Innovative Longitudinal Joints Between New and Old Porous Asphalt

For both lane and carriageway wide maintenance of Porous Asphalt (PA) in the Netherlands, contractors increasingly make use of so called joint protectors to prevent premature damage to longitudinal joints in the warranty period of 7 years. Mostly strips of bituminous material are placed on those joints or the joints are poured with hot bitumen and sanded, but sometimes no measures are taken. Those joint protectors can eventually go smooth and/or shiny. Rijkswaterstaat (RWS) gets relatively many complaints of especially motorcyclists, because they are more vulnerable and driving in the middle of the lane where sometimes the joint is. Claims are also made. Sometimes joint protectors are mistaken for "ghost" marking, especially during rainfall, because they are more visible than the mark. In short, RWS was not satisfied with the current joint protectors. In order to remedy this, RWS started a competition to come up with improvements. Contractors came with 11 ideas that were assessed on skid resistance, shine, traffic hindrance, environmental friendliness and costs. Five winners were selected by an independent jury. Those prize winners were able to demonstrate their idea on a PA test section on motorway A59. Cores from these test sections, drilled on the joint, were investigated in the laboratory. One year after construction the joints were visually inspected, and the skid resistance and horizontal water drainability was measured. This paper discusses the winning ideas, the construction of the test sections, the laboratory and field tests and results.