• Journal of the Korean Ceramic Society
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• v.44 no.11
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• pp.633-638
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• 2007

The setting time of alkali activated slag cement tends to be much faster than ordinary Portland cement, and its compressive strength had been higher from the 1 day but became lower than that of the cement on the 28 days. According to the results of the surface observation, weight loss, compressed strength, and erosion depth tests on the sulphuric acid solution. It has been drawn that alkali activated slag cement has a higher sulphate resistance than ordinary Portland cement, and in particular, the alkali activated slag cement added 5 wt% alumina cement has little deterioration on the sulphuric acid solution. The reason why the alkali activated slag cement has higher sulphate resistance than other hardened cement pastes is that it has no $Ca(OH)_2$ reactive to sulphate ion, and there is little $CaSO_4{\cdot}2H_2O$ production causing volume expansion, unlike other pastes. And it is supposed that $Al(OH)_3$ hydrates with high sulphate resistance, which is produced by adding the alumina cement increases the sulfate resistance.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.281-286
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• 1998

The aim of this study is to compare the development of compressive strength of high-Flowing concrete with maturity and to investigate the applicability of strength prediction models of concrete. An experiment was attempted on the high-flowing concrete mixes using Ordinary portland cement, High belite cement, Blast furance slage cement and replaced Fly-ash of 30% by weight of Ordinary portland cement, the water-binder ratios of mixes being 0.35 and the curing temperatures being 30, 20, 10, 5$^{\circ}C$. Test results of mixes are statistically analyzed to infer the correlation coefficient between the maturity and the compressive strength of high-flowing concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.485-490
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• 2000

Because of occuring easily the crack, debond, lutting on asphalts pavement of bredge decks under traffic's heavy weigt load. We investigated the application of latex modified concrete to resurface and repaire bridge decks for preventing the above problems. Here, Using the ordinary portland cement and high early cement, We rested mix design, workability, compressive strength, adhesive power, drying shrinkage, carbonation, and economic estimation etc. We selected the condition of application to resurface and repaire bridge decks and detected high early cement is superior to ordinary portland cement in results of analyzing the application of the repairing bridge decks and economic estimations.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.5
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• pp.59-67
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• 1998

The object of this study is to investigate the strength characteristics and the freeze-thaw resistance of high strength concrete incorporating fine blast furnace slag. Major experimental variables were the water/cement ratio, maximum size of coarse aggregate, and cement types such as ordinary portland and slag cement. The results were as follows ; The workability of fresh concrete incorporating fine blast furnace slag was better than that of OPC(ordinary Portland cement) in terms of slump. The freeze-thaw resistance showed better than that of OPC, keeping more than 90% of relative modules of elasticity after 506 cycles and showing only a hair crack at surface without serious damage. Thus, the fine blast furnace slag might be recycled at concrete to make high strength concrete at fields.

• Advances in concrete construction
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• v.5 no.2
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• pp.101-115
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• 2017

Cement kiln dust (CKD) is one of the most important waste materials in the cement industry. The large amount of this material, has encouraged researchers to propose new ways to recycle and reuse it. In this paper, effects of adding cement kiln dust to the ordinary Portland cement, on the physical and mechanical properties of ordinary and lightweight concrete were investigated. Results showed that concrete containing CKD, presents lower workability and modulus of elasticity; however, improvements in strength was observed by adding particular amounts of CKD. Eventually, it was found that adding 10% of cement weight CKD is the appropriate percentage for utilizing in manufacturing ordinary and lightweight concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.297-302
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• 2001

SRC pier at KTE 6-1 construction area is a very important structure. Precise control of quality is needed. This pier has 3.50m$\times$3.73m section and 38.20m length. So this structure must be treated as mass concrete and thermal crack caused by hydration heat should be controled. In this project belite cement concrete is used to control the thermal crack. As a result of adapting belite cement concrete perfect control is achieved. Finally, hydration heat FEM analysis of horizontal element is executed for Ordinary Portland Cement concrete and belite cement concrete. In comparison of two results, it is confirmed that using low heat portland cement concrete is necessary.

