• Title/Summary/Keyword: Total void ratio

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A Study on the Sound Absorption Properties of Foamed Concrete According to Dilution Ratio of Foaming Agent (기포제 희석비율에 따른 기포콘크리트의 흡음특성에 관한 연구)

  • Kang Ki-Woong;Kang Chul;Kim Ha-Seok;Kwag Eun-Gu;Kwon Ki-Joo;Kim Jin-Man
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2005.05a
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    • pp.5-8
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    • 2005
  • Sound absorbing performance is affected by porosity and continuity of void, therefore it is important to maintain stabilization of foam and to analyze properties of void pore in hardened state. The purpose of this study is to analyze the sound absorption properties and void characteristic of foamed concrete according to dilution ratio of foaming agent. The results of this experiment were as follows. It is determined that an increase in total and continuous void ratio is achieved by increasing of dilution ratio, and a shorter absorbing time was exhibited at a higher continuous void ratio. When the average void size of foamed concrete was below 1.5mm, the tendency of sound absorption coefficient compared with general sound absorber was appeared similarly.

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Estimation of Void Ratio by Elastic Wave Velocities (탄성파 속도를 이용한 간극비 산정 기법 연구)

  • Yoon, Hyung-Koo;Jung, Soon-Hyuck;Jeong, Hun-Jun;Lee, Jong-Sub
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.03a
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    • pp.198-207
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    • 2010
  • Many methods and techniques have been developed to obtain the accurate design parameters in soft soils. In particular, several researchers suggest the techniques to get the void ratio for understanding the soil behavior. The objective of this paper verifies the accuracy of the proposed analytical solution for determining the void ratio based on the elastic wave velocities. The paper covers the theories of Wood, Biot, Gassmann and Foti proposed chronological order. The total theory represents the wave propagation in fully saturated medium. To verify the proposed analytical solution, the laboratory and field tests are carried out. After measuring the elastic wave, the void ratios are assessed using proposed equation. The volume based void ratios are also obtained for comparing with the estimated value by several equations. The values estimated by volume, Gassmann and Biot are show good similarity. However, the void ratios based on Wood and Foti methods have a slightly different trend. This study suggests that the theories of Biot and Gassmann may be a useful equation for assessing the void ratio using elastic wave velocities in the field.

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Correlation Analysis between Unit Weight and Thermal Conductivity in Porous Concrete Containing Natural Fine and Bottom Ash Aggregates (바텀애시와 천연 잔골재를 혼입한 다공성 콘크리트의 단위질량과 열전도도의 상관분석)

  • Seung-Tae Jeong;In-Hwan Yang
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.11 no.4
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    • pp.542-551
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    • 2023
  • In this paper, the thermal properties of porous concrete containing natural fine aggregates in bottom ash aggregates were analyzed. In this study, natural fine aggregates were used for bottom ash aggregates to understand the material properties of each aggregate and then used as an aggregate for porous concrete. A porous concrete specimen was manufactured by fixing the water-binder ratio at 0.25 and designating the compaction at 0.5, 1.5, and 2.5 MPa. Unit weight, total void ratio and thermal conductivity test were measured and discussed. As the compaction increased and the mixing ratio of natural fine aggregates increased, the unit weight and thermal conductivity increased, and the total void ratio decreased. In addition, the correlations between unit weight, total void ratio and thermal conductivity of porous concrete with previous experimental data were presented and the correlation coefficient (R2) was also analyzed.

