Influences of EDTA and Its Sodium Salt on the Carbonation Properties of Steel Slag Blocks
The preparation of building materials using accelerated carbonisation of steel slag is an efficient means of resourcefully utilising steel slag and adsorbing carbon dioxide(CO2).However,due to CO2 transport and kinetic limitations,carbonisation of steel slag is usually carried out at high temperatures,high pressures and pure CO2 concentrations.In order to reduce the energy consumption during the accelerated carbonisation process,steel slag blocks were tested for accelerated carbonisation at atmospheric pressure and low CO2 concentration.Ethylenediaminetetraacetic acid(EDTA)and its sodium salts,disodium ethylenediaminetetraacetic acid(EDTA-2Na)and tetrasodium ethylenediaminetetraacetic acid(EDTA-4Na),were doped into the steel slag blocks to assess the carbonation performance of the steel slag blocks by compressive strength and carbon sequestration rate,and to analyse the products and microscopic morphology using X-ray diffraction(XRD)and scanning electron microscopy(SEM)images.The results showed that the incorporation of EDTA and its sodium salt into steel slag blocks could enhance the carbonation strength and carbon sequestration rate,where the gain effect was EDTA-2Na＞EDTA-4Na＞EDTA.The incorporation of EDTA and its sodium salt did not change the product type of the carbonated steel slag,but formed more calcite with smaller particle sizes to fill up the pores,resulting in a more dense matrix.The conclusions of the study can providea reference for the resource utilisation of steel slag.
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