Use of macro plastic fibres to reinforce concrete has attracted widespread attention from both scientists and construction industry due to the multiple sustainability benefits they offer, compared to steel fibres and steel reinforcing mesh. This paper critically reviews the current state of knowledge and technology of using macro plastic fibres to reinforce concrete. Detailed review on the various preparation techniques and the resulting properties of macro plastic fibres are presented and the effects of macro plastic fibres on the fresh and hardened concrete properties are discussed in this paper. The effect of macro plastic fibres on workability, plastic shrinkage, compressive strength, splitting tensile strength, flexural strength, post-crack performance and dry shrinkage is discussed in this paper. Pull-out behaviour and degradation behaviour of the fibre in the concrete are also reviewed. Finally, cost and environmental analysis and some applications of the plastic fibre reinforced concrete are discussed

Efficient technology and applications for recycled polymer waste has become increasingly important to decrease environmental contamination and to conserve nonrenewable fossil fuels. Mechanical recycling is the most widely practiced in Australia, since it is relatively easy and economic; and moreover, infrastructure for collection and reprocessing has been well established. In order to improve quality of end products of recycled plastics, various workable reprocessing techniques in the second stage of mechanical recycling have been developed and widely applied in the recycling industry. This article critically reviews the current reprocessing techniques of recycled polyolefins. Reprocessing recycled polyolefins is always accompanied with degradation, crystallization, and consequent processability problems, which result from molecular chain scission, branching, and crosslinking. The present state of knowledge and technology of various reprocessing techniques, including melt blending, filler reinforcement and mechanochemistry, is then described and evaluated systematically. Each reprocessing technique presents its own individual advantages and special applications. POLYM. ENG. SCI., 55:2899–2909, 2015. © 2015 Society of Plastics Engineers

This study assesses the environmental impact of four alternatives for reinforcing 100 m² of concrete footpath (Functional Unit, FU) by using cradle to gate life cycle assessment (LCA), based on the Australian context. Specifically, the four options considered are a) producing steel reinforcing mesh (SRM), b)producing virgin polypropylene (PP) fibre, c) recycling industrial PP waste and d) recycling domestic PP waste. The FU yields 364 kg of SRM (in a) and 40 kg of PP fibres (in b, c and d), necessary to achieve the same degree of reinforcing in concrete. All the activities required to produce these materials are considered in the study, namely manufacturing and transportation, and also recycling and reprocessing in the case of industrial and domestic recycled PP waste fibres. These processes are individually analysed and quantified in terms of material consumption, water use, and emissions into the environment. This allows for the impacts from producing recycled fibres to be compared with those from producing virgin PP fibre and SRM, which are traditionally used. The LCA results show that industrial recycled PP fibre offers important environmental benefits over virgin PP fibre. Specifically, the industrial recycled PP fibrecan save 50% of CO₂ equivalent, 65% of PO₄ equivalent, 29% of water and 78% of oil equivalent, compared to the virgin PP fibre. When compared to the SRM, the industrial recycled PP fibre can save 93% of CO₂ equivalent, 97% of PO₄ equivalent, 99% of water and 91% of oil equivalent. The domestic recycled PP fibre also generates reduced environmental impacts compared to virgin PP fibre, except for higher consumption of water associated with the washing processes

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 construction industries has not yet been seen due to limited data available on their durability, mechanical properties and performance in concrete. This paper reports findings from a laboratory study on the alkali resistance and performance of recycled polypropylene (PP) fibres in the 25 MPa and 40 MPa concretes, used for footpaths and precast panels, respectively. The recycled PP fibre was proven to have very good alkali 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. Since 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 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