Study on stress-strain-resistivity and microscopic mechanism of red mud waste modified by desulphurization gypsum-fly ash under drying-wetting cycles

Salih, Wdah.T.; Wang, Yu; Dong, Xiaoqiang; Hao, Wen

doi:10.1016/j.conbuildmat.2020.118772

Cited by 26 publications

(15 citation statements)

References 44 publications

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“…9 . In current study, residual strength was determined following Salih et al 38 who suggested that the residual strength is attained if a relatively constant shear stress is measured for more than half hour. However, a constant value of residual strength was not observed due to the stress fluctuation in the shearing process, even the specimen was sheared at a large displacements.…”

Section: Resultsmentioning

confidence: 99%

“…It should be noted that the significance of microstructure in evaluation the deformation and shear strength characteristics of soil 38 , 52 . Furthermore, the change in the microstructure of slip zone soils during the shearing process is complicated 53 and the macroscopic mechanical properties of soils could be directly related to its microstructure 54 , 55 .…”

Section: Resultsmentioning

confidence: 99%

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A mechanical insight into the triggering mechanism of frequently occurred landslides along the contact between loess and red clay

Lian

Wang

et al. 2021

Sci Rep

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The triggering mechanism and movement evolution of loess-red clay landslides, which occurred frequently along the contact between the loess and red clay on the Loess Plateau, are closely related to the mechanical properties of the contact surface. This work presents an experimental investigation on loess, clay and loess-red clay interlaminar (LRCI) samples obtained from a typical loess-red clay landslide in northern part of Shaanxi province of China, using a series of ring shear tests, microscopic observation and scanning electron microscopy tests, in an attempt to explore the mechanical behavior of loess, clay and LRCI samples with variation in moisture content, normal stress and shear rate. The results revealed that for all specimens, both the peak shear strength $$\tau_{p}$$ τ p and the residual shear strength $$\tau_{r}$$ τ r decreased with increasing moisture content, among which, moisture content has the greatest influence on the $$\tau_{p}$$ τ p and $$\tau_{r}$$ τ r of red clay, followed by the LRCI specimen, and the loess specimen is least affected by moisture content. Meanwhile, exponential functions describing the correlations between shear strength and moisture content of LRCI, red clay and loess specimens were proposed. Furthermore, the macroscopic morphological characteristics and the microstructure of shear surface obtained from the LRCI specimens showed that a localized water accumulation was built up within the shear surface as the water content increases to some extent, and a high degree of liquefaction developed within shear surface when the moisture content reached to the saturate degree. The microstructural observation on LRCI specimen suggested that the shear surface became smoother and the larger percentage of small-sized pores was observed with moisture content. Accordingly, the built-up excess pore water pressure during shearing is difficult to be dissipated due to a close structure of small-sized pores. Due to the low permeability, high pore-water pressure built up within the shear zone and the increase in the fine particle content, the LRCI soils with a high saturation degree shows the potential for the localized liquefaction within shear zone, which further provides a scientific explanation for the triggering mechanism of loess-red clay landslides with high-speed and long- run out.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

A mechanical insight into the triggering mechanism of frequently occurred landslides along the contact between loess and red clay

Lian

Wang

et al. 2021

Sci Rep

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“…Rock is an important building material used in many engineering applications, including water conservancy and hydropower engineering and tunnel engineering [1][2][3][4][5][6][7][8][9]. In such applications, the rock will inevitably be immersed in water for short to long durations [10][11][12][13][14][15], altering its mechanical properties. The tensile strength of rock is much lower than its compressive strength, and water-bearing rock is often subjected to tensile failure under loading [16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Immersion Effects of Pressure Water on the Tensile Characteristics of Sandstone Samples

Yin

Chen

et al. 2021

Geofluids

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In this study, Brazilian splitting tests were conducted on sandstone samples subjected to drying and immersing at water pressures of 0, 1, and 3 MPa (immersion duration of 120 h). Investigation of the immersion effects of pressure water on the tensile characteristics of the samples revealed that their tensile strengths decreased with the immersion water pressure. Relative to a sandstone sample subjected to drying alone, immersing at water pressures of 0, 1, and 3 MPa reduced the tensile strength by 12.96%, 19.03%, and 30.16%, respectively. Although the immersed samples experienced splitting failure indicative of obvious brittle failure characteristics, decreases in the postpeak stress reduction rate with immersion water pressure revealed that the intensity of brittle failure weakened with pressure. Based on the obtained data, the deformation evolution process of the sandstone samples could be divided into five stages: deformation adjustment, formation of local deformation zones, local deformation zone propagation, failure surface formation, and sample failure. The water pressure aggravated the physicochemical reactions between water and the hydrophilic minerals in the sandstone, promoting argillisation, dissolution, and loss of hydrophilic minerals and interparticle cementitious materials. As a result of these immersion micromechanisms, the deterioration of the sandstone samples increased with the immersion water pressure, with the average porosities of the fracture surfaces at 0, 1, and 3 MPa increasing by 142.86%, 368.37%, and 593.88%, respectively, relative to the dried sample. As a result of these morphological changes, the sandstone samples subjected to water pressure immersion failed at small axial stresses with low levels of applied mechanical energy.

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“…According to Wei et al [27], the addition of fly ash to cellulose fiber concrete modifies the initial pore structure and increases its durability against sulfate. Wdah et al [28] investigated the effects of w-d cycles on red mud waste solidified with desulfurization gypsum-fly ash. The effect of the cycle was investigated, and the practicality of employing resistivity response stress was confirmed.…”

Section: Introductionmentioning

confidence: 99%

Study on the Mechanical and Leaching Characteristics of Permeable Reactive Barrier Waste Solidified by Cement-Based Materials

et al. 2021

Self Cite

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The durability against wet-dry (w-d) cycles is an important parameter for the service life design of solidified permeable reactive barrier (PRB) waste. This study introduces the potential use of cement, fly ash, and carbide slag (CFC) for the stabilization/solidification (S/S) of PRB waste. In this study, solidified PRB waste was subjected to different w-d cycles ranging in times from 0 to 10. By analyzing the mass loss, the unconfined compressive strength (UCS), initial resistivity (IR), and the Mn2+ leaching concentration under different durability conditions, the results demonstrate that these variables increased and then tended to decrease with the number of w-d cycles. The UCS of contaminated soil is significantly correlated with IR. Moreover, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) analyses indicate that the hydration products calcium silicate hydrate (C-S-H) and ettringite (AFt) are the main reasons for the enhancement of the UCS. However, the increase in Mn2+ concentration leads to a decrease in hydration products and the compactness of solidified soil, which has negative effects for the UCS and the leaching ion concentration. In general, the durability exhibited by the PRB waste treated with S/S in this paper was satisfactory. This study can provide theoretical guidance for practical engineering applications.

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Study on stress-strain-resistivity and microscopic mechanism of red mud waste modified by desulphurization gypsum-fly ash under drying-wetting cycles

Cited by 26 publications

References 44 publications

A mechanical insight into the triggering mechanism of frequently occurred landslides along the contact between loess and red clay

A mechanical insight into the triggering mechanism of frequently occurred landslides along the contact between loess and red clay

Experimental Study on Immersion Effects of Pressure Water on the Tensile Characteristics of Sandstone Samples

Study on the Mechanical and Leaching Characteristics of Permeable Reactive Barrier Waste Solidified by Cement-Based Materials

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