하수슬러지 전처리 기법별 감량화 및 가용화 특성 평가

김홍석 ( Hong-suck Kim ),김병군 ( Byung-goon Kim ),서인석 ( In-seok Seo ),김연권 ( Youn-kwon Kim ) 한국환경기술학회 2008 한국환경기술학회지 Vol.9 No.3

전처리 기법별 감량화 및 가용화 특성을 평가하기 위해 마이크로파, 오존, 열, 알칼리, 초음파, 알칼리-초음파 및 알칼리-오존 전처리 기법이 연구되었다. 단독처리기법 중에 알칼리와 오존이 가장 높은 감량화율 및 가용화율을 보여주었고 감량화율 면에서 볼 때 알칼리 전처리 기법이 오존 전처리 기법보다 조금 더 높았다. 또한, 복합처리기법 중에서는 알칼리-오존 전처리 기법이 가장 좋은 감량화율 및 가용화율을 보여주었다. NaOH 30 meq/L와 0.32 g O₃/gSS에서의 감량화율과 가용화율이 회분식 실험에서 각각 39.8%와 41.6%를 나타냈으며 계속되는 실험에서 감량화율 및 가용화율은 알칼리-오존 처리법에 의한 회분식 실험에서 보다 10% 낮았다. 또한 알칼리-오존 복합처리(오존과 알칼리가 하나의 반응조에서 전처리됨)기법과 알칼리-오존(알칼리 처리후에 오존이 사용됨)전처리법은 조금 더 높은 가용화율을 보여주었다. 고도처리공정의 외부탄소원으로의 이용과 운영관리 측면에서도 알칼리-오존 복합처리(오존과 알칼리가 하나의 반응조에서 전처리됨)기법이 더 나을 것으로 사료된다. In order to evaluate the pre-treatment techniques for reduction and solubility, microwave, ozone, heat, alkali, ultrasonic, alkali-ultrasonic and alkali-ozone pre-treatment were investigated. Among the independent use of pre-treatment, alkali and ozone showed the highest reduction rate and solubility. In reduction rate, alkali pre-treatment was little higher than ozone pre-treatment. However, in solubility, ozone pre-treatment was little higher than alkali pre-treatment. Also, among the incorporative use of pre-treatment, alkali-ozone pre-treatment was the best pre-treatment for reduction and solubility. At 30 meq/L of NaOH and 0.32 gO₃/gSS, the reduction rate and solubility was 39.8%(VSS) and 41.6% respectively in batch test. In continuous test, the reduction and solubility was 10% lower than in batch test by alkali-ozone treatment. Moreover, incorporative use of alkali-ozone (ozone and alkali is pre-treated in one reactor) pre-treatment and alkali-ozone (after alkali treatment, ozone is used) pre- treatment showed the almost same reduction rate. However alkali-ozone (after alkali treatment, ozone is used) pre-treatment showed somewhat higher solubility. For the use of external carbon source of advanced wastewater treatment process and operation & management, incorporative use of alkali-ozone (ozone and alkali is pre-treated in one reactor) pre-treatment is thought to be better.

Cellular activities of osteoblast-like cells on alkali-treated titanium surface

박진우,이덕혜,여신일,박광범,최석규,서조영,Park, Jin-Woo,Lee, Deog-Hye,Yeo, Shin-Il,Park, Kwang-Bum,Choi, Seok-Kyu,Suh, Jo-Young The Korean Academy of Periodontoloy 2007 Journal of Periodontal & Implant Science Vol.37 No.2

