Life cycle assessment of concrete incorporating all concrete recycling products

Abstract

This study evaluates the environmental impact of concrete incorporating locally available raw materials through life cycle assessment (LCA). It explores the integration of all concrete recycling products in the concrete mixes, including recycled concrete aggregates (coarse and fine) as alternative aggregates and ternary blended cements made with recycled concrete powder and waste perlite powder. With the declining availability of conventional supplementary cementitious materials like fly ash and blast furnace slag, alternative resources are essential. The developed concrete mixes reduced the climate change impact by up to 12% when ternary blended cements were used instead of ordinary Portland cement with the same aggregate mix. This can be attributed to the utilisation of industrial waste in the binder, which are locally available without any environmental burden other than transportation. The study maintains the same workability class and assesses the competitiveness of the developed mixes across strength classes, with notable environmental benefits recognised for the C50/60 strength class. A comprehensive assessment of the life cycle inventory (LCI) of the raw materials revealed significant variability between different sources for recycled aggregates, demonstrating the necessity for adopting a range of LCI data for alternative raw materials in the absence of specific data. Transparent reporting of production and transportation data is essential to improving LCA accuracy. The study shows the feasibility of developing circular concrete mixes that incorporate all products from the concrete recycling process, highlighting that optimising material performance and reducing reliance on conventional materials are crucial for increasing their attractiveness to the construction industry.