Research on the Mechanical Properties of Strain-Hardening Geopolymer Composites Reinforced with PE Fibers

Through fiber toughening composite technology， a fiber-reinforced geopolymer composite with quasi-strain-hardening characteristics was designed and prepared， effectively addressing the shortcomings of traditional geopolymers such as poor toughness and crack sensitivity. First， the initial mix proportion design of the composite was proposed through orthogonal experiments， followed by single-factor experimental studies. The optimal mix ratio was determined based on test results including rheological properties， compressive strength， flexural strength， X-ray diffraction （XRD）， and scanning electron microscopy （SEM）. Finally， direct tensile tests and four-point bending tests were conducted to investigate its tensile behavior. The results demonstrated that under alkali activation， silicon-aluminum substances in the matrix gradually dissolved and condensed into a —Si—O—Al— network structure. The formation of C-S-H and N-A-S-H gels within the material contributed to its strength. When the water-to-binder ratio was 0.5， fiber dosage was 2%， sodium silicate modulus was 1.2， and alkali activator content was 20%， the composite exhibited excellent mechanical properties （28-day compressive strength： 46.25 MPa， flexural strength： 7.70 MPa， tensile strain： 3%， and bending strength： 13.3 MPa）. During tensile testing， multiple fine cracks appeared on the specimen surface， and the stress-strain curve displayed distinct quasi-strain-hardening characteristics.