Efecto de las fibras de coco sobre la resistencia a la flexión de mezclas de hormigón

Abstract

Concrete is a brittle material and low resistance to flexo traction, due to their lack of ability to withstand deformation. These limitations could be overcome by incorporating a reinforcement, as natural fibers. The objective of this study was to analyze the effect of the coconut fibers treated and untreated PMMA on the flexural strength of concrete mixtures, as a substitute of part of a fine aggregate proportion of 2.5, 5 and 10% in volume. For this, we determined optimum design of concrete mixture to a water / cement ratio of 0.48, then the mixtures were prepared with untreated coconut fibers averages two lengths (3-4 cm; 5-6cm) and treated with PMMA (≤ 4cm). The concrete reinforced with chemically treated fibers with the PMMA, gave better results in the modulus of rupture at high temperatures, in the modulus of rupture to cycles of heat and moisture and presents a decrease in the loss of the water with the fibers without treatment; this was due to the fact that the fibers do not demeaned by the protection offered by the PMMA of chemical attack that with the time he produces the alkalized water by the alkali elements present in the cement. The highest values in the modulus of rupture were obtained for mixtures with 2.5 % and 5% of fibers treated short size. The tensile strength in bending of the mixtures at different temperatures exhibited markedly decreases when the temperature is above 200 ° C.