Papers by Keyword: Fibre Reinforcement

Abstract: This study investigates the enhanced mechanical properties of pineapple leaf fibre-reinforced polymer composites and their potential applications in sustainable industries. The objectives were to assess the impact of varying fibre compositions on the microstructural and mechanical properties of the composites. Extracted fibres from pineapple leaves were used as reinforcing materials in a low-density polyethylene matrix with varying mass fraction from 0 wt.% to 12 wt.%. Scanning Electron Microscopy were used to analyse the microstructure, and results reveal a dynamic relationship between fibre content and the composite's mechanical behaviours. Mechanical properties measured all exhibited significant improvements with increasing fibre content, reaching their peaks at 9 wt.% fibre content. These enhancements are attributed to the effective load-bearing capability of the fibres. Beyond this optimal point, a drastic reduction in mechanical properties was observed which might be due to fibre agglomeration and other challenges. Ductility, on the other hand, showed a decreasing trend with increasing fibre content, indicating a trade-off between fibre reinforcement and ductile behaviour. These results offer insightful information for modifying the mechanical characteristics of polymeric composites reinforced with pineapple leaf fibres for potential eco-friendly applications.

Abstract: Throughout time, the use of lignocellulosic resources has been implemented in the development of building materials. Among these resources, natural fibers are used as mineral binders reinforcement due to their specific mechanical properties. This experimental investigation focused on effect of flax and hemp fiber reinforcement on the resistance of pozzolanic-based mortars to cracking due to restrained plastic shrinkage. Results were compared with polypropylene fiber reinforcement and with control mortar without fibers. The quantity of fibers added to the mortar mix were respectively 0.25% - 0.5% by mass of binder for polypropylene fibers and 0.5% - 1% by mass of binder for flax and hemp fibers. All fibers have a similar length of 12 mm. The cracking sensitivity was evaluated based on two different methods: the first consists in casting the mortar in a metal mold with stress risers whose criteria are inspired by the ASTM standards. The second consists in pouring the mortar on a brick support. In order to assess the effect of fibers on cracking due to restrained plastic shrinkage, the number of cracks, total crack area and maximum crack width within the first 6 hours after casting were determined using digital image correlation (DIC). Results showed that the flax and hemp fibers were more effective in controlling restrained plastic shrinkage cracking compared to polypropylene fibers. With a natural fiber of 1% by mass of binder, maximum crack width was reduced by at least 70% relative to control mortar based specimens. Natural fibers show great ability to propensity for cracking due to restrained plastic shrinkage; so that, they could be an alternative and ecological solution for polypropylene fibers.

Abstract: In the paper, the resistance of concrete to the erosive effect of water from a water jet was monitored. The tests were performed on concrete without the addition of fibres and on concrete with the addition of polypropylene fibres and steel fibres. The water flow hit the concrete surface at an angle of 90°. The water flow rate was 1.1 l/min and the water pressure was 80 MPa. After blasting the concrete with water jet, no cracks in the concrete were observed and the intended rugged surface relief was created. Steel fibres remained firmly anchored into the cement matrix.

Abstract: Veneer plywood is established in building construction, interior finishing and vehicle construction. Particularly in automotive or ship interior applications, the requirements with regard to strength and stiffness properties are increasing. At the same time, the weight of the panel materials used is to be reduced. The development presented here is a new type of lightweight basalt fibre-reinforced poplar veneer plywood and at the same time rigid alternative to the established birch veneer plywood. By adapting the adhesive and the reinforcing semi-finished products, the material and manufacturing costs are comparatively low. The bonding of the fibre reinforcement to the carrier material is achieved by means of adapted wood adhesives (e.g. polyvinyl acetates), which are also used as matrix material for the fibre reinforcement. An application of the reinforcement layer is integrated into the coating process (e.g. with High Pressure Laminate HPL decorative fabrics) of the carrier material. Essential advantages compared to conventional board materials are shown in this paper. The research results were achieved at the Institute for Structural Lightweight Construction of the TU Chemnitz in cooperation with the company Toms Gerber GmbH within the ZiM cooperation project FuBa.

