Enhancement Mechanism of Strength, Toughness, and Crack Resistance of Cementitious Mortars by Glass Fiber and Epoxy Resin Adhesive

Cement-based materials possess good compressive properties but are brittle and have low tensile strength. Hence, this study uses glass fiber (GF) and epoxy resin adhesive as reinforcing materials to configure glass fiber–reinforced mortar (GFRM). Additionally, it investigates the effect of GF volume substitution rate (0%, 5%, 10%, 15%, 20%) and epoxy resin adhesive mass fraction (0%, 3%, 5%, 7%, 9%) on the density, water absorption, porosity, flexural strength, compressive strength, split tensile strength, and material brittleness. The study’s results show that the density of GFRM gradually decreases while the water absorption and porosity increase with the rise in GF volume substitution rate. Similarly, the density, water absorption, and porosity of GFRM gradually reduce as the epoxy resin adhesive mass fraction improves. In addition, as the GF volume substitution rate rises, the flexural strength, compressive strength, and split tensile strength of GFRM initially increase and then decrease. The higher the mass fraction of epoxy resin adhesive, the greater the flexural strength, compressive strength, and split tensile strength of GFRM. Notably, the flexural strength reached a maximum of 18.4 MPa at a 10% GF volume substitution rate, while the compressive strength and split tensile strength reached their maximum values of 54.6 and 6.95 MPa, respectively, at a 15% GF volume substitution rate. Adding GF and epoxy resin adhesive reduces the brittleness of the mortar. Microanalysis of the internal structure of GFRM using scanning electron microscopy (SEM) revealed the strengthening mechanism of GF and epoxy resin adhesive on GFRM. Based on the existing model, a prediction model for the strength relationship of GFRM is established through the fitting analysis of the test data, and the predicted values of the model are found to be in good agreement with the test values.