• Magazine of the Korean Society of Agricultural Engineers
• /
• v.41 no.1
• /
• pp.97-105
• /
• 1999

Recently , polymer concrete has been widely used in the construction industry because of its quick setting, high strength, excellect adhesion, watertightness and chemical resistance compared to ordinary cement concrete. Its application is also increased. In this paper, lightweight polymer mortars using unsaturated polyester resin and lightweight aggregate are prepared with various mix proportations, and tested for slump working life, apparent specific gravity , flexural and compressive strengths. As a result, the slump and working life can be controlled and thier flexural and compressive strengths are 9.7 to 22.0 MPa , and 23.0 to 100.8 MPa respectively at apparent specific gravities of 0.86 to 1.73.

• Polymer(Korea)
• /
• v.32 no.4
• /
• pp.377-384
• /
• 2008

In this study, the microsphere silicone polymer beads were synthesized by UV irradiation and alkoxy hydrolysis. The coefficient of variation (CV) of microsphere silicone polymer beads were decreased with increasing UV intensity, reaction time. The mean particle diameter, refractive index, and pH value were $4.1{\mu}m$, 1.43 and 7.5, respectively. Also, the true and bulk specific gravity, moisture content were 1.30, and 0.40, below 2%. The mean particle diameter and CV were the lowest at 0.1 wt% hexamethyldisilazane (HMDS) and their roundnesses were $0.95{\sim}0.98{\mu}m$ values. The particle dispersion index of microsphere silicone polymer beads was 4.92 at 450 W, 90 min and the yield was increased to 11.3% at 20 wt% methyltrimethoxysilane (MTMS). The mean particle diameter was decreased with increasing the stirring rate and reaction temperature.

• Journal of the Korean Ceramic Society
• /
• v.13 no.1
• /
• pp.11-19
• /
• 1976

This study was focused on the improvement of production techniques of small crucibles in relation with the appropriate selection of raw materials, various batch compositions and physical and chemical characteristics of the crucibles. Various tests gave the optimum batch composition for the carbon bond graphite cructble as follows: Pyontaek graphite flake (refractory aggregate) : 40Part Silicon carbide: 15Part Tar pitch (binder) : 11Part Inorganic additives (to improve the oxidation resistance) : 15 Part Cryolite : 3 Part Ferro manganese : 2 Part Ferrosilicon : 25 Part Crucibles pressed with 400kg/$\textrm{cm}^2$ at 12$0^{\circ}C$. and fired in reducing atmosphere at 120$0^{\circ}C$ brought the most favorable results as follows: Bulk density : 2.31 Apparent density : 2.58 Porosity : 15.2% Oxidation loss at 1, 50$0^{\circ}C$. for 3 hrs : below 3.77% Water absorption : 6.01% Compressive strength : 438kg/$\textrm{cm}^2$ Tensile strength : 256kg/$\textrm{cm}^2$.

• Journal of Forest and Environmental Science
• /
• v.15 no.1
• /
• pp.98-106
• /
• 1999

This study was carried out to analyze the mechanical properties of soil for counterplan of recovery construction and the slope stability on fill slope of Sang-gul forest road in Mt. Gari. To analyze the mechanical properties of apparent soil on fill slope in forest road, various soils such as soil, gravelly sandy soil, weathered rock were used as experimental sample in this study. In each experimental sample, particle size distribution test, liquid limit test, plastic limit test, and specific gravity test were carried by Korean industrial standards(KS F 2302, KS F 2303, KS F 2304, KS F 2306, KS F 2308). Through the results of soil particle size distribution analysis, soil moisture content analysis, and specific gravity analysis, soil texture, uniformity coefficient, curvature coefficient, dry density and specific gravity were able to be determined in sampling site. As a results in this study, soil was classified as SP, SW, GP by Unified Soil Classification Standard (USCS). specific gravity and dry unit weight of soil have the value range of 2.52~2.60 and 1.39~1.43, respectively. Also plastic index showed non plastic condition.

• Journal of the Korean Ceramic Society
• /
• v.39 no.9
• /
• pp.857-862
• /
• 2002

Porous ceramic supports with immobilized microorganisms for the water purifier were synthesized by firing green compacts of mixed powder comprising of fly ash, bentonite and an additive of yeast powder at 800∼1,000$^{\circ}C$ for 1h and the pore and mechanical properties of specimens were investigated. The compressive strength was increased in FB (Fly Ash + Bentonite) specimens while pore properties was decreased with increasing the bentonite content and sintering temperature. The compressive strength, bulk density, apparent density, porosity, mean pore size, pore volume and specific surface area of FB specimens at 800∼1,000$^{\circ}C$ were 89.6∼128.9 kgf/$cm^2$, 1.25∼1.43, 1.61∼1.78, 27.2∼62.2%, 7.9∼25.6 ${\mu}m$, 8.9∼$22.2{\times}10^{-5}\;cm^3/g$ and 35.2∼134.3 $m^2/g$, respectively. The pore properties of FBY (FB+yeast powder) specimens were superior to that of FB specimens, however compressive strength was decreased with increasing yeast powder content. The overall properties of 9F1B1Y (9F1B+10% of yeast powder) specimens at 900$^{\circ}C$ for 1 h were 98.7 kgf/$cm^2$, 1.20, 1.67, 68.1%, 48.9 ${\mu}m$, $29.5{\times}10^{-5}\;cm^3/g$ and 152.2 $m^2/g$, respectively. In this study, it was revealed that 9F1B1Y specimen demonstrated better S. saprophyticus adherence properties n their surface pores. Consequently, the microorganisms immobilized on porous ceramic supports showed better water purifying performance with many pores and adequate strength.

