PROPERTIES OF SELF-COMPACTING CONCRETES WITH A COMPLEX ADDITIVE-MODIFIER

Abstract

The study investigates the influence of a complex modifying admixture (CMA) containing the superplasticizer Melflux and polyvinyl acetate dispersion on the properties of self-compacting fine-grained concretes based on fly ash and cement. The aim was to determine the optimal CMA composition for achieving balanced compressive strength, flexural strength, water absorption, and abrasion resistance. Experiments were carried out using a three-level, three-factor B3 design with variation of the water-to-binder ratio and CMA component contents. The results show that the water-to-binder ratio is the dominant factor affecting strength: increasing W/B significantly reduces compressive strength, while the effect on flexural strength is less pronounced. Increasing the Melflux content at constant W/B enhances strength, whereas excess polyvinyl acetate reduces it. With higher polymer content, the f_cm/f_ct,f ratio decreases due to adsorption-based modification of the cement matrix structure. Water absorption correlates well with compressive strength and decreases as the Melflux content increases, reaching minimum values when only the superplasticizer is used. A significant reduction in abrasion was also observed in concretes containing PVAD, even at low polymer-cement ratios. The results confirm the effectiveness of complex polymer–mineral admixtures in improving the durability and crack resistance of self-compacting concretes.