Performance optimization of concrete modified with composite adhesive incorporating finely dispersed volcanic Ash

This study investigates the mechanical performance, durability, and bond behavior of concrete modified with a composite adhesive incorporating finely dispersed volcanic ash. The objective is to determine optimal mixture parameters for B30 class concrete using a three-factor Box-Behnken experimental design, considering filler content (20-60 %), water-to-binder ratio (0.25-0.45), and adhesive consumption (200-450 kg/m 3 ). Concrete specimens were evaluated in terms of compressive and flexural strength, elastic properties, frost resistance, and bond strength to reinforcement under both natural curing and heat-moisture treatment (80 °C). The results show that adhesive consumption is the dominant factor influencing compressive strength. Optimal parameters (20-25 % filler, water-binder ratio of 0.25-0.28, and adhesive consumption of 440-450 kg/m 3 ) ensure a compressive strength of 48-49 MPa, exceeding the requirements of class B30. Frost resistance increased up to F300, while bond strength reached 6.2 MPa, approximately three times higher than that of conventional concrete. Heat-moisture treatment further improved strength by 10-15 %. The observed improvements are attributed to the synergistic interaction between the composite adhesive and volcanic ash, leading to pore refinement and the formation of additional secondary C-S-H phases. The proposed approach enables a reduction in cement consumption by 130-150 kg/m 3 , contributing to improved economic efficiency and reduced environmental impact.