Effects of Polyethylene Terephthalate Particle Size on the Performance of Engineered Cementitious Composites

This study utilizes polyethylene terephthalate (PET) aggregate of different particle sizes (21 μm, 107 μm, and 244 μm) to replace natural aggregate in the preparation of PET-modified engineered cementitious composite (P-ECC). The impact of PET aggregate particle size on the performance of P-ECC is examined herein from micro to macro levels. The focus is on the influence patterns and mechanisms of P-ECC's workability, its basic mechanical properties, and its microstructure. Crack parameters are processed to quantitatively analyze crack development patterns. Using microscopic techniques, the interfacial transition zone (ITZ) between different aggregates and the cement matrix is compared, and the failure mechanism of P-ECC is analyzed. The results show that the incorporation of PET aggregate can improve P-ECC's workability and reduce its self-weight, but incorporation has a negative effect on compressive strength. Additionally, the particle size of PET aggregate significantly affects the uniaxial tensile performance of P-ECC. Compared to conventional ECC, the tensile strength of P-S (21 μm PET) increased the most markedly (18.1%), and the ultimate tensile strain of P-M (107 μm PET) increased the most markedly (66.0%), with both demonstrating good crack control and deformation energy dissipation capabilities. The uniaxial tensile performance of P-L (244 μm PET) was lower than that of the conventional ECC. Microscopic tests revealed that the increase in PET aggregate particle size enlarges the ITZ width and its surrounding pores. Appropriate pore enlargement is beneficial for enhancing tensile ductility, while excessive pores have a negative effect. The study results reveal the impact of PET aggregate particle size on the performance of P-ECC, providing new insights for the performance optimization of ECC.