Effect of Biodiesel on Performance of Cold Patch Asphalt Mixtures

In order to reduce the amount of diluent in a diluted asphalt mixture, this study developed a cold patch asphalt (CPA) for repairing pavement potholes by using a mixture of treated biodiesel and diesel as the diluent. The effects of biodiesel on the performance of the cold patch asphalt mixture (CPAM) during the construction process were investigated through Brookfield rotational viscosity tests, adhesion tests, and FTIR (Fourier transform infrared spectroscopy) analyses. At the same time, the effect of biodiesel on the performance of the CPAM was analyzed by combining the strength growth test, rutting test, and water-soaked Marshall test of CPAMs. The test results show that the construction performance of the CPAM can be significantly improved by adding pretreated biodiesel. Under the same amount of diluent, the strength and high-temperature performance of the asphalt mixture diluted with biodiesel were significantly improved compared to that with diesel as the diluent. The optimal high-temperature performance reached 9027 (times/mm), representing an approximate increase of 94.7% compared to 4636 (times/mm) when only diesel was used as the diluent. When the biodiesel content increased from 10% to 40%, the residue stability improved from 85.9% to 91.3%. The corresponding 0.5 h Marshall stability increased from 5.59 kN to 8.1 kN, while the 48 h Marshall stability rose from 4.8 kN to 7.39 kN. All tests met the requirements for hot mix asphalt.