Engineering Properties of Sound Absorbing Foamed Concrete Using Bottom Ash Depending on Mix Factors (배합요인에 따른 바텀애시 미분말을 사용한 흡음형 기포콘크리트의 공학적 특성)

  • Kim, Jin-Man;Kang, Cheol
    • Journal of the Korea Institute of Building Construction
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    • v.9 no.5
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    • pp.63-70
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    • 2009
  • This study is part of an ongoing research project on the development of a sound-absorbing lightweight foamed concrete manufactured by a hydro-thermal reaction between silica and calcium. As the silica source, pulverized bottom ash was used, and as several cementitious powders of ordinary portland cement, alumina cement and calcium hydroxide were used. Manufacture of foamed concrete was accomplished using the pre-foaming method to make a continuous pore system, which is the method of making the foam by using a foaming agent, then making the slurry by mixing the foam, water, and powders. The experiment factors are W/B, foam agent dilution ratio, and foam ratio, and test items are compressive strength, dry density, void ratio, and absorption rate, as evaluated by NRC. The experiment results showed that the sound absorption of lightweight foamed concrete satisfied NRC requirements for the absorbing materials in most of the experiments. It is thus concluded that foam ratio was the most dominant factor, and significantly affected all properties of lightweight foamed concrete in this study. W/B rarely affected total void ratio and continuous void ratio as well as compressive strength, and dry density and foam agent dilution ratio also had little effect onalmost all properties. The analysis of the correlation between NRC, absorption time, continuous void ratio, and absorption time showed that the interrelationship of the continuous void ratio was high.

Settlement Estimation of CFRD Considering Valley Shape During Construction Period (계곡형상을 고려한 CFRD의 축조 중 침하량 예측)

  • Park, Han-Gyu;Kim, Yong-Seong;Lim, Heui-Dae
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.10a
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    • pp.302-305
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    • 2005
  • In this study, settlement characteristics of 38 CFRD was investigated from monitoring data and the method to estimate the dam settlements considering valley shape during constructions was proposed. The construction modulus of dam was found to be dependent on void ratios and valley shape factor. The construction modulus varied with valley shape and decreased with increasing void ratio. Also, the modulus was increased when the shape coefficient was less than 4. The settlement investigation results showed that the total settlement was proportional to the value of the settlement coefficient multiplied by the shape coefficient divided by void ratio.

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Evaluation of Permeability Characteristics of Kimhae Clay by Laboratory Tests. (실내실험을 통한 김해점토의 투수특성 평가)

  • 김동휘;임형덕;김진원;이우진
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.03b
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    • pp.647-654
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    • 2000
  • During consolidation, the permeability of clay decreases with void ratio because of the reduction in total void space. After Kozeny(1927) and Carman(1956), many researchers have proposed the relations between void ratio and permeability. Most of the relations are expressed in the following forms as : (1) log e - log k(1+e), (2) e - log k, or (3) log e - log k. These relations have been found valid for a large number of normally consolidated clays. From laboratory test(CRS and I $L_{CON}$) results, the relation between void ratio and permeability of Kimhae clay was well defined in all of the three forms. Permeability change index, $C_{k}$, of Kimhae clay was in the range of 0.64~1,03 and average value of $C_{k}$ was 0.821. And the test results satisfied the experimental correlation between $C_{k}$ and e, $C_{k}$=0.5e. In log e - log k(1+e) relation, constant C was in the range of 1.91~4.74$\times$10$^{-8}$ cm/sec and n was in the range of 3.74~4.60.c and n was in the range of 3.74~4.60.74~4.60.0.

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Design and Performance Evaluation of Visualization System for Measuring the Void Fraction of Two-phase Flow (다상 유동 Void Fraction 가시화 장치 설계 및 성능 평가)

  • Choi, Chang-Hyun;Choi, Seong-Won;Song, Simon
    • Journal of the Korean Society of Visualization
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    • v.15 no.1
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    • pp.11-18
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    • 2017
  • A two-phase flow observed in a heat exchanger or nuclear power generation often has a profound effect on undesirable noise or flow characteristics. Void fraction, which refers to the ratio of gas (or liquid) to the total fluid, affects heat transfer coefficient, vibration and so forth. In other words, void fraction is one of most important parameters in two-phase flow since it contributes to comprehend the characteristics of two-phase flow. We developed a two-phase flow visualization system to measure cross-sectional and volumetric void fractions by using quick closing valves and image processing software. With this system, we could observe the plug, slug, and stratified flow patterns of two-phase flow and measure a myriad of void fractions. As a consequence of the experiment, we found that the estimated void fractions were largely coincident with the predictive values by Chisholm model.

