scholarly journals Performance of soils enhanced with eco-friendly biopolymers in unconfined compression strength tests and fatigue loading tests

2021 ◽  
Author(s):  
Jing Ni ◽  
Shan-Shan Li ◽  
Lei Ma ◽  
Xueyu Geng

Recently, biopolymers have emerged in soil stabilisation. The efficiency of biopolymers in groundimprovement is mainly dependent on biopolymer types, soil types, biopolymer contents, curing periods,thermal treatment and mixing methods. However, the effect of the initial moisture content during samplepreparation stages, on the mechanical behaviours of biopolymer-treated soils, has not been fullyunderstood. The first part of this study probed the role of initial moisture content, in treating Shanghaiclay with the xanthan gum by performing standard proctor compaction tests, Atterberg limit tests,unconfined compression strength (UCS) tests and microstructural analysis, while the second part contributedto capture the fatigue behaviours of the samples treated with an ideal moisture content by performingconstant-amplitude and stepping-amplitude fatigue loading tests. Our results showed that theimprovement appeared to occur from an average optimum moisture content for the treated soils (treatedoptimum), which was 3% wet of the untreated optimum. As the initial moisture content increased, theUCS values were elevated. However, there existed an ideal initial moisture content leading to the maximumstrengthening efficiency. For xanthan gum content (i.e., the mass of xanthan gum with respect tothe mass of dry soil) ranging from 1.0% to 5.0%, this ideal value was between 1.1 and 1.2 times the treatedoptimum. Our results also indicated that xanthan gum, as a biopolymer soil strengthener, was efficient inincreasing either fatigue life or bearing capacity, under repeated loading for xanthan gum-soil matrices,when compared to untreated soils. While the untreated soils failed at the stress level of only half the UCS,the xanthan gum-treated soils with a 3.0% xanthan gum content sustained at the end of the tests. Thesedata imply the potential use of xanthan gum in soil stabilisation, under repeated loads.

2021 ◽  
pp. 17-23
Author(s):  
Soewignjo Agus Nugroho ◽  
Ferry Fatnanta ◽  
Giri Prayoga

Tenayan Raya Subdistrict is an area that has a thickness of soft clay layer. Some cases of building failure were cracks and tilts due to high shrinkage of soil. Nearby is also a brick home industry center, where ashes are produced from bricks burning. Soil Improvement of Tenayan-Raya's Clay and utilization of brick ash will be carried out in this research. This study aims to stabilize the soil with lime and utilize the brick ash to improve shear strength and bearing capacity of the soil. The study was conducted in the laboratory by making several combinations of content clay, lime, and Brick Ash (BA), for the soil mixture which will be added with 10% ash brick. The effect of curing and soaked will also be seen for its rising on soil properties of Unconfined Compression Strength, and CBR laboratories. The influence of water will also be reviewed on the dry side, optimal moisture content, and wet side. The test results show that the Soil has Low Plasticity soil type category CL-ML symbols, according to the Unified classification. Increasing of strength due to stabilization with lime is obtained in conditions of water in optimal moisture content, where the addition of lime is 10% and 10% brick ash, was produced to increase the maximum value of Unconfined Compression Strength and CBR laboratory value. Curing setup time and saturation (soaked) also had affect the value of Unconfined Compressive Strength and CBR laboratory test. At longer time for curing, shear strength will rise proved by the value of UCS Test andbearing capacity value also increase that can be seen of the laboratory CBR test. Curing will make the shrinkage of clay reduced, this can be proven from differences value of Unconfined Compressive strength test between samples with and without soaked, are relatively small. 


