Maximum efficiency through selective asphalt milling

In the redesign of the A.C. de Graafweg (N241), Aduco is selectively removing the existing asphalt package of both the carriageway and the bicycle path over the entire length of 12 kilometers. This is because the clean milled asphalt will be reused in the new asphalt. The more efficient the milling is, the greater the savings for Boskalis and the environment.

Aduco is a specialist in asphalt milling and stabilization. "In this we are absolutely progressive. And have been since 1978," emphasizes Otto Salomons, Aduco business manager. "We always try to approach a project just a little bit smarter and more efficiently." Boskalis is 20% shareholder in Aduco and basically always calls on the specialist for the asphalt milling component. "During the redesign of the A.C. de Graafweg (N241), we were asked to help think about how to remove the asphalt package as efficiently as possible with a clear separation between the clean and tar asphalt. After all, the clean milled asphalt acts as a raw material for the new asphalt."

Milling Plan

Based on Boskalis' preliminary investigation, a milling plan was drawn up. "Here it is clearly indicated where which type of asphalt is located. It is regulated by law that tar-containing milling asphalt is taken out of the chain and cleaned," says Salomons. "It's up to us to mill out the contaminated asphalt as selectively as possible to prevent clean asphalt from going to the cleaner. The thermal cleaning of the tar fraction from the milling asphalt is quite expensive. The more selective we mill, the better for the 'wallet' and the environment." Speaking of savings, another specialty of Aduco is stabilizing roads and foundations with foamed bitumen, for example. "The milled asphalt is then worked up into a stable and load-bearing foundation on site. It results in far fewer transport movements, double the design life and a thinner asphalt layer. Unfortunately, due to a foundation package containing blast furnace slag, this optimization proved impossible on the A.C. de Graafweg."

62,000 tons

The asphalt of the A.C. de Graafweg is being milled out in several phases. "Although it involves a total of 62,000 tons, we are following Boskalis' schedule in this," says Marcel Hermans, calculator at Aduco. "For each phase and each section we very accurately plan the right machines, so that we achieve maximum efficiency here as well. By the way, all our machines meet the highest environmental class and are no more than 5 years old. In addition, we use organic HVO100 fuel as much as possible."

About the cooperation with Boskalis, the gentlemen are extremely satisfied. "It feels like family. We work as a unit. And that's just very pleasant. Boskalis has its affairs in order and is always mindful of the progress of a project," Salomons notes. "In the event of any stagnation, matters are resolved quickly. That is a blessing for us and for our guys outside as well. After all, they have to be able to get rid of the milling asphalt in a dump truck."