Influence of activation methods on the structural and technological characteristics of nanomodified cement compositions

Introduction. We studied the effect of nanosized silicon dioxide (SiO2) on the structural and technological characteristics of nanomodified cement compositions introduced together with activated mixing water. Materials and research methods. Activation of mixing water was carried out by means of magnetic field and ultrasonic action. For investigation the capability to maintain their properties for a long time, the stability of silica suspensions in activated water was studied. For finding out the effect of activated silica suspensions on the structure and properties of composite materials based on cement, the physical and mechanical properties of the studied compositions were explored. X-ray and differential thermal analysis of the hardened activated nanomodified cement paste were also carried out. Results and discussion. The positive role of the suspension of silicon dioxide in activated water was associated with a decrease in the microheterogeneity of the hardened cement paste, ensuring the stability of its physical and mechanical characteristics. Based on the above mentioned observations, a mechanism was proposed for more efficient incorporation of nanosized silicon dioxide into cement hydration processes both due to chemisorption with Ca(OH)2 in the hardening cement paste and due to the topological effect of nanoparticle localization in defects and ultramicrovoids of a crystallizing disperse system. Conclusion. The results show that suspensions of silica in activated water can maintain their properties for a long time. Graphical dependencies are shown, indicating the effectiveness of the use of activated silica suspensions in the production of cement composites. This quality makes it possible to obtain repair compounds with the required properties during construction work for various purposes.