Behaviour of concrete building units incorporating waste plastic eco-aggregate (RESIN8) subjected to fire conditions

Plastic waste has started to be incorporated within construction systems with potential benefits including improved sustainability, decreased costs, lighter construction units and enhanced thermal performance. However, the addition of plastics has an unknown impact on the fire response and associated behaviour of recycled construction products. Hence, this work seeks to answer the question: does the incorporation of waste plastic in masonry systems influence fire risk? This study investigates the effect of using the RESIN8 eco-aggregate in bricks, an aggregate based on processed waste plastic. This is done by exposing concrete bricks containing 0%, 5%, 10%, 20%, 30%, 40% and 50% RESIN8 by volume to a heat flux of 30 kW/m2 for an hour. The replacement content of the RESIN8 samples influenced both smoke production and mass loss rates, with high volumes of smoke observed for the highest replacement content of RESIN8. The capacity of the RESIN8 brick units was also found to drop by up to 34.7% of the original compressive strength. It is shown that low replacement rates (e.g. 5 and 10%) are unlikely to affect fire risk significantly, but higher replacement rates may be a concern due to smoke production and heat release rates. •Recycled waste plastic (RESIN8) coarse aggregate used in concrete masonry units.•High intensity radiation used to study the fire behaviour of the units.•Compressive strength, post-fire strength and mass loss investigated.•High plastic content can lead to smoke emissions and higher heat release rates.•RESIN8 replacement level recommended to be limited to 10%.