• Journal of Industrial Technology
• /
• v.16
• /
• pp.39-44
• /
• 1996

The waste basalt might be recycled in concrete, resulting in energy saving and environmental protection. An half Factorial Experiments were performed with the variables of W/C ratio, S/A, Crushed stone/Basalt ratio and Slump as a preliminary study for optimum mix design of concrete. The results show that the W/C ratio is the most important factor to the concrete strength. The substitute of waste basalt up to 100% has little influence, saying that it can substitute the coarse aggregate without damaging the concrete properties.

• Journal of Ocean Engineering and Technology
• /
• v.18 no.1
• /
• pp.53-62
• /
• 2004

The Purpose of this study is to recycle the waste concrete, which is generated in huge quantities, from construction works. in order to achieve this goal, it is important to determine the compressive strength, workability, slump, and ultrasonic velocity of recycled aggregate concrete. Thus, several experiment parameters are considered, such as water-cement ratios, sand percentage, and fine aggregate composition ratios, in order to apply the recycled aggregate concrete to pre-cast artificial fishing reefs. From the results, it has been shown that the proper mix designs for reef concrete are W/C=45%, S/a=50%, SR50:SN50 in recycled sand and natural sand mix combination case, W/C=45%, S/a=50%, SC50:SN50 in crushed sand and natural sand mix combination case, W/C=45%, S/a=50%, SR50:SC50 in recycled sand and crushd sand mix combination case. Also, this study shows that the shape and surface roughness of fine aggregate particles have an effect on the strength, slump, ultrasonic velocity of tested concrete, and the compressive strength ratios of 7days' and 90days' curing ages of recycled aggregate concrete are about 70% and 110% of 28days' curing age.

• Journal of the Regional Association of Architectural Institute of Korea
• /
• v.20 no.6
• /
• pp.17-23
• /
• 2018

The purpose of this study is to suggest 100MPa class ultra high strength concrete mix design model applying neural network theory, in order to minimize an effort wasted by trials and errors method until now. Mix design model was applied to each of the 70 data using binary binder, ternary binder and quaternary binder. Then being repeatedly applied to back-propagation algorithm in neural network model, optimized connection weight was gained. The completed mix design model was proved, by analyzing and comparing to value predicted from mix design model and value measured from actual compressive strength test. According to the results of this study, more accurate value could be gained through the mix design model, if error rate decreases with the test condition and environment. Also if content of water and binder, slump flow, and air content of concrete apply to mix design model, more accurate and resonable mix design could be gained.

• Journal of the Korea Concrete Institute
• /
• v.21 no.2
• /
• pp.179-186
• /
• 2009

The peculiarity pointed out for high strength concrete is the occurrence of spalling during a fire. Recently, there are many efforts such as development of all types of spalling reducing materials and other innovative materials in various fields. Need is now to examine the adequate mixing proportions of these materials. This study intended to derive experimentally and statistically mix proportions that can represent the basic quality requirements as well as the optimal effects on the fire-resistance for 4 types of functional materials that are metakaolin, waste tire chip, polypropylene fiber and steel fiber. Here, the tests were planned through an optimal test method using an orthogonal array table with 4 parameters and 3 levels. The statistical analysis adopted the response surface analysis method. Results verified mutual complementary contribution between the materials when using a combination of the functional materials selected as parameters for the strengthening of the fire-resistance of 80 MPa-class high strength concrete. Besides, the optimal conditions of the fire-resistance strengthening materials derived through response surface analysis were a volumetric replacement of silica fume by 80% of metakaolin, a volumetric replacement of fine aggregates by 3% of tire waste chip, and an addition of 0.2% of the whole volume by polypropylene fiber without mixing of steel fiber. In such cases, the basic characteristics as well as the fire-resistant characteristics of high strength concrete were also satisfied.

• Journal of the Korea Concrete Institute
• /
• v.21 no.1
• /
• pp.3-11
• /
• 2009

The increased demand and consumption of coal has intensified problems associated with disposal of solid waste generated in utilization of coal. Major utilization of coal by-products has been in construction-related applications. Since fly ash accounts for the part of the production of utility waste, the majority of scientific investigations have focused on its utilization in a multitude of use, while little attention has been directed to the use of bottom ash. As a consequence of this neglect, a large amount of bottom ash has been stockpiled. However, the need to obtain safe and economical solution for its proper utilization has been more urgent. The study presented herein is designed to ascertain the performance characteristics of bottom ash, as autoclaved lightweight foamed concrete product. The laboratory test results indicated that tobermorite was generated when bottom ash was used as materials for hydro-thermal reaction. According to the analysis of variance, at the fresh state, water ratio affects on flow and slurry density of autoclaved lightweight foamed concrete, but foam ratio influences on slurry density, while, at the hardened state, foam ratio affects on the density of dry and the compressive strength but doesn't affect on flexural and tensile strength. In the results of response surface analysis, to obtain target performance, the most suitable mix condition for lightweight foamed concrete using bottom ash was water ratio of 70$\sim$80% and foaming ratio of 90$\sim$100%.

