• International Journal of Highway Engineering
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• v.6 no.3 s.21
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• pp.55-64
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• 2004

Maximum dry unit weight, ${\gamma}_{dmax}$, is the most important engineering properties for subgrade soil. Existing models to predict ${\gamma}_{dmax}$ containing many parameters, seem to be rather complex. This paper presents new simple models to predict ${\gamma}_{dmax}$. for sandy soils, A number of sieve analysis and compaction tests for 36 types of sands were conducted to develop the regression-based models. Parameters used to estimate ${\gamma}_{dmax}$ are both the geometric mean and geometric standard deviation of the soils, or the particle-size distribution curve parameters. Maximum dry unit weights predicted by the models are in good agreement with the laboratory measurements for the soil samples obtained at 16 locations within the Korea.

• Journal of the Korean Geotechnical Society
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• v.29 no.1
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• pp.39-47
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• 2013

With the increase in the application of CLSM using coal ash, we performed a basic research on CLSM material, laying focus on the correlation between compressive strength and unit weight of lightweight foamed CLSM. The unconfined compression strength is a criterion for the judgment of the possibility of re-excavation and an important factor determining the economy, efficiency, and excavation character. However, to know the quantitative compression strength value takes a certain amount of time, because the applicability of unconfined compression strength of CLSM is judged by the standard of 28days. Therefore, in this study the relation between compressive strength and unit weight (foam slurry unit weight, apparent unit weight) is analyzed focusing on lightweight foamed CLSM. We also suggested a formula which can easily predict the 28-day compressive strength only using unit weight value without the need to cure the slurry for 28 days.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.1
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• pp.39-47
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• 2023

The demand for lightweight and high-strength materials is increasing. However, studies on the bond of concrete and reinforcing bars for high-strength lightweight concrete with a compressive strength of 120 MPa and a unit weight of 20 kN/m³ to structural members are lacking. Therefore, in this paper, 108 specimens of high-strength lightweight concrete with a compressive strength of 120 MPa and a unit weight of about 20 kN/m³ were fabricated, a direct pull-out test was performed, and the bond characteristics were evaluated by comparing the test results with design code. Compared to the decrease in unit weight, the solid bubble shows relatively little reduction in compressive strength and modulus of elasticity. It was f ound to have larger slip and parameter values than concrete with low compressive strength and unit weight.

• Journal of Wetlands Research
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• v.7 no.2
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• pp.145-158
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• 2005

To clarify the growth of Phragmites communis along the distance from the land, and investigate the effects by cutting the aboveground part, the height and dry weight of this species were surveyed from 2000 to 2001 on natural stands at tidal-flat of Hogog-ri, Jugog-myeon, Whaseong-city, Gyeonggi Province. At the stand near the rice paddy, mean density, mean height, dry weight per plant and dry weight per unit area of P. communis were $122.67plants/m^2$, 100.36 cm, 4.241 g, and $537.574/m^2$, respectively. The sizes of P. communis conspicuously increased from seaside to land side. At the stand isolated from the land, these properties were $102.30plants/m^2$ (in density), 43.894 cm (in height), 0.779 g/plant and $73.495g/m^2$, respectively, and the sizes of P. communis at the land side were relatively similar to those at sea side. The cutting of aboveground part resulted to the decrease of density and dry weight per unit area in next year, but did not influence on the height and weight per plant of P. communis.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2023.11a
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• pp.251-252
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• 2023

본 연구에서는 오염물의 선택적 흡수가 가능한 반응재료의 분광정보 예측을 위하여 반응재료 배합 조건에 따른 분광정보와 최대건조단위중량의 상관관계를 평가하였다. 그 결과, 배합 조건에 따라 최대건조단위중량 증가하게 되면, 최대분광반사율은 감소하였고, 이를 바탕으로 분광정보 경향의 예측이 가능하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.5C
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• pp.193-198
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• 2012

