• Advances in concrete construction
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• v.13 no.4
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• pp.315-325
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• 2022

Reinforced concrete structures are exposed throughout their lifetime to the phenomenon of carbonation, which considerably influences their durability by causing corrosion of the reinforcements. The fight against this phenomenon is usually ensured by anti-carbonation coatings which have the possibility of limiting the permeability to carbon dioxide or with coatings which absorb the CO₂ present in the air. A coating with good crack-bridging (sealing) capacity will prevent water from entering through existing cracks in concrete. Despite the beneficial effect of these coatings, their durability decreases considerably over time with temperature and humidity. In order to use coatings made from local materials, not presenting any danger, available in abundance in our country, very economical and easy to operate is the main objective of this work. This paper aim is to contribute to the formulation of a corrected dune sand-based mortar as an anti-carbonation coating for concrete. The results obtained show that the cement mortar based on dune sand formulated has a very satisfactory compressive strength, a very low water porosity compared to ordinary cement mortar and that this mortar allows an improvement in the protection of the concrete against the carbonation of 60% compared to ordinary cement mortar based on alluvial sand. Moreover, the formulated cement mortars based on dune sand have good adhesion to the concrete support, their adhesion strengths are greater than 1.5MPa recommended by the standards.

• Journal of Environmental Science International
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• v.33 no.1
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• pp.17-25
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• 2024

This study aimed to determine the most suitable coir substrate mixing ratio for optimizing the growth and yield of the "lpduelkkae 1" cultivar. We comprehensively analyzed the physicochemical properties, growth, and yields of four different substrate combinations: perlite (coir with mixing ratios of 70:30 (PC30), 50:50 (PC50), and 30:70 (PC70)) and 100% coir (C100). The results revealed substantial differences in substrate properties. C100 exhibited the highest total porosity and the lowest solid phase, indicating excellent air permeability. The pH levels and electrical conductivity (EC) values ranged from 5.4-6.8 and 1.2-3.1 dS·m^-1, respectively. Leaf growth parameters, including length, width, and dry weight, showed positive correlations with high coir ratios, except for PC30. PC70 and C100 outperformed other substrates in stem growth, exhibiting superior stem diameter and fresh and dry weights. The quantity of marketable leaves was the highest in the C100 substrate. Furthermore, C100 comprised integrated levels of essential nutrients, such as Ca and Mg, owing to its high coir content. In conclusion, a coir ratio of approximately 70% (v/v) should be maintained in the substrate for creating an optimal cultivation environment. Furthermore, the selection of humidity-resistant varieties as well as precise nutrient and moisture management for different seasons and growth stages are crucial for a successful perilla leaf hydroponic cultivation.

• Horticultural Science & Technology
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• v.32 no.2
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• pp.157-164
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• 2014

Objective of this research was to develop root media containing expanded rice hull (ERH) and carbonized rice hull (CRH). To achieve this, the physico chemical properties of two materials were analysed and blended with peatmoss (PM) or coir dust (CD) with various ratio. Based on the physical properties of the blended materials, 4 root media were selected for future experiment. After the analysis of pH and EC of the selected root media, the kinds and amount of pre-planting nutrient charge fertilizers (PNCF) incorporated into each root medium were varied, and then, final chemical properties of the root media were analysed. The total porosity (TP), container capacity (CC), and air-filled porosity (AFP) were 81.3%. 39.9%, and 41.4% in ERH and 77.6%, 64.1%, and 13.5% in CRH, respectively. The percentage of easily available water (EAW, from CC to 4.90 kPa tension) and buffering water (BW, 4.91-9.81 kPa tension) were 11.37% and 5.27%, in ERH and 17.26% and 14.28% in CRH, respectively. The pH of ERH was 7.1, but it was extremely high in CRH such as 11.2. The EC and CEC were $1.31dS{\cdot}m^{-1}$ and $12.1meq{\cdot}100g^{-1}$ in ERH and $6.53dS{\cdot}m^{-1}$ and CEC 7.79 $meq{\cdot}100g^{-1}$ in CRH, respectively. The ranges of TP, CC and AFP in 4 selected media (PM + ERH, 6:4, v/v; CD + ERH, 8:2; PM + CRH, 7:3; CD+CRH 6:4) were 89.2-90.3%, 67.3-81.8%, and 8.3-21.9%, respectively. The pHs and ECs in root media containing peatmoss such as PM + ERH (6:4) and PM + CRH (7:3) were 4.0-4.3 and $0.33-0.365dS{\cdot}m^{-1}$, whereas those of CD + CRH were 7.4-7.9 and $1.282dS{\cdot}m^{-1}$. The pHs and ECs, however, analysed before and after the incorporation of PNCF in each root medium were not significant different. This result indicated that the incorporated fertilizers in PNCF to adjust medium pH did not dissolve enough to influence medium pH, but it is very normal in root media containing dolomitic lime and sulfur powder in adjusting pH. The Information obtained in this study may facilitate an effective formulation of root media containing rice hulls.

