• Magazine of the Korea Concrete Institute
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• v.6 no.3
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• pp.190-200
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• 1994

The purpose of this research is to examine experimentally the mechanical properties and economics of No-fines concrete for its application to the low-rise housing construction. Basic mechanical properties of No fines concrete are studied by measuring of compressive, tensile strength and stress-strain relationship, and economics of it is compared with other materials in unit cost and wall construction cost. From the test results, it can be concluded that No-fines concrete has advantages of good workability, light weight and lower construction cost, even though it has lower strength and modulus of elasticity than normal conc:rt:te does.

• Journal of the Korea Institute of Building Construction
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• v.18 no.3
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• pp.211-218
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• 2018

This study examined the reliability and revision necessity of concrete standard specifications based on the comparisons with test data obtained by using domestic artificial lightweight aggregates and the contents specified in different foreign specifications including ACI 211.2, ACI 213, ACI 301, JASS 5 and CEB-FIP. To achieve the continuous particle distribution of domestic fine lightweight aggregates, the partial addition of natural sand with the maximum size of 2.5mm was required. To control the segregation and excessive bleeding in the fresh lightweight concrete, the current limitations on the water-to-binder ratio and unit water content need to be modified using lower values. In particular, a rational mixture proportion approach of lightweight concrete needs to be established for the targeted requirements of initial slump, 28-day compressive strength, air content and dry unit weight. Ultimately, significant revision of the concrete standard specifications is required considering the characteristics of domestic artificial lightweight aggregates.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.4
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• pp.65-72
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• 2013

The physical, mechanical, water purification and temperature properties of fiber reinforced porous hwang-toh green roof concrete have been evaluated in this study. The effect of the depending on replacement ratio of blast furnace slag to cement was investigated such that the replacement ratio is varied to 0 % and 30 %. Also, the replacement ratios of hwang-toh were 0, 20 and 30 %. The polyvinyl alcohol fiber was used for the reinforcing fiber. A series of pH test, unit weight, void ratio, compressive strength, after purification and variation of temperature test have been performed to evaluate the performance, water purification effect and temperature properties of the fiber reinforced porous hwang-toh green roof concrete. The test results indicate that the physical and mechanical properties of fiber reinforced porous hwang-toh green roof concrete is affected by the replacement ratio of the blast furnace slag and hwang-toh contents. Results of purifying water showed that the water purification effect of porous hwang-toh green roof concrete is about 40 %. Also, the temperature properties test results indicate the green roof blocks using fiber reinforced porous hwang-toh green roof concrete have insulation and temperature reduction effect.

• Journal of Ocean Engineering and Technology
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• v.17 no.4
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• pp.16-22
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• 2003

The mechanical characteristics of newly recycled aggregate concrete on the basis of the proposed mix design model have been studied to develop the precast artificial fishing reefs. In the first task, the experimental test for the recycled aggregates taken from Jeju Island has been carried out to verify the material properties in terms of specific gravity, percentage of solids, absorption and abrasion of coarse aggregates. In the second task, the experimental parameters of newly recycled aggregate concrete are investigated to meet with the requirements of guidelines with respect to slump, unit weight, pH, ultrasonic velocity, void ratio, and compressive strength which are made of sea-shore sand ad slag cement. The natural aggregate and polypropylene fiber are added to newly recycled aggregate concrete to improve the compressive strength and quality. The optimal mix proportions for compressive strength are W/C=30％, S/a=15％, NA/G=50％ in porous concrete case, W/C=40％, S/a=45％ in plain concrete case, and W/C=40％, S/a-45％, PF=1.0kg/㎥ in fiber reinforced concrete case.

• Magazine of the Korea Concrete Institute
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• v.6 no.5
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• pp.203-212
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• 1994

The setting and hardening of concrete is accompanied by nonlinear temperature distribution caused by developing heat of cement hydration. This leads to tensile stresses that may exceed the strength of the young concrete, and cracks occur. In this present study, the heat of hydration characteristics are obtained from a study in which insulated concrete cubes were tested. Based on test results, concrete heat of hydration characteristics according to unit weight cement and flyash replacement quantity are determined, then employed in a numerical temperature analysis that consider both environmental interaction and concreting phases. The numerical results are performed by ADINA - T. The analytical results are in good agreement with experimental data.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.1
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• pp.53-62
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• 2024

