Dynamic compressive behavior of high-strength engineered geopolymer composites

As a low-carbon geopolymer material, Engineered Geopolymer Composite (EGC) possesses high tensile ductility, holding tremendous potential for structural construction and reinforcement. However, the dynamic behavior of EGC has not been fully explored. In this study, the effect of various fiber lengths (6 mm, 12 mm, 18 mm) on the dynamic compressive response of EGC was investigated by Split Hopkinson Pressure Bar (SHPB) test. The findings indicated that as the fiber length increases, the workability and compressive strength of EGC decrease, while the tensile strength improves. In comparison to geopolymer matrix, EGC specimens exhibited a more significant strain rate sensitivity under impact loading, and fiber length had a notable effect on strain rate sensitivity. By adjusting the length of incorporated fibers, it was observed that EGC with 12 mm fibers demonstrated the highest dynamic compressive strength and dynamic increase factor (DIF), along with superior energy absorption capability. A modified CEB-FIP model was proposed to describe the dynamic behavior of high-strength EGC. The proposed model for DIF provides valuable guidance for optimizing EGC design and application.