Dynamic mechanical behaviour of PVA micro-fibre rubber concrete under multi-factor effects

The dynamic mechanical properties of rubber concrete reinforced with polyvinyl alcohol (PVA) micro-fibres under the combined effects of high temperature, corrosive solutions and impact loading were investigated using split Hopkinson pressure bar tests and scanning electron microscopy (SEM) analysis. The results show that the dynamic compressive strength and elastic modulus were strongly affected by the impact pressure, temperature and solution exposure. Under severe degradation, the apparent strength increase with an increase in impact pressure was amplified by low baseline strength and lateral inertial confinement, whereas intrinsic material deterioration was most pronounced in mixed salt environments, with a 66% strength reduction at 300°C and an impact pressure 0.3 MPa relative to untreated specimens. A higher impact pressure increased reflected, absorbed and transmitted energies, while the transmitted energy ratio remained comparatively stable. Fragment size decreased with increasing impact pressure, reaching a minimum average size of 27 mm for specimens treated with sodium chloride at 300°C and 0.5 MPa. SEM observations indicated that, with immersion in sodium sulfate solution, gypsum crystals formed can partly hinder crack propagation, whereas this beneficial effect was weakened under mixed salt attack (sodium sulfate + sodium chloride). These findings clarify the distinction between apparent strain rate related enhancement and intrinsic material degradation, providing guidance for the design of protective concrete structures under complex service conditions.