To study the process of structure formation of the cement composition, the method of infrared spectroscopy, X-ray phase analysis and electron microscopy were used. With the help of mechanical mixing it is difficult to provide the binder with the right amount of water. This task is performed by a complex additive, improving the wettability of cement particles. By reducing the content of calcium hydroxide, the possibility of the formation and existence of polybasic calcium hydroaluminates decreases. This circumstance prevents the formation of calcium hydrosulfonate (GSAC) in the later periods of hardening. On electron micrographs of cement stone samples with the addition of the obtained complex additive KDj-3, the pores are filled with both gypsum and calcium hydrosulfonic aluminum. The compaction and hardening of the structure of portland cement compositions in the initial stages of hardening is a consequence of the fact that both gypsum and calcium hydrosulfonic aluminate, with the addition of a complex additive, crystallize with an increase in volume
