For testing how much CO2 the material is absorbing, we started small with our tests before progressing to the complete buildings. We detail all of this here https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4148065

But first we started with samples of concrete as above. We glued tubes into a hole drilled through the center of the sample.

Then we mounted samples to test stands and connected the aquarium air pump to continuously bubble air through each sample.  For each test we added vary amounts of Cation material such as CACL2 to the mix. And submerged the samples for varying amounts of time.