Behaviour of masonry wallettes made from a new concrete formulation under combination of axial compression load and heat exposure: Experimental approach

This study was undertaken to evaluate the thermo-mechanical behaviour of masonry wallettes constructed using blocks made from lightweight concretes of experimental compositions under an axial compression load combined with heat exposure. A comprehensive experimental investigation was carried out on two different types of masonry wallettes at temperature levels ranging from 20 °C to 400 °C. The wallettes were produced using two types of lightweight concrete blocks, the first incorporating expanded clay and the second using by-product materials which consisted of recycled waste glass and metakaolin. The vertical deformation, load-bearing capacity and failure modes were determined experimentally. Furthermore, the modulus of elasticity was determined for both types of wallette and their constituent concrete blocks and cement mortar.The results obtained showed that the percentage decrease in the strength of both lightweight concretes when exposed to various temperatures compared to that at ambient temperature reached almost 30%. In contrast, the cement mortar exhibited an increase in strength of approximately 20%. A significant reduction in the value of modulus of elasticity was observed for the constituents of wallette, whilst the entire masonry wallettes showed a minimal reduction for both types. Clear improvements in thermal behaviour were observed for both types of masonry wallettes. The masonry wallettes formulated using expanded clay lightweight concrete blocks exhibited failure due to explosive spalling at 400 °C with no mechanical load, whereas the second type of masonry wallettes (the modified wallettes) did not show such behaviour.

► Minimal reduction in the compressive strength value of masonry wallettes was observed.
► Lower vertical displacements compared to those reported in BS EN were observed.
► The reference wallettes samples tested at 400 °C failed due to explosive spalling.
► Greater improvements in the duration of heat equilibrium were achieved.