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[Display omitted] • The affinity of cement impregnation with the matrix leads to a higher bond strength. • A denser interphase zone is seen for cement-impregnated yarns in a cement-based matrix. • Hybrid composites exhibit distinctive bilinear σ-ε response due to SHCC ductility. • Mineral impregnations clearly outperform epoxy one in reducing crack width. Hybrid externally-bonded reinforcements are considered a viable technique for strengthening existing concrete structures. They combine high-performance impregnated textiles with matrices containing dispersed microfibres to foster the ductility and toughness of the composite system. In this paper, the mechanical performance of textile-reinforced strain-hardening cement-based composites (TR-SHCC) is investigated in detail. A novel high-performance inorganic binder based on limestone calcined clay cement (LC3) is reinforced with both polyethylene (PE) dispersed microfibres and carbon fibre (CF) textiles as continuous biaxial reinforcement. The CF yarns are impregnated by an automated process to improve the monolithic response under uniaxial tensile loading and to ensure high production consistency. Fully inorganic suspensions, i.e., geopolymer and cement-based, are being investigated, as they can provide superior thermal stability compared to traditional polymeric impregnating agents. Interphase adhesion is investigated by single-yarn pull-out tests, microscopy and µCT at various micro scales. On the one hand, the improved adhesion promoted by cement impregnation resulted in the finest and most diffuse crack pattern. Conversely, the strength of the overall composite is mainly governed by the tensile failure of the yarns, irrespective of the bond, and dispersed fibres consistently improve the post-cracking stage and the strength of the hybrid composites. [ABSTRACT FROM AUTHOR]

Existing concrete or reinforced concrete structures feature, as a rule, a relatively low resistance to various types of dynamic loading, such as earthquake, impact or blast. This makes it extremely important to develop and propose effective and feasible solutions for strengthening the structures prone to such loading. The contribution will provide an overview of the Research Training Group GRK 2250 “Mineral-bonded composites for enhanced structural impact safety” established in 2017 by the German Research Society (DFG) at the TU Dresden. The goal of GRK 2250 is to bring substantial improvements in the impact resistance of existing buildings by applying thin layers of strengthening material. By using innovative, mineral-bonded composites, public safety and the reliability of vitally important infrastructure should be significantly enhanced. The scientific basis to be developed will additionally enable to build new, impact resistant structures economically and ecologically. [ABSTRACT FROM AUTHOR]