Evaluation of the Specific Surface Method as a Tool to Determine the Binder Content of Fine-Aggregate Matrices

Abstract

Studies have shown that fine-aggregate matrices (FAM) are a good tool to assess fatigue cracking and moisture damage of hot-mix asphalt (HMA) mixtures. However, there is no consensus on the design method to produce FAMs that represent precisely the fine fraction of the HMA mixture. This study evaluates two design methods to determine the FAM binder content: one based on asphalt extraction by ignition and one based on the mineral aggregate specific surface area. The results led to the proposal of refinements in both methods regarding the crystallization water of the mineral aggregates, the use of more precise methods such as laser diffraction to estimate the filler specific surface area, and the estimation of the richness modulus of the FAM obtained from the full HMA mixture. A relationship between the richness modulus of the HMA mixture and the FAM binder content was established, which turns the method based on the specific surface area of fine aggregates into a viable and promising tool to estimate the FAM binder content.