THE INFLUENCE OF QUARTZ PARTICLE SIZE ON THE DEGRADATION OF CEMENT STONE UNDER HIGH TEMPERATURE AND HUMIDITY

This article explores the effect of quartz aggregates and fillers on the thermal resistance of concrete. Experimental data indicate that the hardening kinetics of concrete samples with varying quartz particle sizes in water at 80 °C differ significantly from those in normal conditions (20 °C). The thermal resistance coefficient of samples increased with the particle size of quartz, from 0–0.16 mm to 0.16–0.63 mm to 0.63–2.5 mm, showing values of 1.15, 1.40, and 0.84, respectively, after 12 months of testing. Ultrasonic testing revealed that fine quartz sand forms a structure highly resistant to elevated thermal and moisture stress, which significantly reduces the rate of thermal corrosion. Concrete samples with coarse quartz exhibited gradual degradation, while those with fine quartz particles tended to degrade more quickly. The cause of destruction in conditions of thermal corrosion is attributed to recrystallization processes of hydrated phases, accompanied by the dissolution of small hydrate particles and the formation of larger particles, resulting in the formation of α-dicalcium silicate hydrate, which possesses poor binding properties.