• Advances in concrete construction
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• 제11권3호
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• pp.207-217
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• 2021

This study relates to a production of Quaternary Cement Concrete (QCC) prepared by using Micro Silica (MS), Marble Dust (MD) and Rice Husk Ash (RHA), followed by an investigation towards fresh and hardened properties of blended concrete. A total of 39 mixes were cast by incorporating different percentages of MS (6%, 7% and 8%), MD (5%, 10% and 15%) and RHA (5%, 10%, 15% and 20%) as partial replacement of Ordinary Portland Cement. The workability of fresh concrete was maintained in the range of 100±25 mm by adding 0.7% of Super Plasticizer in the mix. Optimum mechanical strength was observed at combination of 8% MS+5% MD+10% RHA. Marble dust replacement from 10 to 15% and Rice husk ash replacements from 15 to 20% depicted a substantial reduction in compressive strength at all ages. Durability parameter with respect to water absorption at 28 days shows an increasing trend as the percentage of blending increases.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.379-382
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• 2005

Ocher block has started to be studied recently as a new environment friendly alternative building material. This article investigates the use of Rice Husk Ask (RHA) as an additive to improve properties of the ocher block. Ocher mixtures incorporating various proportions of RHA were compared. Compressive strength at various ages of these ocher blocks was evaluated ad the resistance to wet environment was also examined. These test result help to determine the effect of RHA on such properties of the ocher block as compaction, mix proportion, compressive strength and water absorption indexes. Based on these results, the new alternative building material and low cost construction techniques might be developed through more intensive research efforts.

• 한국가금학회지
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• 제33권1호
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• pp.65-80
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• 2006

재는 가축분을 중성화 시키며 토양에 산포하면 악취를 저감시키는 역할을 하며 하천에서 P의 양을 감소시킬 수 있다. 그러므로 본 연구에서는 재의 특성과 이들의 첨가가 가져올 환경적인 이용에 관해서 언급하였다. 재는 아직도 물리적 화학적으로 일정한 정의가 없다 (석탄재-CFA, 목재재-WA, 왕겨재-RHA). 이들 재를 형성하고 있는 조건과 조성에 따라 산도는 6.0이하 그리고 12.5이상까지 이른다. CFA를 분중에 첨가하면 분중에 녹아있는 P의 양이 감소되어 토양에 산포하면 수질을 향상시킨다. WA는 WA 자체에 많은 탄소 원자를 갖고 있기 때문에 분에서 발생하는 냄새를 제거할 수 있다. RHA는 재중에 $20{\sim}60%$ 가량이 실리카이다. 현재까지 CFA, WA 그리고 RHA를 토양에 산포하여 미치는 영향에 대한 연구는 많이 되어 있으므로 앞으로 가축분에 첨가하면 분중의 P과 악취를 낮출 수 있는 연구가 필요하다.

• Advances in environmental research
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• 제1권1호
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• pp.83-96
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• 2012

The water sludge is generated from the treatment of water with alum. Disposing of sludge again to the streams raises the concentrations of aluminum oxides in water, which has been linked to Alzheimer's disease. The use of water treatment plant (WTP) sludge in manufacturing of constructional elements achieves both the economical and environmental benefits. Due to the similar mineralogical composition of clay and WTP sludge, this study investigated the complete substitution of brick clay by sludge incorporated with some of the agricultural and industrial wastes, such as rice husk ash (RHA) and silica fume (SF). Three different series of sludge to SF to RHA proportions by weight were tried, which were (25: 50: 25%), (50: 25: 25%), and (25: 25: 50%), respectively. Each brick series was fired at 900, 1000, 1100, and $1200^{\circ}C$. The physical and mechanical properties of the produced bricks were then determined and evaluated according to Egyptian Standard Specifications (E.S.S.) and compared to control clay-brick. From the obtained results, it was concluded that by operating at the temperature commonly practiced in the brick kiln, a mixture consists of 50% of sludge, 25% of SF, and 25% of RHA was the optimum materials proportions to produce brick from water sludge incorporated with SF and RHA. The produced bricks properties were obviously superior to the 100% clay control-brick and to those available in the Egyptian market.

