Improved bonding of carbon fiber reinforced cement composites by mineral particle coating

Abstract

The low penetrability of cement product into the interior of multifilament yarns hinders the utilization of textile reinforced concrete (TRC). This inferior fiber-matrix bond often leads to premature failure. Therefore, improved bonding of such textile reinforced composite is much needed. This study focuses on the improvement of multifilament carbon yarns’ bond to cement matrix by mineral particle coatings. A carbon multi-filament was impregnated by micro-sized alumosilicate, nano- and micro-sized silica. The penetrability of the particles into the multifilament was characterized and the effects of the coatings on the fiber/matrix bond were compared to an epoxy-polymer coated-carbon multifilament. The micro-sized silica and alumosilicate coatings coated the yarn efficiently and enhanced both pull-out strength and toughness as compared to both nano-silica and epoxy coatings. This was mainly attributed to superior bonding due to a postulated pozzolanic effect. Contrarily, the nano-silica failed to show the same beneficial effects due to extensive agglomeration. It is concluded that coating of carbon multifilament with mineral fillers should be highly considered for TRC. However, the filler has to be thoroughly deagglomerated prior to the coating step.