Hydration, Strength and pH Properties of Porous Concrete Using Rice Husk Ash

Kim, Young-Ik,Sung, Chan-Yong The Korean Society of Agricultural Engineers 2007 한국농공학회논문집 Vol.49 No.3

This study was performed to evaluate void ratio, compressive and flexural strengths, and pH properties according to the content ratio of rice husk ash, aggregate size, and neutral treatment time of porous concrete with content of rice husk ash produced as an agricultural by-product. The SEM results for cement mortar with a 5% rice husk ash for the weight of cement formed more C-S-H hydrates due to the $SiO_2$ of rice husk ash. In the XRD test, cement mortar with a 5% rice husk ash for the weight of cement registered a higher peak point of approximately $2{\theta}=20{\sim}25^{\circ}$ compared to cement mortar without rice husk ash. According to the results of the XRD and SEM tests, the $SiO_2$ that was a major chemical element of rice husk ash generated a large amount of calcium hydroxide in the early stage of the hydration process of cement leading to the formation of ettringite. The void ratio of porous concrete with rice husk ash decreased with increasing content ratio of rice husk ash. In addition, the void ratio of porous concrete with rice husk ash decreased compared to porous concrete without rice husk ash. The compressive and flexural strength of porous concrete with a 5% and 10% content ratio of rice husk ash slightly increased compared to concrete without rice husk ash. The pH value of porous concrete rapidly decreased immediately after neutral treatment. Then, it gradually increased and decreased again after 14 days. However, the pH value was nearly the same regardless of neutral treatment time in 28 curing days. Also, for neutral treatment, the pH value of porous concrete showed appropriate pH levels (less than 9.5) in all mixtures for planting at 28 curing days.

왕겨/모래/왕겨 회재의 유동 및 혼합 특성 연구

김보화 ( Bo Hwa Kim ),서명원 ( Myung Won Seo ),국진우 ( Jin Woo Kook ),최희망 ( Hee Mang Choi ),라호원 ( Ho Won Ra ),윤상준 ( Sang Jun Yoon ),문태영 ( Tae Young Mun ),김용구 ( Yong Ku Kim ),이재구 ( Jae Goo Lee ),이영우 ( Young Wo 한국화학공학회 2016 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.54 No.4

Lab-scale 기포유동층 반응기(D=0.1 m, H=1.5 m)에서 왕겨와 모래를 혼합하여 가스화를 통해 합성가스를 얻고 남은 왕겨 회재는 고부가가치 물질로 사용하기 위한 연구의 선행연구로서 왕겨/ 유동사/ 왕겨 회재(실리카)의 혼합 및 유동 특성을 규명하였다. 왕겨/유동사를 5:95, 10:90, 20:80, 30:70의 부피비로 유속 범위(0~0.63 m/s)조건으로 수행하였으며, 또한 왕겨 회재는 왕겨를 기준으로 부피비 6%로 결정하였다. 왕겨/유동사, 왕겨/유동사/왕겨 회재의 혼합실험을 통해 왕겨 부피비 0%, 5%, 10%에서는 최소유동화속도가 0.19~0.21m/s임을 확인하였고, 20%일때는 0.3m/s로 증가하였으며, 30%일때는 분리현상이 나타나 최소유동화속도가 측정 되지 않았다. 또한, 실험데이터에 따라 Brereton과 Grace의 mixing index를 이용하여 각 조건 별로 mixing index값을 도출한 결과 왕겨/유동사의 혼합은 0.8~1, 왕겨/유동사/왕겨 회재의 혼합은 0.88~1 사이임을 확인하였다. 이를 통하여 왕겨/유동사의 혼합과 왕겨/유동사/왕겨 회재 혼합의 최적 조업조건을 도출할 수 있었으며, 운전조건을 결정할 수 있었다. We investigate fluidization characteristics of the mixture of rice husk, silica sand and rice husk ash as a preliminary study for valuable utilization of rice husk ash obtained from gasification of rice husk in a fluidized bed reactor. As experiment valuables, the blending ratio of rice husk and sand (rice husk: sand) is selected as 5:95, 10:90, 20:80 and 30:70 on a volume base. Rice husk ash was added with 6 vol% of rice husk for each experiment and air velocity to the reactor was 0~0.63 m/s. In both rice husk/sand and rice husk/sand/ash mixture, the minimum fluidization velocity (Umf) is observed as 0.19~0.21 m/s at feeding of 0~10 vol.% of rice husk and 0.30 m/s at feeding of 20 vol.% of rice husk. With increasing the amount of rice husk up to 30 vol. %, Umf can not measure due to segregation behavior. The mixing index for each experiment is determined using mixing index equation proposed by Brereton and Grace. The mixing index of the mixture of rice husk/sand and rice husk/sand/ash was 0.8~1 and 0.88~1, respectively. The optimum fluidization condition was found for the good mixing and separation of rice husk ash.

