Reinforcement of alkali-activated cements based matrices using olive pruning fibres as an alternative to traditional fibres

Recent research has focused on the development of environmentally sustainable materials for replacing conventional Portland cement. Alkali-activated cements, derived from aluminosilicate-rich precursors and an alkaline activator, have been a key area of interest. However, the properties of these materials vary with different precursors, leading to issues like shrinkage and flexural strength deficiencies. To address these challenges, scientists have explored the reinforcement of alkali-activated materials through the incorporation of fibres, both synthetic and natural. This study involved a comparative analysis of various fibres, including synthetic options such as polypropylene and glass fibres, as well as natural fibres like sisal, cellulose, and olive pruning fibres, with some subjected to specific treatments. A consistent 1% wt. fibre content was maintained, as determined optimal in prior research. The matrix was formed using electric arc furnace slag (EAFS) and biomass bottom ash (BBA) as raw materials, while an activator solution of KOH and K2SiO3 was used. Mechanical, physical, and thermal properties were evaluated. The results demonstrated that natural fibres improved flexural strength up to 20% and increased the ductility of the matrix, but the addition of fibres negatively affected physical and thermal properties. Compression strength had different behaviour, improving values in the case of use olive pruning fibres treated by K2SiO3 solution or cellulose commercial fibres, up to 9 and 15%. This research highlights the potential of natural fibres to enhance specific properties of alkali-activated materials.