• Computers and Concrete
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• v.13 no.6
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• pp.695-707
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• 2014

This study investigated the chloride binding isotherms of various cement types, especially the contributions of C-S-H and AFm hydrates to the chloride binding isotherms were determined. Ordinary Portland cement (OPC), Modified cement (MC), Rapid-hardening Portland cement (RHC) and Low-heat Portland cement (LHC) were used. The total chloride contents and free chloride contents were analyzed by ASTM. The contents of C-S-H, AFm hydrates and Friedel's salt were determined by X-ray diffraction Rietveld (XRD Rietveld) analysis. The results showed that OPC had the highest chloride binding capacity, and, LHC had the lowest binding capacity of chloride ions. MC and RHC had very similar capacities to bind chloride ions. Experimental equations which distinguish the chemically bound chloride and physically bound chloride were formulated to determine amounts of the bound chloride basing on chloride binding capacity of hydrates.

• Geomechanics and Engineering
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• v.31 no.4
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• pp.409-422
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• 2022

The use of calcium sulfoaluminate (CSA) cement as a rapid-hardening cement admixture or eco-friendly alternate for ordinary Portland cement (OPC) has been attempted over the years, but the cost of CSA cement and availability of suitable aluminium resource prevent its wide practical application. To propose an effective ground improvement design in sandy soil, this study aims at blending a certain percentage of CSA with OPC to find an optimum blend that would have fast-setting behavior with a lower carbon footprint than OPC without compromising the mechanical properties of the cemented sand. Compared to the 100% CSA case, initial speed of strength development of blended cement is relatively low as it is mixed with OPC. It is found that 80% OPC and 20% CSA blend has low initial strength but eventually produces equivalent ultimate strength (28 days curing) to that of CSA treated sand. The specific OPC-CSA blend (80:20) exhibits significantly higher strength gain than using pure OPC, thus allowing effective geotechnical designs for sustainable and controlled ground improvement. Further parametric studies were conducted for the blended cement under various curing conditions, cement contents, and curing times. Wet-cured cement treated sand had 33% lower strength than that of dry-cured samples, while the stiffness of wet-cured samples was 25% lower than that of dry-cured samples.

• Journal of the Korea Concrete Institute
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• v.16 no.3 s.81
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• pp.369-374
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• 2004

Calcium sulfoalumiante(CSA) was prepared for using natural calcite($CaCO_3$) and industrial by-products and wastes, such as $Al(OH)_3,\;CaSO_4{\cdot}2H_2O$. The mixture of raw materials was fired at 20, 400, 600, $1200^{\circ}C$ for 1h and cooled rapidly in air. The cement replaced by 10 wt% $C_4A_3S$ expansive additives was investigated by the measurement of the hydration products and compressive strength, setting time, expansion at wet curing condition. $C_4A_3S$ was found in x-ray diffraction pattern over the temperature $1200^{\circ}C$. The setting time or the cement pastes added clinkers fired at different temperature was shorter than ordinary portland cement. The compressive strength was higher than the ordinary portland cement about 20~30%. The mainly hydration products were ettringite, and $Ca(OH)_2$. The expansion due to the formation of ettringite during hydration decreased the drying shrinkage of hardened cement rather than the ordinary portland cement.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.445-448
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• 2006

In order to control the temperature crack of massive dam concrete, the selection of appropriate materials like binder, aggregates etc., is essential. To select the optimal mix proportion, ordinary portland cement(Type I) plus 25% of fly ash and low heat portland cement(Type IV) are used as binder, and 80mm of coarse aggregates are used to reduce the amount of binder and compare the compressive strength, hydration temperature and crack index. The results of this study are as following. 1. The strength of Type IV cement is advantageous on the long-term age. 2. According to the temperature measured on mock-up$(1.5m{\times}1.5m{\times}1.5m)$, and realized the thermal analysis, the Type IV cement carried out advantageous to control the thermal crack.