식생 적용을 위한 왕겨재와 순환골재를 활용한 포러스 콘크리트의 공극률 및 강도 특성

김영익(Young-Ik Kim),성찬용(Chan-Yong Sung) 충남대학교 농업과학연구소 2006 농업과학연구 Vol.33 No.2

This study was performed to evaluate void ratio, compressive and flexural strength, and pH properties according to the admixture ratio of rice husk ash, aggregate size, and neutral treatment time of porous concrete with an admixture of rice husk ash produced as an agricultural by-product. The SEM results for cement mortar with a 5% rice husk ash admixture for the weight of cement formed more C-S-H hydrates due to the SiO₂ present in the applied rice husk ash. According to the results of the SEM test, the SiO₂ that was a major chemical element of rice husk ash generated a large amount of calcium hydroxide in the early stage of the hydration process of cement leading to the formation of ettringite. The void ratio of porous concrete with an admixture of rice husk ash decreased with increasing admixture ratio of rice husk ash. In addition, the void ratio of porous concrete with an admixture of rice husk ash decreased compared to porous concrete with no admixture of rice husk ash. The compressive and flexural strength of porous concrete with a 5% and 10% admixture ratio of rice husk ash slightly increased compared to concrete with no admixture of rice husk ash. The pH value of porous concrete rapidly decreased immediately after neutral treatment. Then, it gradually increased and decreased again after 14 days. Also, for neutral treatment, the pH value of porous concrete showed appropriate pH levels(less than 9.5) in all mixtures for planting at 28 curing days.

Lime-Fly Ash/Rice Husk Ash에 의한 해성 퇴적토의 강도특성 개선

민덕기,이경준,김현도 울산대학교 2001 공학연구논문집 Vol.32 No.1

본 연구에서는 울산광역시 남구 삼산동 일원의 지표 하 7m 지점에서 채취한 시료에 대하여 생석회 처리 후 FA(fly ash)와 RHA(rice husk ash)를 혼합하여 강도특성을 분석하였다. 연구방법으로는 채취한 시료와 혼합토에 대하여 기본물성시험과 일축압축강도 시험 및 C.B.R 시험을 실시하였다. 그리고 첨가재의 혼합에 따른 입자구조를 분석하기 위하여 주사전자현미경(SEM)을 이용하여 비교 · 검토하였으며, 첨가재의 화학적 구성성분을 X-선 형광분석(XRF)을 통하여 조사하였다. 화학성분 분석결과, FA의 주 구성성분은 Al2O3, Fe2O3가 약 50%, RHA의 경우는 SiO2가 약 91%를 차지하는 것으로 나타났다. 일축압축강도 시험결과, FA와 RHA가 각각 10% 첨가시 가장 큰 강도를 나타내었으며, 10% 이상 첨가시 강도가 저하되는 경향을 나타내었다. FA와 RHA가 각각 10% 첨가된 시료에 대한 C.B.R 시험결과에서 전자의 경우 118%, 후자의 경우 100%를 나타내었으며, 소성지수(PI)가 각각 9.4%, 9.1%값을 나타내어 소성지수 저감 후 보조기층, 기층재로써 사용이 가능할것으로 판단되었다. In this paper, a laboratory investigation was carried out to estimate the strength improvement of quicklime mixture with fly ash and rice husk ash for the effective use of surplus soils, and the shear strength with curing time was estimated at lime 10 percent with the change of fly ash and rice husk ash content. The effect of strength improvement has been established through the change of fly ash and rice husk ash content from the samples taken at Samsan region, Ulsan. The change in the microstructure of materials was investigated by using the scanning electron microscope(SEM). The chemical composition of materials was investigated by using the X-ray fluorescence spectrometer(XRF). The result of XRF analysis indicate that Al2O3 and Fe2O3 contents of fly ash is about 50%, SiO2 content of RHA is about 91%. The results of another tests indicated that the presence of lime with fly ash and rice husk ash encouraged the stabilization efficiency of lime with fly ash and rice husk ash, and increased shear strength. Furthermore, it is necessary for inquiring into the relationship between the characteristics of strength and the chemical components. Key words : fly ash, rice husk ash, quick1ime, surplus soils, SEM, XRF

