• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2A
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• pp.177-184
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• 2010

This study was performed to determine the effects of filling materials on the physical properties of permeable polymer concrete. The filling materials were ground calcium carbonate, ground granulated blast furnace slag and fly ash. In this experiment, permeable polymer concrete mixtures with unsaturated polyester resin contents from 5 to 7 weight %, filler/resin ratio of 0~2.0 and crushed coarse aggregate passing 15 mm sieve were prepared and coefficient of permeability, void ratio, compressive strength and flexural strength were tested. As the test results, increase in the strength and decrease in the coefficient of permeability of the permeable polymer concrete were generally observed with increasing the resin contents and filler/resin ratio. The compressive and flexural strength of the permeable polymer concrete were in the range of 8.0 to 35.0 MPa and 2.0 to 9.0 MPa respectively and the highest strength was shown at the mixtures with 7 weight % unsaturated polyester resin contents, 2.0 ratio of filler/resin and filler of ground calcium carbonate. On the other hand, in the level of 20 MPa compressive strength, the mixtures with filler of fly ash was shown as the most economic permeable polymer concrete.

• Journal of the Korean Ceramic Society
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• v.39 no.3
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• pp.259-264
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• 2002

In this study, sintering properties of Artificial Lightweight aggregates(ALAs) prepared from coal ash as a function of sintering temperature (900$^{\circ}$C, 1000$^{\circ}$C, 1100$^{\circ}$C) and time (2min, 5min, 10min) when limestone added as lightweight mineral was investigated. Increasing the sintering temperature resulted simultaneously from a decline of quartz mineral as well as growth of mullite mineral. Addition of limestone to ALAs newly formed sintered minerals such as clinoptilolite and plagioclase. Sintering effect of ALAs prepared from coal ash and limestone was more affected by a sintering temperature than time. As sintering temperature and time increae, transition of macropore to micropore and formation of closed pores were happened, consequently shrank the total pore volume of ALAs. The surface of ALAs sintered at 1000$^{\circ}$C for 5min was nearly not detected open pores due toe amalgamation effect of molten slag layer but homogeneous distributions of closed pores with micro-scale were examined in cross sectional area ALAs. Sintering temperature and time which present the most adequate state, in the preparation of ALAs, are corresponded to 1000$^{\circ}$C and 5min, respectively.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.697-700
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• 2008

Recently, high strength, flowability, and durability of concrete were required according to increase of large scale and high rise structure. However, cracks occurred easily on the high performance concrete. In this reason, using expansion agent for reducing shrinkage cracks were increased, but it did not consider on durability of high performance concrete. Accordingly, this study1 investigated the resistance of shrinkage and damage form salt by mixing CSA expansion agent on the blast-furnace slag cement and mixed cement for the low heat of hydration by three components. The cases that 8% of expansion agent was mixed and the proportion was OPC were expanded till 43.7 times compared with control concrete. For the resistance to the damage of salt, it was improved when mixing ratio was incresed and the maximum size of coarse aggregate growed bigger. In this study, the resistance to the damage of salt of the cases that 8% of expansion agent was mixed was improved about 16% compared with control concrete.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.4
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• pp.51-59
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• 2007

Recently, concrete has been made porous and used for sound absorption, water permeation, vegetation and water purification according to void characteristics. Many studies are carried out on the utilization of sewage sludge, fly ash and waste concrete to reduce the environmental load. This study was performed to evaluate the void, strength, relationship between void and strength, permeability and chemical resistance properties of porous polymer concrete for pavement with different fillers. An unsaturated polyester resin was used as a binder, crushed stone and natural sand were used as an aggregate and bottom ash, fly ash and blast furnace slag were used as fillers. The mix proportions were determined to satisfy the requirement for the permeability coefficient, $1{\times}10^{-2}$ cm/s for general permeable cement concrete pavement in Korea. The void ratios of porous polymer concrete with fillers were in the range of $18{\sim}23%$. The compressive strength and flexural load of porous polymer concrete with fillers were in the range of $19{\sim}22$ MPa and $18{\sim}24$ KN, respectively. The permeability coefficients of porous polymer concrete with fillers were in the range of $5.5{\times}10^{-1}{\sim}9.7{\times}10^{-2}$ cm/s. At the sulfuric acid resistance, the weight reduction ratios of porous polymer concrete immersed during 8-week in 5% $H_{2}SO_{4}$ were in the range of $1.08{\sim}3.56%$.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.365-368
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• 2008

