Print Email Facebook Twitter Experimental characterization of storage stability of crumb rubber modified bitumen with warm-mix additives Title Experimental characterization of storage stability of crumb rubber modified bitumen with warm-mix additives Author Wang, H. (TU Delft Pavement Engineering) Liu, X. (TU Delft Pavement Engineering) Erkens, S. (TU Delft Pavement Engineering) Scarpas, Athanasios (TU Delft Pavement Engineering; Petroleum Institute) Date 2020 Abstract One of the main drawbacks of crumb rubber modified bitumen (CRMB) is the storage stability issue. The storage instability of CRMB impedes its further application. This study aims to develop a robust methodology to evaluate the storage stability of CRMB binders using both mechanical and morphological tests. The effects of rubber contents (0, 5%, 10%, 15%, 22% by weight of bitumen) and different non-foaming warm-mix additives (wax-based and chemical-based additives) on the storage stability of CRMB were investigated. Laboratory tests were also performed on the constituents of CRMB to have a deep understanding of the mechanism of storage instability. Standard tube separation tests were conducted on different binders. Both rheological tests and X-ray computed tomography (CT) scan tests were performed on the binder samples collected from different parts of the tube test. Separation indices were developed based on the difference in mechanical property and rubber content from the tube samples respectively. Results show that CRMB with a higher rubber content is more storage stable than that with a lower rubber content. The addition of warm-mix additives is detrimental to the storage stability of the studied CRMB. Rheological tests were performed on the individual constituents of CRMB (i.e., bitumen phase and rubber phase) to understand better the dynamic asymmetry potentially existing within the unstable CRMB binder. Results show that the residual bitumen becomes stiffer while the swollen rubber becomes softer after interaction because of the preferential absorption of light components of bitumen by rubber. The dynamic asymmetry existing between the bitumen phase and the rubber phase of CRMB results in storage instability. When the bitumen phase has similar dynamic properties as the rubber phase, the resulted binder system will be stable. It is possible to manipulate raw material properties and interaction conditions to achieve the desired crossover between two phases of CRMB and hence obtain a storage-stable CRMB blend. Subject Crumb rubber modified bitumenDynamic asymmetryFrequency sweepMultiple stress creep recoveryStorage stabilityWarm mix asphaltx-ray CT scan To reference this document use: http://resolver.tudelft.nl/uuid:5f4fee40-73b7-4211-989c-e75f9f3ec608 DOI https://doi.org/10.1016/j.conbuildmat.2020.118840 ISSN 0950-0618 Source Construction and Building Materials, 249 Part of collection Institutional Repository Document type journal article Rights © 2020 H. Wang, X. Liu, S. Erkens, Athanasios Scarpas Files PDF 1_s2.0_S095006182030845X_main.pdf 2.3 MB Close viewer /islandora/object/uuid:5f4fee40-73b7-4211-989c-e75f9f3ec608/datastream/OBJ/view