• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.4
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• pp.931-940
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• 2015

Roller Compacted Concrete Pavement (RCCP), is a type of pavement using compaction roller and asphalt finisher on concrete mixture that contains low amount of water. RCCP strength and durability are greatly affected by compaction level. Quality control is performed by ensuring the degree of compaction at site based on dry density. In the field, Modified Proctor Test is used in order to obtain optimum dry density. However, there is no clear compaction curve analysis criteria of Modified Proctor Test for RCCP. In this study, compaction curve built by three samples of Modified Proctor Test was produced and it was used to compare with compaction curve contented lower number of samples (one and two samples) in order to analyze their reliability. Thus, a conclusion was drawn from the results; by comparing to the result from Modified Proctor Test of three samples, the use of two samples represented result with only 0.5% of error which means the reliability is 99.5%.

• The Journal of Engineering Geology
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• v.21 no.2
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• pp.133-145
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• 2011

Unsaturated soil column tests were performed for weathered gneiss soil and weathered granite soil to assess the relationship between infiltration velocity and rainfall condition for different rainfall durations and for multiple rainfall events separated by dry periods of various lengths (herein, 'rainfall break duration'). The volumetric water content was measured using TDR (Time Domain Reflectometry) sensors at regular time intervals. For the column tests, rainfall intensity was 20 mm/h and we varied the rainfall duration and rainfall break duration. The unit weight of weathered gneiss soil was designed 1.21 $g/cm^3$, which is lower than the in situ unit weight without overflow in the column. The in situ unit weight for weathered granite soil was designed 1.35 $g/cm^3$. The initial infiltration velocity of precipitation for the two weathered soils under total amount of rainfall as much as 200 mm conditions was $2.090{\times}10^{-3}$ to $2.854{\times}10^{-3}$ cm/s and $1.692{\times}10^{-3}$ to $2.012{\times}10^{-3}$ cm/s, respectively. These rates are higher than the repeated-infiltration velocities of precipitation under total amount of rainfall as much as 100 mm conditions ($1.309{\times}10^{-3}$ to $1.871{\times}10^{-3}$ cm/s and $1.175{\times}10^{-3}$ to $1.581{\times}10^{-3}$ cm/s, respectively), because the amount of precipitation under 200 mm conditions is more than that under 100 mm conditions. The repeated-infiltration velocities of weathered gneiss soil and weathered granite soil were $1.309{\times}10^{-3}$ to $2.854{\times}10^{-3}$ cm/s and $1.175{\times}10^{-3}$ to $2.012{\times}10^{-3}$ cm/s, respectively, being higher than the first-infiltration velocities ($1.307{\times}10^{-2}$ to $1.718{\times}10^{-2}$ cm/s and $1.789{\times}10^{-2}$ to $2.070{\times}10^{-2}$ cm/s, respectively). The results reflect the effect of reduced matric suction due to a reduction in the amount of air in the soil.

• Journal of the Korean GEO-environmental Society
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• v.16 no.1
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• pp.37-43
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• 2015

Korea has four distinct seasons, showing hot and humidity in summer and cold weather lasted in winter. Domestic research on earth work has been developed according to the seasonal characteristics, and most of research topics have focused on the effect of freezing-thawing on the performance of geo-materials. However, the previous research was performed on the ground compacted at room temperature and therefore, the effect of the sub-zero temperature at the time of construction was not fully investigated. The ground characteristics compacted at freezing temperature can be different from those at room temperature and show different characteristics of strength and deformation caused by freezing and thawing. Therefore, the compaction tests on sandy materials were conducted under various temperature at $-3^{\circ}C$ and $-8^{\circ}C$ with various fine contents of 0%, 5%, 10% and 15% in weight fraction. The effectiveness of soil compaction at below-freezing temperatures were compared with the compaction at room temperature at $18^{\circ}C$ in terms of the maximum dry unit weight and optimum water contents. Based on the test results, the maximum dry unit weight tends to decrease with the freezing temperature and the relative compaction at $-8^{\circ}C$ can not be satisfied with general specification standard.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.6
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• pp.1117-1123
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• 2016

