• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.269-275
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• 2022

In this study, the setting time and compressive strength of cement paste composites applied with nano-micro pozzolanic binders were experimental analyzed. The pozzolanic binder was reduced initial and final setting time and the compressive strength was increased. Micro silica was effective in decrease the initial setting and final setting time and impressing the compressive strength. When two or more cement binders were used, the using of silica fume and a small amount of nano silica at reduced the setting time to 62-64 % to OPC cement and the compressive strength was increased to 117 %. A small amount of mixing the nano silica was effect to pore filling and pozzolanic activation. However, the addition of a chemical admixture should be considered when mixing table design because pozzolanic binders high specific surface area causes a decrease in cement composites flow.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.797-800
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• 2008

To decrease the usage of cement, the pozzolan reaction materials are used as a mineral admixture. Hwang Toh which is broadly deposited in Korea is well known as a environment friendly material and the activated Hwang Toh which has the property of pozzolan reaction is practically used as a mineral admixture of concrete. PET fiber which is made by recycled PET bottle controls micro crack in concrete. But the study about concrete mixed with reinforcing fiber is not enough and the property of Hwang Toh concrete mixed with PET fiber is more complicated case. So this study performed drying shrinkage experiment to analyse mechanical property of Hwang Toh concrete mixed with PET fiber.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.335-336
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• 2010

This paper presents experimentally investigated the effects of pozzolan made from various by-Product materials on mechanical properties of mortar. Fly ash(FA), slag (BFS), and palm oil fuel ash (POFA) were partially used to replace Portland cement. The results suggest that mortars containing FA, BFS, and POFA can be used as pozzolanic materials in making concrete with 28day compressive strength. After curing, the mortar containing 10-30% FA or POFA, and 30% BFS exhibited compressive strengths that of the original Portland cement (OPC). The use of FA, POFA, and BFS to partially replace Portland cement has evaluation method of the Assessed Pozzolan-activity index.(API)

• Journal of the Korea Concrete Institute
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• v.13 no.2
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• pp.123-129
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• 2001

Pozzolan is to improve the strength and the durability of concrete as a result of the pozzolanic reaction, Broadly speaking, pozzolanic materials can be artificial materials, such as slica fume and fly ash, and natural material, such as rice husk ash, clay, volcanic ash, clayish pozzolan. Hwangtoh is a mineral which belongs to a group of matakaolin, especially halloysite, and the main elements is SiO$_2$, Al$_2$O$_3$, Fe$_2$O$_3$. The purpose of this study is to examine the application of Hwangtoh for the concrete admixtures, the composition of this study is shown as follows. Chapter I is analysis for properties of concrete as the kinds of admixture, and Chapter H is analysis for properties of concrete as the replacement ratio of activated Hwangtoh. As a result of this study, Hwangtoh is found to have high practical use as pozzolanic material, and the pertinent range of replacement ratios of Hwangtoh on cement are 10∼20 %.

• Journal of the Korea Concrete Institute
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• v.21 no.3
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• pp.265-273
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• 2009

There have been numerous studies to develop eco-friendly concrete. The attempt to reduce the amount of cement used is suggested as one of the solutions for eco-friendly concrete. To decrease the usage of cement, the pozzolan reaction materials are used as a mineral admixture. Hwang-toh, which is broadly deposited in Korea is a well known environment friendly material and the activated hwang-toh, which has the property of pozzolan reaction, is alternatively used as a mineral admixture of concrete. The purpose of this study is to investigate the drying shrinkage of hwang-toh concrete mixed with recycled PET fiber. Therefore, drying shrinkage experiments are performed to analyze mechanical property of hwang-toh concrete mixed with recycled PET fiber. Test results showed that the drying shrinkage is controlled by hwang-toh admixture and PET fiber.

