Estudo do comportamento à tração direta e indireta de compósitos de fibras de juta

Abstract

The present study aims to evaluate the partial replacement of Portland cement by 50% of metakaolin and the use of different layers of fibrous reinforcement in screen format in cementitious composites. The reinforcement used was jute fiber fabric, 5x5cm mesh, arranged in 3 and 5 layers. For the mechanical evaluation, compression tests of the cementitious matrix, direct and indirect tension were carried out in three-point bending. The results show that testo f compression the modulus of elasticity was not changed and the maximum strength was reduced by 19.59% for the matrix with 50% replacement of cement by metakaolin. For the direct tension the results of the composites reinforced with 5 layers of jute fibers and with metakaolin substitution presented the best performances, reaching a "strain hardening" behavior but without multiple cracking. Regarding indirect tension, the results showed that the fiber contente influenced the load capacity of the composites. On the other hand, the higher fiber content obtained a better behavior regarding the capacity to absorvation deformations. For the composites without fibrous reinforcement, the cement-based matrix presented the best results, but when the composites contained some reinforcement layer the matrix with partial replacement of Portland cement proved to be more efficient, thus concluding that metakaolin was effective resulting in a free matrix of calcium hydroxide, allowing the fibers to perform better.However, the use of juta fibers reinforcement was not very effective due to factors that may be related to granular skeletal disorder and poor matrix fluidity for a good filling of the spaces between the cords of the mesh.