• Journal of the Korean Ceramic Society
• /
• v.40 no.7
• /
• pp.696-701
• /
• 2003

The grinding efficiencies of silica powder in a small scale stirred ball mill were investigated by energy consumption estimate. Comparing with a non-treated silica powder and a heating treated silica powder, it was found that a silica powder cooled in room temperature after heating treatment at 600∼900$^{\circ}C$ consumed lower grinding energy than non-treated silica powder, and a silica powder quenched after heating treatment consumed lower grinding energies about 52∼62%, in case of dry grinding. Additionally, if heating treated silica powder grind in wet method, energy consumption will be decreased about 40% than in dry grinding, and the dependency of the particle size to the grinding efficiency, quenching significantly improved it.

• Korean Journal of Materials Research
• /
• v.24 no.5
• /
• pp.271-276
• /
• 2014

Silica nano-powder (SNP) is an inorganic material able to provide high-performance in various fields because of its multiple functions. Methods used to synthesize high purity SNP, include crushing silica minerals, vapor reaction of silica chloride, and a sol-gel process using TEOS and sodium silicate solution. The sol-gel process is the cheapest method for synthesis of SNP, and was used in this study. First, we investigated the shape and the size of the silica-powder particles in relation to the variation of HCl and sodium silicate concentrations. After drying, the shape of nano-silica powder differed in relation to variations in the HCl concentration. As the pH of the solution increased, so did the density of crosslinking. Initially, there was NaCl in the SNP. To increase its purity, we adopted a washing process that included centrifugation and filtration. After washing, the last of the NaCl was removed using DI water, leaving only amorphous silica powder. The purity of nano-silica powder synthesized using sodium silicate was over 99.6%.

• Advances in concrete construction
• /
• v.11 no.3
• /
• pp.239-253
• /
• 2021

The behavior of concrete containing waste glass as a replacement of cement or aggregate was studied previously in the most of researches, but the present investigation focuses on the recycling of waste glass powder as a substitute for silica fume in high strength concrete (HSC). This endeavor deals with the efficiency of using waste glass powder, as an alternative for silica fume, in the flexural capacity of HSC beam. Thirteen members with dimensions of 0.3 m width, 0.15 m depth and 0.9 m span length were utilized in this work. A comparison study was performed considering HSC members and hybrid beams fabricated by HSC and conventional normal concrete (CC). In addition to the experiments on the influence of glass powder on flexural behavior, numerical analysis was implemented using nonlinear finite element approach to simulate the structural performance of the beams. Same constitutive relationships were selected to model the behavior of HSC with waste glass powder or silica fume to show the matching between the modeling outputs for beams made with these powders. The results showed that the loading capacity and ductility index of the HSC beams with waste glass powder demonstrated enhancing ultimate load and ductility compared with those of HSC specimens with silica fume. The study deduced that the recycled waste glass powder is a good alternative to the pozzolanic powder of silica fume.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2015.11a
• /
• pp.9-10
• /
• 2015

Waste Concrete Powder will be generated during the manufacture of construction waste as recycled aggregate Waste concrete. The main component of the waste concrete Powder is a silica-based composition 51% SiO₂, waste concrete cement-based composition Al₂O₃ 10%, CaO 26% component are contained. The material is silica sand of PHC piles should experiment by replacing the Waste Concrete Powder. The compressive strength results are as follows. 25% when the Silica was replaced 32.5Mpa, when 50% have replaced 43.4Mpa, when 75% have replaced 45.3Mpa was measured. Compared with the non-replaced test sample it appears that the strength increases. Therefore, it is determined that the practical use of the PHC piles by replacing silica via this experiment is possible.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2017.05a
• /
• pp.13-14
• /
• 2017

In this paper, research for use possibility as silica source of waste concrete powder discharged from direct and indirect carbonation has progressed. For the research, properties on the extruding panel using waste concrete powder with high silica content is evaluated. As the results, compressive strength of specimen is increased 24% compared to control specimen when waste concrete powder replaced 50%, that is discharged from carbonation process, as silica source.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.8 no.1
• /
• pp.131-137
• /
• 1998

A composite copper coated powder was generated by pressure hydrogen stripping copper from Kelex 100 solvent extractant in the presence of silica powder. Within the limitation of solvent extraction under constant conditions, both loading level and stripping rate were reproducible. The stripping copper kinetics are reduced from a divalent state to a metallic state and then deposited on the surface of the silica powder. Copper nucleates heterogeneously on the seed particles. They are giving an agglomerated and non - uniform powder.

