Recycling of ‘alperujo’ (olive pomace) as a key component in the sintering of lightweight aggregates

Abstract

The current environmental problems that threaten our society can only be mitigated with a radical change in the paradigm of production and consumption. Recycling waste is a key element in this. This work has focused on the valorization of a widely spread agricultural waste: the so-called ‘alperujo’ (olive pomace). For the first time, olive pomace (OP) has been used as a component in the manufacture of lightweight aggregates (LWAs). Mixtures with 0, 1.25, 2.5, 5 and 10 wt% OP have been prepared from three different clays. The research results show that the addition of OP in low proportions (mainly 2.5%) is more positive to achieve aggregate bloating, pore formation and a lighter structure. The high calorific value of OP also helps to reduce the firing temperature significantly, which would result in energy savings. In the same way, bloating would be favored with the increase of the time and the temperature, especially with this last one. The materials obtained have excellent properties. In addition, the study of leachate in the most expanded aggregate shows that the concentration of heavy metals is very low, representing no danger to the environment. According to these findings, the recycling of olive pomace can be an excellent alternative in the manufacture of LWAs.