Sample preparation effect on measured rheological properties of bitumen using Dynamic Shear Rheometer

Sammanfattning: Through improved bitumen characterization, which will increase the road'sdurability, stability, and performance, pavement engineering can apply thesustainability notion that should be followed in all disciplines nowadays. The newtechniques distinguish between the rheological properties of bituminous binders as a function of loading time and temperature to depict real-world behavior rather than only considering empirical properties. The complex shear modulus of bitumen, that can be measured using a dynamic shear rheometer (DSR), describes the stiffness and degree of viscous and elastic behavior at a given frequency and temperature.Even though EN 14770:2012 primarily describes the procedure of specimenpreparation and conditioning, various factors related to DSR testing setup may resultin nonconformity. Therefore, an investigation was conducted to review several areas of test method practices and the underlying impact on results based on data from round-robin tests on bitumen types 50/70 in 2017 and 20/30 in 2018, as well as polymer-modified bitumen 45/80-55 in 2019 and 2020. The variability in testing conditions and how the testing conditions may affect the measures, as well as the precision of the test technique, are statistically examined. After that, a two-level, three-factor experimental design was used to investigate the effects of the oven setting temperature, bonding temperature to the rheometer, and trimming on |G'| and δ. This involved estimating the main and interaction effects of the factors from replicated runs as well as calculating the standard errors of the effects.The results based on RR-test data demonstrate that ignoring the extreme valuesdue to the use of inappropriate plate geometry or the small number of laboratories involved improves the accuracy range of phase angle to a repeatability limit of r = 1-2° and reproducibility limit of R= 3-6° for tested bitumen. While for |G'|, thecoefficient of variation under repeatability improves to a range of 2-8%, and thecoefficient of variation under reproducibility varies between 7 and 18%. None ofthe studied bitumen were significantly affected by waiting times of longer than 72h. Furthermore, no significant variations were found between the most often usedbrands of equipment and sample manufacturing procedures. With results usuallyfalling between the upper and lower reported values, 15 minutes appears to be asuitable equilibrium duration. According to the correlation test based on RR- data,the bonding temperature, and sample production temperature exhibited a significant link in more test combinations than in other sample preparation phases. Finally, in the second part of the study, the investigation of the effect of these factors together with trimming on results showed a significant difference in trimmed and untrimmed samples when PP08 is applied. The bonding and oven heating temperatures take on varying degrees of significance depending on the materials and tested temperatures.