Recycling Equipment in Asphalt Production Plants
By the “Equipment Commission” of the French Institute of Roads, Streets and Infrastructure for Mobility/IDDRIM.
The IDDRIM Recycling Standing Group is drawing up a guide to high-rate recycling in hot-mix asphalt production plants. The Equipment Commission1of the IDDRIM Approval Operational Committee has been tasked with writing the “equipment” section.
This article is a summary of Chapter 3 written by the Equipment Commission, the main outline of which was pre-sented by Jacques Bonvallet at the IDDRIM congress in Lyon in September. The whole guide will soon be available on IDDRIM’s website. The subjects on the production of asphalt aggregates, formulation, work site management, fields of use or administrative aspects are tackled by the Standing Group.
There are over 300, mainly stationary, recycling plants in France.
- The mean potential recycling rate overall is 35% for 3% humidity.
- 50% of plants operate continuously and 50% in batches.
- Those plants able to recycle at a rate of more than 60% account for less than 2% overall.
- The most common technique at present is the recycling ring.
The guide’s technical datasheets are universal and therefore valid whatever the country. Only the distribution of preferred techniques used will change. For example, batch-mix plants are dominant in Germany and/or Holland.
The IDDRIM Equipment Commission brings together experts from 3 colleges, Administration (currently the BLOIS Road Building Equipment Test Centre/SEMR), road firms (members of the French Road Industry Unions Association/USSIRF) and French Union of Building Equipment for Steel Infrastructure and Handling/CISMA manufacturers (one permanent member and two other members, FAYAT and AMMANN).
Reminder of the main hypotheses adopted
- The initial temperature of aggregates is 10°C.
- The final temperature of asphalt is 150°C*.
- The residual water content of asphalt is less than 0.5%.
- Rates are calculated at sea level.
- The temperature of reclaimed materials (RAP) after direct heating in a parallel- flow dryer drum is between 120 and 130°C.
- The RAP is uniform, in keeping with standard NF EN 13108-8.