• Journal of the Korea Concrete Institute
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• v.12 no.1
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• pp.79-88
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• 2000

Usually, the expansive additives is used to prevent the occurrence of drying shrinkage in concrete. However it may sometimes be over-added in field due to the insufficient cognition of constructor's, which may cause the serious problems in concrete structures. In this study the experiments are performed to present the expansion properties of concrete by varying the water to binder ratios, unit contents of expansive additives and curing conditions. By the results, the strength showed an increase with the addition of expansion additives from 30kg/㎥ up to 50kg/㎥, and a great decrease by contraries if the larger amount are added. Also the more the expansion additives were used, the more length change occurred in concrete. In view of the curing conditions, the concrete by air cured appeared a little expansion even the unit expansion additives increased, which showed an opposite inclination of that with standard curing. This could be explained by the less occurrence of hydration in air condition which also lead to the little expansion of concrete. Hence the expansion concrete to be cured in water or moisture condition became an especial important thing. concrete using expansive additives showed that high expansion was taken place with the rise of temperature.

• Journal for History of Mathematics
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• v.13 no.2
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• pp.105-120
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• 2000

In this study, it is certified that the golden ratio exists in the plants, the animals and human bodies(appearance), and is considered how much the ratio of positive and negative is in the psychological, political, social and cultural aspects. The result of this study shows that the golden sections or golden rectangles of the plants(N=58), the insects(N=44), the animals(N=21) and human bodies(N=260) are equal to $0.620{\pm}0.117$, $0.632{\pm}0.203$, $0.625{\pm}0.138$ and $0.60{\pm}0.169$, respectively. The slope in the regression analysis is equal to 0.627(R-square=0.925, p-value=0.0001). Whereas, for the public opinion poll, the ratios($mean{\pm}st.dev.$) of positive and negative of the public mental phenomena are equal to $0.508{\pm}0.179$, $0.808{\pm}0.216$ and $0.711{\pm}0.128$ in the political, economical, and sociocultural aspects, respectively. The slope in the regression is equal to 0.674(R-square=0.764, p-value=0.016). As results, we show that the golden ratio exists in the plants, the animals and human bodies in nature. This shows that the public mental phenomena has some more negative aspects than positive aspects and explains the shrinkage of the public mental phenomena in the economical field.

• Textile Coloration and Finishing
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• v.18 no.2 s.87
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• pp.39-45
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• 2006

The aim of this work is to develop sense-differentiated textiles using Thick-Thin polyester yarn(T-T yarn) with finer than 1 denier mono filament. The ITY(Interlace Textured Yarn) using T-T yarn with various over feed ratios of PET filament was manufactured with different shrinking percentage of core yarn and then the fabrics were woven on the same weaving 100m using ITY produced. The mechanical properties and the handles of the fabrics were examined with KES-FB system suggested by Kawabata. The shrinkage of ITY was increased with decreasing over feed ratio and increased with increasing heat treatment temperature of T-T yarn. The initial elasticity modulus of ITY was decreased with increasing over feed ratio and heat treatment temperature of T-T yarn. The tensile energy of fabrics was decreased with increasing of over feed ratio, but bending rigidity and shear rigidity of fabrics were increased with increasing of over feed ratio of PET filament. The results indicate that the fabric using T-T yarn with finer than I denier mono filament can be used for the purpose of sense-differentiated textile.

• Fibers and Polymers
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• v.7 no.3
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• pp.295-304
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• 2006

High-bulk worsted yams with different shrinkable and non-shrinkable acrylic fibers blend ratios are produced and then single jersey weft knitted fabrics with three different structures and loop lengths are constructed. The physical properties of produced yams and compression properties of produced fabrics at eight pressure values (50, 100, 200, 500, 1000, 1500 and $2000 g/cm^2$) were measured using a conventional fabric thickness tester. Then, weft-knitted fabric compression behavior was analyzed using a two parameters model. It is found that at 40 % shrinkable fibre blending ratio the maximum yam bulk, shrinkage, abrasion resistance and minimum yarn strength are obtained. It is also shown that high-bulk acrylic yarn has the highest elongation at 20 % shrinkable fibre blend ratio. The statistical regression analysis revealed that the compression behavior of acrylic weft-knitted fabrics is highly closed to two parameter model proposed for woven fabrics. It is also shown that for weft-knitted structure, there is an incompressible layer (V') which resists against high compression load. Acrylic weft-knitted fabrics with knit-tuck structure exhibit higher compression rigidity and lower softness than the plain and knit-miss structures. In addition, at 20 % shrinkable fibre blend ratio, the high-bulk acrylic weft-knitted fabrics are highly compressible.

• Advances in materials Research
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• v.4 no.1
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• pp.45-60
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• 2015

This paper aimed to investigate the effect of MWCNTs on properties of slag Geopolymeric mortar. Geopolymeric matrices containing different MWCNTs concentrations (0.0, 0.1, 0.2, 0.3 and 0.4 % by weight of the used binder) were synthesized. The Geopolymer mortar composed of aluminosilicate slag to sand (1:2), while the alumino silicate source binder composed of 50% air cooled slag and 50%water cooled slag both passing a sieve of $90{\mu}m$, while the sand passing a sieve of 1 ml. The materials prepared at water/binder ratios in a range of 0.34-0.39% depending on the added MWCNT, whereas the Gelenium Ace-30 superplasticizer used in the ratio of 1.4-2.2% from the total dry weight for better dispersion of MWCNT under sonication for 15 min. Alkaline activation of the Geopolymer mortar was carried by using of 6% NaOH. Curing was performed under temperature of $40^{\circ}C$ and 100% R.H. Results showed that the addition of MWCNTs enhanced the resulting amorphous geopolymer structure with marked decrease in the drying shrinkage as well as water absorption specially when using 0.1% MWCNT, while further increase in MWCNTs results in agglomeration in MWCNT within the matrix and so hinder the propagation of Geopolymerization reaction and negatively affect the formed geopolymer structure.

