Mechanical Performance of Fiber Reinforced Cement Composites Including Fully-Recycled Plastic Fibers (original) (raw)
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Comparative evaluation of virgin and recycled polypropylene fibre reinforced concrete
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Use of macro recycled plastic fibres in reinforcing concrete footpaths and precast panels offers significant economic and environmental benefits over traditionally used virgin plastic fibres or steel fibre and mesh. However, wide adoption of recycled plastic fibres by the construction industries has not yet been seen due to limited data available on their durability, mechanical properties and performance in concrete. This paper reports the findings from a laboratory study on the alkaline resistance and performance of recycled polypropylene (PP) fibres in 25 MPa and 40 MPa concrete, used for footpaths and precast panels, respectively. The recycled PP fibre was found to have lower tensile strength but higher Young's modulus than those of virgin PP fibre. The recycled PP fibre was proven to have very good alkaline resistance in the concrete and other alkaline environments. The recycled PP fibre showed excellent post-cracking performance in concrete, bringing in significant ductility. In the 40 MPa concrete the effectiveness of reinforcement of PP fibres depended on their Young's modulus and tensile strength in the crack mouth opening displacement (CMOD) test. Therefore, the recycled PP fibre produced similar or slightly lower reinforcement than that of virgin PP fibre. In the 25 MPa concrete, the Young's modulus of fibres was more effective on their reinforcement than the tensile strength, thus the recycled PP fibre produced better reinforcement than that of virgin PP fibre.
The Use of Recycled Polymer Fibers as Secondary Reinforcement in Concrete Structures
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This paper presents the results of a feasibility study undertaken to identify the potential for using recycled high-density polyethylene (RHDPE) fiber as secondary reinforcement in Portland cement concrete structures. This study demonstrated that: 1) It is feasible to use recycled high density polyethylene fibers as secondary reinforcement for temperature and shrinkage influences in Portland cement concrete structures, 2) RHDPE fibers appear to be able to be produced more economically than virgin polypropylene fibers, 3) RHDPE fibers appear to overcome several of the negatives presented by the virgin polypropylene fibers, including floating to the surface and impact on slump, and 4) Shrinkage crack propagation was controlled as effectively by the RHDPE fibers as by the virgin polypropylene fibers. Four very important concerns relative to the use of RHDPE that were reserved for later study subject to the success of this study are: 1) the potential challenge of the alkaline reaction of the RHDPE material, 2) RHPD's performance under extreme temperature cycling, water migration rate studies, 3) its performance under extreme temperature cycling, and 4) the impact of long-term plastic shrinkage.
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Journal of Applied Polymer Science, 2015
Polypropylene (PP) fibers have been widely used to reinforce concrete footpaths as an alternative to steel mesh. The reinforcing effect of the PP fiber is directly proportional to its tensile strength and Young modulus. This research explored the feasibility of using an improved melt spinning and hot drawing process to produce virgin and recycled PP fibers of high mechanical properties in an industrial scale. Commercial grade granules of virgin PP, recycled PP and HPDE were mixed in different proportions in preparing five different types of fibers. All the fibers obtained high tensile strength and Young modulus. A relationship between the structural parameters and mechanical properties was then established. It was observed that the melt spinning and hot drawing process formed both a-form and b-form crystals in the PP fibers, and significantly improved crystallinity from about 50% to 80%.
Mechanical properties of recycled plastic fibres for reinforcing concrete
With the increase in the general awareness of waste management, recycled plastic fibre reinforced concrete has attracted widespread attention. However, the production of recycled plastic with sufficient mechanical properties is still a major challenge. This research focuses on improving the tensile strength and Young's modulus of recycled polypropylene (PP) fibres produced through a hot drawing process. The mechanical properties of the mixture of 50 % recycled PP and 50 % virgin PP were compared with 100 % virgin and 100 % recycled plastic fibres. The 100 % recycled PP fibres achieved tensile strength of 310 MPa and Young's modulus of 620 MPa. The combination of recycled (50 %) and virgin PP (50 %) showed significant improvement in Young's modulus (800 MPa). Tensile strength was found to increase to 360 MPa.
Utilizing recycled polypropylene fibres as reinforcement for concrete beams
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Polypropylene (PP) fibers are among numerous plastic waste materials, which are generated by the different industrial and domestic activities. Due to its low biodegradability, plastic waste constitutes a real environmental problem. The valorization of recycled PP fibers in the fabrication of concrete is one of the efficient solutions to cater for the environmental problems induced by plastic waste. In this experimental work, the workability and the mechanical properties of concrete are examined with different content ratios of recycled PP fibers. The mechanical behavior and the failure mode of concrete beams reinforced with recycled PP fibers are also studied. The used PP fibers are recycled from plastic waste of PLAST BROS factory in BordjBouArreridj, in Algeria. The fiber’s diameter varies between 0.7 and 0.9mm. The various fiber content ratios tested in this investigation are 0.25, 0.5 and 1%. Based on the results of this study, the presence of recycled PP fibers in concrete decr...