Effects of the Compaction and Size of Bottom Ash Aggregate on Thermal Conductivity of Porous Concrete (가압다짐과 바텀애시 골재 크기 특성이 다공성 콘크리트의 열전도도에 미치는 영향)

  • Yang, In-Hwan;Jeong, Seung-Tae;Park, Ji-Hun
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.10 no.3
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    • pp.195-203
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    • 2022
  • In this paper, the effects of the bottom ash aggregate sizes and compaction levels on the thermal conductivity of porous concrete were investigated. In this experimental study, bottom ash was used as aggregates after identifying the aggregate characteristics. SA mixtures included hybrid aggregates, and DA contained only one particle size. The water-binder ratio was fixed at 0.30, and the compaction levels were applied to the concrete specimens at 0.5, 1.5, and 3.0 MPa. Unit weight, total void ratio, and thermal conductivity were measured and analyzed. As the compaction level increased, the unit weight and thermal conductivity increased in the SA mixtures, but the total void ratio decreased. In addition, the thermal conductivity of the specimens under oven-dried condition were lower than that of the specimens under air-dried condition. The correlation between the unit weight, total porosity, and thermal conductivity of porous concrete was analyzed. The thermal conductivity-unit weight correlation was proportional, while the thermal conductivity-total void ratio correlation was inversely proportional.

An Experimental Study on Thermal Property of Porous Concrete Containing Bottom Ash (바텀애시를 활용하는 다공성 콘크리트의 열전도 특성에 관한 실험 연구)

  • Jeong, Seung-Tae;Kim, Bum-Soo;Park, Ji-Hun;Yang, In-Hwan
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.9 no.4
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    • pp.625-632
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    • 2021
  • In this paper, the applicability of bottom ash to insulation concrete was investigated to increase the utilization of bottom ash. Bottom ash was used as the aggregates in porous concrete and extensive experiments were conducted to investigate the characteristics of porous concrete using two types of bottom ash aggregates. The water-binder ratios of 0.25 and 0.35 were chosen and concrete specimens was produced with the compaction of 0.5, 1.5, and 3.0MPa to analyze the material properties at different compaction conditions. After concrete specimens were cured for 28 days at water tanks, unit weight, total void ratio, and thermal conductivity were measured. Based on the measured experimental results, the relationships between the unit weight, total void ratio, and thermal conductivity of porous concrete containing bottom ash was presented.

Nonlinear regression methods and genetic algorithms for estimation of compression index of clays using toughness limit

  • Satoru Shimobe;Eyyub Karakan;Alper Sezer
    • Geomechanics and Engineering
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    • v.37 no.4
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    • pp.371-382
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    • 2024
  • Measurement or prediction of compression index (Cc) of soils is essential for assessment of total and differential settlement of structures. It is a well-known fact that this parameter is controlled by several index identifiers of soil including initial void ratio, Atterberg limits, overconsolidation ratio, specific gravity, etc. Many studies in the past proposed relationships for prediction of Cc based on different index properties. Therefore, this study aims to present a comparison of previously proposed equations for estimation of Cc. Data from literature was compiled, and a total of 90 and 623 test results on remolded and undisturbed specimens were used to question the validity of previously proposed equations. Nevertheless, the modeling ability of 7 and 12 equations for estimation of Cc of remolded and undisturbed soils were questioned by use of compiled data. Moreover, new empirical relationships based on initial void ratio and toughness limit for prediction of Cc was proposed by use of nonlinear multivariable regression and evolutionary based regression analyses. The results are promising-the performances of models established are quite acceptable, which are verified by statistical analyses.