• Journal of the Korean Electrochemical Society
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• v.6 no.1
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• pp.41-47
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• 2003

For the development of low temperature anode-supported planar solid oxide fuel cell, the planar anode supports with the thickness of 0.8 to 1 mm and the area of 25, 100 and $150\;cm^2$ were fabricated by the tape casting method. The strength, porosity, gas permeability and electrical conductivity of the planar anode support were measured. The porosity of anode supports sintered at $1400^{\circ}C$ and then reduced in$H_2$ atmosphere was increased from $45.8\%\;to\;53.9\%$. The electrical conductivity of the anode support was $900 S/cm\;at\; 850^{\circ}C$ and its gas permeability was 6l/min at 1 atm in air atmosphere. The electrolyte layer and cathode layer were fabricated by slurry dip coating method and then had examined the thickness of $10{\mu}m$ and the gas permeability of 2.5 ml/min at 3 atm in air atmosphere. As preliminary experiment, cathode multi-layered structure consists of LSM-YSZ/LSM/LSCF. At single cell test using the electrolyte layer with thickness of 20 to $30{\mu}m$, we achieved $300\;mA/cm^2$ and 0.6V at $750^{\circ}C$

• Korean Chemical Engineering Research
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• v.60 no.1
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• pp.116-124
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• 2022

In this study, waste air containing ethanol and hydrogen sulfide, was treated by an integrated hybrid system composed of two alternatively-operating UV/photocatalytic reactor-process and biofilter processes of a biofilter system having two units with an improved design (R reactor) and a conventional biofilter (L reactor). Both a pressure drop (△p) per unit process of the integrated hybrid system and a microbe-population-distribution of each biofilter process were observed. The △p of the UV/photocatalytic reactor process turned out very negligible. The △p of the L reactor was observed to increase continuously to 4.0~5.0 mmH₂O (i.e., 5.0~6.25 mmH₂O/m). In case of R reactor, its △p showed the one below ca. 16~20% of the △p of the L reactor. Adopting such microbes-carrying biofilter media with high porosity as waste-tire crumb media, and the improved biofilter design, contributed to △p of this study, reduced by ca. 37~50% and 40~53%, respectively, from the reported △p of conventional biofilter packed with biofilter media of the mixture (50:50) of wood chip and wood bark. In addition, the △p of R reactor in this study, reduced by ca. 80% from the reported △p of conventional biofilter packed with biofilter media of the mixture (75:25) of scoria with high porosity and compost, was mainly attributed to adopting the improved biofilter design. On the other hand, in case of L reactor, the CFU counts in its lowest column was analyzed double as much as those in any other columns. However, in case of R reactor, its CFU counts were bigger by 50% than the one of L reactor and its microbes were evenly distributed at its higher and lower columns of R_dn reactor and R_up reactor. This phenomena was attributed to an even moisture distribution of 50~55% of R reactor at its higher and lower columns. Therefore, R reactor showed superb characteristics in terms of both △p and microbe-population-distribution, compared to L reactor.

• Journal of Bio-Environment Control
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• v.21 no.3
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• pp.199-206
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• 2012

This study was conducted in a glasshouse to examine the possibility of producing tomato plug seedlings in a newly-developed inert phenolic foam medium. Plug seedlings of 'Madison' tomato were grown in four pellet type media, Grodan rockwool, UR rockwool, phenolic foam LC, and phenolic foam LC-lite. Seed germination was checked for 7 days. Seedling growth was measured at 19 days after sowing. The greatest germination was obtained in the phenolic foam LC and phenolic foam LC-lite. Plant height, hypocotyl length, leaf area, dry weight, and fresh weight were significantly greater in the rockwool medium than those in the other media. However, the T/R ratio and stem diameter were the greatest in the phenolic foam LC than those in the other media. The total porosity and container capacity of the phenolic foam LC was higher than in the other media. The air space (%) was lowest in the phenolic foam LC. Overall, the phenolic foam LC and phenolic foam LC-lite produced seedlings with similar growth as the rockwool. These results suggested that both phenolic foam LC and phenolic foam LC-lite have potential to be used in production of plug seedlings of 'Madison' tomato.

