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KEY WORDS : Experimental Method, Evaluation of Restoration Materials, Lime Mortars, Lime Plasters, Experimental 
Techniques of Materials, Reproduction of Mortars, Design of Repair Mortars 
ABSTRACT: 
Our country is quite rich with historical buildings. Depending on various factors like time, increasing air pollution due to 
technological improvements of present era together with insufficiency of inspection lead to the formation of damages on these 
buildings which are part of our historical heritage. Conservation of such buildings which are as important as historical documents 
should be the first and foremost target of any project. Where maintenance is insufficient, conservation and restoration attempts 
should replace it. What is necessary in restoration is the use of material which resembles the original material to the closest degree or, 
producing appropriate material which is compatible with the properties of the original material. The first dimension of the current 
problem is the insufficiency of resources while the second dimension stems from the lack of proper evaluation of the material to be 
used in conservation and restoration. This study defines the importance of mortars and plasters along with their history and the 
reasons of deterioration. In addition, it sets up the information flow of mortar and plaster within a systematic decision making 
process. The necessary experimental methods for the production of new repair mortar or plaster that can be used in determining the 
character analysis of original mortar and deterioration morphology are also analyzed. Thus, a method that can be used in the 
conservation and restoration studies is determined with this paper. 
1. INTRODUCTION 
The number of different materials used in the historical 
buildings is limited. Generally, available regional materials had 
to be used due to necessity during the construction. What we 
name as traditional materials are consisted of stone, brick, 
wood, mortar and plaster. Among these, plasters and mortars are 
greatly affected by environmental factors and hence they are the 
ones that necessitate conservation and repair the most. 
Besides their functional necessity during the construction of the 
building, mortars and plasters carry an aesthetic value 
depending on their architectural form and construction 
techniques. Even though mortars and plasters serve different 
purposes within a building, their deterioration morphology and 
conservation attempts should be analyzed together since they 
are basically made out of similar materials. Mortar is a 
structural material that brings stone or brick together, which 
provide the stability of the wall. On the other hand plaster 
covers the façade of the building and preserves the material that 
constitute the structure of the wall from external weather 
conditions. Thus, plaster is not a structural material, it only 
serves to protect the building’s facade. While investigating the 
deterioration of mortar and plaster, which serve different 
functions, it is necessary to investigate if there is a decrease in 
their common and functional features, (if there is any). For 
example, as different from plasters, compression resistance and 
elasticity modulus of mortar, which bind the stone or brick 
together, is quite important. On the other hand, optimum water 
vapour permeability values, durability against acids or gas in the 
air, thermal dilatation and swelling by water are common 
S. Acun , ITU, Architecture Faculty, 80191 Istanbul -Turkey. 
important factors for both mortar and plaster. Among the 
historical mortars that have come to survive up until today, 
gypsum, lime and lime pozzolana have been used as 
binding materials. As aggregate material, river sand, pebbles, 
brick pieces and powder have been used together with hay,' 
horse hair, goat hair which have served as fibers. In our country 
we encounter Horasan mortar with varying mixture ratios in 
buildings from Byzantion, Seldjuki and Ottoman periods. This 
type of mortar is as strong as concrete and is made by binding 
lime together with varying proportions of river sand and brick 
pieces/powder that are used as aggregates. Horasan mortar has 
been widely used in Ottoman buildings especially in those that 
belong to the 15 th century and in the period that follows. In 18 th 
and 19 th centuries, lime mortar, named as “royal mortar” which 
was made of Italian pozzolana “poqdana”, has been used. Lime 
mortar is actually composed of non-hydraulic lime, which is 
irresistant to water, combined with pozzolana. In this way 
hydraulic lime is formed which is hard and resistant to water at 
the same time. Hence, it is also known as Horasan concrete in 
history. Lime mortar made out of pozzolana and brick pieces 
have been named by the Romans as “opus cementicium” and 
they have continued to survive until today. In addition these 
mortars have served to improve the cement technology of today. 
Towards the 20 th century, the hydraulic quality of cement and 
its feasible use has been combined with positive features like 
low stress, high deformation capacity and porosity of lime 
mortar and as a consequence, lime-cement mortar production 
has begun.The first step in the evaluation of mortar and plaster 
used in historical buildings is the accurate determination of the 
original material used and the reasons that have led to 
deterioration. The table in the following briefly summarizes the 
deterioration causes of mortar and plaster.