• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.11a
• /
• pp.281-286
• /
• 2001

The utilization of metakaolin as a pozzolanic material for mortar and concrete has received considerable attention in recent years. This paper estimates the fundamental properties of metakaolin as a pozzolanic material in view of fluidity and compressive strength of cement paste and mortar in comparison of silica fume, fly ash and slag. The results show that in order to obtain the same initial fluidity, metakaolin needs higher dosage of PNS superplasticizer than fly ash and slag, however, less dosage than silica fume. In view of compressive strength of mortar, metakaolin exhibits much higher compressive strength than fly ash and slag, and similar compressive strength with silica-fume when 10 % of cement is replaced with a pozzolanic material.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.04a
• /
• pp.95-101
• /
• 1999

This study was performed to evaluate the characteristics of workability and strength of the concrete containing mineral admixtures such as flyash, blast furnace slag, zeolite powder. As a result, considering their workability and strength, the optimum replacement ratio of them to plain concrete were obtained for each ternary admixture. This increased compressive strength was ascribed to both the closer parkinof fine particles and pozzolan reactivity of powders. This work showed that could be effectively utilized as a blending material without any decrease in the strength of early hydration stage. On the other hand, we found that the compressive strength at early ages ternary ordinary and high strength concrete untill 7 days was small, but that ternary concrete at 28days was highly increased about 31% and 15% extent.

• Journal of the Korea Concrete Institute
• /
• v.12 no.3
• /
• pp.11-19
• /
• 2000

It has been reported that few manufacturers of cement mortar for precast products use chemical and mineral admixture due to the absense of restrictions related to the application of admixture and the poor manufacturing facilities. Therefore, this paper is intended to contribute to the improvement of quality by investigating the properties of cement mortar for precast products using fly ash, blast furnace slag and AE water reducing agent. According to the test results. it was found that the cement mortar products using fly ash and AE water-reducing agent had better qualities than those of ordinary portland cement.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.515-516
• /
• 2009

Recently, A lot of roads, railroads and tunnels are constructed for development of industrialization and efficient use of national land. So, we have focused on to figure out the best combination between Slag powder and Mortars with Accelerator to repair of tunnel structure.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.369-370
• /
• 2010

We conducted this study to compare material and mechanical properties in accordance with the type and amount of chemical admixtures used for reducing water and compensation for strength. There is a purpose to characterize setting time and strength of concrete, and apply to derive field mixture design.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.781-786
• /
• 2003

This study has focused on the possibility for recycling tailings from the Sangdong tungsten mine as admixture for concrete. The XRD(X-ray diffraction analysis) and PSA(Particle size analysis) were performed to find mineralogical characteristics. As a result of XRD analysis, the tailings were composed of quartz, feldspars and muscovites, and C-S-H and quartz were found in cement mortar. As a result of KSLT for cement mortar mixed with tailings, most of heavy metals were determined as below the guide line for waste material. In addition, the setting time and compressive strength of cement mortar mixed with tailings were investigated. It was indicated that the initial and final set were retarded according to increasing replacement. The compressive strength of mortar was decreased with increasing replacement.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.775-780
• /
• 2003

The propose of this study is to discover concrete secondary products for proper mixing by lightweight concrete. The standard of water ratio 50% and weight substition 0%, 10%, 20% by Fly-ash. When produce manufactures, there use for maintain its form weight substition and addition among the viscosity agent each Silica-fume and Hydroxy propyl methyl cellulos. Testing method was to operate slump, air content, compressive strength test, rapid freezing and thawing test. The result of this study is appeared when substition Fly-ash generally it had better use Silica-fume.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2003.05a
• /
• pp.89-94
• /
• 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 Korea Concrete Institute Conference
• /
• 2005.05b
• /
• pp.193-196
• /
• 2005

In this study, the purpose is to suggest the data on mixing ratio which effects on the carbonation of concrete by replacing various admixture such as silica fume, fly ash, slag powder. Thus, we have experimented the accelerated test on the carbonation related to hardened body of the concrete which was admixed by slag powder, silica fume, fly ash and it was cured for 4 weeks in carbonation accelerator after 28 days curing water. The result of this experiment showed that carbonation speed increased highly when admixtures be used to replacing by growing of admixture ratio. especially, the test sample which was replaced with silica fume 15$\%$ and slag powder 40$\%$, was promoted highly to carbonation.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.05b
• /
• pp.345-348
• /
• 2005

This paper presents the result of adiabetic temperature rise and fundamental properties of concrete combining admixtures. According to results, difference of setting time with I5.5hours is observed between S-P and R-F30 mixture. Based on the adiabetic temperature rise test, 8$^{circ}C$of heat producted occurs between E-P and R-F30 mixture. is applied to estimate the temperature rising under adiabetic curing condition, which exhibits closer consistency with tested value. The function mentioned above can account for the effect of dormant period in hydration process at early stage on hydration heat production. It reveals that the consideration of placing layer based on the mixture adjustment(E-P mixture at top layer and R-F30 mixture at bottom layer) in mass concreting will contribute to reduce hydration heat as well as alleviate tensile stress discrepancy between placing layer.