Effects of ethylenediamine tetra-acetic acid (EDTA) on the accelerated carbonation and properties of artificial steel slag aggregates

Artificial steel slag aggregates were prepared via accelerated carbonation with the assistance of EDTA. The influences of EDTA on the CO2 uptake, microstructure, and properties of the carbonated steel slag aggregates as well as the performance of concrete were investigated. With the addition of EDTA, the carbonation of steel slag aggregates was enhanced, yielding increases in CO2 uptake, quantity of formed CaCO3 and bulk density whereas reduction in the crushing value. Moreover, EDTA improved the volume stability of the steel slag aggregate. The EDTA played a role as a catalyst in the process of steel slag carbonation, which chelated the calcium leached from steel slag and hence accelerated the calcium leaching. This hence increased the carbonation efficiency and carbonation degree of steel slag. Concretes cast with the steel slag aggregates modified by EDTA gained higher compressive strengths and more stable volumes than that of concretes cast with the steel slag aggregates without EDTA.