• 한국도로학회논문집
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• 제17권3호
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• pp.27-33
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• 2015

PURPOSES : To ensure appropriate RCC properties with sufficient strength development and workability, it is necessary to secure a proper level of consistency. It is also necessary to secure maximum dry density, which is an important factor for increasing the interaction of aggregate interlocking, leading to an augmentation of RCC strength. On the other hand, the dry density of RCC can be changed owing to the compaction conditions, water content, and particle size distribution. A Proctor test and a modified Proctor test were used for determining the optimum water content needed to achieve maximum dry density with different amounts of compaction energy. A Vebe test, on the other hand, was used for checking the level of consistency, which is important for producing a workable mixture. METHODS : To confirm the degree of compaction at various particle sizes, RCC mixtures with different sand/aggregate ratios were evaluated. The Proctor test and modified Proctor test were applied to these mixtures to check the effect of the aggregate gradation and compaction energy on the maximum dry density and optimum water content. During each test, three specimens were produced for all types of water content under each aggregate gradation. A compaction curve and the optimum water content and maximum dry density for each aggregate gradation were then obtained for both tests. The range of water content for the appropriate consistency of each aggregate gradation was determined through a Vebe test. The optimum water content was then evaluated based on this range. RESULTS : The compaction test results show that the modified Proctor test provides a higher maximum dry density and lower optimum water content compared with the standard Proctor test. For the modified Proctor test, two cases of aggregate gradation (s/a = 30% and 70%) had the optimum water contents outside of the appropriate water content range. For the standard Proctor test, on the other hand, none of aggregate gradations provided the optimum water content within the desired range. CONCLUSIONS : The modified Proctor test should be used for an RCC mixture design because it can provide adequacy between maximum dry density and consistency. Moreover, the compaction roller has become highly developed for higher compaction energy.

• 대한토목학회논문집
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• 제35권4호
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• pp.931-940
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• 2015

롤러전압콘크리트(Roller Compacted Concrete Pavement, RCCP) 공법은 적은 단위수량이 포함된 콘크리트 혼합물을 아스팔트 피니셔와 다짐 롤러를 이용하여 시공하는 공법이다. RCCP는 다짐 수준에 따라 강도 및 내구성에 많은 영향을 받게 된다. 또한 품질관리는 건조밀도를 기준으로 다짐도 관리를 시행하고 있다. 현장에서 최적의 건조단위중량을 모사하기 위해 수정다짐시험을 실시한다. 그러나 RCCP를 위한 수정다짐시험의 다짐곡선 분석에 명확한 기준이 제시되어 있지 않다. 본 연구에서는 함수비당 세 개의 샘플에 의한 수정다짐곡선의 기준을 설정하고 설정된 다짐곡선과 비교하여 더 적은실험횟수와의 신뢰성을 분석하기 위해 반복재현성을 고찰하였다. 이로 인해 세 번의 실험에 의한 수정다짐시험과 비교하여 두 번의 수정다짐시험은 0.5% 오차가 발생되며 신뢰도는 99.5% 이다.

• 한국농공학회지
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• 제23권3호
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• pp.65-77
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• 1981

The Compaction of fill dam is very important for increasing of the safty of dam. Vibration roller is used for the compaction of pervious materials such as sand and gravel. The principal objects of this study are to give a comstruction criteria of vibration roller and to find out the relationship between dry density and permeabity of pervious soil after compaction. The results in this study are summerized as follows. 1.The relationship between maximum dry density (Υdmax) and optimum moisture content(Wo) of modified compaction test is Υdmax=2. 74-0. 064w0 2.The maximum dry density decrease with increasing fine particle(n) and the relative formular is n==ae-brdmax 3.The maximum dry density is influenced more by passing rate of number 200 sieve than 4 sieve. 4.The coefficient of permeability are similar when the degrees of compaction are equal even though the spreading thickness of soil are different. 5.The coefficient of permeability(K)is greatly influence by fine particle passing number 200 sieve, and those relationship is inversely proportionate. 6.The K values of pervious soil are from 10-0 cm/sec to 10-4 cm/sec when degree of compaction by a modified method is from 90 to 95percent. 7.The coarser material is little influenced on the permeability with different density. 8.The increasing rate of permeability with decreasing degree of compaction is more influened by fine pacticle than number 200 sieve. When degree of compaction decrease from 100 percent to 90 percent the K values of SM and GM increase about 20 times but GW increase 6 times only. 9.The effect of compaction by vibration roller is greatly influenced by 6 passes and the increasing rate of the effect is decraased at 8 passes. 10. In order to get the degree of compaction of 95 percent or more, 6 to 8 passes of roller are generall required with 30 cm thickeness of soil for 4.5 ton to 6.5 ton vibration roller and 7 to 8 passes is required with 50cm thickness for 8 to 12 ton roller.

