Educational Linkage Approach In Cultural Heritage

Prof. JoAnn Cassar and Roberta De Angelis – University of MaltaProf. JoAnn Cassar and Roberta De Angelis – University of Malta

Educational Educational ToolkitToolkit

The Conservation Process

ModulModulee

44Basic Basic CourCourssee

Exercises Exercises

TopicTopic 4.C4.C Choose the mortar mix

Educational Linkage Approach In Cultural Heritage

Copyright ©ELAICH Beneficiaries 2009-2012This material is an integral part of the “ELAICH – educational toolkit” and developed as part of the project ELAICH – Educational Linkage Approach in Cultural Heritage within the framework of EuroMed Cultural Heritage 4 Programme under grant agreement ENPI 150583. All rights reserved to the ELAICH Beneficiaries. This material, in its entirety only, may be used in "fair use" only as part of the ELAICH – educational toolkit for the educational purposes by non-profit educational establishments or in self-education, by any means at all times and on any downloads, copies and or, adaptations, clearly indicating “©ELAICH Beneficiaries 2009-2011” and making reference to these terms.  Use of the material amounting to a distortion or mutilation of the material or is otherwise prejudicial to the honor or reputation of ELAICH Beneficiaries 2009-2011 is forbidden.  Use of parts of the material is strictly forbidden. No part of this material may be: (1) used other than intended (2) copied, reproduced or distributed in any physical or electronic form (3) reproduced in any publication of any kind (4) used as part of any other teaching material in any framework; unless prior written permission of the ELAICH Beneficiaries has been obtained.

DisclaimerThis document has been produced with the financial assistance of the European Union. The contents of this document are the sole responsibility of the ELAICH Consortium and can under no circumstances be regarded as reflecting the position of the European Union.

Prof. JoAnn Cassar and Roberta De Angelis – University of MaltaProf. JoAnn Cassar and Roberta De Angelis – University of Malta

Educational Linkage Approach In Cultural Heritage

4.3 Choose the mortar mixExercise 4-C

This detail shows the external wall of a building in Malta. As you can see, the wall has lost the mortar between the stone blocks, and it needs to be repaired to prevent water from seeping through. The wall is starting to deteriorate; the stone is soft.

Educational Linkage Approach In Cultural Heritage

4.3 How should it be done? Exercise 4-C

Like most of the buildings in Malta, the wall is made of a soft type of limestone called Globigerina Limestone.

Globigerina Limestone is a sedimentary rock formed from a loose sediment of tiny shells called “globigerinae” consolidated (compacted and hardened) into a solid rock.

It is very easy to quarry and carve.

Sample of freshly-quarried Globigerina Limestone

Porosity: high Hardness: medium Water absorption:high

Some of its properties

Educational Linkage Approach In Cultural Heritage

4.3 How should it be done? Exercise 4-C

Look at the different mortar samples below and read their properties. Try to find the best mortar sample for re-pointing the limestone wall based on these properties. To check the answer drag the chosen sample and overlap it on the freshly-quarried stone sample. Remember (from the previous presentation) what properties are considered “good” properties when compared to the stone properties.

MORTAR SAMPLE 4MORTAR SAMPLE 3MORTAR SAMPLE 2MORTAR SAMPLE 1

Porosity: high Hardness: soft Water absorption: high

Porosity: high Hardness: soft Water absorption: high

Porosity: high Hardness: mediumWater absorption: high

Porosity: high Hardness: mediumWater absorption: high

Porosity: very high Hardness: very softWater absorption: very high

Porosity: very high Hardness: very softWater absorption: very high

Porosity: lowHardness: hardWater absorption: low

Porosity: lowHardness: hardWater absorption: low

Freshly-quarried Globigerina Limestone

Porosity: high

Hardness: medium

Water absorption: high Porosity: high

Hardness: medium

Water absorption: high

Educational Linkage Approach In Cultural Heritage

4.3 How should it be done? Exercise 4-C

[To the web organizer: these comments should appear as pop-ups when each mortar sample is overlapped on the stone sample by the students]

MIX 4MIX 3MIX 2MIX 1

Well done! This is a good match!The colour is not very good but it can be modified easily by a conservator.

Yes, this is an acceptable match! This mortar has the same properties of the freshly-quarried stone, but it may be too strong for a deteriorated wall. Its colour can be modified.

Yes, this is a fairly good match.The colour is not very good but it can be modified . It is a weak mix and will work well with the deteriorated wall. It may need to be replaced often., especially if used on external walls.

Wrong match!This mortar is too strong for use with the weak masonry wall. Its colour is also difficult to modify (too dark).