• Advances in concrete construction
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• v.9 no.4
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• pp.387-395
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• 2020

This study has been carried out in two-phases to develop Fiber Reinforced Self-Compacting Concrete (FRSCC) performance. In the first phase, the composition of the quaternary composite binder compromised CEM I 42.5N (58-70%), Rice Husk Ash (25-37%), quartz sand (2.5-7.5%) and limestone crushing waste (2.5-7.5%) were optimized. And in the second phase, the effect of two fiber types (steel brass-plated and basalt) was investigated on the SCC optimized with the optimum CB as disperse reinforcement at 6 different ratios of 1, 1.2, 1.4, 1.6, 1.8, and 2.0% by weight of mix for each type. In this study, the theoretical principles of the synthesis of self-compacting dispersion-reinforced concrete have been developed which consists of optimizing structure-formation processes through the use of a mineral modifier, together with ground crushed cement in a vario-planetary mill to a specific surface area of 550 m2 / kg. The amorphous silica in the modifier composition intensifies the binding of calcium hydroxide formed during the hydration of C3S, helps reduce the basicity of the cement-composite, while reducing the growth of portlandite crystals. Limestone particles contribute to the formation of calcium hydrocarbonate and, together with fine ground quartz sand; act as microfiller, clogging the pores of the cement. Furthermore, the results revealed that the effect of fiber addition improves the mechanical properties of FRSCC. It was found that the steel fiber performed better than basalt fiber on tensile strength and modulus of elasticity; however, both fibers have the same performance on the first crack strength and sample destruction of FRSCC. It also illustrates that there will be an optimum percentage of fiber addition.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.5
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• pp.629-632
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• 2004

The objectives of this study were to determine the effects of substituting bread by-product (BBP) for barley grain in high concentrate fattening diets for kids on nutrient intake, growth performance, and nutrient digestibility. Twenty-eight Baladi kids (body weight=17.1${\pm}$1.0 kg) were assigned randomly to 4 experimental finishing diets (7 kids/treatment) in a completely randomized design for 70 days. The control (CON) diet contained 20, 60, 11, 7 and 2% (DM basis) alfalfa hay, barley grain, soybean meal, corn grain, and mineral and vitamin mix, respectively. Bread by-product substituted barley grain by 10, 20 and 30% of the diet DM in the LBBP, MBBP, and HBBP diets, respectively. Dry matter intakes for the CON, LBBP and MBBP diets were similar (p>0.05; avg.=592 g/day), however, kids fed the HBBP diet had a lower (p<0.05) DM intake (451 g/day). Organic matter and CP intakes showed similar patterns to that observed for DM. Dietary treatments did not affect (p>0.05) average daily gain for kids fed the CON, LBBP and MBBP diets (avg.=150 g/day). Final body weights for kids fed the CON, LBBP and MBBP diets (avg. 27.1 kg) were greater (p<0.05) than for kids fed the HBBP diet (23.7 kg). Feed to gain ratio was greater for the CON, LBBP and MBBP diets (avg. 3.9) compared with the HBBP diet (5.0). No significant (p>0.05) effect of the dietary treatment was observed for DM, OM and NDF digestibility. Substituting BBP for barley grain up to 20% of the diet DM did not affect nutrient intake, growth performance and nutrient digestibility of kids and resulted in a decrease in feed cost.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.9
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• pp.1361-1366
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• 2008

One-hundred and twenty Ischia grey rabbits, traditionally raised in pits, were equally divided after weaning (32 days) into three groups: group C, housed in cages (4 rabbits/cage) and fed a commercial concentrate; group GF, housed as C group and fed grasses collected on the island and crushed faba beans supplemented with an appropriate mineral vitamin mix; group P, housed in pits (8 rabbits/pit) and fed as GF group. Feed intake was recorded daily and live weight monthly up to slaughter (92 days). At slaughter, 10 rabbits per group were used to measure carcass and meat traits. The carcasses were weighed and measured according to the standard procedures and meat samples from the Longissimus dorsi and left hind leg were analysed for water holding capacity and chemical composition, respectively. During the entire trial, group C consumed significantly (p<0.01) a higher quantity of feed than the other groups (126.1 vs. 63.4 and 66.5 g/d, resp. for groups C, GF and P) and at slaughter showed a significantly (p<0.01) higher body weight (2,529.7 vs. 1,324.4 and 1,375.4 g, resp. for groups C, GF and P). Significant differences (p<0.01) were found also for dressing out percentage (68.6 vs. 66.6 and 66.9%, resp. for groups C, GF and P) and for meat chemical composition, in particular lipid percentage (4.13 vs. 1.84 and 1.93%, resp., for groups C, GF and P, p<0.01) and moisture (73.7 vs. 76.4 and 76.3%, resp. for groups C, GF and P, p<0.01). The results suggest the opportunity to obtain heavier animals raised in the pits if their diets were integrated with commercial feed.

• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.1
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• pp.26-34
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• 2013

Durability performance in RC structures varies significantly with changes in cover depth and mix proportions. GGBFS (Ground Granulated Blast Furnace Slag) is very effective mineral admixture and widely used for an improved resistance to chloride attack. In this paper, characteristics such as porosity, compressive strength, and diffusion coefficient are evaluated in GGBFS concrete with 30~70% of replacement ratio and $4,000{\sim}8,000cm^2/g$ of fineness. Through the tests, more dense pore structure, higher compressive strength, and lower diffusion coefficient are obtained in GGBFS concrete, which are evaluated to be more dependent on replacement ratio than fineness. With increasing curing period from 3 to 91 days, porosity decreases to 77.47% and strength increases to 373% in GGBFS concrete. Chloride diffusion coefficient in GGBFS concrete decreases to 64.4% compared with that in OPC concrete, which shows significant improvement of durability performance.

