나트륨계 알칼리 활성화제를 사용한 친환경 알카리활성 슬래그 섬유보강콘크리트 보의 휨성능 평가

하기주,이동렬,하재훈 한국구조물진단유지관리공학회 2015 한국구조물진단유지관리공학회 논문집 Vol.19 No.2

In this study, it was developed eco-friendly alkali-activated slag fiber reinforced concrete using ground granulated blast furnace slag, alkali activator (water glass, sodium hydroxides), and steel fiber. Eight reinforced concrete beam using alkali-activated slag concrete were constructed and tested under monotonic loading. The major variables were mixture ratio of alkali activator, mixed/without of steel fiber. Experimental programs were carried out to improve and evaluate the flexural performance of such test specimens, such as the load-displacement, the failure mode, the maximum load carrying capacity, and ductility capacity. All the specimens were modeled in scale-down size. The reinforced concrete beams using the eco-friendly alkali-activated slag fiber reinforced concrete was failed by the flexure or flexure-shear in general. In addition, the maximum strength increased with the adding the mol of sodium hydroxide, and the specimen reinforced the steel fiber showed the value of maximum strength which is increased by 15.8% through 25.9%. It is thought that eco-friendly alkali-activated slag fiber reinforced concrete can be used with construction material and product to replace normal concrete. If there is applied to structures such as precast concrete member and production of 2nd concrete product, it could be improved the productivity and reduction of construction duration etc. 이 연구에서는 산업부산물인 알카리활성 슬래그와 알칼리 활성화제 (물유리, 수산화나트륨)에 강섬유를 사용하였으며, 이를 철근콘크리트 보에 적용하여 휨성능 평가를 하였다. 주요변수는 알칼리 활성화제의 혼입비율 및 강섬유를 혼입으로 총 8개의 실험체를 제작하였으며, 재료 및 구조성능 평가를 위한 실험을 수행한 결과 다음과 같은 결론을 얻었다. 친환경 알카리활성 슬래그 섬유보강콘크리트를 사용한 철근콘크리트 보는 전반적으로 휨 또는 휨-전단에 의하여 파괴되었다. 그리고 수산화나트륨의 몰 증가와 강섬유를 보강한 결과 최대내력이15.8~25.9% 증가한 값이 나타났으며, 연성 또한 높게 나타났다. 친환경 알카리활성 슬래그 섬유보강콘크리트는 기존의 콘크리트를 대체할수 있는 기초연구로서 향후 건설소재 및 재료분야에 활용할 수 있을 것으로 사료되며, 이러한 특성을 바탕으로 콘크리트 2차 제품 생산과구조부재를 PC화하여 활용할 경우 생산성 향상, 공기단축 등 효율이 상승될 것으로 보인다.

알칼리금속과 알칼리 토금속 촉매 담지 대나무 활성탄의 NO 가스 반응 특성

박영철 ( Young Cheol Bak ),최주홍 ( Joo Hong Choi ) 한국화학공학회 2016 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.54 No.5