Roller-Compacted Concrete Pavement (RCCP) is a type of pavement that shares conventional concrete pavement material characteristics and asphalt pavement construction characteristics. Even though RCCP is compacted in the same way and have similar aggregate gradation to asphalt pavements, its materials and structural performance properties are similar to those of conventional concrete pavement. With cement hydration and aggregate interlock, Roller-Compacted Concrete or RCC can provide strength properties equal to those of conventional concrete with low cement content. Therefore, compaction ratio of RCC can highly influence on its strength. In general, 95% of compaction ratio is required for proper strength development. RCC strength can be highly influenced by compaction energy which depends on compaction equipment and compaction method. Therefore, it is necessary to analyze the relationship between compressive strength and compaction ratio of RCC. RCCP specimens were produced at different compaction ratio by using different compaction methods and energies. The compaction ratio was defined by the ratio of the specimen's dry density and its maximum dry density. The maximum dry density was obtained from Modified Proctor test. 28 days compressive strength corresponding to each compaction ratio case was tested. Finally, the relationship between compressive strength and compaction ratio can be analyzed. For application of roller-compacted concrete in domestic construction site, the relationship is important for field compaction management.

• Journal of the Korean GEO-environmental Society
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• v.17 no.5
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• pp.37-46
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• 2016

In order to determine the variability of environmental characteristics of lightweight air-foamed soil using marine clay according to freezing-thawing and soaking conditions, unconfined compressive strength of the lightweight air-foamed soil samples made by changing the amount of cement under curing conditions of outdoor low temperature, underground or indoor wetting were observed. Compressive strength was not increased under freezing-thawing (temperature range of $-9.1^{\circ}C{\sim}17.2^{\circ}C$) regardless of the amount of cement but the more cement using, it was increased rapidly by underground curing conditions within 30 cm beneath ground level. Therefore, it is necessary to install insulation layer cutting off exterior cold air after construction of lightweight air-foamed soil in condition of freezing-thawing. Bulk density was increased too small under the long-time soaking condition, it tended to decrease rapidly when samples were dried up and had below 6% of water contents. But variability of compressive strength and bulk density was very small for preventing drying and keeping its wet state. The lightweight air-foamed soil that installed beneath ground water level or covered by soil can be evaluated as a long-term reliable construction material.

• Journal of the Korean Geotechnical Society
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• v.40 no.3
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• pp.93-100
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• 2024

Pore water freezes in low-temperature compaction, which leads to different compaction characteristics compared to room temperature conditions. In regions like Alberta, Canada, where organic soils are prevalent, compaction performance is influenced by the high water retention and compressibility of organic soils, as well as their sensitivity to freezing and thawing. Alberta's strict environmental regulations demand the reuse of excavated soil for backfill, and the long winter season creates challenging conditions for civil engineering projects. In this study, a laboratory compaction test was conducted to evaluate the low-temperature compaction characteristics of organic soils with varying organic content. The results indicate that the optimum moisture content increases as the organic content increases, and the maximum dry unit weight decreases by up to 21.9%. In addition, under temperature conditions below -4℃, no optimum moisture content was observed, and the dry unit weight decreased as the moisture content increased.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.119-119
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• 2017

부레옥잠은 대량 재배 및 수확이 가능한 수질정화용 식물로 생활하수, 축산폐수, 공장폐수 등의 수질정화 기능이 뛰어나고, 수확물은 건조 및 발효과정을 거쳐 가축 사료, 유기질 비료, 버섯 배지로 사용이 가능하고, 별도의 공업적 처리를 거치면 고부가가치의 바이오 연료, 연소용 연료로 사용이 가능한 친환경 농업 생산물로 본 연구에서는 부레옥잠의 고형연료 제조를 위한 수면에서 수확장치 개발을 위한 견인 특성을 파악하고 장치개발 가능성을 파악하고자 하였다. 부력구조물 부력, 부레옥잠 견인력, 부력을 측정하기 위한 실험 장치를 제작하여 부레옥잠 중량, 견인방식, 견인속도에 따른 견인력을 측정하였고, 경남 거제시에 위치한 저수지에서 실제 견인실험을 수행하였다. 실험결과 견인중량 및 견인 속도가 증가할수록 견인력은 증가하였으며 인력으로 부레옥잠을 견인하는 경우 부레옥잠 중량당 견인력은 약 $0.9{\sim}1.39kg_f$로 나타났으며 이는 향 후 부레옥잠 견인장치를 설계할 경우 부레옥잠 견인중량에 따른 견인력 산정 시 참고 자료로 매우 유용하게 활용 가능할 것으로 판단되었다. 저수지에서 견인실험 결과 견인속도 증가에 따른 유속저항으로 경운기에 의한 견인작업은 불가능하였으며 인력에 위한 견인 실험결과 부레옥잠 단위중량당 견인력은 견인바 3 m의 경우 1.5 ~ 2.6 N/kg, 견인바 6 m의 경우 2.1 ~ 5.4 N/kg로 비교적 크기로 나타났으나, 견인용 바에 따른 요인을 고려한 경우는 0.36 ~ 0.91 N/(kg-m)로 비교적 일정한 값을 보였다. 견인용 바 6 m, 무부하에서 인력과 경운기로 견인하는 경우 견인력은 39.24 N, 153.03 N으로 인력으로 견인하는 경우가 견인력이 작게 측정되었음. 이는 속도증가에 따라 물의 저항력이 증가함으로 나타난 결과로 부레옥잠 견인 시 견인속도는 0.36 m/s가 가장 적합한 것으로 판단되었다.