Abstract: Gas permeability of concrete is a property, which is recognized as one of the basic indicators of its durability. Measuring of the air permeability is mostly carried out on samples, which are not exposed (before or during the tests) to any certain external loads, which could cause microcracks in hardened cement matrix. However, in the case of real structures there is always some stress level and thus the concrete permeability is usually affected by microcracks. To know both, permeability of sound concrete and the permeability of concrete containing certain amount of microcracks, is the basic assumption for correct evaluation of its durability. Our paper deals with the permeability of loaded specimens made of high performance fibre reinforced concrete (HPFRC). This type of concrete is in Slovakia used for the construction of containers for a low and medium level radioactive waste storage and thus their properties in loaded conditions are of primary concern. Permeability was measured with Torrent Permeability Tester on cube specimens at different loading levels and after unloading. Specimens were 10 years old and varied in the amount of fibre reinforcement.

Abstract: The properties of a multi-layered composite can be moulded through a selection of type, shape, and the number of layers of reinforcement material as well as powder fillers. Furthermore, the type and share of the matrix as well as the kind of hardeners also exert a significant influence on mechanical properties of composites. We attempted to experimentally establish the influence of the type of hardeners on mechanical properties. The test used Charpy’s hammer, and it was performed in the configuration of impact loading parallel to the edge. We prepared specimens of the materials. The specimens contained 12 layers of different fibre reinforcement: aramid (kevlar) fibre of 230 g/m² basis weight, glass fibre of 150 g /m2, and carbon fibre of 160 g/m² basis weight. The base was epoxy resin – Epidian 52, which was cured at room temperature by means of the following curing agents: PAC, TFF or Z-1, manufactured by Z. Ch. Organika-Sarzyna S.A. in Nowa Sarzyna. The experiments proved the tremendous influence of the type of the hardeners on toughness KC. It can be increased even by 25% for glass fibre reinforcement, about 20% for carbon fibre reinforcement and about 10% for aramid fibre reinforcement due to the use of an appropriate type of hardener.

Abstract: Strain-hardening cement-based composites (SHCC) resist increased tensile stress after first crack formation, over a significant range of tensile strain. This increased strength and strain capacity is achieved by effective crack bridging by fibres, across multiple cracks of widths in the micro-range. Whether the crack width limitation translates into increased durability through retardation of ingress of moisture, gas and other deleterious matter, is scrutinised in this paper. The potential of the comparatively new composite material becomes obvious, yet it is clearly outlined that further research is necessary before we fully understand the basic mechanisms underlying durability of SHCC.

Abstract: This paper describes the dynamic response of sandstone masonry units bound with fibre-reinforced mortars comparing a Portland cement-lime system with hydraulic lime. A drop-weight impact machine was used to generate stress rates up to 10⁷ kPa/s. The dynamic impact factor and stress rate sensitivity were evaluated for the flexural strength of the sandstone and mortar, and for the bond strength of the unit, and further, the pattern of failure was noted in the units for each mortar mix and loading rate. Polypropylene microfibres were incorporated at 0%, 0.25% and 0.5% volume fraction into the mortar. Results show that the flexural bond strength was more sensitive to stress rate than the flexural strength of the mortar, at similar rates of loading. Further, the stress rate sensitivity of the bond strength decreased with an increase in the fibre content. Also, whereas the flexural toughness factors for the stone-mortar bond fell with fibre reinforcement in the stronger Portland cement-lime system, the bond improved with fibre addition when employing hydraulic lime mortar.

Abstract: The aim of this work is to assess the feasibility of using polymer mortars reinforced with untreated natural fibres instead of artificial ones, for applications requiring highly alkali resistant materials, such as tanks and drainage systems for wastewater treatment plants. For this purpose, several formulations of polyester polymer mortars reinforced with different contents of jute and piassava natural fibres were investigated. Flexural and compressive behaviour, before and after exposure to a strong alkaline solution was analysed and quantified. Test results highlighted the high potential of these materials as basis construction material for precast applications requiring specific resistance under alkaline environments.

Abstract: Today heat resistant cast steels are the nominal solution for Ti-SPF forming die manufacturing. Nevertheless, this materials present some drawbacks related to delivery time and cost. A fibre reinforced refractory castable (FRRC) is proposed as a new solution for prototype SPF die manufacturing. Due to the general brittleness of refractory castables, a short fibre reinforcement has been investigated in order to avoid catastrophic failure during the forming process. General macroscopic behavior of such materials is very complex and presents large evolutions with the testing temperature. The paper addresses the important benefits of the reinforcement for refractory castable in the case of loading on a complex structure. The capability of the material to support several cracks is shown in the case of a technological sample with a complex shape.