A comprehensive particle packing-based design of bituminous mixtures and its mechanical characterisation

ABSTRACT

The one-to-one contact of coarse aggregate is considered to be the main source for the resistance to permanent deformation and to an extent to fatigue damage. Therefore, it is imperative that the mixture is placed with an interlocked coarse-aggregate skeleton. The conventional mix design approaches generally follow dense graded aggregate gradations, which target for maximum density without accounting the one-to-one contact of coarse aggregates. The current study describes an approach for analysing particle packing in bituminous mixtures based on the compressible packing model (CPM), which provides an analytical expression for the estimation of aggregate packing density. Three mixtures with chosen particle packing indicators and a conventional dense graded mixture are subjected to repeated load haversine compression at temperatures between 25${}^{\circ }$ and 55${}^{\circ }$ for a frequency range of 0.01–25 Hz. Selection of binder content is carried out based on equivalent compactability criteria. The link between the packing density of aggregate gradation, dynamic modulus, phase angle, master curve parameters, and relaxation spectrum is evaluated in this study. It is observed that dynamic modulus at high temperature, and low frequency, the phase angle, master curve parameters and the relaxation spectrum exhibit sensitivity to the variation in aggregate gradation.

KEYWORDS:

• Compressible packing model
• packing density
• interactions
• equivalent compactability
• master curve
• relaxation spectrum

Disclosure statement

No potential conflict of interest was reported by the authors.