• Magazine of the Korean Society of Agricultural Engineers
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• v.20 no.1
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• pp.4599-4613
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• 1978

This study was intended to investigate the effects of bituminous material content of soil-cement mixtures on their durability. For the purpose, unconfined compressive strength test, Freeze-thaw test, and wet-dry test were performed with three types of soil. Each type of soil was mixed with three levels of cement content and each soil-cement mixture was mixed with four levels of bituminous material content. For the unconfined compressive strength test, Freeze-thaw test and wet-dry test, 324, 108, and 108-specimens were prepared respectively. Unconfined compressive strength was measured at age of 7-days, 14-days and 28-days using 108-specimens in each age. The soil-cement loss rate due to freeze-thaw and wet-dry were calculated after 12 cycles of test using 108-specimens in each test. The results are summarized as follows : 1. Optimum moisture content was increased with increase of cement content, but maximum dry density was changed irregulary with increase of the cement content. 2. The unconfined compressive strength was increased with increase of cement content, bituminous material content and curing age. Cement is more effective factor than bituminous material on unconfined compressive strength of soil-cement Mixture. 3. It is estimated as the most economical cement content that the recommended cement content of A.S.T.M. because increasing rate of unconfined compressive strength at age of 28-days was low when cement content is above the recommanded cement content of A.S.T.M. among all types of soil. 4. Although a portion of cement content is substituted for bituminous material, the necessary unconfined compressive strength can be obtained. 5. The soil-cement loss was more influenced by wet-dry than Freeze-thaw 6. The bituminous material is more effective on the decrease of soil-cement loss than increase of unconfined compressive strength 7. The void ratio of soil-cement mixture was changet irregularly with increase of cement content, but that was decreased in proportion to the increase of bituminous material content. 8. The regression equation between the unconfined compressive strength and soil-cement loss rate were obtained as table 7.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.4 s.19
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• pp.29-36
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• 2005

In this study, relations among unconfined compressive strength, strain at maximum strength and depth were compared with each other. Test specimen is marine clay originated from the place near Ga-duck island in Busan city. In addition, influence of impure material contained in specimen and that of total core recovery(TCR) on unconfined compressive strength and degree of disturbance were investigated. As a result of tests, unconfined compressive strength decreases as strain corresponding to maximum strength increases. Also, the deeper the sampling depth and the bigger the TCR, the unconfined compressive strength increases. Especially, as the TCR increases, the unconfined compressive strength Increases and quality of specimen is enhanced.

• Magazine of the Korean Society of Agricultural Engineers
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• v.27 no.2
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• pp.57-71
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• 1985

