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Abstract

This paper aims to characterize historical mortars taken from joints in Loom Factory site at Abydos Sohag (Egypt). This characterization includes their composition and technology, their state of preservation as well as provides a guide for their possible conservation process. A multidisciplinary approach has been adopted for investigations. Samples were investigated by means of visual inspection, polarizing microscope (PM), scanning electron microscope (SEM) coupled with energy dispersive X-ray unit (EDX), powder X-ray diffraction (XRD), hydrochloric acid (HCl) attack, sieving analysis, deferential thermal analysis (DTA-TG) and physical tests. Obtained results allowed to fully characterize mineralogical, chemical, and mechanical properties of selected mortar samples. They show a similarity of type, and binder/aggregate ratio. This similarity can be attributed to one building phase using the same source of materials.
97
Egyptian Journal of Archaeological and Restoration Studies "EJARS"
An International peer-reviewed journal published bi-annually
Volume 6, Issue 2, December - 2016: pp: 97-107 www. ejars.sohag-univ.edu.eg
Original article
CHARACTERIZATION OF HISTORICAL MORTAR USED IN LOOM
FACTORY SITE AT ABYDOS
Osman, A.1, Bartz, W.2 & Kosciuk, J.3
1 Conservation dept., Faculty of Archaeology, Sohag Univ., Sohag,, Egypt.
2 Institute of Geological Sciences, Wroclaw Univ., Wroclaw, Poland.
3 History of Architecture, Arts and Technology dept., Wroclaw Univ. of Technology, Wroclaw, Poland.
E-mail: amrosman75@gmail.com
Received 3/7/2016 Accepted 13/12/2016
Abstract
This paper aims to characterize historical mortars taken from joints in Loom Factory site at
Abydos Sohag (Egypt). This characterization includes their composition and technology, their
state of preservation as well as provides a guide for their possible conservation process. A
multidisciplinary approach has been adopted for investigations. Samples were investigated by
means of visual inspection, polarizing microscope (PM), scanning electron microscope (SEM)
coupled with energy dispersive X-ray unit (EDX), powder X-ray diffraction (XRD), hydrochloric
acid (HCl) attack, sieving analysis, deferential thermal analysis (DTA-TG) and physical tests.
Obtained results allowed to fully characterize mineralogical, chemical, and mechanical
properties of selected mortar samples. They show a similarity of type, and binder/aggregate
ratio. This similarity can be attributed to one building phase using the same source of
materials.
Keywords: Abydos, Loom factory, Mortar, Characterization.
1. Introduction
Loom Factory is located at
Araba al-Madfuna, about one kilometer
to the south of the famous temple of
Seti I in Abydos and about 47 km to the
south of Sohag (coordinates: 26°10'41
.28"N; 31°55'39.92"E). First excavations
at that site were done on February 1977
by the Egyptian Department of Antiquities.
The investigated area measures 700
meters (E-W) and 60 meters (N-S) [1].
According to excavators, it can be only
roughly dated back to the late roman
and Byzantine period. The main complex
of our interest is a small Byzantine loom
factory consisting of medium sized
peristyle, and a large hall attached to it.
According to Farrag, (1983) [1] a full
description of that site including the
thickness of the walls and applied
materials was given. No other additional
information about this place exist in
literature, except a paper mentioned the
use of pit looms at that site and
described them as a treadle pit [2].
