• Journal of the Korean Geotechnical Society
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• v.22 no.7
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• pp.37-44
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• 2006

This paper investigates strength characteristics and stress-strain behaviors of geogrid mixing reinforced lightweight soil. The lightweight soil was reinforced with geogrid in order to increase its compressive strength. Test specimens were fabricated by various mixing conditions including cement content, initial water content, air content and geogrid layer and then unconfined compression tests were carried out. From the experimental results, it was found that unconfined compressive strength as well as stress-strain behavior of lightweight soil was strongly influenced by mixing conditions. The more cement content that is added to the mixture, the greater its unconfined compressive strength. However, the more initial water content or the more air foam content, the less its unconfined compressive strength. It was observed that the compressive strength of reinforced lightweight soil increased reinforcing effect by the geogrid for most cases. Stress-strain relation of geogrid mixing reinforced lightweight soil showed a ductile behavior rather than a brittle behavior. In reinforced lightweight soil, secant modulus ($E_{50}$) also increased as its compressive strength increased due to the inclusion of geogrid.

• Geomechanics and Engineering
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• v.7 no.3
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• pp.247-261
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• 2014

Analytical and numerical modeling of soft or problematic soils stabilized with lime and cement require a number of soil parameters which are usually obtained from expensive and time-consuming laboratory experiments. The high shear strength of lime and cement stabilized soils make it extremely difficult to obtain high quality laboratory data in some cases. In this study, an alternative method is proposed, which uses the unconfined compressive strength and estimating functions available in literature to evaluate the shear strength parameters of the treated materials. The estimated properties were applied in finite element model to determine which estimating function is more appropriate for lime and cement treated granular soils. The results show that at the mid-range strength of the stabilized soils, most of applied functions have a good compatibility with laboratory conditions. However, application of some functions at lower or higher strengths would lead to underestimation or overestimation of the unconfined compressive strength.

• Journal of the Korean Geosynthetics Society
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• v.18 no.4
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• pp.253-262
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• 2019

This paper described the evaluation results on unconfined compressive strength characteristics of CLSM with paper sludge ash, in order to develop a CLSM that can prevent sewer pipe damage. The flowability test and the unconfined compressive strength test were performed according to mix design condition of CLSM. The flowability test result showed that the water content, which can satisfy the flowability criteria, was 24% to 32% according to the mix design condition. The results of unconfined compressive strength test showed that the strength incremental ratio was high between 1 and 7 days of curing time, and the strength at this time was more than about 50% of the strength at 28 days of curing time. The strength of CLSM was greatly influenced by fly ash. However, it was analyzed that the mixture of paper sludge ash is required when the reference strength of CLSM is considered. Although the strength of the high cement ratio was higher than that of the low cement, a cement ratio of 5% would be a reasonable mix design condition of CLSM.

• Geomechanics and Engineering
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• v.16 no.6
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• pp.599-608
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• 2018

This study investigates the feasibility of adopting the results of the UC (unconfined compression) test to assess the total cohesion of the unsaturated soil. A series of laboratory tests were conducted on samples of unsaturated lateritic soils of northern Taiwan. Specifically, the unconfined compression test was combined with the pressure plate test to obtain the unconfined compression strength and its matric suction of the samples. Soil samples were first compacted at designated water content and then subjected to the wetting process for saturation and the subsequent drying process to its target suction using the apparatus developed by the authors. The correlations among the matric suction, the unconfined compression strength and the total cohesion were studied. As a result, a simplified method to estimate the total cohesion using the unconfined compressive strength is suggested. The calculated results compare reasonably with the unsaturated triaxial test results. Current results show good performance; however, further study is warranted.

• Geomechanics and Engineering
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• v.19 no.4
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• pp.307-314
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• 2019

Light construction waste (LCW) particles are pieces of light concrete or insulation wall with light quality and certain strength, containing rich isolated and disconnected pores. Mixing LCW particles with soil can be one of the alternative lightweight soils. It can lighten and stabilize the deep-thick soft soil in-situ. In this study, the unconfined compressive strength (UCS) and its mechanism of Construction Waste Stabilized Lightweight Soil (CWSLS) are investigated. According to the prescription design, totally 35 sets of specimens are tested for the index of dry density (DD) and unconfined compressive strength (UCS). The results show that the DD of CWSLS is mainly affected by LCW content, and it decreases obviously with the increase of LCW content, while increases slightly with the increase of cement content. The UCS of CWSLS first increases and then decreases with the increase of LCW content, existing a peak value. The UCS increases linearly with the increase of cement content, while the strength growth rate is dramatically affected by the different LCW contents. The UCS of CWSLS mainly comes from the skeleton impaction of LCW particles and the gelation of soil-cement composite slurry. According to the distribution of LCW particles and soil-cement composite slurry, CWSLS specimens are divided into three structures: "suspend-dense" structure, "framework-dense" structure and "framework-pore" structure.

