• Magazine of the Korea Concrete Institute
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• v.5 no.4
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• pp.145-155
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• 1993

The results of an experimental study on the manufacture and the mechanical properties of fiber reinforced fly ash$\cdot$lime$\cdot$gypsum composites are presented in this paper. 'The composites using fly ash, lime, and gypsum were prepared with various fibers (PAN-derived and Pitch-derived carbon fiber, alkali-resistance glass fiber) and a small amount of polymer emulsion-styrene butadiene rubber latex (SBR). As the test results show, the manufacturing process technology of fly ash$\cdot$lime$\cdot$gypsum composites was developed and its optimum mix proportions were successfully proposed. And the flexural strength and toughness of fiber reinforced fly ash$\cdot$lime $\cdot$gypsum composites were increased remarkably by fiber contents, but the compressive strength of the composites were influenced by the kinds fiber more than by the fiber contents. Also, the addition of a polymer emulsion to the composites decreased the bulk specific gravity, but the compressive and flexural strength, and the toughness of the composites were not influenced by it, but were considerably improved by increasing fiber contents.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.379-386
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• 2020

The present study examined the effect of bottom ash aggregate contents on the compressive strength gain and mechanical properties(modulus of elasticity and rupture and splitting tensile strength) of concrete. Main test parameters were water-to-cement ratio and bottom ash aggregate contents for replacement of natural sand. Test results showed that the 28-days compressive strength of concrete and mechanical properties normalized by the compressive strength tended to decrease with the increase in bottom ash fine aggregate content. When compared with fib 2010 model equations, bottom ash aggregate concrete exhibited the following performances: lower rates of compressive strength gain at early ages but greater rates at long-term ages; slightly higher measurements for modulus of elasticity and rupture; and lower measurements for splitting tensile strength.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.3
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• pp.129-140
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• 2013

Bottom Ash is industrial by-product from a thermoelectric power plant. An immense quantities of bottom ash have increased each year, but most of them is reclaimed in ash landfill. In this study, in order to raise recycling rate of Bottom Ash, it is suggested to cure Bottom Ash (BA) mixtures mixed with cement, lime, Fly Ash (FA), and oyster shell (OS). Mixtures of 5~20 % mixing ratio had been cured for 1, 3, 7, 14, and 28 days using sealed curing and air-dry curing method. Unconfined compressive strength test was conducted to determine strength and deformation modulus ($E_{50}$) change for mixtures as mixing ratio and curing day, water contents of mixtures were measured after test. As a result, strength and $E_{50}$ were increased as mixing ratio and curing days, but values and tendencies of them appeared in different as kind of mixture, mixing ratio, curing method, and curing days. The results showed the addition of cement, lime, Fly Ash, and oyster soil in Bottom Ash could improved strength and $E_{50}$ and enlarge its field of being used.

• Journal of Energy Engineering
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• v.23 no.3
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• pp.211-220
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• 2014

This study reports the formation characteristics of tar, ash and clinker due to a wood pellet grade and the performance analysis of wood pellet boiler in terms of the moisture contents change of the wood pellet. Tar was accumulated on the heating surface according to combustion of wood pellet, the ash was yielded on the floor of combustion chamber in a wood pellet boiler and the clinker was solidified at the burner due to combustion of the 3rd grade wood pellet. Especially, the moisture contents is important factor to define the grade. Wood of logging residues has a non-uniform moisture contents after the field process, yields of tar, ash and clinker are increased in case of combustion due to the high ash contents. For these reasons, emission of harmful compounds in the exhaust gas, decrease of boiler efficiency and the system operating errors are observed. In the performance analysis of wood pellet boiler in terms of the moisture contents change of the 1st grade wood pellet, the boiler efficiency was reduced by 27.08% with 6.6% moisture contents increase. The optimum moisture contents of wood pellet is needed to improve the boiler performance and efficiency.

• Journal of Environmental Science International
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• v.19 no.1
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• pp.105-114
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• 2010

The objective of the paper is to experimentally investigate the compressive strength of the concrete incorporating fly ash. Ordinary Portland cement(OPC). Water to binder ratio(W/B) ranging from 30% to 60% and curing temperature ranging from $-10^{\circ}{\sim}65^{\circ}C$ were also adopted for experimental parameters. Fly ash was replaced by 30% of cement contents. According to the results, strength development of concrete contained with fly ash is lower than that of plain concrete in low temperature at early age and maturity. In high curing temperature, the concrete with fly ash has higher strength development than that of low temperature regardless of the elapse of age and maturity. Fly ash can have much effect on the strength development of concrete at the condition of mass concrete, hot weather concreting and the concrete products for the steam curing.

