Influence of Aramid-Polyolefin Fibers on the Properties of Bituminous Mixtures

The use of additives in bituminous mixtures such as fibers has been the subject of various studies. Different fibres including cellulose fibres, steel fibres, basalt fibres, glass fibres and aramid fibres can be used to improve the properties of bituminous mixtures. Depending on the type of fibres used, different characteristics can be changed. The paper contains results of comparative tests of bituminous mixtures with aramid-polyolefin fibres. Asphalt concrete used for wearing course with maximum aggregate size of 11 mm was evaluated in the study. Reference mix with an average penetration grade of 50/70 was chosen as a base for modifications. Due to difficulty in preparing mixtures with fibers in a laboratory mixer, test specimens were obtained from a stationary plant. The fibers and aggregate mix was prepared before adding the asphalt. The fibers were added at a rate of 0.5 kg per 1000 kg of finished bituminous mixture. This allowed to obtain an even distribution of fibers in the mixture resulting in a homogeneity necessary for planned tests. This allowed to omit the scale effect, that could occur due to differences between laboratory and stationary mixing. Stiffness modulus tests were performed using the IT-CY (Indirect Tension to Cylindrical Specimens) method for a wide temperature range of 0-30°C. The specimen resistance to permanent deformation was evaluated. Obtained results has shown a clear increase in the resistance to permanent deformation of mixtures with aramid- polyolefin fibers, which is especially important for mixtures used for wearing course. The results has also shown a significant increase in the stiffness modulus regardless of temperature range. Results of conducted experiments has shown that it is possible to reduce the thickness of bituminous overlay in case of reinforcement of the existing pavement structure. The analysis of results has shown that the application of aramid-polyolefin fibres in bituminous mixtures can improve the functional features of the pavement and be beneficial to the investors.

Experimental verification of high-strength composite materials using a simulation program

The use of composites in engineering applications has been steadily growing in recent years. Despite this growth and despite some important advantages of the properties that composites offer, such as reduced weight, design freedom, etc., a breakthrough in high- volume components in engineering applications has not been achieved at present. Therefore, when designing selected parts and structures using new materials, such as composites, material and manufacturing costs must be considered a high priority if further significant growth is achieved. However, many other factors must also be considered when designing a composite part for engineering use. These factors also depend on the particular material or combination of materials being evaluated. The paper is focused on testing a composite material manufactured from polybutylene terephthalate (PBT), reinforced with high-strength fibres Cordenka and Aramid fibres. The composite material's mechanical properties were verified using Ansys simulation software.

Fibre-Reinforced Foamed Concretes: A Review

Foamed concrete (FC) is a high-quality building material with densities from 300 to 1850 kg/m3, which can have potential use in civil engineering, both as insulation from heat and sound, and for load-bearing structures. However, due to the nature of the cement material and its high porosity, FC is very weak in withstanding tensile loads; therefore, it often cracks in a plastic state, during shrinkage while drying, and also in a solid state. This paper is the first comprehensive review of the use of man-made and natural fibres to produce fibre-reinforced foamed concrete (FRFC). For this purpose, various foaming agents, fibres and other components that can serve as a basis for FRFC are reviewed and discussed in detail. Several factors have been found to affect the mechanical properties of FRFC, namely: fresh and hardened densities, particle size distribution, percentage of pozzolanic material used and volume of chemical foam agent. It was found that the rheological properties of the FRFC mix are influenced by the properties of both fibres and foam; therefore, it is necessary to apply an additional dosage of a foam agent to enhance the adhesion and cohesion between the foam agent and the cementitious filler in comparison with materials without fibres. Various types of fibres allow the reduction of by autogenous shrinkage a factor of 1.2–1.8 and drying shrinkage by a factor of 1.3–1.8. Incorporation of fibres leads to only a slight increase in the compressive strength of foamed concrete; however, it can significantly improve the flexural strength (up to 4 times), tensile strength (up to 3 times) and impact strength (up to 6 times). At the same time, the addition of fibres leads to practically no change in the heat and sound insulation characteristics of foamed concrete and this is basically depended on the type of fibres used such as Nylon and aramid fibres. Thus, FRFC having the presented set of properties has applications in various areas of construction, both in the construction of load-bearing and enclosing structures.

