• Korean Journal of Soil Science and Fertilizer
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• v.41 no.6
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• pp.379-386
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• 2008

Calcined clay granules (pellet) have been used as a soil conditioner. The space among the pellets can secure drainage of water in soil and, simultaneously, can keep water for plants in the inner pore of that. However, the usage of the pellet has been restrained because fabrication of that requires a high energy and cost for heating over the temperate of $1000^{\circ}C$. Recently, SCS(Self-propagating Combustion and Sintering) method was developed and this method use the combustion energy of the preliminary mixed combustible. The SCS method is suitable to fabrication of small porous aggregate and requires a very low cost. This research applied the SCS method to coal refuses for fabrication of soil conditioner pellets. The coal refuses were pulverized under the size of $100{\mu}m$ and the pulverized powders were pelletized to the size of 4~6mm. The pellets were heated at the temperature of $1200^{\circ}C$ in the SCS furnace that was specially prepared for this research. Characteristics of the pellets were investigated and were compared with that of ordinary calcined clay pellet of kaolin; porosity, pore size distribution, bulk density, pH and etc.. Characteristics of the moisture retention in the pellets were measured by the centrifugal method: ASTM D425-88. The pellets of the coal refuses showed the higher values of the field capacity and the plant-available water than that of kaolin pellet. These results suggest the very low cost process that can utilize the coal refuses and can fabricate the lightweight porous soil conditioner of the very high plant-available water.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.5
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• pp.53-67
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• 2011

The major objective of this study was to quantify the effects of substrate depth and substrate composition on the development of sedum etc., in a sloped rooftop (6 : 12 pitch) environment during a 4-year period. The experiment was conducted from 2006 October to 2010 December under several conditions without soil erosion control : two substrate depth (5cm, 10cm), four substrate composition (A5N3C2, A3N3C4, A6C4, G5L3C2: A: artificial lightweight soil, N : natural soil, G : granite decomposed soil, C : leave composite, L : loess), four sloped roof direction ($E40^{\circ}W$, $W40^{\circ}N$, $S40^{\circ}W$, $N40^{\circ}E$). In this experiment 4 sedum etc., were used: Sedum sarmentosum, Sedum kamtschaticum, Sedum rupestre, Sedum telephium, flowering herbs (mixed seed : Taraxacum platycarpum, Lotus corniculatus, Aster yomena, Aster koraiensis), western grasses (mixed seed : Tall fescue, Creeping redfescue, Bermuda grass, Perennial ryegrass). The establishment factor had two levels : succulent shoot establishment (sedum), seeding (flowering herbs, western grasses). 1. Enkamat, as it bring about top soil exfoliation, was unsuitable material for soil erosion control. 2. Sedum species exhibited greater growth at a substrate depth of 10cm relative to 5cm. All flowering herbs and western grasses established only at a substrate depth of 5cm were died. A substrate depth of 5cm was not suited in sloped rooftop greening without maintenance. If additional soil erosion control will be supplemented, a substrate depth of 10cm in sloped rooftop greening without maintenance was considered suitable. 3. For all substrate depth and composition, the most abundant species was Sedum kamtschaticum. The percentage of surviving Sedum kamtschaticum was 73.4% at a substrate depth of 10cm in autumn 2007 one year after the roof vegetation had been established. But the percentage of surviving other sedum were 33.3%~51.9%, therefor mulching for soil erosion control was essential after rooftop establishment in extensive sloped roof greening was proved. To raise the ratio of plant survival, complete establishment of plant root at substrate was considered essential before rooftop establishment. 4. There was a significant interaction between biomass and substrate moisture content. There were also a significant difference of substrate moisture and erosion among substrate composition. The moisture content of A6C4 was highest, the resistance to erosion of A5N3C2 was highest among substrate composition. The biomass of plants were not significantly higher in A5N3C2 and A6C4 relative to A3N3C4 and G5L3C2, For substrate moisture and erosion resistance, A5N3C2 and A6C4 were considered suitable in sloped rooftop greening without maintenance. 5. There were significant difference among roof slope direction on the substrate moisture. Especially, the substrate moisture content of $S40^{\circ}W$ was lower relative to that of $N40^{\circ}E$, that guessed by solar radiation and erosion.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.411-418
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• 2001

The last 30 years have been significant worldwide growth in the use of EPS as a lightweight fill material. This paper analyzes the compressible inclusion function of EPS which can results in reduction of static earth pressure by accomodating the movement of retained soil. A series of model tests was conducted to evaluate the reduction of static earth pressure using EPS inclusion and determine the optimum stiffness of EPS, Also, field test was conducted to evaluate the reduction of static earth pressure using EPS inclusion. Based on field test it is found that the magnitude of static earth pressure was reduced about 20% compared with theoretical active earth pressure.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.217-218
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• 2023

This study is to develop porous concrete using super absorbent polymer, which possesses insolubility and high absorption capacity, as a substitute material for lightweight soil. Various mixtures were prepared using aggregates, cement, mixing water, and super absorbent polymer, and the absorption ratio and compressive strength were examined for each mixture. As the amount of super absorbent polymer added increased, the absorption ratio also increased, reaching up to 35-105%. However, the compressive strength decreased by 49.5% to 65.3%. This is believed to be due to the inherent properties of super absorbent polymer, which led to an increase in the absorption ratio but, in turn, reduced the binding strength of cement paste particles, resulting in a decrease in compressive strength.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.3
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• pp.146-151
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• 2013

