Rheological Behaviour of WMA-Modified Asphalt Binders with Crumb Rubber

Abstract

Crumb rubber (CR) is one of the materials most widely used in the road infrastructure industry due to its mechanical and environmental benefits as an asphalt binder modifier. Nonetheless, CR decreases the workability of mixes by increasing the viscosity of the binder, leading to an increase in the production temperatures of asphalt mixes. However, warm mix technologies can reduce the temperature demand associated with these processes. The preceding explains the growing interest in producing rubberised asphalt binders incorporating warm mix asphalt (WMA) additives. In this research, the mechanical and rheological properties of a 60/70 penetration grade asphalt binder modified with CR (at a dosage of 15, 18 and 21% by the wet process) and WMA chemical additives (Evotherm M1 and Iterlow T) were investigated. Laboratory tests included penetration, softening point, rotational viscosity, frequency sweep through dynamic shear rheometer (DSR), and multiple stress creep recovery (MSCR) tests. The results indicate that CR increases the stiffness of the asphalt binder, which is reflected in a lower penetration grade and improved softening point. It also improves its rutting resistance but decreases fatigue performance. Furthermore, it has been shown that under the conditions studied, the higher the CR content, the more elevated the degree of stiffness and performance of the asphalt binder. On the other hand, WMA technology decreases asphalt stiffness and performance at high temperatures.

Rheology of Crumb Rubber-Modified Warm Mix Asphalt (WMA)

“…Sasobit decreased the rotational viscosity of the asphalt binder in its liquid form due to the long hydrocarbon chains in the mix. The rotational viscosity results are supported by findings of previous studies conducted on warm mix additives [14,17,47].…”

“…The decrease in the viscosity when S was added was due to the melting of the Sasobit. Sasobit decreased the rotational vis of the asphalt binder in its liquid form due to the long hydrocarbon chains in the mi rotational viscosity results are supported by findings of previous studies conduct warm mix additives [14,17,47]. At 64 • C, the Sasobit-modified asphalt binders exhibited a doubling and quadrupling of the complex shear modulus value (|G*|) and stiffness for S2 and S4, respectively (Figure 6, Complex Shear Modulus, Phase Angle, and Rutting Parameter Results).…”

“…In addition, when adding WMA and CRM to asphalt mixtures, the rutting resistance improved [45] and moisture damage susceptibility decreased [46]. CRM added to a warm binder prepared with chemical WMA additives weakens its rheological performance [47,48]. Combining the additives with the Polymers 2024, 16, 906 3 of 26 asphalt mixes showed a comparable performance to CRM-modified HMA at lower mixing and compaction temperatures [49].…”

Rheological properties of warm mixed high viscosity asphalt at high and low temperatures

“…Gao ZW [ 16 ] and Zhang JT [ 17 ] studied the effect of warm mixing agent on SBS modified asphalt and found that the viscosity of asphalt was reduced and the high-temperature performance was improved. Akisetty [ 18 , 19 ], Wang HN [ 20 ] and Turbay E [ 21 ] studied the effect of warm mixing agent on the properties of rubber asphalt and found that the permanent deformation of asphalt was reduced. Li ZX [ 22 ] and Yu X [ 23 ] studied the rheological properties of the warm-mixed recycled asphalt, and the results showed that the warm-mixed recycled asphalt exhibited better high-temperature performance.…”

The Microscopic Mechanism and Rheological Properties of SBS-Modified Asphalt with Warm Mixing Fast-Melting

“…In addition to the benefits of lower temperatures, the use of WMA improves workability and increases transportation distances. In addition, reducing the production temperature decreases the energy consumption, which, in turn, reduces production costs [ 20 , 21 ].…”