Case study of the integrated strengthening of the underground Church of the Holy Assumption Nativity in Kiev-Pechersk Lavra is proposed as a description of the widespread composite materials use in reconstruction. This provides an opportunity for the development of a new direction in strengthening building structures and a significant reduction in the complexity, cost and time frames of work.

The object of amplification became the second oldest church in the Far Caves, which occurred between 1058 and 1062. 

Structurally, the volume of the Christ Nativity Church consists of arched different-span vaults, supported by massive earth walls and a brick column. Within the walls of the church there are five arched passages with a width of 550 … 1380 mm and a height of up to 2 m. The entire structural part of the church is in a sandy loam layer. Depth from the surface of the earth is about 6 m.

When examining the condition of the object the following defects and damages were revealed :

– deep cracks in the area of the arched passage in the altar of the church;

– offset at the junction of the brick supporting column with the arched vault;

– individual cracks in the arched passages and arches of the church;

– loss of general stability of the iconostasis elements;

– inclined cracks up to 2 cm in the vertical elements (walls) of the church.

With the problems encountered, it was decided to fight with the help of composite materials. Basalt rebar is a corrosion-resistant material that has a life-period for at least 80 years. Also non-metallic materials have sufficient mechanical properties for use as reinforcing elements; non-metallic basalt rebar has elastic properties and, when bent, takes the form of a reinforcement surface, and if the surface has a curved shape, the effect of prestressing occurs, which makes it possible to more effectively incorporate reinforcement into the structure at the stage of reinforcement. Composite materials are also convenient for use in cases, when it is necessary to maintain the form of structures that are strengthened (historical and architectural monuments). Since the use of composite materials is an effective form of the reconstruction (restoration) of historical and architectural monuments, which provides a significant reduction in the complexity, cost, time of work with a significant increase in the time intervals between repairs, this material was used in the process of reconstruction.

It is also worth emphasizing that the implementation of the project itself was preceded by a series of experimental studies with the creation of model samples.