scholarly journals The California Bearing Ratio and Pore Structure Characteristics of Weakly Expansive Soil in Frozen Areas

2020 ◽  
Vol 10 (21) ◽  
pp. 7576
Author(s):  
Tianguo Li ◽  
Lingwei Kong ◽  
Bingheng Liu
Keyword(s):  
Pore Size ◽  
Expansive Soils ◽  
Expansive Soil ◽  
California Bearing Ratio ◽  
Dominant Factor ◽  
Freeze Thaw ◽  
Pore Size Distributions ◽  
Compaction Energy ◽  
Gradual Variation ◽  
Compaction Degree

The California Bearing Ratio (CBR) of weakly expansive soil is specially relevant to its expansibility. The mechanisms affecting the bearing strength, in terms of the CBR, of weakly expansive soil that could be used as embankments filler are worth studying. In the present study, the effects of compaction energy on the compaction characteristics and CBR value were investigated. Additionally, the pore size distributions of soils with different compaction degrees were studied with nuclear magnetic resonance (NMR), and the effect of freeze–thaw cycles on the pore size distribution of soils with different compaction degrees was considered. Subsequently, the mechanisms influencing the CBR were analyzed at both the macroscale and microscale. A linear relationship between the CBR value and compaction degree was determined, characterizing the gradual variation of expansive soils with different moisture contents. With increasing freeze–thaw cycles, the volume of micropores decreased and mesopores increased, causing the CBR value to decrease. The expansion was a dominant factor for the CBR values. The CBR values rose with an increase in micropores and decreased with an increase in pore volume. It was considered that the tested weakly expansive soil could be used as an embankment filler in frozen areas.

scholarly journals Experimental Study on Dynamic Resilient Modulus of Lime-Treated Expansive Soil

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Zheng Lu ◽  
Yang Zhao ◽  
Shaohua Xian ◽  
Hailin Yao
Keyword(s):  
Moisture Content ◽  
Environmental Changes ◽  
Resilient Modulus ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
The Stability ◽  
Compaction Degree

Dynamic resilient modulus is the design index of highway subgrade design code in China, which is significantly affected by the traffic loads and environmental changes. In this study, dynamic triaxial tests were conducted to investigate the influence of moisture content, compaction degree, cyclic deviator stress, and confining pressure on lime-treated expansive soil. The suitability of UT-Austin model to lime-treated expansive soils was verified. The results indicate that the dynamic resilient modulus of lime-treated expansive soils increases nonlinearly with the increase of compaction degree, while decreases nonlinearly with the increase of dynamic stress level. The dynamic resilient modulus decreases linearly with the increase of moisture content and increases linearly with the increase of confining pressure. Moreover, the moisture content has a more significant effect on the dynamic resilient modulus of lime-treated expansive soil. Therefore, it is necessary to ensure the stability of soil humidity state and its excellent mechanical properties under long-term cyclic loading for the course of subgrade filling and service. Finally, the calculated results of the UT-Austin model for dynamic resilient modulus show a good agreement with the test results.

scholarly journals Effect of Compaction Energy on Engineering Properties of Expansive Soil

2017 ◽  
Vol 3 (8) ◽  
pp. 610 ◽  
Author(s):  
Sadam Hussain
Keyword(s):  
Expansive Soils ◽  
Energy Levels ◽  
Expansive Soil ◽  
Substantial Improvement ◽  
Engineering Properties ◽  
Engineering Structures ◽  
Expansive Clays ◽  
Swell Potential ◽  
Compaction Energy ◽  
Strength And Deformation

Swelling of expansive clays is one of the great hazards, a foundation engineer encounters. Each year expansive soils cause severe damage to residences, buildings, highways, pipelines, and other civil engineering structures. Strength and deformation parameters of soils are normally related to soil type and moisture. However, surprisingly limited focus has been directed to the compaction energy applied to the soil. Study presented herein is proposed to examine the effect of varying compaction energy of the engineering properties i.e. compaction characteristics, unconfined compressive strength, California bearing ratio and swell percentage of soil. When compaction energy increased from 237 KJ/m3 to 1197 KJ/m3, MDD increased from 1.61 g/cm3 to 1.75 g/cm3, OMC reduced from 31.55 percent to 21.63 percent, UCS increased from 110.8 to 230.6 KPa, and CBR increased from mere 1 percent to 10.2 percent. Results indicate substantial improvement in these properties. So, compacting soil at higher compaction energy levels can provide an effective approach for stabilization of expansive soils up to a particular limit. But if the soil is compacted more than this limit, an increase in swell potential of soil is noticed due to the reduction in permeability of soil.

