• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.3
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• pp.9-17
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• 2010

This study aims to evaluate a porous concrete using hwang-toh, blast furnace slag and blast furnace slag (BFS) cement instead of type I cement. The tests that were carried out to analysis the properties of porous hwang-toh BFS cement concrete included compressive strength, continuous void ratio, absorption rate, and pH value, repeated freezing and thawing test were conducted. Test results indicated that the performance in porous hwang-toh concrete are effective on the kaoline based binder materials. The pH value were shown in about 9.5 ~ 8.5. The compressive strength was increased and void ratio was decreased with increasing the kaoline based binder materials, respectively. The void ratio and compressive strength were in the range of about 21 ~ 30 %, 8 ~ 13 MPa, respectively. The increased in void ratio of more than 25 % is showed to reduce the resistance of repeated freezing and thawing. Also, the resistance of repeated freezing of thawing and the compressive strength of porous hwang-toh BFS cement concrete are independent with hwang-toh content and BFS cement amount. But, the void ratio was decreased with increasing the high volume hwang-toh contents (more than 15 %).

• Journal of the Korean Ceramic Society
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• v.51 no.2
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• pp.82-87
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• 2014

Due to the revised Korean standard KS L 5201 for Ordinary Portland Cement (OPC), the use of mixed cement has grown from 5% to 10%. This study investigates the hydration behavior of $C_3A$, asit is a cement mixture that is more commonly used than granulated blast furnace slag or limestone alone. Paste samples were prepared with either granulated blast furnace slag or limestone alone. Each sample was compared with the widely used Rietveld method with a cement mixture containing blast furnace slag or limestone. The hydration behavior of $C_3A$ in each OPC sample was assessed and results were analyzed. Granulated blast furnace slag promotes a high initial level of ettringite, but as the days passed, it promotes an increase in monosulfate, leading to cracks and expansion due to the penetration of sulfates in the solution. However, when limestone is added to the mixture, a transformation of ettringite to monosulfate occurs in the presence of the $CaCO_3$ in the limestone. It is considered that this produces hemi-carbonate and mono-carbonate and thus maintains the ettringite level.

• Resources Recycling
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• v.18 no.3
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• pp.42-48
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• 2009

Since there are $OH^-,\;[SiO_4]^{4-}$ ion of high concentration at early hydration in the system added with activator (NaOH+$Na_2OSiO_2$) in the blast furnace slag, different from cement hydration, hydration progresses fast without induction period and forms reaction rim around the blast furnace slag grain. $0.6{\mu}m$ reaction rim was formed around the blast furnace slag grain from the 1 day of reaction period, and the thickness of reaction rim increases over the reaction time, growing to $1{\mu}m$ on the 28 days. Unreacted blast furnace slag grain deformed from angular shape to the spherical shape. Mole ratio of Ca/Si tends to decrease from inside of blast furnace slag grain to reaction rim. Difference of Ca/Si mole ratio between reaction rim and inside the blast furnace slag grain decreased and generated hydrate was a poor crystalline CSH(I) with Ca/Si mole ratio less than 1.5.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.191-194
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• 1999

Recently in Korea, may workers have reported the effects of the granulated blast furnace slag[BFS] of high fineness on the strength development of slag cement. We have studied the effect of slag fineness on the strength development of mortar with curing conditions, in order to get the basic data of high strength concrete using BFS. In this paper, we discussed the effects of slag fineness and porosity of mortar and the reaction of slag in hardened slag cement.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.295-296
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• 2023

This study evaluated the compressive strength after making mortar with low cement composition for carbon-neutral steam curing to respond to climate change. Blast furnace slag, fly ash, and ultra-high powder fly ash were used as substitutes for cement. The cement substitute was used at 40% of the mass of cement, and after steam curing, the compressive strength was measured on the 1st, 3rd, 7th and 28th days of age. As a result of the experiment, at the age of 1 day, the mixture using only cement showed the highest strength, but from the 3rd day, the specimen using ultra-high powder showed a high strength development rate, followed by blast furnace slag and fly ash.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.473-476
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• 2006

As a part of efforts to obtain high quality and economical efficiency of concrete, blast-furnace slag has been utilized by means of cement replacement. Therefore superior performance can be ensured, environmental pollution can be prevented and economical advantage can be obtained with utilization by cement replacement. But the studies on the blast-furnace slag are not systematic and reasonable. So, it was planed that basic data in regard to technique of manufacturing and economic improvement of concrete is showed with experimental comparison and investigation of Fluidity and engineering properties of concrete utilizing blast-furnace, industry by-product, as cement replacement in this study.

• Journal of the Korean Society of Safety
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• v.30 no.4
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• pp.120-127
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• 2015

The aim of the present study is to investigate some characteristics of concrete according to addition of blast furnace slag and alkali-activator dosages. Blast furnace slag was used at 30%, 50% replacement by weight of cement, and liquid sulfur having NaOH additives was chosen as the alkaline activator. In order to evaluate characteristics of blast furnace slag concrete with sulfur alkali activators, compressive strength test, total porosity, chloride ions diffusion coefficient test were performed. The early-compressive strength characteristics of blast furnace slag concrete using a sulufr-alkali activators was compared with those of reference concrete and added 30, 50% blast furnace slag concrete. Also, Blast furnace slag concrete using sulfur-alkali activators enhanced the total porosity, chloride ions diffusion coefficient than two standard concrete. Alkali-activated blast furnace slag concrete was related to total porosity, compressive strength and chloride ions diffusion coefficient each others. As a result, it should be noted that the sulfur-alkali activators can not only solve the demerit of blast furnace slag concrete but also offer the chloride resistance of blast furnace slag concrete using sulfur alkali activators to normal concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.18-19
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• 2017

In this study, hardening characteristics and microstructure of blast furnace slag-cement mortar replaced alpha-calcium sulfate hemihydrate were analyzed. As a result of replacing alpha-calcium sulfate hemihydrate with 0, 10, 20, 30%, it was confirmed that the initial and final setting times are faster than that of blast furnace slag-cement mortar. The compressive strength of the specimens containing alpha-calcium sulfate hemihydrate decreased in the range of 42 ~ 76% at age 28 days compared with blast furnace slag-cement mortar. In the case of replacing the alpha-calcium sulfate hemihydrate, the shrinkage did not occur more rapidly than the cement mortar, but the slope of the strain curve showed a linear behavior. The results of scanning electron microscopy images analysis showed that the formation of ettringite was increased at alpha-calcium sulfate hemihydrate replaced mortar.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.132-133
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• 2016

The Present that environmentally friendly policies at issue in the world recently, construction sector and other sectors are working on reducing CO₂. Cement production during in the construction sector, CO₂ is being caused in large quantities. Therefore, this study was secure the basic date that not use cement and use blast furnace slag and fly ash HFA, polysilicon in industrial byproducts about cement non-cement matrix.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.3-9
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• 2002

Paper sludge ash was assured as material of a sort of pozzolan. For the reason of fluidity decrease caused by the strong absorption of paper stooge ash and the decrease of compressive strength in case of using over30% replacement by the weight of cement, paper sludge ash is not suitable for blending material. Therefore, it is necessary to find proper replacement ratios between paper sludge and blast furnace slag to insure compressive compensation and appropriate slump. Accordingly, as varied the blending ratios of paper sludge and blast furnace slag, testing mortar was made. This study was aimed to investigate the possibility of using blending replacement of paper sludge ash and blast furnace slag throughout compressive test, flow test, SEM(Scanning Eletron Microscope), MIP(Mercury Intrusion Porosity test), and TG-DTA(Thermal analysis).