The microstructure of concrete consists of an intricate network of pores at length scales from nanometers to millimeters, of which only the larger ones are seen above. The pore network makes concrete a hygroscopic material, sucking in water from its surroundings, as shown in the time-lapse of CT scans done in IAM's lab. In one project at the Institute of Applied Mechanics, we study numerically and experimentally what happens when this water freezes and expands: under what conditions will the concrete crack under the pressure?