Analysis of the combination of glass and polypropylene fibers on the mechanical properties of mortar

This article investigates the impact of incorporating glass fibers (GF) and polypropylene fibers (PPF) on the mechanical properties of two types of load-bearing mortars, P1 and P2. Glass fibers at 1%, 3%, and 5% were combined with polypropylene fibers at 0.1%, 0.3%, and 0.5% by weight of cement. The GF and PPF had lengths of 51 mm and 50 mm, respectively. Mortar mixes were prepared with proportions (1:3) and (1:4) of cement and sand, corresponding for bearing walls of type P1 and P2, for when high strength is required and when they have moderate structural requirements. No superplasticizer was added to the mixes. Mortar was tested for flowability, compressive strength, flexural strength, adherence, tensile strength, masonry prisms and diagonal compression in masonry walls for different curing periods at 7, 14 and 28 days. A cost-benefit analysis per m² was also performed for the fiber-reinforced mortar. Results show that fiber hybridization improved compressive, flexural, tensile, and shear strength in walls, as well as adhesion, by up to 60% compared to the control mortar. Increasing fiber content reduced flowability but promoted hydration products and contributed to a denser matrix, enhancing strength and the interface area between fibers and the cement matrix. For small fiber proportions (1% GF and 0.1% PPF), a direct correlation was observed between fiber content and improved mechanical properties. The cost analysis indicated an increase of 25.46% and 24.06% per m² for P1 and P2 mortars, respectively, compared to conventional mortar, offset by the substantial improvement in strength.