Accelerated carbonation of fresh cement-based products containing recycled masonry aggregates for CO2 sequestration

Abstract

This study examines the effects of accelerated carbonation on the mechanical properties, dry bulk density, porosity accessible to water, and the CO2 sequestration capacity of a porous cement-based material that contains different replacement ratios of natural aggregate (NA) by recycled masonry aggregate (RMA). Two hardening environments were used: a conventional climate chamber as a reference (0.04 % CO2) and a climatic chamber for accelerated carbonation (5% CO2), with curing times of 1, 3, and 7 days. A volumetric substitution method where NA was replaced with RMA did not significantly affect its mechanical properties. Accelerated carbonation reduced the curing time, improved mechanical properties, increased dry bulk density, and decreased accessible porosity for water for all the mixes studied. The maximum CO2 sequestration for cement-based materials made with mixed recycled aggregates was 27 kg CO2/t of mix. Accelerated carbonation of fresh cement-based products containing RMA is a promising CO2 capture and utilisation technology for precast non-reinforced concrete product manufacturing.