• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05b
• /
• pp.401-404
• /
• 2006

Much of requirements to the civil and building structures have been changed in accordance with the social and economic progress. Ductility of high performance fiber reinforced cementitious composites(HPFRCCs), which exhibit strain hardening and multiple crackling characteristics under the uniaxial tensile stress is drastically improved. In HPFRCC application, PVA fiber has been dominantly used as a reinforcement because of its excellent alkali resistant nature as well as high strength. But the inherent strong hydrophilicity of PVA fiber promotes the moisture absorption in cement matrix and thus it may cause the corrosion of steel structure. Therefore, it is necessary to control the interfacial adhesion of cement composites. In present study, to control the interfacial adhesion of the cementitious composites reinforced by PVA fiber, UV irradiation of the PVA fiber were performed and their effects on the adhesion property and general characteristics were investigated extensively.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05b
• /
• pp.277-280
• /
• 2006

This paper presents the findings on the sulfate resistance of mortar specimens with or without alkali-free accelerator exposed to sodium sulfate solution for 270 days. Test results confirms a negative effect of alkali-free accelerator on the sulfate deterioration. Additionally, the influences of exposure concentration and temperature of sulfate solution on expansion were investigated. Especially, at a high concentration of solution a significant expansion of mortar specimens with alkali-free accelerator was observed. Further, low temperature also promoted the deterioration of the cement system due to sulfate attack.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05b
• /
• pp.453-456
• /
• 2006

If cement can be manufactured with industrial byproducts such as granulated blast furnace slag(GBFS), phosphogypsum(PG), and waste lime(WL) instead of clinker as its counterproposal, there would be many advantages, including maximum use of these industrial byproducts for high value-added resources, conservation of natural resources and energy by omitting the use of clinker, minimized environmental pollution problems caused by CO2 discharge, and reduction of the production cost. This research investigates the chloride ion permeability of NSC concrete added PG and WL to GBFS as sulfate and alkali activators. The result of experiment of chloride ion permeability, showed that NSC is very excellent in seawater resistance. Such a reasons are that the hydrate like CSH gel and ettringite formed dense pore structure of NSC matrix.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05b
• /
• pp.213-216
• /
• 2006

As form a part of way to improve the durability of concrete placed on deleterious environments such as acidic rivers, sewage wastewater, and sewer system, the paper presented here is the results of experimental immersion test, and for the test solution, 4 types sulfuric acid solution was prepared. From the result of EDS analysis of cement paste at 180 days of immersion, the detected major chemical elements were Ca and S and they are assumed as composing elements of gypsum. A comparative study between prediction models from the Japanese Standard and the present study corresponding to $d=C\sqrt{t}$ and $d=\alpha{\cdot}t^n$ respectively accorded well with each other, as being 0.98 of determination coefficient.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.11a
• /
• pp.74-77
• /
• 2003

This paper investigated the apparent chloride diffusivity of various concretes. Ten mixtures of concrete were initially prepared and tested to estimate diffusion property. The penetration depth and concentration of chloride ion were examined at the same water-binder ration. The binders were composed of normal portland cement, fly ash, ground granulated blast-furnace slag, and silica fume. From the results, it was concluded that using the mineral admixtures had a filling effect on the pore structure of cements matrix due to those pozzoanic reaction with the hydrates of cement, which increases the tortuosity of pore and makes large pore finer. And diffusivity of chloride is following: NPC100 > F10N90 > F30N70 > F20N80 > F20S05 > G30N70 > F10S05 > G30S05 > G30F15 > G50N50.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.03a
• /
• pp.1390-1395
• /
• 2005

To analyze the effects of oyster shell particles, inserted in the self-hardening matrix such as cement paste, on strength, homogenization analysis using micro structure was used to estimate and assess the apparent elastic modulus of oyster shell particle. DIB modeling technique was used to represent of the micro structure of oyster shell mixed concrete. The results showed that the apparent elastic modulus of LOS (large oyster shell particle) was changed with the amount of LOS inserted. In particular, when the amount of LOS was 200% of the weight of cement, the apparent elastic modulus of LOS tended to decrease rapidly. This could mean that the strength of oyster shell mixed concrete is much affected by LOS inserted material in mixed ratio of 200%.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1997.10a
• /
• pp.339-344
• /
• 1997

During recent years the durability of concrete structures has attracted considerable interest in concrete practice, material research and long-term deformation. To preserve the brittleness of concrete as well as energy absorption and impact resistance, amount of fiber usage has greatly increased year to year in the field of public works. When fly ash, fine powder, mixed into concrete, it condensed the void of concrete structure. Expecially, there's a great effect for strength improvement of concrete by initial pozzolanic reactions. Pozzolan reaction, between cement particle and fly ash, can elaborate the micro structure of matrix. So it was able to improve the effect of fiber reinforced by increased adhesion between cement paste and steel fiber. And so, in this paper, we dealt SFRC for the purpose of efficiently using of industrial by-products and its economical manufacturing. Also we performed the test for durability such as chemical resistance, freeze-thaw resistance and accelerated carbonation of SFRC using fly ash.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.05b
• /
• pp.205-208
• /
• 2005

The present study surveys the concrete properties-concerned factors influencing the chloride threshold level for steel corrosion in concrete, altogether with supporting experimental works, in particular, chloride binding capacity, buffering capacity, condition of steel-concrete interface and cement replacement. It concluded that the order of the dominance on CTL is such that chloride binding < buffering capacity of cement matrix < physical condition of steel-concrete interface. This is attributed to the fact that calcium hydroxide does not form a continuous layer on the steel surface and that bound chlorides are released at the stage of corrosion initiation.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2018.11a
• /
• pp.165-166
• /
• 2018

Researches for the development of renewable energy as a fuel substitute for global warming and depletion of petroleum resources are actively being carried out. Among them, the annual growth rate of PV generation is 20.73%, which is higher than other renewable energy sources. However, the production of 1 ton of polysilicon, which is known as a raw material for solar power generation panels, generates 2 tons of waste. As the demand for PV panels increases, the problem of the treatment of polysilicon sludge is attracting attention, and studies on the utilization of polysilicon sludge are needed. Therefore, in this study, the applicability of polysilicon sludge treated as industrial waste to the lightweight panel for architectural purposes was examined.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2009.11a
• /
• pp.77-80
• /
• 2009

Because buildings which apply color that is various to concrete recently are introduced, value as design element of building is rising gradually in townscape. Even if expense is increased according as importance of concrete that have variety of design because do such social background and connection is emphasized, development of color concrete is pressing. Therefore, in this research, examined concrete physical & chemical characteristics by use of acid agent as part of research to embody diverse surface color of cement material. Here, embodiment of various color by unique color that stained hydrate has as that Color Concrete forms stained oxide that react with hydrate within concrete spreading stained agent that contain acid and metallic-ion in matrix that have cement ingredient on the surface is available.