Special asphalt in Castricum: In close cooperation with the municipality
“This approach must be the future.” That's how it sounded on our construction site in Castricum. During a refurbishment project, a new red asphalt mixture was developed that scores high in terms of sustainability. Ballast Nedam developed this together with the researchers from the DIBEC Materials Science department and the municipality.
The reason for the redevelopment of the Oranjelaan was the need for a traffic-safe environment for cyclists and local residents. No superfluous luxury, with a large school around the corner and a bus stop, railway and nursing home in the street. In addition to improving road safety, two other aspects were of key priority: sustainability and a close cooperation.
Thinner and more durable - with the same strength
Ballast Nedam carries out asphalting work for the municipality of Castricum within a framework contract. We have based the collaboration within this refurbishment project on this basic agreement. “We thought: what if we consider and design the entire construction from scratch?” says Thomas Snelderwaard, Project Manager at Ballast Nedam Road Specialties. “It started with an inventory. What do we have in-house? And what calculations can we make? DIBEC has calculated the pavement constructions on durability and lifespan based on the desired principles.”
For this project, the choice was made for a CO2-saving paving construction that does not affect the lifespan. The asphalt chosen is in line with the ambitions of the municipality and scores high on sustainability due to the reuse of various materials. “We replaced the sand foundation with hydraulic mixed granulate,” says Thomas. “The sand released is reused within the municipality. Also, we can apply a thinner asphalt package because DIBEC has calculated with a load-bearing foundation and more stable asphalt mixtures. As a result, we only need a layer thickness of 120 millimeters in total. That is a big difference, because according to the municipality's research, no less than 170 millimeters of asphalt would be needed here. In short, a huge reduction of CO2 by using fewer raw materials.”
Special red asphalt on the bike paths
A highlight of the redesign is the new cycle path that frames the road on both sides. A new mixture has been developed for these cycle paths, in which the old red asphalt is reused. Ballast Nedam and DIBEC extensively investigated whether the asphalt was suitable for this. The result? A first in the Netherlands. This method saves red pigment, red stone chips and bitumen. That is a good starting point, since we don't have to extract an extra oil product from the ground. The environmental impact and CO2 emissions have been reduced by more than 50% during the production of this red asphalt mixture compared to a new mixture.
A large part of the new cycle paths has become less red since the redevelopment and tends more towards red-brown. This is due to the reuse of the old asphalt and the use of black binder. Thomas: “This means that the old asphalt returns in exactly the same place. This way of working will be the future.”
Redesign from a triangle
The old bus stop has disappeared and now offers plenty of space for greenery. In the autumn we will plant more than twenty trees and 300m2 of perennials will be placed on the large roundabout. In addition, old tiles in the footpath have been reused and LED lamps have been installed.