• Computers and Concrete
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• 제23권6호
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• pp.433-444
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• 2019

As rice husk ash (RHA) is not produced in controlled manufacturing process like cement, its properties vary significantly even within the same lot. In fact, properties of Rice Husk Ash Based Concrete (RHABC) are largely dictated by uncertainty leading to huge deviations from their expected values. This paper proposes a Robust Cost Optimization (RCO) procedure for RHABC, which minimizes such unwanted deviation due to uncertainty and provides guarantee of achieving desired strength and workability with least possible cost. The RCO simultaneously minimizes cost of RHABC production and its deviation considering feasibility of attaining desired strength and workability in presence of uncertainty. RHA related properties have been modeled as uncertain-but-bounded type as associated probability density function is not available. Metamodeling technique is adopted in this work for generating explicit expressions of constraint functions required for formulation of RCO. In doing so, the Moving Least Squares Method is explored in place of conventional Least Square Method (LSM) to ensure accuracy of the RCO. The efficiency by the proposed MLSM based RCO is validated by experimental studies. The error by the LSM and accuracy by the MLSM predictions are clearly envisaged from the test results. The experimental results show good agreement with the proposed MLSM based RCO predicted mix properties. The present RCO procedure yields RHABC mixes which is almost insensitive to uncertainty (i.e., robust solution) with nominal deviation from experimental mean values. At the same time, desired reliability of satisfying the constraints is achieved with marginal increment in cost.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1999년도 Proceedings of the 1999 Annual Conference The Korean Society of Agricutural Engineers
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• pp.294-300
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• 1999

After researching the physical properties of the concrete included Rice Husk Ash(RHA concrete) and workability of fresh concrete admixed RHA, we have tested durability of RHA-concrete against freeaing and thawing in the winter using rapid freezing and thawing test method(KS F 2456) . There aretwo hypotheses to explain the failure mechanism of a freezing and thawing action. First, the hydraulic pressure in the pores of freezing concrete make an internal stress of concrete structures outbreaking micro crack in the face of concrete, Second, Frost action causing damage to cement paste repeatedly come from soil frost action, freezing water in the capillaries. Initial Relative Dynamic Modulus of Elasticity (DME) was biggest in cae of unit binder weight 600kgf/㎥ and relative dynamic modulus of elasticity increased until 300cycles. In general , initial relative DME was proportional to unit binder weight . Relative DME was decreased in proportion to unit binder weight in the case of 300, 400, 500kgf/㎥ , but relative DME fo the others remained more than 90% until 300 cycles. It was not good effect of intermixed RHA to concrete in case of below unit binder weight 300kgf/㎥ and the resistance of freezing and thawing was not good either.

• Computers and Concrete
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• 제19권4호
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• pp.435-442
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• 2017

In recent years, the use of supplementary cementing materials, especially in addition to concrete, has been the subject of many researches. Rice husk ash (RHA) is one of these materials that in this research, is added to the roller compacted concrete as one of the pozzolanic materials. This paper evaluates how different contents of RHA added to the roller compacted concrete pavement specimens, can influence on the strength and permeability. The results are compared to the control samples and determined optimal level of RHA replacement. As it was expected, RHA as supplementary cementitious materials, improved mechanical properties of roller compacted concrete pavement (RCCP). Also, the application of adaptive neuro-fuzzy inference system (ANFIS) in predicting the permeability and compressive strength is investigated. The obtained results shows that the predicted value by this model is in good agreement with the experimental, which shows the proposed ANFIS model is a useful, reliable, fast and cheap tool to predict the permeability and compressive strength. A mean relative error percentage (MRE %) less than 1.1% is obtained for the proposed ANFIS model. Also, the test results and performed modeling show that the optimal value for obtaining the maximum compressive strength and minimum permeability is offered by substituting 9% and 18% of the cement by RHA, respectively.

• 한국산학기술학회논문지
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• 제18권4호
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• pp.111-117
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• 2017

