Comparative life cycle assessment between imported and recovered fly ash for blended cement concrete in the UK

Abstract

A UK government report released in 2017 indicated that fly ash (FA) production locally is expected to seize after 2021. This means that for the construction industry to meet its continuously increasing demand for an Ordinary Portland Cement (OPC) replacement, FA would probably need to be either imported or recovered from landfills through energy-intensive processes. Recent reports show that companies in the UK have already started importing FA from several countries from which Germany and China were chosen as case studies to exemplify the closest and furthest respectively. The environmental impact associated with the FA transportation raises concerns about the environmental sustainability of the final concrete product. Therefore, this study focuses on using a life cycle assessment (LCA) tool to analyse the environmental impact of importing FA from Germany and China and compare that to recovering landfilled FA in the UK. The study is the first of its kind to investigate the environmental impact of any of the alternatives. Using a Cradle-to-Gate approach and a mix of primary and secondary data, these alternatives were modelled and compared to conventional OPC and currently available locally sources of FA. Results show that the environmental burden from transporting FA from China to the UK will overcome the environmental benefits of it replacing OPC. It is then concluded that the most promising alternative for cleaner production of blended cement concrete is to recover the 50 million tonnes of landfilled FA from the UK using the Dry-processing technique explained in the study. The second best alternative is to import FA from a country within the Europe region to the UK.

Mechanical properties and environmental performance of seawater sea-sand self-compacting Concrete

“…That shows that increasing the curing temperature is not a worthwhile technique for saving cement in civil engineering. In fact, this numerical result is easy to understand: the concrete’s strength is being improved by a more dense micro-structure (Hafez et al, 2020b). Adding more cement can quickly increase the hydration; high temperature curing, however, just accelerates the hydration.…”

A Systematic Review of the Discrepancies in Life Cycle Assessments of Green Concrete

“…While examining a sample of the papers being reviewed, it was apparent, as seen in Table 6, that the transportation distances vary widely between the different studies. A study by Panesar et al [95] concluded that the critical distance for importing FA that would still yield a BCC mix with a positive overall environmental impact profile compared to OPCC is around 900 km as opposed to the 3000 km proposed by Hafez et al [160] and 5700 km by O'brien et al [96]. Additionally, Turk et al [13] argue that if the recycled aggregates are sourced from a landfill that is more than 230 km from the concrete batch plant, the RAC produced would have a higher environmental impact compared to OPCC, which is a larger figure than the 145 km concluded by Anastasiou et al [53].…”

An Application of Artificial Neural Network to Predict the Compressive Strength of Concrete using Fly Ash and Stone Powder Waste Products in Central Vietnam

“…This research axis of using waste products has received significant attention in many countries. The mechanical properties of the concrete using these materials have been considered in literature [4,5] and the compressive strength was also studied by Kanthe et al [6] and Sadowski et al [7]. Therefore, it helps to benefit waste products and limit the use of traditional materials, helping to reduce adverse effects on the natural environment [8,9].…”