There is still a lot of awareness and industry knowledge to be developed here in Brazil about low carbon concrete. LEED is doing a good job about that and the majority of certified projects now consider some form of reduced impact via clinquer replacement. Brazil is not manufacturing as much steel anymore and we are mainly processing steel imported from China so blast furnace slag availability is limited. We are running short of rainfalls and dams are at a lower volume so coal fired power plants use is increasing, therefore fly ash is more available in the south region of the country.
I am not across the situation in Mexico.
Let me know if you need any further information.