Freeze-Thaw Resistance of Concrete using Acid-Leached Rice Husk Ash

박철우,Andres Salas,정철우,이창준 대한토목학회 2014 KSCE JOURNAL OF CIVIL ENGINEERING Vol.18 No.4

The main purpose of this research is to investigate the freeze-thaw resistance of concrete incorporating acid-leached rice husk ash. The research has been initiated because of its unique microstructural characteristic: rice husk ash maintains the original cellularstructure of rice husk that has large amount of empty space, so it has a potential possibility of reducing the air void spacing factor. Thefreeze-thaw resistance of concrete using rice husk ash is compared to that using silica fume. The result shows that the freeze-thawresistance of concrete using acid-leached rice husk ash is slightly less than that of silica fume concrete during 300 freeze-thaw cycles. When freeze-thaw cycles are extended to 600 cycles, freeze-thaw resistance of concrete using acid-leached rice husk ash isequivalent to the concrete using silica fume.

Methane adsorption by porous graphene derived from rice husk ashes under various stabilization temperatures

Che Othman Faten Ermala,Ismail Mohd Shafri,Yusof Norhaniza,Samitsu Sadaki,Yusop Mohd Zamri,Tajul Arifin Nur Fatihah,Alias Nur Hashimah,Jaafar Juhana,Aziz Farhana,Wan Salleh Wan Norharyati,Ismail Ahmad 한국탄소학회 2020 Carbon Letters Vol.30 No.5

The present work focused on the determination of texture, morphology, crystallinity, and gas adsorption characteristics of porous graphene prepared from rice husks ashes at diferent stabilization temperature. The stabilization temperature applied in this work is 100 °C, 200 °C, 300 °C, and 400 °C to convert rice husk into rice husk ashes (RHA). Chemical activation was adopted at temperature 800 °C using potassium hydroxide (KOH) as dehydrating agent at (1:5) impregnation ratio to convert RHA into rice husk ashes-derived graphene (GRHA). The resultant GRHA were characterized in terms of their morphologi�cal changes, SSA, crystallinity, and functional group with TEM, the BET method, Raman spectroscopy, and XRD analysis, respectively. Results from this study showed that the SSA of the GRHA at stabilization temperature 200 °C (1556.3 m2 /g) is the highest compared to the other stabilization temperature. Raman spectroscopy analysis revealed that all GRHA samples possess D, G, and 2D bands, which confrm the successful synthesis of the rice husks into porous graphene-like materials, known as GRHA. Appearance of difraction peak in XRD at 44.7° indicating the graphitic structure of all the GRHA sam�ples. Meanwhile, the TEM images of GRHA200 exhibited wrinkled structures due to the intercalation of oxygen and a few layers of graphene fakes. These wrinkled structures and graphene layers are the other factors that lead to the highest SSA of GRHA200 compared to other prepared samples GRHA. Furthermore, the adsorption capacity of CH4 for GRHA200 is up to 43 cm3 /g at 35 bar and ambient temperature, almost double the adsorption capacity performance of GRHA400 at the same operating pressure and temperature.

Durability Performance of Concrete using Rice Husk Ash

정의창,신상엽,김영수 한국건축시공학회 2013 한국건축시공학회지 Vol.13 No.2

The purpose of this study was to investigate the durability performance of concrete that includes rice husk ash. Chloride diffusion coefficient obtained through a rapid chloride penetration test and depth of CO2 penetration obtained through a rapid carbonation test were used to evaluate latent durability. Durability characteristics for rice husk ash replacement and age were determined. Through the experiment, it was found that when the replacement ratio of rice husk ash was increased from 0% to 10%, the compressive strength of concrete containing rice husk ash was similar to that of concrete containing silica fume. This shows that the durability performance of concrete containing rice husk is excellent compared to other concretes containing admixtures.

