Towards simplified grading of reclaimed fired clay bricks: links between density, water absorption, and strength

Reclaimed bricks are increasingly considered in circular construction; however, their substantial variability highlights the need for improved characterization and grading to enable reliable reuse. This study investigates the relationships among net density, 24h water absorption, initial rate of absorption (IRA), the water absorption coefficient (A_w), and compressive strength (f_b) in reclaimed bricks, with the aim of evaluating net density and 24h water absorption as practical screening parameters for mechanical performance. The results show strong correlations between fb and both net density and 24h water absorption, while net density and 24h water absorption are themselves very strongly correlated. In contrast, Aw shows only moderate correlation with f_b, indicating that it is less representative of mechanical performance. These findings suggest that net density and 24h water absorption are suitable practical screening parameters for strength assessment, supporting the development of simplified grading approaches for reclaimed bricks in circular construction.