Exploratory study on improving bond strength of shotcrete in hot and dry environments of high geothermal tunnels

Cui, Shengai; Xu, De-Li; Liu, Pin; Ye, Yuezhong

doi:10.1007/s12205-016-0901-y

Cited by 20 publications

(14 citation statements)

References 5 publications

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“…Francesco et al [114] proposed that the performance of shotcrete could be optimized by changing the density of the material to reduce the pore pressure and the gravitational potential energy of shotcrete. [108]. BP: non-fiber material; SF-HE: 1% hook-end steel fiber; SF-W: 1% corrugated steel fiber; BF: 0.1% basalt fiber; SF-HE+Si: 1% steel fiber and 5% silica fume.…”

Section: Solution Dehumidification and Coolingmentioning

confidence: 99%

“…Francesco et al [114] proposed that the performance of shotcrete could be optimized by changing the density of the material to reduce the pore pressure and the gravitational potential energy of shotcrete. Cui et al [107,108] studied the performance changes of shotcrete mixed with hookend steel fiber (SF-HE), wave-shaped steel fiber (SF-W), and basalt fiber (BF) at 100 °C, and found that the total porosity and harmful porosity of shotcrete decreased significantly after adding fiber, and the optimization effect of steel fiber on pore structure was better than that of basalt fiber. However, the porosity of shotcrete increased after the steel fiber and silica fume were mixed, which indicated that the pozzolanic activity of silica fume fails under high temperature, as shown in Figure 20.…”

Section: Solution Dehumidification and Coolingmentioning

confidence: 99%

“…BP: non-fiber material; SF-HE: 1% hook-end steel fiber; SF-W: 1% corrugated steel fiber; BF: 0.1% basalt fiber; SF-HE+Si: 1% steel fiber and 5% silica fume. [108]. BP: non-fiber material; SF-HE: 1% hook-end steel fiber; SF-W: 1% corrugated steel fiber; BF: 0.1% basalt fiber; SF-HE+Si: 1% steel fiber and 5% silica fume.…”

Section: Solution Dehumidification and Coolingmentioning

confidence: 99%

“…Figure 20. Porosity of different pores under different conditions[108]. BP: non-fiber material; SF-HE: 1% hook-end steel fiber; SF-W: 1% corrugated steel fiber; BF: 0.1% basalt fiber; SF-HE+Si: 1% steel fiber and 5% silica fume.…”

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confidence: 99%

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Mechanical Properties and Microstructure of Shotcrete under High Temperature

Liu

Zhao

Zhang³

et al. 2021

Applied Sciences

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High temperature is recognized as one of the extreme environments in the application of shotcrete which significantly deteriorate the performance of shotcrete. This paper reviews the mechanical properties and microstructure of shotcrete under high temperature. First of all, this paper reviews the cause of formation of high ground temperature. Based on these causes, the author establishes a heat transfer model with a spiral shape by introducing a multidimensional morphological formula into the heat conduction process. Then, the paper reviews the influence of high temperature on the mechanical and micro properties of shotcrete, the cooling technology under high temperature, and the optimization research technology of shotcrete. The author discusses the influence of high temperature on the thermal parameters and the deformation of shotcrete from the perspective of thermodynamics. Multiple studies have shown that the irregular movement and disorderly overlapping of molecules in the shotcrete caused by the high temperature environment result in the premature termination of the hydration reaction of cement in shotcrete. Finally, the author suggests the challenges of high-temperature shotcrete in term of the process structure, performance optimization, and application in special engineering fields. The research in this paper intends to give guidance to those conducting shotcrete research under high temperature, and to promote the further development of shotcrete technology.

