The replacement of wood or concrete in construction projects: An industrial case study demonstrating the benefits of intrusion moulded waste plastic

Abstract

Intrusion moulding technology can convert waste plastic into a strong, lightweight construction material, for use as an alternative to wood or concrete. Using a combination of published research, independent testing and an industrial case study to demonstrate the benefits, this chapter will propose that the construction industry should consider intrusion moulded waste plastic as a first choice construction material. Recycled waste plastic is particularly suitable in applications involving contact with earth and/or water as the material does not require chemical preservatives and is resistant to moisture, micro-biological attack and acid soil. From an international perspective, recycled plastic is an option in areas where wood is subject to termite attack and avoids the problems of salt weathering on concrete in the Middle East. A major benefit of intrusion moulding is the ability to create large cross-sectional and non-uniform shapes, which results in recycled plastic being used in applications as diverse as biofilter floors, underground utility chambers and drop kerbs. The robust nature of the intrusion moulding process also allows different polymers to be blended together in order to obtain the best combination of rigidity and flexibility for specific applications. The industrial case study refers to the Ecocrib retaining wall, which is manufactured using a blend of post-industrial waste plastics. Ecocrib has been certified by the British Board of Agrément to achieve a Design Service Life in excess of 120 years, which is similar to steel reinforced concrete crib walls and twice that of a wooden alternative; however, the recycled plastic does not require the marine transport or chemical preservatives of timber, whilst avoiding the CO2 emissions of concrete production. Moreover, the Ecocrib headers and stretchers are far lighter than the concrete alternatives, resulting in reduced cost of transport and installation. Yesterday’s waste can become tomorrow’s construction material.