It is estimated that 4 billion tons of cement are manufactured each year. To speed up CO2 uptake, “instead of mixing calcium oxide with sand, they mixed calcium oxide with another mineral composed of magnesium and silicate ions. The heat catalysed an exchange of ions, forming magnesium oxide and calcium silicate: alkaline minerals that react quickly with acidic CO2 in the atmosphere.” Far quicker than most concrete, anyway…
Those bicarbonate ions are great for combating ocean acidification, they act as a pH buffer. Ocean acidification is rising due to increased atmospheric CO2 levels and that decrease in pH makes it harder for macro life forms to utilize carbonates to form shells and drives extinction. By increasing the concentration of bicarbonate, the carrying capacity of the ocean to absorb atmospheric CO2 without changing the pH is increased.
In this context tho, what you say reminds me of geoengineering and I consider it to be an extremely dangerous approach.
Not all geoengineering is the same. Beavers are geoengineers. We have already had a crazy huge impact on this planet, we should absolutely do something to mitigate these effects. A distributed (as opposed to all in one location) carbon cycle buffer is about the least harmful effect one can hope for and still have a positive impact.