Preparation and technical performance evaluation of cigarette butt fiber-modified asphalt

Cigarette butts (CBs) are a very harmful solid waste and their main component is cellulose acetate fiber (CAF), which has potential application for improving the technical properties of asphalt. To analyse the effect and the optimal dosage of cigarette butt fiber (CBF) on the improvement of asphalt technical performance, collected CBs were sorted and flocculated to obtain 1–2 mm fibers, which were incorporated into 70# and 90# base asphalt at controlled dosages (0.25%–1.00% by weight) to prepare CBF-modified asphalt. Fluorescence microscopy, conventional asphalt tests, and a series of rheological measurements were used to characterize the microstructure and high-/low-temperature performance of the CBF-modified asphalt. Results show that CBF formed an effective network within the asphalt matrix, leading to enhanced high-temperature performance in both base asphalts. This was reflected in improved rutting resistance and elastic recovery. However, low-temperature crack resistance deteriorates, plausibly due to the weak polarity of CAF and variability in fiber morphology, which may act as stress concentrators. Based on a comprehensive evaluation of the technical performance, for 70# and 90# asphalt, the optimal dosage of CBF is recommended for 0.75% by weight. The use of CBF as an asphalt modifier not only achieves the recycling of CBs but also improves the technical performance of asphalt, demonstrating promising application prospects.