Sustainable Nonstructural Concrete Using Field-Sourced Recycled Concrete Aggregate from Bridge Demolition: Mechanical Behavior and Performance Boundaries

The use of recycled concrete aggregate (RCA) derived from demolished bridges offers a practical approach for reducing reliance on virgin aggregates in transportation construction. The goal of this study is to investigate the mechanical performance of concrete incorporating coarse RCA obtained from bridge demolition projects in eastern North Carolina and to evaluate its suitability for local nonstructural concrete applications. Aggregate characterization, fresh concrete evaluation, compressive strength testing at 7, 28, and 90 days, and full stress–strain analysis were conducted in accordance with ASTM standards. Three replicate cylinders (4 in. × 8 in./102 mm × 203 mm) were tested per mixture and age. Results indicate that increasing RCA replacement primarily affected density and early-age strength, with a limited influence on long-term compressive strength. Although mixtures with high RCA contents exhibited slightly reduced 7-day strength and lower unit weight, all mixtures exceeded Class B strength requirements specified by the North Carolina Department of Transportation at later ages. Stress–strain analysis showed stable post-peak behavior and no systematic increase in brittleness with RCA content. Mixtures incorporating locally available electric arc furnace steel slag demonstrated additional strength enhancement. These results present systematic relationships among RCA replacement levels, strength development, and deformation behavior under practical processing conditions. The study establishes experimentally grounded insight into the mechanical behavior of transportation-derived recycled aggregates and defines practical performance boundaries for their use in nonstructural transportation concrete, especially in eastern North Carolina infrastructure rehabilitation projects.