Reactions between Ca(OH)2 and CO2, and Sr(OH)2 and CO2
Your solid is the respective carbonate. Group II bicarbonates can form aqueous solutions, but do not form stable solids, ergo the solid flakes must be carbonate and formed along the lines of:

$$\ce{Ca(OH)2 (aq)+ 2CO2 (aq/g) &lt;=&gt; Ca^2+ + 2(HCO3)- (aq) &lt;=&gt; CaCO3 (s) + CO2 (aq/g)}$$