• Journal of the Korean Ceramic Society
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• v.53 no.2
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• pp.194-199
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• 2016

Presently, for the cement industry, studies that seek to reduce $CO_2$, because of the development of the plastic industry and demand for reduction of energy use, have been actively conducted among them, studies attempting to use Gamma-$C_2S({\gamma}-C_2S)$ to fix $CO_2$ have been actively conducted. The ${\gamma}-C_2S$ compound has an important function in reacting to $CO_2$ and stiffening through carbonatization in the air. The ${\gamma}-C_2S$ compound, reacting to $CO_2$ in the air, generates $CaCO_2$ within the pore structure of cement materials and densifies the pore structure this leads to an improvement of the durability and to the characteristic of resistance against neutralization. Therefore, in this experiment, in order to synthesize ${\gamma}-C_2S$, limestone sludge and waste foundry sands are used these materials are plasticized for 30 or 60 minutes at $1450^{\circ}C$, and are prevented from being cooled in the temperature range of $30{\sim}1000^{\circ}C$ when they are about to be cooled. XRD analysis and XRF analysis are used to determine the effects of this process on ${\gamma}-C_2S$ synthesization, the temperature at which a thing is plasticized, and the conditions for cooling that obtain in the plasticized clinker also, in order to confirm the $CO_2$ capture function, analysis of the major hydration products is conducted through an analysis of carbonatization depth and compressive strength, and through MIP analysis and XRD Rietveld analysis. As a result of these analyses, it is found that when ${\gamma}-C_2S$ was synthesized, the clinker that was plasticized at $1450^{\circ}C$ for one hour demonstrated the highest yield rate the sample with which the ${\gamma}-C_2S$ was mixed generated $CaCO_3$ when it reacted with $CO_2$ therefore, carbonatization depth and porosity were reduced, and the compressive strength was increased.

• The Journal of Natural Sciences
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• v.11 no.1
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• pp.131-135
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• 1999

The objective of this research was to improve moisture retention capacity of pine bark. To achieve this, barks were ground with Wiley mill of hammer mill and were blended with recycled rockwool. Then, changes of soil physical properties were determined. The percentage of particles larger than 5.6 mm was 86.5% in raw materials. The percentage of particles larger than 1 mm decreased and those of particles smaller than 1 mm increased by grinding with Wiley mill or hammer mill. Grinding with Wiley mill showed better effect than those of hammer mill in decreasing particle size distribution. Grinding resulted in decreased total porosity (TP) and air space (AS) and increased container capacity (CC) and residual water content (RW), indication improved moisture retention capacity. The material ground with Wiley mill, than blended with 50% recycled rockwool had 81.1%, 67.7%, 13.5% and 235 ml in TP, CC, AS and RW, respectively. These results indicated that moisture retention capacity was improved by blending with recycled rockwood, but aeration of root media was much better than those of peat+vermiculite(1:1, v/v), which is commonly used in commercial production.

• The Korean Journal of Mycology
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• v.3 no.1
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• pp.1-19
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• 1975

