• Journal of the Korean Geotechnical Society
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• v.29 no.11
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• pp.17-27
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• 2013

This study is to prove the efficiency of geo-synthetics on the crushed stone layer by experiments. The strength of PET mat as reinforcing soft ground was verified through the loading experiments. Also, PP mat was used to protect the blockage of crushed stone layer by the filled soil, whose efficiency was examined according to loading and infiltration conditions. The crushed stones were penetrated into clay layer if the PET mat was removed, which was verified by loading experiments. In addition, the cohesioness of soil without PP mat made the blockage of stone layer easily, which reduced the infiltration capacity by about 98%.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.113-117
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• 1993

The purpose of this study is to raise the strength of concrete with admixture. The natural zeolites and mud stone, abundant in this country, were used as admixture for high-strengthening of concrete. Proper workability was gained by using the superplasticizer. The optimum replacement ratio of zeolite mud stone was 10% on unit -cement amount. At these optimum replacement ratio, the strength development over the plain concrete was 34% for zeolite and 16% for mud stone. Through this study, we concluded the natural zeolite and mud stone were adequate admixture for the high-strengthening of concrete.

• Journal of Industrial Technology
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• v.24 no.B
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• pp.89-94
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• 2004

This Study is results of experimental works to investigate the characteristics of vibro-compaction of crushed stones having coarse grain sizes. For testing material, crushed stone, sieved within very narrow ranges of grain size distribution, was used. Cyclic loading apparatus was used to apply cyclic loading to the specimen prepared in the mold. Tests were performed by changing the ratio of the maximum to the minimum stress, frequency and the magnitude of the maximum and the minimum stresses. Settlement of specimen due to cyclic loading was measured to analyze the compaction efficiency and sieve analysis test after cyclic loading test was also carried out to find the crushing rate of the specimen. As results of cyclic loading test, normalized settlement in terms of specimen height tends to be converged around loading cycle number of 1500. The magnitude of normalized settlement is in the range of 3.11 ~ 8.57%. The crushing rate is in the range of 4.46 ~ 8.78%. Normalize settlement and the crushing rate tend to increase with decreasing the ratio of the maximum to the minimum stresses and they tend to increase with increasing the frequency and the magnitude of the maximum and the minimum stresses for the given ratio. In conclusions, compaction rate of crushed stone is controlled by the dynamic stress (difference between the maximum and the minimum stresses) and the crushing rate is dominated by applied energy to the specimen.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.11c
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• pp.129-141
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• 1999

This paper presents the results of plate load test and dynamic load test performed to evaluate the performance of geocell where it is used to reinforce soft subgrade for high-speed railroad. Efficacy of geocell was observed in increase in bearing capacity of subgrade and reduction of thickness of reinforced sub-ballast. Plate load tests were carried out at four different places with varying foundation soil strength as a function of number of geocell layer, type of filler material, thickness of cover soil, and the presence of non-woven geotextile. Dynamic load tests were performed in a laboratory. The test soil chamber consists of, from the bottom, 50 cm thick clayey soil, one layer of geocell filled with crushed stone, 10 cm thick crushed stone cover, reinforced sub-ballast of varying thickness, 35 cm thick ballast. This configuration was determined based on the results of numerical analysis and plate load tests. For each set of the dynamic load tests, loads were applied more than 80,000 times. One layer of geocell underlying a 10 cm thick cover soil led to an increase in bearing capacity three to four times compared to a crushed stone layer of the same thickness substituted for the geocell and cover soil layer. Given the test conditions, the thickness of reinforced sub-ballast can be reduced by approximately 35 cm with the presence of geocell.

• Journal of the Korean GEO-environmental Society
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• v.3 no.3
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• pp.65-77
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• 2002

Based from the results of various field and laboratory tests, it was determined that VCCP(Vibrated Crushed-stone Compaction Pile) Method is more effective compared to SCP(Sand Compaction Pile) Method. VCCP method effectively increases soil bearing capacity and reinforces soil and slopes, prevents liquefaction, enhances drainage. But when it comes to the engineering design these factors are not considered, instead designs are performed using practical methods and equations. Furthermore, this method is very economical since crushed stone can be used instead of sand and it can be also used in off-shore construction. In this paper, it will be synthetically considered technical state at the present time, research object after this and necessity of research for VCCP Method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.404-408
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• 2006