• Computers and Concrete
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• v.7 no.1
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• pp.53-62
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• 2010

Dredged silt from reservoirs in southern Taiwan was sintered to make lightweight aggregates (LWA), which were then used to produce high-performance lightweight aggregate concrete (HPLWC). The HPLWC was manufactured using different amounts of mixing water (140, 150, and 160 $kg/m^3$) and LWA of different particle densities (700, 1100, and 1500 $kg/m^3$) at different W/b ratios (0.28, 0.32, and 0.4). Results show that the lightweight aggregates of dredged silt taken in southern Taiwan perform better than the general lightweight aggregates. In addition, the HPLWC possessed high workability with a slump of 230-270 mm, and a slump flow of 450-610 mm, high compressive strength of over 40 MPa after 28 days of curing, good strength efficiency of cement exceeding $0.1MPa/kg/m^3$, low thermal conductivity of 0.4-0.8 $kcal/mh^{\circ}C$, shrinkage of less than $4.8{\times}10^{-4}$, and high electrical resistivity of above 40 $k{\Omega}-cm$. The above findings prove that HPLWC made from dredged silt can help enhance durability of concrete and provide and an ecological alternative use of dredged silt.

• Magazine of the Korea Concrete Institute
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• v.8 no.5
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• pp.135-143
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• 1996

Diffusion of water in hardened cement concrete and mortar influences on the dry shrinkage. creep. modulus of' elasticity, etc. In general, water loss through drying process in polymer-modified concrete and mortar is small compared with that of unmodified concrete and mortar due to the films formed by polymer as cement modifieder. The purpose of this study is to investigate the diffusion process of water in the polymer-modified mortars. The polymer-modified mortars using three polymer dispersions and epoxy resin are prepared with various polymer-cement ratios, and water diffusion coefficient of polymer-modified mortars according to inside water content is calculated. From the test results, the water diffusion coefficient of polymer modified mortars i s smaller than that of unmodified mortars and decreases with increasing polymer cement ratio.

• Journal of Radiation Industry
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• v.4 no.3
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• pp.271-276
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• 2010

Epoxy resin has wide application in various industrial fields because of their good mechanical strength, superiority adhesion and low shrinkage etc. And the typical curing method for epoxy resins is thermal and press compaction. However, a curing method was used electron beam process in this study. Epoxy acrylate was fabricated from mixture of epoxy, acrylic acid, tetraphenylporphyrin (TPP) and hydroquinone monomethyl ether (MEHQ) with mole ratios. Then electron beam irradiation effect on the curing of the epoxy acrylate resin was investigated various absorption dose in nitrogen atmospheres at room temperature. The dynamic mechanical and thermal properties of the irradiated epoxy acrylate resins were characterized using dynamic mechanical analysis (DMA) and thermogravimetric analyzer (TGA). And the tensile and flexural strength were measured by an universal tensile machine (UTM).

• Geomechanics and Engineering
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• v.6 no.2
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• pp.139-151
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• 2014

Mudstone is a very common rock that, when in contact with water, can exhibit considerable volume change and breakdown. This behavior of mudstone is frequently encountered in geotechnical engineering and has a considerable influence on infrastructure stability. This is particularly important in the present work, which focuses on mitigating the harmful properties of mudstone. The samples studied are of Permian Age mudstone from Shandong Province, China. Modification tests using organic silicone additive material were carried out. The mechanisms of physical properties modification of mudstone were comparatively studied using corresponding test methods, and the modification mechanism of organic silicone additive material acting on mudstone was analyzed. The following conclusions were drawn. The surface texture and characters of mudstone changed dramatically, surface character turns from hydrophilic to hydrophobic after organic silicone additive material modification. The changes in the surface character indicate a reduction in the water sensitivity of mudstone. After modification, the shape of porosity and fracture of mudstone changed unremarkable, and the total and free expansion ratios decreased obviously, whereas the strength increased markedly.

• Applied Chemistry for Engineering
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• v.25 no.2
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• pp.181-187
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• 2014

In order to use the spherical atomizing reduction steel slag (ladle furnace slag, LFS) instead of the fine aggregate of polymer concrete composites, various specimens were prepared with various replacement ratios of atomizing reduction steel slag and the addition ratios of polymer binder. Physical properties of these specimens were investigated through the absorption test, the compressive strength test, the flexural strength test, the hot water resistance test, the pore analysis and the micro-structure using scanning electron microscope. Results showed that the compressive strength and flexural strength of specimens with 7.5% of polymer binders increased with the increase of replacement ratios of atomizing reduction steel slag, but those of the specimens with 8.0% or more of polymer binders showed a maximum strength at a certain replacement ratio due to the material segregation causing the increase of fluidity. By hot water resistance tests, the compressive strength, flexural strength, average pore diameter, and bulk density decreased but the total pore volume and pore diameter increased. It was concluded that the amount of polymer binders could be reduced by maximum 23.8%, because the workability of the polymer concrete was remarkably improved by using the atomizing reduction steel slag instead of fine aggregate. However, since the use of atomizing reduction steel slag decreased the resistance of the polymer concrete to hot water, further studies are required.