Meta has open-sourced BOxCrete, an AI model using Bayesian optimization to rapidly design concrete mixes with domestic materials, bypassing months of traditional lab testing. Deployed at Meta's Rosemount, MN data center, the system achieved 43% faster time to full structural strength, 10% reduction in cracking risk, and 100% domestic material usage. Meta is releasing the model along with foundational data from over 500 strength measurements across 123 different mix designs. This democratizes AI-powered concrete optimization for an industry slow to adopt technology, potentially reducing global CO2 emissions while improving construction speed and supply chain resilience.