MECHANICAL CHARACTERIZATION OF CONCRETE WITH RECYCLED AGGREGATES FROM COAL MINING WASTES

Nowadays, recycling is one of the most important topics regarding waste in several different fields, especially with reference to sustainable development goals, as also recognized since 1992 in the United Nations Earth Summit. Nevertheless, the world production of waste grows every year, and energy production is responsible for a great part of this residue, especially considering exploration of coal mines. Generally, waste coming from this activity is simply stockpiled, but a different way to use these materials can be studied, exploiting them as secondary raw materials for different processes, in accordance with the circular economy approach. The production of concrete employing coal mining waste geomaterials (CMWGs) as recycled aggregates has been recently investigated: a sustainable material may be produced, avoiding the disposal problems. In this paper the results are shown of an experimental campaign, performed in the framework of the Project MINRESCUE, funded by the European Commission in the framework of the Research Fund for Coal and Steel (RFCS 2014-2020 GA 899518). Reuse of coal wastes from different mine sites as partial replacement of natural fine and coarse aggregates in concrete has been investigated, considering the following replacement volume fractions: 25% of fine aggregates, 25% of coarse aggregates and 13% each of both fine and coarse aggregates. Mechanical properties including compression and flexural strength, fracture energy, elastic modulus and shrinkage have been measured. Results highlight that a manageable variation of the mechanical parameters with respect to the reference ones has been obtained, with reduction between 6% and 32% in cubic and cylindrical compression strength and in elastic modulus values. Similar results have been obtained for fracture energy. Also shrinkage tests have shown good results, thus validating the possibility to use pursue this path as a solution for the coal mining wastes disposal problem.