The effectiveness of cement mortarsfor the rapid repair and rehabilitation of engineering structures can be improved by nanomodification. The article presents the results of studies of the properties of rapidly hardening cement mortars containing fly ash and polycarboxylate ether. A nanotechnological approach using sol-gel technology was implemented to produce rapid hardening cement mortars for rapid repair. The results demonstrated that cement mixtures with the addition of a nanomodifier are characterised by increased early compressive strength and adhesive strength. It has been confirmed that the introduction of C-A-N-H-PCE nanocomposite as an effective nanoadditive, which was synthesised by the sol-gel technology, allows obtaining rapid-hardening non-shrink cement mixtures. The research demonstrates the potential benefits of using nanomodified cement mixtures over conventional ones for the rapid repair of damaged concrete, offering improved performance. The high construction and technical properties are improved by increasing the transitional contact zone and improving the macroscopic properties of the bonding surface. This solves the problems associated with the need to increase the early strength and adhesive strength of cement mixtures while ensuring reduced shrinkage deformations. As a result, it is possible to rapidly repair and rehabilitate damaged fortifications in combat zones and difficult construction conditions.