Durability of shotcrete for underground support– Review and update

Galán, Isabel Moratilla; Baldermann, Andre; Kusterle, Wolfgang; Dietzel, Martin; Mittermayr, Florian

doi:10.1016/j.conbuildmat.2018.12.151

Cited by 143 publications

(50 citation statements)

References 188 publications

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“…Since steel fibers "seal" the concrete cover [7,17], they might also indirectly inhibit the corrosion of the primary reinforcement in reinforced concrete structures, thus improving the rebar's durability. In highly developed countries, most construction works with shotcrete use concrete with dispersed reinforcement, usually in the form of steel fibers (so-called SFRC), due to its good parameters and relatively low price [4,5,8,9]. However, in many other countries, Poland included, this composite is not particularly popular, which is difficult to comprehend.…”

Section: Parameter Steel Fibers Polymer Fibers Basalt Fibers Glass Fmentioning

confidence: 99%

“…Sprayed concrete (shotcrete) [1][2][3] is frequently used as a filling material, a protective and finishing material for repairs of civil engineering structures and industrial structures (mainly in concrete cover and to protect steel against corrosion), or in the reconstruction of damaged historic buildings, particularly in the case of limited or difficult access [3][4][5][6][7]. Repairs with sprayed concrete can be performed by casting the concrete mix onto thin-wired steel meshes placed on the surfaces of the repaired elements (this usually requires casting two layers of shotcrete), or by using fiber-reinforced concrete (FRC), i.e., concrete with dispersed reinforcement in the form of various fibers, which eliminates the need for meshes [2,3,8,9].…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical Diagnostics of Sprayed Fiber-Reinforced Concrete Corrosion

Raczkiewicz

Kossakowski

2019

Applied Sciences

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Sprayed fiber-reinforced concrete is used in construction for the execution and repair of reinforced concrete elements. It is believed that the addition of steel fibers is most effective, due to their parameters and low costs. Some researchers, however, suggest that the addition of steel fibers can contribute to the initiation of corrosion of the main reinforcement. In consideration of the differences of opinion on the corrosion resistance of sprayed fiber-reinforced concrete, it has become necessary to analyze this issue. The article presents comparative studies of corrosion assessments of the main reinforcement in specimens made of ordinary concrete and concrete with steel fibers. The tests were performed using a semi non-destructive galvanostatic pulse method, which allows location of the areas of corrosion and estimation of the reinforcement corrosion activity. In order to initiate the corrosion processes the specimens were subjected to freezing cycles in NaCl solution. In addition, the shrinkage and compressive strength of specimens were measured, and the observation of specimen structure under a scanning microscope was performed. It was found that galvanostatic pulse method allowed estimation of the reinforcement corrosion progress. The corrosion of the main reinforcement in steel fiber reinforced concrete specimens was less advanced than in the specimens without fibers.

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Section: Parameter Steel Fibers Polymer Fibers Basalt Fibers Glass Fmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electrochemical Diagnostics of Sprayed Fiber-Reinforced Concrete Corrosion

Raczkiewicz

Kossakowski

2019

Applied Sciences

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“…Studies have shown that the sawtooth depth "h" has a greater impact on the interfacial (1) Spray watering (2) Insulate high-temperature surrounding rock and add 0.03% high efficiency airentraining agent to spray concrete (3) For the digging puddles in the high-water temperature section, the water pump is used to discharge the hot water (4) Transporting ice cubes to the excavation surface cohesion, and the rough rock surface affects the mechanical behaviour of the concrete (Figure 15). However, there is no quantitative discussion of the effect of roughness on the interface bearing capacity [71,74,75]. Roughness, as an indicator of rock mechanics, plays an important role in studying the mechanical properties of rock contact surface, and it mainly controls the degree of undulation of the contact surface, which in turn affects the shear bite force and frictional resistance [76][77][78][79][80][81].…”

