Plastics Coated Pavement: Characterization of Combinations
Many pavements in cities and inside buildings are coated. Cracks, forming in these coatings over time, are ubiquitous. Our customer needed insight into how and when these cracks form and which role the employed materials play.
In this project the coating consisted of plastic material filled with fine gravel. As a base material asphalt and concrete were treated. It is noteworthy that all these materials are by themselves composites.
We characterized coating material and base material separately. For this purpose we designed tensile test specimens. The picture shows the design we used for the coatings. It featured tabs and rather short shoulders. We used a relatively long parallel length for a precise strain measurement by video extensometry.
Then we manufactured these specimens from blocks of coated pavements. First we cut strips of coating and base material from the blocks. Second we machined specimens from the strips using a CNC mill. At last we painted the surface black and added white strain marks.
The picture shows coating specimens positioned where they were taken from in the pavement block. Below the specimens, asphalt base material is visible. The rest of the visible surface is gray coating material.
For characterizing each material individually, we performed and evaluated tensile tests at various temperatures. The diagram on the right shows strain-stress plots for a coating material at some temperatures representing the four seasons. The x-axis showing strain is logarithmic. The results illustrate the strong temperature dependence of the behavior, which was observed with most tested materials. In addition we performed some thermo-mechanical tests to investigate the interaction between coatings and base materials.
In this study we provided these results:
- the temperature dependent behavior of coating systems
- insight into mechanisms of crack formation
- good/bad pairings of coating and base material
- guidelines for the application of coatings