• Journal of the Korean GEO-environmental Society
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• v.4 no.4
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• pp.35-43
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• 2003

In this study, the physical and chemical characteristics of incinerated pulp and sewage sludge ashes for recycling and reuse were examined. Then we studied the application to the cement admixture by pozzolanic reaction. The particle size of incinerated pulp and sewage sludge ashes was distributed around $10{\sim}100{\mu}$, and the contents of $SiO_2$ and $Al_2O_3$ were 45.8~51.0%, respectively. Compressive strengths of the solidified ashes were relatively higher, when the content of substituted incineration ashes was 10% and the porosity was also lower except for the case of sewage sludge ash. As results, it is shown that it may be possible to recycle incinerated pulp sludge ashes as cement admixtures.

• Proceedings of the Korea Concrete Institute Conference
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• 1991.04a
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• pp.1-14
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• 1991

환경문제로 인한 Nox의 규제로 보일러의 연소 온도가 저하되어 미연소탄과 조립분이 증가되었다. 이러한 플라이 애쉬의 미연소탄과 양호하지 못한 입자형상들은 콘크리트용 혼화재로서 플라이 애쉬의 품질을 현저하게 저하시키고 있다. 이 저 품질의 플라이 애쉬를 44$\mu$체를 사용하여 체 분급의 방법을 도입하므로서 어느 정도 양질의 플라이 애쉬로 개선될수 있었다. 분급한 9종의 플라이 애쉬를 시험한 결과 입자형상이 구형으로 개선되었으며, 물리.화학적 특성이 다소 개선되었고 압축강도가 증가되었다. 그리고 분말도와 포졸란 활성지수, 44$\mu$체 잔량과 포졸란 활성지수는 좋은 상관관계를 보여주었다. 또한 분급에 의한 분말도 관리가 포졸란 활성에 영향을 주는 인자임을 알 수 있었다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2002.05a
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• pp.85-90
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• 2002

This study aims to propose a fundamental report for pozzolan reaction of discarded Bentonite by heat-treatment as concrete mineral admixture. As discarded bentonite is clay mineral to contain a great quantity a lot of $SiO_2$ and $Al_{2}O_{3}$, it is anticipated to reveal pozzolan reaction ability by heat-treatment. To find out pozzolan reaction ability of discarded Bentonite slurry by heat-treatment, the experiment is excuted Phenolphtalein test, setting test, pH test and the analysis by X-ray diffractor. As a result of this study, discarded Bentonite slurry can be utilized as concrete mineral admixture by heat-treatment and especially, pozzolan reaction ability of discarded Bentonite slurry is superior to the situation of 50$0^{\circ}C$~$700^{\circ}C$, 60min.

• Journal of the Korea Concrete Institute
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• v.27 no.1
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• pp.65-73
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• 2015

This study discussed the pozzolanic properties of calcined sewage sludge (CSS) according to calcination and fineness conditions. The chemical and mineralogical analysis of CSS according to calcination temperature and time were carried out and compared with that of the existing pozzolanic materials such as fly-ash, blast furnance slag and meta-kaolin. Various mortars were made by mixing those CSS and $Ca(OH)_2$ (1:1 wt. %), and their compressive strength and hydrates according to experimental factors such as fineness of CSS and curing age were also investigated in detail. The results show clearly the potentiality of calcined sewage sludge (CSS) as an admixture materials in concrete, but the CSS should be controlled by calcination temperature and time, and fineness etc. In this experimental condition, the calcination temperature of $800^{\circ}C$, calcination time of 2 hours and fineness of $5,000cm^2/g$ were optimum conditions in consideration of the mechanical properties and economic efficiency of CSS. The compressive strength of CSS mortars was higher than that of fly-ash mortars and blast furnace slag mortars, especially at the early ages. Then, the utilization of CSS in construction fields was greatly expected.

• Journal of the Korea Institute of Building Construction
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• v.6 no.1 s.19
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• pp.109-115
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• 2006

Although the clays were one of the major materials of building constructions, presently, its functions are lesser and the cements take its place as building materials. however, the IAQ problems such as $CO_2$ increase, Rn gas and VOCs occurrence should be imperative from production and construction processes of the cements. This study aims to develop the alternate clay compounds to cements and analyze its properties by experimental tests. For the study, the claymineral of Chungchong-bukdo 10 areas are used. The chemical and structural properties are experimentally analyzed and the pozzolan reaction possibilities of clays are executed.