• 소성∙가공
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• 제21권4호
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• pp.228-233
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• 2012

In this study, powder compaction of AZO (alumina doped zinc oxide) powder was performed with a MTS 810 test system using a cylindrical die having a diameter of 10mm. Pressure-density curves were measured based on the load cell and displacement of the punch. The AZO powder compacts with various densities were formed to investigate the mechanical properties such as fracture stress of the AZO powder as a function of the compact density. Two types of compression tests were conducted in order to estimate the fracture stress using different loading paths: a diameteral compression test and a uniaxial compression test. The pressure-density curves of the AZO powder were obtained and the fracture stress of the compacted powders with various densities was estimated. The results show that the compact pressure dramatically increases as the density increases. Based on the experimental results, calibration of the modified Drucker-Prager/Cap model of the AZO powder for use in FE simulations was developed.

• 한국지반공학회논문집
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• 제34권12호
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• pp.105-113
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• 2018

본 연구에서는 고화제를 이용하여 개량된 노상재료의 배합에 따른 공학적 특성과 지지력을 분석하기 위하여 실내 및 현장시험을 실시하였다. 노상토 개량에 고화제로 사용된 재료의 주성분은 CaO와 $SO_3$이다. 고화제를 현장 토공재료인 저소성 점토(CL)와 혼합한 후 입도분포는 체 굵기가 커질수록 상대적으로 통과율이 낮아져 실트질 모래(SM)로 흙의 종류가 바뀌었을 뿐 아니라 소성지수와 수정 CBR 등의 공학적 특성이 노상토에 적합하게 개선되었다. 동일한 에너지로 다짐된 개량토의 다짐곡선으로부터 최대건조단위중량은 현장토 대비 약 6%가량 증가하고 최적함수비는 약간 감소하여 상당히 입도가 개선되었다. 실내 CBR 시험에서도 동일한 다짐에너지에서 적당량의 고화제를 투입한 개량토의 단위중량과 강도 증대효과가 현저히 크게 나타났다. 고화제 투입 후 조립분의 비율이 상대적으로 증가함으로 인하여 현장토 대비 초기다짐 시 팽창비가 3.3배 이상 감소되었고, 최종다짐 시에는 6.5배 이상 작게 나타났다. 시험시공이 이루어진 구간에서 일축압축강도는 설계강도 이상을 확보하면서 균질한 값을 유지하였다. 동일한 시공조건으로 현장에 적용한 후 확인시험 결과에서도 다짐 1일 후 시험한 6개소 모두의 지지력계수가 적절한 수준에서 목표값을 상회하고 그 변동성도 양호한 것으로 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.974-981
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• 2005

Because general laboratory tests for sand compaction pile method including unit-cell test device have fixed outside diameter, as area replacement ratio increase, diameter of sand pile increase. These condition can bring about overestimation of stiffness of composite ground. In addition, existing large soil box which consist of bellows type loading plate can occur serious mistake in checking the amount of drained water because there are additional drainage along the inside wall in device. Overcoming these shortcoming, this paper developed modified large scale soil box consist of piston type load plate. In this study, using this device, series of modified large scale soil box tests were performed, and investigated the settlement and stress transportation characteristics with area replacement ratio in sand compaction pile method.

