Concrete reinforced with macro fibres recycled from waste GFRP

Fibre reinforced polymer (FRP) composites are widely used in many industries due to their excellent mechanical and durability properties. This means that an increasing amount of FRP waste, arising from production, processing and decommissioning, needs to be processed. Common FRP composites are normally thermoset and non-biodegradable, posing a significant environmental threat if they are not disposed of properly at their end of life. While recycling of FRP is environmentally desirable, almost all existing recycling methods, which are based on either thermal, chemical or mechanical processes, are economically unviable if governmental subsides are not available. The recycling of glass FRP (GFRP) waste, which accounts for over 95% of all types of FRP waste by weight, is even more economically challenging than the recycling of carbon FRP (CFRP) waste due to the lesser economic value of the former. This paper explores a novel mechanical method for recycling GFRP waste by processing it into macro fibres for reinforcing concrete, with the resulting material referred to as macro fibre reinforced concrete (MFRC). The mechanical properties of MFRC were investigated. The test results showed that the addition of macro fibres had two major effects on the concrete: (1) the workability of concrete depends strongly on the macro fibre volume ratio, with the slump value reducing from 176 mm to 83 mm as the macro fibre volume ratio increased from 0% to 1.5%; (2) the flexural strength and toughness of the concrete be greatly enhanced by the addition of macro fibres, e.g., by 1.3 and 230 times when the macro fire value ratio was 1.5%. The proposed recycling method for waste GFRP is therefore believed to be both technically feasible and economically attractive.