The quantities of low-grade reject fly ash (RFA) and paper sludge ash (PSA) generated are increasing annually and causing a serious social problem. In this study, the utility of these by-products was analyzed by using RFA and PSA as mineral admixtures. RFA-PSA blended mortar was fabricated and evaluated for use as a cement additive. RFA was milled to improve workability and the hydration reaction, and PSA was mixed with anhydrite to create the ettringite. As the RFA-PSA blended powder replaced 10% of the cement by weight, compressive strength of the mortar exceeded that of ordinary mortar prepared with Portland cement (OPC). Length change (28 days) of the RFA-PSA mortar with a 10% replacement rate was 68% of the OPC mortar and was 62% with a 30% replacement rate.

범지구적으로 다양한 문제를 야기하는 지구온난화 현상은 해결해야하는 필수 과제 중 하나로 여겨져 왔다. 이 중에서 이산화탄소는 낮은 지구온난화 지수에도 불구하고 가장 많은 양으로 인해 지구온난화 현상에 대해 가장 큰 책임을 가지고 있다. 이산화탄소 저감을 위한 기술로 금속 이온과 이산화탄소의 결합을 통한 무기탄산화 기술이 최근 떠오르고 있다. 무기탄산화 기술의 가장 큰 가능성 중 하나는 다양한 금속이온을 가지고 있는 폐기물을 원료로 이용할 수 있다는 점이다. 본 연구에서는 이러한 폐기물 중 다량의 Ca를 가지고 있는 것으로 알려진 비산재를 이용하여 무기탄산화, 그 중에서도 수용액 내에 이산화탄소를 주입하여 반응시키는 직접수성 탄산화를 통한 탄산칼슘 생성에 대해 다루었다. 다량의 불순물을 포함하고 있는 비산재를 보다 순수한 형태로 이용하기 위하여 고온 (70℃)의 물로 세정하여 이용하였다. 총 500 g의 흡수제 중 세정한 비산재가 10 wt% (50g) 포함되었고, 5 wt% (25 g)의 NaOH 첨가 유무에 따른 CO2 저감량의 차이를 CO2 로딩 분석을 통해 비교하였다. 생성물에 대하여 XRD 그리고 TGA 분석을 통해 구성성분 및 순도 분석을 진행하였다.

Geopolymer has recently emerged as an environmentally sustainable material considered to be an alternative to conventional Portland cement. Current study exhibits and discusses the results of experiment on the alteration in mechanical strength of fly ash-based geopolymer mortar activated by alkaline solution with three different sodium hydroxide solution concentrations (etc 10M, 14M and 18M) after exposure to elevated temperatures ranging from 100oC to 1000oC. Thegeopolymermotarexhibitedits strength increase after exposure at 100oC or 200oC ,followed bythe considerable strength loss in strength between 300oC and 700oC. However, the mortar strength rose slightly after exposure to temperature range from 800oC to 1000oC due to the viscous sintering process.

In this research, the adverse effect of various oils when the mortar including fly ash was submerged into the oils. From the experimental results, the highest length and mass changing rates were observed when the mortar was submerged into the biodiesel and in the case of relative dynamic elastic modulus, soy oil and biodiesel caused the most decreasing. Additionally, the mortar with fly ash was influenced more than ordinary Portland cement when it submerged into the oil.

Municipal solid waste incinerator (MSWI) fly ash was used for accelerated carbonation via bubbling of gaseous carbon dioxide (CO2) after treatment with sodium hydroxide (NaOH). The influence of alkaline concentration and volumetric flowrate of CO2 was investigated. Experimental results showed that carbonation reduced the leaching of Cu, Pb, Zn, and Cr. The pH of leachate decreased from around 12 to 10.5. The content of soluble chlorides was also decreased after carbonation. Additionally, the application of accelerated carbonation enhanced the sequestration of CO2 from MSW incineration plants. The TG/DSC analysis indicated that MSWI fly ash sequestrated approximately 185 g CO2/kg waste.

