Strain rate effect on the axial compressive properties of basalt fiber-reinforced ambient-cured lightweight expanded polystyrene geopolymer concrete

To investigate the strain rate effect of basalt fiber (BF)-reinforced ambient-cured lightweight expanded polystyrene (EPS) geopolymer concrete (LEGC), this study conducted uniaxial compression tests on BF-reinforced LEGC with different EPS doping and different strain rates. The test results showed that the final damage mode of the specimen was localized shear damage with increasing strain rate and EPS volume content. The damage pattern of BF-reinforced LEGC under the dynamic strain rate exhibited excellent crack resistance and energy dissipation properties compared to other lightweight concretes. Meanwhile, energy dispersive spectroscopy (EDS) analysis revealed that the Ca/Si ratio was larger in specimens with a higher strain rate and lower EPS volume content. In addition, it also revealed that the modulus of elasticity and compressive strength of the specimens were significantly enhanced with increasing strain rate. The more EPS doped, the more significant the enhancement effect, which showed a significant strain rate sensitivity effect. Subsequently, empirical equations for the variation in the dynamic increase factor (DIF) with strain rate were further developed. Finally, a model of the strength of the effect of the coupling of EPS particles and strain rate on the compressive strength of the specimen was developed based on the theory of fracture mechanics, which considered the effect of the thermal activation mechanism and macroscopic viscous mechanism. The comparison indicated that the strength model was consistent with the variation in the test data, which offered certain theoretical basis for the strain rate effect on BF-reinforced LEGCs.