Decarbonising Precast Concrete Manufacturing: Implementation of Low-Carbon Concretes

Abstract

The greatest challenge of the modern construction industry is posed by the global climate emergency. The shift towards modern methods of construction, adopting an off-site manufacturing approach, and minimising in-situ work can help create a more sustainable future, by improving working conditions, quality, and efficiency. Advances in low-carbon technologies, suitable for precast concrete industry, are crucial for meeting net-zero goals. Aiming to drive innovation in the area, Laing O’Rourke, an international engineering and construction company, led a collaborative project with academic partners, University of Cambridge Centre of Industrial Sustainability and University of Sheffield Advanced Manufacturing Research Centre. The Decarbonising Precast Concrete Manufacturing (DPCM) project is a part Innovate UK funded R&D project that aspired to deliver a feasibility study for implementing decarbonisation interventions at Laing O’Rourke’s precast concrete factory. This paper presents part of the findings of the DPCM project focused on the deployment of low-carbon concretes. Technical background review of available and emerging materials informed the selection of geopolymer concrete, alkali-activated cementitious material (AACM), high GGBS replacement mixes, calcium sulfoaluminate (CSA) cement concrete and limestone cement concrete for further testing. All mixes have been subjected to laboratory trials to assess fresh and hardened concrete properties. Out of these, geopolymer concrete, AACM and high GGBS mix were progressed to batching and manufacturing trials at Laing O'Rourke’s precast concrete facility, which included production of full-scale precast concrete units, using the low-carbon mixes. The trials validated feasibility of integrating low-carbon mixes into a precast concrete manufacturing facility and identified the associated challenges, in particular slower strength gain, consistency, and open life. The impact of these properties on production throughput in the precast factory can be significant; thus mix selection, alternative curing and lifting strategies, and simulation-based production planning tools may be needed for use of low-carbon concretes at project or multi-project scale implementation.