Mortar Based on Biomass Ashes from Araucanía Region

Abstract

The COMASA S.A. power plant is located near Temuco and burns a high amount of residual biomass produced in the Araucanía region. However, the main problem associated with this plant is the transportation and disposal of fly ash (9 tons per week), a residue generated during the combustion of Boiler I. Currently, fly ashes from Boiler I are transported more than 200 km south, increasing transportation and final disposal costs. In this study, the development of a mortar based on fly ash from the combustion of biomass from COMASA S.A. was analysed at a pre-feasibility level. The experimental procedure consisted of (i) the physicochemical characterization of biomass fly ash, (ii) obtaining different test specimens (mortars) via the addition of different proportions of fly ash (10-35%) to cement, and (iii) obtaining the best specimen by analysing the requirements of mortars for construction purposes (Chilean Standard NCh 1037). The test specimens were subjected to determination of apparent density, compression resistance, water absorption capacity and moisture content. The laboratory results showed that the mortar obtained with the addition of 20% of fly ash has similar physical characteristics to mortars used for building blocks, proving capable of resisting up to 20 MPa. To analyse the viability of the production of construction blocks based on best specimen, market, technical and economic-financial studies were carried out, considering the reuse of at least 60% of the fly ash generated per year. The study concluded that the project was viable, evidencing the potential use of this residue for the manufacture of low-cost blocks, while minimizing the cost associated with residue handling.