Study of the stability of zeolite suspensions for cement systems

Introduction. In Russia, the focus of scientific research in the construction industry is on the development of new materials with high functionality, durability, and strength. These materials also have various unique properties that make them suitable for a wide range of applications. Fine dispersed additives are used in the binder, for the construction of objects that require increased strength, or for repair work where early strength gain of the repair mixture is important. To improve the physical and mechanical properties of the hardened cement paste, which contains finely dispersed additives, it is necessary to consider the issue of uniform distribution of submicron particles in the volume of the cement composite. The study of this issue is one of the objectives of this study. Materials and methods. Fine dispersed zeolite, which has high ion-exchange, sorption, catalytic properties, was selected as the object of study, and the possibility of its introduction into the cement composition in the form of a stabilized suspension instead of mixing water was assessed/ Zeolite suspension with concentration of 10, 30, 50 g/l was prepared by mechanical stirring with a magnetic stirrer and ultrasonic dispersion under thermostatted conditions. The time of mechanical and ultrasonic treatment of suspensions was 20 min. Suspensions were prepared in two dispersion media – water and water-polymer (water + plasticizer). Physicomechanical tests of samples were carried out in accordance with current national and international standards and methods. Results. Studies of sedimentation stability of suspensions showed that the most stable suspension was stabilized by ultrasonic treatment and plasticizer. The sedimentation velocity of suspension particles in the first period was (3.43÷3.83)•10–6 m/s, in the second period – (0.98÷1.17)•10–6 m/s. The study of zeolite particle dispersion in suspensions showed that ultrasonic dispersion leads to a more significant shift in particle dispersion downwards from 25 μm to 3 μm, both in aqueous and aqueous-polymer suspensions with a concentration of 10–30 g/l. The conducted physical and mechanical tests of the samples showed that the introduction of an ultrasonic-stabilized aqueous-polymer zeolite suspension into the cement composition results in an increase in the initial and grade strength by 3.3 times and 51%, respectively. The analysis of the results for compressive strength showed the greatest efficiency when introducing a zeolite suspension into the cement composition instead of mixing water in an amount of 10–30 g/l. Conclusion. The studies conducted have shown the effectiveness of using ultrasonic treatment in combination with a plasticizer to stabilize the zeolite suspension. Stabilized zeolite particles, uniformly distributed in the volume of the cement matrix, act as a substrate for the nucleation and growth of crystal hydrate phases, thereby intensifying the process of hydration and formation of a crystal hydrate framework with a dense and strong structure of cement stone. Thus, the feasibility of considering zeolites as components of composite materials is a promising direction in solving multifaceted problems in the construction industry.