Micro-chemical/structural characterisation of thin layer masonry: A correlation with engineering performance

Abstract

Masonry is one of the most ancient methods of construction. The types of blocks and mortars used over the centuries have developed considerably with the introduction of various types of materials. A multidisciplinary investigative approach, involving both engineering and material sciences expertise, will be necessary for a complete evaluation of the behaviour of masonry elements. From the engineering point of view, the transverse lateral load capacity of masonry built using solid dense concrete blocks with thin layer mortar, is up to four times that of similar blockwork constructed using conventional mortar. Both the mortar and block constituent material’s properties alter the joint strength with enhancements to tensile flexural bond strength. When thin layer masonry technology (TLMT) is employed, in conjunction with solid dense concrete blocks, the masonry behaves more as a concrete plate than conventional blockwork. The engineering properties of masonry elements are not only related to the engineering properties of the blocks and mortars used, but also to how the bond at their interface interacts. Testing on two different block types, and one mortar was undertaken to verify this hypothesis. Engineering testing was carried out to determine the flexural strength of the material. This approach was combined with petrographical examination of the two different types of block and the bond zone using micro-analytical techniques, (OTLM, SEM and EMPA). Observations using SEM and EMPA techniques revealed that these differences depend on the composition of both blocks and mortar, and in particular they are related to the petrographical composition of the parent material of the block. These aspects affect how the bond layer forms and influence the mechanical properties of the joint.