• Composite specimens exhibit strength enhancements exceeding 5 MPa under cyclic loading, while pure materials show a decrease of approximately 1 MPa.
• Peak strength of coal-concrete composites decreases with increasing coal height, from 30 MPa at CR0.5 to 20 MPa at CR3.0.
• Acoustic emission monitoring reveals that composite specimens are more prone to early damage accumulation, as indicated by dynamic elastic strain energy index and Felicity ratio.
• A modified twin-shear unified strength theory incorporating interfacial effects accurately predicts the internal strength distribution and failure characteristics of composite structures.