• Journal of the Korea Institute of Building Construction
• /
• v.17 no.6
• /
• pp.493-498
• /
• 2017

This study is a pioneer investigation to enhance the insulation capacity of the conventional aerated concrete using hydrophobic aerogels. As the main test parameters, aerogel content varied from 0% to 40% of the foam volume. Test results showed that the compressive strength of aerated concrete containing aerogels was lower by 17%~34% than that of the conventional aerated concrete. In addition, the effect of the aerogels on reducing thermal conductivity of aerated concrete is insignificant because of the partial condensation and abnormal distribution of the hydrophobic aerogels. Hence, further hydrophilic treatment for the surface of aerogels is recommended to minimize the decrease in compressive strength and enhance the insulation capacity of aerated concrete.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.12 no.1
• /
• pp.56-61
• /
• 2002

Porous clay ceramics was fabricated using the surfactant as a foaming agent in the secondary-clay produced at Young-Am area in Chun-Nam province. The concentration of surfactant in ceramic slurry was the key factor controlling the pore characteristics and physical properties of the porous ceramics. The more increase of the surfactant concentration increase the more foaming ability and the stability of foamed layer were improved, but the foaming ability was limited within 6.0 wt% of surfactant because the initial viscosity of the slurry increased with increasing the amounts of surfactant. The formed specimen were sintered at both $1150^{\circ}C$ and $1200^{\circ}C$, the porous ceramics showed 0.9 of specific gravity, 50% of water absorption, 45% of apparent porosity, 14% of shrinkage and 70 kg/$\textrm{cm}^2$ of compressive strength.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.18 no.6
• /
• pp.258-263
• /
• 2008

The fine aggregates of below 2 mm size was fabricated using by the vertical furnace in which the aggregates could be sintered at floating state and its physical properties were analyzed. The liquid formed at the surface of specimens sintered at $1200{\sim}l300^{\circ}C$ induced a gas in core to expand so the denser shell and porous core could be produced. The C series specimen fabricated by crushing an extruded body had an irregular shape and sharp edges but those became spheroidized by bloating due to gas expansion inside. The fine aggregates fabricated in this study was as light as floating in the water and had an apparent density of $0.68{\sim}1.08$. The absorption rate was proportioned to a porosity showing that the pores in core was not closed completely. The properties of fine aggregates fabricated in vertical furnace were similar with those of in an electric muffle furnace but the sticking-together phenomenon by surface fusion was not occurred in the vertical furnace. The aggregates fabricated in this study had a little lower impact resistance than that of natural aggregate but satisfied the unit volume weight standard specified in KS.

• Magazine of the Korea Concrete Institute
• /
• v.6 no.5
• /
• pp.158-170
• /
• 1994

The results of an experimental study on the manufacture and the mechanical properties of carbon fiber rekforced silica fume . cement composites and light weight fly ash . cement composites are presented in this paper. 11s the test results show, the flexural strength, fracture toughness and ductility of CF reinforced silica fume . cement composites were remarkably increased by the increase of carbon fiber contents. And the workability of the fly ash . cement composites were improved, but the compressive and flexural strength and bulk specific gravity of them are decreased by increasing the ratio of fly ash to cement. And the compressive and flexural strength of the fly ash cement composites by cured under the hot water were improved than those by mositure cured. Also, the manufacturing process technology of lightweight fly ash . cement composites in replacement of general autoclaved lightweight concrete was developed and its optimum mix proportions were proposed.

• Resources Recycling
• /
• v.24 no.3
• /
• pp.66-75
• /
• 2015

The flexural performance of amorphous steel fibers having environmental and economy benefits due to relatively short manufacturing process were evaluated as well as that of hooked steel fibers by varing fiber length and volume fraction. Fiber lengths were 10 mm, 20 mm, 30 mm and fiber volume fractions were varied from 0.3% to 1.2%. Test results with flexural performance showed that mixing design needs to be careful because of relatively high volume of amorphous steel fiber compared to hooked steel fibers. High flexural strength was obtained from both longer fiber length and higher volume fraction. Residual strength and toughness of amorphous steel fiber were similar to that of hooked steel fiber, even though rapid dropping of applied load right after concrete matrix breaking. It can be judged that relatively high ability of energy dissipation around first cracking area relatively overcome rapid dropping of loading.