Effects of Varying Coarse Aggregate Size on the Mechanical and Thermal Behavior of Concrete

Concrete is widely applied in various civil engineering structures under different environmental conditions and loading schemes. In this research, the compressive strength of various specimens with different aggregate sizes was experimentally investigated. The thermal resistance of the concrete blocks was investigated by studying the thermal insulation capacity and spalling behavior of the various specimens. The effects of the varying coarse aggregates on the fatigue crack growth were assessed by a three-point bending test under sinusoidal cyclic loading on the specimen using a crack opening displacement gauge. Concrete containing medium aggregates exhibited the highest compressive strength of 21.72 MPa, followed by larger aggregates with 16.95 MPa and small aggregates with 14.40 MPa. Fatigue crack propagated faster in the specimen with smaller aggregates and fractured at an early cycle of 31020 N than the medium (42320 N) and larger aggregates specimen (51002 N). The thermal insulation of the blocks also depended on the aggregate sizes used. Specimens with smaller aggregates were found to be poorer insulators than those with larger aggregates, due to their greater number of interfacial connection zones. It was also discovered that the spalled mass of concrete with smaller aggregates was higher (13.4%) than that with medium aggregates (10.4%) and with larger aggregates (7.3%).