Influence of chemical treatments of miscanthus stem fragments on polysaccharide release in the presence of cement and on the mechanical properties of bio-based concrete materials

Three types of treatments of miscanthus were performed, alkali, silanization and the combination of both. There is a direct inverse relation between the amount of sugar-containing molecules extracted from miscanthus and the mechanical strength of the concrete blocks. The use of alkali treated stems as fillers increased remarkably the strength of the blocks, and this was even higher when the alkali treated fibers were coated with silica, with a compression strength of 11 MPa compared with an initial 2.2 MPa. The use of alkali-treated stems result in a faster cement hydration, compared to untreated ones suggesting that specific sugars or other components released from the alkali-treated plant may favor cement hydration. A remarkable decrease of the cellulose and xylose content is observed for the miscanthus pieces after being soaked in a cement-water-sand mixture, these two molecules being adsorbed on cement particles.