Resistance to Sulfate Attack and Chemo-Damage-Transport Model of Sulfate Ions for Tunnel Lining Concrete under the Action of Loading and Flowing Groundwater

Abstract

In this study, resistance to sulfate attack and a chemo-damage-transport model of sulfate ions for tunnel lining concrete under the action of loading and flowing groundwater are investigated. The results show that in the initial stage of erosion, the relative dynamic elastic modulus of tunnel lining concrete and the sulfate ion concentration increase gradually. However, in the subsequent stage of erosion, the relative dynamic elastic modulus of tunnel lining concrete decreases gradually, and the increase in sulfate ion concentration accelerates. The defects of the tunnel lining concrete in the tensile zone and compressive zone can be expanded and closed, respectively, under the action of the loading. Meanwhile, the tunnel lining concrete can be corroded under the action of flowing groundwater. Therefore, the sulfate ion concentration in the tensile zone is the highest under the action of loading and flowing groundwater. The second highest value is obtained under the action of only flowing groundwater, which is followed by the action of static groundwater. The sulfate ion concentration in the pressure zone is the lowest under the action of loading and flowing groundwater. The chemical reaction in the process of sulfate erosion, damage of tunnel lining concrete by crystallization pressure and loading, and influence of flowing groundwater dissolution on calcium leaching are considered in combination, and a weight coefficient is introduced to characterize the influence of pore structure on the crystallization pressure. Finally, a chemo-damage-transport model of sulfate ions is established and its rationality is verified.

Corrosion damage and life prediction of concrete structure in the coking ammonium sulfate workshop of iron and steel industry

“…It might be well known that gypsum reacted with aluminate phase to form ettringite in concrete under sulfate attack 30 – 32 , while ettringite could not be observed in concrete under the action of CO 2 and SO 2 . This was because CO 2 and SO 2 were dissolved in the pore solution and ionized into H + , which reacted with alkaline hydration products.…”

A Comparative Study on the Mechanical Properties and Microstructure of Cement-Based Materials by Direct Electric Curing and Steam Curing

“…This indicates that the pore size inside the EC specimen was smaller than that of the SC specimen for the same porosity. The pores in the cement paste can be divided into four types according to the pore diameters [ 37 , 38 ]: large pores (d ≥ 1000 nm), capillary pores (1000 nm ≤ d < 100 nm), transition pores (10 nm ≤ d < 100 nm), and gel pores (d < 10 nm). Among them, pores greater than 100 nm in diameter are harmful pores, leading to a decrease in mortar strength [ 39 ].…”

Lowari Tunnel Water Quality Evaluation: Implications for Tunnel Support, Potable Water Supply, and Irrigation in Northwestern Himalayas, Pakistan

“…Concrete lining is carried out for strengthening tunnel walls and tunnel crowns to counter the water pressure and prevent water seepage and surface settlement in a tunnel [22]. Water in tunnels with an excessive amount of sulfate alters the composition of cement, weakens the bond between the aggregate and cement paste, and results in cracks [23,24]. In Switzerland, high chloride levels in the water continue to cause concrete to corrode [25].…”