The characteristics of compaction and unconfined compressive strength were investigated by mixing with lime to all soils adjusted by given percentages of two kinds of clays to sand to obtain the most effective distribution of grain size and the optimum lime content for soil stabilization. In addition, unconfined compressive strength and durability tested by adding of sodium metasilicate, sodium sulfate, sodium carbonate, sodium gydroxide and magnesium oxide to lime-soil mixture mixed with 8 percent lime to adjusted soil having the mixing percentage of 60 percent of cohesive black clay and 40 percent of sand by weight to get the effect and the optimum content of chemicals. The results obtained were as follows; 1.With the addition of more lime, the optimum moisture content was increased, and the maximum dry density was decreased, whereas the more the amount of clay and the less was the maximum drt density. 2. In the soil having more fine grain size the unconfined compressive strength was larger in the earlier stage of curing period, in accordance with the longer period, the mixing percentages of sand to clay showing the maximum unconfined compressive strength, on the basis of 28-day strength, were 60% : 40% (black clay) and 40% : 60% (brown clay) respectively. 3. The reason why the soil adjusted with black clay was remarkably bigger in the unconfined compressive strength than ones adjusted with brown clay for all specimen of lime-soil mixture was the difference in the kind of clay, the amount of chemical compositions the value of pH. Black clay was mainly composed of halloysite that reacted with lime satisfactorily, whereas the main composition of brown clay was kaolinite that was less effect in the enhance of unconfined compressive strength. Also the difference of unconfined compressive strength was because black clay was larger in the amount of composition of calcium oxide and magnesium oxide in the value of pH affecting directly on the unconfined compressive strength of lime-soil mixture than brown clay. 4. In the lime-soil mixture mixed with 8 percent of lime to soil that mixing percentage of sand to black clay was 60% : 40%, on the standard of 7-day strength, the effect of chemical was arranged in the order of magnesium oxide, sodium carbonate, sodium sulfate, sodium hydroxide and sodium metasilicate. 5. The optimum amount of chemical being applicable to the maximum unconfined compressive strength of lime-chemical-soil mixture was 1 percent by weight for air dry soil in the case of adding sodium carbonated and 0.75 percent on sodium hydroxide, the unconfined compressive strength was increased continuously with increase of the amount of chemical up to 2 percent of chemical content is the lime-chemical-soil mixture added sodium metasilicate, sodium sulfate and magnesium oxide. 6. It was considered that the chemical played and accelerant role of early revelation of strength because the rate of increase of unconfined compressive strength of all of lime-chemical-soil mixtures was largest on the 7-day cured specimen. 7. The effect of test on freezing and thawing after adding suitable amount of chemical on the lime-soil mixture mixed with 8 percent of lime to soil that mixing percentage of sand to black clay was 60% : 40% was arranged in the order of magnesium oxide, sodium carbonate, sodium sulfate, sodium metasilicate and sodium hydroxide.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.14-21
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• 2008

In this study, a series of CID tests were performed on gypsum-cemented specimens to determin the cohesion intercept and the confined stress start to break the cementation bonds (${q_i}'_{(BP)}$). And the relationships between the unconfined compressive strength ($q_{ucs}$) and cohesion intercept or ${q_i}'_{(BP)}$ were investigated. From the experiments, it was concluded that the friction angle of cemented sands is not affected by cementation while the cohesion intercept of cemented sands significantly influenced by cementation and is constant before ${q_i}'_{(BP)}$. By an analytical interpretation, the failure strength of cemented specimen could be represented by summation of the failure strength of uncemented specimen and the unconfined compressive strength of cemented one. And the cohesion intercept of cemented specimen was represented as a linear relation with the unconfined compressive strength. Those analytical values of failure strength and cohesion intercept almost coincided with the experimental values of those. In addition, the ${q_i}'_{(BP)}$ also could be related with unconfined compressive strength linearly.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.461-466
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• 1998

The purpose of this study was to evaluate the properties of unconfined compressive strength(UCS) of dry soil which was reinforced with short polypropylene fiber(SPPF). And the results were summarized as follows: 1. As water content was increased, unconfined compressive strength and strain of dry soil with no fiber added were decreased 2. As mixing ratio of fiber was increased, unconfined compressive strength and strain at failure of dry soil reinforced with SPPF were increased. 3. When mixing ratio was larger than 0.5％, unconfined compressive strength was gradually increased. 4. The longer fiber was, the larger post peak strength was obtained and the larger strain was reached.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.6
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• pp.71-77
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• 2016

This study was to evaluate the feasibility of pre-consolidation pressure distribution characteristic of western and southern coastal region, using correlation of unconfined compressive strength and preceding research equation. Pre-consolidation of western and southern region showed similar trends undrained shear strength and pre-consolidation pressure in proportion to unconfined compressive strength. Predicted results of U.S. NAVY. (1982) equation revealed a small error western 9.7 % and southern 0.4 %. Prediction correlation results of pre-consolidation using unconfined compressive strength revealed an error western 16.8 % and southern 0.7 %. It was reported that less than 20 percent of pre-consolidation pressure prediction result of Casagrande forecasting error. Estimates of pre-consolidation pressure are possible, before the standard consolidation test, because it was reported that less than 20 % of the forecasting errors of Casagrande.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1155-1158
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• 2006

