Temperature-driven crack self-healing and performance recovery in cemented tailings materials

Cemented paste backfill (CPB) is an innovative cementitious construction material widely used to stabilize underground mine structures and minimize the mine's environmental impact. Understanding the factors that influence the self-healing efficiency of CPB is essential to optimize its design and improve its durability. In real-world applications, CPB structures are often exposed to varying curing temperatures, which can affect their self-healing ability. However, the specific impact of temperature on the self-healing capacity of CPB is not yet clearly established. This study experimentally investigates the effects of temperature (i.e., 2 degrees C, 20 degrees C, 35 degrees C, and 50 degrees C) on the selfhealing performance of CPB. The self-healing efficiency was evaluated through observations of crack closure, mechanical strength tests, hydraulic conductivity measurements, and assessments of physical properties (i.e., porosity and void ratio). The results demonstrate that temperature significantly influences CPB's self-healing performance. Elevated temperatures (35 degrees C and 50 degrees C) enhance the self-healing process within the CPB matrix compared to room temperature (20 degrees C), primarily due to accelerated binder hydration. The pre-cracked CPB specimens can restore their strength and achieve up to approximately 31 % higher strength than uncracked specimens after 28 days of self-healing. However, the pre-cracked specimens cured at low temperature (i.e., 2 degrees C) exhibit low self-healing capacity, particularly at early ages. The low curing temperature significantly delays the onset of the self-healing process in CPB material. Moreover, analytical techniques reveal that an amount of healing products, mainly consisting of C-S-H, Ca(OH)2, and CaCO3, contribute to this promising self-healing performance. The findings from this paper have important practical implications for the design, mechanical stability, and durability of CPB structures, providing valuable insights for engineering practices.