대나무를 원료로 탄화 및 활성화온도 900 oC에서 대나무 활성탄을 만들고, 이 대나무 활성탄에 알칼리 금속(Na, K)과 알칼리토금속(Ca, Mg)을 담지 시켜 알칼리 담지 대나무활성탄을 제조하였다. 제조된 알칼리 담지 활성탄의 비표면적 및 세공분포 등의 물리적 특성을 분석하였다. 또한 폐 대나무활성탄의 재활용을 위하여 알칼리 담지 대나무활성탄과 NO 기체의 반응 특성 실험을 열중량분석기를 사용하여 비등온반응(반응온도 20~850 oC, NO 농도 0.1 kPa)과 등온반응(반응온도 600, 650, 700, 750, 800, 850 oC, NO 농도 0.1~1.8 kPa) 조건에서 하였다. 실험 결과, 대나무 활성탄 특성 분석에서 알칼리 담지 대나무 활성탄에서는 알칼리 담지량이 증가할수록 세공 부피와 표면적이 감소하였다. 비등온과 등온 NO 반응에서는 전체적으로 Ca금속담지 대나무활성탄[BA(Ca)]과 Na금속담지 대나무활성탄[BA(Na)], K금속담지 대나무활성탄[BA(K)], Mg금속담지 대나무활성탄[BA(Mg)]이 대나무활성탄[BA]에 비하여 반응속도가 향상되는 것을 볼 수 있다. BA(Ca)> BA(Na)> BA(K)> BA(Mg)> BA 순으로 촉매 활성이 유효하였다. NO 반응에서의 활성화에너지는 82.87 kJ/mol[BA], 37.85 kJ/mol[BA(Na)], 69.98 kJ/mol[BA(K)], 33.43 kJ/mol[BA(Ca)], 88.90 kJ/mol [BA(Mg)]로 나타났고, NO 분압에 대한 반응차수는 0.76[BA], 0.63[BA(Na)], 0.77[BA(K)], 0.42[BA(Ca)], 0.30[BA(Mg)] 이었다. The impregnated alkali metal (Na, K), and the alkali earth metal (Ca, Mg) activated carbons were produced from the bamboo activated carbon by soaking method of alkali metals and alkali earth metals solution. The carbonization and activation of raw material was conducted at 900 oC. The specific surface area and the pore size distribution of the prepared activated carbons were measured. Also, NO and activated carbon reaction were conducted in a thermogravimetric analyzer in order to use for de-NOx agents of the used activated carbon. Carbon-NO reactions were carried out in the nonisothermal condition (the reaction temperature 20~850 oC, NO 1 kPa) and the isothermal condition (the reaction temperature 600, 650, 700, 750, 800, 850 oC, NO 0.1~1.8 kPa). As results, the specific volume and the surface area of the impregnated alkali bamboo activated carbons were decreased with increasing amounts of the alkali. In the NO reaction, the reaction rate of the impregnated alkali bamboo activated carbons was promoted to compare with that of the bamboo activated carbon [BA] in the order of BA(Ca)> BA(Na)> BA(K)> BA(Mg) > BA. Measured the reaction orders of NO concentration and the activation energy were 0.76[BA], 0.63[BA(Na)], 0.77[BA(K)], 0.4 [BA(Ca)], 0.30 [BA(Mg)], and 82.87 kJ/mol[BA], 37.85 kJ/mol[BA(Na)], 69.98 kJ/mol[BA(K)], 33.43 kJ/mol[B (Ca)], 88.90 kJ/mol [BA(Mg)], respectively.

알칼리 자극제의 종류 및 첨가율에 따른무시멘트 경량 경화체의 강도특성

이상수,김윤미,박선규 한국건축시공학회 2014 한국건축시공학회지 Vol.14 No.4

본 연구는 포틀랜드 시멘트를 사용하지 않고 산업부산물인 고로슬래그를 기반으로 제지애시와 알칼리 자극제를 사용하여 기포를 발생시킴으로써 경량 패널의 심재 및 충전재등에 사용할 수 있는 무시멘트 경량 경화체를 개발하고자하였다. 이를 위하여 먼저 제지애시의 적정 치환율을 도출하기 위한 기초실험을 실시하였다. 기초 실험을 바탕으로 제지애시와 반응하여 수소기체를 발생시킬 수 있는 알칼리 자극제의 종류 및 첨가율에 따라 본 실험을 실시하였으며, 제조된 시험체를 대상으로 재령별 겉보기 밀도와 강도를 측정하였다. 그 결과 제지애시의 적정 치환율은 5%이며, 알칼리 자극제는 NaOH를 12.5% 첨가한 경화체의 겉보기 밀도가1.13g/㎤, 감소율 40.45%로 가장 낮은 겉보기 밀도를 나타내었으며, 겉보기 밀도와 비교하여 비교적 높은 강도를 발현하였다. 따라서, 알칼리 자극제로써 NaOH를 적정량 사용하고제지애시와의 반응시간을 늦출 수 있는 방법을 강구한다면보다 높은 강도와 경량성을 겸비한 무시멘트 경량 경화체를제조할 수 있을 것으로 판단된다. In order to reduce the emission of carbon dioxide(CO2), 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 ofalkali-activated lightweight composites with alkali activators of different types and different amounts. The bubble forachieving the lightweight of alkali-activated lightweight composites was generated in the reaction between the paperash and the alkali activators instead of using a foaming agent. Lightweight formed concrete was conducted basicexperimental for determining replacement ratio of paper ash. Then, the density and strength were measured accordingto the types and the contents of the alkali accelerator that can react with the paper ash. As results, the optimumreplacement ratio of the paper ash was 5%. The alkali activator containing NaOH 12.5% obtained the lowest weightof 1.13g/㎤. Also, compressive strength were relatively high. Therefore, this study demonstrated that alkali acceleratorwith a certain amount of NaOH can achieve relatively high strength and lightweight alkali-activated lightweightcomposites.

