Static and Dynamic Performance of Steel-Fiber-Reinforced Polymer-Modified Concrete: Strength, Toughness and Crack Resistance.

Conventional concrete pavement materials remain limited in flexural strength, deformability, post-cracking load-carrying capacity, and impact resistance. To address these deficiencies, this study investigates the effects of polymer modification and ultrashort ultrafine steel fiber reinforcement on the static and dynamic mechanical responses and crack evolution of concrete. The results show that polymer modification enhances deformability, while steel fiber incorporation further increases flexural strength and ultimate flexural strain and improves post-cracking load-carrying capacity. Under repeated impact loading, the nominal impact energy input required for initial cracking and final failure increased; in particular, polymer-modified concrete containing 5% steel fibers showed increases of 938.76% in ultimate flexural strain and 8682.63% in the number of impacts to failure relative to ordinary concrete. The matrix and interfacial morphologies observed by scanning electron microscopy (SEM) were consistent with the macroscopic mechanical responses, supporting the interpretation that polymer modification improves matrix and interfacial integrity, while steel fibers contribute to post-cracking load transfer through crack bridging. Overall, the material exhibited high deformability and damage tolerance, indicating its potential for specialized pavement applications.