• Geomechanics and Engineering
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• v.3 no.3
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• pp.207-218
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• 2011

This article describes laboratory research done on strength evaluations for stabilized samples made of tropical fibrous peat. The stabilizing agents used were ordinary Portland cement (OPC) as binding agent and blast furnace slag (BFS) as additive. Stabilized samples were tested for their strength through unconfined compressive strength (UCS) and California bearing ratio (CBR). Different dosage rates of OPC and BFS were used in trial and error experiments for the most effective combination for stabilized peat samples that were at their natural moisture content. Stabilized trial samples were air cured for 90 days. After detecting the most effective dosage rate in the trial samples, their values were used to prepare CBR samples at their optimum moisture content (OMC). CBR samples were then air cured from 1 to 90 days and tested under un-soaked and soaked conditions. The most effective dosage rate for the stabilized peat samples was found to be close to when 75% for OPC and 25% of BFS per total weight of OPC, and BFS. As an example, if 11.25% OPC, and 3.75% BFS are mixed with peat and compacted at their OMC and air cured for 90 days, stabilized peat will have an increase in CBR of 0.8% to 45 % for un-soaked and 20% for soaked conditions.

• Advances in concrete construction
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• v.4 no.3
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• pp.207-220
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• 2016

The objective of this study was to evaluate the influence of recycled materials, namely, shredded scrap tire (SST), reclaimed asphalt pavement (RAP) and class C fly ash (CFA) on compressive and tensile strength of concrete. Either SST or RAP was used as an aggregate replacement and class C fly ash (CFA) as Portland cement replacement for making concrete. A total of two types of SST and RAP, namely, chips and screenings were used for replacing coarse and fine aggregates, respectively. A total of 26 concrete mixes containing different replacement level of SST or RAP and CFA were designed. Using the mix designs, cylindrical specimens of concrete were prepared, cured in water tank, and tested for unconfined compressive strength (UCS) and indirect tensile strength (IDT) after 28 days. Experimental results showed aggregate substitution with SST decreased both UCS and IDT of concrete. On the contrary, replacement of aggregate with RAP improved UCS values. Specimens containing RAP chips resulted in concrete with higher IDT values as compared to corresponding specimens containing RAP screenings. Addition of 40% CFA was found to improve UCS values and degrade IDT values of SST containing specimens. Statistical analysis showed that IDT of SST and RAP can be estimated as approximately 13% and 12% of UCS, respectively.

• Journal of Ocean Engineering and Technology
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• v.19 no.6 s.67
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• pp.44-49
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• 2005

This paper investigates strength characteristics and stress-strain behaviors of unreinforced and reinforced lightweight soils. Lightweight soil, composed of dredged soil, cement, and air-foam, was reinforced by a waste fishing net, in order to increase its compressive strength. Test specimens were fabricated by various mixing conditions, such as cement content, initial water content, air content, and waste fishing net; then, unconfined compression tests were carried out on these specimens. From the test results, it was shown that reinforced lightweight soil had different behavior after failure, even though it had similar behavior as unreinforced lightweight soil before failure. The test results also showed that stress became constant after peak strength in reinforced lightweight soil, while the stress decreased continuously in unreinforced lightweight soil. It was observed that the strength was increased due to reinforcing effect by the waste fishing net for most cases, except high water content greater than $218\%$. In the case of high water content, a reinforcing effect is negligible, due to slip between waste fishing net and soil particles. In reinforced lightweight soil, secant modulus (E50) was increased, due to the inclusion of waste fishing net.

• Geomechanics and Engineering
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• v.14 no.3
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• pp.301-306
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• 2018

Stabilization of clayey soil has been studied from past to present by mixing different additives to the soil to increase its strength and durability. In recent years, there has been an increasing interest in stabilization of soils with natural pozzolans. Despite this, very few studies have investigated the impact of pozzolanic additives under freeze-thaw cycling. This paper presents the results of an experimental research study on the durability behavior of clayey soils treated with lime and perlite. For this purpose, soil was stabilized with 6% lime content by weight of dry soil (optimum lime ratio of the the soil), perlite was mixed with it in 0%, 5%, 10%, 20%, 25% and 30% proportions. Test specimens were compacted in the laboratory and cured for 7, 28 and 84 days, after which they were tested for unconfined compression tests. In addition to this, they were subjected to 12 closed system freeze-thaw cycles after curing for 28 days. The results show that the addition of perlite as a pozzolanic additive to lime stabilized soil improves the strength and durability. Unconfined compressive strength increases with increased perlite content. The findings indicate that using natural pozzolan which is cheaper than lime, has positive effect in strength and durability of soils and can result cost reduction of stabilization.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.1
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• pp.3685-3701
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• 1975

This study was conducted to investigate the strength of soil cements for varied molding water content and cement content(3,6,9,12%) in four cementstabilized soils(KY: sand, MH: sad, SS: sandy loam, JJ: loam). The eoperimental results obtainedfrom unconfined compressive strength tests are asfollows: 1. The optimum moisture content increased in accordance with the increase of the cement while maximum dry density didn't change uniformly. 2. The moisture content for maximum strength was higher than the optimum moisture content in the higher cement content. Moisture-density curves showed a dull peak in the higher cement contents, on the other hand, a sharp peak in the lower cement contents. 3. In molding the specimen with the approximate optimum moisture content, the maximum strength showed at the wet side of the optimum moisture content. 4. SS and JJ maybe used as cement-stabilized base of road to require 300PSI of compressive strength cured seven days, but MH and KY may be not adequate. 5. In soil cement, the better the grain size distribution was, the stronger the compressive strength was itn general. 6. The relation between 28-day strengh and 7-day strength in the cementstabilized four soils may be expressed as follows: q28=1.55q7+1.5 in which q28:28-day strength. q7:7-day strength.

