• Journal of the Korean GEO-environmental Society
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• v.23 no.9
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• pp.17-23
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• 2022

Using cement as a road subbase is economical, easily modified and supplemented and has excellent road pavement quality control. In addition, cement adheres well to sandy soils without adhesion, and it plays a role of permanently preserving adhesion in viscous soils with adhesion, so it can be widely applied as stable treatment with the advantages of increased strength, reduced compressibility. and improved durability. However, while cement is excellent in terms of strength for a road subbase, the material properties mean that it is difficult to maintain and reinforce when cracks or fractures occur due to dry shrinkage, and the pH increases in the ground due to hexavalent chromium eluting from cement. which can cause environmental problems such as groundwater contamination. Therefore, this study evaluates the usability of alternatives in the road base layer such as environmentally cementitious stabilizer and on-site soil generated from the site. We intend to reduce the environmental damage and evaluate the durability. To evaluate the applicability of the site, Environmental stability test and freeze-thaw test and wetting-drying test was conducted to evaluate the strength characteristics of alternative materials on the road through the limited performance evaluation of environmentally cementitious stabilizer. The test ranges were set at mixing ratios of 10%, 20%, and 30% and ages of three days, and 28 days old to evaluate the early strength and reference strength according to the mixing ratio of the environmentally cementitious stabilizer.

• Journal of the Korean GEO-environmental Society
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• v.20 no.5
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• pp.39-46
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• 2019

Most of the soil used for reclamation is marine clay generated from dredging construction.The soft ground made of dredged clay has high water content and high compressibility, so the bearing capacity of the ground is very weak and it is difficult to enter the ground improvement equipment. Therefore, surface hardening treatment method is used to enter equipment prior to full-scale civil engineering work, and stabilizer is mainly used for cement series. Cement-based stabilizers have the advantage of improving the ground in a short period of time and have excellent economic efficiency, but they are disadvantageous in that they cause environmental problems due to leaching of heavy metals such as hexavalent chromium. In this study, environmental effects evaluation of dredged clay mixed with normal portland cement and environmentally friendly stabilizer was evaluated, and uniaxial compressive strength test and indoor model test were conducted to confirm the bearing capacity characteristics of the solidified layer.

• Cement Symposium
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• no.27
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• pp.21-24
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• 2000

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.267-267
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• 2008

시멘트를 이용한 지반개량 및 시멘트계 건설폐기물을 (예, 폐콘크리트, 및 시멘트 개량토 등) 성토재로 재활용하는 경우 지반 환경에 미칠 수 있는 영향으로는 (1) 시멘트에 함유된 6가 크롬($Cr^{6+}$) 및 (2) 강알칼리 물질의 용출이 있을 수 있다. 특히 $Cr^{6+}$의 경우 인체에 치명적인 발암성물질로 알려져 있어 이에 따른 주의가 필요하다. 최근 일본에서는 시멘트의 $Cr^{6+}$에 의한 지반오염이 우려됨에 따라 2000년 시멘트계 고화재를 지반에 사용하는 경우와 개량된 토양을 재이용하는 경우에는 토양환경기준을 만족하도록 규제하고 있다. $Cr^{6+}$외의 시멘트계 물질에 의한 환경오염으로는 강알칼리 물질의 유출이 있을 수 있다. 시멘트 개량토나 폐콘크리트 등의 건설폐기물을 성토재로 재활용하는 경우, 강우의 유입에 따라 구성물질인 수산화칼슘이 용해되어 높은 pH의 유출수가 발생한다. 강알칼리 유출수가 주변 하천 등으로 유입되는 경우 심각한 환경문제를 유발할 수 있으므로 이에 대한 기술적 검토가 필요하다. 본 발표에서는 시멘트계 물질에 의한 일본의 지반환경오염 사례 및 대책을 소개하였다.

• Magazine of RCR
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• v.15 no.3
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• pp.60-65
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• 2020

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.171-184
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• 2007

Chemical admixture stabilization has been extensively used in both shallow and deep stabilization in order to improve inherent properties of the soil such as strength and deformation behavior. An increment in strength, a reduction in compressibility, an improvement of the swelling or squeezing characteristics and increasing the durability of soil are the main aims of the admixtures for soil stabilization. Recently, the various advanced cement stabilizer mixing technique was developed. Advanced cement stabilizer mixing technique is environmentally-friendly and has an excellent mixing property and outstanding mixing speed. In this study, to develop the rural road pavement technology using cement stabilizer, compaction and unconfined compression test were performed with various mixing ratio and two types of soil(clay and silty soil). And the freezing/thaw test and bending strength test performed to develop suitable cement stabilizer material for stabilization of rural road. Based on the test results, the liquid types of cement stabilizer material and silty soil mixture are most suitable for rural road construction and although the mixing ratio is low, cement stabilizer mixture is effective for durability of rural road surface layer.

• Journal of the Korean GEO-environmental Society
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• v.12 no.9
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• pp.71-78
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• 2011

Cement treating technique, such as deep mixing method, has been used widely to stabilize the dredged clayey soil for many years. Despite of its effectiveness in treating soil by cement, several efforts have also been made to try to reduce the side effect of the cement that used to stabilize the dredged clay. However, authors considered that more detailed study on the physical and mechanical properties of lean-mixed soil-cement has been required to establish the design procedure to apply the practical problems. Therefore, in this study, the curing time and mixing ratio was used as key parameters to estimate the physical and mechanical properties including long-term behavior. The unconfined strength of lean-mixed soil-cement increase continuously during curing period, 270 days, while increasing rate becomes low in ordinary cement-treated dredged clay. We also concluded that cement-treated dredging clay shows apparent quasi overconsolidation behavior even in low cement proportion. By this study, fundamental approach was carried out for effective reuse of very soft dredged clayey soil both in mechanical and environmental aspect. It can be also expected that this study can propose a basic design data to use the lean-mixed soil cement.

• Proceedings of the Korean Geotechical Society Conference
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• 1998.10a
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• pp.381-388
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• 1998

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.3
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• pp.77-84
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• 2001

A few study has been performed on the durability of subbase treated with geo-cement for the farm road although many papers for the road treated with soil-cement were published. The objectives of the study are to develop the stabilizing method of subbase using additives of cement groups and 2nd additives such as gypsum and MgO, etc. A series of test was performed to investigate possible mixing ratios with geo-cement A, B, C, D and 2nd additives on the various soft soils from the rice paddy. Based on test results, durability index was greatly affected by geo-cement D which was mainly composed with gypsum. Compressive strength of clayey soil such as Soil I was less than threshold strength(30kgf/$\textrm{cm}^2$) but the strength was increased as addition of gypsum and MgO. It is recommended that geo-cement for soil stabilization has to be carefully chosen because strength characteristics of subbase are varied not only with soils but also with addition of geo-cement and 2nd additives. The developed method in this study can be used subbase treatment of low-cost agricultural roads.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.285-286
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• 2010

The purpose of this study aimed to evaluate properties of fluidity, compressive strength and bending strength of Loess mortar using non-cement binder to solve indentation due to reduction of compressive strength on exiting Loess bicycle load.