Influence of aluminate coupling agent on low-temperature rheological performance of asphalt mastic

In order to improve the low-temperature rheological performance (LTRP) of asphalt mastic, aluminate coupling agent (ACA) and stearic acid synergist (SAS) were employed in this research. Three factors, which are the ratio of filler to asphalt (F/A), the dosage of ACA (percentage by weight of mineral filler) and the mass ratio between ACA and SAS, were considered, and the testing program is arranged by an orthogonal experimental design method. The effect of the three factors on LTRP of asphalt mastic was firstly investigated by changes of creep stiffness S, creep rate m-value and S/m at different low temperatures, then by the variations of dissipation energy ratio (DER). Analysis of Burgers model parameters is also conducted. The test results show that, comparing with unmodified asphalt mastic, the asphalt mastic modified with ACA (by means of SAS) is observably improved in LTRP and the improved effect at the ratio of 1.0 (Mineral filler to asphalt), the dosage of aluminate coupling agent being 1.5% by weight of mineral filler and the mass ratio between ACA and SAS being 2:1.0 is ideal.