Characterisation of natural fibres for enhancement of concrete properties.

Abstract

The use of fibres as reinforcement of composites is widely applicable for mechanical, materials and construction sectors. For instance, most of those fibres are not produced from renewable sources or by ecological procedures and researchers have been trying to develop smart solutions to replace them efficiently keeping a competitive price. Natural fibres are commonly considered as an ecologic alternative. They can be extracted from abundant vegetable, mineral or animal sources and if submitted to adequate treatment, they are able of providing important materials for the industry. Despite the aim of this paper is focused on concrete, results obtained experimentally for this study are still applicable for other purposes of application. Considering natural fibres as light and low-cost materials, when added to a composite mixture, they can become a sustainable alternative for other fibres to produce materials with better thermo-acoustic properties and reducing weight and density of the final composite. One of the current issues related to natural fibres is that while the currently used fibres are produced under controlled methodology and their properties can be easily characterized, natural fibres are still no standardized and even under the same process of extraction, singular fibres, when compared among themselves can present distinct characteristics. This study examines results obtained for mechanical properties of flax, jute, hemp and basalt fibres found experimentally, compares and analyses the compression strength of concrete with the addition of hemp, basalt, steel and polymer fibres into concrete mixture designed under the same parameters. As result for singular fibres, flax and basalt presented the highest tensile strength and Young`s modulus when compared to jute and hemp. On the other hand, when added to concrete, hemp fibres in a proportion of 0.5% achieved results comparable with the mixtures containing polypropylene in 1.0% and Steel in 0.15%.