One of the most important steps in process of asphalt recycling is RAP accumulation and management. Proper RAP management practices should always be part of asphalt recycling operations. The quality of recycled asphalt mix with high RAP percentage depends on proper RAP management methods. To achieve the realistic goals of producing recycled asphalt from RAP (in high percentage), four basic steps can be recognized:
Collection and accumulation of available RAP in a specified period of time
Summary report of the types of recycled asphalts produced using RAP based on the percentage of RAP used and the type of asphalt and the relevant project in the previous period
Determine and estimate the maximum amount of usable RAP
Quantitative comparison of available RAP with required RAP
1) RAP Crushing and Fractioning
How to prepare and fractioning of RAP is essential and plays a decisive role in the production and quality of final recycled asphalt. The crushing and fractioning process includes the following steps:
1.1 Mixing: mixing and homogenizing the composite RAP stockpile
1.2 Crushing: Crushing over size RAP and milled asphalt with a suitable crusher for preparing RAP
1.3 Fractioning: Screening RAP with multi-layer screen
1.4 Re-crushing: Re-shredding the large chip left on the screen and turning it into a smaller size
1.5 Final separated stockpile: accumulation of fractioned RAP separately
2) Identification important RAP parameters
General characteristics of the RAP play an important role in the asphalt recycling process. Based on scientific experience and theoretical achievements the following important parameters of the RAP can be physically specified, these parameters can be identified during the sampling process of RAP and related tests.
2-1) General characteristic include:
Determine the percentage of bitumen in the RAP
Determine the granulation diagram of the RAP
Determine the moisture content in the RAP
2-2) Determine the RAP specific gravity
2-3) Determine the bitumen characteristics of the RAP (if %RAP >%25)
