Evaluation of Performance of Matured Hydraulic Grouts: Strength Development, Microstructural Characteristics and Durability Issues

The present paper evaluates the performance of matured hydraulic grouts, with respect to their composition and the induced microstructural characteristics. Four different grout compositions were examined; three grouts based on natural hydraulic lime (NHL5), plain and in combination with pozzolan, and a ternary white cement - pozzolan - hydrated lime mixture. Both grout-only specimens and composite injected material have been examined and injected grout - masonry material interaction issues are discussed

Shake-Table Testing of a Cross Vault

Domes, vaults and arches are structural components of high vulnerability, due to the horizontal component of the thrust they impose to the supporting vertical elements (piers or walls), accentuated by the asymmetry of loading due to seismic actions. In order to explore the possibilities of reducing this vulnerability, a cross vault made of brickwork and supported by two stone masonry walls was tested on the earthquake simulator. A series of seismic tests was performed to the specimen at its as-built state, as well as after strengthening using techniques adequate for monuments, namely, grouting of piers, arrangement of struts/ties at the base of the cross vault and vertical prestressing of the masonry piers. The tests have confirmed the vulnerability of the original specimen, as well as the improvement of its behavior after strengthening, in terms of sustained maximum base acceleration, deformations and observed damage

Shake-Table Testing of a Cross Vault

Domes, vaults and arches are structural components of high vulnerability, due to the horizontal component of the thrust they impose to the supporting vertical elements (piers or walls), accentuated by the asymmetry of loading due to seismic actions. In order to explore the possibilities of reducing this vulnerability, a cross vault made of brickwork and supported by two stone masonry walls was tested on the earthquake simulator. A series of seismic tests was performed to the specimen at its as-built state, as well as after strengthening using techniques adequate for monuments, namely, grouting of piers, arrangement of struts/ties at the base of the cross vault and vertical prestressing of the masonry piers. The tests have confirmed the vulnerability of the original specimen, as well as the improvement of its behavior after strengthening, in terms of sustained maximum base acceleration, deformations and observed damage

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