Effect of Thin Cement-Based Renders on the Structural Response of Masonry Wall Panels

Marco Corradi,Romina Sisti,Antonio Borri

doi:10.3390/app8010098

Abstract

URM (Unreinforced Masonry) historic buildings can be generally arranged into three categories: adobe, brick and stone masonry. However, a common feature of URM structures is typically the low mechanical properties of the masonry material, especially in terms of shear strength. URM buildings are not amenable to seismic analysis, and the relatively low strength of stone and brickwork masonry often requires expensive and invasive retrofitting intervention. Hard, intractable stones broke artificially or naturally into random shapes were often used for construction in many parts of Europe and constitute the main material of historic buildings. Thin, cement or lime-based renders are often employed to protect masonry construction, but these are frequently ignored in analysis and design. This paper shows how standard, thin, cement-based renderings can highly enhance the lateral load-capacity and shear stiffness of wall panels. An experimental campaign was carried out on-site to assess the effect of cement-based renders. In detail, compression and shear tests were conducted on twelve full-scale wall panels up to failure, and comparisons are presented to study the effect of cement-based renders on the structural behavior of stone and brickwork masonry panels.

Highlights

From medieval times to the modern era, the use of stone for private, public and religious buildings and infrastructures was very common in many parts of Europe
The use of rubble or barely cut stone, the absence of adequate connections between wall leaves, and attempted to measure the mechanical properties of historic masonry, by considering different the lack of skilled masons and adequate resources were the main causes for the low quality of constituent materials, arrangements, dimensions and shapes of the blocks
Knowledge of the mechanical characteristics of Unreinforced masonry (URM) masonry is of critical importance for any cement-based renders

Summary

Introduction

From medieval times to the modern era, the use of stone for private, public and religious buildings and infrastructures was very common in many parts of Europe. Brickwork masonry is relatively more recent in Europe: solid hand-made bricks were used with increasing diffusion and frequency from the 1600s. These artificial blocks were used for public buildings or infrastructures, but they became extremely common in the 19th century in many parts of Europe in the housing construction industry [6,7]. Today, most of these buildings belong to the cultural heritage and their conservation is often a priority for local governments and conservation bodies. Historic masonry buildings have been designed in the past with little or no regard for the effects of the seismic action

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