Effect of microorganism on engineering properties of cohesive soils

Yasodian, Sheela Evangeline,Dutta, Rakesh Kumar,Mathew, Lea,Anima, T.M.,Seena, S.B. Techno-Press 2012 Geomechanics & engineering Vol.4 No.2

This paper presents the study of the effect of microorganism Bacillus pasteurii on the properties such as Atterbergs' limit and unconfined compressive strength of cohesive soils. The results of this study reveal that the liquid limit and plasticity index for all clay soils decreased and the unconfined compressive strength increased. Decrease in plasticity index is very high for Kuttanad clay followed by bentonite and laterite. The unconfined compressive strength increased for all the soils. The increase was high for Kuttanad soil and low for laterite soil. After 24 h of treatment the improvement in the soil properties is comparatively less. Besides the specific bacteria selected Bacillus pasteurii, other microorganisms may also be taking part in calcite precipitation thereby causing soil cementation. But the naturally present microorganisms alone cannot work on the calcite precipitation.

Discussion of “Physio-Chemical Properties, Consolidation, and Stabilization of Tropical Peat Soil Using Traditional Soil Additives – A State of the Art Literature Review” by Afnan Ahmada, Muslich Hartadi Sutantoa, Mohammed Ali Mohammed Al-Bareda, Indr

Brendan C. O’Kelly 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.8

This discussion article provides commenting on the sections of the review paper by Ahmad et al. (the authors) concerning consistency limits determinations for peats and peaty soils, drawing on the writer’s experiences regarding the usefulness of liquid limit (LL) and plastic limit (PL) testing/results for these soils in explaining their geotechnical behaviors/properties. From the writer’s experience, despite being regularly specified in geotechnical engineering practice and used in research work, the conventional consistency limits tests generally do not produce physically meaningful results when testing peat soils, especially for more fibrous peats. Hence, the writer does not agree with the authors’ recommendations on consistency limits testing of peats; namely, they recommended that an utmost effort is needed to improve the quality and standard of the thread rolling test and the fall-cone test for consistency limits determinations of highly organic soils such as peat. Rather than grappling with various known inherent shortcomings of consistency limits testing for peats and other highly organic soils, a suggested way forward for assessing the likely geoengineering behavior/properties of these materials points to the routine measurement of a more useful suite of index tests; namely, their natural water content, organic content, fiber content, and humification (decomposition) level. In this discussion, the above aspects are explored in detail, including greater elaboration of the writer’s earlier research work in this area, which was touched on in the authors’ paper.

동해 울릉분지 심해토의 지반공학적 특성(2)

김영문(Youngmoon Kim),이종섭(Jongsub Lee),이주용(Jooyong Lee),이창호(Changho Lee) 한국지반환경공학회 2013 한국지반환경공학회논문집 Vol.14 No.5

천연자원을 개발하기 위한 심해저 탐사의 필요성이 증가하고 있다. 동해 울릉분지에서 수행된 가스 하이드레이트 심부 시추 사업(UBGH2)에서 획득된 시료로 지반공학적 기본특성 및 강도특성을 분석하였다. 아터버그 한계, 비표면적, 입도분포 등 기본 토질 실험을 실시하고 선행연구와 비교하였다. 광물학적 특성, 화학 조성, 미세구조 관찰을 위하여 XRD, SEM 그리고 EDS를 실시하였다. 또한 벤더 엘리먼트를 설치한 삼축압축셀을 이용하여 삼축압축실험을 수행하면서 강도정수와 전단파 거동을 분석하였다. The necessity of exploration in deep sea increases to develop the natural resources. The deep marine sediments, which were recovered from the hydrate occurrence regions during the Ulleung Basin Gas Hydrate Expedition 2 (UBGH2), East Sea, Korea in 2010, are explored to obtain the geotechnical characteristics and strength parameters. The index properties of the specimens including the atterberg limits, specific surface, and particle size distribution are measured and compared with the previous studies. X-ray diffraction, scanning electron microscope, and X-ray energy dispersive spectroscopy are conducted to analyze the clay mineralogy, chemical composition, and microstructure of the sediments. Strength parameters and shear wave velocities are measured with the axial strain by using an instrumented triaxial device. The strength parameters estimated by empirical equations are compared with the experimental results.

