Category 18 April 2019

Recycled asphalt used for the sustainable construction of roads

The Free Hanseatic City of Hamburg wished to progress from using less than 50% reclaimed asphalt pavement (RAP) to using an ambitious 100% RAP in the resurfacing of its roads. The City encouraged innovation in the market by supporting contractors to develop a new, cost effective solution, complying with the city’s sustainability criteria, before going ahead with a restricted public procurement procedure. 

The challenge

The City was motivated by the fact that a recent policy had been implemented which established that the Hamburg’s roads should be repaired using recycled materials. Additionally, the price of bitumen and white aggregates used previously for road construction had increased significantly. The City recognised that construction companies were in a strong position to carry out research and provide an innovative solution.

The measure

Hamburg, Germany felt it would make significant savings by using 100% RAP and that stipulating low-temperature asphalt should be used, which uses less energy and emits fewer CO2 and other harmful emissions.

Bitumen is typically the most expensive product in road construction. Although it makes up just 5% of the physical road, it accounts for 60% of the cost. Additionally, bitumen is an unsustainable oil-based product which cannot be sourced locally, as such its price is very volatile.

The City approached a number of companies and requested that they examine methods to remove and recycle bitumen. Hamburg permitted the testing of potential solutions to be carried out on the City’s own roads and quality was tested by Hamburg’s road construction authority. Field testing allowed an innovative, sustainable solution to be found that would not affect road quality or durability.

Hamburg carried out a public procurement via a restricted tender with five bidders and the company STORIMPEX AsphalTec GmbH, which quoted the lowest price, was awarded the contract. This individual project enabled Hamburg to save 30%, in comparison to the cost of a conventional road resurfacing project.

Lessons learnt

The City of Hamburg engaged in responsible purchasing and actively sought a sustainable, eco-innovative solution. It also saved money and met its legal requirements to use recyclable materials, in turn complying with sustainability criteria. By directly approaching contractors and encouraging them to develop a solution, the success of this project was greatly increased. In a recent road construction tender, the City of Hamburg included the option for applicants to offer a variant solution, which would allow applicants to present this or other possible solutions.

Further deployment

The process requires a certain amount of expertise and the appropriate equipment. The process has also since been patented by STORIMPEX AsphalTec GmbH. The advantages are that the asphalt is significantly cheaper to produce, while the quality and durability of the asphalt are equal to that of conventional asphalt. To ensure that the process is efficient, when carried out on a larger scale, ideally recycled asphalt should be used on roads within the same city or region. The demand for this method in the market has been demonstrated by the fact that cities in Germany, England and Brazil have since shown interest, qualifying this policy for GML 7 on the maturity scale.