Pervious pavements are generally not structurally sound, weak in material strength, and can be easily clogged. Thus, they might only be used in sidewalks, squares, and parking lots, but not for vehicular loads. An innovative eco-technology recently developed in Taiwan uses air-circulated aqueduct frames and impervious Portland cement concrete on top of an aggregate (crushed stone or gravel) base layer to form a structured permeable concrete pavement (called JW eco-technology pavement) can alleviate such problems. The main functions and special features include: (1) The aggregate layer may serve as a detention reservoir to increase flood control capabilities; (2) The stored water may lower pavement surface temperature in summer and help to reduce heat island effects; (3) This eco-technology can prevent water accumulation on pavement surface to improve pedestrian and driving safety; and (4) Exhausts from vehicles may be absorbed by the pavement system and become the nutrients of an underground ecological system.
Through proper designs, the structured JW pavement can possess adequate load bearing capacities as conventional concrete pavements do. Traditional concrete pavement thickness design approaches are proposed to be used as the basic guidelines for determining the required slab thickness. Since the aggregate base course serves as structural bearing layer and reservoir layer, its thickness can be determined as the thicker of the two results based on these design controls. The surface conditions of several JW pavements remain fairly good even after 10 years of service in Taiwan. Evidences indicated that the JW pavement can be successfully used in roadways subject to light traffic under normal geological conditions. However, the subgrade soil underneath the aggregate (or crushed stone) layer warrants further investigations, especially when the soils are suspicious to settlement or may lose shear strength due to wetting. There are still challenges ahead such as to better understand its failure mechanisms, structural capabilities in terms of allowable load repetitions, and other long term performance indices if the structured JW pavement should be used for normal or heavier traffic loading conditions.
