Drop-on mixtures for road marking systems are safety-relevant parts of highway equipment (street furniture). For a performance-guaranteed functionality and durability there are requirements in the technical regulations according to particle size distribution as well as particle shape, particle transparency and surface characteristics. It was aim of this research project to validate an optimized granulometric test approach by adaption of a modern digital-optic measurement method for higher quality assurance. Another target was the development of test methods for an analytic identification of coatings or treatments of glass bead particles. Material basis for the development and validation of test methods were a choice of representative commercially available drop-on materials of Type I and II - approved in German road system - and their basic materials. The project was supported by a mentor group under BASt chairmanship. Resulting from several granulometric investigations a very high-definition as well as differentiation potential of the digital-optic measurement method could be validated for the investigated basic materials. The traceability to sieve testing as conventional screening method could be validated. On the basis of DIN EN 1423 criteria with the help of several shape- and reflection parameters determined by the new optical method also continuative options for an improved quality determination seems to be possible. A subsequent differentiation of drop-on material mixes could be reached in passable precision. The conclusions made were found from comparison between test results of the basic materials and the results of the investigation of the relevant readily mixed drop-on materials. For an improved quality system it is recommended to investigate the basic materials glass beads and antiskid aggregates as well as the relevant final drop-on product with the help of all shape- and reflection parameters delivered by the new digital-optic measurement method. In addition to these research results indication for further and continuative test potential to improve quality control and assurance could be detected. Besides the granulometric and transparency investigations from a second broad analytical approach special adapted methods based on the TOF-SIMS-methodology, Headspace-GC/MS and HTD-GC/MS method could be developed and validated for the analysis of coated or treated glass bead surfaces. Also these surface analyzing tools could be validated by relative comparison between the results for coated/treated and non-treated reference drop-on materials as well as analysis of pure coating materials. First investigation results using the advantages of surface Zeta-Potential gave indications for a high performance-describing potential of this methodology. (Author/publisher)
Abstract