• Cement Symposium
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• no.6
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• pp.82-86
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• 1978

• Journal of the Korea Concrete Institute
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• v.13 no.2
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• pp.175-183
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• 2001

Immersion tests with artificial seawater were carried out to investigate the resistance to seawater attack of 5 types of cement matrices. From the results of compressive strength and length change, it was found that blended cement mortars due to mineral admixtures, were superior to portland cement mortars with respect to the resistance to seawater attack. Moreover, XRD analysis indicated that the peak intensity ratio of low heat portland cement(LHC) paste, in portland cement pastes, had better results, and so did that of blended cement Paste. Pore volume of pastes by mercury intrusion porosimetry method demonstrated that total pore volume of ordinary portland cement(OPC) paste had a remarkable increase comparing with that of other pastes. In case of immersion of artificial seawater, the use of ground granulated blast-furnace slag and fly ash, however, showed the beneficial effects of 56% and 32% in reduction of total pore volume, respectively.

• Journal of the Korean Society for Railway
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• v.5 no.2
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• pp.61-69
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• 2002

Recycling of dredged soils as construction materials is experimently discussed in this paper. The strength of light-weighted soils(LWS) consisting of expanded polystyrene(EPS), dredged soils and cement is characterized by uniaxial and triaxial compression tests with varying initial water contents of dredged soils, the EPS volume and cement contents, and expanded ratio of EPS. Test results show that the strength of light-weighted soils increases with adding cement contents, whereas the strength increases with decreasing initial water contents of dredged soils and expanded ratio of EPS. It was, however, found that increasing the EPS volume makes a lower the strength of light-weighted soils.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.881-884
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• 2006

Wasted phosphogypsum is a by-product from the phosphoric acid process of manufacturing fertilizers. It consists mainly of $CaSO_4{\cdot}2H_2O$ and contains some impurities. The purpose of this study is to utilize wasted phosphogypsum into an admixture for concrete products cured by steam This paper is to investigate the strength properties of cement composites containing high volume phosphogypsum. The cement composites were composed of OPC, phosphogypsum, fly-ash and granulated blast-furnace slag with activators. As a result, the strength of cement composites containing high volume wasted phosphogypsum were shown high level when granulated blast-furnace slag was mixed. Therefore, PG could be used as a steam curing admixture for concrete 2th production with reduction of OPC.

• Computers and Concrete
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• v.7 no.5
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• pp.421-435
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• 2010

This paper utilizes the modified Davis model and the mode coupling theory, as parts of the electrolyte solution theory, to investigate the diffusivity of the ion in concrete. Firstly, a computational model of the ion diffusion coefficient, which is associated with ion species, pore solution concentration, concrete mix parameters including water-cement ratio and cement volume fraction, and microstructure parameters such as the porosity and tortuosity, is proposed in the saturated concrete. Secondly, the experiments, on which the chloride diffusion coefficient is measured by the rapid chloride penetration test, have been carried out to investigate the validity of the proposed model. The results indicate that the chloride diffusion coefficient obtained by the proposed model is in agreement with the experimental result. Finally, numerical simulation has been completed to investigate the effects of the porosity, tortuosity, water-cement ratio, cement volume fraction and ion concentration in the pore solution on the ion diffusion coefficients. The results show that the ion diffusion coefficient in concrete increases with the porosity, water-cement ratio and cement volume fraction, while we see a decrease with the increasing of tortuosity. Meanwhile, the ion concentration produces more obvious effects on the diffusivity itself, but has almost no effects on the other ions.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.6
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• pp.151-158
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• 2012

This study will not only prove experimental dynamic properties which are classified to slump, compressed strength, bending strength and toughness index blast-furnace cement concrete with polypropylene (PP) fiber that refer properties and volume of it, but also establish a basic data in order to use PP fiber reinforced blast-furnace cement concrete. The slump didn't changed by PP fiber volume $5kgf/m^3$ because of flexibility of fiber in despite of loose mixing. The reason why the slump decreased steadily by PP fiber volume $3kgf/m^3$ was rising contact surface of water. The compressed strength indicated a range of 19.49~26.32 MPa. The tensile strength indicated a range of 2.10~2.44 MPa. The bending strength was stronger about 3~16 % in case of mixing with PP fiber volume than normal concrete. The flexure strength indicated a range of 4.30~4.83 MPa. The toughness indicated a range of $0{\sim}19.88N{\cdot}mm$ and was stronger about 6.7 times in case of PP fiber volume $9kg/m^3$ than PP fiber volume $1kg/m^3$. The pavement with PP fiber volume over such a fixed quantity in the roads of a respectable amount load can have a effect to prevent not only resistance against clack but also rip off failures.

