Unraveling the Physico-chemical structure of Reacted and Activated Rubber

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Unraveling the Physico-chemical structure of Reacted and Activated Rubber

Chaitanya Gubbala, Vinay H. Nanjegowda, Krishna Prapoorna Biligiri, and Jorge B. Sousa

ABSTRACT: Reacted and activated rubber (RAR) is a new generation enhanced asphalt-rubber (AR) material developed for the preparation of rubberized mixtures using the dry process. Several laboratory-based performance studies indicated improved mixture characteristics of RAR modified mixes over conventional AR mixtures. Further, RAR implemented roadway sections across the globe have outperformed the conventional ones by at least two to three times in terms of durability. However, there are limited studies related to the physicochemical characterization of RAR material. Thus, the main objective of the study was to evaluate the physicochemical characteristics of RAR through state-of-the-art material science techniques. The scope of the effort encompassed the following tests: attenuated total reflection (ATR) based infrared spectroscopy (IR), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). The ATR-IR peak results indicated that the RAR product is a blend of complex organic and inorganic compounds. Materials such as crumb rubber, activated mineral binder stabilizer (AMBS), asphalt, and hydrated lime (HL) were identified as the major ingredients. The SEM analysis depicted that RAR is inclusive of different sized particles with non-uniform agglomeration. RAR was found to be 64.20% crystalline in nature based on PXRD results. The TGA test results exhibited percentage mass loss between different temperatures, which were attributed to the decomposition of oils and rubber components in the RAR material.

KEYWORDS: Reacted and activated rubber, Infrared spectroscopy, Powder X-ray diffraction, Scanning electron microscopy, Thermogravimetric analysis.