Nanotechnological applied tasks of the increase in the efficiency of the hardening processes of cement concrete

Abstract

The scientific basis of the solution to the applied tasks of concrete technology through the use of «nano» tools, which provide the organization of the heterogeneous process of cement hydration and hardening, has been characterized. It is shown that the introduction of nanoadditives enables the direct regulation of the processes of structure formation in cement systems at the nanolevel. The effectiveness of the use of «nano» tools has been proposed to evaluate by means of complex criteria characterizing quantitatively the change in the activation energy, the rate of the process and time of its completion τ, the size and power consumption of the technology E while ensuring quality levels specified by R. According to the criteria, the monitoring of the results of the research has been made. Moreover, the most effective nanomodifying admixtures of two types have been identified. Type I is a compound nanoadditive based on nanoparticles SiO2 in combination with a superplasticizer, which mechanism of action is associated and also characterized by the increase in specific strength per unit measure the degree of cement hydration by 1.25–1.35 times. Engineering problems have been formulated. Moreover, the solutions are indicated for increasing the energy efficiency of the factory production of reinforced concrete products and structures. These solutions predetermine the reduction in the value of the maximum temperature for the curing of concrete, the reduction of the duration of the achievement of the required degree of cement hydration while concrete hardens, the reduction of time of cement concrete hardening to reach the regulated values of its strength, the increase in concrete strength per unit of cement consumption per m3 and energy efficiency of concrete hardening process in the preparation of reinforced concrete products. with the catalytic role in the processes of phase formation of nanoparticles of hydrated compounds. Type II is a nanoadditive based on chrysotile or carbon nanotubes providing the zoning of the structure of hardening and increase in the density of the system of dispersed particles addition. It is shown that the application of the given nanomodifiers in their optimal dosage makes the cement hydration process 10–30 times faster, which can be explained by the decrease in the activation energy of the process virtually 2–3 times. Furthermore, it also ensures the completion of the hardening process practically in the first twenty four hours. Besides, it is accompanied by the increase in the strength value by 45–65%.

Keywords

• cement hardening system
• concrete nanotechnology