Asphalt is defined as a mixture of inert mineral matter, such as aggregate, mineral filler and bituminous binder in predetermined proportions. These materials are known as Road Stone Aggregate.
Different types of Asphalt:
Continuously Graded Asphalt – Mechanically Mixed Asphalt
Aggregate and filler are distributed in size, from fine to coarse fractions within a specified smooth grading envelope.
- Slurry Seal.
- Large Aggregate Mixes for Bases and Surfaces (LAMBS)
- Asphalt Continuously Graded medium (ACGM)
- Asphalt Continuously Graded Fine (ACGF)
Gap Graded and Semi-gap Graded Asphalts – Mechanically Mixed Asphalt
Asphalts from which some intermediate sizes are excluded to comply with a stepped grading envelope (19mm or 26mm Max aggregate size)
Open Graded Asphalts (Aggregate skeleton mixes) – Constituted Mechanically Mixed Asphalt
Normally a single-sized crushed aggregate, this asphalt gives a rough surface texture in the compacted state.
High dust content due to the single-size of either 13.2mm of 9.5mm mixed with a-3mm sand.
Some names in the industry include:
- Stone Mastic Asphalt (SMA)
- Nova chip
- Bitumen Rubber Asphalt semi-open (BRASO)
- Bitumen Rubber Asphalt Course (BRAC)
Because of the importance of the aggregate in the mix, it is important to fully understand the effects of its properties. It is advised that the client conducts the necessary tests to produce and maintain a mix meeting the design requirements.