임플란트와 골 사이의 결합력을 증가시키기 위하여 타이타늄 표면에 변화를 주기위한 많은 연구들이 진행되고 있다. 타이타늄의 표면 구조나 미세 지지도의 변화가 임플란트에 대한 세포의 반응에 영향을 미치며, 골아 유사세포는 표면 조도가 높은 타이타늄 표면에 더 잘 부착하며, 세포외 기질의 합성과 광물화 결정이 더 잘 일어난다고 알려져 있다. 그러나 대부분의 연구들은 마이크로 단위의 미세 지지도에 대한 연구들이고 나노 단위의 미세 지지도에 대한 연구들은 미미하다. 이에 본 연구에서는 ROS 17/2.8 cell line을 이용하여 기계적 처리만한 군을 대조군으로 하여 blasting 처리한 마이크로 단위의 미세 지지도 표면과 알칼리 처리된 나노 단위의 미세 지지도 표면에 대한 골아 유사세포의 세포 부착양상, 증식 그리고 골아 유사세포의 표식인자 발현양상 등을 상호 비교하여 골아 유사세포에 미치는 영향을 관찰하고자 하였다. SEM을 이용한 미세 지지도 관찰에서 알칼리 처리군에서는 약 200mm의 초미세 다공성의 양상을 나타내었고, blasting 처리한 군에서는 $10\;{\mu}m$ 이하의 움푹 파인 양상을 보였다. 표면조도 측정에 있어서는 blasting 처리한 군에서 기계적 처리와 알칼리 처리된 군보다 더 높은 표면 조도를 보였으며 이는 통계학적으로 유의한 차이를 나타내었다 (p<0.01). 표면결정성 분석에서는 알칼리처리 군에서 anatase와 rutile결정형이 보였으나, blasting 처리한 군과 기계적 처리 군에서는 관찰되지 않았다. 골아 유사세포 1시간 배양 후의 전자현미경 관찰에서 모든 군의 세포는 부착 및 전개 과정을 보였고, 3시간 배양에서는 모든 군의 세포가 더 많이 전개되었으나, blasting 처리한 군과 알칼리처리 군에서 세포가 다소 더 불규칙한 형태를 나타내었다. 24시간 배양에서는 모든 군의 세포에서 완전히 전개가 일어난 양상을 보였다. 1, 4, 7일간 세포배양 후 세포활성을 평가하기 위한 MTT assay에서는 모든 군에서 시간이 증가함에 따라 세포수가 증가하였으며, 1일째에 blasting 처리한 군과 알칼리처리 군에서 기계적 처리 군에 비해 세포활성도가 통계학적으로 유의한 증가를 보였다(p<0.01). 골아 유사세포 표식인자인 osteopontin, alkaline phosphatase, ${\alpha}\;1(1)$ collagen의 유전자 발현양상을 관찰해 본 결과, osteopontin, alkaline phosphatase, ${\alpha}\;1(1)$ collagen의 유전자 발현양상이 세 군 모두에서 유의한 차이는 관찰할 수 없었으나, blasting 처리한 군과 알칼리처리 군에서 기계적 처리 군에 비해 유전자 발현양상이 다소 증가하는 경향을 보였다. 결론적으로 blasting 처리한 마이크로 단위의 미세 지지도 표면과 알칼리 처리된 나노 단위의 미세 지지도 표면이 기계적 처리 군에 비해 골아 유사세포의 기능을 촉진시키나, 알칼리 처리된 나노 단위의 미세 지지도 표면은 blasting 처리한 마이크로 단위의 미세 지지도 표면이 골아 유사세포의 기능에 미치는 영향을 압도하지는 않는 것으로 사료된다. To improve osseointegration at the boneto-implant interface, several studies have been carried out to modify titanium surface. Variations in surface texture or microtopography may affect the cellular response to an implant. Osteoblast-like cells attach more readily to a rougher titanium surface, and synthesis of extracellular matrix and subsequent mineralization were found to be enhanced on rough or porous coated titanium. However, regarding the effect of roughened surface by physical and mechanical methods, most studies carried out on the reactions of cells to micrometric topography, little work has been performed on the reaction of cells to nanotopography. The purpose of this study was to examme the response of osteoblast-like cell cultured on blasted surfaces and alkali treated surfaces, and to evaluate the influence of surface texture or submicro-scaled surface topography on the cell attachment, cell proliferation and the gene expression of osteoblastic phenotype using ROS 17/2.8 cell lines. In scanning electron micrographs, the blasted, alkali treated and machined surfaces demonstrated microscopic differences in the surface topography. The specimens of alkali treatment had a submicro-scaled porous sur-face with pore size about 200 nm. The blasted surfaces showed irregularities in morphology with small(<10 ${\mu}m$) depression and indentation among flatter-appearing areas of various sizes. Based on profilometry, the blasted surfaces was significantly rougher than the machined and the alkali treated surfaces (p<O.01). On the x-ray diffraction analysis, anatase and rutile($TiO_2$) were observed on alkali treated surfaces, whereas not observed on machined and blasted surfaces. The attachment morphology of cells according to time was observed by the scanning electron microscope. After 1 hour incubation, the cells were in the process of adhesion and spreading on the prepared surfaces. After 3 hours, the cells on all prepared surfaces were further spreaded and flattened, however on the blasted and alkali treated surfaces, the cells exhibited slightly irregular shapes and some gaps or spaces were seen. After 24 hours incubation, most cells of the all groups had a flattened and polygonal shape, but the cells were more spreaded on the machined surfaces than the blasted and alkali treated surfaces. The MTT assay indicated the increase on machined, alkali treated and blasted surfaces according to time, and the alkali treated and blasted surfaces showed significantly increased in optical density comparing with machined surfaces at 1 day (p<0.01). Gene expression study showed that mRNA expression level of ${\alpha}\;1(I)$ collagen, alkaline phosphatase and osteopontin of the osteoblast-like cells showed a tendency to be higher on blasted and alkali treated surfaces than on the machined surfaces, although no siginificant difference in the mRNA expression level of ${\alpha}\;1(I)$ collagen, alkaline phosphatase and osteopontin was observed among all groups. In conclusion, we suggest that submicroscaled surfaces on osteoblast-like cell response do not over-ride the one of the surface with micro-scaled topography produced by blasting method, although the microscaled and submicro-scaled surfaces can accelerate osteogenic cell attachment and function compared with the machined surfaces.

