Case Study #278
1. Headline: Internal recycling in a French concrete plant
reduces effluents.
2. Background: The Garon Company set up a plant
manufacturing ready-to-use concrete, in Nanterre in 1991.
In 1992, the company set up a water and granulates
recirculation equipment. This case study was carried out
in 1992. Average production of the plant : 400 m3/day.
Mixing water consumption : 200 l/m3. Rinsing water
consumption : 1 m3 by mixing unit. Washing water for the
plant : 50 m3/day.
3. Cleaner Production Principle: New technology
4. Description of Cleaner Production Application:
Information about the process and wastes
The plant uses 145 m3 of water a day, withdrawn from the
river. The water used for washing was settled in tanks (60
m3 of capacity), then stored in underground storage (about
75 m3). Excess water was discharged to the river.
The returns of concrete were discharged from the lorries
down to an area, waiting for a transfer to a quarry owned
by the company.
A water and granulates recirculation plant was set up. A
screw carries up the granulates washed by a downward water
flow which carries down the fine particles of cement.
Water loaded with fines is stored in the underground tank,
equipped with two stirring devices in order to avoid
settling. These loaded waters are recirculated for
producing concrete, washing lorries, or in the granulates
washing screw. The washed granulates are used in concrete.
Material / energy balance and substitution: Withdrawal
from the river is reduced from 145 to 80 m3/day.
5. Economics: Cost of direct investment: Total : 758 000 FF
(1992), settling tanks and feeding system of the screw
represents an amount of about 1 000 000 FF.
6. Advantages: Decrease by 50 % in the S.S. discharges.
Recirculation of sand and granulates.
No more discharges of returned concrete.
The settling tank must be large enough and a spare tank is
necessary in order to face exceptional peaks of returned
concrete or a failure of the equipment.
Technical normative may stand in the way of using concrete
which blend recycled fines or granulates. Sand and gravel,
in particular, are not separated by this plant.
It is necessary to give main instructions to all staff,
internal and external, about making good use of the
equipment. A continuous supervision of the working is
essential, night and day.
7. Constraints: No information provided.
8. Contacts:
Agence de l'Eau Seine-Normandie
Mlle MATHIEU
TEL: 33 41.20.16.23
M. BERNARD
Redland Granulats
TEL: 33 64.73.41.00
Centrale ... bÆton de Nanterre
Z.I. du Port
Rue Lavoisier
92000 NANTERRE - France
TEL: 33 64.73.41.00
FAX: 33 64.68.05.46
M. Maton
M. Chatenet
Office International de l'Eau
Direction de la Formation et des Etudes
rue Edouard Chamberland
87065 Limoges Cedex, France
TEL: 33 55114770
FAX: 33 55777115
9. Keywords: France, concrete, recycling, new technology,
recirculation, water saving
10. This case study was submitted to UNEP IE in 1994 by the
French Office International de l'Eau. It has not undergone
a formal technical review.