In this paper, an experimental study on the strengths and material properties of concrete manufactured by using coal gangue, as a fine aggregate was conducted. Experimental parameters included coal gangue aggregate contents as a replacement of fine aggregate by 50 % and 100 % (by volume) and fly ash contents. The water-binder ratio was fixed at 0.38. In addition, 30 % of the OPC binder was replaced with fly ash in some mixtures. Test of the unit weight, compressive, split tensile, and flexural tensile strength of concrete were performed and test results were analyzed. Unit weight, compressive strength, split tensile strength, and flexural tensile strength decreased as the coal recycled aggregates increased. In addition, TGA and SEM experiments, which are microstructure experiments, were conducted to analyze thermogravimetric analysis and ITZ by section.

• Journal of the Korea Concrete Institute
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• v.11 no.3
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• pp.123-130
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• 1999

In a preceding study(1), the using method of garnet powder has been studies through the various investigation of basic material properties on garnet powder, industrial by-products generated in Yungju, Kyungpook. In this study, the various properties of concrete mixed with garnet powder are examined as following condition : Unit weight of water (170kg/㎥), water-binder ratio W/B (53, 55 and 58%), sand-aggregate ratio (S/A) (43, 45 and 48%), substitutional ratio of garnet powder of 0, 5, 10, 15 and 20%. Slump increased a little as the substitutional ratio of garnet increased. Air content decreased a little at the substitutional ratio of 10%. or more. Though there is a little difference in compressive strength according to the W/B and the substitutional ratio, compressive strength of concrete using garnet exceeded that of plain concrete a little in the range of the substitutional ration of 5 to 15%. Also, There is a similar tendency in the tensile and flexural strength. Therefore, the use of garnet powder with industrial by-products is expected to improve the workability and the strength of concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.701-704
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• 2008

Actuality, amount of electric power is rising together with business expansion. But the most power plant is consisted a thermal power. People have been burning fuel like a coal, and it bring the cinder concrete. Fly-ash is use to the high-degree in construction material, but in case of bottom-ash had been disused the whole quantity. Intermittently, the academic world laid his studies for bottom-ash. Thus, this study contents are a characteristic of be not harden concrete incorporating fine aggregate, a strength of harden concrete, elastic modulus and a unit mass. And there do for the sake to examine utility value of bottom-ash and improve of light weight concrete.

• Journal of the Korea Institute of Building Construction
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• v.18 no.2
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• pp.133-140
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• 2018

The objective of this study is to propose a reliable mixing design procedure of concrete using artificial lightweight aggregate produced from expanded bottom ash and dredged soil. Based on test results obtained from 25 mixes, empirical equations to determine water-to-cement ratio, unit cement content, and replacement level of lightweight fine aggregates were formulated with regard to the targeted performance (compressive strength, dry density, initial slump, and air content) of lightweight aggregate concrete. From the proposed equations and absolute volume mixing concept, unit weight of each ingredient was calculated. The proposed mix design procedure limits the fine aggregate-to-total aggregate ratio by considering the replacement level of lightweight fine aggregates, different to previous approach for expanded fly ash and clay-based lightweight aggregate concrete. Thus, it is expected that the proposed procedure is effectively applied for determining the first trial mixing proportions for the designed requirements of concrete.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.425-432
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• 2023

In this study, we aim to develop a carbon-reducing concrete technology by incorporating biochar. Performance evaluation experiments were conducted on concrete mixtures containing biochar with insulating and carbon-capturing properties, which are essential for key infrastructure sectors such as construction and tunnels. Concrete mixtures were designed with different biochar incorporation rates of 0 %, 5 %, 10 %, 15 %, and 20 %, as w ell as w ater-to-binder ratios of 0.25, 0.30, 0.35, and 0.40. To assess the physical properties of each mixture, unit weight, total porosity, and permeability were measured, while mechanical properties were determined through the measurement of concrete compressive and flexural strengths. Key factors for enhancing the insulating effect of carbon-reducing concrete containing biochar were identified through regression analysis, indicating a close correlation among biochar incorporation rate, unit weight, concrete strength, and thermal conductivity. It is anticipated that it can be utilized as an insulating material to enhance thermal performance in northern regions with severe winter climates.