Does the wet addition of crumb rubber and emission reduction agents impair the rheological performance of bitumen?
Crumb rubber modified bitumen (CRMB) is a promising solution for recycling waste tyres and improving asphalt performance. Nonetheless, higher temperatures are usually required during mixing, which increases the emission of volatile organic compounds (VOCs) that can potentially cause harmful health effects on workers due to their toxic and carcinogenic properties. Emission reduction agents (ERAs) have been developed to address this issue. However, limited scientific evidence is available regarding their impact on the rheological performance of CRMB, which makes the selection of the most suitable ERA challenging. This study investigated the effects of three ERAs on the physical and rheological properties of CRMB: steam-activated carbon/charcoal (AC), fly ash-based geopolymer (GFA), and Portland cement paste (PCP). In addition to penetration and softening point tests, a dynamic shear rheometer (DSR) was used to evaluate the rheological properties of the samples in the frequency and temperature domains and to perform the multiple stress creep recovery (MSCR) and linear amplitude sweep (LAS) tests. The results revealed that the three ERAs increased the stiffness of CRMB: penetration reduced and softening point, penetration index, and viscosity increased. This stiffening effect caused a drop in the fatigue resistance measured in the LAS test. Out of the three ERAs evaluated, AC clearly induced the greatest changes in binder properties. However, MSCR results, crossover frequency, R-value, Glower-Rowe parameter, and ΔTc were less sensitive to the addition of ERAs. It was concluded that the addition of GFA and PCP did not impair the physical and rheological properties of CRMB, yielding results comparable to those of a PMB. However, AC may introduce issues during mixing and service life due to the increase in viscosity and the reduction in fatigue resistance.
Source (journal)
Construction and building materials. - Reigate
Reigate : 2024
417 (2024) , p. 1-11
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The author-created version that incorporates referee comments and is the accepted for publication version Available from 13.09.2024
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CRUMBit Phase 2.
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Publications with a UAntwerp address
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Creation 19.02.2024
Last edited 19.02.2024
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