In this study, the effect of addition of waste glassy slag produced from recycling of spent catalyst (denoted as waste glass hereafter) on the physical properties of artificial aggregates made of coal bottom ash and dredged soil (7 : 3 by weight base) was evaluated. Especially, the bloating behavior of artificial aggregates was analyzed by performing the relation study between the apparent density, water absorption and microstructure. The apparent density of artificial aggregates increased slightly with sintering temperature at $1050{\sim}1150^{\circ}C$, but decreased above $1150^{\circ}C$ showing bloating phenomenon. The bloating behavior of artificial aggregates was decreased so the apparent density increased with amount of waste glass added. Also, the water absorption of artificial aggregates decreased with sintering temperature. Above $1200^{\circ}C$, big fissure and much liquid were formed at the surface of artificial aggregates and these phenomena could be suppressed by increasing amount of waste glass added. The artificial aggregates fabricated in this study had an apparent density of 1.1~1.6 and water absorption of 8~22 % which meet KS requirements for the artificial lightweight aggregates.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.6
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• pp.318-323
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• 2009

The lightweight aggregates made of bottom ash (70 wt%) and dredged soil (30 wt%) were prepared to investigate the property differences at various sintering atmospheres. The green aggregates were sintered at $1150^{\circ}C$ and $1200^{\circ}C$ with oxidized, neutralized and reduced atmospheres. The aggregates sintered with oxidized atmosphere showed a clear border between shell and black core area. However, the aggregates sintered with a reduced atmosphere showed only black core area in the entire cross-section of the aggregates. The black core area of the aggregates sintered with a neutralized atmosphere increased with increasing $N_2$ gas flow rates. It was determined that the sintering atmosphere was similar to that of rotary kiln when the CO gas flow was 100 cc/min to make a reduced atmosphere in tube furnace. The water absorption rates of both aggregates from tube furnace with reduced atmosphere and rotary kiln were very similar to each other.

• Journal of the Korean GEO-environmental Society
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• v.15 no.12
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• pp.35-42
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• 2014

The efforts to reduce carbon emission have been made in many aspects and in road, the study to develop the construction method which will replace asphalt and cement is also underway. But given the low cost and high performance offered by cement, among many solidification agents, it's difficult to seek the competent alternative. Polymeric material has been used in various ways for its advantages including lightweight and easy process for complex function and generates less carbon emission, and thus it would possibly be efficient if it replaces soil pavement using cement. This study, using three different types of organic polymeric solidification agents with different solidification principle, is intended to identify the difference in strength depending on curing method, natural dry or oven dry. Applicability of organic polymeric solidification agents to walkway and bike lane was investigated and as a result of unconfined strength test, all of them satisfied the minimum strength requirements of bike lane. Furthermore, strength characteristics of soil pavement depending on variation of water content was evaluated to identify the relationship, thereby appropriate curing method using organic polymeric solidification agent is proposed.

• Journal of Ocean Engineering and Technology
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• v.28 no.2
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• pp.140-146
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• 2014

This study investigated the engineering characteristics of non-sintering binder-stabilized mixtures consisting of different ratios of a hardening agent(3%, 6%, 9%, 12%) for recycling industrial by-products through several series of laboratory tests. The hardening agents consisted of two kinds of non-sintering binders(NSB-1, NSB-2), which were developed by using inter-chemical reactions among blast furnace slag, phospho-gypsum, and an alkali activator. In addition, ordinary Portland cement(OPC) was used to compare the engineering characteristics of the stabilized mixture. An unconfined compressive test showed that the unconfined compressive strength increased with the curing time and mixing ratio. Experimental test results indicated that the 7-day strength of the NSB-1 mixture was similar to that of the OPC mixture. However, its 28-day strength was higher than that of the OPC mixture. The secant module of elasticity showed a range of $E_{50}=(42-109)q_u$ regardless of the agents. Based on the results of triaxial tests, the cohesion and friction angle increased with the mixing ratio.

• KIEAE Journal
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• v.11 no.1
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• pp.3-8
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• 2011

Sound absorbing materials used for lightweight panels and interior material are mainly made of fibroid material such as glass wool or rock wool. However these fiber type sound absorbing materials have some problems such that sound absorption could be decreased as time goes by because of durability. In addition, dust scattering from fiber type material can cause another problem in health. In this point of view, this study aims to develop environment friendly sound absorbing material using Hwangto(so called loess or yellow soil), a traditional housing material. Hwangto is natural housing material in Korea and generally known for improving indoor air quality. Hwangto panel is made to construct on the floor, wall and ceiling, and expected that there is not enough absorption. Present study tried to develop environment friendly sound absorbing material that has high sound absorption performance with good environment performance in terms of air quality. Pore rate was designed to maximize the absorption in the specific frequency bands, and two kinds of backing space were applied in order to see the effect of backing space. As a result peak frequency that has maximum absorption is going high as the pore rate is increased. The backing space provides more absorption and makes the peak frequency down to low.

• Structural Engineering and Mechanics
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• v.48 no.2
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• pp.257-274
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• 2013

In this study, seismic performance of one story hinged precast buildings, which represents the majority of existing lightweight industrial building stock of Turkey, was assessed. A lot of precast buildings, constructed in one of the important seismic zones of western Turkey, were investigated and building inventories were prepared. By this method, structural properties of inventory buildings and damaged precast buildings in recent earthquakes were compared. Damage estimations based on nonlinear analysis methods have shown that estimated damage levels of inventory buildings and observed damage levels in recent earthquakes are similar. Accuracy of damage estimation study and the simplicity of the one story precast building models implied that rapid seismic performance assessment method for these buildings can be developed. In this assessment method, capacity curves and vibration periods of precast buildings were calculated by using structural properties of precast buildings. The proposed assessment method was applied to inventory buildings by using two different seismic demand scenarios which reflect moderate and soft soil conditions. Comparison of detailed analysis and rapid assessment methods have indicated that reliable seismic performance estimations can be performed by using proposed method. It is also observed that distribution of damage estimations is compatible in both scenarios.