Mechanical Performance, Absorption Characteristics, and Cost Implications of Recycled Concrete Aggregate Masonry Blocks in Bangladesh

Construction and demolition (C&D) waste management is a critical challenge in Bangladesh, yet the reuse of concrete debris as recycled concrete aggregate (RCA) remains limited. This study provides an integrated assessment of mechanical performance, water absorption, and production cost of masonry blocks incorporating RCA—sourced from on‐site of a brick‐aggregate concrete structure—as a replacement for conventional crushed brick aggregate at five levels (0%, 25%, 50%, 75%, and 100% by coarse aggregate volume) in a 1:2:4 (cement:sand:coarse aggregate) mix with a water‐to‐cement ratio of 0.45. Blocks (254 mm× 127 mm× 76 mm) were cast, moist‐cured for 28 days, and tested per ASTM/ACI standards. Results show a slight unit weight decrease (1986–1970.8 kg/m 3 ), increased water absorption (10.57%–16.47%), and reduced compressive strength (26.6–21.5 MPa, ~19% drop) as RCA increased from 0% to 100%. Ordinary least squares (OLSs) regressions yielded strong fits for all three properties ( R 2 = 0.95–0.99). All mixes exceeded Bangladesh’s first‐class brick strength (~17.2 MPa) and maintained absorption below 20% (BDS 208:2002). Indicative ASTM C90 absorption suggests medium‐weight compliance up to approximately 50% RCA. Production cost dropped to approximately 43% with 100% RCA under base‐case on‐site processing conditions. A 25%–50% RCA replacement range is recommended, offering adequate performance, indicative standards compliance, and approx 11%–22% cost savings, with higher replacement viable using absorption‐mitigating measures. Future work should include ASTM C140/C90 testing on standard‐sized specimens, multisource RCA characterization, and durability assessments.