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2. Materials & Methods
Since the building is relatively
small, only few representative samples
were taken from different remnants of
walls at four locations, which are still
visible on the site. All samples represent
jointing mortars and were carefully
taken with use of hammer and chisel,
from the western and southern walls of
building and from the unearthed two
loom pits. The map of the excavated
site and locations of samples are
presented in fig. (1-a, b) & fig. (2-a, b,
c, d). These samples have been prepared
to be investigated by the naked eye in
terms of color, state of preservation,
and visible aggregates. Thickness of
samples was measured already in situ
and rechecked once more in the
laboratory using digital calliper. In
addition, polished sections (ca. 45 ìm
thick) were observed by use of a stere-
omicroscope Zeiss STEMI 2000-C equ-
ipped with digital camera Canon
Powershot G10. Thin sections of intact
piece of each location were prepared in
a similar way, but with thinner slices
(thickness of ca. 30 ìm) for petrographic
analysis [3]. They were examined with
transmitted light polarizing microscope
(Zeiss Axiolab Opton) equipped with
Canon Powershot G2 digital camera
coupled to the microscope through an
eyepiece adapter. Few grams of each
sample, bulk as well as sieved (0.063
mm) and enriched in binder one [4, 5]
were prepared for powder X-ray diffra-
ction analysis. Both groups of samples
were analyzed with Siemens D 5005
powder diffractometer, using CoKá radiation,
at scanning speed 2è=2.0°/ min and 30
kV, 20 mA current [6]. Different miner-
alogical phases were identified using
PANalytical Xpert high score plus
software. For microstructural analysis,
samples were examined by scanning
electron microscope SEM-VEGA LSU
TESCAN, which was equipped with an
X-ray detector (EDX) (Oxford Inca-
pentaFETX3 detector). Binder/aggregate
ratio was calculated by separating visible
particles of lime lumps or carbonaceous
aggregates manually under stereomicro-
oscope, then by dissolving the rest of
sample in diluted HCl acid (2 Mol.
HCl) to separate insoluble aggregates
from the binder. Then, insoluble residue
was extracted and washed many times
until pH value of solutions was neutral
(pH=7). Then, they were dried and
weighed until they reached constant
weight. Finally, the particle size
distribution of insoluble fractions was
determined using dry sieving. The
remaining filtrate containing soluble
elements was chemically investigated
by means of atomic absorption spectro-
scopy (AAS) [7]. The quantitative
analysis of soluble elements was done
using a flame atomic absorption
Spectro-meter (FAAS) Avanta Sigma
GBC including elements Ca, Fe, Si, Al,
Mg, Mn, K, Na and Ti. Those elements
were converted into oxides before
cementation index (CI) was calculated,
according to the equation proposed by
Boynton [8]. In addition, the amount of
Cl- ions and SO3-2 were determined
using a colorimetric method [9]. Differ-
ential thermal analysis (DTA) and sim-
ultaneous thermo-gravimetric analysis
(TG) were carried out with apparatus
NETZSCH STA 409 Pc/Luxx with
crucible Al2O3 in nitrogen atmosphere
(N2) in the temperature range 40 °C - 1000
°C, with the heating rate 10 °C/min. Mass
loss of samples at certain temperatures
was determined, allowing us to
calculate amount of carbonates [10].
Physical properties of samples such as
moisture content, density, and porosity
were measured. Porosity was measured
using Gas Pycnometer AccuPycTM [11].
1330. For compressive strength tests,
samples were prepared by adding two
bars for the irregular samples [12-14]
and tested by device machine MTS 858
Mini Bionix.
99
--
Figure (1) Shows a. plan of the loom factory site (After Farag, 1983), b. general view of the site.
Figure (2) Shows locations of samples a. AN1 the southern wall of the site, b. AN2 from the western
wall of the site, c. AN3 from 1st loom pit, d. AN4 from 2nd loom
3. Results
3.1. Visual examination results
Results of examination by naked
eye and stereomicroscope revealed
similarity between all samples in terms
of grayish color, presence of various
and distinct components such as charcoal,
lime lumps, organic matters, and brick
fragments. All of them represent also
relatively good state of preservation.
Thickness of all samples is similar
ranging from 20.2 mm for sample AN2
that belong to the western wall of the
site, up to 23.0 mm for sample AN4
belonging to a wall of one of the loom
pits. Small amount of quartz grains was
observed in all samples. The investigation
results of the studied samples by naked
eye and stereomicroscope are summarized
in tab. (1). In addition, the samples
features and their polished sections are
shown in fig. (3-a, b, c, d).
a
b
a
c
d
100
Table (1). Results of visual examination of jointing mortar samples
Samples
locations Color Thickness
Avg. (mm) Charcoal Brick
fragments Lime
lumps Organic
materials State of
preservation
AN1 21.6 ++ + ++ +
AN2 20.2 ++ + ++ +
AN3 22.5 ++ + + +
AN4
Grayish
23.0 ++ + +++ ++
Coherent
(+++) Very abundant (++) Abundant (+) Rare (-) Not present
Figure (3) Shows a. sample AN1 from the southern wall (on the left) and photomicrograph of polished
section (on the right) showing presence of lime lumps and few small brick fragments, b.
sample AN2 from the western wall of the site and photomicrograph of polished section
showing big lime lumps as well as presence of charcoal pieces, c. sample AN3 from the 1st
loom pit (on the left) and photomicrograph of polished section (on the right) showing small
amount of quartz, d. sample AN4 from the 2nd loom pit (on the left) and photomicrograph of
polished section (on the right) showing presence of quartz grains, charcoal pieces as well as
rather big fragment of red brick.