• Journal of the Korean Ceramic Society
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• v.44 no.9
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• pp.489-495
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• 2007

Effects of ultrafinely ground ash on the rheological properties of cement paste were investigated. Also compressive strength development and setting time of ultrafine ash blended cement mortar were investigated in the study. A sample with silica fume was included for comparison. According to the results of ultra fine ash blended cement paste in the lower W/B ratio, the fluidity were high, and the setting time was a little retarded. And the compressive strength of ultrafine ash blended mortar was increased in the long term. In the case of hardened cement paste at 28 days, $Ca(OH)_2$ contents was decreased in order of control, ultrafine ash, silica fume blended cement due to difference of the pozzolanic reaction.

• Journal of Nutrition and Health
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• v.26 no.8
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• pp.974-981
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• 1993

The longitudinal changes on contents of calcium, phosphorous and magnesium of breast milk of 23 Korean lacto-ovo-vegetarians(primiparae=11, multiparae=12) at 0.5, 1, 2 and 3 months postpartum have been studied. The mean ash content of breast milk per 100ml was 0.21g in total lactating women(n=23), and it decreased significantly during lactation(p<0.05). The mean calcium, phosphorous and magnesium contents of breast milk per 100ml were 26.83mg, 14.01mg and 2.72mg, respectively. Body calcium and phosphorous contents decreased significantly during lactation(p<0.05), but magnesium content tended to increase during lactation. There were no significant differences in ash, calcium, phosphorous and magnesium contents between primiparae and multiparae. The ratio of calcium to phosphorus was about 1.95:1 in breast milk and 0.62 : 1 in maternal dietary intake. In calcium and phosphorous, no correlation was found between maternal dietary intake and the concentration in breast milk. This study suggests that the contents of calcium, phosphorous and magnesium in lacto-ovo-vegetarian breast milk are not different from the concentrations of those in non-vegetarian.

• Journal of Animal Environmental Science
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• v.5 no.1
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• pp.63-72
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• 1999

This study was carried out to improve utilization of fly ash. Each animal waste was mixed with fly ash and composted This compost used at forage crops with corn, rye and alfalfa to examine to examine the fertilized efficiency and investigated productivity of forage crops, composition of this copmost and effect of fly ash on soil characteristics and composition. Content of organic matte, P2O5, K2O, CaO, MgO, Mn and B at the soil, which is given fly ash, increased. After the test crops were harvested, pH of the soil was maintained about 7 and contents of organic matter, phosphoric aicd, K, Mg, and B was increased at the soil of used fly ash. As fly ash was mixed, each DM yield of corn and rye was increased 10∼13% and 14∼21% especially alfalfa was increased 35% at the soil which is mixed fly ash with cage layer manure. As fly ash was mixed, each Crude protein (CP) of corn and rye was increased 6∼17% and about 29%, especially, as fly and cage layer manure was mixed CP of alfalfa was increased 33%. In conclusion, as fly ash is mixed with anlmal waste and use at forage crops, It makes the soil good and improve the productivity of forage crops.

• Economic and Environmental Geology
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• v.21 no.1
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• pp.97-106
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• 1988

The purpose of this study is to collect basic data which are prerequisite for quantitative analysis of coal logging data. The study involves laboratory measurements of physical properties such as seismic velocities (P,S-waves), resitivity and density of domestic and imported foreign coals. The relationships between these properties were analyzed by using cross-plots. Correlation between the physical properties of coal and the results of chemical analysis (calorie, fixed carbon, ash, moisture, volatile matter and sulfur contents) was also studied to obtain ideas about coal quality analysis using logging data. Summarized results are as follows: 1. $V_P$ is exponentialy related to $V_S$. And the average value of $V_P$ is about l.8 times as large as $V_S$. 2. Since coal has very low density compared with surrounding sedimentary rocks, density logging is appeared to be the best method for identifying coal seams and evaluating their qualities. 3. For the case of domestic coals, the ash contents and calorie show a perfect inverse relationship. Since the density increases as increase of ash content with a well-defined functional form, the ash content of domestic coals can be estimated by density measurements. 4. Because of low ash content, low density and high resistivity, foreign coals and domestic lignites are easily distinguished from domestic coals.

• Particle and aerosol research
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• v.10 no.4
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• pp.131-136
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• 2014

The importance of waste treatments is increasing because of the lack of resources and environmental problems resulted from economic growth policy. Especially, the pollutant dust which is one of the wastes should be treated considerately because it could cause secondary damages on the human health as well as environmental systems. Recently, massive amount of coal fly-ash is being produced in thermoelectric power plants. In this study, we compared two general methods used in estimating the amount of unburned carbon in fly-ashes to categorize the coal fly-ashes into several groups following their carbon contents. One is the "loss on ignition(KS L 5405) method" which estimates the change of mass after combustion, and it is generally used. Another one is measuring $CO_2$ gas content by burning solid carbon in the fly-ash, and it is called "$CO_2$ analysis method."