# Strength Characteristics of Historical Mortars—Experimental Study Using the Double Punch Method

## TL;DR

This paper studies the strength of old mortars from heritage buildings in Cracow using a minor-destructive double-punch method to help with structural analysis and restoration.

## Contribution

The study provides practical recommendations for using the double-punch method on historical mortars.

## Key findings

- The double-punch method is effective for testing historical mortars with minimal damage.
- Sample thickness and capping materials significantly influence test results.
- Practical guidelines for applying the method to heritage structures are proposed.

## Abstract

Identification of the strength characteristics of mortars in brick or stone masonry is crucial in the structural analysis of heritage buildings and selecting materials for their repairs and reconstruction. Non-destructive, minimally destructive, and minor-destructive tests have been developed to establish the strength of mortar in existing masonry. This paper presents strength tests on mortar samples extracted from bed joints of heritage buildings erected in the historic center of Cracow during the 19th and 20th centuries. The mortar samples were tested using the double-punch method, a minor-destructive technique especially useful for heritage structures where cutting out large masonry specimens is not possible due to conservation reasons. The impact of sample thickness and type of capping materials on the test results were analyzed in detail. Practical recommendations are also proposed for the procedure of the double-punch method in relation to historical mortars.