Influence of Sulfate on Mechanical Properties of Shaft Wall Concrete in Ultra-Deep Wells and Its Degradation Mechanism

Abstract

Abstract: In view of the severe service conditions of high temperature, high stress, high permeability and strong corrosion faced by concrete materials in deep underground engineering, this paper selects C70 imitation steel fiber reinforced concrete (C70-ISFRC) and high performance ultra-deep well wall concrete (HUC) as research objects to study the mechanical properties, failure forms and bursting liability of the two kinds of concrete under sulfate dry-wet cycle conditions. The degradation mechanism of C70-ISFRC and HUC were analyzed by SEM and EDS. The results show that with the progresses of sulfate dry-wet cycle, the mechanical properties of the two kinds of concrete increase first and then decrease, but the performance of HUC is more excellent than C70-ISFRC. In addition, the splitting tensile strength is more sensitive than the compressive strength under the condition of sulfate dry-wet cycle. The toughness of the two kinds of concrete become worse, but the copper plated steel fibers in HUC have better tensile properties than polypropylene imitation steel fibers, which make the HUC board “broken but complete”. In addition, the bursting liability of both kinds of concrete become stronger, but the bursting liability of HUC is weaker than C70-ISFRC. Under the condition of sulfate dry-wet cycle, the corrosion type of HUC is gypsum corrosion and the corrosion type of C70-ISFRC is AFt corrosion, which indicates that the expansion stress in concrete leads to the cracking of internal structure of concrete.

Key words: high performance ultra-deep well wall concrete, C70 imitation steel fiber reinforced concrete, sulfate environment, impact tendency, four point bending, crystallization damage

CLC Number:

TU528

ZHAO Xiaohong, SHEN Yu, LIU Juanhong, GUO Zidong. Influence of Sulfate on Mechanical Properties of Shaft Wall Concrete in Ultra-Deep Wells and Its Degradation Mechanism[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2021, 40(9): 2939-2947.

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