MIT study shows CO2 injection makes cement 13 percent stronger, reveals hidden chemistry

MIT researchers used Raman confocal microscopy to observe how carbon dioxide reacts with cement during the first 24 hours of hardening. They found that CO2 triggers a temporary silica gel network that later converts into calcium silicate hydrate, the main binding compound. This process distributes strength uniformly through the material rather than clustering around cement particles. In lab tests, cement with CO2 equal to one percent of its weight showed 13 percent higher compressive strength after 24 hours compared to standard cement. The study clarifies that calcium carbonate particles are not the main driver of strength gain, contrary to earlier assumptions. The discovery allows engineers to optimize CO2 dosing for stronger, lower-carbon concrete. Since cement production accounts for roughly 8 percent of global CO2 emissions, this method could reduce the carbon footprint of infrastructure while improving material performance.