The Effects of Bag House Fines and Incomplete Combustion Products in a Drum Drier on the Characteristics of Asphalt Paving Mixtures, Phase II

An extensive laboratory study of the asphalt paving mixtures containing baghouse fines has been conducted through seven sets of experimental designs to characterize the performance of pavement. Marshall size specimens of asphalt paving mixtures with different kinds and amounts of baghouse fines were fabricated using the gyratory testing machine. The following techniques were used to evaluate the influence of the various variables upon mechanical properties such as: gyratory parameters, resilient modulus, indirect tensile strength, indirect creep, and Hveem stability tests to evaluate their mechanical properties. In addition, in the asphalt paving mixtures, asphalt cement was replaced with baghouse fines in order to maintain a constant volume of asphalt cement plus baghouse fines. The evaluation was conducted under the simulation of plant aging, evironmental aging, moisture damage, and traffic densification. The gyratory stability index and gyratory elasto-plastic index can be used to determine the effect of baghouse fines on asphalt paving mixtures during specimen fabrication. The resilient modulus, indirect tensile strength, and Hveem stability decrease significantly with higher amounts of baghouse fines. Artifical aging processes to simulate pavement performance caused an increase in resilient modulus and the indirect tensile strength as well as a reduction in failure tensile strain. The effect of water sensitivity of asphalt paving mixture decreased with increasing amount of asphalt cement or with decreasing of baghouse fines/asphalt cement ratio. Densification of asphalt paving mixtures produces higher indirect tensile strength, but it also decreased the resilient modulus. The resilient modulus value was insensitive to the gradation of baghouse fines of mineral fillers, but the indirect tensile strength increased significantly with finer fines or fillers