정확한 소성한계 측정을 위한 새로운 실험법 제안

고재민(Jae-Min Ko),이병석(Byung-Suk Lee) 한국산학기술학회 2018 한국산학기술학회논문지 Vol.19 No.6

지반조사에서 지반재료 특성의 판단은 매우 중요하다. Casagrande는 재료적 특성을 이용하여 흙을 분류하였다. 액 · 소성한계 시험은 흙의 기본적인 정보를 얻기 유용하며 실트와 점토를 분류하는 효과적인 방법과 재료 특성인 전단강도, 수축, 팽창 등의 정보를 제공한다. 액성한계와 다르게 소성한계는 시험절차의 모호성으로 많은 지반 공학자 및 기술자들이 시험결과에 의문을 제기하고 있다. 이를 해결하기 위해 낙하에너지를 이용한 새로운 소성한계 측정법을 제안하였다. 본 연구에서는 새로운 소성한계측정법의 정확성을 검토하기 위하여 새로운 카올리나이트, 일라이트, 벤토나이트를 각각 일정비율로 혼합하고 국내 서해안 일대의 시료를 채취하여 소성한계 측정법을 종래 방법과 비교 하였다. 비교 실험을 통한 검토결과 새로운 시험법의 시험값은 기존의 thread rolling시험의 시험값의 오차 범위가 10%에서 약 2%의 차이로 시험의 재현성이 높으며 기존 소성한계 시험값의 기울기와 차이가 0.11519 ~ 0.1925로 거의 시험의 결과 값이 유사 또는 일치하고 있음을 알 수 있었다. 또한 새로운 시험법을 보다 간편하게 적용할 수 있도록 일점법을 제안하였다. An examination of the characteristics of the ground material in is very important in a ground investigation. Casagrande classified soil using the material properties of soils. The liquid-plastic limit test is useful for obtaining basic information of soil, and is an effective method for classifying silt and clay, as well as the material properties, such as shear strength, shrinkage, and expansion. Unlike the liquid limit test, the plasticity limit test is due to the ambiguity of the test procedure. Many geotechnical engineers and scholars have questioned the test results. In this study, a new plasticity limit method was used to compare with the thread rolling method with kaolinite, ilite and bentonite at a certain ratio, and samples were collected from the west coast of Korea. As a result of the comparison, the test value of the new test method showed high reproducibility because the error range of the test value of the conventional thread rolling test was only 10% but the error range of the new test values decreased to 2%. The difference in the slope of the existing plasticity test values was 0.1519 ~ 0.1925, and the results of the test were similar or coincided with each other. Aone - point method was proposed to make it easier to apply the new test method.

열처리에 따른 점토의 애터버그 한계 영향

민덕기,황광모,이성호 한국지반공학회 2007 한국지반공학회논문집 Vol.23 No.2

본 연구에서는 카올린광물과 벤토나이트로 혼합물에 대한 열처리의 영향을 조사하였다. 100℃에서 500℃까지 100℃씩 온도를 증가시켜 인공적으로 생성한 혼합점토시료에 대하여, 열처리에 따른 건설재료의 강도특성을 분석코자 액성한계와 소성한계의 변화를 조사하였다. 실험 결과, 액성한계는 100℃에서 300℃ 사이에서는 약간 감소하는 경향을 나타내었으며, 300℃ 이후에는 액성한계가 급격히 감소하였다. 반면, 소성한계는 열처리의 영향이 크지 않았으며, 500℃로 처리한 혼합점토시료 모두에서 비소성(N.P.)을 나타내었다. 열처리에 따른 NaCl 함유량은 열처리 온도가 증가함에 따라 감소하는 것으로 나타났으며, 수소이온농도(pH) 역시 열처리의 크게 영향을 받는 것으로 나타났다. 양이온교환능력(C.E.C.) 또한, 열처리 온도에 따라 감소하는 경향을 보여 열처리에 따라 혼합점토의 액・소성한계가 영향을 크게 받는 것으로 나타났다.

Experimental Investigation on Compaction and Atterberg Limits Characteristics of Soils: Aspects of Clay Content using Artificial Mixtures

Zhang Kunyong,Charkley Nai Frederick 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.2

The influence of different proportions of clay minerals on the moisture density relationship and index properties of clay soils are not clearly understood because of the different factors that come into play in natural soil formation. This study used 11 different remolded samples prepared by combining double mixtures of commercially available powdered kaolinite, montmorillonite and quartz in proportions of 30%, 50%, 70% and 100% based on dry unit weight to investigate the relationship between different proportions of clay minerals with index properties and compaction characteristics of clay soils. The results described the influence of different proportions of clay minerals on the liquid limit, plastic limit and plasticity index measured using the fall cone penetration test. Also, the variation of maximum dry density and optimum moisture content with different clay mineral proportions has been analyzed. In addition, equations are presented with significant correlations to show the relationship between Atterberg limits, compaction parameters and the proportion of clay minerals. Knowledge on the effect of the different clay minerals on the moisture density relationship and index properties can be used to predict the behavior of compacted clay soils encountered in engineering practices and reduce the time and effort needed for assessing the suitability of clay soils and clay liners for engineering use.