• International Journal of Railway
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• 제1권2호
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• pp.64-71
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• 2008

The quality of track-bed fills of railways has been controlled by field measurements of density $({\gamma}_d)$ and the results of plate-load tests. The control measures are compatible with the design procedures whose design parameter is $k_{30}$ for both ordinary-speed railways and high-speed railways. However, one of fatal flaws of the design procedures that there are no simple laboratory measurement procedures for the design parameters ($k_{30}$ or, $E_{v2}$ and $E_{v2}/E_{v1}$) in design stage. A new quality control procedure, in parallel with the advent of the new design procedure, is being proposed. This procedure is based upon P-wave velocity involving consistently the evaluation of design parameters in design stage and the field measurements during construction. The Key concept of the procedure is that the target value for field compaction control is the P-wave velocity determined at OMC using modified compaction test, and direct-arrival method is used for the field measurements during construction. The procedure was verified at a test site and the p-wave velocity turned out to be an excellent control measure. The specifications for the control also include field compaction water content of OMC${\pm}$2% as well as the p-wave velocity.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1427-1439
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• 2008

The quality of track-bed fills of railways has been controlled by field measurements of density (${\gamma}_d$) and the results of plate-load tests. The control measures are compatible with the design procedures whose design parameter is $k_{30}$ for both ordinary-speed railways and high-speed railways. However, one of fatal flaws of the design procedures is that there are no simple laboratory measurement procedures for the design parameters ($k_{30}$ or, $E_{v2}$ and $E_{v2}/E_{v1}$) in design stage. A new quality control procedure, in parallel with the advent of the new design procedure, is being proposed. This procedure is based upon P-wave velocity involving consistently the evaluation of design parameters in design stage and the field measurements during construction. The key concept of the procedure is that the target value for field compaction control is the P-wave velocity determined at OMC using modified compaction test, and direct-arrival method is used for the field measurements during construction. The procedure was verified at a test site and the p-wave velocity turned out to be an excellent control measure. The specifications for the control also include field compaction water content of $OMC{\pm}2%$ as well as the p-wave velocity.

• 산업기술연구
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• 제22권B호
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• pp.211-218
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• 2002

The paper is to show the behavior of composit ground which is installed with sheet pile in soft soil improved by sand compaction pile. The results of load-settlement relationship, earth pressure, stress concentration characteristics, and final water content were obtained by centrifuge model test. Two cases of tests, installation of sheet pile on the corner and both side of the loading plate for the improved SCP ground which was designed twice of the footing width, were performed for the tests under the vertical and horizontal loading and both side of corner. Finite element program(CRISP) for sand compaction pile using elasto-plastic model and numerical analysis for soft soil using modified cam-clay constitutive equation were compared and analized with the results of model tests. The result of analysis show the increased bearing capacity of soil after, SCP and sheet pile was installed.

• 한국도로학회논문집
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• 제11권4호
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• pp.127-132
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• 2009

본 논문은 준고온 첨가제가 혼입된 3 종류(일반아스팔트, SBS 및 SMA)의 아스팔트 혼합물 다짐도 변화에 대한 시험 결과이다. 다짐 특성을 조사 분석하기 위하여 다짐 시간 변화와 준고온 첨가제 함량 변화에 의한 다짐도 측정을 실시하였으며, 다짐 온도를 일반시료에 비하여 $30^{\circ}C$ 및 $50^{\circ}C$를 낮추어 밀도를 비교하였다. 선회 다짐 장비를 사용하여 다짐 횟수 변화에 따른 다짐밀도의 변화를 측정하였다. 다짐시간 경과와 다짐도의 관계는 3 종류의 준고온 첨가제를 일반 아스팔트에 첨가하여 다짐시간 변화와 첨가제 함량 변화에 따른 다짐도를 측정하였다. 온도 저감에 따른 다짐도 비교는 일반 아스팔트 혼합물, 고분자 개질 아스팔트 및 SMA 혼합물 3 종류의 혼합물을 사용하여 시험을 실시하였다. 준고온 아스팔트 혼합물은 다짐온도 저감으로 인하여 일반시료 아스팔트 혼합물과 밀도의 차이가 발생하지 않아서 다짐도가 안정된 상태를 나타냈다. 한편, 혼합물의 종류 및 준고온 첨가제의 종류에 따라 밀도의 차이, 다짐도 변화의 추이 변화가 발견되어 이들 두 인자 사이에 상관관계가 있는 것으로 나타났다.