• Proceedings of the Korea Contents Association Conference
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• 2014.11a
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• pp.139-140
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• 2014

최근 건선산업에서 문제점으로 지적되고 있는 것은 제조과정 중 이산화탄소를 다량 방생시키는 시멘트의 사용이다. 이는 알칼리활성 무기결합재로 대체함으로써 시멘트보다 이산화탄소 배출량을 저감할 수 있지만 고가의 알칼리 자극제를 다량 사용하기 때문에 경제적 측면 및 사용성을 고려하지 않으면 사용할 수 없기 때문에 이에 대한 대체재에 관한 연구가 필요한 실정이다. 이에 본 연구에서는 고로슬래그를 기반으로 하는 알칼리 활성 무기결합재에 알칼리 자극제의 사용량을 저감하기 위해 레드머드를 사용하고, 레드머드에 적합한 알칼리 자극제의 종류와 사용방법에 대하여 연구하고자 하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.1
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• pp.85-92
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• 2021

The purpose of this study is to investigate the properties of hardener-free epoxy-modified mortars(EMMs) using ground granulated blast furnace slag(GGBFS) and alkali activators. The hardener-free EMMs with a GGBFS content of 20% using 4 types of alkali activators were prepared with various polymer-binder ratios, and tested for strengths, water absorption, carbonation depth, chloride ion and H2SO4 penetration depth. The conclusions obtained from the test results are summarized as follows: The compressive strength of the EMMs with a GGBFS content of 20% attains a maximum at a polymer-binder ratio of 10%. The flexural strength of the hardener-free EMMs using Ca(OH)2 as a alkali activator is improved with increasing polymer-binder ratios. However, the flexural strength of the EMMs using NaCO3, Na2SO4 and Li2CO3 is gradually decreased with increasing polymer-binder ratios. Regardless of the type of alkali activator, the water absorption, chloride ion penetration and carbonation depth are remarkably decreased with increasing polymer-binder ratios due to the epoxy film formed in the EMMs. The H2SO4 penetration depth of the hardener-free EMMs with a GGBFS content of 20% is gradually increased with increasing polymer-binder ratio. In this study, the properties of hardener-free EMMs using Ca(OH)2 as a alkali activator are more excellent than those of other alkali activators.

• Journal of the Korean GEO-environmental Society
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• v.23 no.4
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• pp.21-27
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• 2022

Recently, numerous studies are being performed to examine alkali-activated cement which uses industrial by-products, such as GGBS and fly ash, as well as alkali activators. Alkali-activated cement is a type of binder that exerts the same strength as cement without using cement by mixing industrial by-products with alkali activators. Alkali activators, which are used mainly for carbon-reducing technologies and alkali activation, are expensive and difficult to apply in the field due to risks related to strong alkalinity. Therefore, this study intends to explore methods to use red mud as a substitute for an alkali activator. To that end, this study has evaluated engineering properties, such as flow and strength, of CLSM that uses red mud and paper sludge ash as binders and its possibility to cause soil pollution. This study also aims to present the appropriate mixing ratios of red mud and paper sludge ash to produce CLSM.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.3
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• pp.120-128
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• 2005

In the construction industry, due to the cost rise of raw material for concrete, we have looked into recycling by-products which came from foundry. When using the Ground Granulated Blast-Furnace Slag(SG), it is good for enhancing the qualities of concrete such as reducing hydration heat, increasing fluidity, long-term strength and durability, but it has some problems : construction time is increased or the rotation rate of form is decreased due to low development of early strength. In this study, therefore, to enhance the early strength of SG mortar, we used some alkali activators(KOH, NaOH, $Na_2CO_3$, $Na_2SO_4$, water glass, $Ca(OH)_2$, alum. This paper deals with reacted products, setting time, heat evolution rate, flow and the strength development of SG cement mortar activated by alkali activators. From the results, if alkali activators were selected and added properly, SG is good for using as the materials of mortar and concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.525-528
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• 2008

This study is performed to know influence on the hydration according to alkali activator and method of pulverization and fineness in slag-cement. The compressive strength of mortar were examined when the SG powder of which the specific surface area are 4,000, 6,000, and 8000cm$^2$/g were substituted for 50wt.% of ordinary portland cement. Na$_2$SO$_4$, Ca(OH)$_2$, NaOH were used as alkali activator. respectively, As the results, the compressive strength of mortar increased as following the order, Na$_2$SO$_4$>Ca(OH)$_2$>None>NaOH until 7days. But at 28days, mortar used Ca(OH)$_2$ as alkali activator were the highest strength.

