Abstract

     A study is presented on the use of a non-standard 40 × ۴۰ × ۴۰ mm3 specimen for the experimental measurement of the compressive strength of solid fired clay bricks extracted from existing masonry buildings. The viability of such specimen has been assessed by comparison with experimental results obtained with the standard 100 × ۱۰۰ × ۴۰ mm3 specimen. The use of the non-standard 40 × ۴۰ × ۴۰ mm3 has two main advantages. First, it significantly reduces the volume of sampled material, which can be severely restrained in architectural heritage buildings. Second, it allows carrying out tests in the three brick dimensions (length, width and thickness), and therefore investigating the anisotropy that clay bricks can exhibit depending of their manufacturing process. The experimental campaign has focused on three different types of solid fired clay bricks, namely mechanically extruded, hydraulic press moulded, and handmade units, with a total amount of 461 specimens. Using the mentioned small cubic specimen, a detailed research on the compressive strength and the anisotropy of different solid clay brick types has been carried out by applying a statistical approach. The experimental results and the statistical processing have shown that the proposed specimen can be utilized for a reliable estimation of the compressive strengths along the three main directions of solid fired clay bricks.

Introduction

     A large part of the built stock of many regions in the world consists of modern and historical masonry structures still in use and in need of maintenance and conservation interventions. Many of such structures are considered as architectural heritage due to their cultural value and to their contribution to the identity of historical towns and urban centers. The structural verification of masonry buildings, aimed to their maintenance or refurbishment, requires a detailed analysis of the performance against both gravity loads and horizontal actions. The analysis of existing masonry buildings, however, faces significant difficulties due to the complexity of masonry as both construction technology and structural material. One of the main difficulties lies in the realistic characterization of the mechanical properties and, more specifically, of the masonry compressive strength, which has often a critical influence on the structural performance of masonry members. The masonry compressive strength depends largely on the compressive strength of components (units and mortar) [1]. In specific, knowledge on the compressive strength of bricks (along with that or mortar) may enable an estimation of that of masonry using available empirical or analytical equations [[2], [3]].

Conclusions

     A study has been presented on the viability of determining the compressive strength of solid clay bricks by testing non-standard small cubic specimens of dimensions 40 × ۴۰ × ۴۰ mm3 (labelled as ‘C40’). The use of this small specimen allows the measurement of the compressive strength along the three brick dimensions (length, width and thickness). Therefore, the ‘C40’ specimen has enabled the investigation of the anisotropic response that is observed in some brick types depending on their manufacturing process. Moreover, the use of this small specimen allows reducing the volume of material sampled from existing structures, which may be severely restricted in the case of architectural heritage. The viability in the use of the ‘C40’ sample has been investigated by comparing experimental results with those obtained with a standard 100 × ۱۰۰ × ۴۰ mm3 specimen (labelled as ‘۱۰۰’).