How much cement can we do without? Lessons from cement material flows in the UK

Cement manufacture is responsible for 5–7% of world CO₂ emissions. Cement is primarily used in concrete, the most used material on the planet and a critical part of any analysis of emissions reduction strategy. To estimate the potential for reducing demand, this work analyses material flow in the cement industry, using the UK in 2014 as a case study. Combining published data, analytic assumptions, and interviews we estimated the material flow of cement from the production to a breakdown of its use in applications. Having broken down the demand for cement into 25 applications, multiple material efficiency techniques were considered: substituting cement for calcined clay and limestone, reducing the cement content of concrete, post-tensioning floor slabs, using more precast building elements, reducing construction waste, and reducing the overdesign in construction. We produce a final estimate of the total reduction in emissions achievable from material efficiency: 51.3%. Due to overlap and interactions between the methods, the attribution of the carbon abatement depends on the sequence of application. In this analysis, we have applied the reduction of overdesign last, because it is independent of the others, and would require a cultural change. We show then that cement demand from floors, repairs and maintenance, concrete beams, and applications within the transport sector should be targeted. The substitution of cement with calcined clay and limestone has the biggest potential to reduce cement demand (27%) and carbon emissions in the UK. Reducing the amount of cement in concrete has the next highest potential (10%), followed by post-tensioning floor slabs (3%).