Innovation Series: Advanced Science (ISSN 2938-9933, CNKI Indexed)

Research on Recycling and Utilization Technology of Old Asphalt Mixtures from Road Surfaces and Their Performance

Yan Zhang^*

Dalian University of Engineering, Dalian 116600, China

Corresponding Author: Yan Zhang

Abstract: To address the issue of recycling and reusing the waste asphalt mixtures (RAP) generated from highway maintenance, a systematic study was conducted on the mix design and performance regulation of hot recycling, cold recycling, and semi-rigid base recycling mixtures. The optimal scheme for hot recycling was 60% RAP content, 12% recycling agent content, and 1.87% new asphalt content, with a dynamic stability of 4866 times/mm and a freeze-thaw splitting strength ratio of 107.1%, and a -10℃ flexural strain of 2131.5 με. For cold recycling, the reasonable scheme was 90% RAP content, 4.3% emulsified asphalt, and 1.5% cement, with a dynamic stability of 2425 times/mm and a freeze-thaw splitting strength ratio of 82%. For semi-rigid base RAP, the reasonable content was 30% to 50%, with a cement content of 4.5% to 5.0%, and the 7-day unconfined compressive strength met the requirement of not less than 3.5 MPa. Fine separation of RAP can reduce the grading variation coefficient to 6.2% and control the false particle content within 10%. Intelligent construction and full-process quality monitoring effectively guarantee the quality of recycled pavement. The engineering application saves material costs by approximately 20%, shortens the construction period by about 30%, and has significant economic and ecological benefits.

Keywords: Waste asphalt mixture; Hot recycling; Cold recycling; Mix design; Road performance; RAP content

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