THE SIGNIFICANCE OF DETAILED SURVEY FOR AN ADEQUATE GROUTING APPLICATION

Grouting constitutes one of the most common techniques applied for the repair and strengthening of masonry structures or fissured architectural members, when interconnected voids in adequate percentage are present. This technique can also be appropriate for the in situ consolidation of detached and cracked mosaics and wall paintings. Although grouting is a non-reversible technique, it is well accepted even in monuments of high historical and architectural value, since it has the advantage to retrieve the continuity, cohesion and strength of the damaged structures without altering their morphology, geometry and load-bearing system. To achieve this goal, the design of the grout composition should satisfy a series of performance requirements involving injectability, strength and durability aspects. Nevertheless, the careful design of the grout composition cannot by its own ensure the successful completion of the grouting intervention. Evidently, particular care has to be taken for the execution of the whole intervention in situ. One of the major parameters affecting the adequate application of the technique is the installation of the grout entrance and exit tubes so as to reach the internal voids, fissures and discontinuities present between masonry leafs or between leafs and infill material. In this paper, the importance of a detailed geometrical survey of all masonry faces and their pathology will be presented, together with the methodology to be followed in order to design the grid of grouting tubes to be installed. Furthermore, the type of tubes and the way of their installation will be described. This procedure consists of different phases, which need a detailed design and programming and constitute a prerequisite for achieving strength increase and improvement of the monolithic behaviour of the damaged masonry. The whole procedure will be highlighted using as an example the case of the piers of the drum of the Katholikon of Daphni Monastery