연구논문 : 알칼리와 열처리에 의한 면직물의 감즙염색 발색효과

김옥수 ( Ok Soo Kim ),장정대 ( Jeong Dae Jang ) 한국의류산업학회 2011 한국의류산업학회지 Vol.13 No.6

The purpose of this study is to improve the method of color developing with alkali solution as a promotor of color developing for feasible use. Cotton fabric was dyed with persimmon extract ranged with 0~3% alkali component with 5 types of strong to mild alkali solution. Heat treatment for color developing was applied to fabric dyed with persimmon extract and alkali mixing solution. Tests were carried out to analyze the change of surface color, △,Ea*b*, and water repellent of the dyed cotton fabric. The alkali mixing sample showed higher △,Ea*b* value than control one without alkali mixing on the base of dyed fabric due to high color developing by alkali in the initial step of dyeing process. As alkali concentration increased, deeper dark color appeared on the fabric. The fabric color was changed to more dark in the application of sodium hydroxide, sodium carbonate, potassium carbonate in the intial step of dyeing process but color was not changed by increased beating time. However, the fabric showed a slight dark color with sodium acetate and more color change than that of the fabric dyed with persimmon extract without alkali. Therefore, sodium acetate seemed to a suitable promotor for color developing in persimmon extract dyeing. Property of water repellent was showed after color developing by heating with low concentration of alkali treatment.

국내 쇄석골재를 사용한 모르타르 봉 및 콘크리트 각주 시험편의 알칼리-실리카 반응성 비교

김성권,윤경구,허인 한국도로학회 2012 한국도로학회논문집 Vol.14 No.5

PURPOSES: The purpose of this study is to compare the alkali-silica reactivity for mortar bar and concrete prism specimens using crushed aggregates of 5 types in Korea. And the alkali-silica reactivity for those aggregates are measured by chemical test method. METHODS: The alkali-silica reactivity for those aggregates was measured by chemical test method of KS F 2545, mortar-bar test of KS F 2546, accelerated mortar-bar test method of ASTM C 1260 and concrete prism test method of ASTM C 1293, relatively. RESULTS : The alkali-silica reactivity for those aggregates was verified by chemical test of KS F 2546 and accelerated mortar-bar test of ASTM C 1260. However, it was not by mortar-bar test of KS F 2546 and concrete prism test of ASTM C 1293. CONCLUSIONS: The above results showed that relationship among the four test methods were very low. The results from 3 types of test methods using cement-aggregate combinations appeared to be different. Because the environmental conditions of test methods for measuring the alkali-silica reactivity such as equivalent alkali content(external source), humidity, temperature, and times were different though the aggregates were same. Moreover, alkali-silica reactivity showed the biggest impact when alkalis were supplied form outside and exposed to environmental conditions. The accelerated mortar-bar test method seems to be most appropriate test method for concrete structures exposed to alkali environment.

