Evaluation of the feasibility application of Malva fibers in cement-based composites

Abstract

The use of natural fibers as reinforcement in cementitious composites has been explored as an alternative to the development of new materials for civil construction. Research that explores macro and microstructural parameters in a combined way in composites reinforced with natural fibers are still poorly explored. In this work, the compatibility effect of Malva (Urena lobata L.) on fiber-reinforced cement composites was evaluated dosages (0, 2 and 5%) with untreated and treated fibers (30 min in 5% of NaOH solution) were mixture with Portland cement and lime to application as coating mortars. Reaction rate by isothermal conduction calorimetry and 28 days reaction products of pastes were characterized with XRD, SEM, and MIP, as well as technological properties of mortars, such as mechanical strength, water absorption, and consistency were investigated in all dosages. The findings showed an increase in the cross-compatibility index of treated fibers (around 5%), resulting in a denser microstructure with reduced portlandite and calcite formation when compared with untreated Malva, due to the removal of sugar and impurities obtained with the NaOH treatment. MIP results exhibited a reduction on total porosity from ∼12% to ∼6%. Mechanical strength was lower in the untreated fibers (∼35% less than reference) with no significant difference with higher content, nonetheless, fiber treatment presented similar results to the reference. Water absorption were 8% lower to treated fibers. The incorporation of 2% by weight of treated Malva fibers in cement-based mortars presented better efficiency, offering a promising new material for cladding walls in building materials.