Complex additives based on carbon nanotubes for rapid hardening high strength concrete
Mail purpose of the research was to develop cost-optimal compositions of concrete class B45 in cement consumption up to 360-380 kg/m <sup>3</sup>, and to develop strength of concrete products (more than 15 MPa) for no more than 8 hours of curing. Developed area of the concrete composition are concrete blocks lining tunnels Kazan metro derived from high (B45) and waterproof (W> 10) concrete. Analysis of the results shows that with consumption of cement 490 kg/m <sup>3</sup> the best results were recorded in the composition with developed additive. The strength of the concrete in the early stages of hardening by 36 % more than in the control composition. By reducing the flow of cement to 350 kg/m <sup>3</sup> at 8 o'clock stripping strength gaining only 2 of concrete mix and both are modified by the KDU-1 with carbon nanotubes. Durability in a 28 day curing reach values 72,3 MPa, which is higher than the strength of the control by 43 %.