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.

알칼리 활성 고로슬래그 미분말 모르터의 알칼리-실리카 반응에 관한 실험적 연구

김영수,문동일,이동운 한국건축시공학회 2011 한국건축시공학회지 Vol.11 No.4

The purpose of this study was to investigate the expansion of alkali-activated mortar based on ground granulated blast furnace slag containing reactive aggregate due to alkali-silica reaction. In addition, this study was particularly concerned with the behavior of these alkaline materials in the presence of reactive aggregates. The experimental program included expansion measurement of the mortar bar specimens, as well as the determination of the morphology and composition of the alkali-silica reaction products by using scanning electron microscopy(SEM), and energy dispersive x-ray(EDX). The experiment showed that while alkali-activated ground granulated blast furnace slag mortars showed expansion due to the alkali-silica reaction, the expansion was 0.1% at Curing Day 14, showing that it is safe. After the accelerated test, SEM and BEM analysis showed the presence of alkali-silica gel and rim around the aggregate and cement paste. According to the EDX, the reaction products decreased markedly as alkali-activated ground granulated blast furnace slag was used. In addition, for the substitutive materials of mineral admixture, a further study on improving the quality of alkali-activated ground granulated blast furnace slag is needed to assure of the durability properties of concrete. 연구의 목적은 반응성 골재를 함유한 알칼리 활성화 고로슬래그 미분말의 알칼리-골재반응으로 인한 팽창을 조사하기 위한 것이다. 또한 이 연구는 현재 존재하고 있는 반응성 골재와 알칼리 재료들의 거동과 관련하여 특별히 관여되어 지고 있다. 실험 방법은 EDS, SEM을 통하여 알칼리-실리카 반응 생성물의 구성이나 미세구조를 관찰하였으며알칼리-실리카 반응에 의한 모르터 바의 팽창정도를 측정하였다. 실험 결과에 따르면 알칼리-활성화된 모르터는 알칼리실리카 반응 때문에 팽창이 되었지만 14일 재령에서 0.1%의 팽창률을 나타내어 알칼리-실리카반응에 대하여 안전한것으로 나타났다. 그리고 촉진 실험 후 SEM과 BEM분석한결과 골재 주변과 시멘트 페이스트에 알칼리-실리카 겔 및띠 모양의 생성물이 나타난 것을 볼 수 있었다. EDX에 따르면 반응생성물이 알칼리 활성화 고로슬래그를 사용하였을경우 현격히 감소한 것을 볼 수 있다. 추가적으로 광물학적혼화재료의 대체 재료로써 콘크리트 내구성의 특성을 보증하기 위하여 알칼리 활성화 고로슬래그의 품질을 향상시키는 연구가 필요하다.

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.

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.

Synergetic Influence of Microcrystalline Quartz and Alkali Content in Aggregate on Deterioration of Concrete Railroad Ties Used for 15 Years in High-Speed Railways

전동호,유주안,김지환,윤세윤,배영훈,오재은 한국콘크리트학회 2023 International Journal of Concrete Structures and M Vol.17 No.1

This study investigated the deteriorations of precast prestressed concrete (PSC) ties that were used for 15 years in high-speed railways in Korea and its damaging mechanism. The collected PSC ties with longitudinal cracks on sides and map cracks on surfaces exhibited strength degradation. The deteriorations were likely related to alkali-silica reaction (ASR) and delayed ettringite formation (DEF) together, given that the presence of massive ettringite crystals and the decomposition of ASR gel were found from microstructural analyses. Although there were no typical reactive siliceous aggregates for ASR in this study, ASR cracks were generated in the PSC ties. This is because the aggregates in the PSC ties with cracks were potentially reactive, and its high alkali-silica reactivity was likely attributable to the presence of microcrystalline quartz, supplying reactive SiO2 to trigger ASR. Furthermore, the alkali content in aggregates was associated with the deterioration of the PSC ties. The alkali-bearing minerals in aggregates (i.e., alkali feldspars) likely supplied enough alkalis for ASR. Besides, micas in aggregates could promote ASR due to their porous structure, which helps easy water ingress.

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.