이 연구는 제조 공정에 따른 국산 왕겨재의 재료특성 변화를 조사하는 것과 고강도 콘크리트 혼화재로서의 활용 가능성을 검토하는 것을 목적으로 수행되었다. 이를 위해 왕겨재의 소성온도 ($400^{\circ}C$, $650^{\circ}C$ 그리고 $900^{\circ}C$) 및 분쇄 여부를 주요 변수로 두고 그것의 입도 분포, 구성 성분, 그리고 미세구조가 분석되었다. X-ray fluorescence (XRF)를 이용한 성분 분석 결과, $650^{\circ}C$ 이상의 고온소성 공정을 거칠 경우, 왕겨재의 산화규소($SiO_2$) 함량이 92% 이상으로 향상되는 것을 확인하였다. 또한, 주사 현미경 촬영을 통해 $650^{\circ}C$ 에서 소성된 왕겨가 다공성 구조인 것을 확인하였으며, 이 공정이 적용된 시편의 흡습성능이 모든 시편들 중 가장 우수하였다. 분쇄 공정 적용시 공극구조가 파괴되기 때문에 흡습능력은 더 감소하는 경향을 보였다. 반면, $900^{\circ}C$ 에서 소성된 시편은 공극구조가 발견되지 않았고, 흡수율 역시 가장 낮게 나타났다. 분석결과를 근거로, $650^{\circ}C$ 에서 소성된 왕겨재는 포졸란 반응 활성화제 뿐만 아니라 흡습성능에 의한 자기수축 저감제로서 고강도 콘크리트를 위한 혼화재로서 적합한 것으로 결론 내려진다.

• Advances in concrete construction
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• 제11권1호
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• pp.81-88
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• 2021

Rice Husk Ash (RHA) geopolymer paste activated by sodium aluminate were characterized by X-ray diffractogram (XRD), scanning electron microscope (SEM), energy dispersion X-Ray analysis (EDAX)and fourier transform infrared spectroscopy (FTIR). Five series of RHA geopolymer specimens were prepared by varying the Si/Al ratio as 1.5, 2.0, 2.5, 3.0 and 3.5. The paper focuses on the correlation of microstructure with hardened state parameters like bulk density, apparent porosity, sorptivity, water absorption and compressive strength. XRD analysis peaks indicates quartz, cristobalite and gibbsite for raw RHA and new peaks corresponding to Zeolite A in geopolymer specimens. In general, SEM micrographs show interconnected pores and loosely packed geopolymer matrix except for specimens made with Si/Al of 2.0 which exhibited comparatively better matrix. Incorporation of Al from sodium aluminate were confirmed with the stretching and bending vibration of Si-O-Si and O-Si-O observations from the FTIR analysis of geopolymer specimen. The dense microstructure of SA2.0 correlate into better performance in terms of 28 days maximum compressive strength of 16.96 MPa and minimum for porosity, absorption and sorptivity among the specimens. However, due to the higher water demand to make the paste workable, the value of porosity, absorption and sorptivity were reportedly higher as compared with other geopolymer systems. Correlation regression equations were proposed to validate the interrelation between physical parameters and mechanical strength. RHA geopolymer shows comparatively lower compressive strength as compared to Fly ash geopolymer.

• Advances in concrete construction
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• 제12권5호
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• pp.429-437
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• 2021

In the era of building engineering the intensification of Self Compacting Concrete (SCC) is world-shattering magnetism. It has lot of rewards over ordinary concrete i.e., enrichment in production, cutback in manpower, brilliant retort to load and vibration along with improved durability. In the present study, the mechanical strength of CM-2 (SCC containing 10% of rice husk ash (RHA) as cement replacement and 600 grams of glass fibers per cubic meter) was investigated at various dosages of cement replacement by fly ash (FA) and GGBS. A total of 17 SCC mixtures including two control SCC mixtures (CM-1 and CM-2) were developed for investigating fresh and hardened properties in which, ten ternary cementitious blends of SCC by blending OPC+RHA+FA, OPC+RHA+GGBS and five quaternary cementitious blends (OPC+RHA+FA+GGBS) at different replacement dosages of FA and GGBS were developed with reference to CM-2. For constant water-cement ratio (0.42) and dosage of SP (2.5%), the addition of glass fibers (600 grams/m³) in CM-1 i.e., CM-2 shows lower workability but higher mechanical strength. While fly ash based ternary blends (OPC+RHA+FA) show better workability but lower mechanical strength as FA content increases in comparison to GGBS based ternary blends (OPC+RHA+GGBS) on increasing GGBS content. The pattern for mixtures appeared to exhibit higher workablity as that of the concentration of FA+GGBS rises in quaternary blends (OPC+RHA+FA+GGBS). A decrease in compressive strength at 7-days was noticed with an increase in the percentage of FA and GGBS as cement replacement in ternary and quaternary blended mixtures with respect to CM-2. The highest 28-days compressive strength (41.92 MPa) was observed for mix QM-3 and the lowest (33.18 MPa) for mix QM-5.