Abstract

Compaction is an important process for the asphalt mixture service life. A properly compacted mixture is crucial for long-lasting pavement. The objective of this study was to evaluate the influence of asphalt binders on the compactability of the asphalt mixtures by utilizing the concept of the locking point. To achieve this objective, two compaction methods (impact and gyration), different temperatures and asphalt content, and two mixing methods (traditional and alternative) were used. Asphalt binder has significantly influence the properties of asphalt mixtures, even though constitutes only around 5% of the total mass. Two important qualities provided by asphalt binder are adhesion and lubrication. Adhesive properties of asphalt binder provide bonding between aggregates particles after compaction. Lubrication decreases friction forces and allows more workable mixture. In this study, the concept of the locking point was utilized to evaluate the lab compactability of mixtures. The gyratory locking point was defined by analyzing the change of the specimen’s height, and the impact locking point was captured by utilizing an accelerometer. The results indicate that the mixing sequence has a significant influence on the lab compactability of the asphalt mixtures regardless of the compaction method. The alternative mixing alters traditional mixing and permits improvement in the film thickness of coarse aggregates, which may affect the homogeneity of the asphalt mixture. The mixing sequence has more influence on the mixtures with larger stones since it is more challenging to get an adequate coating on the largest particles, and the mixing sequence affects mixing efficiency. On average, alternative mixing permitted around 50% faster coating of aggregate particles than traditional blending. The lubricative properties of asphalt binder increase with decreasing viscosity and the lab compactability of the asphalt mixture is improved by higher asphalt content.

Authors (6)