• International Journal of Highway Engineering
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• v.7 no.4 s.26
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• pp.31-39
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• 2005

Tests are conducted to analyze the compaction characteristics of domestic river sand used frequently for backfill in construction of electrical pipeline. As a result of test, the range of specific gravity of sand is found to be in between 2.63 and 2.67, and of maximum dry weight of sand is in between $1.70g/cm^3\;and\;1.86g/cm^3$. Also, the optimum moisture content is found to be in between 11.3% and 13.8%. The variability of compaction degree with respect to compaction energy is well captured by hyperbolic function.

• Geotechnical Engineering
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• v.10 no.2
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• pp.5-24
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• 1994

Resilient modulus tests were performed on five cohesive soils sampled from in -service subgrades and three cohesive soils compacted in the laboratory. It was concluded that in service resilient modulus can not be estimated from the resilient modulus of laboratory specimen compacted at same water content and dry density as in -service condition. The stress at 1 percent axial strain in unconfined compression tests ($Su_{1.0%}$) was found as a good indicator of the resilient modules ($M_R$), and the unique relationship between MR and $Su_{1.0%}$ was obtained. This relationship for the laboratory compacted soil is slightly different from that for the field compacted soil and the difference is less pronounced at the confining stress level expected to exist in subgrade. A proposed relationship itself is not affected by the changes in subgrade after construction and, therefore, it is applicable to as compacted and in service subgrade conditions.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1878-1882
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• 2010

이 연구는 제방의 침투 수리모형 실험의 자료를 이용해 안전도 평가 지표 선정을 위한 자료 제공하고 향후 수행할 침투 수치모의에 필요한 보정 및 검증 자료를 확보할 목적으로 수행하였다. 제방 축조 현장에서 구한 제체재료를 사용하여 실험실에 제방축소모형을 $14.5m{\times}0.6m{\times}1.6 m$의 수조 내부에 제작하였다. 제방 사면의 경사는 1:2, 제방 저면의 길이는 4.60 m, 제방 상부의 길이는 2.40 m, 제체의 높이는 0.55 m로 제작하였다. 모형제방은 제방축조 방법과 유사하게 다짐을 하기위해 흙을 쌓으면서 0.20 m 높이 마다 다짐을 실시하였다. 다짐방법은 고무망치를 이용한 층다짐을 하였다. 들밀도실험에 의한 제방모형의 건조단위중량과 다짐도는 각각 1.71g/cm3, 93%로 측정되었다. 홍수위 증가에 따른 비정상 상태의 침투수위 측정을 수행하였다. 수리모형실험은 약 8일 동안 수행하였다. 침윤선의 수두와 위압계별 수두는 상류쪽(제외지 사면)부터 증가하기 시작하며 하류쪽(제내지 사면)로 확장됨을 알 수 있으며, 실험 초기에는 상류쪽의 수두가 급격히 상승하지만, 점차 상승속도가 둔화되는 등의 일반적인 경향이 나타나고 있음을 확인할 수 있다. 실험시작 18시간 경과 후부터 제외지 사면 하단부에서 유출이 발생하였으며, 21시간 경과 후부터는 상류부의 수두가 안정되는 현상이 나타났다. 측정된 침투수위의 변화 양상은 향후 수치모형을 이용한 침투해석의 검보정 자료로 활용할 계획이다.