Performance characteristics of coal fly ash and wood ash-modified asphalt binder

Coal fly ash and wood ash were added singly to asphalt mixes as partial replacements of the asphalt cement. Mechanical property testing and cost analysis were carried out with the following percentages: 0, 10, 15, 20, and 25. The objective of the investigation was to determine the changes in mechanical properties and cost-effectiveness of ash modification. The softening point, penetration, creep displacement, and modulus of elasticity indicated stiffening of the mix with increased ash proportion. The indirect tensile and compression strengths reached peak values for the 10 and 15% mixes. The Marshall stability, the bulk density, and the maximum density, decreased with ash addition. The cost analysis indicated a saving of 6% for ash replacement of 15%. Therefore, the replacement of 10 to 15% of asphalt cement is an excellent solution to decrease the mix costs and to reduce the amount of ash in landfills without compromising the mechanical properties of the mix.