• Nuclear Engineering and Technology
• /
• v.2 no.3
• /
• pp.149-161
• /
• 1970

This paper describes a detailed investigational performance on the gamma radiation shield effect of heavy concretes that were manufactured by the use of mineral ores produced domestically and which may be possibly applied for the biological shield design. Ten different kinds of mineral ores were collected for use as the aggregates, physical test and chemical analysis for them were carried out to select the aggregate with a better property. Through the experimental investigation on the shielding effect of various concretes with different combination of concrete components such as water-cement and fine-coarse aggregate ratios, it was possible to derive some criteria for the best condition being capable of obtaining the concretes with high density and good uniformity. Data on the shielding-effectiveness of the different concretes were obtained by performing collimated beam experiment using 60Co gamma-ray. Analyzing the shielding-efficiency, shielding-concrete specific gravity and biological shield cost, the optimum condition of yielding the best economic shielding design, with low cost and good spatial distribution to some extent was determined.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.11 no.1
• /
• pp.48-54
• /
• 2023

In this research, The basic physical properties and EMP shielding performance by thickness were evaluated for optimum composition of EMP shield concrete that can be applied on-site by mixing carbon-based materials with high conductivity into concrete that uses electric furnace oxidized slag (EOS). As a result of the evaluation, it was confirmed that the slump decreased as the amount of mixed carbon fib er (CF) increased, and increased when milled carb on (MCF) was mixed. As for the compressive strength, it was confirmed that EOS enhanced the strength compared to NA, and it was confirmed that the strength decreased when CF and MCF were mixed. As the thickness of the EMP shielding measurement increases, the shielding rate increases, and it was confirmed that the type of conductive material and the thickness of the test specimen have a greater influence on the shielding rate than the Amount of conductive material added. As a result of a comparative evaluation, EOS CF 0.2 is considered suitable for EMP shield concrete formulation.

• Journal of the Korea Concrete Institute
• /
• v.16 no.6 s.84
• /
• pp.751-757
• /
• 2004

Artificial lightweight aggregates and solids were manufactured with coal ash(fly ash, bottom ash). In order to apply alkali-activated coal ash(fly ash, bottom ash) artificial lightweight aggregate to concrete, several experimental studies were performed. Thus, it can be noticed the optimal mix proportion, basic characteristies, mechanical properties and environmental safety of alkali-activated coal ash(fly ash, bottom ash) solid and alkali-activated coal ash(fly ash, bottom ash) artificial lightweight aggregate. Also, the freezing-thawing test property of concrete using the alkali-activated coal ash(fly ash, bottom ash) artificial lightweight aggregate was investigated. As a result, the optimal mixing proportion of coal ash(fly ash, bottom ash) solid to make alkali-activated artificial lightweight aggregates was cement $10\%$, water glass $15\%$, NaOH $10\%$, $MnO_2\;5\%$. Alkali-activated coal ash(fly ash, bottom ash) solid can achieve compressive strength of 36.4 MPa, at 7-days, after the paste was cured at air curing after moist curing during 24 hours in $50^{\circ}C$. Alkali-activated coal ash(fly ash, bottom ash) artificial lightweight aggregate that do impregnation to polymer was improved $10\%$ crushing strength $150\%$, and was available to concrete.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.10a
• /
• pp.671-676
• /
• 2000

This study was to determine the technical feasibility of using wastepaper fibers, obtained through dry processing of wastepaper, as reinforcement in thin cement produces. Dry-processed waste papers have high levels of noncellulosic impurities, and the recycling process also breads and damages the fibers. To produce wastepaper fiber-cement composites, first the influential variables in the slurry-dewatering method of processing the composites were identified in an experimental study based on factorial design. Among the proportioning and processing variables investigated, fiber mass fraction and level of substitution of virgin fibers with recycled ones were found to have statistically significant effects on mechanical and physical properties of composites. Subsequently, response surface analysis techniques were used to devise an experimental program that helped determine the optimum combinations of the selected influential variables based on mechanical and physical properties, and cost.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.515-516
• /
• 2009

Recently, A lot of roads, railroads and tunnels are constructed for development of industrialization and efficient use of national land. So, we have focused on to figure out the best combination between Slag powder and Mortars with Accelerator to repair of tunnel structure.