Durability Performance of Concrete using Rice Husk Ash

Jeong, Euy-Chang,Shin, Sang-Yeop,Kim, Young-Soo The Korean Institute of Building Construction 2013 한국건축시공학회지 Vol.13 No.2

The purpose of this study was to investigate the durability performance of concrete that includes rice husk ash. Chloride diffusion coefficient obtained through a rapid chloride penetration test and depth of $CO_2$ penetration obtained through a rapid carbonation test were used to evaluate latent durability. Durability characteristics for rice husk ash replacement and age were determined. Through the experiment, it was found that when the replacement ratio of rice husk ash was increased from 0% to 10%, the compressive strength of concrete containing rice husk ash was similar to that of concrete containing silica fume. This shows that the durability performance of concrete containing rice husk is excellent compared to other concretes containing admixtures.

소성왕겨 혼입 콘크리트의 철근부식저항성에 관한 연구

전정훈,김영수 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2

The purpose of this study is to analyze steel corrosion resistance of concrete containing rice husk ash, and the study deals with the properties of concrete blended the same ash. The specimens were made with normal portland cement and pozzolan materials with various replacement ratio and with W/B ratio ranging from 0.35 to 0.55. Compressive strength, coefficient of chloride diffusion, half cell potential, and corrosion area ratio were determinated for the test. The results show that the concrete with a lower W/B and pozzolan materials is superior resistant to chloride ions compared to the concrete a higher W/B and without pozzolan materials. It was observed that silica fume replacement ratio of 10% gives the best results with respect to chloride ion penetration and corrosion tests through cement-pozzolan concrete observed that rice husk ash replacement ratio of 10% gives the superior resistance compared to other rice husk ash replacement ratio and without replacement. Compressive strength is correlative relationship with charge passed.

코코넛 섬유 혼입률에 따른 RHA 및 OPC 콘크리트의 역학적 특성

이민희,권성준,박기태 한국구조물진단유지관리공학회 2015 한국구조물진단유지관리공학회 논문집 Vol.19 No.2

Currently, Eco-friendly construction materials are widely utilized for reducing CO2 emission in construction. Furthermore various engineering fibers are also added for improving a brittle behavior in concrete. In the paper, concrete specimens with 10% and 20% replacement ratio with RHA (Rice Husk Ash) are prepared, and engineering behaviors in RHA and OPC concrete are evaluated with different addition of coconut fiber from 0.125~0.375% of volume ratio. Several basic tests including compressive strength, tensile strength, flexural strength, impact resistance, and bond strength are performed, and crack width and deflections are also measured in flexural test. RHA is evaluated to be very effective in strength development and 0.125% of fiber addition leads significant improvement in tensile strength, ductility, and crack resistance. RHA and coconut fiber are effective construction material both for reutilization of limited resources and performance improvement in normal concrete. 건설분야에서 이산화탄소를 저감하기 위해 최근들어 친환경 혼화재료가 많이 사용되고 있다. 또한 콘크리트의 취성파괴를 보완하기 위해 다양한 섬유재의 사용이 고려되고 있다. 본 연구에서는 Rice Ash Husk를 10% 및 20% 치환한 콘크리트를 제조하였으며, 천연섬유 (코코넛 섬유)를 0.125%, 0.250%, 0.375% 혼입하면서 역학적 특성을 평가하였다. 평가를 위해 압축강도, 쪼갬인장강도, 휨강도, 내충격성, 부착강도 등이 평가되었으며, 휨부재의 하중에 따른 균열 및 변위를 분석하였다. RHA를 첨가한 콘크리트는 압축강도를 효과적으로 개선하였으며, 섬유재를 0.125%를 첨가하였을 때, 인장강도, 연성증가 그리고 균열저항성 등이 뚜렷하게 개선되었다. RHA 및 첨연섬유는 자원의 재활용 뿐 아니라 콘크리트의 성능도 개선할 수 있으므로 효과적인 건설재료라고 판단된다.