알칼리활성화제 치환율에 따른 무시멘트 다공성 콘크리트의 물리·역학적 특성

김동현,김춘수,박찬기,Kim, Dong-Hyun,Kim, Chun-Soo,Park, Chan Gi 한국농공학회 2013 한국농공학회논문집 Vol.55 No.2

The present study is to evaluate physical and mechanical properties of porous concrete having non cement that mainly causes carbon emission. This study aims to explore eco-friendly concrete technology capable of reducing the amount of carbon emission due to the use of normal cement by substituting it with non cement porous concrete to which alkali-activator and blast-furnace slag powder are impregnated. As experimental variables, 5 %, 6 %, 7 %, 8 %, 9 % and 10 % of alkali-activator were substituted as binders and applied. Testing evaluated in this study were pH value, void ratio, compressive strength and residual compressive strength shown after being immersed in $H_2SO_4$ solution and $Na_2SO_4$ solution. The test results were compared with those tested with the use of porous concrete to which 400 $kg/m^3$ of unit cement amount was applied as binder. In consequence, it was concluded that; as for pH value, it was decreased than was the case in which cement was used, but increased with the more the use of alkali activator; as for void ratio and compressive strength, the mix proportion in which 9 % and 10 % of alkali activator were applied in terms of substitution ratio showed the result similar to the mixture in which 400 $kg/m^3$ of unit cement ratio was applied; and, as for residual compressive strength in the case of being immersed in $H_2SO_4$ solution and $Na_2SO_4$ solution, the compressive strength was increased, thus leading to improved chemical resistance.

Mechanical Performance of Alkali-activated Stabilized Sandy Soil Reinforced with Glass Wool Residue Microfibers

Mohamad Kianynejad,Mohamad Mohsen Toufigh,Vahid Toufigh 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.2

Alkali-activated binders have been introduced as promising alternatives to conventional binders such as lime and ordinary Portland cement (OPC). However, alkali-activated materials exhibit a brittle behavior and crack formation due to tensile stresses is inevitable. To overcome these limitations, incorporation of fibers into the cementitious matrix is among the well-known techniques to improve the flexural behavior and energy absorption of the corresponding composites. The present study aimed to investigate the feasibility of using reinforced alkali-activated metakaolin as an alternative to common stabilizers to improve the engineering characteristics of sandy soil. Calcium carbide residue (CCR) was used as an alkali activator, and glass wool residue (GWR) microfibers were used as reinforcement elements to maximize waste stream utilization. Unconfined compressive strength (UCS), California bearing ratio (CBR), and three-point bending tests were performed to evaluate the mechanical behavior of the alkali-activated products. Moreover, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were employed to determine the microstructure and elemental composition of these products. The results indicate that the compressive strength and ductile behavior of the stabilized soil samples improved significantly. Furthermore, the SEM/EDX analysis of the reinforced alkali-activated samples revealed the interfacial bond between the microfibers and alkali-activated binding gel, enhancing the mechanical performance between the microfibers and cementitious matrix.

알칼리 활성화제를 첨가한 페로니켈슬래그 혼입 삼성분계 콘크리트의 동결융해 저항성

조원정,박광필,안기용 한국건설순환자원학회 2022 한국건설순환자원학회 논문집 Vol.10 No.2

The present study assessed the micro structure and durability characteristics of ternary blended cement with different types of alkali activators. Ground granulated blast furnace slag(GGBS) and ferronickel slag(FNS) was replaced until 50 % of the weight o f cement. In a dditio n, p otassuim hydro xide a nd s o dium h ydro xide w ere used f o r comparing the pro perties o f different type of alkali activator. Ternary blended cement with alkali activators showed higher peak portlandite peak than that of OPC(Ordinary Portlande Cement) and non activated ternary blended cement. Also, there was no new hydration products in ternary blended cement or/and alkali activators. Based on the mercury intrustion porosimetry(MIP) test result, ternary blended cement increased macro pore while alkali activated ternary blended cement modified pore structure and increased microp pore as compared to OPC as control. Combination with alkali activators is desirable to enhance the compressive strength and freeze thaw resistance.

