Multi-scale investigation of hybrid fiber-reinforced concrete for mitigating early-age shrinkage cracking in bridge deck pavements.
Early-age shrinkage cracking in concrete bridge deck pavements is a pervasive infrastructure challenge, with approximately 42% of decks developing cracks within the first week after construction. These defects raise long-term maintenance costs and weaken structural durability. This study assesses hybrid fiber-reinforced concrete, or HFRC, as an alternative to conventional reinforced concrete, using material property tests, two-dimensional digital image correlation (2D-DIC), and restrained shrinkage tests to compare crack resistance. Key findings show HFRC outperforms conventional concrete. Full-field 2D-DIC analysis revealed significant strain concentrations along the steel bars in traditional pavement layers. This suggests that the stiffness mismatch between the high-modulus steel reinforcement and the concrete matrix, coupled with internal restraint effects, may induce localized stress concentrations that guide the development of macro-cracks. Restrained shrinkage tests found traditional pavements formed more than 50% of their cracks within three days, while HFRC reduced total crack area by over 93% after 14 days, bringing it to less than 1/16 of conventional levels with notably smaller crack widths. This research identifies HFRC as a material-efficient alternative with potential durability benefits for effectively mitigating early-age cracking in bridge deck pavements. Its enhanced performance is attributed to the improved compatibility between material-scale deformation demands and system-level boundary restraints, which is interpreted to prevent restraint-induced stress concentrations from reaching the macroscopic cracking threshold.