A comparative life cycle assessment of recycling waste concrete powder into CO2-Capture products

Ekaterina Kravchenko; Meike Sauerwein; Svetlana Besklubova; Charles Wang Wai Ng

doi:10.1016/j.jenvman.2023.119947

A comparative life cycle assessment of recycling waste concrete powder into CO₂-Capture products

J Environ Manage. 2024 Feb 14:352:119947. doi: 10.1016/j.jenvman.2023.119947. Epub 2024 Jan 9.

Authors

Ekaterina Kravchenko¹, Meike Sauerwein², Svetlana Besklubova³, Charles Wang Wai Ng⁴

Affiliations

¹ Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong Special Administrative Region of China. Electronic address: kravchenko@ust.hk.
² Division of Environment and Sustainability, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong Special Administrative Region of China. Electronic address: meike@ust.hk.
³ Department of Industrial and Manufacturing Systems Engineering, The University of Hong Kong, Pok Fu Lam, Hong Kong Special Administrative Region of China. Electronic address: lanabess@hku.hk.
⁴ Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong Special Administrative Region of China. Electronic address: cecwwng@ust.hk.

PMID: 38198842
DOI: 10.1016/j.jenvman.2023.119947

Abstract

Waste concrete powder (WCP), a byproduct of construction and demolition (C&D), currently has a low degree of recycling despite its potential for environmentally friendly applications. WCP can serve as a valuable substitute for cement, offering advantages for resource conservation and carbon sequestration. However, there are very few studies that quantitatively assess the environmental impact of incorporating WCP into the circular economy as a secondary material instead of disposing of it. The energy-intensive processing of WCP raises questions about the optimal carbonation time using available equipment. This study aims to fill this knowledge gap by employing carbon footprint and life cycle assessments (LCA) to optimize WCP recycling. Three recycling WCP scenarios are analyzed. The first scenario involved the conversion of WCP into compacts that absorb CO₂ during the carbonation process. The results of the first scenario revealed that the optimal carbonation time for WCP compacts was 8 h, during which 42.7 kg CO₂-e per tonne of WCP compacts was sequestered. The total global warming potential (GWP) was -4.22 kgCO₂-e, indicating a carbon-negative recycling process. In the second and third scenarios, LCA was conducted to compare the use of carbonated and uncarbonated WCP as a partial replacement for cement in concrete. In these scenarios, it was found that uncarbonated WCP is a more effective solution for reducing the carbon footprint of traditional concrete mixes, achieving a significant 16% reduction of GWP when 20% of cement is replaced. Conversely, using carbonated WCP as a partial cement replacement in concrete mixtures shows limited potential for CO₂ uptake. The sensitivity analysis reveals that the carbon footprint of the WCP compacts production process is strongly influenced by the electricity supplier used.

Keywords: Carbon dioxide emission; Carbon footprint; Environmental impact; Life cycle assessment; Waste concrete powder.

MeSH terms

Animals
Carbon Dioxide*
Carbon Footprint
Carbonates
Construction Materials*
Life Cycle Stages
Powders
Recycling / methods

Substances

Carbon Dioxide
Powders
Carbonates