Impact of aggregate coating with a PEC elastomer on properties of lightweight flax shive concrete.

摘要

Lightweight concrete becomes an important subject of research because of its insulating properties. The main objective of this research is to present a process improving the flax shive behaviour in a cement matrix. Flax shives stem from flax culture. It is the major product (50% of biomass weight). To be used as aggregates, shives should have a hydrophobization treatment. The aim of this work is the treatment of shives with a biodegradable elastomer: poly(PEG-co-CA). This elastomer is synthesized by the polycondensation of polyethylenglycol (PEG) and citric acid (CA). After their treatment with PEC elastomer, flax shives show a decrease in water absorption. Then, they are incorporated in a cement matrix. Mechanical properties, thermal properties and behaviour towards water (dimensional variations) of concrete are determined. The shive treatment shows an improvement in compressive and flexural strengths but an increase in thermal conductivity. The extreme dimensional variations (EDVs) and drying shrinkage (DS) decrease also with concrete prepared with treated shives compared to the standard. Overall the lightweight concrete obtained exhibits performances close to those of wood concrete.