This study selects polypropylene fibers (PP) and polyacrylonitrile fibers (PAN) as reinforcing contents of high-strength wear-resistant fly ash concrete (HF concrete) to improve its brittle damage characteristics. Combining digital image correlation technology (DIC) and ultrasonic detection (UT)
we conduct experimental tests and examine the stress-strain characteristic parameters of this fiber-reinforced HF concrete under the condition of compression damage. The results show its damage and failure process can be divided into five stages-elasticity
plasticity
sudden damage
accelerated damage
and residual damage. PP inhibits the initiation of microcracks in elastoplastic stage
and PAN inhibits the propagation of microcracks in abrupt damage stage. With a PP content of 0.6 kg/m3 and PAN of 0.6 kg/m3
the concrete enjoys the best hybrid effect and a peak stress increase of 8.35% or 4.47% in comparison with that of the single PP or PAN respectively
and it manifests an increase of 23.74% or 9.87% respectively in its compressive toughness index. Finally
a stress-strain full curve model is developed for such fiber-reinforced HF concrete based on the CEB-FIP model and Guo Zhenhai model
and it is optimized using an improved differential evolution algorithm. It gives optimized stress-strain full curves in good agreement with the experimental curves. Our findings help engineering application of fiber-reinforced HF concrete and lay a basis for follow-up research.