Secondary hydration is the main driving force of autogenous self-healing and directly impacts the closure of cracks in damaged cementitious materials . In fiber-reinforced cement composites , secondary hydration also dominates the regeneration of the fiber-matrix interface during the self-healing processes. As an important factor influencing the cement hydration , silica fume (SF) addition can be crucial to the self-healing performance of cementitious materials and composites. In this paper, the effect of SF on the autogenous self-healing of ultra-high-performance fiber-reinforced concrete was investigated. With a ≥20% SF addition, the secondary hydration the cement matrix adjacent to the cracks was accelerated. The dissolution of amorphous silica and the formation of Si-containing healing phases was observed. These effects predominated the closure of the mouth and the inner part of the cracks. SF addition also enhanced the regeneration of fiber-matrix interface by promoting the growth of self-healing products in these areas. The closure of cracks and the regeneration of fiber-matrix interface are both responsible for the restoration of flexural properties.
Yuxin He,Qiuyu Chen,Song Yang,Chang Lu,Mengting Feng,Yuanli Jiang,Guoxi Cao,Jianping Zhang,Chuntai Liu
The epoxy nanocomposites with Fe 3 O 4 modified graphene oxide (Fe 3 O 4 /GO) were used to influence the micro-cracks resistance of carbon fiber reinforced epoxy (CF/EP) laminate at 77 K. Fe 3 O 4 /GO with good paramagnetic properties were prepared by co-precipitation method and used to modify epoxy for cryogenic applications. Fe 3 O 4 /GO modified CF/EP laminates were also prepared through vacuum-assisted resin transfer molding (VARTM). The results show that the Fe 3 O 4 /GO can effectively improve the mechanical properties of epoxy (EP) matrix at 77 K and reduce the coefficient of thermal expansion (CTE) of EP matrix. It also can obviously improve the micro-cracks resistance of CF/EP composites at 77 K. Compared to neat EP, the CTE of Fe 3 O 4 /GO modified EP composite is decreased 51.6%. Compared to CF/EP composite, the micro-cracks density of Fe 3 O 4 /GO modified CF/EP composite at 77 K is decreased 60.0%.
危险品化学品经营许可证（带存储）