Construction and works

Ihobe Eusko Jaurlaritza

BITAR

BITUMINOUS MIXTURES OBTAINED FROM THE RECOVERY OF MOULDING SAND

Finding a solution for foundry sand waste from the metallurgical industry, which is mainly destined for landfill, remains an important need for Basque industry. One is the functional and environmental suitability of these moulding sands for use as fine aggregate in bituminous mixtures for road surfaces. The proposal is based on previous pilot studies, such as the PISSAM project (Innovative cement-based products from the recovery of iron and steel by-products from moulding sands) and promising small preliminary tests of bituminous mixtures with moulding sands and iron and steel aggregate carried out by the developer in order to identify the potential risks for placing these recycled products on the market on the basis of the knowledge acquired.

ASFALTADOS OLARRA, a company specialising in the asphalting sector, has led BITAR, in which it has worked with the TECNALIA Technology Centre

ASFALTADOS OLARRA
OBJECTIVES
  • Study the feasibility of a new recovery solution for moulding sands (green or chemical) by developing new asphalt mixes that also incorporate steel aggregate.
  • Identify the most suitable conditions of use for milling and steel aggregate mix as a substitute aggregate for natural aggregate in bituminous concrete mixes and discontinuous mixes.
  • Reduce the environmental impact associated with the use of non-renewable resources.
  • Define suitable specifications that serve, on the one hand, as a basis for starting work on the voluntary CE marking of this aggregate mix for use in bituminous concrete mixes and discontinuous mixes, and, on the other hand, as a reference for its inclusion in the Standard for the Dimensioning of Road Surfaces in the Basque Country's Road Network.
RESULTS
  • Compliance of the proposed mixtures with the requirements set out in the PG3 specifications .
  • The physical-mechanical and environmental properties of the waste studied do not prevent their use for the manufacture of bituminous concrete mixes and discontinuous mixtures.
  • BITAR technical specification document for the recovery as a filler aggregate for bituminous concrete mixes and discontinuous mixes.
  • Submission of the consultation form to EOTA, the European Organisation for Technical Assessment of Construction Products for construction products set up under the Construction Products Regulation.
  • Savings of 36 kg of CO2 equivalent emissions per tonne of asphalt mixes by replacing natural aggregates from quarries with the recycled aggregates proposed in BITAR.
CONCLUSIONS
  • The major environmental advantages of using moulding sands and steel aggregates as raw materials for the manufacture of bituminous mixtures occur at the raw material procurement and transport stages.
  • The waste used and recovered is initially suitable in the proposed percentages for use in both bituminous concrete mixes and discontinuous mixes for structural surfaces.
  • ASFALTADOS OLARRA has established contacts with agents interested in the solutions proposed by BITAR to ensure the supply of moulding sand and steel aggregate in the future. 

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