Performance change of shaft lining concrete under simulated coastal ultra-deep mine environments

This paper reports research on the performance change of fibre-reinforced high-performance concrete (FRHPC) and fibre-reinforced reactive powder concrete (FRRPC) subjected to simulated coastal ultradeep mine environments. The phase content, morphology, and pore structure characteristics of the hardened pastes were investigated by means of a series of quantitative methods, and the degree of hydration (DoH) and degree of pozzolanic reaction (DoPR) were calculated. The experimental results indicate that there is a great difference in DoH and DoPR between high-performance hardened paste (HPHP) and reactive powder hardened paste (RPHP) at 28 days and that they show consistent behaviour after immersion. The failure of high-performance concrete in coastal ultra-deep mines may be caused by the crystallization pressure of Friedel's salt. Moreover, a high underground temperature can be slightly beneficial for the durability of the concrete. The conclusions obtained provide theoretical support for the construction of ultra-deep coastal mines. (C) 2019 Elsevier Ltd. All rights reserved.