The multi-scale approach of masonry, paradigm of clay brick

Abstract

Recent progress in nanoscience and engineering allows advanced characterization of materials. This type of characterization includes investigations revealing the scale dependent microstructure and mechanical as well physical properties of each component incorporated in the heterogeneous material. Its applicability and efficiency is confirmed in the field of cement based materials where the paradigm of these materials is solved, and universal buildings blocks and the multi-scale nature are well described. As a consequence, material researchers and engineers have knowledge about the impact of basic constituents and microstructure on macro behaviour of cement based materials. In the masonry field, a quite diverse situation is found. Although clay brick is among the oldest building materials, the main building blocks are still unknown. This knowledge gap is apparent in structural masonry, since the present homogenization and upscaling techniques consider only mortar joints, brick units and interface as a basic units. Here, the mechanical properties and elementary arrangement of these three components in the representative volume element (RVE) are assumed to govern the behaviour of masonry as a composite. But, it is understood that mortar may be broken down to lower scales, and its macro mechanical properties considered in the already developed approaches are governed by the lover scale components and its microstructure. Similarly, as it is shown by the authors in this contribution the brick unit may be broken down to lower scales, in which the basic material components and theirs properties are inherent. Therefore, the macro behaviour of composite masonry wall and its durability is considered to be ruled by the phenomena from the much lower scales present in the mortar, clay brick and the interface of these two.