Title

Preparation and Performance Evaluation on Polyurethane Composite Modified Asphalt

Document Type

Article

Publication Date

2021

Department

Department of Civil, Environmental, and Geospatial Engineering

Abstract

The objective of this study was to improve the properties of polyurethane (PU) modified asphalt, which can be used in road engineering. The PU composite modified asphalt was prepared using PU, rock asphalt (RA), and base asphalt (BA) through a self-developed laboratory process, and subsequently, the suitability of the preparation process parameters was discussed. The composition of PU and RA was optimized by penetration, softening point, ductility, and rotational viscosity tests. The temperature sensitivity of the PU composite modified asphalt was analyzed based on the colloid theory. The rheological properties of the PU composite modified asphalt were investigated by dynamic shear rheology and bending beam rheology tests, also the multiple stress creep recovery test was performed to evaluate the permanent deformation resistance. Next, the Performance Grade temperature of the composite modified asphalt was determined. Scanning electron microscope was used to observe the internal microstructure of the PU composite modified asphalt. The key chemical reaction between PU and asphalt was explored by an infrared spectroscopy test. The results show that the penetration, softening point, and ductility of the PU composite modified asphalt improve by 42%, 4%, and 19%, respectively, with an increase in the PU content from 1% to 5%, and when 5% RA was used. The softening point of the composite modified asphalt containing 5% PU improves by 17% with an increase in the RA content from 5% to 15%, whereas penetration and ductility decrease by 64% and 138%, respectively. The PG high temperature grade of both PU composite modified asphalt with 5% PU and 15% RA and 3% PU and 15% RA can reach 82℃. The PG temperature grade of PU composite modified asphalt with 5% PU and 5% RA was -22℃, indicating that the use of PU can improve the low temperature rheological properties, and the introduction of RA can increase the high temperature rheological properties with regard to BA. BA, PU, and RA perform a preferable compatibility, proving the feasibility of the proposed preparation method. Both obvious chemical reactions were exposed in the PU composite modified asphalt, namely, the addition reaction between the isocyanate and aromatic compounds in BA and the unsaturated bond in PU crosslinked with the S-S bond in BA. Additionally, the resistance to low temperature deformation is due to the crosslinked network structure that is formed.

Publication Title

Zhongguo Gonglu Xuebao/China Journal of Highway and Transport

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