• International Journal of Concrete Structures and Materials
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• v.2 no.2
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• pp.161-167
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• 2008

Optimization of concrete mixing system is very important for the production of quality mixture of concrete and requires very complicated, specialized knowledge as there are a variety of variables that influence the result. One of the methods of optimizing the concrete mixing system is to minimize the volume of cement paste which, in turn, means maximizing the volume of aggregate. The purpose of this study is to determine the minimum volume of cement paste used in the design of concrete mixture and to design the optimum concrete mixing system based on the fluidity of mortar and concrete. In determining the minimum volume of cement paste, experiments of mortar and concrete were performed based on their workability, material segregation and bleeding. Type of aggregate, granularity distribution and sand percentage were used as test parameters and measurements were taken of the distribution of granularity, usage of HRWRA, minimum volume of paste and drying shrinkage and compressive strength of concrete.

• Journal of the Korean Ceramic Society
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• v.37 no.6
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• pp.576-582
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• 2000

Two type of expanding cement generally referred to as CSA with Hauyne(3CaO 3Al2O3 CaSO4) and Quick lime(CaO). Hauyne is formed to ettringite when there are presented with CaO and CaSO4, and CaO reacts wtih water to form Ca(OH)2. REcently, the mechanism of compensation and expand mortar or concrete tend to same and it has been used improving on its shrink property. The volume of cement paste varies with its water content shrink with drying and re-wetting. Concrete and mortar works are required shrinking compensation and expansion properties to reduce of potential crack. The use of expansion cement may improve on its shrinking volume changes. CSA dosages for shrinking compensation limited by cement weight, but obtained difference expansion rate with varied W/C or inorganic admixture. This paper studies expansion rate according to expansion cement dosages, water and inorganic admixtures as Silica fume. Therefor, the expansion factor has to considered before the application.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.407-410
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• 2005

This research investigates experimentally an effect on the properties of the combined high flowing concrete by mix design factors. The purpose of this study is to determine the optimum mix proportion of the combined high flowing concrete having good flowability, viscosity, no-segregation and design strength(40.0MPa). For this purpose, trial mixings used belite cement+lime stone powder(LSP) are tested by mix design factors including water-cement ratio($47.9\~54.0\%$), fine aggregate volume ratio($41\~45\%$) and coarse aggregate volume ratio($41\~45\%$). As test results of this study, the optimum mix proportion for the combined high flowing concrete is as followings. Water-cement ratio $51.0\%$, fine aggregate volume ratio $43{\pm}1\%$ and coarse aggregate volume ratio $0.30{\pm}0.05m^3/m^3$ and replacement ratio of LSP $42.7\%$.

• Computers and Concrete
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• v.4 no.2
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• pp.157-166
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• 2007

The paper considers a theoretical model to study sulfate ion diffusion in saturated porous media - cement based mineral composites, accounting for simultaneous effects, such as filling micro-capillaries (pores) with ions and chemical products and liquid push out of them. Pore volume change and its effect on the distribution of ion concentration within the specimen are investigated. Relations for the distribution of the capillary relative radius and volume within the composite under consideration are found. The numerical algorithm used is further completed to consider capillary size change and the effects accompanying sulfate ion diffusion. Ion distribution within the cross section and volume of specimens fabricated from mineral composites is numerically studied, accounting for the change of material capillary size and volume. Characteristic cases of 2D and 3D diffusion are analyzed. The results found can be used to both assess the sulfate corrosion in saturated systems and predict changes occurring in the pore structure of the composite as a result of sulfate ion diffusion.