Runoff Reduction Performance of Permeable Pavements: Effects of Block Structure and Joint Filler Characteristics

Rapid urbanization and climate change have increased the extent of impervious surfaces, intensifying urban flooding and disrupting natural water circulation. To address these challenges, Low-Impact-Development techniques have been adopted, with permeable pavements serving as effective decentralized stormwater systems. This study evaluates the runoff reduction performance of permeable pavements featuring different upper block structures under identical subbase conditions. Two types of blocks were tested: Block A, an interlocking joint-type block that allows infiltration through its joints, and Block B, a monolithic permeable block that enables direct infiltration through the block surface. Artificial rainfall tests were conducted for 60 min at rainfall intensities of 42 mm/h (2-year) and 66 mm/h (10-year). Both blocks reduced runoff and delayed the equilibrium time compared with those of the impervious pavement. Block B exhibited a lower equilibrium flow rate and a longer recession period owing to uniform infiltration and gradual drainage through the joint filler. These findings indicate that the block structure and joint material properties significantly affect runoff reduction performance.