Recycling of manganese gangue materials from waste-dumps in the Iberian Pyrite Belt – Application as filler for concrete production

This study proposes an application of mine wastes from the exploitation of manganese ores deposits in the Iberian Pyrite Belt (SW Spain) in the civil engineering and construction sectors. The powdered waste rocks were used as filler in concrete, replacing part of the fine aggregate, in order to develop a new mixture. A comparative study on the performance of the concrete was carried out with control samples and with this new mixture. The experimental tests indicate the fitness of the new material for the purposed application, namely regarding resistance to compression. The new mix reached higher compressive resistance (56.44 MPa), comparatively with the conventional concrete (maximum at 41.03 MPa). The experimental tests demonstrate that: (i) gangue material give better properties to the concrete, (ii) it allows the replacement of concrete as filler in bituminous concretes, and (iii) it allows the reduction of the amount of cement used in “in situ” safety barriers in road construction. In addition, the recycle of the presently unwanted gangue will contribute to eliminate the environmental degradation promoted by the numerous waste-dumps in the Pyrite Belt. Consequently it results in lower environmental remediation costs of mine sites. Simultaneously, it would reduce the impact of new quarries, since it contributes to save stony raw materials. Moreover, extracting these valuable resources from the mine wastes stream will represent an industrial opportunity with financial returns, and, at the same time, improving environmental outcomes.