3.2. Petrographic results
The results of the petrographic
analysis revealed similar mineralogical
components for all samples, including
rounded quartz grains as major constituent
of their aggregate. Some of them were
thermally transformed, strongly cracked,
healed and surrounded with thin silica
glass film. This feature is typical for
sample AN1 that belongs to the southern
wall. In addition, angular fragments of
limestone and abundant amount of large
lime lumps were identified, reaching up
to 4 mm in diameter, fig. (4-a). Brick
fragments are less abundant, but occurring
as a subordinate constituent in all samp-
les. Binding mass is not homogenous
consisting of micrite as well as lime
lumps. Charcoal is present and charact-
eristic for sample AN1, while fresh (i.e.
not pyrolyzed) organic matter (with
well visible structure of wood) is less
abundant. Cracks within the binder filled
with secondary weathering product (gy-
psum) were also observed. Uncommon
poly-crystalline grains of calcite were
observed in sample AN2, fig. (4-b).
Some of them are partly calcined; their
primary carbonate crystals are replaced
by micrite. In addition, the presence of
some other lithic grains of various rocks
such as granodiorite, and siliceous
sedimentary rock (cherts) were identified.
Sample AN3, fig. (4-c) differs a little in
comparison to other samples, being
depleted in limestone fragments and
lime lumps showing blurred boundaries
with surrounding binder mass. As accessory
minerals amphibole, garnet, K-feldspars
a
c
101
(perthite, microcline), plagioclase, glau-
conite and epidote were found in sample
AN1. In addition, sparse biotite, which is
strongly weathered to secondary chlorite
was detected, as for sample AN2,
amphibole, zircon, pyroxene, feldspars,
and epidote were detected, while sample
AN3 show amphibole; plagioclase, weat-
hered glauconite as well as fragment of
volcanic rock. Biotite, K-feldspars, epidote
plagioclase, and amphibole were identified
in sample AN4, fig. (4-d).
Figure (4) Shows thin section micrographs under plane polarized (left) & cross polarized (right): Field
of view is ca. 6 mm a. sample AN1 Lime lumps up to 4 mm, b. sample AN2, c. sample
AN3, c. sample AN4
3.3. Results of powder X-ray diffraction
X-ray diffraction results of both
bulk and binder samples are showed in,
fig. (5-a, b, c, d). For bulk samples
(AN1, AN3), obtained results revealed
calcite and quartz are the two main
phases. Vaterite and halite are present
as minor phases. The second group i.e.
mortars AN1 and AN3 enriched in
binder revealed calcite and vaterite as
main phases in both samples. Small amount
of quartz was present as remnants of
sieving in both samples. In case of
binder fraction of sample AN3, aragonite
was detected too.
Figure (5) Shows XRD pattern of AN1 samples a. bulk sample, b. fractions rich in binder & AN3
samples, c. bulk sample, d. fractions rich in binder.
b
d
Plane polarized Cross polarized
c
Plane polarized Cross polarized
a
Position [°2Theta]
20 30 40 50 60 70
Counts
0
100
400
900
1600
cal
cal cal
cal
cal cal cal
cal
cal
qtz
qtz
qtz
qtz
vat
cal
hal
vat
Calcite
Quartz
Vaterite
Halite
AN1
Position [°2Theta]
10 20 30 40 50 60 70
Counts
0
100
400
900
1600
cal
cal
vat vat vat
arg calvat
cal
qtz
cal cal
vat hal
cal
cal
cal
cal cal
qtz
Calcite
Aragonite
Quartz
Vaterite
Halite
AN1 (Binder)
a
b
Position [°2Theta]
10 20 30 40 50 60 70
Counts
0
400
1600
cal
cal
cal cal cal cal
cal
cal
calcal cal
qtz vat
qtz hal
vat hal
Quartz
Halite
Vaterite
Calcite
AN3
Position [°2Theta]
10 20 30 40 50 60 70
Counts
0
100
400
900
1600
cal
cal cal
cal
cal cal cal cal
cal
cal
cal
qtz
hal
vat
qtzvat
qtz vat
Calcite
Quartz
Vaterite
Halite
AN3 (Binder)
c
d
102
3.4. SEM/EDX Results
SEM/EDX observations of three
mortars from Loom Factory site revealed
various composition of a binder. Calcium
is its main component, however aluminum
and silicon occur in minor amounts, fig.
