Mechanism of PVA Fiber Influence in Foam Concrete: From Macroscopic to Microscopic View

Abstract

Fibers are added to foam concrete to improve its mechanical properties. Despite several studies about the performance of fiber-reinforced foam concretes, the mechanism of fiber reinforcement in foam concretes is not understood. In this research, the microstructural properties of Polyvinyl alcohol (PVA) fiber-reinforced foam concretes were quantitatively analyzed with different fiber sizes and fiber contents. The relationship between different parameters was investigated to understand how and why fibers influence the microstructural properties of foam concrete. In addition, a regression model was developed to analyze how fibers influence the compressive strength and which parameters have the highest impact on the compressive strength. The results show that the mechanism of reinforcement is different in high-density and low-density foam concretes. In high-density foam concrete, fiber distribution had a dominant impact on the compressive strength, but the pore structure did not show much influence on the strength. However, in low-density foam concrete, fiber distribution significantly influenced pore structure, and an improved pore structure provided higher compressive strength. The size of fibers significantly affects fiber reinforcement efficiency. The large-diameter fibers outperformed small-diameter fibers in improving the compressive strength of high-density foam concrete. In contrast, the small-diameter fibers showed better reinforcement efficiency in low-density foam concrete. By optimizing the PVA fiber size and content, the compressive strength of low-density and high-density foam concretes can be improved by 45.3% and 15.5%, respectively.