• Journal of the Korean Ceramic Society
• /
• v.23 no.2
• /
• pp.31-37
• /
• 1986

The effect of dehydration temperature on the reduction process of silica-coated hematite was invest-igated The particle shape and magnetic properties of the products reduced from hematite at various conditions and the oxidation resistance of silica-coated iron powder were examined. It was revealed that single phase iron powder obtained over 45$0^{\circ}C$ had good magnetic properties. The iron powder manufactured between 45$0^{\circ}C$ and 50$0^{\circ}C$ displayed the maximum coercive force as a result of maintaining its acicular shaped. However the coercive force of iron powder reduced over 50$0^{\circ}C$ was decreased. The oxidation resistance of silica-coated iron powder in air was very good up to 11$0^{\circ}C$ and for 12 days.

• Journal of Ceramic Processing Research
• /
• v.13 no.spc1
• /
• pp.145-148
• /
• 2012

Spherical silica aerogel powders were fabricated via an emulsion polymerization method from a water glass. A water-in-oil emulsion, in which droplets of a silicic acid solution are emulsified with span 80 (surfactant) in n-hexane, was produced by a high power homogenizer. After gelation, the surface of the spherical silica hydrogels was modified using a TMCS (trimethylchlorosilane)/n-hexane solution followed by solvent exchange from water to n-hexane. Hydrophobic silica wet gel droplets were dried at 80 ℃ under ambient pressure. A perfect spherical silica aerogel powder between1 to 12 ㎛ in diameter was obtained and its size can be controlled by mixing speed. The tapping density, pore volume, and BET surface area of the silica aerogel powder were approximately 0.08 g·cm-3, 3.5 ㎤·g-1 and 742 ㎡·g-1, respectively.

• Korean Journal of Materials Research
• /
• v.16 no.6
• /
• pp.355-359
• /
• 2006

Fine silica powders were synthesized via w/o emulsion method using sodium silicate, ammonium sulfate, Triton N-57, and cyclohexane as silica source, precipitating agent, surfactant, and oil phase, respectively. The powders were prepared under a conventional process and an ultrasonic process using the same reactants at room temperature for 1 hr varying the concentration of $Na_2SiO_3$ solution and the mol ratio of $H_2O$/surfactant, respectively. The particle size of the silica powder was reduced with decreasing the concentration of sodium silicate solution and with increasing the mol ratio of $H_2O$/surfactant under with and without ultrasounds. The size of powder with ultrasounds was smaller than that without ultrasounds, which indicates that the application of ultrasound in the synthesis of silica powder is an efficient way to reduce particle size.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2006.05a
• /
• pp.115-118
• /
• 2006

Nowadays the using of concrete is generalized, and construction material is demanded to be lightweight according to increasing the height and capacity of buildings. Therefore, it needs to develop the products having the great quality and various performance. Extruding concrete panel made of cement, silica source, and fiber, and it is a good lightweight concrete material in durability and thermostable. The silica of important ingredient is natural material with hish SiO2 contents and difficult in supply because of conservation of environment. On the other hand, the stone powder sludge discharged about 20-30% at making process of crushed fine aggregate and it is wasted. The stone powder sludge is valuable instead of silica ole because the stone powder sludge includes water of about 20-60%, SiO2 of about 64% and it has fine particles. This experiment is on the properties of extruding concrete panel using the stone powder sludge use instead of silica. From this experiment, we find that it is possible to replace the silica as stone power sludge up to 50%,