Aqueous carbonation of recycled concrete wastes

Aqueous carbonation is a carbonation method that has attracted much interests because of its low energy cost, rapid carbonation rate, and low CO2 requirement. It has the potential to be upscaled because of enhanced performance. Here, we introduce this technique systematically including carbonation kinetics, phase evolution, microstructural development, and applications in new concrete. Recycled aggregates with different sizes (>2.36, 0.15–2.36, and <0.15 mm) are summarized separately. Based on previous research, all carbonated recycled aggregates possess high reactivity that enhances the interface zone between cement paste and aggregates. More important, fine recycled aggregates can be used to produce value-added products (nanosilica gel and aragonite whisker). More research is needed related to improving the carbonation rate, adding admixtures in solution, using a large particle size, and conducting pilot plant tests.