This paper presents a study on the construction condition and environmental effect of deep soil mixing. Construction condition means the difference in unconfined compressive strength with respect to the depth and location of samples. Environmental effect means alkalinity diffused from soil stabilizer. The experimental results indicate that the unconfined compressive strength vary with respect to the depth, and doesn't show consistency pattern. So, in field application we must decide a mixing ratio enough to satisfy the least unconfined compressive strength. The difference in unconfined compressive strength with respect to the location of samples is negligible. The generation of alkalinity from soil stabilizer is reduced by permeating in non-improved soil and it is expected that the diffusion of alkalinity has no environmental effect on soil and ground water.

• Journal of the Korean GEO-environmental Society
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• v.20 no.5
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• pp.47-55
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• 2019

This study aims to provide basic data for soil packaging differing in accordance with the strength characteristics of mixed soil, using E.S.B. (Eco Soil Binder), an eco-friendly hardening agent, based on the type of soil. The soil used in this study is weathered granite soil readily collected in and around Korea, and is classified into SW, SP and SC according to soil classification systems. The test piece for the unconfined compressive strength test has dimensions of 50 mm in diameter and 100 mm in height, with the mix ratio of E.S.B. proportional to the weight of mixed soil changed from 5% to 10%, 15%, 20%, 25%, and 30%, where compactness of 90% and 100% were applied according to each condition to analyze the unconfined compressive strength characteristics at material ages of 3, 7, and 28 days. Also, the ratio of soil packaging standard strength and unconfined compressive strength was calculated to determine the optimal E.S.B. mix ratio, whereby the field applicability of the unconfined compressive strength using the estimation equation of ACI209R was evaluated.

• Geomechanics and Engineering
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• v.8 no.3
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• pp.361-375
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• 2015

Constructions over soft and loose soils are one of the most frequent problems in many parts of the world. Cement and cement-lime mixture have been widely used for decades to improve the strength of these soils with the deep soil mixing method. In this study, to investigate the freeze-thaw effect of sand improved by polymers (i.e., styrene-acrylic-copolymer-SACP, polyvinyl acetate-PVAc and xanthan gum) and fly ash, unconfined compression tests were performed on specimens which were exposed to freeze-thaw cycles and on specimens which were not exposed to freeze-thaw cycles. The laboratory test results concluded that the unconfined compressive strength increased with the increase of polymer ratio and curing time, whereas, the changes on unconfined compressive strength with increase of freeze-thaw cycles were insignificant. The overall evaluation of results has revealed that polymers containing fly ash is a good promise and potential as a candidate for deep soil mixing application.

• Magazine of the Korean Society of Agricultural Engineers
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• v.18 no.3
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• pp.4163-4170
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• 1976

This study was conducted to investigate the effect of starch as a retarder on the maximum dry density and the unconfined compressive strength of soil cement mixtures for varied starch contents (0-3%), cement contents (3-12%), and delay times (0-6hrs) in four soils. The experimental results obtained from maximum dry density and unconfined compressive strength tests are as follows: 1. Maximum dry density and unconfined compressive strength were increased greatly in soil cement mixtues rwhen starch was added as retarder but their value schanged according to soil varieties. 2. Maximum dry density showed at about 0.5 percent to 1.0 percent of starch in KY soil and about 2.0 percent to 2.5 percent in SS soil when delay time was changed in 2.4, and 6 hours in compaction test. 3. The larger content of cement was, the bigger effects of maximum dry density and compressive strength were in soil cement. mixtures. 4. As delay time changed 2.4, and 6 hours in compaction test, 7-day unconfined compressive strength showed the biggest value at about 0.5 percent of starch in KY soil and 2.0 percent in SS soil, and the maximum value of 28-day unconfined compressive strength showed at about 0.5 percent in KY soil and 1.5 percent in SS soil.