Study of Mutual Improvement of Completed Weathered Phyllite and Red Clay Based on Neutralization Effects of Swelling and Shrinkage Deformation

Zhao, Xiushao; Yang, Qian; Rao, Jianglong; Geng, Daxin; Tan, Zhouyong

doi:10.32604/jrm.2021.015854

Cited by 5 publications

(4 citation statements)

References 39 publications

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“…The disintegration of soil is closely related to the mineral composition, and the mineral content of the two type soils is determined by a semi-quantitative XRD test, as shown in Table 3. The phyllite soil contains montmorillonite, illite, and chlorite, which are three kinds of hydrophilic clay minerals accounting for 40.6% of the total mass of phyllite soil (montmorillonite is a typical expansive mineral) and which are prone to swell and deformation after being soaked in water [28]. According to the laboratory free expansion test, the free expansion ratio of phyllite soil reaches 19.4%.…”

Section: Influence Of Mineral Composition and Particle Size On Disint...mentioning

confidence: 99%

“…In this paper, a novel method is proposed by adding cement and red clay simultaneously to phyllite soil to improve its permeability and disintegration characteristics. Previous studies have shown that red clay can significantly improve the direct subgrade-bearing capacity of phyllite soil [27], and phyllite soil can significantly reduce the cracks caused by the wetting-drying cycle of red clay [28]. The seven-day saturated unconfined compressive strength of a cement-treated phyllite blended with red clay can be greater than 350 kPa [29].…”

Section: Introductionmentioning

confidence: 99%

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Permeability and Disintegration Characteristics of Composite Improved Phyllite Soil by Red Clay and Cement

Zhao

Yang

et al. 2022

Minerals

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The bearing capacity of the phyllite soil subgrade can be greatly improved by red clay, but the water stability of the modified soil is still poor. Hence, the blended soil has been found to be unsuitable for the construction of high-speed railways. This paper proposes an innovative scheme, by adding appropriate amounts of cement and red clay concurrently, to improve phyllite soil, which achieves a higher bearing capacity of the subgrade immediately after compaction, while also solving the problem of insufficient water stability. Laboratory tests of the permeability and disintegration characteristics of phyllite soils improved by cement, red clay, and both were carried out. The test results show that the permeability coefficient and maximum disintegration rate of soil can be improved effectively by using both red clay and cement. It was found that the optimal combination scheme is to add 3% cement and 40% red clay to phyllite soil by mass. Under the optimal scheme, the permeability coefficient, maximum disintegration rate, and disintegration rate of the improved soil decreased by 90.02%, 90.30%, and 99.02%, respectively, compared with the phyllite soil. The microscopic study shows that the mechanism of red clay blending with phyllite is that the finer particles of red clay infill the pores among the phyllite particles, thus reducing its permeability coefficient. The mechanism of adding cement to the blending soil mainly results from the production of hard-setting new materials and the formation of a cementation network among the soil particles, which not only increases the shear strength of the soil, but also reduces the permeability coefficient and the maximum disintegration ratio of the soil. This work makes full use of the complementary characteristics of red clay and phyllite soil and the advantages of hard-setting new materials, which will provide a new idea for soil improvement of the phyllite soil in the future.

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Section: Influence Of Mineral Composition and Particle Size On Disint...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Permeability and Disintegration Characteristics of Composite Improved Phyllite Soil by Red Clay and Cement

Zhao

Yang

et al. 2022

Minerals

Self Cite

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“…There are no specific reference opinions on the relaxation requirements for compaction and moisture content, and the engineering characteristics of red clay fillers vary in different regions [ 12 , 13 ]. Therefore, it is urgent to start from the basic needs of filling red clay embankments, exploring the relationship between the basic physical and mechanical indicators of Guangxi red clay and the changes in compaction and moisture content and providing guidance for engineering construction [ 14 , 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

Influence Mechanism of Water Content and Compaction Degree on Shear Strength of Red Clay with High Liquid Limit

