Exploration into Designing Asphalt Mixtures for Macrotexture

Macrotexture is pivotal in pavement engineering, greatly impacting skid resistance, drainage, noise, longevity, maintenance, and ride comfort. Adequate macrotexture enhances road safety by improving the friction and reducing the risk of crashes. The recent focus on the durability of dense-graded mixes has raised concerns about potential compromises to macrotexture. Macrotexture involves the presence of voids and the distribution of aggregates on the surface of the mix. It aids drainage and boosts friction, crucial at high speeds for necessary hysteresis-induced friction; the Federal Highway Administration (FHWA) is researching a macrotexture testing procedure that can be used for mix design, verification, and field use. These efforts aim to strike a balance between enhancing pavement durability and maintaining adequate macrotexture for optimal performance. This evaluation compares field macrotexture measurements to laboratory gyratory compacted asphalt specimens. The results show good correlation between gyratory specimens at Ndesign and field measurements taken on a new pavement. By comparing field and laboratory macrotexture measurements, the FHWA aims to advance the understanding of macrotexture performance across mix types and optimize its incorporation into mix design, mix verification, and field verification practices. This research seeks to strike a balance between improving pavement durability and preserving adequate macrotexture for optimal pavement performance.