Mechanism of Interaction of Asphalt Cement with Crumb Rubber Modifier

Abstract

The nature of the interaction process between asphalt cement and crumb rubber modifier (CRM) has not been fully understood. Two main types of mechanisms that affect the produced binder properties are reported: particle swelling and degradation (devulcanization and depolymerization). These mechanisms occur as the binder is subjected to different combinations of interaction time and temperature. Insight into the mechanisms by which the interaction between the two materials takes place through monitoring the changes in the rheological parameters of the binder is provided. The effects of the interaction process variables, time and temperature, are explained. The effect of CRM properties, including particle size and material source, is also discussed.

Improvement of Asphalt Binder by Recycling of Waste Tire Rubber

“…After that, the softening point was decreasing gradually this can be attributed to the particles of WTR were decomposed at temperature above 200 o C which causing reduction in binder viscosity. These results are agreement with finding of Zanzotto and Kennepohl (1996), Abdelrahman and Carpenter (1999) and Rahman (2004). …”

Viscosidade rotacional de ligantes asfálticos modificados de mesmo grau de desempenho

“…Para alguns tipos de modificadores como os terpolímeros reativos, estudos (Polacco et al, 2004) mostraram que o tempo de reação entre o modificador e o ligante asfáltico deve ser mantido dentro de um determinado limite, pois, caso este controle não seja realizado, a viscosidade aumentará significativamente e, assim, a retirada do tanque de armazenamento e a utilização do ligante asfáltico modificado em campo serão inviáveis. Tal fenômeno de reação continuada do modificador com o ligante asfáltico também ocorre no processamento do asfalto-borracha (Abdelrahman e Carpenter, 1999) Além destes limites tradicionais, outras relações também são utilizadas para se estimar as temperaturas de usinagem e de compactação de ligantes asfálticos modificados. No caso do ligante asfalto-borracha moída, por exemplo, a Especificação de Serviço 112/2009 do DNIT menciona que a temperatura de aquecimento deve estar entre 170°C e 180°C e que a temperatura mínima recomendável para a compactação é de 145°C.…”

Rubberised bitumen manufacturing assisted by rheological measurements

“…The higher processing conditions would normally cause oxidative age hardening of base bitumen and increase complex modulus but this effect is not as dominant as the depolymerisation and devulcanization of the rubber particles and the subsequent reduction in complex modulus. Additionally, the lighter components which were absorbed by the rubber during the swelling process would be released back into the liquid phase of the bitumen during the depolymerisation/devulcanization process further decreasing complex modulus (Abdelrahman and Carpenter 1999).…”