• Journal of the Korea Institute of Building Construction
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• v.13 no.4
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• pp.351-359
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• 2013

Blast furnace slag (BFS) have many advantages that are related to effective value improvement on applying to concrete while side effects of blast furnace slag also appear. Thus, research team conducted an experiment with high volume slag to see if the attribute of waste alkali accelerator for mixing rate, mixed use of NaOH and $Na_2SiO_3$, and early strength agent for mixing rate for replacement ratio and for the types of the stimulants in order to increase the use of blast furnace slag1s powder. As the result of the experiment, when it comes to compression strength, all of the alkali stimulants have been improved as the replacement rate increases except for sodium hydroxide. Among the alkali stimulants, sodium silicate was high on dynamic elastic modulus and absorption factor. In case of early strength agent, the mix of mixing 1.5% and blast furnace slag 75% have showed high strength enhancement. In event of Waste Alkali accelerator, it has showed different consequences for each experiment.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2004.05a
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• pp.143-148
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• 2004

고로슬래그 미분말과 플라이 애쉬와 같은 재료들이 콘크리트의 내구성과 장기강도 증진을 목적으로 혼합재로서 사용되고 있다. 본 연구에서는 고로슬래그 사용 몰탈의 내구성 증진 특성을 활용하기 위하여 고로슬래그 미분말에 알칼리 자극제를 첨가한 알칼리 활성화 슬래그계 무기결합재 사용 몰탈의 내구성과 물리적 특성을 평가하였다. 실험결과, 몰탈의 초기 압축강도 발현에 알칼리 자극제가 큰 영향을 미치는 것을 확인하였다. 또한 알칼리 자극제가 첨가된 몰탈의 화학적 저항성을 평가하기 위하여 공시체를 재령 28 일 후, 5% 황산($H_2SO_4$) 용액에 침지하여 압축강도 및 질량 변화를 관찰하였다. 그 결과, 보통포틀랜드 시멘트로 제조한 몰탈의 경우, 황산용액 침지 후 압축강도가 54% 감소하였다. 반면 고로슬래그 미분말을 첨가한 몰탈의 경우, 약 10% 강도가 감소하였다. 질량변화의 경우, 보통포틀랜드 시멘트로 제조한 공시체는 17%, 고로슬래그 미분말을 첨가한 몰탈은 3%의 질량변화를 보였다. 이 결과로서 고로슬래그 미분말을 첨가한 몰탈의 경우, 화학적 저항성과 물리적 특성이 우수한 것을 확인하였다.

• Journal of the Korea Institute of Building Construction
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• v.10 no.6
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• pp.61-66
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• 2010

As global warming has had harmful effects on the environment, the construction industry has made efforts to reduce the amount of $CO_2$ generated in the process of cement production. There is an urgent need for an alternative material that can replace cement. To improve the initial strength and economical efficiency pointed out as problems, this research was conducted for Blast Furnace Slag (BFS), an industrial byproduct. Non-sintering cement (NSC) was used by minimizing the amount of high-priced alkali activators. By using Nano-technology, fineness has been maximized, to enhance the initial strength of BFS. This research is based on non-sintered cement replaced by nano-slag using alkali activators, and the fundamental properties and quality of the non-sintered cement were investigated. A variety of activators were used, up to 10 percent of the slag weight. This research aims to present fundamental data through a comparative analysis of flexural strength, compressive strength, time of setting, diabetic temperature, and rising heat.

• Journal of the Korea Institute of Building Construction
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• v.14 no.4
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• pp.301-307
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• 2014

In order to reduce the emission of carbon dioxide($CO_2$), this research use blast furnace slag in concrete manufacture, as 100% replacement of cement. The aim of this study is to investigate the density and strength properties of alkali-activated lightweight composites with alkali activators of different types and different amounts. The bubble for achieving the lightweight of alkali-activated lightweight composites was generated in the reaction between the paper ash and the alkali activators instead of using a foaming agent. Lightweight formed concrete was conducted basic experimental for determining replacement ratio of paper ash. Then, the density and strength were measured according to the types and the contents of the alkali accelerator that can react with the paper ash. As results, the optimum replacement ratio of the paper ash was 5%. The alkali activator containing NaOH 12.5% obtained the lowest weight of $1.13g/cm^3$. Also, compressive strength were relatively high. Therefore, this study demonstrated that alkali accelerator with a certain amount of NaOH can achieve relatively high strength and lightweight alkali-activated lightweight composites.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.4
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• pp.360-366
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• 2014

In this study, effect of types and replacement ratio of alkali activator on compressive strength of ground granulated blast furnace slag mortar has been reviewed. Types of alkali activator are NaOH, $Ca(OH)_2$, $Na_2SO_4$, and KOH. Replacement ratio of alkali activator is 7.5, 10, 12.5, and 15%, respectively. As results, under high temperature curing condition, 1 day compressive strength development with NaOH and KOH was higher than that of $Ca(OH)_2$ and $Na_2SO_4$. Regardless of types of alkali activator, compressive strength increased with increasing pH. This can be explained by the fact that impermeable film on the surface of slag which is generated when slag contacts water has been destroyed by alkali activator, and this promotes hydration reaction. Also, 1 day age compressive strength of specimen with high temperature curing was higher than that of specimen with standard curing. 28 days age compressive strength of specimen with high temperature curing was less than or equal to that of specimen with standard curing.