Influence of surrounding rock temperature on mechanical property and pore structure of concrete for shotcrete use in a hot-dry environment of high-temperature geothermal tunnel

Pin, Liu; Cui, Shengai; Li, Zihao; Xu, Xuefeng; Guo, Chen

doi:10.1016/j.conbuildmat.2019.02.125

Cited by 87 publications

(39 citation statements)

References 27 publications

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“…It can be seen in Table 7 that all the values of Ds are between 2.5 and 3, and all the R 2 values are close to 1. Based on the fractal theory, the Ds values are meaningful between 2 and 3 24,36,38,59 , indicating that the pore structures of the concrete containing fly ash and/or silica fume have typical fractal characteristics. In addition, the relationships between Ds and the pore structure parameters (the average pore diameter and the most probable aperture of concrete) obtained by MIP are given in Fig.…”

Section: Mip Resultsmentioning

confidence: 99%

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Pore Structural and Fractal Analysis of the Influence of Fly Ash and Silica Fume on the Mechanical Property and Abrasion Resistance of Concrete

et al. 2021

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Dam concrete suffers from serious abrasion damages in southwestern China, the abrasion resistance of concrete is therefore one of the most important factors determining the reliability even the safety of the dams. In the present work, the effects of fly and/or silica fume on the mechanical properties, drying shrinkage, as well the cracking and abrasion resistance of concrete were investigated, then the pore structures of concrete added with fly ash and silica fume and the pore surface fractal dimensions (Ds) were determined by the mercury intrusion porosimetry (MIP) method and a fractal model, respectively. Finally, the relationships between the abrasion resistance of concrete and the porosity as well as the Ds were revealed and discussed. The results indicate that silica fume significantly increases the drying shrinkage especially at early age, while the incorporation of fly ash and silica fume together can decease the early plastic shrinkage-induced cracking risk and the final shrinkage to some degrees. Besides, the utilization of 5 wt% silica fume and 20 wt% fly ash together increases the abrasion resistance and mechanical property by about 4-9 % at various ages. In addition, the compressive strength and the abrasion resistance of concrete are linearly correlated with the concrete porosity and the Ds. Both the fly ash and silica fume could decrease the porosity of concrete and increase the Ds, therefore the concrete containing fly ash

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Section: Mip Resultsmentioning

confidence: 99%

“…was calculated using the fractal model based on the thermodynamic method deduced by Zhang et al 36,37 . This model has been widely used by others and proved to be an accurate one to characterize the Ds 24,31,36,38 .…”

Section: Fractal Models Of Pore Structurementioning

confidence: 99%

Pore Structural and Fractal Analysis of the Influence of Fly Ash and Silica Fume on the Mechanical Property and Abrasion Resistance of Concrete

et al. 2021

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“…Fractal models based on the mercury intrusion method are widely used to characterize the fractal features of cement-based materials, because the MIP technique provides the unique benefit of covering a relatively wide range of pore size [21][22][23]36 . These models include the space-filling model, Menger sponge model, and fractal model 21,23,24 .…”

Section: Methodology Of the Fractal Dimension Calculationmentioning

confidence: 99%

“…In addition, concrete is a typical porous material and possesses obvious fractal characteristics in pore shape, pore area and pore volume [20][21][22] . According to the fractal theory, the fractal dimension is an important parameter to characterize the complexity and inhomogeneity of the pores in concrete [21][22][23][24][25] . Some studies have addressed on the relationship between the mechanical property, durability, and fractal dimension of concrete.…”

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confidence: 99%

Effects of Fineness and Content of Phosphorus Slag on Cement Hydration, Permeability, Pore Structure and Fractal Dimension of Concrete

et al. 2021

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The utilization of phosphorus slag (PHS) to replace the fly ash in the construction of hydraulic projects has attracted a growing attention in China. In this study, the influence of PHS fineness and content on cement hydration, mechanical strength, permeability as well as the pore structure and fractal dimension (Ds) of concrete have been discussed. The results indicate that the PHS addition retards the cement hydration and hence decreases the hydration heat within 3 days. The incorporation of PHS with a Blaine specific surface area of 505 m 2 /kg (PHS) could participate in the early pozzolanic reaction and consequently offsets the retarding effect to some extent. The incorporation of 20-40 w% PHS declines the early strength of concrete, but this reduction effect on strength can be eliminated to some degrees by mechanically grinding the PHS. The compressive strengths of concrete added with PHS with a high fineness of 505 m 2 /kg

