Figure 1: The left and center diagrams show the structure of cement hydrate as determined by the researchers’ model, which calculates the positions of particles based on particle-to-particle forces. Each simulation box is about 600 nanometers wide. The packing fraction (the fraction of the box occupied by particles) is assumed to be 0.35 in the left diagram and 0.52 in the center one. Open pores, indicated by the white areas, are more prevalent at the lower packing fraction. The right-hand diagram is a sketch of cement hydrate published by T.C. Powers in 1958.