Effect of organic reagents on high temperature rheological characteristics of organic rectorite modified asphalt

Abstract The molecular structure of organic reagents has a great effect on properties of organic rectorite (OREC) modified asphalt binder. This paper aims at comparing the influence of molecular chain length and benzyl group on the high temperature rheological characteristics of OREC modified binder. Here, three organic quaternary ammonium salts, including dodecyl trimethyl ammonium chloride (DTAC), dodecyl dimethyl benzyl ammonium chloride (DBAC) and octadecyl trimethyl ammonium chloride (OTAC), were selected as REC modifiers to prepare ORECs. These ORECs were then employed to modify base binder, respectively. The X-ray diffraction (XRD) test and thermogravimetric (TG) test were conducted to study the structure characteristics and thermal behavior of ORECs and corresponding modified binders. The high temperature rheological behavior, rutting and stress susceptibilities of OREC modified binders were evaluated by the temperature and frequency sweep tests, multiple stress creep recovery (MSCR) test. Results indicate that, the organic reagent affects the rheological behavior of OREC modified binder not only by enlarging the basal spacing of REC (specific surface area), but also directly by specific functional groups (e.g. benzyl group). Moreover, the organic reagent with longer molecular chains (18 carbon atoms) or containing benzyl groups is conductive to the improvement in elastic property and stiffness, and reduction in rutting and stress susceptibilities of OREC modified binder. The comparison demonstrates that DBAC containing benzyl groups exhibits better effect. Therefore, organic reagents containing benzyl groups are preferred to obtain OREC modified binder with excellent high temperature property.