Autogenous Healing of Fiber/Matrix Interface and Its enhancement

Fiber-reinforced cementitious composites (FRCC) represent a large group highperformance concrete for buildings and constructions. In this paper, the long ignored autogenous healing at debonded micro fiber/cement matrix interface (~1 μm crack) is demonstrated for the first time. Class F fly ash, a common Portland cement replacement that is rich in silicate, is engaged to promote interfacial healing. Single micro fiber pullout tests and microstructural characterization show that the presumed fiber/matrix healing indeed takes place and causes significant increase of the mechanical bond between fiber and matrix; additional silicate-rich fly ash greatly improves the healing efficiency. Uniaxial tensile test to the fiber-bridging indicates that the fiber/matrix interfacial healing can enhance the tensile strength of FRCC.