Carbon dioxide upcycling into industrially produced concrete blocks

A novel carbon utilization trial produced carbon dioxide treated concrete blocks by adding carbon dioxide gas to the concrete during the mixing and forming stages of the block production. The gas was supplied at up to 1.5% by weight of cement. The carbon dioxide was absorbed into the concrete with an average efficiency of about 88% of the gas delivered. The carbon dioxide was shown to reduce the block compaction (and thereby the density) but increasing the mix water was an effective countermeasure. The carbonation process was shown to increase compressive strength (13-33% at ages from 7 to 56 days) and decrease absorption (by 18-36%). The CO2 upcycling reduced the carbon footprint of the blocks by 1.4% thereby demonstrating a simple approach to utilizing carbon dioxide to make useful construction materials. (C) 2016 Elsevier Ltd. All rights reserved.