REMIBA
USE OF SOLID URBAN WASTE SLAG IN GRANULAR LAYERS FOR ROAD SURFACES
The solid urban waste (SUW) energy recovery plant at the Gipuzkoa Environmental Complex (CMG) generates 40,000 tonnes of incineration slag each year. The usual processes to recover such waste consist of the separation of unwanted materials, mechanical crushing and screening, separation of metals and stabilisation. 70,000 tonnes of the 90,000 tonnes of slag generated annually in the Basque Country are currently destined for landfill. Only 20% of the total (the fraction below 10 mm particle size) is being reused at cement plants.
REMIBA is presented as a continuation of the BIRSU project, financed by Gipuzkoa Provincial Council. The results and experience acquired at REMIBA could also be applied at the Zabalgarbi plant (Bizkaia), which would enable all of this type of waste generated in the Basque Country to be managed in the medium term.
FCC MEDIO AMBIENTE (FCC) is developing REMIBA, with the support of the TECNALIA Technology Centre and the collaboration of GIPUZKOAKO HONDAKINEN KUDEAKETA (GHK) and URBYCOLAN.
DRIVING FACTOR
OBJECTIVES
- Obtain secondary gravel solutions from incineration slag as an alternative to natural quarry aggregates in the production of road surfaces, while also reducing the economic cost of landfill disposal.
- Functional and environmental characterisation of the waste, on a laboratory scale and in a real use environment.
- Study new treatment alternatives in the laboratory in order to proceed, if necessary, to their industrialisation at a later stage.
- Define suitable specifications to serve as a basis for drawing up a future Basque Decree on the recovery of this waste for its inclusion in the Standard for the dimensioning of road surfaces in the Basque Country’s Road Network and to obtain the CE Marking.
RESULTS
- Certain leachates and total contents obtained in the characterisation do not comply with legal limits.
- Development of new waste treatment alternatives: separation of fine fraction and irrigation of 125l/m2.
- Gravel prototypes developed for T2 sections, with percentages between 35% and 75% of slag aggregates.
- Road surface pilot test implemented and experimental validation of final developments in section T3 on the EX2 esplanade on the Eskuzaitzeta Industrial Estate (Donostia-San Sebastián), 4 sections of Type 1.1 road surface with 12 cm of asphalt on gravel prototypes in 2 layers of 25 cm: a control section (0% slag) and 3 sections with 30%, 50% and 70% of slag.
- Emission savings of 9.4 kg CO2 equivalent per tonne of gravel and reduced impact in all categories analysed compared to the use of natural aggregate from quarries, due to the raw material procurement phase and the reduction in transport costs.
- Specifications proposed to the administration with the specifications for the functional and environmental recovery of incineration slag as aggregate for road surface aggregate.
- Submission of the consultation form to EOTA, the European Organisation for Technical Assessment of Construction Products set up under the Construction Products Regulation.
CONCLUSIONS
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Marketing of the proposed solutions will require a new assessment of the leaching results and total content of the material once the Basque Government's Department of the Environment has published the specific environmental decree for the recovery of incineration slag. This reassessment is key to the decision whether or not to implement new treatment processes.
- The low resistance of incineration slag to fragmentation requires it to be mixed with other more resistant materials, which entails additional logistics management. Furthermore, difficulties arose in the compaction of the material during the implementation of the full-scale pilots, requiring longer than usual execution times.
- FCC, GHK and TECNALIA will formally proceed with obtaining the CE marking as a construction material for incineration slag within 1-2 years
ENVIRONMENTAL
TECHNICAL
ECONOMIC
COMMERCIAL
ON THE MARKET
COLLABORATORS