Materials, 2020
High-performance concrete has low tensile strength and brittle failure. In order to improve these properties of unreinforced concrete, the effects of adding recycled polypropylene fibers on the mechanical properties of concrete were investigated. The polypropylene fibers used were made from recycled plastic packaging for environmental reasons (long degradation time). The compressive, flexural and split tensile strengths after 1, 7, 14 and 28 days were tested. Moreover, the initial and final binding times were determined. This experimental work has included three different contents (0.5, 1.0 and 1.5 wt.% of cement) for two types of recycled polypropylene fibers. The addition of fibers improves the properties of concrete. The highest values of mechanical properties were obtained for concrete with 1.0% of polypropylene fibers for each type of fiber. The obtained effect of an increase in mechanical properties with the addition of recycled fibers compared to unreinforced concrete is unexpected and unparalleled for polypropylene fiber-reinforced concrete (69.7% and 39.4% increase in compressive strength for green polypropylene fiber (PPG) and white polypropylene fiber (PPW) respectively, 276.0% and 162.4% increase in flexural strength for PPG and PPW respectively, and 269.4% and 254.2% increase in split tensile strength for PPG and PPW respectively).
Recycled Polyethylene Fibres for Structural Concrete
Applied Sciences, 2022
Modern society demands more sustainable and economical construction elements. One of the available options for manufacturing this type of element is the valorisation of end-of-life waste, such as, for example, the recycling of polymers used in industry. The valorisation of these wastes reduces costs and avoids the pollution generated by their landfill disposal. With the aim of helping to obtain this type of material, this work describes a methodology for recycling polyethylene for the manufacture of fibres that will later be used as reinforcement for structural concrete. These fibres are manufactured using an injection moulding machine. Subsequently, their physical and mechanical properties are measured and compared with those of the material before it is crushed and injected. The aim of this comparison is to evaluate the recycling process and analyse the reduction of the physical-mechanical properties of the recycled polyethylene in the process. Finally, to determine the properties...
Applied Sciences, 2021
The incorporation of natural or recycled fibers in concrete represents a field for improvement in this structural material and a step towards sustainability. The objective of this research is to determine whether the addition of recycled carbon fibers (CFRP), which have been hardened using epoxy resin, improves the behavior of concrete and whether its performance is comparable to that achieved by adding polypropylene fibers, which would result in a viable recycling alternative for this type of fiber. In order to explore this objective, 120 specimens were produced, on which compression, flexural, and impact tests were performed, and into which recycled CFRP fibers or polypropylene fibers were incorporated. By comparing the results obtained, it may be concluded that the addition of fibers substantially improves the ductility of the concrete and reduces the spalling effect when compared to concretes without added fibers. The concretes containing recycled CFRP fibers in quantities of 3 ...
This study evaluated Engineered Cementitious Composites (ECC) with polyvinyl alcohol (PVA), polypropylene (PP) or recycled polyester (POL) fibers inserted in a matrix with elevated silica fume content. Several PP (2.2-2.6%) and POL (2.3-2.7%) contents were tested and compared to a compound containing 2.0% PVA. Flexural bending strength tests, the bending rupture modulus, number and width of cracks and deformation were measured at 5 different curing ages (7, 14, 28, 56 e 84 days). The test results also showed that in the fresh state, ECCPVA2.0 presented the best result with an average spread of 255 mm, followed by ECCPP2.4 and ECCPOL2.3. All Γ values obtained confirmed that all composites attained plastic consistency. In the hardened state, composites with POL fibers had tensile strength performance similar to PVA fibers with regards to deformation, deflection, rupture modulus, average crack width and number of cracks. In addition, ECCPOL2.7 demonstrated mechanical properties superior to ECCPVA2.0. So, the use of 2.7% POL content resulted in strengths higher than the reference PVA compound and demonstrated the potential of POL fibers in ECC development at ages over 28 days. The use of recycled POL fibers, at a content of 2.7%, resulted in an increase in the ductility of the composite, reaching the values of ECC-PVA at 28 and 84 days. On the other hand, PP composites did not present the expected behavior of an ECC. More specifically, the matrix had high tensile strength, modulus of elasticity and tenacity, which limited crack formation and overloaded the reinforcement fibers. Thus, PP fibers were deemed incompatible for ECCs with rich matrices.