Sample preparation techniques on dynamic shear rheometer testing: round robin tests on bitumen

Three interlaboratory tests conducted by European laboratories were studied, in which 37 laboratories participated in 2018, rising to 46 in 2019 and 2020. A RTFO-aged neat bitumen 20/30 and PMB 45/80-55 in RTFO-aged and unaged conditions were tested using a DSR at frequency of 1.59 Hz with PP08 and PP25 geometries at temperatures ranging from 10°C to 65°C. To assess variation in numerous areas of test method EN14770:2012 practices and the underlying impact on test outcomes, a statistical analysis on G* and δ is reported. The finding emphasises the need of using a detailed written sample preparation protocol to limit operators’ latitude while conducting tests. The statistical investigation suggests that the sample mounting onto rheometer stage and the sample manufacturing oven setup process require more attention. Furthermore, δ precision outperforms the EN14770:2012 criteria; nevertheless, |G*| precision does not match EN14770:2012 for all the testing combinations.