Low temperatures rheological analysis of a bituminuos binder added up with fibres

The Authors study the experimental results of a research on the low temperature rheological performances of a medium grade bituminous binder added up with fibres for the realization of SMA (Split Mastix Asphalt or Stone Mastic Asphalt). In this paper, by means of the B.B.R (Bending Beam Rheometer) apparatus, micro fibrillated and/or pulverized fibres are supposed to be used instead of the conventionally called “pellets”; the latter are usually produced in the industrial field and, since they have been used in the first part of the study, they seemed to be mixable not in an easy way with binder, as long as the temperature was not very significant (T<200°C). As a consequence, it makes sense to use cellulose, rock wool and rubber pounce fibres. The fibres used in laboratory percentage with reference to binder were defined considering both the minimum percentage suggested by literature on SMA and the objective data on the percentages more suitable from the point of view of formability and rheological response of binder. Several laboratory tests were performed on binder added up with fibres from 2% up to 6%, with mixing temperatures varying from 130 to 200°C. The low temperature (-10, -15, -20, -25°C) tests by means of B.B.R. allowed to give a characterization of the binders from a performance point of view, giving also some interesting information on their use for the preparation of SMA.