This study provides experimental results of pH restoration of acidified desulfurization seawater by the addition of the alkalinity enhanced seawater and additives (limestone and fly ash). The conservative seawater desulfurization processes use chemical solutions such as caustic soda (NaOH) or calcium hydroxide(Ca(OH)2). The method proposed in this study was aimed at reducing usage of chemicals. A control test was conducted to simulate the existing process without addition of the alkalinity-enhanced seawater and additives (limestone and fly ash). The pH of desulfurized seawater was increased by pH 5.84 through the conservative restoration process (i.e., adding raw seawater and NaOH solution followed by aeration). The 20%, 50%, and 80% of added raw seawater was replaced by the alkalinity-enhanced seawater. From the experimental result, 0.28, 0.89, and 1.05 m3/hr of 48% NaOH solution could be saved when applying the proposed method of the alkalinity enhanced seawater addition. When desulfurized seawater with pH 3.5 was mixed with raw seawater at a ratio of 1:1, the pH of seawater was increased up to pH 6. Therefore, the seawater restoration goal was set as pH 3.5. Experiments were conducted to increase pH of desulfurized seawater to pH 3.5 using additives (fly ash and limestone). Based on these results, the addition of fly ash and limestone to seawater was proved effective for pH restoration of desulfurized seawater.

이 논문은 표면 차수벽형 석괴댐(Concrete-Faced Rock-Filled Dam) 콘크리트의 내구성능 개선에 관한 것이다. 댐은 영구 구조물이 며 그 중요성을 감안할 때 충분한 내구성능이 확보되어야 한다. 이 논문에서는 플라이애시와 PVA 섬유를 혼입함으로써 차수벽 콘크리트의 내 구성능을 개선하고자 하였으며, 플라이애시와 PVA 섬유 혼입율에 따른 내구성능 향상 검증을 위하여 기본물성 (강도, 소성수축, 자기수축)을 포함한 내구성능 검증 실험(염소이온 침투, 마모 저항성, 동결융해 저항성)을 수행하였다. 실험 결과, 플라이애시 15%와 PVA 섬유 0.1%를 혼 입하였을 때 내구성능 개선 효과가 뛰어난 것으로 나타났다. 검증된 차수벽 콘크리트의 현장 적용을 통해 표면 차수벽형 석괴댐의 안전성 및 내 구성 개선에 기여할 수 있을 것으로 판단된다.

This study was evaluated the field applicability of high fluidity concrete for pc sleeper using high volume fly ash.

This paper investigated the thermal and mechanical properties of high-volume fly ash concrete for potential application in mass concrete.

The objective of this study is to investigate the potential use of MSW incineration fly ash as an economic material for the removal of heavy metals (Pb, Mn, Fe, and Cu) from AMD. Batch adsorption experiment was conducted to examine the effects of pH, adsorbent dosage and contact time on metal ions removal in synthetic AMD using MSW incineration fly ash. Precipitation of calcium hydroxide and sodium hydroxide was used for comparison with MSW incineration fly ash by adjusting the pH (5 ~ 11) by coagulation method with 20 min reaction time. Comparing the application of Ca(OH)2 and Na(OH), fly ash proves more efficient which may be due to its porosity and chemical composition. The results from adsorption studies showed that maximum adsorption rate was achieved at 0.4g dose when various fly ash dosages were added to the solution with 60 min optimum time and removal efficiency of heavy metals was over 96%. The effectiveness of fly ash can be related to its high calcium (CaO 55%) content. Efficiency of heavy metals removal was directly linked to the amount of fly ash in the reaction mixture and to the final pH attained. pH plays a significant role in heavy metal uptake. The main removal mechanism was adsorption at the surface of the fly ash together with the precipitation and co- precipitation from the solution with chemicals. Therefore the use of MSW incineration fly ash for treatment of AMD would represent a new market opportunity for this waste product. It can also be useful for neutralizing AMD and possibly reduce its adverse effects to the environment with efficient removal of metal ions from AMD.

