Supersulfated cement (SSC) utilizes up to 70%—85% slag and around10%-15% calcium sulfate while using a minimal amount of Portland cement as an alkaline activator. The hydration of slag is very slow at early ages and thus results in a slow rate of early strength development of SSC. The amount of reacted slag can be estimated with an ethylene-diamine tetra-acetic acid (EDTA) dissolution technique. However, this technique was found to be problematic, and it underestimates the quantity of slag reacted. To directly determine the amount of unliydrated slag in SSC， polished and carbon-coated paste samples at1,3, and 7 days are examined using back-scattered electron imaging (BSE). Greyscale thresholding is used to identify the amount of anhydrous slag. The volume fraction of unhydrated slag is determined from the BSE images and then divided by the known volume fraction of slag in the SSC mixture to identify the percentage of slag reacted as a function of time. The results are for the quantification of slag dissolution in SSC.
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