Study of the Shear Stiffness of Bituminous Mastics Incorporating Recycled Glass Fillers

This paper studies the effect of recycled glass (RG) filler on the shear stiffness of mastics (mixture of bitumen and filler) in the linear viscoelastic domain (LVE). The research project was carried out at the Laboratory of Roads and Bituminous Materials (LCMB) of the École de technologie supérieure (ÉTS) using a new experimental device called the annular shear rheometer (ASR). The complex shear modulus G* of bitumen and mastics were measured under various temperatures and frequency conditions (from −25 to 45 °C and from 0.03 to 10 Hz). Two types of RG fillers (crushed glass and micronized glass) and a reference limestone filler were used to manufacture the PG70-28 based mastics. The complex coefficient of reinforcement \({{{{R}}}_{{{M}}}}^{{*}}\) was used to compare the shear stiffness of RG mastics with a limestone-based mastic. Results indicate that the RG filler effect is important at high temperature and/or low frequency where no significant effect was observed at low temperature and/or high frequency. Moreover, the filler size gradation seems to have most influence on the viscoelastic properties of the mastics at high temperature. Overall, it was shown that RG fillers are suitable for improving mastic shear stiffness in a pavement structure.