Estudo das características física, mecânica e química de compósitos cimentícios reforçados com tecido de juta e malva tratado e adição de materiais pozolânicos

Abstract

The present research presents the development and characterization of cementitious composites reinforced with jute and malva fibers textile. In order to increase the durability of these materials, a free matrix of calcium hydroxide was used, a degrading agent of natural fibers in a cementitious environment. The treatment of the textile was performed by the hornification process, aiming to reduce the fiber volume variation and consequently to improve fiber-matrix adhesion and durability. Reinforced cementitious plates with two layers of jute and malva textile were produced by a pneumatic system and exhibited double-cracked flexural tensile behavior for most experimental conditions (plates reinforced with treated and untreated textile and matrix of reference and modified by 40% metakaolin) at twenty and eight days. The composites reinforced with textile treated for 10 cycles of hornification, presented multiple cracking only in the middle third of the specimens. The durability of the composites was investigated by means of the accelerated aging process (50 wetting and drying cycles) and they were evaluated by tensile strength tests, microstructural analysis and physical characterization. In the composites with metakaolin, the hornified and untreated textile did not result a significant increase in flexural tensile strength (MOR) in relation to the reinforced reference matrix (about 6.5 MPa for all composites), however, those presented high specific energy (more than 100% increase). After aging, the matrix modified and reinforced with textile in both conditions (untreated and hornified) were efficient, since they preserved the mechanical characteristics, mainly MOR (6.5 MPa). This was not observed for the reinforced reference matrix, in this case, there was a 25% loss in resistance (MOR = 5.15 MPa).