Influence of compaction conditions on pore-size distribution and saturated hydraulic conductivity of a glacial till

2000 ◽  
Vol 37 (6) ◽  
pp. 1184-1194 ◽  
Author(s):  
Y Watabe ◽  
S Leroueil ◽  
J -P Le Bihan
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Void Ratio ◽  
Glacial Till ◽  
Degree Of Saturation ◽  
Size Distributions ◽  
Pore Size Distributions ◽  
Compaction Degree

The paper examines the hydraulic conductivity of a nonplastic till from northern Quebec. It is shown that the hydraulic conductivity is strongly influenced by the compaction degree of saturation, and the variation of hydraulic conductivity with void ratio is influenced by compaction conditions. Determination of pore-size distributions and microphotographs provide evidence that changes in hydraulic conductivity are related to the fabric of the compacted specimens and macroporosity developing when the soil is compacted at degrees of saturation less than that at the optimum.Key words: till, hydraulic conductivity, microfabric.

The Tests on the Lime-Treated Expansive Soils Compaction Characteristics

2013 ◽  
Vol 405-408 ◽  
pp. 548-553
Author(s):  
Xin Zhong Wang ◽  
Rui Liu ◽  
Shu Jun Peng
Keyword(s):  
Water Content ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Dry Density ◽  
Maximum Dry Density ◽  
Compaction Characteristics ◽  
Lime Content ◽  
Compaction Energy ◽  
Wetting Time ◽  
Lower Height

The compaction characteristics of the lime-treated expansive soils from the planning airport in China's Ankang were studied through the heavy compaction tests. The results show that all these elements such as lime content, water content, soil height, wetting time have a certain effect on dry density. As the lime quality ratio increases, the optimum water content under heavy compacting standard of improved soils increases but the maximum dry density decreases. With the increase of lime content, the effect of water content on dry density decreases while the water content near to its optimum value. Soils with the lower height have higher dry density when compaction energy, lime content and water content unchanged. As the wetting time increases, the maximum dry density shows a decreasing tendency until after 48 h it remained stable. It indicates that with the same lime content the order of primary factors influence on dry density are water content, wetting time, soil height. Finally, the lime stabilizing principle to expansive soil is explained through by applying scanning electron microscope technique.

scholarly journals Application of Optimum Compaction Energy in the Development of Bricks Made with Construction Trash Soils

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
T. Lopez-Lara ◽  
C. L. Gonzalez-Vega ◽  
J. B. Hernandez-Zaragoza ◽  
E. Rojas-Gonzalez ◽  
D. Carreón-Freyre ◽  
...  
Keyword(s):  
Specific Energy ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Generalized Solution ◽  
Energy Aspect ◽  
Density Values ◽  
Compaction Energy

In general, bricks frequently show different densities and therefore different resistances because the compaction energy is not considered in their production. Expansive soils represent a problem for light buildings over them because of volumetric instability. A generalized solution has been to extract them and substitute them by inert soil; thus they become construction trash. So, in this work the compaction energy aspect and the use of construction trash soils in the elaboration of resistant masonry bricks of homogeneous and controlled density are a new contribution in the production of bricks of better quality. First, the soil was stabilized with CaOH which leads to a decrease in its volumetric changes. Then, they were compacted with a specific energy for obtaining an optimal and maximum controlled density to ensure an increase in strength. Our results show that two optimal compaction energies can be considered with respect to the variation of optimum moisture in masonry bricks of expansive soil stabilized with lime. The first is when the optimal humidity reaches its smallest value (integrated soil lumps) and the second is when humidity increases (disintegrated soil lumps), after reaching its lowest value. We also conclude that high compaction energy does not improve density values.

