Evaluation on long-term performance of emulsified asphalt cold recycled mixture incorporating fly ash by mechanistic and microscopic characterization

In this paper, the long-term performance of emulsified asphalt cold recycled mixture (CRME) incorporating fly ash was investigated. The dosages of fly ash included 0.75%, 1.5% and 3.0%, and the long-term service conditions of CRME were simulated by curing in an oven at 60 °C for different ages. Mechanical performance of CRME under different curing ages were obtained through indirect tensile strength (ITS), Marshall stability, low-temperature ITS and freeze-thaw ITS tests, and the microstructures were characterized by optical microscope, X-ray diffraction (XRD) and environmental scanning electron microscopy (ESEM) tests. The results show that, as the curing age increases, the ITS, flow value, and low-temperature indirect tensile strain of CRME with fly ash increase first and then decrease, while the Marshall stability and freeze–thaw ITS ratio (TSR) always show a gradual increase trend. By comparing the CRME with cement, the CRME with fly ash throughout the long-term curing process exhibits the higher ITS and low-temperature anti-cracking performance and the lower high-temperature stability and water stability. Optical microscope, XRD and ESEM analysis indicate that the dissolution of fly ash particles and the demulsification of asphalt emulsion particles occur simultaneously during the curing ages. After a certain curing age, a dense structure composed of asphalt binders, dissolved and undissolved fly ash particles is formed. Also, the fly ash replacing cement in CRME can effectively reduce the energy consumption and carbon emission.

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  • English

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  • Accession Number: 01834646
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jan 26 2022 2:26PM