Study on the Aging Resistance of Polyurethane Precursor Modified Bitumen and its Mechanism

Abstract

As an environmentally friendly alternative for the production of high-performance modified asphalt by chemical reactions, a liquid-state polyurethane-precursor-based reactive modifier (PRM) was developed and employed in the asphalt modification. In contrast to the traditional solid bitumen modifier, for example, rubber and thermoplastic elastomers, the PRM as a liquid modifier has more significant advantages in reducing energy consumption and improving asphalt performance, which has attracted widespread attention. However, the aging resistance and its mechanism are not clear. In view of this, the aging performance of two PRM-modified bitumen (PRM-70 and PRM-90), under the short-term thermo-oxidative aging, long-term thermo-oxidative aging, and ultraviolet (UV) aging conditions, was investigated through chemical and mechanical methods. The results show that the PRM-90 is more susceptible to the thermos-oxidative aging and UV aging. The use of low-penetration-grade bitumen and ensuring an adequate reaction are beneficial to enhance the aging resistance of PRM-modified bitumen. The impact of aging on high-temperature performance of PRM-modified bitumen is great, followed by the low-temperature performance and the anti-fatigue performance. The mechanic-relevant rheological aging index (RAI) and fracture energy index (FEI) are recommended to evaluate aging properties for PRM-modified bitumen. This study not only provides support for further research on the relationship between the aging properties and mechanical performance of PRM-modified bitumen, but also provides a reference for conducting mechanism analysis.

Rheological properties and aging resistance of self‐healing polyurea elastomer modified asphalt

“…This result may be related to the poor UV aging resistance of polyurethane materials, and this impact is more reflected in the high‐temperature modulus of asphalt binder 52 . The chain breaking effect of ultraviolet radiation on polyurethane materials may be the main reason for the increase in high‐temperature modulus of PUA modified asphalt after UV aging 53 . Chain breakage causes fragmentation of PUA molecules, which weakens the toughening effect of soft segment molecular chains and increases elasticity 54 .…”

“…The chain breaking effect of ultraviolet radiation on polyurethane materials may be the main reason for the increase in high-temperature modulus of PUA modified asphalt after UV aging. 53 Chain breakage causes fragmentation of PUA molecules, which weakens the toughening effect of soft segment molecular chains and increases elasticity. 54 At the same time, the adhesive composition of the matrix asphalt will increase in high-temperature environments.…”

Effect of hydrated lime and other mineral fillers on stiffening and oxidative ageing in bitumen mastic

“…Further, the process of ageing involves two kinds of mechanism; the first one is the irreversible one recognised by the chemical changes in the bituminous binder, which affect the rheology of the bitumen. This process includes oxidation, evaporation of volatile components and escaping of oily constituents from the bituminous binder into the aggregate [3]. The other mechanism is the reversible one, known as physical hardening.…”