Influence of sodium and organo-montmorillonites on the properties of bitumen

This paper investigated the influence of sodium and organo-montmorillonites on the properties of bitumen. The organo-montmorillonite (OTAC+ Mt) was obtained by reacting the sodium montmorillonite (Na+ Mt) with octadecyl trimethylammonium chloride. Bitumen binder samples with a content of 4 mass% of montmorillonite were prepared in a laboratory high-shear mixer. The rheological behaviour and ageing properties of the bitumens were investigated with a dynamic shear rheometer. The dispersion state of montmorillonite in bitumen was determined by X-ray diffraction and CT scanning. The two montmorillonites behaved differently in the bitumen. The intercalated structure of OTAC+ Mt was observed in the bitumen. However, the Na+ Mt existed as particles at micrometer scale. Contrary to Na+ Mt, OTAC+ Mt significantly influenced the rheological behaviour and the ageing properties of bitumen, due to the good compatibility between the organo-montmorillonite and the bitumen used in this study.