1. Both of the main groups of problems of physicochemical mechanics are associated with problems of contemporary colloidal (chemistry: 1) formation of three-dimensional disperse structures for production of hard substances (constructional and building materials with specific mechanical properties; 2) dispersion of solids-development in them of new surfaces in processes of deformation and breakdown during working under pressure, cutting and crushing. 2. Coagulated structures possess relatively low strength, complete thixotropy and very pronounced plasticity. Under low stresses their substantially unstressed structure undergoes slow flow with maximum viscosity which may exceed the minimum viscosity of a structure under maximum stress in flow by a factor of the eighth power. All the characteristics of coagulated structures are explained on the basis of the presence of thin residual layers of liquid medium at the sites of linking of the particles. 3. Coagulative structure-forming processes can be controlled by addition of agents that modify the shape, dimensions and linking conditions of the particles constituting the structure. 4. Crystallized structures formed by direct intergrowth of crystallites of a new phase, possess maximum strength, and are entirely free from thixotropy and plasticity. Plastic and elastic properties are imparted to such structures by the presence of elements of structure (crystallites or macromolecules), but these properties are lacking in the system as a whole. Development of crystallized structures constitutes the basis of processes of setting of mineral binders. For the purpose of obtaining dense, strong and durable concretes, the processes of structure-formation must be controlled by small admixtures of surface-active plasticizers and by mechanical vibration. This procedure slows down structure formation in the initial stage of preparation and placing in position of concrete mixes, and after completion of this period the structure formation is able to proceed with maximum speed. 5. Subsequent processes of recrystallization of intergrown portions, which are always thermodynamically unstable, lead to lowering of strength of the crystallized structures and can be the main cause of breakdown of concretes and other structural materials in the water-saturated state. These processes slow downand can substan tially cease on transition to dense structures with a very small exposed porosity and with reduced solubility of the fresh hydrated forms. 6. Control of the processes of deformation and destruction of solids, metals for example, is possible by means of the adsorptive action not only of ordinary surface-active substances but also of melts or thin coatings of surface-active metals. These phenomena were studied by elongation of zinc monocrystals coated with thin films of tin or mercury, and are reflected in lowering of strength by a factor of ten and in embrittlement or (under small stresses) in a sharp rise in creep rate.Here the decisive factor is the temperature and the type of stress in association with the action of a surface-active agent or impurities. 7. The recorded observation enable control of processes of mechanical working of metals, structure formation, abrasion, and wear.