Acid mine drainage (AMD) has emerged as one of the greatest environmental threats facing mining industry owing to its characteristic low pH, high acidity and elevated concentrations of metals and sulphate content. This study evaluates the efficiency of fly ash as a low cost material to remove heavy metals (Cu, Fe, Mn and Pb) from AMD. The effects of varying contact time, dosage and pH on adsorption were investigated using synthetically prepared AMD. The experiments was conducted in series of batches for adsorption using a mechanical shaker with 50mL AMD at various dosages of fly ash (0.1 - 0.8g/L) and coagulation using a standard jar tester of 1000mL AMD with chemical coagulant dosages (0.5 - 10g/L). Tests were also conducted with 50mL AMD without fly to evaluate the treatment efficiency of fly ash to chemicals. All tests were performed in duplicate for consistency and accuracy. The chemical composition of fly ash was characterized by X-ray fluorescence (XRF) and the result shows the fly ash is rich in calcium (CaO 54.9%). Leaching test of the fly ash was conducted using KLST and TCLP method to compare the results and evaluate the behavior of leaching ash in replenishing acidic media at low pH such as acid mine drainage. pH plays a significant role in heavy metal uptake in this study with increased in pH value the removal rate increased. The optimum dosage for Adsorption was found to be 0.4g/L with 60 min optimum contact time and coagulation 6mg/L with reduced metal concentrations much less than regulation standards for Cu, Fe, Mn and Pb. From all tests conducted fly ash proves more efficient with over 96% removal even at low dosages. The effectiveness of the treatment process will depend on the quality of the fly ash and the AMD. Therefore the use of fly ash for treatment of mine wastewater would represent a new market opportunity for this waste product. Recycling of fly ash will conserve the natural raw materials and abridge the disposal cost. It will also create new revenues and business opportunities while protecting the environment. Most significantly, the two waste products acid mine drainage and fly Ash could be neutralized and when reacted together to produce much cleaner water broadly compared to post process water derived from Lime treated AMD and sulfates removal rates were in the range of 90% in both experiments. Fly ash is more economical, sustainable.

This study investigated physcal properties of high performance concrete(HPC) using the garnet(GA) and Fly-ash(FA) under high temperature. After heating up the concrete, its appearance, failure mode, residual compressive strength, weight reduction ratio and other physical properties of concrete, it was mixed with nylon(Ny), polypropylene(PP), steel fiber(SF). The specimen was exposed to 100~800℃ and its crack control, spalling prevention and other physical characteristics were reviewed.

본 연구는 폴리머 기반 보수모르타르에 미분쇄된 플라이애시 치환율의 영향을 평가하였다. 주요변수는 양생온도와 미분쇄된 플라이애시의 치환율이다. 양생온도는 40℃, 20℃ 및 5℃로, 미분쇄된 플라이애시 치환율은 결합재 대비 0~35%로 변화하였다. 굳지 않은 모르타르에서는 플로우를, 굳은 모르타르에서는 재령별 압축강도, 응력-변형률 관계 및 탄성계수, 파괴계수를 측정하고, 주사전자현미경 및 엑스선회절기 분석을 수행하였다. 실험결과 보수모르타르의 플로우, 탄성계수 및 파괴계수는 미분쇄된 플라이애시 치환율 20~30%에서 가장 높은 성능을 발휘하였다. 또한 재령별 압축강도는 미분쇄된 플라이애시 치환율과 양생온도에 현저한 영향을 받았는데, 미분쇄된 플라이애시 치환율 20%에서 초기강도 발현율이 가장 높았다. ACI 209에서 제시하고 있는 콘크리트 재령별 압축강도예측모델에서 초기 및 장기재령 강도발현 계수는 미분쇄된 플라이애시 치환율과 양생온도의 함수로 일반화할 수 있었다. 미분쇄된 플라이애시가 첨가된 페이스트는 수화생성물을 나타내는 피크(peak)의 수와 강도(intensity)가 증가되고 플라이애시 입자주변에 CSH 겔이 형성되었다.

As a result of strength test on FA and BFS, FA concrete showed higher increase of strength compared to OPC, when FA4000 and FA5000 were mixed 30%, respectively. For BFS concrete, those mixed with 30% and 50% of BFS8000, respectively, showed higher or equivalent strength compare to OPC. As a result of test of chloride penetration on FA and BFS, diffusion coefficients of concrete mixed with 30% FA4000 and FA5000, respectively, showed to restrain average 6.5% of diffusion coefficient compared to OPC. And in case of BFS concrete, those mixed with BFS6000 and BFS8000, restrained diffusion of chloride ions 253% and 336%, respectively, compared to OPC. Therefore, Mixing 50% of BFS was most efficient in order to maximize restraint of chloride penetration according to metathesis of large amount.

