Experimental study and evaluation of bonding properties between fiber and cement matrix under sulfate attack

The toughening effect of fibers on cementitious composites mainly comes from the bridging effect of fibers, and the core of the bridging effect depends on the bonding performance of fibers to the cement matrix. To study the fiber-cement matrix bonding performance under the action of sulfate-dry and wet cycles of erosion, fiber pull-out tests with different Na2SO4 solution con-centrations (0-15%) and fly ash admixtures (0-30%) were carried out in this paper. Based on the principle of energy dissipation, the mathematical relationship between the toughness index and energy absorption index of fiber-cement-based mortar was established, and a comprehensive evaluation method of fiber-cement matrix bonding performance based on the weight determined by the CRITIC method is proposed. The results show that 15% Na2SO4 solution has a great in-fluence on the erosion rate and erosion degree of interface bonding performance, and the peak load corrosion resistance coefficient is reduced by 43.7%. When the content of fly ash is 20%, the interface transition zone has the best resistance to sulfate attack, and the maximum value of bonding performance index B is 0.59 when the dry-wet cycle is 60 times. The findings can provide a theoretical basis for the interfacial adhesion resistance to sulfate attack and its degradation law under sulfate attack.