Carbonation for enhancement of fine recycled aggregate applied to mortar

Abstract

Some of the challenges faced by the construction industry related to sustainability are the generation of construction and demolition waste (CDW), environmental impacts caused by the demand for natural aggregates, and associated carbon (CO₂) emissions. One potential solution is recycling CDW as recycled aggregates (RA). Though, RA generally performs poorly compared to natural aggregates (NA) in concretes. Researchers suggest that CO₂ curing via accelerated carbonation may improve the properties of RA. However, further investigation is needed to understand the impact of CO₂ curing on mortar made with fine recycled aggregates (FRA). This study explores the effects of CO₂ curing on FRA under three different moisture content conditions (0 %, 30 %, and 50 %) in combination with accelerated carbonation. The CO₂ curing was then tested in five mortar mixes: 0 % RA, 50 % FRA, 100 %FRA, 50 % CO₂-cured FRA, and 100 % CO₂-cured FRA. The aggregate physical properties were analysed while CO₂ curing was assessed through mass gain, differential thermogravimetric analysis, X-ray diffraction, and Fourier-transform infrared spectroscopy. The mortar mix performance was evaluated through physical, mechanical and durability properties. The results revealed the 30 % moisture condition produced the highest carbonation results, leading to a reduction in FRA porosity. Also, mortars with CO₂-cured FRA demonstrated better overall performance compared to non-carbonated RA, and in some cases even outperformed mortars made with NA. These findings suggest that CO₂ curing could be an effective strategy to enhance the properties of FRA, expanding their potential applications in the construction industry.