• Magazine of the Korean Society of Agricultural Engineers
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• v.23 no.4
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• pp.53-59
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• 1981

This experiment was carried out to find out the effectiveness of soil cement stabilization about the Song-I in Cheju province. The results are summarized as follows; 1.The increasing ratio of unconfined compressive strength according to the increment of cement content was markedly low compared with the weathered granite soil, so the effect of stabilization was low. 2.The moisture content of the sample of Song-I indicates the maximum unconfined compressive strength showed at the 5% or so of dry side than the optimum moisture content and the change of the unconfined compressive strength according to the change of moisture content was not sensitive compared with the weathered granite soil. 3.Generally the primary strength of curing age within 7 days of the sulfate resisting cement was low compared with the normal portland cement and the strength of 28 curing days showed a similar tendency, especially in case of Song-I, and it seemed that the sulfate resisting cement was a little more effective than the normal portland cement. 4.As the unconfined compressive strength of grain size controlled Song-I was low compared with the weathered granite soil, so the rate of weight loss by the durability test was great, therefore it was thought that the durability was weak.

• Geomechanics and Engineering
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• v.17 no.2
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• pp.195-206
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• 2019

The gypsiferous soils are significantly sensitive to moisture and the water has a severe destructive effect on them. Therefore, the effect of lime and silica fume addition on their mechanical properties, when subjected to water, is investigated. Gypsiferous soil specimens were mixed with 1, 2 and 3% lime and 1, 3, 5 and 7% silica fume, in terms of the dry weight of soil. The specimens were mixed at optimum moisture content and cured for 24 hours, 7 and 28 days. 86 specimens in the sizes of unconfined compression strength test mold were prepared to perform unconfined compressive strength and durability tests. The results proved that adding even 1% of each of these additives can lead to a 15 times increase in unconfined compressive strength, compared with untreated specimen, and this increases as the curing time is prolonged. Also, after soaking, the compressive strength of the specimens stabilized with 2 and 3% lime plus different percentages of silica fume was considerably higher than before soaking. The durability of the treated specimens increased significantly after soaking. Direct shear tests showed that lime treatment is more efficient than silica fume treatment. Moreover, it is concluded that the initial tangent modulus and the strain at failure increased as the normal stress of the test was increased. Also, the higher lime contents, up to certain limits, increase the shear strength. Therefore, simultaneous use of lime and silica fume is recommended to improve the geotechnical properties of gypsiferous soils.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.159-165
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• 2002

Soil cement which is a mixture of soil, cement, and water has a broad range of applications since it is economical, ecological, and easy to use, repair, and reinforce. Its applications include pavements, stabilization of slopes, retaining walls, and improvements of soft ground to name a few. Other types of chemicals are often added to increase its strength. This study investigated unconfined compressive strength of cured soil cement mixed with New Soil Chemical(NSC). The investigation involved laboratory experiments under various conditions including soil type, cement content, and ratios of water to NSC. Results of the study show that NSC enhanced the unconfined compressive strength significantly, and the degree of enhancement was varied with test conditions.

• Magazine of the Korean Society of Agricultural Engineers
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• v.27 no.4
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• pp.53-60
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• 1985

The plaster mixed to loam and sandy soil from 4 to 12 percent by dry soil weight, and the compaction, permeability, CBR, unconfined compressive strength and freezingthawing test were performed The results obtained are summarized as follows; 1.The coefficient of permeability reduced sharply at the plaster content of 4 percent, and in the CBR test, the swelling ratio reduced by the increment of plaster content. 2.The addition of plaster increased the unconfined compressive strength by the cementing effect, and it was found that the optimum plaster content, existed with the soil type, which showed the maximum strength 3.It was possible to enhance the unconfined compressive strength of the gypsum-lime-soil mixtures when the optimum content of plaster was mixed to the hydrated lime. 4.In case of sandy soil, the relative frost heave decreased with the mixture of plaster, however in loam soil, the relative frost heave began to increase at the plaster content of 12 percent than non-treated soil. Therefore the optimum plaster content existed for protecting frost heave by the different soil type. 5.The above summarized results make it possible to expect the effects such as improvement of soil properties, decrement of permeability, increment of unconfined compressive strength, and protection of frost heave, etc, therefore, it is considered that it is possible to it is plaster as sub-base materials of road.

• Journal of the Korean GEO-environmental Society
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• v.15 no.7
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• pp.31-38
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• 2014

For analysis of mechanics properties of soil cement, unconfined compressive strength has been proposed by existing case studies. In this study, mechanical changes with water content of silt, curing time and cement content were analyzed through unconfined compressive strength test. In addition, the changes for B factor by Abrams were compared with existing case studies after the prediction equations could be proposed about the unconfined compressive strength of admixed cement soil. Especially, the B constant factor was changed with soil characteristics and curing time. For analysis results of appropriateness status and unconfined compressive strength, consideration of variable form was titrated. The prediction equations at low plasticity silt admixed using the uniaxial compressive strength with applying Abrams's equation and considering cement content, curing time is proposed.