Comparison of the effect of recycled crumb rubber and polymer concentration on the performance of binders for asphalt mixtures

Abstract

Crumb rubber modified binders are environmental-friendly alternatives to polymer modified bitumens in asphalt mixtures. This paper compares the performance of both types of binders with different modifier contents. Six binders were characterised by conventional tests and analysed using the UCL method. This method evaluates different properties of binders regarding their role in asphalt mixtures (cohesion, water and thermal sensitivity and resistance to ageing). Results showed that i) crumb rubber concentration has to be higher than that of SBS-polymers in order to obtain a similar performance to that of SBS-polymer modified bitumen; ii) crumb rubber modified binders are more stable than SBS-polymer modified binders in terms of modifier concentration; iii) crumb rubber modified binders exhibited less water sensitivity and similar thermal and ageing susceptibility to SBS-polymer modified binders; iv) linear relationships have been found between modifier concentration and the properties studied for both kind of binders. RESUMEN: Comparación del efecto de la concentración de polvo de neumático reciclado y polímeros en el comportamiento de ligantes para mezclas bituminosas. Los betunes modificados con polvo de neumático (PN)son alternativas ambientalmente sostenibles a los betunes modificados con polímeros. Este artículo compara el comportamiento de ambos tipos de betunes con varios contenidos de modificador. Para ello, se caracterizaron seis betunes mediante ensayos convencionales y método UCL. Este método evalúa propiedades de ligantes para su uso en mezclas bituminosas (cohesión, sensibilidad al agua, térmica y al envejecimiento). Los resultados muestran que i) la concentración de PN ha de ser más elevada que la de polímeros para obtener comportamiento semejante; ii) los betunes con PN son más estables ante cambios en la concentración de modificador que los betunes con polímeros; iii) los betunes con PN presentan menor sensibilidad al agua y equivalente susceptibilidad térmica y al envejecimiento que los betunes con polímeros; iv) se encontraron buenos ajustes lineales entre la concentración de modificadores y la evolución de las propiedades estudiadas.

Optimisation of bitumen emulsion properties for ballast stabilisation

“…Bitumen emulsion dosage and properties (29), as well as the aggregate gradation used, can potentially affect the quantity of BE achieved during the application and could also influence BSB mechanical behaviour. Thus, with the aim of evaluating the influence of such variables on the application method and on the main parameters affecting in-field ballast performance, a series of laboratory tests were carried out: (i) Flowability tests and (ii) Confined compression tests using the Precision Unbound Material Analyser (PUMA) apparatus.…”

Reclaimed Polymers as Asphalt Binder Modifiers for More Sustainable Roads: A Review

“…For modification through the wet process, the reaction is composed of two simultaneous processes: The partial digestion of the rubber into the bitumen, and the adsorption of the aromatic oils available in the binder into the polymer chains causing the rubber to swell and soften [69][70][71][72]. However, increased temperatures or mixing times may lead to excessive degradation or aggregation of crumb rubber along with bitumen aging, which will cause a decline in the performance of the modified binder [68,70].…”

Analysis of the sensitivity of the impact resonance frequency test as a tool to determine the elastic properties of bituminous materials

“…These mechanical vibrations are transformed into signals and transferred to the frequency domain by using the fast Fourier transform algorithm (6), in order to determine the resonance frequency of the material. As this parameter is directly related to the stiffness of the material [1], it can be used to define its modulus and to detect the presence of internal defects. In this respect, it is worth noting that bituminous mixtures have a certain damping due to their partly viscous nature, and this should be taken into account when determining the resonance frequency.…”

“…This is also the main reason why new elements such as polymers, crumb rubber or thermal power plant ashes (1,2) are being incorporated into bituminous mixtures, in order to achieve more durable pavements that have minimal impact on economic and social activities. In this respect, determining the degree of deterioration of the materials used in the construction of these infrastructures can be of considerable value when attempting to identify the suitability of these new components and the optimal time to conduct rehabilitation activities.…”