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BULLETIN OF THE CHINESE CERAMIC SOCIETY ›› 2024, Vol. 43 ›› Issue (7): 2415-2426.

Special Issue: 水泥混凝土

• Cement and Concrete • Previous Articles     Next Articles

Influence of Carbonate Environment on Performance and Microscopic Characteristics of Tunnel Concrete

LI Kang1,2, GAO Meng3, ZOU Min4, LIU Juanhong4, XIE Yongjiang2   

  1. 1. Postgraduate Department, China Academy of Railway Sciences, Beijing 100081, China;
    2. State Key Laboratory for Track System of High-Speed Railway, China Academy of Railway Sciences Corporation Limited, Beijing 100081, China;
    3. School of Civil Engineering, Henan University of Technology, Zhengzhou 450001, China;
    4. College of Civil and Resources Engineering, University of Science and Technology Beijing, Beijing 100083, China
  • Received:2023-12-15 Revised:2024-01-08 Online:2024-07-15 Published:2024-07-24

Abstract: To investigate the erosion and deterioration of railway tunnel lining concrete in karstic areas, this study focuses on ordinary Portland cement concrete and calcium sulfoaluminate cement concrete, as well as shotcrete. An environment of accelerated corrosion through carbonate exposure was simulated. The impact of carbonate environment on the macroscopic properties and microscopic characteristics of different types of tunnel concrete was studied using macroscopic performance testing and microscopic testing methods such as X-ray diffraction analysis, Fourier-transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. The mass, relative dynamic modulus of elasticity and compressive strength of concrete show an initial increase followed by a subsequent decrease with the increase of immersion duration. The decline starts after 180 d of immersion, in which the compressive strength of calcium sulfoaluminate cement concrete is lower than the initial value after immersing for 360 d. Microstructural analysis of the concrete reveals that after 360 d of erosion, the crystals and gels in the original hydration products of the samples sharply decrease, giving rise to a significant amount of calcium carbonate. In the samples of calcium sulfoaluminate cement concrete, [Si(OH)6]2- octahedral groups are detected, confirming the formation of thaumasite. The calcium sufoaluminate cement-based concrete with ettringite as the main hydration product is more significantly affected by carbonate erosion.

Key words: tunnel concrete, carbonate solution, thaumasite, compressive strength, hydration product, microscopic structure

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