Discarded polyethylene terephthalate (PET) bottles have damaged our ecosystem. Problems of marine fauna conservation and land fertility have been related to the disposal of these materials. Recycled fibre is an opportunity to reduce the levels of waste in the world and increase the mechanical performance of the concrete. PET as concrete reinforcement has demonstrated ductility and post-cracking strength. However, its performance could be optimized. This study considers a statistical-experimental analysis to evaluate recycled PET fibre reinforced concrete with various fibre dose and aspect ratio. 120 samples were experimented under workability, compressive, flexural, and splitting tensile tests. The results pointed out that the fibre dose has more influence on the responses than its fibre aspect ratio, with statistical relation on the tensional toughness, equivalent flexural strength ratio, volumetric weight, and the number of fibres. Moreover, the fibre aspect ratio has a statistical impact on the tensional toughness. In general, the data indicates that the optimal recycled PET fibre reinforced concrete generates a superior performance than control samples, with an improvement similar to those reinforced with virgin fibres.
The inductive method proposed by Torrents et al. [1] and improved by Cavalaro et al. [2] is used to assess the fibre content and distribution in steel fibre reinforced concrete, providing valuable information for the design and the quality control. Despite several advantages, the method presents limitations. On one hand, it was conceived for the test of cubic specimens, which complicates its application in existing structures due to the difficulty to extract cubic cores. On the other hand, only a partial characterization of the fibre orientation is obtained given that the determination is restricted to the three axes of the specimen. With these measurements, it is not possible to derive the fibre orientation in other directions different from the ones used to test the sample. The objective of this paper is to propose an assessment of the fibre content and distribution in any direction using the inductive method and cylindrical specimens. For that, first a modification of the method is proposed. Then, new equations are deducted to generalize the test to samples with different shapes and to assess the anisotropy level as well as the directions with the maximum and the minimum fibre contribution. Next, an extensive experimental program and FEM numerical simulations are performed to validate and to determine the accuracy of the formulation developed. The results show that the application of these equations and the execution of only one additional measurement per specimen are enough to determine the fibre profile in all in-plane directions with a high accuracy.
A bonded concrete overlay consists of a concrete layer poured over a deteriorated pavement. Its mechanical performance depends on the quality of the bond between the lower and the uppermost layers. This paper reports an extensive experimental program to evaluate bond strength between Conventional Concrete (CC) and Asphalt Concrete (AC) substrates and Self-Compacting High-Performance Concrete (SCHPC) overlays. In all, 8 interface treatments are tested under Direct Tension, pure shear “LCB”, and compressive Slant Shear tests. The results show that direct pouring of the SCHPC overlay over CC and AC substrates produces similar or higher strengths than the other treatments analyzed.Peer ReviewedPostprint (author's final draft
Abstract-The inductive method has shown to be a good method for the estimation of fiber dosage in Steel Fiber Reinforced Concrete. The current formulations reported a strong correlation between inductance and fiber content, as well as orientation. The objective of this article is to study how the inductive measurements are affected by fiber properties, such as its dimensions, magnetic characteristics and the samples temperature. The results, obtained from numerical, simulated and experimental data, propose a shape factor to be applied in the measurements to take into account the aspect ratio of the fibers. As for the temperature, the error introduced is less than a 1 %, so a corrective factor is not essential.. Index Terms-fiber content, fiber orientation, inductive method, magnetic sensors, nondestructive testing, steel fiber reinforced concrete
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