나트륨계 알칼리 활성화제를 사용한 친환경 알카리활성 슬래그 섬유보강콘크리트 보의 휨성능 평가

하기주,이동렬,하재훈 한국구조물진단유지관리공학회 2015 한국구조물진단유지관리공학회 논문집 Vol.19 No.2

In this study, it was developed eco-friendly alkali-activated slag fiber reinforced concrete using ground granulated blast furnace slag, alkali activator (water glass, sodium hydroxides), and steel fiber. Eight reinforced concrete beam using alkali-activated slag concrete were constructed and tested under monotonic loading. The major variables were mixture ratio of alkali activator, mixed/without of steel fiber. Experimental programs were carried out to improve and evaluate the flexural performance of such test specimens, such as the load-displacement, the failure mode, the maximum load carrying capacity, and ductility capacity. All the specimens were modeled in scale-down size. The reinforced concrete beams using the eco-friendly alkali-activated slag fiber reinforced concrete was failed by the flexure or flexure-shear in general. In addition, the maximum strength increased with the adding the mol of sodium hydroxide, and the specimen reinforced the steel fiber showed the value of maximum strength which is increased by 15.8% through 25.9%. It is thought that eco-friendly alkali-activated slag fiber reinforced concrete can be used with construction material and product to replace normal concrete. If there is applied to structures such as precast concrete member and production of 2nd concrete product, it could be improved the productivity and reduction of construction duration etc.

알칼리 활성 슬래그 콘크리트의 내구성: 콘크리트의 염소이온 확산

홍기남 ( Ki Nam Hong ),박재규 ( Jae Kyu Park ),정규산 ( Kyu San Jung ),한상훈 ( Sang Hun Han ),김재현 ( Jae Hyun Kim ) 한국안전학회(구 한국산업안전학회) 2015 한국안전학회지 Vol.30 No.4

The aim of the present study is to investigate some characteristics of concrete according to addition of blast furnace slag and alkali-activator dosages. Blast furnace slag was used at 30%, 50% replacement by weight of cement, and liquid sulfur having NaOH additives was chosen as the alkaline activator. In order to evaluate characteristics of blast furnace slag concrete with sulfur alkali activators, compressive strength test, total porosity, chloride ions diffusion coefficient test were performed. The early-compressive strength characteristics of blast furnace slag concrete using a sulufr-alkali activators was compared with those of reference concrete and added 30, 50% blast furnace slag concrete. Also, Blast furnace slag concrete using sulfur-alkali activators enhanced the total porosity, chloride ions diffusion coefficient than two standard concrete. Alkali-activated blast furnace slag concrete was related to total porosity, compressive strength and chloride ions diffusion coefficient each others. As a result, it should be noted that the sulfur-alkali activators can not only solve the demerit of blast furnace slag concrete but also offer the chloride resistance of blast furnace slag concrete using sulfur alkali activators to normal concrete.