In this paper, connection strength between facing block and tie-bar was investigated through experimental study with varying in-fill material such as concrete, soil and crushed stone. Also, connection strength between anchor block and tie-bar was investigated with varying in-fill material. According to the experimental results, in case of using in-fill concrete, connection strength between facing block and tie-bar was larger than allowable tension load of tie-bar. Whereas in case of using in-fill soil or crushed stone, connection strength between facing block and tie-bar was less or similiar to allowable tension load of tie-bar. Connection strength between anchor block and tie-bar for which crushed stone was used as in-fill material, was larger than allowable tension load of tie-bar.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.507-514
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• 2005

In this construction case study, Crushed stone under 100mm diameter was carried out a test compacted construction for subgrade in the 3rd. runway of the 2th Incheon International Airport Construction area. Conforming to specification needs a minimum rolling compacted number 10 for upper subgrade 100% compaction degree indicated in Federal Aviation Administration and $K_{30}{\geq}20kgf/cm^3$ in plate bearing test. $K_{30}$ to be acquired 100% compaction degree of upper subgrade is confirmed to about $31kgf/cm^3$ from correlation $K_{30}$ vs relative compaction degree.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.5
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• pp.103-111
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• 2012

In this study, the full-scale laboratory model test on utilization of recycled aggregates and crushed stone as vertical drains to use an alternative material of sand in soft ground is performed. The settlement and pore water pressure were measured to evaluate the discharge capacity and filed application, and the results were compared and analyzed through the finite element method. The measured and estimated settlement in all vertical drain materials decreases gradually with the load increase. The measured settlement 6.55~8.63 mm, and the estimated by the Hyperbolic model was 7.45~7.92 mm. So the model used for the analysis can be applied to the settlement estimation of the actual field. The variations of pore water pressure with time showed constantly regardless of the load in all vertical drainage materials. The pore water pressure was similarity to that of sand after rapid drawdown. Therefore, it was applicable to the field because discharge capacity was enough to be an alternative material to the sand which had been being used as the vertical drains.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1415-1426
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• 2008

Stone columns, locally called "GCP (granular compaction pile)" can be used to improve strength and resistance against lateral movement of a foundation soil like rigid piles and piers. Also installation of such a discrete column facilitates drainage, and densifies and reinforces the soil in the sense of ground improvement. The integrity of the GCP has been indirectly controlled with the records of each batch including depth and the quantity of stone filled. An integrity testing was attempted using crosshole S-wave logging. The method is conceptionally same as the crosshole sonic logging (CSL) for drilled piers. The only and critical difference is that S-wave should be used in the logging, because P-wave velocity of the stone column is less than that of ground water. The crosshole sonic logger does not have the capability to measure S-wave propagating through the skeleton of crushed stone. An electro-mechanical source, which can generate either P- or SH-waves, and a 1-D geophone were used to measure SH-waves. Two 76mm diameter cased boreholes were installed 1 meter apart across the nominal 700mm diameter stone column. At every 10cm of depth, shear wave was measured across the stone column. One more borehole was also installed 1 meter outward from the one of the above boreholes to measure the shear wave profile of the surrounding soil. The diametric variation of the stone column with respect to depth was evaluated from the shear wave arrival times across the stone column, and shear wave velocities of crushed stone and surrounding soil. The volume calculated with these variational diameters is very close to the actual quantity of the stone filled.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.103-111
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• 2012

One of the basic physical properties of the hardened cement paste, the rigidity, is deteriorated during concrete matrix forming, depending on the replacement rate of the crushed stone powder, and due to drying shrinkage. Therefore, the concrete containing crushed stone powder has been limitedly used as non-structural construction material. To improve these disadvantages, a hydrothermal reaction employing method can be considered. High-temperature and high-pressure water is involved in the hydrothermal reaction in the mixing with specific materials. The rigidity improving mechanism is related to the synthesis of calcium silicate. The calcium silicate is produced through reaction between calcium compounds and the silicic acid. Various kinds of calcium silicate can be produced depending on the CaO/$SiO_2$ mole ratio, the temperature of the hydrothermal synthesis, the pressure, and the reaction time. The product of the synthesis mechanism, tobermorite crystal, plays a pivotal role for the rigidity reinforcement. The crushed stone powder, analyzed in this study, contains 50 to 60% of $SiO_2$ and 10 to 20% $Al_2O_3$. The composite rate is appropriate to create the tobermorite crystal through formation of hardened cement matrix under the hydrothermal synthetic conditions and with the CaO in the cement. Moreover, further reinforcement was promoted using the property of material under the identical density through promoting the formation of tobermorite crystal.