No abstract

With time a problem of preserving architectural heritage sites becomes more acute, since many unique listed buildings are in an emergency state and require the restoration measures that take into account the specifics of the historical environment, an analysis of the technical condition, evaluation of the monuments’ value, the possibility of their functional adaptation to modern needs. The search for solution to preserve such objects is often complicated by the development of a modern urban renovation area around them and by the difficulties of maintaining a complete historical appearance of cities when adapting listed buildings to the functions demanded in modern society. The article proposes an approach to choose the best version of the project proposal for the restoration of a cultural heritage property of regional significance. The building is designed in an eclectic style in the city of Tambov. 11 versions of the author’s project proposals for the restoration transformations are considered, which preserve the historical appearance of the building and various transformations of the internal volume and development options of the adjacent territory. 14 criteria are proposed to evaluate the qualities of versions. To select the best restoration version a scientific method of a multicriteria comparative analysis was used, which made it easy to compact a large amount of information about the object to a single quality parameter in the form of a synthetic indicator for each version. Simultaneously the weight factors of the criteria were established on the basis of expert evaluation obtained from the professional groups of various profiles: architects, representatives of the contractor, state supervisory authorities, the owner of the object, the tenant of the object.

An unconventional approach to the design of cement mixtures with the addition of cement bonded particle board (CBPB) production waste is presented, which is characterized by high water consumption. For various compositions of fine-grained concrete prepared in accordance with the simplex-lattice design of the experiment, compressive strength and bending, as well as density of the samples, depending on the mixture factors, were researched. The fractions of CBPB wastes, water and sand at constant cement consumption were chosen as the influencing factors. For practical purposes, related to the design of cement composite compositions with the addition of CBPB wastes and with the determination of optimal values of the selected factors, mathematical models have been constructed on the basis of laboratory experiment data and with their help, the optimal ratios of components in the mixture have been determined. It was found that the content of water for the mixture mixing in the mixture has a significant effect on the strength characteristics of composites: increase of the strength of materials with a decrease in the water-cement ratio is a characteristic for compositions with the minimum amount of CBPB waste; increasing the content of the CBPB waste in the mixture the increase of the water-cement ratio leads to gain in strength. Optimal ratios of the mixture components providing maximum utilization of CBPB waste without loss of strength of composites are given.

The object of study is a cement composite material with powdered utilized optical discs. The objective is to establish the dependences of the main strength characteristics – com-pressive strength, bending strength, and density – on the amount of waste added into the mix-ture and the water-cement ratio.The compositions of the mixtures for the production of the cement composite material samples consisted of the following components: cement, sand, powdered waste in the form of utilized optical discs and water.Based on the results of testing the samples, mathematical models have been developed which describe the dependences of the physical and mechanical properties of the cement com-posite material samples on the fraction of waste and water-cement ratio. It was found that with an increase in the amount of powdered waste added into the mixture, it reduces the compressive strength, bending strength, and density of the samples under study, however, the optimization of the water-cement ratio makes it possible to obtain equal strength compositions with a differ-ent fraction of waste.Component compositions of cement composite material mixtures with the addition of powdered utilized optical discs in the amount of 10 to 25 % of the total filler mass, which can provide construction products with a compressive strength class B20, are presented.