Fediuk R.S.

Candidate of Engineering Sciences (Ph.D.), Associate Professor, Far Eastern Federal University, Russia

STRUCTURE FORMATION OF C-S-H FROM THE POSITION OF MICROMECHANICS OF COMPOSITE MEDIA

https://doi.org/10.34031/2618-7183-2021-4-5-5-15
Аннотация
The creation of an environmentally friendly building material to protect the human environment can only be carried out from the position of a transdisciplinarity approach, taking into account modern achievements in geomimetics and micromechanics of composite media. A wide range of basalt-fiber-reinforced concrete based on composite binders has been developed, which have increased characteristics of impermeability and durability under extreme operating conditions. The nature of the influence of the composition and manufacturing technology of cement composites on the pore structure of the composite has been established, which has a positive effect on the characteristics of gas, water and vapor permeability. High early strength was obtained, which allows the use of materials for operational repair and construction in emergency situations. The positive influence of the composition of the developed composite on the performances has been proved. The water resistance of the modified composite provides a water pressure of 2 MPa for 148 hours, which corresponds to the W18 grade (for the control sample – W8), the frost resistance grade – F300. It was found that the water absorption of the modified concrete samples was lower than that of the control sample, which is explained by the decrease in the pore structure index λ by 28.4 times, and the average pore diameter by 3.05 times. The total pore volume of the modified concrete was lower and decreased with increasing dose of nanosilica.
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PERFORMANCES OF HIGH POROUS CELLULAR CONCRETE

https://doi.org/10.34031/2618-7183-2020-3-5-5-14
Аннотация
The widespread use of cellular concrete for enclosing structures forces researchers to develop ways to improve their performance and durability. Compositions of aerated and foam concrete with the use of waste heat power engineering have been developed. The optimal formulation ratios have been identified that contribute to the creation of a rigid interpore matrix and water-repellent pore protection. The regularities of the synthesis of aerated concrete and foam concrete were established, which consist in optimizing the processes of structure formation through the use of a polymineral cement-ash binder and a pore-forming agent. The mix composition intensifies the process of hydration of the system, which leads to the synthesis of a polymineral highly porous heterodispersed matrix. The increased activity and granulometry of aluminosilicates predetermine an increase in the number of contacts and mechanical adhesion between particles during compaction, strengthening the framework of the interpore partitions. The mechanism of the influence of the composition of the concrete mix on the microstructure of the composite is established. The calculated sound insulation of airborne noise shows sufficient characteristics for using aerated concrete blocks as enclosing structures. One of the main advantages of aerated concrete is its low thermal conductivity, which is especially important from the point of view of ensuring the energy efficiency of buildings and structures. Even in spite of the high values of open porosity of the developed aerated concrete, the rigid frame makes it possible to achieve almost 2 times higher frost resistance characteristics than that of the reference specimen.
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