Deterioration of ancient masonry is a contemporary problem. The initial properties of the masonry material that determine its durability, deterioration and degree of preservation have led to the appearance of different approaches towards choosing the technology for restoring masonry. The success of any restoration is largely determined by its compatibility with the original materials used, which requires, as a rule, a complex and long process of selecting their composition. One of the main technological approaches in the science of restoration materials is to search for the optimal composition of the material within a given time limit. This paper presents an approach which uses a large number of variables within strict boundary conditions. The solution to this problem can be found in the field of mathematical modelling using experiment planning methods. The paper presents a method developed for mortar optimization which makes it possible to obtain the desired result within a relatively short period of time.

The article presents the results of a study of the effect of microfiber based on high - density polyethylene and polybenzoxazole on the axial stretching of fibrocomposites. The definition of the phenomenon of deformation hardening of a hydration hardening fibrocomposite is proposed. Characteristic deformation diagrams of various fiber - reinforced composites are obtained and analyzed. The ranges of values of deformation hardening and plastic deformation are determined, as well as the factors that determine these characteristics are stated. From a practical point of view the increase of the resistance of fibrocomposite while maintaining its integrity in conditions of high values of plastic deformations opens up the possibility of using such materials for repairing damaged superstructures and ceilings, durable (heat and bio - resistant) sealing of joints of precast reinforced concrete structures.

Lime dry mixes for plaster and masonry are widely used for the restoration of architectural monuments. At the same time, lime mortars in modern conditions can be considered as insufficiently technological, since their hardening largely depends on the relative humidity of the ambient air and requires a rather long period of exposure to achieve normalized strength. This leads to a slowdown in the pace of work and a general increase in the cost of restoration. To overcome this shortcoming while maintaining other performance characteristics of the lime mortar unchanged, it is proposed to modify the composition of the mix by introducing an additive that accelerates setting and hardening in the optimal quality. In this paper, additives of various nature are considered. The most effective additives from the point of view of setting and hardening acceleration, but not radically changing the basic operational properties of the solidified mortar, have been determined. Compressive strength and vapor permeability were considered as the main properties of solutions.

The paper defines the principles for structure-simulation modelling of conglomerate material properties by an example of cement compositions. The constitutive essence of the principles consists in generation of hierarchical models of individual structural levels (including a sub-microstructural level) based on material structure data. Parameters of properties, determined for models of the previous structural level, are used as input data of continuum environment, which forms a matrix element for models of the following level.Detailed development of a general model for a composition makes it possible to correlate structural features at the level of a nanometer with material macro properties. Algorithms simulating physical and mechanical processes and phenomena, typical of cement systems individual properties (dry shrinkage, straining under load), are implemented based on the finite element method by determination of corresponding external and internal loads.Application of the finite element method makes it possible to completely maintain geometrical and physical "reality" of the model describing specific features of the structure under study; and enables solutioning, with a high degree of confidence, of theoretical and practical issues related to determination of quantitative effect of structure discrete parameters on various material properties.

The reliability of historical buildings` brick structures is usually evaluated on the basis of analysis based on empirical formulas that use characteristics of brick and masonry mortar, which are obtained as a result of testing samples of materials taken from the structures. The practice of making such evaluations often shows an obvious discrepancy between the visual state of the structure and the analysis results obtained. Brick-masonry that does not have signs of the load-bearing capacity loss may be evaluated as emergency brick-masonry, and structures that have clearly lost their integrity are sometimes assumed to be sufficiently reliable. The currently valid regulatory documents provide for the possibility of using standard samples for direct evaluation of the strength of brickwork, but it requires adaptation to the conditions of the of historical objects` survey. This paper presents substantiation for the need of using standard samples to evaluate the strength parameters of historical objects` masonry.