• Magazine of the Korean Society of Agricultural Engineers
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• v.22 no.3
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• pp.46-59
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• 1980

This study was conducted to obtain the most effective distribution of grain size and the optimum lime content for lime-soil stabilization. To achieve the aim, the change of consistency, the characteristics of compaction and unconfined compressive strength were tested by adding of 0, 4, 6, 8, 10 and 12 percent lime by weight for all soils adjusted by given ratios of sand to clay. The results obtained were as follows; 1. There was a tendency that the plasticity index of lime-soil mixture was decreased by increasing the amount of lime, whereas the liquid limit was varied irregularly and the plastic limit was increased. 2. With the addition of more lime, the optimum moisture content of lime-soil mixture was increased, and the maximum dry density was decreased. 3. The optimum lime content of lime-soil mixture was varied from soil to soil, and the less amount of small grain size, the less value of optimum lime content. 4. The optimum distribution of grain size for lime-soil mixture was in the soil, having the ratio of about 60 percent of cohesive clay and about 40 percent of sand by weight. 5. In the soil having fine grain size, the effect of curing appeared for long periods of time, whereas the increasing rate of unconfined compressive strength was great on the soil of coarse grain size in the earlier stage of curing period.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.4
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• pp.63-70
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• 2007

The soil samples used in this study were prepared with the residual granite soils passed through the #4 sieve and obtained from Pocheon in Gyeonggi-Ki do. Specifically, five types of samples were prepared. Sample A which is a natural state soil was classified as SM according to the uses. Samples of B, C, D, and E were prepared by mixing Sample A with bentonite and were classified as SC according to the uses. The plasticity indexes of samples B, C, D, and E were 15, 25, 30, and 40, respectively. The specimens, whose dimensions are 100mm by 127.5mm, were prepared by A method of ASTM D 698 with the Proctor mold. In experiments, the loading with the 1%/min was applied. Four different disk diameters, 13mm, 26mm, 38mm, and 52mm were used in the Improved Unconfined Penetration (IUP) tests. To compare the tensile strengths, the split tensile tests were also conducted on the same specimens used for the IUP tests. To find out the effects of moisture contents, plasticity Index of specimens on the tensile strength, six different water contents were used for making a specimen.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.3
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• pp.129-140
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• 2013

Bottom Ash is industrial by-product from a thermoelectric power plant. An immense quantities of bottom ash have increased each year, but most of them is reclaimed in ash landfill. In this study, in order to raise recycling rate of Bottom Ash, it is suggested to cure Bottom Ash (BA) mixtures mixed with cement, lime, Fly Ash (FA), and oyster shell (OS). Mixtures of 5~20 % mixing ratio had been cured for 1, 3, 7, 14, and 28 days using sealed curing and air-dry curing method. Unconfined compressive strength test was conducted to determine strength and deformation modulus ($E_{50}$) change for mixtures as mixing ratio and curing day, water contents of mixtures were measured after test. As a result, strength and $E_{50}$ were increased as mixing ratio and curing days, but values and tendencies of them appeared in different as kind of mixture, mixing ratio, curing method, and curing days. The results showed the addition of cement, lime, Fly Ash, and oyster soil in Bottom Ash could improved strength and $E_{50}$ and enlarge its field of being used.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.3
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• pp.111-119
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• 2005

The objective of this study is to predict fracture movements accurately and reliably by nonlinear analysis of the response of RC shear wall or RC flange sections. Hognestad's and Vallenas's theories are used for concrete model and Ramberg-Osgood's theory is used for steel model. Non-linear analysis considering confined concrete and unconfined concrete is performed. Mander's Fiber Approach Section analysis, new strain profile considering the Gamma factor are used to this section analysis. The section analysis considering cases of precracked, uncracked, boundary warping and shear warping is performed.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09b
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• pp.147-151
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• 2010

In this study, the clay specimen of Busan-Gyeongnam region was used for unconfined compression test to compare the relationship formula between elasticity modulus at peak($E_f$), elasticity modulus at $q_u$/2($E_{50}$), and cohesion when the sample breaks down by region and by level of cohesion. As the result, the regional results were found to be in the range of $E_f$ = 14c~47c and $E_{50}$ = 43c~137c; by cohesion, the results for very soft ground was $E_f$ = 15c~40c and $E_{50}$ = 54c~101c, $E_f$ = 13c~63c and $E_{50$ = 40c~147c for soft ground, $E_f$ = 18c~47c and $E_{50}$ = 57c~144c for medium ground, and $E_f$ = 25c~45c and $E_{50}$ = 68c~115c for solid ground. The average of the relationship formula between elasticity modulus-cohesion for the clay used in this study was $E_f$ = 32c, $E_{50}$ = 93c. This is 2.5~5 times smaller than the existing relationship formula.