INVESTIGATION OF STRUCTURE FORMATION PROCESSES IN LIME-BASED RESTORATION COMPOSITES

Abstract

The operational properties of composite materials are largely determined by the processes that occur at the beginning of their structure formation. Volumetric changes and plastic strength are considered as informative indicators reflecting the processes of structure formation and adaptation of lime restoration composites (plaster compositions) in the early stages of hardening. It is shown that these characteristics are sensitive to changes in the internal structure of the material, in particular to the coagulation of dispersed particles, the development of interphase contacts, and the formation of a spatially connected composite structure. The results demonstrate that volumetric changes and plastic strength reflect different but interrelated aspects of a single process–the formation of the internal structure of the composite and therefore can be considered as complementary indicators of structural evolution. The correlation between these indicators determines the ability of the restoration mortar to adapt to the deformation and moisture exchange characteristics of the porous limestone base without accumulating critical internal stresses. Based on experimental data, regression models and graphical dependencies were constructed, which clearly reflect the influence of composition on the nature of volumetric deformations and the kinetics of plastic strength growth. The obtained isosurfaces and time curves allow interpreting the change in properties through the dominance of certain mechanisms of structure formation at different stages of hardening. It has been shown that varying the composition of the composite allows for targeted control of the balance between deformability and the rate of increase in structural cohesion, which is a key factor in the formation of a compatible and stable contact zone. The results obtained confirm the possibility of using volumetric changes and plastic strength as a methodological basis for predicting the behavior of restoration mortars and adaptation processes in the "restoration mortar – base material" system and for designing plaster compositions focused on long-term compatibility and preservation of historic shell limestone buildings.