compositeness) mixing PP fiber with NY fiber at once.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.4
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• pp.195-202
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• 2004

In this study, it was founded to make the optimal mixture for producing concrete which is self-compacting, yet, and generates low heat of hydration by using flyash, blast furnace slags and limestone powders as binders in addition to cement while using super-plasticizers and viscosity agents as admixture agents. The structural behaviors of the concrete produced with the selected mixture were compared with those of the concrete currently using for construction of nuclear power plants. The study shows that the blended high fluidity concrete including limestone is better in workability and durability than the concrete currently in use for nuclear power plants.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.81-82
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• 2011

This paper is to compare and analyze WOE created by emulsifying waste oil & WOES added by stimulant with the existing SR in order to solve the problem of strength and reduction in fluidity occurring in time of the use of waste oil to reduce the autogenous shrinkage of high strength mortar. As experimental results, in case of WOE, there almost never happened a drop in fluidity at 1% replacement and compressive strength also showed the strength value similar to Plain. On the other hand, the effect of strength improvement consequent upon the use of stimulant was found to be insufficient. The change of autogenous shrinkage generally showed a better reduction effect in shrinkage comparing to Plain. In case of WOE1, reduction effect in autogenous shrinkage was found to be more excellent than the existing SR. Accordingly, WOE1 is analyzed to be desirable if reduction in autogenous shrinkage, strength & up to the aspect of fluidity are taken into consideration.

• 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.

• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.1071-1076
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• 2001

As a rule, in case of CFT for high-rise building, high strength concrete is required since it should have high fluidity, segregation resistance and large proportion of cement per unit considering the filling beneath the diaphragm. However, regarding the low-rise building under 20 stories, it is somewhat difficult to use high strength concrete. This is a fundamental study to develop a concrete with normal strength and high fluidity for CFT of low-rise building, whose Purposes are in speculating several kinds of changes in concrete's characteristics through various experiments and offering basic documents for practicalization in site and production through mock-up test.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.393-394
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• 2010

This paper was examined the plastic viscosity and yield stress of paste and mortar on the part of the research to develop low viscosity and high fluidity concrete for high pumpability. Through this study, we examined the suitable material properties of paste and mortar to low viscosity and high fluidity concrete for high pumpability.