Heavy Metal Leaching, CO2 Uptake and Mechanical Characteristics of Carbonated Porous Concrete with Alkali-Activated Slag and Bottom Ash

Abstract

In the present study, a porous concrete with alkali activated slag (AAS) and coal bottom ash was developed and the effect of carbonation on the physical property, microstructural characteristic, and heavy metal leaching behavior of the porous concrete were investigated. Independent variables, such as the type of the alkali activator and binder, the amount of paste, and CO2 concentration, were considered. The experimental test results showed that the measured void ratio and compressive strength of the carbonated porous concrete exceeded minimum level stated in ACI 522 for general porous concrete. A new quantitative TG analysis for evaluating CO2 uptake in AAS was proposed, and the result showed that the CO2 uptake in AAS paste was approximately twice as high as that in OPC paste. The leached concentrations of heavy metals from carbonated porous concrete were below the relevant environmental criteria.