Study of concrete properties with vegetal and polypropylene fibers for use in structural walls

摘要

The properties with addition of vegetal fibers (sisal and ramie) and of polypropylene for use in structural walls was studied in this research. An evaluation of the performance of the concrete with an addition of vegetable fibers and of polypropylene fiber was carried out, to verify the possible displacement. Were evaluated, the shrinkage under restrained conditions by ring test, as well the mechanical properties (compressive strength, splitting tension and static modulus of elasticity) and physical properties (specific mass, voids, immersion and capillary absorption). The contents used were 0.25 % and 0.5 % for the vegetable fibers and for the polypropylene fiber or 0.25 % content. In relation to the shrinkage under restrained conditions, it was observed that the addition of 0.25 % of fibers did not result in an increase in performance compared to concrete without fiber addition, but the addition of 0.5 % of vegetal fibers showed satisfactory results, being superior to the reference concrete. The mechanical properties of the concrete with fiber addition, generally lower than the reference concrete, did not undergo major changes, except for concrete with the highest ramie content, which did not present adequate fibers dispersion. The concrete with 0.25 % ramie presented the highest absorption and voids, among all the concretes studied. In relation to the absorption by capillarity, the concretes with addition of the vegetal fibers demonstrated better performance, that is, reduction of the absorption by capillarity. It was concluded that the substitution of polypropylene fiber by vegetal fibers, especially sisal, is plausible.