Mixer influence on pore characteristics and fiber dispersion in Engineered Cementitious Composites across various strength grades

Abstract

Variability in pore characteristics and fiber dispersion among Engineered Cementitious Composites (ECC) prepared with different mixers crucially determines their mechanical behavior, highlighting the importance of mixer selection in ECC processing. However, the research on the mesoscopic performance of mixer types is currently inadequate. To address this deficiency, this paper employed three prevalent ECC mixers—pan, handheld, and planetary—to analyze the macroscopic performance and microscopic features of ECC across all strength grades. Utilizing CT-scan-based 3D reconstruction technology, it investigated the interplay between porosity traits, fiber dispersion, and the mechanical properties of ECCs fabricated with these mixers at various strength levels. Findings demonstrate the planetary mixer's dominance in producing ECC with superior compressive, tensile, and flexural strengths due to its ability to ensure even fiber distribution and form a more spherical pore structure. The advantage of planetary mixers becomes more evident with increasing compressive strength grades, consistently maintaining a fiber volume fraction of 1.5–2.5 % at higher strengths. In comparison, while handheld mixers achieve moderate performance, they fall short of planetary mixers' efficiency in attaining homogenous pore structures and fiber distribution. Pan mixers exhibit declining fiber distribution and increased pore irregularity as strength enhances, resulting in the poorest mechanical performance. This study delineates the impact of mixers on ECC's properties and reinforces the critical role of mixer choice in achieving desired mechanical characteristics in advanced engineering applications.