Application of microwave heating technique is highly promising in assisting rocks breakage and recycling coarse aggregate in waste concrete. This work focus on crack propagation behavior and hence damage of hard rocks subjected to microwave irradiation. Heating effects of basalt and its main mineral components are investigated experimentally using a multimode industrial microwave system. Crack characterization of basalt after irradiating are observed using scanning electron micrograph (SEM). A theoretical model based on heating effects of mineral components is established to deduce crack propagation within basalt under microwave irradiation. Temperature rise of magnetite is drastic while that of other mineral components are tardy. Fracture of basalt is induced by predominant radial crack propagation around the rapidly heated mineral particle. Cracks can be divided into short cracks and long cracks by a characteristic length during extending. Microwave energy required for extension of cracks with characteristic length is minimum. Propagation of initial short cracks results in greater extent of damage evolution instantaneously. Moreover, damage increases with the mineral content of magnetite and decreases with crack density.

微波加热技术在辅助碎石和回收废弃混凝土中的粗骨料方面具有广阔的应用前景。这项工作的重点是裂纹扩展行为以及微波辐射对硬岩的破坏。使用多模工业微波系统对玄武岩及其主要矿物成分的加热效应进行了实验研究。使用扫描电子显微照片 (SEM) 观察辐照后玄武岩的裂纹特征。建立了基于矿物成分热效应的理论模型，推断微波辐射下玄武岩内的裂纹扩展。磁铁矿温升剧烈，其他矿物成分温升缓慢。玄武岩的断裂是由快速加热的矿物颗粒周围主要的径向裂纹扩展引起的。裂纹按延伸过程中的特征长度可分为短裂纹和长裂纹。扩展具有特征长度的裂纹所需的微波能量最小。初始短裂纹的传播会导致更大程度的损伤演化瞬间。此外，损伤随着磁铁矿矿物含量的增加而增加，随着裂纹密度的增加而减小。