CO2-injected cement gains early strength via a transient silica gel network
MIT researchers used Raman spectroscopy to watch CO2-injected cement paste undergo a three-stage reaction: quick calcium carbonate formation slows hydration, a transient silica gel forms and disperses through the paste, and as the gel is consumed, a more evenly distributed calcium silicate hydrate binder forms, yielding about 13% higher compressive strength at 24 hours with 1% CO2 by weight. This mechanism helps explain the strength boost of CO2-injected cement and points to potential emissions offsets, though dosage must be carefully managed to avoid premature carbonate locking.