چكيده لاتين :
Next to the archaeological excavations, conservation and restoration of remains of monuments
in the fields have received the attention of scientific archaeological excavations. Exposure of
new finding materials to the microclimate conditions of earth surface causes to encourage their
degradation process. Humidity and cryogenic fluctuations are the most important destructive
factors for the architecture remains. Since a number of sites in the north and northwest of Iran
encounter precipitation humidity and consequently the destruction of architecture remains, it
appears that isolating outer remains of these structures using the compatible mortar is one of the
best methods to reduce their damage. Lime mortar is appropriate for this purpose owing to its
acceptable characteristics against the humidity. In this research, cow dung ash, rice husk ash and
wood (with specific gradation) were used to optimize the lime mortar. The mix of these
materials with lime paste prepared 6 different types of lime-pozzolan mortar. To determine the
appropriate sample in terms of durability and consolidation against the natural cycles,
accelerated aging tests including wetting and drying cycles, freezing & thawing and salt attack
cycles as well as physical characteristics (densitometry, water absorption, and durability) for all
types. The results of above processes indicated that the compositions of cow dung ash
pozzolan’s have better resistance to the aging cycles and other physical experiments. Using
XRD and XRF analyses, the structure and the amount of mineral phases were determined.
Based on the results, it is recommended that lime mortar (optimized with cow dung ash) be used
in the historic monuments and the humid climates of the north and northwest of Iran.
Conservation of the historical works while archeological excavations and the conservation,
restoration, and maintenance of the obtained remnants in the excavation area, including tombs,
architectural remnants, foundations, and even some of the ornaments after excavation are among
the moral and professional principles of the scientific archeology.(Sease,1996) The necessity of
the conservation of the archeological remnants in the recent century has been one of the most
significant parts included in the macro planning of the archaeological approaches and cultural
heritage-related knowledge. Among the measures taken for the conservation of the architectural
clay and adobe remains after archaeological excavations are: 1) temporary conservation of the
hills within the excavation times; 2) re-burial by re-filling the excavation area; 3) bricklaying
and covering the walls and the remnants works in the area; 4) implementing roofs and shelters
in the area for the temporary or permanent conservation; 5) using chemical and biological
substances to strengthen the walls; 6) the use of geotextiles (permeable polymer textiles), and 7)
coating the surface in the cold or humid regions.(Baghbanan et al, 2016; Rahmani,2006,
Stanley Price,1999; Jandro et al 1999) Also, the northwest of Iran is among the rich regions of
Iran in terms of archeology and tourism attractions, with an area of 7.2% out of the country's
total area.(Negahban,1998) The northwest part of Iran is among the mountainous regions with a
cold and dry climate in terms of climate conditions, causing the ancient sites to be severely
damaged after archeological excavations. Therefore, it is necessary to prioritize compatible
solutions in conservation measures. One of these measures is the use of protective mortars. The
construction technology and mix design of this kind of mortars must be recognized to achieve
the most efficient and stable formula; because it leads to the principled conservation in
maintaining the obtained remnants in the ancient sites and saving the conservation costs in the future, in addition to achieving a mixture and processing methods and making the optimal
mortar. (table 1)
How to use compatible mortars to protect architectural remains from archaeological excavations
in the northwestern climate of Iran.What variable depends on the quality of compatible limebased
mortar with natural fillers? The protection of ancient sites after exploration in the
northwestern climate can be done with compatible and eco-friendly calcareous mortar. The
quality of lime-based mortar compatible with natural fillers depends on the high silica content
of the filler.
Mortar Manufacturing: Lime was kept constant at 30%, and wood ash, rice husk, and animal
waste were used as a pozzolan to mix the mortar filler to optimize the lime-based mortar. Six
lime-based mortar mixtures with different amounts of rice husk ash (20, 35%), wood ash, and
animal waste (10 and 35%) were used. 16 cubes were prepared from each mortar sample.
Mortar samples were tested and analyzed to complete the setting reactions after 27 days from
manufacture time. (Table 2). aboratory Studies: Laboratory studies include the determining
examinations of the physical features of the samples (humidity percentage and water absorption,
density, and porosity), (table.3) geological structure by determining the elements using X-Ray
Fluorescence (XRF) analysis method, fuzzy determination using X-Ray Diffraction (XRD)
analysis, and assessment of endurance properties based on the national and international
standards(Table 7-8 ,Figures 10-11). The consecutive wetting and drying cycle, Freeze-Thaw
cycle, the endurance against salt hydration cycle, mortar samples durability test.(Figure 1-3- 6-8
and Table.4-6).
After archeological excavations, the key issue of historical sites is increasing the humidity
percentage and cold and heat fluctuations. As stated in the research literature, there are various
solutions to reduce and manage humidity and cold fluctuations. In this study, using a durable
and optimized mortar system ware studied to reduce the destructive effect of the above factors,
especially in the northwestern region of the country. Accordingly, native and natural pozzolans
were used to optimize the lime-based mortar. The applied pozzolans in this study include rice
husk ashes, cow dung ash, and wood ash. According to the conducted studies, six different
groups of mortar with different ratios were manufactured from the combination of three
pozzolans along with sand and lime paste. Then, after 27 days to complete the mortar reaction,
the proper samples were prepared for laboratory tests. These tests include accelerating aging
methods (drying and wetting cycles, freeze-thaw cycle, and salt cycle) and the physical features
(densitometry, porosimetry, water absorption, and durability (durability test)) implemented for
all samples. The results of the examinations showed that the mortar with compounds and mix
percentage (30% lime paste + 35% sand + 35% animal waste ash) has good resistance to aging,
freezing and thawing cycles, and salt cycle. The selected sample showed satisfactory results
after three durability cycles and was placed in a durable mortar class. Given the important role
of grading in the durability and quality of the mortar, the results obtained from the grading
diagram show that the pozzolan of the cow dung ash enjoys a proper grading than other
pozzolans. According to the results of the above research, it is proposed that the pozzolan-lime
mortars with the formula of 30% lime paste+ 35% sand+ 35% cow dung ash are used to
overcome the descending humidity and environmental corrosion in the architectural remnants of
the excavated historical sites in the cold climates, such as the ancient sites of the northwest of
the country to evaluate the results in practice as well. The results indicate this mix's efficiency in
the humid regions and salty regions near the wetting and drying cycles and freezing.
Mortar reversibility is another considerable point in using the coating mortars. Although
reversibility is not entirely possible concerning some protective measures and materials, such as
reinforcement and coating with polymeric materials in porous materials, the remarkable thing
about applying mortars to protect the architectural remains from its archaeological excavations
is that these mortars are suitable for reversibility. Their coating property depends on the depth
of penetration of the mortar adhesive in the substrate and because this penetration is not very
high (maximum 1 cm of slurry). Mortars use the substrate as a support in the coating state, and
the principal setting occurs in the mortar and its components. Therefore, their function will be as
a sacrificed layer in conservation. Based on the conditions of the studied mortars, in the case of
proper monitoring and solving the critical causes of the destruction of the selected mortar, it
seems that they will be efficient for at least five years. Finally, after the destruction process,
their surface can be reconstructed, or the coating mortar can be implemented again.
