Cost and Environmental Benefits of Using Macro Plastic Fibres
In recent years, macro plastic fibres have become an attractive alternative to traditional steel reinforcement in construction industry due to multiple reasons. Firstly, plastic fibres have significantly low cost compared to steel. For instance, based on our previous study (Yin et al. 2015a), 100 m2 of concrete footpath (100 mm thick) typically requires seven sheets of SL82 steel mesh (364 kg of total weight). Whereas, 40 kg of plastic fibre (4 kg/m3) can achieve the same degree of reinforcement in concrete footpath of same area. As of current price in Australia, the cost of 40 kg PP fibre is AU$600 (Fibercon 2015), while seven sheets of SL82 steel mesh cost AU$800 (OneSteel 2015). This shows the clear saving of price when using macro plastic fibres. Furthermore, preparation required when using steel mesh such as laying, cutting and tying requires considerable labour time and cost compared to the use of plastic fibres, which can be directly added to the agitator of an agitator truck and combined with the ready-mixed concrete. Ochi et al. (2007) reported that the process of using traditional steel reinforcement in a footpath of size 100 m2 and thickness of 150 mm includes steel mesh preparation, and concrete placing and finishing, which requires 20 worker-hours (i.e. 0.2 man-h/m2). However, the PP fibres can be directly mixed with concrete, eliminating the need of preparation of steel, which significantly reduces worker-hours to 10 h, (i.e. 0.1 man-h/m2).
Thirdly, steel is highly corrosive in nature; corrosion of steel reinforcement in concrete structures can lead to their deterioration and failure. However, plastic fibres, especially PP fibres, as we discussed before, are highly resistant to corrosion, thus having a long-term durability. Moreover, handling plastic fibres are much safer and lighter than using steel.
Last but not least, the production of plastic fibres can significantly reduce carbon footprint compared to that of producing steel. For instance, producing 40 kg of PP fibre can emit 140 kg carbon dioxide equivalents (Shen et al. 2010), while the production of 364 kg of steel has a 1250 kg of carbon emissions (Strezov and Herbertson 2006).