From my understanding the most efficient way to achieve carbon...

From my understanding the most efficient way to achieve carbon emission reductions in cement/concrete industry is to replace the clinker which equate to 1 tonne of CO2 into the environment for every 1 tonne of clinke, with a supplementary cementious material (SCM).

In Europe and North America, the cement industry is already adjusting its blends/binders with some using between 20-50% metakaolin (HRM) and in doing so are reducing carbon emissions by these levels (see LC3), the challenge IMO is cost as clinker, I'm lead to believe is around $200-250/tonne, so to see faster adoption by cement industry in Australia, without more aggressive carbon reduction legislation from Govt, which some predict is coming - you need a HRM that not only delivers the carbon benefit, but has a level of cost parity to accelerate adoption.

Challenge is you need an extremely high-quality raw ore kaolin to be able to deliver a HRM (ie no water-washing etc) that has both the economic and climate drivers for the Aust cement industry to act.