Since the importance of casing in fruit body formation of Agaricus bisporus has been emphasized, physico-chemical characteristics of casing materials were discussed by many workers and a mixture of peat and mineral soil as proper casing material has been adopted in many of mushroom growing countries. Because of limited resources of peat in Korea, it is necessary to find practical performance and substitutional materials for casing. The effect of casing on mycelial growth and mushroom yield of A. bisporus varied with materials, its combination and practices etc. The experiments to be discussed in this paper are concerned with pH and Ca of casing material which influence A bisporus, and changes of physico-chemical characteristics with mixing ratio of casing materials and its effect on A. bisporus. The optimum range of moisture content of each material, management of watering and application of physico-chemical characteristics casing materials was also investigated and re-use of weathered spent compost for casing material was described. 1. The effect of calcium on mycelial growth of A. bisporus at various pH in Halbschalentest showed different results with calcium sources. Best results were obtained around neutrality and fresh weight of fruit bodies grown in the range of pH 7 to 8 was highest among the tested levels. 2. Available moisture, pore space, organic matter, cation exchangeable capacity and exchangeable cation was increased by an increase of mixing ratio of peat in casing materials, while an adverse effect was obtained by addition of sand. 3. Mycelial growth on clay loam was more rapid at a lower bulk density of 0.75g/cc and at 20% moisture content on a dry weight basis at the same bulk density. 4. Mixing ratio of casing materials, 60 to 80 per cent by volume of peat mixed with 20 to 40 per cent of clay loam produced the highest yield of fresh fruit bodies and sand the lowest. However, per cent of open cap was highest in peat and lowest in sand. 5. Days required for fruit body initiation was shortened in mixtures of peat and clay loam by one to three days compared with other materials and the formation of flushes was clear. 6. The effect of some physico-chemical characteristics of casing materials on the fresh weight of fruit bodies were estimated by a multiple regression equation; Y=-923.86+$8.18X_1+8.04X_2+7.90X_3+0.12X_4+2.03X_5-0.82X_6-0.54X_7$ where $X_1,X_2,X_3,X_4,X_5,X_6,X_7$ are sand, silt, clay, available moistuer, porosity, organic matter and exchangeable cation respectively. The productivity of certain casing material could be predicted from this equation. 7. Fresh weight of fruit bodies was positively correlated with porosity exchangeable cation, organic matter, available moisture, silt and clay of materials; while sand was negatively correlated. On the contrary, sand was the unique factor reducing per cent of open cap. 8. Distribution of three phases of high productive casing material was concentrated in the range of 10 to 30 per cent solids, 15 to 30 per cent liquids, and 50 to 60 per cent in air volume. 9. Fresh weight of fruit bodies from peat was not affected with heavy watering but in clay loam and sandy loam severe crop losses occurred. Fresh weight of individual fruit was increased and open caps were decreased with heavy watering but light watering resulted in adverse effects: its effect was especially great in peat. 10. Optimum range of moisture content by weight on a dry basis was different with each casing material. To maintain optimum moisture content concerned with yield of fruit bodies and open cap, sandy loam and peat mixtures required daily watering of 0.6, 0.6 to 1. 2 and 1.2 to 2.4 liters per $3.3m^2$ of bed area, respectively. 11. Maximum yield of fruit body was recorded in the range of pF 2. 0 to 2. 5 of casing materials if organic matter content was below 4.2 per cent and in pF 1. 3 to 1.8 if above 7.1%. 12. pF curve of a certain casing material could be draws from moisture content at various pF values by multiple regression equations provided texture, organic matter and calcium of the casing material are given. Optimum moisture range of the casing materials also could be estimated by the equation. 13. It was possible to improve the phyico-chemical characteristics of clay loam and sandy loam by addition of weathered spent compost although the effect was less than in the case of peat. Fresh weight of fruit bodies wsa increased by addition of weathered spent compost but its effect was not as remarkable as peat. Accordingly, further studies will be required.

• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.362-371
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• 2012

Objective of this research was to secure the information on physical and chemical properties of peatmoss and coir dust. To achieve this, 6 kinds of peatmoss and 10 kinds of coir dust currently used in the country as the root medium components in plant factories were collected and analysed. The mean ${\pm}$ standard deviation (SD) of total porosity and container capacity in peatmoss and coir dust were $79.6{\pm}5.04$ and $83.6{\pm}6.18%$, and $69.9{\pm}10.17$ and $65.9{\pm}3.46%$, respectively. These indicate that peatmoss has higher water holding capacity than coir dust and the characteristics are highly varied among peatmoss. The 4 out of 5 kinds of peatmoss had lower than 10%, but coir dust had 12~26%, of air-filled porosity. The percentage of easily available water and buffering water in peatmoss and coir dust was 18~22 and 11~16% and 9~13 and 5.5~7.5%, respectively. These results indicate that precise irrigation is required when coir dust is used as the root medium. The ranges of pH and electrical conductivity (EC) were 3.46~4.17 and $0.137{\sim}0.253dS{\cdot}m^{-1}$ in peatmoss and 5.31~6.48 and $0.250{\sim}0.1.580dS{\cdot}m^{-1}$ in coir dust. However, $0.563{\pm}0.83dS{\cdot}m^{-1}$ in mean ${\pm}$SD of coir dust EC indicates that it is higher than that of peatmoss, and the coir dust are highly varied in EC. The cation exchange capacity of peatmoss was 3 to 4 times as high as that of coir dust. The coir dust had higher $NO_3$ and $PO_4$ and lower $NH_4$ than peatmoss. The K and Na concentrations in coir dust were extremely high indicating that these ions caused the rising in EC. The percentage of hot water and alkali extracts of peatmoss were 6.67~16.37 and 0~38%, whereas those of coir dust were 30.0~65.1 and 23.1~70.3%. These results mean that possible existence of growth inhibiting materials in coir dust.