Investigation of the Multiparameter Mix Proportion Design and Mechanical Properties of Polyvinyl Alcohol-Engineered Cementitious Composites

In contrast with its strong compressive performance and durability, the low tensile strength of concrete often leads to a range of issues during long-term application, including deformation, cracking, and even fracturing of the structure. The addition of polyvinyl alcohol (PVA) fibers to concrete can effectively improve the toughness of materials. However, currently, the majority of studies on polyvinyl alcohol-engineered cementitious composites (PVA-ECC) have focused primarily on the influence of a single factor, such as the PVA fiber content, on the properties of materials, while research that elucidates the interplay between the mechanical properties of PVA-ECC and various mix parameters, to our best knowledge, is lacking. In this study, based on the principle of orthogonal testing, 25 groups of specimens with different mix ratios were designed for experiments, and the effects of the water-binder ratio, sand-binder ratio, fly ash content, and PVA fiber content on the properties of the materials were investigated. On the premise that the fluidity of the material can meet the basic working performance requirements, it was suggested that the content of fly ash should be 35%-52.5%, the water-binder ratio should be 0.375, the sand-binder ratio should be 0.375, and the PVA fiber content should be 1.5%. Under this mix ratio, the strength of the material could reach that of C40 concrete, the compressive toughness could reach more than 10 times that of ordinary concrete, and the ultimate tensile strain under uniaxial tension was close to 3%. These research results can provide a systematic and comprehensive reference for the mix design of PVA-ECC in engineering practice.