Muminov Ikhtiyor Subkhonkulovich, Akramov Avazjon Abdulloevich, Abdurakhmanova Gulzora Alimjаnovna

Annotation:

An effective clinker-free hydraulic binder system is achieved through the sodium carbonate activation of high- and lowcalcium fly ash blends. Upon hydration, an alkaline environment is established, triggering the pozzolanic and hydraulic reactivity of the ash constituents. This process results in a stable, water-resistant matrix exhibiting compressive strengths typically ranging from 10-20 MPa or higher. While hydrothermal treatment significantly accelerates strength development, managing volumetric deformations-driven by the hydration of free CaO – remains a critical challenge. The magnitude of such expansion is governed by a synergy of factors, including the chemical profile of the ash, its specific surface area, and the applied curing temperature profile. Precise calibration of these variables ensures that expansion remains within regulatory limits. Furthermore, the incorporation of ultra-fine silica serves as a stabilizing agent, effectively mitigating destructive effects even when utilizing coarse ash fractions with high free lime content.

Keywords: fly ash, composite binders, silica fume, waste recycling, calcium oxide, low-calcium fly ash, high-calcium fly ash, geopolymer concrete.