Experimental Research on the Hysteretic Behaviour of Pressurized Artificial Muscles Made from Elastomers with Aramid Fibre Insertions

Inherent hysteresis behaviour of pressurized artificial muscles is complicated to understand and handle, calling for experimental research that allows the modelling of this phenomenon. The paper presents the results of the experimental study of the hysteretic behaviour of a small-size pneumatic muscle. The specific hysteresis loops were revealed by isotonic and isometric tests. Starting from hypothesis according to that the tube used for the pneumatic muscle is made entirely of aramid fibres enveloped by an elastomer material that merely ensures their airtightness, the paper presents the hysteresis curves that describe the radial and axial dimensional modifications as well as the variation of the developed forces for different feed pressures. The obtained third-degree polynomial equations underlie the configuration of high-performance positioning systems.

Assessment of Impact of Aramid Fibre Addition on the Mechanical Properties of Selected Asphalt Mixtures

Various additives to asphalt binders and asphalt mixtures improving their properties are being used more and more frequently in order to improve the durability of road pavements. Such additives include various types of fibres, including aramid fibres. Tests concerning the impact of aramid fibre addition on the properties of selected asphalt mixtures have been described herein. Two types of asphalt mixtures were assessed: high modulus asphalt concrete (HMAC) and stone mastic asphalt (SMA). The examined asphalt mixtures were assessed with regard to: resistance to rutting, resistance to water and frost as well as fatigue resistance. The conducted tests showed relatively small impact of aramid fibre addition on the improvement of some assessed properties of the analysed asphalt mixtures. The obtained results were also compared to results of the tests conducted by the other research team concerning the impact of aramid fibre addition on the properties of the other types of asphalt mixtures.

The influence of kenaf contents and stacking sequence on drop-weight impact properties of hybrid laminated composites reinforced polyvinyl butyral composites

For the high cost of aramid fibres and the necessity for finding alternatives which are environmentally friendly, a portion of aramid was substituted by woven kenaf at various sequences and thicknesses, to identify the proper arrangement for producing helmet shell. Drop-weight impact tests were conducted on different configurations of 19 layers of kenaf and aramid reinforced polyvinyl butyral film, which were fabricated by the hot press method. Effects of fibre content, layering sequence and energy absorption of the laminated composites were studied at three different impact energies 50, 75, 100 J. Results suggested that the behaviour of hybrid laminates has a positive effect in terms of energy absorbed and impact resistance, due to lower failure strain of kenaf fibres. Additionally, placing woven kenaf layers alternate with aramid layers provides higher impact loads and absorbed energy than placing woven kenaf and aramid separately, especially at impact level 100 J. For example, the absorbed energy of the 17 Aramid/2 Kenaf Alt. (H1A) is 72.99 J, while for 17 Aramid/2 Kenaf (H1) is 66.04 J. The closed curves indicated the success of the samples in absorbing the dissipated energy at various impact energies values. It could be deduced that it is possible to replace the aramid fibre in various composites industries by kenaf fibre, to minimize harmful environmental effects and cost of petroleum products.

Effects of resin pre-coating on interfacial bond strength and toughness of laminar CFRP with and without short aramid fibre toughening

The brittle adhesive layer in carbon fiber-reinforced polymer (CFRP) laminates was strengthened by using short aramid fibers in this study. To ensure the feasibility and effectiveness of short aramid fiber interfacial toughening at the interface between the carbon-fiber face sheets, the self-prepared short aramid fibre tissue and the wettability treatment technology with resin pre-coating were applied to enable short aramid fibres to be well embedded in the uneven regions in the CFRP fabrics with fibres oriented at 0° and 90° to form a strong pulling resistance. The ultimate load and the mode I interlaminar fracture toughness have been improved by 75% and 103.9% from the double cantilever beam mode I crack propagation tests, respectively. The reinforcing mechanisms within the “composite adhesive layer” as a result of short aramid fibres are discussed together with detailed scanning electron microscopy observations and comparison test results.

Mechanical Properties of Kevlar Fibre Reinforced with Banana Fibre and Aluminium Mesh using Epoxy Resin

Kevlar fibres are para aramid fibres rather than Meta-Aramid structure of Nomex. These fibres have high tensile strength, tensile modulus and heat resistance .Kevlar is about five times lighter than steel in terms of the same tensile strength. In fact, it is the strongest textile fibre available today. It is therefore used in Radial tyres, Conveyor belts, Aircraft parts and mainly used in Ballistics and Frictional products. The aim of this investigation is to increase the mechanical properties of composite material of Kevlar fibre. The Kevlar fibre is reinforced with the banana fibre,which is a Natural Fibre and Aluminium Mesh using Epoxy resin. The Mechanical Properties of Newly formed Composite material using Kevlar Fibre is improved and find its application in a higher position while comparing to the Kevlar Fibre