Study on the Effect of Carbonation of Various Low Quality Recycled Fine Aggregates for Modification and Properties of Mortar

The use of recycled aggregate is desirable to realize a carbon-neutral and sustainable society. In addition, the widespread use of concrete using large amounts of recycled aggregate that can absorb CO2 will contribute to reducing the environmental impacts. The authors have proposed modification of recycled aggregate by accelerated carbonation technology, however it have not conducted many studies on the type of fine aggregate, which is considered to greatly affect the properties of concrete. Therefore, in this study, accelerated carbonation was performed using low-quality recycled aggregate with various properties to confirm its modification effect. As a result, it was confirmed that the finer the particle size, such as fine grains in the aggregate, the higher the adhered paste ratio, and thus the greater the CO2 absorption. In addition, the physical properties of the mortar using this carbonated aggregate were measured, and it was proven that the tendency of mortar improvement was higher when fine aggregate with a high modification rate was used. In addition, in the results of trying various modification methods, it became clear that the key point is to modify the fine particle in the aggregate.