Sustainable cement substitute on project Noordeindseweg

We work in a construction team with the municipality of Delft and carry out this project as sustainably as possible. For example, we reuse about 90% of the existing paving and we work with green electricity and partly with electric equipment. This project fits well with our sustainability vision, in which we aim for 50% circular, 100% CO2-neutral and 100% waste-free construction by 2030.

Foam bitumen

Due to its sensitive peat soil, the old Noordeindseweg has suffered many cracks and irregularities. Foam bitumen stabilisation therefore provides a solution. We mix the outdated asphalt road and add foamed bitumen and the sustainable cement substance Eco₂cem in the milling material. This solution can move more easily with deformations, without causing the construction layer to crack. Ideal for road constructions on peat substrates.

Science and practice

The Eco2cem sustainable cement was chosen after research by TNO, which brought science and practice together. Their literature research concluded that geopolymer cements are not yet suitable for an in-situ dry application, so the choice fell on the sustainable cementitious agent Eco₂cem.

TNO also verified the mixture design for the foam bitumen stabilisation. This independent check provides additional design security for the municipality of Delft and Ballast Nedam.

Extensive tests for high quality asphalt

The asphalt mixture we are using on the Noordeindseweg consists of 60% asphalt granulate and 40% slag granulate, plus 2.5% bitumen and 1% ground granulated blast furnace slag: the sustainable cement substance Eco₂cem proposed by TNO. We want to reuse as much material as possible, but the quality of the road surfacing must not suffer. That is why we use data and technology to create the best solution:

• With core drilling, radar and bearing strength measurements, we investigated the quality of the old pavement. These results allowed us to confirm that we can reuse materials to the maximum extent. This means that part of the existing foundation can remain in place and retain its function. With the remaining foundation and asphalt granulate, we make the foam bitumen stabilisation. The road surface will also be given a sustainable asphalt overlay, 60% of the material consisting of recycled asphalt.
• Drill core investigations showed that the existing bonded slag foundation contains a steel reinforcement. We obtained the exact depth from radar measurements. This data was processed into a detailed map, which we used to prevent the chisels from being damaged during milling.
• The test pieces of the mixtures were examined in DIBEC's laboratory so that we could determine the compressive strength, splitting strength, stiffness and fatigue strength. This ensures an optimal mixture choice with the right balance between technical and environmental sustainability.

When the Noordeindseweg is renewed, DIBEC Materiaalkunde will again perform tests to verify the quality. We do this by drilling and examining cylinder samples. One year after completion we again perform fall weight deflection measurements to check whether the overall bearing capacity of the Noordeindseweg has improved.

After the work is performed by our road construction specialists, in the summer of 2022 the bumpy, outdated road will be transformed into a smooth road that will last for years to come.