2011 ◽  
Vol 250-253 ◽  
pp. 2124-2128
Author(s):  
Dong Xia Chen ◽  
Kai Yang ◽  
Yan Yang

Granite residual soils are often used as compacted soils in engineering structures such as pavement, embankments and backfills in Xiamen. Many geotechnical problems such as bearing capacity, lateral earth pressures and slope stability require an assessment of the shear strength of soil. Since the geotechnical properties of residual soils are impaired in contact with water, a series of unconfined compression tests are carried out on granite residual soils. Results of tests include effects of degree of compaction, moisture content, degree of saturation and cyclic wetting and drying on unconfined compression strength respectively. The increase in degree of compaction and compacting effort increases unconfined compression strength and the former greatly affects the strength. Moisture content of soils is higher than the optimum one of 2.5% for high strength and it is lower than optimum one of 2.5% for good plasticity in Xiamen areas. The degree of saturation of high unconfined compression strength normally ranges from 64% to 76%. In addition, cyclic wetting and drying causes loss of unconfined compression strength and the maximum loss commonly occurs at the first cycle and then is slowed down by the following cycles till the strength remains approximately constant.


Author(s):  
Anand J. Puppala ◽  
Louay N. Mohammad ◽  
Aaron Allen

Lime stabilization is often used to treat subgrade soils when they are soft and cohesive in nature. A study was conducted to investigate the engineering behavior, including the resilient and strength behaviors, of a lime-treated subgrade soil. The lime treatment procedure was adapted from the specifications of the Louisiana Department of Transportation and Development. Silty clay, a soil often found in Louisiana subgrades, is used as a base soil. A summary of various engineering properties of a lime-treated soil from resilient modulus, unconfined compression strength, and California bearing ratio (CBR) tests conducted at five moisture content and dry density levels is provided. Tests were also performed on the raw soil without lime treatment, and these results were compared with those of tests with the lime-treated soil. The comparisons indicate that the present lime treatment method results in an increase in strength and resilient modulus properties and a decrease in plasticity characteristics and plastic strains. A regression model with three constants was used to analyze the resilient modulus test results. The model constants are presented as functions of soil properties. Resilient modulus correlations that use either CBR or unconfined compression strength, moisture content, dry density, degree of compaction, and stresses as dependent attributes are developed.


2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Ali Ateş

Soil stabilization has been widely used as an alternative to substitute the lack of suitable material on site. The use of nontraditional chemical stabilizers in soil improvement is growing daily. In this study a laboratory experiment was conducted to evaluate the effects of waterborne polymer on unconfined compression strength and to study the effect of cement grout on pre-venting of liquefiable sandy soils. The laboratory tests were performed including grain size of sandy soil, unit weight, ultrasonic pulse velocity, and unconfined compressive strength test. The sand and various amounts of polymer (1%, 2%, 3%, and 4%) and cement (10%, 20%, 30%, and 40%) were mixed with all of them into dough using mechanical kneader in laboratory conditions. Grouting experiment is performed with a cylindrical mould of  mm. The samples were subjected to unconfined compression tests to determine their strength after 7 and 14 days of curing. The results of the tests indicated that the waterborne polymer significantly improved the unconfined compression strength of sandy soils which have susceptibility of liquefaction.


2011 ◽  
Vol 374-377 ◽  
pp. 1823-1826
Author(s):  
Zhong Yu Liu ◽  
Yong Gang Xue ◽  
Xi Jun Wang

In order to investigate the mechanical behaviors of lime-stabilized soils with small lime content, the specimens with 4%~8% lime content and 90%~95% degree of compaction are prepared, and then in use for the unconfined compression strength test, the diametral compression test and the compression resilience modulus test after they have cured in a standard curing room for 7 to 180 days respectively. These test results show that all of the unconfined compression strength, the splitting strength and the compression modulus of resilience increase with the degree of compaction and the curing time. Thereinto, the compression modulus of resilience does rapidly between 28 and 90 curing days, and the unconfined compression strength of the soil with 4% lime content does little after 28 curing days while the compression strengths and the splitting strengths of the other soils do quickly until 90 curing days. In addition, for a given degree of compaction, these strengths of the soils with the less lime content are potentially greater at the early curing time.


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