Enabling pseudo-ductility in geopolymer based glass-ceramics matrix composites by slurry dilution

Abstract : Carbon fibre reinforced composites with matrix consisting of porous glass-ceramics obtained by high temperature heat-treatment of geopolymer based material are studied. The matrix is obtained from a slurry. Several composites have been manufactured by in-laboratory stratification of pre-impregnated plies with slurries diluted at various rates. Slurry dilution changes the porosity and leads to pseudo-ductile behaviour of the composite. Dilution implies a drop of non-linearity stress threshold together with a slower decrease of the strength. An optimal dilution rate is evidenced, which exhibits high strength but lower non-linearity stress threshold, and then, a significant failure strain. The optimized prepreg material is compared with a reference composite processed by an industrial prepreg process. The origin of the pseudo-ductility is related to decohesion at the interface between tows and inter-tow matrix. RTM also provides a pseudo-ductile composite but with very low non-linearity stress threshold, in relation to poorly impregnated tows.