Desenvolvimento de fibras metálicas espaciais e avaliação experimental do comportamento de compósitos de concretos com adições híbridas de fibras

Abstract

The addition of fibers to a cementitious matrix provides several benefits to the performance of the composite, including the control of cracking, tenacity gain, increased tensile strength, among others. In view of this, a random and more homogeneous distribution of the fibers along the matrix is sought. It's expected that the proposition of a reinforcement element defined from the orthogonal union of filaments - spatial fiber - will contribute to a more uniform and homogeneous distribution of the matrix reinforcement, avoiding imperfections in the composite and maximizing the reinforcement efficiency. This dissertation aims to create a spatial fiber model and add it in a conventional concrete matrix, either alone or in combination with steel macro fibers monofilaments and polypropylene microfibers, evaluating the performance of the resulting composites in terms of workability, compressive strength, indirect tensile strength and tenacity. In addition, the distribution of the fibers inside the concrete matrix and their influence in the final performance of the composite were evaluated. For this, an experimental program was carried out with 18 composites, each with a different combination of spatial fibers, steel macro fibers monofilaments and polypropylene microfibers. It was performed the axial compression tests according to ABNT NBR 5739: 2007, the flexural tensile strength tests according JSCE-SF4 (1984) and ABNT NBR 12142:2010, and the tenacity tests according to JSCE-SF4 (1984). Based on the results obtained, it was concluded that the spatial fibers presented satisfactory performance, both alone and hybridization, because they didn't affect the compressive strength, improved the tensile behavior in 37,6% and reached a tenacity factor of 3,4 MPa. Also, it was observed that the workability decreased in relation to the concrete without fibers, but the capacity of compaction was not impaired.