• Journal of Digital Contents Society
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• v.14 no.1
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• pp.35-40
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• 2013

The use of slurry with a mix of abrasives and coolant for making Wire Saw in the photovoltaic industry has sharply increased with the semiconductor wafer. In this paper, the slurry was isolated, purified and dried by microwave drying method with high-purity silicon carbide powder obtained through chemical processing. Dried slurry bulk was first pulverized and chemical treatment was applied to produce powder. The produced slurry powder was then analyzed by going through the following analysis; thermal analysis, particle size analyses: SEM shots, elemental analysis, XRF and XRD. The results of this study found the recovery rate of the power obtained though the chemical processing to be higher than the one obtained from mineral processing. The results anticipate infrastructure building and active responses to increasingly stronger domestic and international environmental regulations through the integration and recycling of large amounts of slurry in the photovoltaic industry.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.75-81
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• 2010

In this study, when concrete properties are changed by concrete mix proportions or blending of admixtures, the characteristics of electro-chemical method for corrosion assessment of the embedded steel are compared and its causes are analyzed. According to the results, when the ratio of corroding area was less than 10%, the half-cell method was affected by concrete properties. In the case of specimen blended admixtures, it is possible to assess the high-corroded steel qualitatively using the half-cell method. For the polarization resistance method, though the corroding area was less than 10%, it has not affected by concrete properties. However, in case of specimen blended admixtures, the corrosion level of steel was underestimated than OPC specimens having a similar corroding area.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.5
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• pp.25-34
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• 2012

It has been well known that concrete structures exposed to acid and sulfate environments such as sewer etc. show significant decrease in their durability due to chemical attack. Such deleterious acid and sulfate attacks lead to expansion and cracking in concrete, and thus, eventually result in damage to cement mortar by forming expansive hydration products due to the reaction between cement hydration products and acid and sulfate ions. In this study, the effect of fly ash and blast furnace slag on the bond performances of structural synthetic fiber in latex modified cement mortar under sulfate environments. Fly ash and blast furnace slag contents ranging from 0 % to 20 % are used in the mix proportions. The latex modified cement mortar specimens were immersed in fresh water, 8 % sodium sulfate ($Na_2SO_4$) solutions for 28 and 50 days, respectively. Pullout tests are conducted to measure the bond performance of structural synthetic fiber from latex modified cement mortar after sulfate environments exposure. Test results are found that the incorporation of fly ash and blast furnace slag can effectively enhance the PVA fiber-latex modified cement mortar interfacial bond properties (bond behavior, bond strength and interface toughness) after sulfate environments exposure. The microstructural observation confirms the findings on the interface bond mechanism drawn from the fiber pullout test results under sulfate environments.

• Resources Recycling
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• v.30 no.5
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• pp.17-24
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• 2021

Natural aggregate regular exploitation has led to environmental and resource depletion issues; consequently, construction waste has become an important raw material in the supply of aggregate smoothly. The recycled aggregate produced in the most of recycled aggregate processing company in Korea has a high adhesion ratio of cement paste and mortar, which affects the water absorption ratio and density. Therefore, the quality of recycled aggregate needs to be improved. In this study, we improved the quality of recycled aggregate through the use of a multistage separation ball mill. This ball mill has a sieve which protects the ball mix and improves the motion. Products produced by using multistage separation ball mill were compared with various quality standard for utilization as recycle aggregate. Finally, we confirmed that the multistage separation ball mill can efficiently separate cement paste and mortar from natural aggregate and that it is suitable for the production of recycled aggregates.

• Economic and Environmental Geology
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• v.57 no.2
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• pp.219-231
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• 2024

A survey of concrete plants in Incheon Metropolitan City and Gyeonggi Province was used to conduct an analysis of aggregate transport distance and production forms, as well as to evaluate the features and current status of aggregates distribution. As a result, areas such as Incheon, Siheung, Bucheon, Gimpo, and Siheung, where the distance to the demand points is less than 20 km, exhibited bidirectional distribution whereas Paju, Yongin, Yangju, and Pocheon, with distances ranging from 20 to 50 km is showed a unidirectional distribution pattern supplying aggregates exclusively to Incheon. Survey on manufacturing forms, more than 85% of the gravel dispersed in the Incheon area is made up of crushed aggregates derived from rocks discharged at construction sites indicating a considerable skew in supply chain. These findings are predicted to have a detrimental influence on aggregate supply in the long run, necessitating policy changes targeted at building an optimal aggregate distribution market.

• Advances in nano research
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• v.16 no.3
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• pp.217-229
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• 2024

This paper presents results of visual analysis of cracks formation and propagation of concretes made of quaternary binders (QBC). A composition of the two most commonly used mineral additives, i.e. fly ash (FA) and silica fume (SF) in combination with nanosilica (nS), has been proposed as a partial replacement of the cement. The principal objective of the present study is to achieve information about the effect of simultaneous incorporation of three pozzolans as partial replacement to the OPC on the fracture processes in concretes made from quaternary binders (QBC). The modern and precise non-contact measurement method (NCMM) via digital image correlation (DIC) technique was used, during the studies. In the course of experiments it was established that the substitution of OPC with three pozzolans including the nanoadditive in FA+SF+nS FA+SF+nS combination causes a clear change of brittleness and behavior during fractures in QBCs. It was found that the shape of cracks in unmodified concrete was quasi-linear. Substitution of the binder by SCMs resulted in a slight heterogeneity of the structure of the QBC, including only SF and nS, and clear heterogeneity for concretes with the FA additive. In addition, as content of FA rises throughout each of QBC series, material becomes more ductile and shows less brittle failure. It means that an increase in the FA content in the concrete mix causes a significant change in fracture process in this composite in comparison to concrete with the addition of silica modifiers only.