Feng,

Teng,

Wang

2023

Materials

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To investigate the influencing factors and mechanisms of shear strength of red clay with a high liquid limit, which was selected at different milepost locations based on the Nanning Bobai Nabu Section Project of the Nanning Zhanjiang Expressway, the basic physical properties of red clay were determined using a liquid plastic limit test, compaction test, inductively coupled plasma optical emission spectrometer (ICP-OES), and X-ray fully automatic diffractometer (XRD). Red clay with a high liquid limit was selected. Furthermore, the direct shear test was used to study the effect of different water contents and compaction degrees on the shear strength. The experimental results demonstrate that under the same compaction degree, the shear stress of the soil sample increases significantly with an increase in normal stress, and the greater the water content, the smaller the shear stress of the soil sample. At 200 kPa, the shear strength of soil samples with 24% water content is 57%, 46%, and 35% of the shear strength of soil samples with 15% water content under different compaction degrees(K) of 86%, 90%, and 93%, respectively. Under the same moisture content, the shear stress of the soil sample shows an increasing trend with an increase in the degree of compaction, and the greater the compaction degrees, the greater the shear stress of the soil sample. The cohesion c and internal friction angle φ of soil samples increase with an increase in the compaction degree, but the increase in cohesion c is also affected by the water content. Under the condition of low water content, the cohesion c of soil samples can be increased by 1.06 times when the water content is 15% and by 0.47 times when the water content is 18%. Under the condition of high water content, the cohesion c of soil samples with 21% water content only increases by 0.3 times, and that with 24% water content only increases by 0.35 times.

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“…The traditional methods of improving weathered phyllite with cement or lime mainly consider the longterm strength and long-term stability of subgrade fill, but a significant amount of cement or lime is required to achieve this [9,10]; Using red clay to improve CWP soil mainly considered the immediate strength [27], and the method can not only reduce the expansibility of CWP, but also reduce the fissures in red clay [29]. However, this type of improvement method is only suitable for ordinary railway subgrade applications but cannot satisfy the subgrade requirements for the high-speed railway.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Improvement Effects of Completely Weathered Phyllite Using Red Clay and Cement for High-Speed Railway Embankments

Zhao¹,

Rao²,

Yang³

et al. 2022

Journal of Renewable Materials

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Completely weathered phyllite (CWP) has the characteristics of difficult compaction, low shear strength after compaction and large settlement after construction. The traditional improvement method using a single agent of red clay or cement for CWP satisfies the subgrade requirements for ordinary railway, but cannot meet the requirements of immediate strength and long-term post-construction settlement of high-speed railway at the same time. A series of experimental investigations were undertaken for the blended CWP soils, with three additives used. The first additive was red clay, the second was cement and the third was a combination of both red clay and cement at various portions. Results of consolidation test and shear strength test carried out for the treated CWP soils show that: 1) The effect of cement on improving the compression modulus of CWP is much better than that of red clay; 2) The settlement of an embankment of 10 m high formed by blended soil of CWP with 3% cement can be controlled within 15 mm, while the settlement will be 25.15 mm for the same embankment of blended soil of CWP with 40% red clay; 3) The shear strength and ultimate bearing capacity of CWP improved by red clay are much better than those of 5% cement; 4) The ultimate bearing capacity of CWP improved by 40% red clay is 3.42 times of that by 3% cement and 2.95 times by 5% cement. Furthermore, the bearing capacity of CWP when improved by red clay can meet railway subgrade requirements immediately after compaction, while cement improved CWP needs a curing time of 1 day or longer. This is an impediment to rapid construction process. The improvement mechanism of red clay is mainly filling effect and grading improvement effect, while the improvement mechanism of cement is mainly hardening reaction, which produces high strength material to cement. It is found that 40% red clay and 3% cement treated CWP, which is considered to be optimum, can meet the subgrade requirements of both immediate bearing capacity and long-term post-construction settlement for the high-speed railway.

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Study of Mutual Improvement of Completed Weathered Phyllite and Red Clay Based on Neutralization Effects of Swelling and Shrinkage Deformation

Cited by 5 publications

References 39 publications

Permeability and Disintegration Characteristics of Composite Improved Phyllite Soil by Red Clay and Cement

Permeability and Disintegration Characteristics of Composite Improved Phyllite Soil by Red Clay and Cement

Influence Mechanism of Water Content and Compaction Degree on Shear Strength of Red Clay with High Liquid Limit

Experimental Study on Improvement Effects of Completely Weathered Phyllite Using Red Clay and Cement for High-Speed Railway Embankments

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