알칼리 활성화된 고로슬래그 페이스트의물리화학적 특성 및 이산화탄소 흡수능 평가

안해영,박철우,박희문,송지현 한국도로학회 2015 한국도로학회논문집 Vol.17 No.2

PURPOSES: In this study, alkali-activated blast-furnace slag (AABFS) was investigated to determine its capacity to absorb carbon dioxide and to demonstrate the feasibility of its use as an alternative to ordinary Portland cement (OPC). In addition, this study was performed to evaluate the influence of the alkali-activator concentration on the absorption capacity and physicochemical characteristics. METHODS: To determine the characteristics of the AABFS as a function of the activator concentration, blast-furnace slag was activated by using calcium hydroxide at mass ratios ranging from 6 to 24%. The AABFS pastes were used to evaluate the carbon dioxide absorption capacity and rate, while the OPC paste was tested under the same conditions for comparison. The changes in the surface morphology and chemical composition before and after the carbon dioxide absorption were analyzed by using SEM and XRF. RESULTS: At an activator concentration of 24%, the AABFS absorbed approximately 42g of carbon dioxide per mass of paste. Meanwhile, the amount of carbon dioxide absorbed onto the OPC was minimal at the same activator concentration, indicating that the AABFS actively absorbed carbon dioxide as a result of the carbonation reaction on its surface. However, the carbon dioxide absorption capacity and rate decreased as the activator concentration increased, because a high concentration of the activator promoted a hydration reaction and formed a dense internal structure, which was confirmed by SEM analysis. The results of the XRF analyses showed that the CaO ratio increased after the carbon dioxide absorption. CONCLUSIONS : The experimental results confirmed that the AABFS was capable of absorbing large amounts of carbon dioxide, suggesting that it can be used as a dry absorbent for carbon capture and sequestration and as a feasible alternative to OPC. In the formation of AABFS, the activator concentration affected the hydration reaction and changed the surface and internal structure, resulting in changes to the carbon dioxide absorption capacity and rate. Accordingly, the activator ratio should be carefully selected to enhance not only the carbon capture capacity but also the physicochemical characteristics of the geopolymer.

수산화나트륨으로 알카리활성화한 Fly ash 시멘트의 강도특성

박상숙 ( Sang-sook Park ),강화영 ( Hwa-young Kang ) 한국환경기술학회 2004 한국환경기술학회지 Vol.5 No.3

본 연구의 목적은 화력발전소에서 배출되는 Fly ash를 수산화나트륨용액으로 활성화 할 경우 Fly ash의 반응성 개선으로 기존 포틀랜트시멘트를 대체할 수 있는지를 평가하였다. 활성화제의 농도(NaOH 2M에서 10M), 물과 fly ash의 비율 그리고 fly ash/모래의 혼합 비율을 달리하여 연구를 수행하였다. 알칼리 활성화된 fly ash로 제조한 시편의 압축강도는 30℃에서 하루동안 양생 후 탈형 한 다음 90℃ 건조기에서 재령 4일에 측정하였다. 8M의 NaOH 농도를 가진 활성화용액 50%와 160%의 fly ash를 혼합하여 제조한 AAF(Alkali Activated Fly ash)의 압축강도는 127kg/㎠로 나타났다. 10M의 NaOH 농도를 가진 활성화용액 40%, fly ash 60% 그리고 150%의 모래를 혼합하여 제조한 AAFS(Alkali Activated Fly ash and Sand)의 압축강도는 113kg/㎠로 나타났다. 이들 조건하에서 제조된 AAF와 AAFS는 시멘트 벽돌의 허용압축강도를 50kg/㎠ 이상으로 규정하는 KS의 조건을 충족시키므로 활성화된 fly ash는 포틀랜트시멘트를 대신할 수 있을 것이다. 더욱이 20%의 염산에 90일간 침지시킨 AAF와 AAFS의 무게손실이 5%인 것을 감안하면 산에 대한 저항성이 극적으로 개선되었음을 알 수 있다. The purpose of this study is to evaluate the potentials for substituted portland cement result from improved the reactivated in case of the activation of fly ash produced from coal-fired power plant with NaOH solution. The parameters of process studied are: different activator concentration(NaOH 2M to 10M), water-to fly ash ratios, and fly ash-to sand ratios. The compressive strength of the specimens manufactured using alkali-activated fly ash was measured of cured at 1day, 25℃ and at 4 days of reaction, 90℃. AAF(Alkali Activated Fly ash) mixture 50% activating solution with 8M NaOH and 160% fly ash develop compressive mechanical strengths of 127 kgf/㎠. AAFS(Alkali Activated Fly ash and Sand) mixture 40% activating solution with 10M NaOH, 60% fly ash and 150% sand develop compressive mechanical strengths of 113 kgf/㎠. The AAF and AAFS manufactured under this conditions have high compressive strength above KS for cement brick(50 kgf/㎠), therefore, activated fly ash can be used substituted for portland cement. Moreover, AAF and AAFS that took place during exposure to 20% concentration of hydrochloric acid-5% weighe loss in 90 days dramatically shows the improved acid resistance.