Development of a Photocatalytic Infiltration Pavement Block for NOx Removal and Rainwater Retention

This study presents a photocatalytic infiltration pavement block designed to combine roadside NOx removal with rainwater capture and temporary storage. TiO2 and styrene–butadiene rubber (SBR) latex were incorporated into the pavement block to provide photocatalytic functionality, and direct infiltration holes were introduced to capture surface runoff, enable temporary storage, and promote delayed subgrade drainage. The effects of TiO2 and SBR latex on compressive strength and NOx removal were evaluated, while rainwater infiltration performance was examined using acrylic panels with different hole diameters, hole-area ratios, slopes, and V-groove treatments. The use of SBR latex improved the compressive strength of TiO2-containing mixtures, with T10-L5 showing an 8.1% increase compared with the corresponding non-latex mixture. The same mixture achieved the highest NOx removal efficiency, reaching 73.0% after 60 min of UV exposure. In the infiltration test, the 5 mm hole configuration gave the most stable runoff reduction, and lattice-type V-grooves improved water capture by connecting adjacent holes and guiding surface flow. A field-scale trial installation confirmed that the integrated infiltration–retention system suppressed visible ponding and runoff, provided delayed subgrade drainage, and maintained pavement stability under vehicle loading. The findings indicate that the proposed block system can provide combined air-purification and stormwater-control functions.