This wall has “concrete cancer,” a destructive chemical reaction that cracks and crumbles concrete years after it’s poured. It’s part of a series of NIST experiments to understand how the overall strength of a building is weakened by concrete cancer – officially called alkali-silica reaction (ASR). The reaction happens in moist environments when the original concrete is made with rocks and/or sand that have a tendency to react and cement. The interaction creates a white, yellowish, or colorless