scholarly journals Study on Soil-Water Characteristics of Expansive Soil under the Dry-Wet Cycle and Freeze-Thaw Cycle considering Volumetric Strain

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Lisi Niu ◽  
Aijun Zhang ◽  
Jiamin Zhao ◽  
Wenyuan Ren ◽  
Yuguo Wang ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Expansive Soils ◽  
Volumetric Strain ◽  
Expansive Soil ◽  
Volumetric Water Content ◽  
Dry Density ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

This paper targets the expansive soils in Heilongjiang and Ankang to explore the influence of initial dry density, dry-wet cycle, and freeze-thaw cycle on the soil-water characteristics. The centrifuge method was used to obtain the soil-water characteristic curves (SWCCs) with different conditions. The volumetric strain of SWCC was modified based on the shrinkage test, and the corresponding fitting equations considering different factors were established. The results show that the volumetric water content is modified to consider the volume shrinkage effect of expansive soil, and the modification is more obvious in the high matric suction range. The smaller the initial dry density is, the worse the water-holding capacity of the sample is, and the smaller the air intake value is. The greater the time of the dry-wet cycle is, the greater the saturated volumetric water content of the sample is, and the corresponding water-holding capacity is significantly reduced. When the dry-wet cycle increases to a certain extent, the structure becomes stable. With the increase of the freeze-thaw cycle, the saturated volumetric water content first decreases and then increases. Similarly, after several times of the freeze-thaw cycle, the structure is basically stable. The fitted Gardner model equations under different conditions were proved to be able to describe the SWCCs of the two targeted expansive soils.

CHARACTERIZATION OF PORE SIZE DISTRIBUTIONS USING NON-NEWTONIAN FLUIDS

2020 ◽  
Author(s):  
Scott C. Hauswirth ◽  
◽  
Majdi Abou Najm ◽  
Christelle Basset
Keyword(s):  
Pore Size ◽  
Newtonian Fluids ◽  
Size Distributions ◽  
Pore Size Distributions

scholarly journals Strength and Microscopic Damage Mechanism of Yellow Sandstone with Holes under Freezing and Thawing

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Huren Rong ◽  
Jingyu Gu ◽  
Miren Rong ◽  
Hong Liu ◽  
Jiayao Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Pore Size ◽  
Power Function ◽  
Damage Mechanism ◽  
Uniaxial Compression Test ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Microscopic Damage

In order to study the damage characteristics of the yellow sandstone containing pores under the freeze-thaw cycle, the uniaxial compression test of saturated water-stained yellow sandstones with different freeze-thaw cycles was carried out by rock servo press, the microstructure was qualitatively analyzed by Zeiss 508 stereo microscope, and the microdamage mechanism was quantitatively studied by using specific surface area and pore size analyzer. The mechanism of weakening mechanical properties of single-hole yellow sandstone was expounded from the perspective of microstructure. The results show the following. (1) The number of freeze-thaw cycles and single-pore diameter have significant effects on the strength and elastic modulus of the yellow sandstone; the more the freeze-thaw cycles and the larger the pore size, the lower the strength of the yellow sandstone. (2) The damage modes of the yellow sandstone containing pores under the freeze-thaw cycle are divided into five types, and the yellow sandstone with pores is divided into two areas: the periphery of the hole and the distance from the hole; as the number of freeze-thaw cycles increases, different regions show different microscopic damage patterns. (3) The damage degree of yellow sandstone is different with freeze-thaw cycle and pore size. Freeze-thaw not only affects the mechanical properties of yellow sandstone but also accelerates the damage process of pores. (4) The damage of the yellow sandstone by freeze-thaw is logarithmic function, and the damage of the yellow sandstone is a power function. The damage equation of the yellow sandstone with pores under the freezing and thawing is a log-power function nonlinear change law and presents a good correlation.

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