In fact the aggregates are the main part of all structures in present world ,Also the base material in Road construction is aggregate. there for testing of physical and chemical properties of aggregate (such as Unit Weight ,Absorption and shape ness and etc.) is the base consideration of design of the pavement of the Roads. So we start the testing material by these kind and after some important test of aggregate we will reach to asphalt tests which has sub branches. and finally we have some special test which are very important and ,I must say that some of them is very rare but important test.
when we want to find any definition about size of aggregates ,we face to several definitions ,which varies for propose of use, so we just use the classification of aggregate for Asphalt , there for we use the AASHTO Classification manual Guide , because most of our tests and references in this Web Report is from this guide book. the chart below represent the classification of aggregate according the AASHTO Designation for using for making asphalt mix. ( For more information see M145-91"2000" ) AASHTO Guide Book ((Volume 2)).
| Aggregate type | Rock | Gravel | Coarse Sand | Fine Sand | Silt Clay |
| size | 150-75 mm | 75-2 mm
|
2-0.425 mm | 0.425mm-75µm | <75µm |
Chart 2 : Classification (definition) of soil aggregate mixture for High way Construction Purposes
Below is list of some Useful tests which are necessary for High way Construction Designs and their procedures, each test has a short procedure , an Example and pictures if available, and finally the most and common Errors which may accrue during the test and has affect to final results.