Abstract
The presence of cracks within the cemented paste backfill (CPB) matrix can stem from multiple factors like excessive pressures from CPB overburden, stresses induced by the closure of adjacent rock walls, rockbursts, and shrinkage. These cracks significantly compromise structural integrity, mechanical strength, and increase permeability, impacting safety, durability, and environmental performance. While the self-healing technique has been extensively explored in conventional cementitious materials like concrete and mortar to repair cracks and reduce maintenance costs, limited studies have delved into CPB’s self-healing capability. This study aims to explore the self-healing (autogenous healing) behavior within CPB materials, evaluating the healing efficiency in restoring mechanical strength and hydraulic conductivity. CPB samples were pre-cracked with different levels of pre-cracking to initiate different crack widths after initial curing. Subsequently, these samples underwent self-healing periods ranging from 7 to 90 days. The results revealed a significant self-healing capacity within CPB materials. After 7 days of self-healing, pre-cracked specimens restored mechanical and permeation properties to levels comparable to uncracked control specimens without external intervention. Moreover, CPB specimens with high pre-cracking levels even exhibited up to a 22% increase in mechanical strength compared to control specimens after a 90-day self-healing period. This suggests that cracks within the CPB matrix can enhance hydration reactions, thereby favoring improved self-healing performance. These findings provide valuable insights into CPB’s self-healing behaviour, holding significant implications for engineering CPB structures, evaluating their safety, durability, and serviceability and offering sustainable solutions for the mining industry.