The application of baghouse fines in Taiwan

Strict environmental regulations in Taiwan require baghouse fines (BHFs) to be collected during hot mix asphalt production. In an attempt to utilize this byproduct, baghouse fines have been incorporated into asphalt concrete mixtures, which were applied to county roads and other light traffic roads despite a lack of research. This study examines 14 types of fines, including 9 baghouse fines, 2 mineral fillers, fly ash, cement, and lime. The baghouse fines that were collected from asphalt plants in different regions represent generic fine types from various aggregate sources. Comprehensive laboratory tests were performed to determine the impact of different types and quantities of fines on mechanical properties and moisture resistance of the asphalt concrete mixtures. Resulting data indicates that the amount of stiffening is not uniquely related to fines and that gradation and miner properties alone cannot explain the stiffening effect of fines. Increased stiffness, due to the addition of the filler, is represented by an increase in the softening point, in viscosity, and in complex shear modulus (G*), as well as a decrease in penetration. The stiffening effects of baghouse fines vary greatly. Performance in terms of stiffness and resistance to moisture related damage for asphalt binders with fines (baghouse fines, lime, cement, mineral filler) was better than AC20 asphalt without fines. The best performer among baghouse fines was A4 (Group 1), with the least amount of SiO2. The authors believe that Group 1 baghouse fines, including A1, A2, A3, A4 and A9, are superior to mineral filler and can be used on highways or expressways with heavy traffic. Groups 2 (A6) and Group 3 (A5, A7, A8) baghouse fines should be used on light traffic roads, such as county roads. To increase moisture resistance, the addition of 1–2% lime should be considered.