I meant overestimate how much carbon it removes and underestimate how much it costs to remove carbon from the air.

And its not a new technology that can be improved with iteration - CO2 always takes energy to remove and its other ingredients always take energy to create.

Until we get essentially carbon free and cheap energy there's no excuse to waste it on low carbon concrete when we can use those resources more efficiently elsewhere.

If you're going to waste energy on physically removin CO2 from the air then you're best bet is giving China and India free solar panels rather than using solar panels to remove CO2 to put in concrete