Abstract: A method of controlling the physical properties of cement by adding a predetermined amount of a second phase to a first phase cementitious precursor. The second phase is added in the form of seed crystals having controlled sizes, shapes, and compositions. The seed crystals provide growth sites upon curing the cement for a second phase in the cement body. The curing is accelerated by the presence of the seed crystals. Control of the microstructure of the resulting cement body through controlled distribution and growth of the seed crystals enables the formation of a cement body having precisely controlled physical properties.