• Advances in concrete construction
• /
• v.1 no.2
• /
• pp.151-162
• /
• 2013

The performance characteristics of high-strength and high-performance concrete are discussed in this review. Recent developments in the field of high-performance concrete marked a giant step forward in high-tech construction materials with enhanced durability, high compressive strength and high modulus of elasticity particularly for industrial applications. There is a growing awareness that specifications requiring high compressive strength make sense only when there are specific strength design advantages. HPC today employs blended cements that include silica fume, fly ash and ground granulated blast-furnace slag. In typical formulations, these cementitious materials can exceed 25% of the total cement by weight. Silica fume contributes to strength and durability; and fly ash and slag cement to better finish, decreased permeability, and increased resistance to chemical attack. The influences of various mineral admixtures such as fly ash, silica fume, micro silica, slag etc. on the performance of high-strength concrete are discussed.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.05a
• /
• pp.196-199
• /
• 2004

Metakaolin is a cementitious material for producing high-strength concrete. This material is now used as substitute for silica-fume. In this paper, we tested the compressive strength of concrete according to the substitute ratio of metakaolin, silica-fume. And we did the durability test such as chloride ion diffusion and chemical attack. In the compressive strength test, the result shows that $10\%$ substitute of metakaolin & silica-fume for binder is optimum. In the chloride ion diffusion test, according to the increase of substitute of metakaolin & silica-fume for binder, the diffusion coefficient is more reduced. And in the chemical attack test, according to the increase of substitute, the resistance is more excellent. In the durability test, we recognized that metakaolin is able to used as a substitute for silica-fume.

• International Journal of Concrete Structures and Materials
• /
• v.5 no.2
• /
• pp.119-123
• /
• 2011

Presented in the paper are findings of a project that examined the effect of slag grade and cement source on the performance of concrete mixtures. Slag cement contents were 20, 40, and 60 percent of the total cementitious material content. Two grades of slag cement were examined (Gr. 100 and Gr. 120) along with two sources of Type I cement. Compressive strength, durability, and permeability were measured. The results showed that the cement source affected the early age strength of the mixtures. At 28 days of age, mixtures containing Gr. 120 slag cement had higher compressive strengths than mixtures containing Gr. 100 slag cement, but by 90 days of age, the trend reversed. As for the chloride ion penetrability, mixtures cast with Gr. 100 slag cement passed fewer coulombs at 28 and 90 days of age than similar mixtures containing Gr. 120 slag. Mixtures containing Gr. 120 slag had the greatest durability factors.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.13 no.4
• /
• pp.79-86
• /
• 2004

Tooth errors inevitable in the manufacturing process have large effect on the strength/durability and vibration performances of gear drives. We show that the manufacturing errors affect the overall gear performances, especially vibration performance, and propose a robust optimal design method for gear dimension and its tooth flank form that guarantees reliable performances to the variation of manufacturing errors. This method begins with a search of optimal design candidates by using the previously developed gear optimal design method for the strength/durability and vibration performances. Then, the statistical analysis method is applied to find a robust design solution for the vibration performance which is generally very sensitive to the manufacturing variations.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.11a
• /
• pp.467-470
• /
• 2005

This study reports the properties of high early strength & durability of concrete using PC admixture. To apply these data to construction site, we did the lab tests. The target of this study is to accomplish early strength of concrete(5.0 MPa/18 hr), and we did the durability tests such as length change test, chloride ion penetration test, adiabatic test, etc. PC type was more excellent than PNS type admixture. According to these tests, we concluded that we can apply this type of PC admixture to the civil & construction site, and we can reduce the term of works and finally we can accomplish the economical construction.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05b
• /
• pp.5-8
• /
• 2006

In this study, various fundamental experiments including durability and time-dependent deformation are performed to compile a database for a utilization of high-strength concrete for PSC bridges. In the mix design, concrete strength at early age when prestressing forces are introduced to the PSC member and slumpflow suitable for pumping of concrete are considered to make a concrete fit for PSC bridges. The main parameters investigated are the kinds and replacement ratios of mineral admixtures and low-heat cement. Experimental tests on durability include penetration of chloride ions, freezing-thawing, combined deterioration, and simple adiabatic temperature rise test. In addition, time-dependent deformation such as creep, drying and autogenous shrinkage, which is particularly important factor in the design and construction of PSC bridges, is tested and analyzed.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.13 no.3
• /
• pp.103-110
• /
• 2014

In this study, spur and helical box models of an existing machine tool are investigated using structural and fatigue analyses. As the helical box model is shown to have less stress and deformation than those characteristics of the spur box model, the helical box has more strength and more transmission efficiency on the structure. In terms of fatigue analysis, the helical box model has more repeated fatigue strength than that of the spur box model. These study results can be effectively utilized in the design of real gear boxes of machine tools by anticipating and investigating prevention and durability against damage.

• International Journal of Concrete Structures and Materials
• /
• v.8 no.3
• /
• pp.259-268
• /
• 2014

This paper presents results of an experimental study which investigates the effect of industrial pozzolan made from calcined silt of dam at $750^{\circ}C$ for 5 h, on mechanical properties and durability of ordinary mortar, compared to the silica fume. Mortar specimens prepared with 5, 10 and 15 % of calcined silt to substitute cement were evaluated for their compressive and flexural strength, sulfate, acid and penetration of chloride ions resistance. The results were compared with ordinary mortar (without addition) and mortar containing 10 % of silica fume. The results obtained showed that the calcined silt of dam has a high potential to be used as a pozzolanic material, it improves the strength and the durability of mortar and compete the silica fume.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.21 no.1
• /
• pp.137-144
• /
• 2013

This study analyzes structural analysis with fatigue and natural frequency on ATV knuckle. The maximum equivalent stresses are happened at the end of knuckle in case of model 1, 2 and 3. As these stresses are below the allowable stress, these models can be stable structurally. The fatigue damage possibility at model 1 becomes more than model 2 and 3. Model 2 or 3 has more durability than model 1 at fatigue. As the resonances are happened at the frequency more than 2000 Hz in case of model 1, 2 and 3, there is no resonance possibilities at real driving. Prevention against damage and durability prediction on automotive chassis parts can be effectively improved by applying this study result on knuckle and improving structural strength.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2018.05a
• /
• pp.259-260
• /
• 2018

This study evaluated the compressive strength, freeze-thaw and sulfate resistance characteristics of concrete using CFBC-Ash. The CFBC-Ash was adjusted to a particle size of 75 ㎛ or less and using by increasing the fineness of powder through milling. As a result, it was confirmed that the concrete using CFBC-Ash shows a high compressive strength, durability. Also, it is confirmed that CFBC-ash can be used as a concrete binder.