Open AccessEffect of Compaction Methods on the Morphology of Aggregates in Hot Mix Asphalt
Author(s) -
Mohammed Abed,
Alaa H. Abed
Publication year - 2020
Publication title -
iop conference series. materials science and engineering
Language(s) - English
Resource type - Journals
eISSN - 1757-899X
pISSN - 1757-8981
DOI - 10.1088/1757-899x/671/1/012119
Subject(s) - compaction , asphalt , aggregate (composite) , interlocking , randomness , geotechnical engineering , asphalt pavement , hammer , axle , gradation , materials science , engineering , structural engineering , composite material , computer science , mathematics , statistics , artificial intelligence
Hot mix asphalt plays a very important function in determining a pavement’s capacity with regard to major failures, such as fatigue, permanent deformation, and thermal-associated cracking. Hot mix asphalt’s behaviour is affected by the mechanistic attributes and shape of its constituent aggregates, alongside the geometric properties of those aggregates such as position and orientation. This paper focused on characterising the aggregates used in producing hot mix asphalt and their allocation within such asphalt mixes using digital image processing (DIP) methods. Additional laboratory tests were also performed in order to match compaction methods used in the laboratory with those occurring in the field. The results provided evidence that this methodology offers simpler and faster ways to provide a full indication of the behaviour of aggregates during compaction and to determine their tendency to randomise throughout the compaction process. ImageJ Fiji software was found to be competent to characterise aggregates’ constituent forms and orientations; randomness, represented by vector magnitude, is determined in an aggregate directional array as an orientation factor (Δ) and used as a reference for better interlocking where heavy compaction is used. This factor ranges from 0 to 100%, where 0% indicates completely random particles and 100% indicates that particles are exactly within a single array. Mixes compacted with a Superpave gyratory compactor (SGC) and roller compactor had aggregate particles with relatively higher numbers of contact points and randomness than those mixes compacted using a Marshall Hammer. The results also showed that vector magnitude is an approach to determining field compaction, with results of 82.6, 67.43, and 90.7% for SGC, Marshall Hammer, and roller compacter compaction, respectively. This makes it clear that SGC and roller compaction are the nearest types of compaction to those used the field. DIP also showed that the percentage of contact points in various types of compaction were 63.6 and 92.9% for Marshall and roller compacters, respectively, while field core was found to have 88.4% contact points when produced by SGC.