Ahmet Buğra İbiş

Porous asphalt (PA) is a type of pavement with an open-graded aggregate that contains higher air voids than the conventional asphalt pavements after compaction, which allows precipitation waters to infiltrate from the pavement surface to the lower layers. The particle loss in the wear layer causes surface deterioration, which affects pavement performance. In addition, the porosity nature of porous asphalt leaves the pavement under the effect of air and water continuously, which accelerates the oxidation rate and affects the surface properties of the pavement. Moreover, these factors can affect the bitumen-aggregate bond strength and cause cohesion degradation within the asphalt film, causing the bitumen to peel from aggregate. The performance of porous asphalt, particularly strength and durability, is greatly affected by compaction temperature. Higher compaction temperatures can reduce the air voids of the mix, so the required mix densities may not be achieved. In this study, the particle loss of porous asphalt samples prepared at 3 different compaction temperatures by using unmodified bitumen, SBS®, Elvaloy®, and Sasobit® modified bitumen was investigated and the optimum mixing and compaction temperature was determined.

In recent years, studies on porous asphalt have gained more importance and countries are conducting various studies in order to improve the engineering properties of this type of pavement. As a result of these studies, each country developed its own standard and therefore different optimum bitumen content (OBC) determination methods emerged. This paper investigates the determination of the optimum bitumen content of porous asphalt samples prepared by using different aggregate types and polymers by the methods implemented in Turkey and in other countries. The results have shown that the application of each method yielded different bitumen content.

Porous asphalt pavement is defined as an asphalt concrete that is designed with open gradation aggregate which helps in removing the water with an air void content of about 20% by creating drainage channels. Open gradation consists of large amounts of coarse aggregates and small amounts of fine aggregates. The water is drained due to this hollow structure, this air void content in the porous asphalt mixture which inevitably decreases with time is the main parameter affecting the service life as well as the structural and functional performance. Moreover, the reduction in air void content is one of the main reasons for the loss of permeability in porous asphalt pavements and this lead to the increase in pavement density under heavy traffic conditions. Each country has its own technical asphalt specification involving the required compaction energy and temperature. This study involves the effect of compaction temperatures and numbers on the air void in porous asphalt pavements prepared with 50/70 penetration grade bitumen. As a result of experimental studies, it has been observed that the reduced compaction temperature and the number of compaction (energy) increase the air void level in porous asphalt pavements.