The influence of brick dust and crushed brick on the properties of lime-based mortars exposed at elevated temperatures

摘要

Brick residues, such as brick dust and crushed brick, have been diachronically used in historic mortars, both as binders and aggregates. Their application served as a mean to increase the pozzolanicity of the matrixes, enhancing resistance to humidity, decrease the density of the mixtures and add special hue to the structures. On the other hand, the performance of traditional mortars at elevated temperatures is a sig-nificant aspect that should be taken into account, in order to assess the preservation state and residual capacity of historic structures, as well as to design fire resistant restoration materials, under the prism of compatibility. In this study, three mortar series were manufactured, based on lime (L), lime : natural pozzolan (LP-1:1 by weight), lime : natural pozzolan : brick dust (LPB-1:0.8:0.2 by weight). In order to envisage the role of crushed brick in the matrix, they substituted the 40% of natural aggregates in the same gradation (0 & ndash;8 mm). The physico-mechanical properties of the mortars were tested at 28 and 90 days, while they were further exposed at elevated temperatures, concerning 200 degrees C, 400 degrees C, 600 degrees C, 800 degrees C and 1000 degrees C. Their post fire properties (physico-mechanical, microstructural) were recorded, so as to iden-tify the preferable testing age of lime-based mortars and the impact of brick residues on their behavior. From the evaluation of the results, it was asserted that the 90d age seems to be more representative, while crushed brick and brick dust enhanced structural integrity throughout extreme temperatures.(c) 2021 Elsevier Ltd. All rights reserved.