Work package 4 (WP4) – New methods for IBA fine fraction utilization in construction industry

More than 150 million tons of municipal solid waste are incinerated each year in Europe, producing over 20 million tons of Waste-to-Energy-Bottom Ash (IBA). The past years around 50 wt% of the total IBA produced have been used in road construction as a fill material, mainly in embankments. The remainder is disposed in landfill, due to lack of outlet. On the other hand, properties of the fine fraction of IBA are similar to raw materials used in mortars. Consequently, it is of high interest to focused on the use of IBA as secondary raw material in construction, namely in concrete-based products. Nevertheless, due to the important amount of metals contained in IBA, and especially metallic aluminium, previous studies describe the presence of swelling phenomena induced by the production of hydrogen during the oxidation of metallic aluminium. The purpose of Refina WP4 is to take advantage of this reaction, by incorporating IBA as aerating agent in aerated concrete (AC). AC is a very porous material (density between 350 and 800 kg.m-3), has a low thermal conductivity (≈0.15 W.m-1.K-1) and moderate mechanical strength (>4 MPa). Due to these properties, it is easier to handle than standard concrete and it is used as insulating material.

Our methodology is based on three steps: (1) pre-tests (on small samples of binder-water-IBA), (2) mortars (containing binder-water-sand-IBA) and (3) concrete (binder-water-aggregates-IBA) (see figure below). For each step, the performances of normalised formulations for aerated products are compared to formulations including IBA. The performances of tested formulations are compared based on the following tests: mechanical resistance, density, slump test, thermal conductivity, porosity. The environmental performances of final products are also evaluated by leaching test.