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“…Many researchers have studied the variation of macroscopic rock properties after high-temperature heat treatment and achieved some progress. Regarding the pore structure, various experimental techniques, including CT scanning electron microscope (CT-SEM) [15], mercury intrusion porosimetry (MIP) [16][17][18][19][20], micro-CT [21,22], field emission scanning electron microscopy (FE-SEM) [23,24], low-field nuclear magnetic resonance (NMR) [25], photoacoustic spectrometry (PAS) [26], ultrasonic velocity measurement (UVM) [27], etc., were used to study the high-temperature effects on the porosity, pore size, and pore morphology of various materials such as calcareous sediments [21], coal [15,25], concrete [16], shale [22][23][24], granite [28,29], sandstone [18,19,28], limestone [17,20], and carbonate [27]. Almost all of the above studies have shown that thermal damage and microcracks are induced by high temperature and the rock porosity and permeability gradually increase with temperature, while the pore fractal dimension decreases.…”

Section: Introductionmentioning

confidence: 99%

Mineral Composition, Pore Structure, and Mechanical Characteristics of Pyroxene Granite Exposed to Heat Treatments

et al. 2019

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In deep geoengineering, including geothermal development, deep mining, and nuclear waste geological disposal, high temperature significantly affects the mineral properties of rocks, thereby changing their porous and mechanical characteristics. This paper experimentally studied the changes in mineral composition, pore structure, and mechanical characteristics of pyroxene granite heated to high temperature (from 25 °C to 1200 °C). The results concluded that (1) the high-temperature effect can be roughly identified as three stages: 25–500 °C, 500–800 °C, 800–1200 °C. (2) Below 500 °C, the maximum diffracted intensities of the essential minerals are comparatively stable and the porous and mechanical characteristics of granite samples change slightly, mainly due to mineral dehydration and uncoordinated thermal expansion; additionally, the failure mechanism of granite is brittle. (3) In 500–800 °C, the diffraction angles of the minerals become wider, pyroxene and quartz undergo phase transitions, and the difference in thermal expansion among minerals reaches a peak; the rock porosity increases rapidly by 1.95 times, and the newly created pores caused by high heat treatment are mainly medium ones with radii between 1 μm and 10 μm; the P-wave velocity and the elastic modulus decrease by 62.5% and 34.6%, respectively, and the peak strain increases greatly by 105.7%, indicating the failure mode changes from brittle to quasi-brittle. (4) In 800–1200 °C, illite and quartz react chemically to produce mullite and the crystal state of the minerals deteriorate dramatically; the porous and mechanical parameters of granite samples all change significantly and the P-wave, the uniaxial compressive strength (UCS), and the elastic modulus decrease by 81.30%, 81.20%, and 92.52%, while the rock porosity and the shear-slip strain increase by 4.10 times and 11.37 times, respectively; the failure mechanism of granite samples transforms from quasi-brittle to plastic, which also was confirmed with scanning electron microscopy (SEM).

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Influence of surrounding rock temperature on mechanical property and pore structure of concrete for shotcrete use in a hot-dry environment of high-temperature geothermal tunnel

Cited by 87 publications

References 27 publications

Pore Structural and Fractal Analysis of the Influence of Fly Ash and Silica Fume on the Mechanical Property and Abrasion Resistance of Concrete

Pore Structural and Fractal Analysis of the Influence of Fly Ash and Silica Fume on the Mechanical Property and Abrasion Resistance of Concrete

Effects of Fineness and Content of Phosphorus Slag on Cement Hydration, Permeability, Pore Structure and Fractal Dimension of Concrete

Mineral Composition, Pore Structure, and Mechanical Characteristics of Pyroxene Granite Exposed to Heat Treatments

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