Field and laboratory tests were performed to investigate the swelling(L value) and shrinkage modulus (C value) of soil and rock mixtures using 2 sites. According to test results, when disturbed soil and rock were mixed with same amount (5:5), the maximum density was achieved and showed 19% and 18% increased at each site comparing with the unit weight of rock only. Since measured L values of mixtures were overestimated about 4 to 11% compare to estimated values based on the conventional method. While C values were underestimated about 13~20% compare to conventional values due to the development of compacting equipments and effective construction management. When rock and soil were mixed in the ratio of 5 to 5, the unit weight of the mixture was higher than that of other mixtures and rock or soil only.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.562-570
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• 2020

This study explores manufacturing technology and basic properties of high strength cement composites at 2,000kg/㎥ of specific weight. It is suggested that lightweight-high strength cement composites can be produced by substituting silica sand in ulta-high performance concrete mixture with lightweight materials such as solid bubbles and lightweight fine aggregates. The 28-day compressive strengths of cement composites with solid bubbles were from 116MPa to 141MPa at below 2.0g/㎤ of unit density while the cement composites with lightweight aggregates possessed lower compressive strength and higher unit density. The specific weight calculated from mixture proportions did not have significant difference with unit density of hardened cement composites, indicating that unit density of hardened cement composites can be estimated from the specific weight in mixture proportions.

• International Journal of Highway Engineering
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• v.8 no.2 s.28
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• pp.87-93
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• 2006

To evaluate the deformational characteristics of subgrade soils, four subgrade samples in Korea were tested using the RC and TS tests with various dry unit weight and water content. Both the maximum modulus and normalized modulus reduction curves of subgrade soils were affected by the dry unit weight. The normalized modulus was decreased about 20% with increasing of relative compaction of 5%. It was founded that the variations of modulus of subgrade soils in Korea were over 40% with water content variation of $\pm$2%, and those effects can be estimated by exponential model. However, the normalized modulus reduction curves were almost identical and independent of water content. It was also founded that confining pressure, loading frequency, dry unit weight, and water content have an affect on modulus of subgrade soils independently. Therefore, it can be considered that those effects are independent variables.

• Journal of the Korean GEO-environmental Society
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• v.16 no.2
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• pp.15-25
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• 2015

As the physical and mechanical properties of lightweight air-mixed soil change in the procedure of transportation of mix truck, it is necessary to assure whether the properties during construction satisfy those in design. In this study, variations of properties of mixed soil after transportation by mix truck are proved by field test. Lightweight air-mixed soil used field test the unit weight of $9.0{\pm}1.0kN/m^3$, the flow value of $190{\pm}20mm$ was produced. To analyze variations of properties of mixed soil the unit weight and flow value of the sample before and after transport was measured unconfined compressive strength tests were performed. Mixing time was 19~175 minutes diversified. As the test results, it is known that the density, the flow value and the unconfined compressive strength of lightweight air-mixed soil change by transportation, but these values satisfy the specifications of material of air-mixed soil. After transportation the average value of the unit weight and flow value change in the flow of the $(+)0.10kN/m^3$, 4.8 mm respectively, the average change in the unit weight and the flow value due to the mixing time was constant. And unconfined compressive strength of 28-day specimen increases from 20 to $150kN/m^2$. But, these values do not have some clear relationship with the transportation time within 175 minutes which is longest test time. Consequently, Within 175 minutes the changes of properties by transportation are too small to show some problems in the construction field.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.2
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• pp.529-536
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• 2014

Physical characteristics of cement-admixed clay such as water content, specific gravity, unit weight and void ratio are main factors for strength, compressibility and prediction of consolidation behavior. In the past, the physical characteristics of admixed soils could be understanded through complex laboratory tests and field survey after construction. In this study, the tests were performed with conditions such as clay water contents 0%-170%, cement contents 5%-25% and curing period 3-90days after that analyzed for changes which are water content, specific gravity unit weight and void ratio of admixed soils. A prediction of properties through mechanical relationships with clay in situ water content, cement content and curing period could be proposed using the test results. The prediction equation of void ratio of admixed soils was derived using void ratio equation in geotechnical engineering and compared with test results of bangkok clay and then this study could be verified.