This study examined dynamic and characteristics and chloride penetration of concrete mixed with large amount of FA and BFS, which are considered for positive application to construction fields with purpose of long-tern durability of concrete structures. As a result of strength test on FA and BFS, FA concrete showed higher increase of strength compared to OPC, when FA4000 and FA5000 were mixed 30%, respectively. For BFS concrete, those mixed with 30% and 50% of BFS8000, respectively, showed higher or equivalent strength compare to OPC. As a result of test of chloride penetration on FA and BFS, diffusion coefficients of concrete mixed with 30% FA4000 and FA5000, respectively, showed to restrain average 6.5% of diffusion coefficient compared to OPC. And in case of BFS concrete, those mixed with BFS6000 and BFS8000, restrained diffusion of chloride ions 253% and 336%, respectively, compared to OPC. Therefore, Mixing 50% of BFS was most efficient in order to maximize restraint of chloride penetration according to metathesis of large amount. For relation between compression strength and diffusion coefficient of FA and BFS concrete, as strength increased, diffusion coefficient decreased. In this study, when mixing FA and BFS to concrete for long-run durability and restraint against chloride penetration, for FA, mixing it to concrete with less or equivalent 30% of replacement rate was most efficient. And for BFS, as fineness was higher and mixing it to concrete with less or equivalent 50% of replacement rate, there were results of higher strength compared to OPC and more efficient restraint of chloride ions.

Zeolite was synthesized from power station waste, coal fly ash, as an alternative low-cost adsorbent and investigated for the removal of Sr(II) and Cs(I) ions from single- and binary metal aqueous solutions. In order to investigate the adsorption characteristics, the effects of various operating parameters such as initial concentration of metal ions, contact time, and pH of the solutions were studied in a batch adsorption technique. The Langmuir model better fitted the adsorption isotherm data than the Freundlich model. The pseudo second-order model was found more applicable to describe the kinetics of system. The adsorption capacities of Sr(II) and Cs(I) ions obtained from the Langmuir model were 1.7848 mmol/g and 0.7640 mmol/g, respectively. Although the adsorption capacities of individual Sr(II) and Cs(I) ions was less in the binary-system, the sum of the total adsorption capacity (2.3572 mmol/g) of both ions in the binary-system was higher than the adsorption capacity of individual ion in the single-system. Comparing the homogeneous film diffusion model with the homogeneous particle diffusion model, the adsorption was mainly controlled by the particle diffusion process.

The expansive behaviour of heat-cured mortars containing fly ash was investigated. The use of fly ash(replacement 20%) to the mortar reduced the long term expansion. But increase of SO3 in cement led to increase the long term expansion, and gave impetus to the formation of monosulphate for elevated temperature.

In this study, high performance fiber composites has developed using GGBS and Flyash with PVA fiber. Thus, four mixtures was determined accoding to the ratio of binder. A series of experiments, including slump flow, compressive strength, uniaxial tensile strength tests were carried out to characterize the mechanical properties of the fiber composites. The result of tests, slump flow showed an average 428mm and tensile strain 2% of behavior strain hardening of due to the occurrence multiple micro crack.

Geopolymer foam block was prepared and its characteristics discussed to evaluate the possibility of replacing blastfurnace slag (below BFS) with melting slag in this study. 10~20wt% of BFS was replaced with melting slag. And also10wt% of mine tailing was replaced with fly ash discharged from municipal solid waste incinerator (below MSWI). Thecompressive strength of foam block prepared was similar to that of foam block prepared without replacing BFS. Andalso it was increased by replacing 10wt% of mine tailing with MSWI fly ash. Considering these results, melting slagmay be used instead of BFS without damaging the quality of foam block.

In this study, it was evaluated air content properties of concrete using air-entraining agents for modified flyash.