I didn't know that. According to
Emissions from the Cement Industry it is currently 50% of total emissions; I only addressed the other 50%. To which my answer is: "Just plant more trees!" If we terraform Earth with the equal numbers of trees to remove cement kiln chemical reaction CO2, then we should be OK, but I think there's a transport problem getting the CO2 to the trees. Maybe we can pipe it in to those new forests. Then, I'd look to removing the energy CO2 by using solar as I described.
The conveyer belts bringing in lime from the mines (all but 1 cement factory in the world get their lime from colocated mines (since it is (considered) uneconomical to do otherwise)) could run through tubes that carry the CO2 back the other way for a large part of the distance, reducing overall cost of transporting the CO2 to the man-made forests. Unfortunately, I don't think it could be mixed with the water misting systems to hydrate the terraformed forests, since that creates "Carbonic Acid". Nothing is free I suppose.
Some answers to that question:
Fast growing: CO2 (carbonic acid) uptake through roots? - GardenBanter.co.uk
http://www.treedictionary.com/DICT2003/shigo/RHIZO.html
The last link gets deep into chemistry. I haven't figured out if Carbonic Acid helps or not from that description, yet.