A study of the plasticity of lightweight aggregate green bodies including bottom ash

Yootaek Kim,이기강,강승구,Yugwang Ryu,Hyejin Jeon,Junghwan Kim,장창섭,Sung-Gi Lee 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.2

The plasticity of clay-based green bodies including bottom ash(BA) from power plants were investigated. The plasticity indices of clay-base green bodies using Atterberg limits were measured. The usefulness of plasticity indices was confirmed by mapping the applicable forming region and through the actual extrusion process. Possible forming compositions were examined using various contents of water, bottom ash, stone dust, and sewage sludge. The relationship between the properties of aggregates and plasticity of green bodies was also investigated. Suitable compositions for forming aggregates by the extrusion method can be found by measuring the plasticity indices of green bodies and a map of the plasticity indices was matched with the results of actual extrusion process. The properties of aggregates were greatly influenced not only by the raw materials but also by the plasticity of green bodies.

Physio-Chemical Properties, Consolidation, and Stabilization of Tropical Peat Soil Using Traditional Soil Additives – A State of the Art Literature Review

Afnan Ahmad,Muslich Hartadi Sutanto,Mohammed Ali Mohammed Al-Bared,Indra Sati Hamonangan Harahap,Seyed Vahid Alavi Nezhad Khalil Abad,Mudassir Ali Khan 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.10

Peat is formed by the degradation of plants and animals in the lack of oxygen and is widely known for its very weak geotechnical characteristics. This is the reason to be considered as an unsuitable foundation soil for construction activities. Several attempts have been made to characterize and stabilize peat soil to make construction viable. This study encapsulates an extensive literature review of the available published data for Atterberg limits, consolidation, and stabilization of peat soil using traditional additives, especially cement and lime. Moreover, peat formation and distribution around the world are also discussed. The analysis of the gathered data shows that peat soils having a high amount of fibers may suffer a large amount of secondary consolidation when the load is applied. Besides, the compressibility factors vary for Malaysian peat due to different water and organic contents. The improvement of peat soil is challenging and expensive, requiring an extra amount of stabilizer for the initiation of the stabilization process. However, the optimum and threshold stabilizer’s dosage for peat is also a challenging task to predict due to several factors affecting the stabilization process. Lastly, the study concludes with recommendations on the implication of the fall cone and thread rolling tests for the determination of Atterberg limits of fibrous peat, effective consolidometer for peat, and utilization of traditional additives for peat soil stabilization.

Soil stabilization of clay with lignin, rice husk powder and ash

Canakci, Hanifi,Aziz, Aram,Celik, Fatih Techno-Press 2015 Geomechanics & engineering Vol.8 No.1

This article presents the result of laboratory study conducted on expansive soil specimens treated with lignin, rice husk powder (RHP) and rice husk ash (RHA). The amount of lignin produced from paper industry and RHP were varied from 0 to 20% and RHA from 0 to 10% by weight. The treated specimens were subjected to unconfined compressive strength (UCS),swelling test and Atterberg limit tests. The effect of additives on UCS and atterberg limit test results were reported. It was observed that the additives and curing duration had a significant effect on the strength value of treated specimens. Generally (except the sample treated with 20% RHP for 3-day) with increasing additive and curing duration the UCS value increases. A RHP content of 15% was found to be the optimum with regard to 3-day cure UCS.

동해, 울릉 분지 심해토의 지반공학특성

이창호,윤태섭,산타마리나,박장준,이종섭 한국지반공학회 2009 한국지반공학회논문집 Vol.25 No.6

There has been an increase in the investigation of deep sea sediments with a consequent increase in the amount of energy required to undertake these investigations. The geotechnical characteristics of Ulleung Basin sediment are explored by using depressurized specimens following methane production tests carried out on pressured core samples obtained at 2,100 m water depth and 110 m below sea floor. Geotechnical index tests, X-ray diffraction, and scanning electron microscope are conducted to identify the geotechnical index parameters, clay mineralogy, chemical composition, and microstructure of the sediments. Compressibility, and elastic and electromagnetic wave parameters are investigated for two samples by using a multi sensing instrumented oedometer cell. The strength chatracteristics are obtained by the direct shear tests. The dominant clay minerals are mostly kaolinite, illite, chlorite, and calcite. The SEM shows a well-developed flocculated structure of the microfossil. Void ratio, electrical resistivity, real permittivity, conductivity, and shear wave velocity show bi-linear behavior with the effective vertical stress: as the vertical effective stress increases. The friction angle obtained by the direct shear test is about 21°, which is similar to the value observed in the Ulleung Basin sediments. This study shows that the understanding of the behavior acting on the diatomaceous marine sediment is important because it often maintains the useful energy resources such as gas hydrate and so will be the new engineering field in the next generation.