Performance assessment of recycled concrete aggregate from a 60-year-old stadium: A comparative study with laboratory-produced aggregate

This study assesses the feasibility of using recycled concrete aggregates (RCA) from a 60-year-old demolished soccer stadium in Brazil (RCA-old) in comparison with RCA produced from one-year-old laboratory specimens (RCA-new) and high-quality granite aggregate. Both RCA types were processed to a maximum size of 12.5 mm and characterized for particle size distribution, shape, water absorption, density, micro-Deval abrasion resistance, and residual adhered mortar content. Concrete mixes with comparable workability – one with 100% granite (control) and two with 50% of RCA – were evaluated for compressive strength at 7, 14 and 28 days, water absorption, and resistance to sulfuric acid attack. RCA-old contained 15% less adhered mortar than RCA-new, which resulted in a higher aggregate density and reduced water absorption. While both RCAs exhibited greater water absorption and abrasion loss than granite, blending them 1:1 in volume with granite reduced these deficiencies to near-control levels. Notably, RCA-old concrete achieved compressive strengths equivalent to the control mix and 8% higher than the RCA-new mix at 28 days. Under sulfuric acid exposure, the RCA-old concrete showed mass loss comparable to the reference mix. Thus, RCA-old can replace 50% of natural coarse aggregate without compromising workability, strength or durability, demonstrating the potential for sustainable reuse of aged demolition waste in sustainable structural concrete. It is worth noting that systematic comparisons between aggregates from aged concrete demolished in the field and freshly cast laboratory specimens are still scarce, but they are crucial for the global reality of RCA production. • RCA from aged concrete had lower mortar content and better physical properties • Natural aggregate-RCA blends reduced water absorption and abrasion loss to near-control levels • RCA-old concrete matched control strength and exceeded RCA-new by 8% at 28 days • Workability kept by pre-wetting aggregates and adjusted superplasticizer dosage • RCA-old concrete showed durability comparable to control under H 2 SO 4 exposure