This research is related to 240MPa ultra-high strength concrete(UHSC) with extremely loss W/B ratio. For this development, High flow cement is mainly used which has a short reaction rate due to the high blaine and high early strength, which can make greater fluidity in case of very low W/C ratio. It made the best mixture using the mineral admixtures silica fume, slag powder and special admixture. For dispersibility and homogeneity of cement binder, cement of premix type is produced using omni-mixer. Moreover, it ensures the fluidity of ultra-high strength concrete(UHSC). For having a good fire performance, we made an experiment special coarse aggregate. As a result, we got 180MPa in case of water curing, 200MPa in case of steam curing and uniform UHSC of 240MPa in case of a special curing method.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.445-448
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• 2008

It is essential that concrete component is made up with aggregate, cement and water. But today, Public concern is increasing of a variety structure and ocean environmental, resource recycle. Also, According to heat of hydration rising, Concrete is make a causative of concrete-crack. Concrete-crack cause a falling-off in quality of concrete. consequently, High-performance concrete is evaluated by concrete material properties and carbonation resistance with different admixture(fixing fly-ash 20%), granulated blast furnace slag replacement ratio (30%, 45%) different W/B (26%, 30%, 34%) and XRD(X-ray Diffraction) analysis.

• Journal of Soil and Groundwater Environment
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• v.23 no.3
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• pp.43-50
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• 2018

In a previous study, the feasibility of four materials (bentonite, steelmaking slag, lime and organic compost) to induce soil aggregate formation was assessed and the mixtures of organic compost and lime were chosen as most effective amendments in terms of cost benefit. This work is a subsequent study to evaluate the effectiveness of those amendments in reducing soil loss in $15^{\circ}$ sloped agricultural area by using rainfall simulation test. Three different soils were treated with two conditions of organic compost/lime mixtures (2% + 2%, 3% + 1%, w/w). In the amended soils, soil fertility was increased due to the increase of CEC, T-N, and T-P. During the rainfall simulation, suspended solid in run-off water from amended soil were reduced by 43% ~ 78%. When the content of organic compost was higher than that of lime, reduction of soil loss was also increased by 67% ~ 78%. Sediment discharge was also decreased by 72% ~ 96% in the amended soil. Similar to the suspended solid analysis, higher organic compost content led to more reduction of soil discharging, which implies organic compost is more effective than lime in reducing soil loss. The overall result suggests that the mixtures of organic compost and lime could be used as amendment materials to reduce soil loss in sloped farmland.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.6
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• pp.247-257
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• 2021

This study was started to investigate why autoclave curing (AC) specimen showed an improvement in compressive strength after immersion in water for a long time, although AC specimen did not showed a high initial compressive strength unlike our expectations. Distilled water and alkaline solutions were used for immersion and three different curing methods were engaged. It was expected that the compressive strength would be improved after immersion in alkaline solutions; however, there was little difference in compressive strength after 21 day immersion because both new crystallites produced by additional geopolymerization and expansion caused by the alkaline aggregate reaction may prevent the additional improvement in compressive strength. It was concluded that in order to secure the long-term commonality and underwater stability of the geopolymers, it is desirable aging geopolymers while immersing it underwater for more than 21 days after curing using an autoclave.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.2
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• pp.68-76
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• 2022

This study was performed to investigate the mechanism of the change in compressive strength of autoclave cured geopolymers. Specimens were immerged in distilled water, 2M, 8M, and 14M alkaline solutions for 3, 7, and 21 days. The change in the specimens immersed in a short period of time was not significant, but the compressive strength of the specimens immersed in the distilled water and 8M alkali solution) for 21 days increased more than twice as much as before immersion because of additional geopolymerization. However, compressive strength decreased due to the alkaline aggregate reaction when alkaline solution was supplied more than a certain level of concentration. Therefore, immersing the specimens for more than 21 days in the distilled water or 8M alkaline solution would be desirable for the improvement of compressive strength of autoclave cured specimens.

• Journal of the Korea Concrete Institute
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• v.24 no.4
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• pp.481-490
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• 2012

Evaluation of chloride penetration is very important, because induced chloride ion causes corrosion in embedded steel. Diffusion coefficient obtained from rapid chloride penetration test is currently used, however this method cannot provide a correct prediction of chloride content since it shows only ion migration velocity in electrical field. Apparent diffusion coefficient of chloride ion based on simple Fick's Law can provide a total chloride penetration magnitude to engineers. This study proposes an analysis technique to predict chloride penetration using apparent diffusion coefficient of chloride ion from neural network (NN) algorithm and time-dependent diffusion phenomena. For this work, thirty mix proportions with the related diffusion coefficients are studied. The components of mix proportions such as w/b ratio, unit content of cement, slag, fly ash, silica fume, and fine/coarse aggregate are selected as neurons, then learning for apparent diffusion coefficient is trained. Considering time-dependent diffusion coefficient based on Fick's Law, the technique for chloride penetration analysis is proposed. The applicability of the technique is verified through test results from short, long term submerged test, and field investigations. The proposed technique can be improved through NN learning-training based on the acquisition of various mix proportions and the related diffusion coefficients of chloride ion.