Effects of flat and elongated aggregateson the performance of porous asphalt mixture

Four flat and elongated(F&〓 E)contents(0%, original, 30%, and 40%)were investigated to evaluate the effects of F&〓 E particles on the performance of porous asphalt mixture(PA). Laboratory tests including volumetric determination, two-dimensional image analysis, Cantabro loss tests, breakdown tests, and permeability tests were conducted to evaluate the volumetric properties, the state of stone-on-stone contact, durability, skeleton stability and permeability of PA, respectively. The test results indicate that the F&〓 E content was a significant factor for total air voids, aggregate skeleton break down, and permeability. The functionality, rutting resistance, long-term durability, and skeleton stability decrease with the increase of F&〓 E content since F&〓 E aggregates in porous asphalt mixtures have a tendency to breakdown. Compared with traditional dense graded mixtures, PA is more sensitive to the F&〓 E content due to an open graded aggregate structure. Therefore, the stricter requirement for F&〓 E content should be met for porous asphalt mixtures than the one for traditional dense graded mixture.