Section: Other Methodsmentioning

confidence: 99%

Influence of Ground Temperature on Shotcrete-to-Rock Adhesion in Tunnels

Duan

Zhang

Lai

2019

Advances in Materials Science and Engineering

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Long and deep tunnels are increasingly designed and built worldwide, often in severe geothermal environments characterized by high temperature in the rocks. is issue cannot be ignored because high temperature definitely affects the strength of the adhesion between the concrete and the surrounding rocks, whatever the lining cast in place, segmental or sprayed using shotcrete. e causes of geothermal heat and the effect of the temperature on tunnel linings during and after their construction are recalled and discussed in this paper. Both temperature and humidity are shown to be the most relevant factors affecting adhesion strength, whose loss is related to the microdamage in the shotcrete layers closest to the rock. Possible ways to improve adhesion strength and to minimize the high-temperature detrimental effect are also presented and discussed.

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“…Moreover, the simultaneous formation of C-A-S-H in equilibrium with brucite (MgðOH 2 Þ) and magnesium silicate hydrate (M-S-H) phases can further weaken the concrete and bentonite barriers matrices (i.e. increase in secondary porosity), which can facilitate various other forms of physical and chemical attack, such as the alkali-aggregate reaction, recrystallization of C-A-S-H induced by Ca 2þ leaching, carbonation, formation of salt crusts, sulphate attack, corrosion of steel containers, and ion exchange [7,[75][76][77].…”

Section: Nuclear Waste Disposal Sitesmentioning

confidence: 99%

“…Importance of calcium-aluminium-silicatehydrate phases Aluminium-substituted calcium-silicate-hydrates (C-A-S-H) are of great technological importance, because they represent the main hydration product in ordinary Portland cement (OPC) and thus significantly contribute to the physicochemical characteristics, mechanical properties, and durability of hardened cementitious materials, such as concrete and shotcrete [1][2][3][4][5][6][7]. Apart from being the most important construction material of our time, concrete is nowadays applied in special wastewater treatment technologies and in the remediation of (sub)soil structures that are contaminated with hazardous components, like toxic heavy metal ions [4,[8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Removal of heavy metals (Co, Cr, and Zn) during calcium–aluminium–silicate–hydrate and trioctahedral smectite formation

et al. 2019

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Hydrated aluminosilicates were synthesized with and without aqueous heavy metals (Me), such as cobalt (Co), chromium (Cr), and zinc (Zn), by a sol-gel process at different initial molar ratios of Ca/(Si ? Al) (0.6-1.6) and Me/Si (0.0-2.0), and constant Al/Si ratio (0.05) using equilibrium-approaching experiments. The chemical composition of the reactive solutions during aluminosilicate precipitation and maturation was monitored by ICP-OES. The mineralogy, nanostructure, and chemical composition of the precipitates were studied by XRD and high-resolution TEM. At Me/Si ratios B 0.2, calcium-aluminium-silicate-hydrates (C-A-S-H) with a defect 14 Å tobermorite-like structure formed, whereas at a Me/Si ratio of 2.0, either trioctahedral Co-and Zn-smectite or amorphous Cr gels precipitated, independent of the initial Ca/(Si ? Al) ratio used for gel synthesis. The immobilization capacities for Co 2þ , Cr 3þ , and Zn 2þ by C-A-S-H, Cr gel, and trioctahedral smectite are 3-40 mg/g, 30-152 mg/g, and 122-141 mg/g, respectively. The immobilization mechanism of heavy metals is based on a combination of isomorphous substitution, interlayer cation exchange, surface (ad)sorption, and surface precipitation. In engineered systems, such as underground concrete structures and nuclear waste disposal sites, hydrated aluminosilicates should exhibit a high detoxication potential for aqueous heavy metals.

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Durability of shotcrete for underground support– Review and update

Cited by 143 publications

References 188 publications

Electrochemical Diagnostics of Sprayed Fiber-Reinforced Concrete Corrosion

Electrochemical Diagnostics of Sprayed Fiber-Reinforced Concrete Corrosion

Influence of Ground Temperature on Shotcrete-to-Rock Adhesion in Tunnels

Removal of heavy metals (Co, Cr, and Zn) during calcium–aluminium–silicate–hydrate and trioctahedral smectite formation

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