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“…Francesco et al [114] proposed that the performance of shotcrete could be optimized by changing the density of the material to reduce the pore pressure and the gravitational potential energy of shotcrete. [108]. BP: non-fiber material; SF-HE: 1% hook-end steel fiber; SF-W: 1% corrugated steel fiber; BF: 0.1% basalt fiber; SF-HE+Si: 1% steel fiber and 5% silica fume.…”

Section: Solution Dehumidification and Coolingmentioning

confidence: 99%

“…Francesco et al [114] proposed that the performance of shotcrete could be optimized by changing the density of the material to reduce the pore pressure and the gravitational potential energy of shotcrete. Cui et al [107,108] studied the performance changes of shotcrete mixed with hookend steel fiber (SF-HE), wave-shaped steel fiber (SF-W), and basalt fiber (BF) at 100 °C, and found that the total porosity and harmful porosity of shotcrete decreased significantly after adding fiber, and the optimization effect of steel fiber on pore structure was better than that of basalt fiber. However, the porosity of shotcrete increased after the steel fiber and silica fume were mixed, which indicated that the pozzolanic activity of silica fume fails under high temperature, as shown in Figure 20.…”

Section: Solution Dehumidification and Coolingmentioning

confidence: 99%

Section: Solution Dehumidification and Coolingmentioning

confidence: 99%

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confidence: 99%

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Mechanical Properties and Microstructure of Shotcrete under High Temperature

Liu

Zhao

Zhang³

et al. 2021

Applied Sciences

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“…In addition to the problem of high temperature, the influence of relative humidity (RH) in high-geothermal tunnels on grouting materials should not be underestimated. Some studies have suggested that it is easy to cause decreases in compressive strength and bond strength in grouting material in a hot-dry environment [22,23]. There exists a significant combined effect of temperature and relative humidity.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Characteristics of Cement-Based Grouting Material in High-Geothermal Tunnel

Wang

Jiang

et al. 2020

Materials

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The cement-based grouting materials used for practical purposes in high-geothermal tunnels are inevitably affected by humidity and high temperature, leading to the deterioration of mechanical properties. Based on the characteristics of changing high temperatures and two typical conditions of hot-humid and hot-dry environments in high-geothermal tunnels, many mechanical strength tests were carried out on the grouting material cured under different environmental conditions. The study results indicated that high temperature and low relative humidity were unfavorable to the development of mechanical characteristics of grouting material, but the coupling effect of two factors could improve the strength at early ages and reduce the degradation of long-term strength. As the curing temperature exceeded 56.3 °C, the humidity effect on strength played a more important role in recovering the strength of grouting material damaged by high temperature. Temperature had more significant impact on the relative peak stress while the relative humidity had greater influence on the relative peak strain. A calculation compressive constitutive model was prospered, which considering both temperature and relative humidity. The study results may provide much valuable experimental data and theoretical supporting for the design of compression constitutive of cement-based grouting material in high-geothermal tunnel.

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Experimental evaluation on mechanical and thermal insulation properties of shotcrete under constant‐variable temperature

Chen

Zhao

Meng

et al. 2022

Structural Concrete

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One of the commonly used stabilization systems for rock tunnel is shotcrete. However, the hydration of shotcrete is usually accompanied by the development of internal defects and micro damage under high temperature. Additionally, in the actual high‐temperature engineering, the temperature of the rock tunnel exhibits irregular changes. Therefore, in this study, the curing conditions of constant temperature (23°C, 40°C, 60°C, 80°C) and variable temperature (23–40–60–80°C, 80–60–40–23°C) are set, respectively. The mechanical properties and structural properties of polyurethane shotcrete and ordinary Portland shotcrete are introduced. It is determined that the limit temperature for inhibiting the development of sprayed concrete's compressive and splitting strength is between 60°C and 80°C, and the limit temperature for inhibiting the development of bond strength is about 40°C. Meanwhile, the influence of high temperature on the thermal insulation performance of shotcrete is considered. The results that the self‐foaming performance of polymer(polyurethane) reduces the thermal conductivity of shotcrete. Based on this phenomenon, the heat transfer model of shotcrete at room and high temperature is established to clarify the heat transfer process of shotcrete. Results will provide theoretical basis for further research of durability and heat insulation performance of protective spraying material for tunnel under high temperature.

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Exploratory study on improving bond strength of shotcrete in hot and dry environments of high geothermal tunnels

Cited by 20 publications

References 5 publications

Mechanical Properties and Microstructure of Shotcrete under High Temperature

Mechanical Properties and Microstructure of Shotcrete under High Temperature

Mechanical Characteristics of Cement-Based Grouting Material in High-Geothermal Tunnel

Experimental evaluation on mechanical and thermal insulation properties of shotcrete under constant‐variable temperature

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