Fibre reinforcement of cement mortars for reinforcement of masonry buildings: an experimental investigation

Existing masonry buildings are often structurally vulnerable and subject to deterioration, as well as increased risks from the more frequent hazards caused by climate change. This study presents an experimental analysis of fiber-reinforced mortars, emphasizing their applications in conservation engineering. The primary goal is to enhance the mechanical properties of mortar renders by incorporating various synthetic and natural fibers, including polypropylene (PP), hemp (HF), coconut (CF), sheep wool (SW), steel (SF), glass (GF), and fishing net fibers (FN). The experimental campaign involved evaluating the flexural and compressive strengths of mortar specimens reinforced with different fiber types and volume contents, comparing them to control (unreinforced) specimens. The results demonstrated significant variations in mechanical performance depending on the fiber type and content, and the failure mode analysis indicated that fiber reinforcement generally resulted in more ductile behavior compared to the control specimens, with fibers bridging cracks and distributing stress more evenly across the cement matrix. The CF and PP fibers significantly enhanced the mechanical properties of the mortars. Specifically, CF at 1.5% volume content showed the highest improvement in flexural strength, achieving 10.21 MPa, while PP at 2% content provided the most significant increase in compressive strength, reaching 26.82 MPa. These findings highlight the superior performance of CF and PP fibers in reinforcing cement mortars. It is concluded that optimal fiber content is crucial, as exceeding this threshold may lead to reduced performance due to improper bond formation within the mortar matrix. Test results offer new data and information for creating more resilient and durable fiber-reinforced cement renders to protect and strengthen old masonry structures.