Sammendrag
This study examines different options of production of asphalt aggregates to create durable and environmentally friendly roads. With increasing traffic loads and climate change, it becomes crucial to develop methods that ensure robust roads while respecting the planet’s limited resources. This thesis explores how the production of aggregate material with and without VSI (Vertical Shaft Impactor) impacts the correlation between nordic abration (AN ) and flakiness index (FI). The relationship between AN and FI is studied for materials at different crushing stages, and with varying quality. The results indicate low causality between the methods, highest at high FI. To identify the effect of grinding on different materials, materials from Tau, Jelsa, and Dirdal were tested before VSI, after one round in VSI, and after two rounds in VSI. The results show that the crusher has a significant effect on the material, most in the first step, less in the second. Petrographic thin section analyses can identify mineralogical structures and content that limit the material’s performance. In summary, flakiness, nordic abration, and petrographic examination indicate that it is not advisable to over-process aggregates. Simultaneously, the results from different crushing stages indicate that the materials are rounded after other crushers than VSI, such as the cone crusher. It is more energy efficient, produces less fine particles, and requires less maintenance compared to the VSI crusher. Therefore, it would be beneficial for aggregate producers to limit the use of VSI and instead utilize other crushers for shaping. For the Tau quarry, it may be an option to replace VSI with a cone crusher or upgrade to a newer MK1 crusher and remove VSI from the production process. This would ensure that Tau continues to produce high-quality aggregate material while considering resource use. This thesis was written in collaboration with Norsk Stein, and is part of the research project “Asfaltdekkers levetid“.