Abstract: In this study, the erosive effects and mechanisms of acidic water-chemical environments on road-use cement-based cured shield muck materials are investigated. First, indoor curing experiments are carried out on shield muck produced from the Chengnan river-crossing tunnel in Wuhu, China, using two curing agents, a new type of early-strengthening cement-based material (ESCA) and ordinary Portland cement 42.5 (P·O 42.5). Then, four aqueous solutions with pH values of 7, 5, 3, and 1 are prepared to soak the two cured muck specimens for a period of 45 days, and the specimens are comparatively tested for physical (mass and longitudinal wave velocity) and mechanical properties (unconfined compressive strength). Finally, scanning electron microscope and industrial computed tomography system are used to investigate the damage and deterioration mechanism of acid erosion on the microstructure of cured muck. The results show that: (1) The bearing structures of both ESCA-type and P·O 42.5-type cured specimens are deteriorated to different degrees after 45 days of acid leaching tests, and the strength of the two cured specimens decreases by 65.61% and 72.25% at pH=1 of the leaching solution, respectively. (2) The decrease of the pH value of the soaking solution increases the plastic deformation characteristics of the two types of cured muck specimens, and both types of cured muck specimens show a tendency to change from cleavage damage to shear damage at pH=3. (3) Compared with the P·O 42.5-type of cured muck specimens, the ESCA-type of cured muck specimens has less pore development after acid attack, and possesses a better ability to withstand acid corrosion.

Key words: cured shield muck, acid erosion, curing experiment, damage and degradation mechanism, computed tomography scanning