(6-a, b) especially in samples AN1 and
AN2 respectively. Some samples (mainly
AN3 from one of the loom pits) exhibit
high content of sodium and chloride,
fig. (6-c).
Figure (6) Shows SEM Microphotograph and EDX a. analysis for sample AN1bulk sample, b. analysis
for sample AN2, c. analysis for sample AN3
3.5. Results of acid attack
Results of acid attack for Loom
Factory samples were almost similar at
all levels, tab. (2). Percentages of
insoluble aggregates are identical and
lower than 50 %. They were as follows:
29.55 % for (AN1), 27.83 % for (AN2),
28.68 % for (AN3) and 29.14 % for
(AN4). Percentages of carbonates contents
range from 48.89 % to 52.30 %. Soluble
fractions are relatively high ranging
from minimum 18.56 % to maximum
24.97 %. As for cementation index (Ci),
all samples are below 0.15. Binder/
aggregate ratios revealed similarity of
samples AN2, AN3, AN4 with binder/
aggregate ratio close to 1.8:1 and
relatively lower ratio (1.5:1) in sample
AN1.
a
c
103
Table (2) Percentages of siliceous aggregates, carbonates, soluble fraction, cementation index, and
binder/aggregate (b/a) ratios.
Sample Carbonates % Insoluble
aggregates % Soluble
fractions % Cementation
Index (CI) B/A ratio
AN1 48.89 29.55 24.97 0.10 1.5 : 1
AN2 50.03 27.83 21.89 0.10 1.8 : 1
AN3 52.30 28.68 19.02 0.09 1.8 : 1
AN4 52.30 29.14 18.56 0.09 1.8 : 1
3.6. Results of AAS and Colorimetry
Results of AAS and Colorimetry,
tab. (3-a, b) revealed relatively high
percentages of chloride (Cl) in all sam-
ples, reaching the maximum values in
samples AN1 and AN2 (1.25 % and
1.28 % respectively).
Table (3-a) Results of chemical analysis of elements samples by AAS (converted to oxides)
Concentration % Sample
SiO2 Ca O Fe2O3 AL2O3 MgO MnO Na2O K2O TiO2
AN1 0.61 34.19 0.73 1.26 1.140 0.03 0.51 0.54 0.03
AN2 0.74 34.98 0.69 1.11 1.063 0.04 0.59 0.56 0.02
AN3 0.59 36.19 0.69 1.2 1.204 0.03 0.49 0.42 0.02
AN4 0.55 38.19 0.93 1.19 1.910 0.03 0.47 0.45 0.02
Table (3-b) Results of chemical analysis of samples by Colorimetry
Concentration measured by Colorimetry
Sample SO3
Cl
AN1 1.34 1.25
AN2 1.54 1.28
AN3 1.31 0.63
AN4 1.39 0.70
3.7. Results of thermal analysis
The results of this technique
reveal similar patterns of DTA/TG
curves. Sample AN1 (the southern wall)
reveals endothermic peak at 121.3 °C
related to possible presence of secondary
salts (gypsum). Carbonates show distin-
ctive endothermic inflections at 629.3
°C and 837.5 °C, fig. (7-a). Sample
AN2, fig. (7-b) (the western wall)
shows two endothermic peaks at 108.8
°C, followed by 143.6 °C referring to
presence of secondary product (double
step dehydration of gypsum). Decomp-
osition of carbonates was recorded at
638.3 °C. Sample AN3, fig. (7-b) (the
first loom pit) has also two endothermic
peaks, the first at 142.7 °C indicating
presence of possible secondary products,
and at 631.2 °C corresponding to the
release of CO2 from calcium carbonates.
Sample AN4 (the second loom pit) has
DTA/TG curves similar to sample AN3,
with too endothermic peaks at 143.7 °C
and 643.9 °C, fig. (7-d). All samples
have similar total weight losses and
very close percentages of carbonates
contents as presented in tab. (4).
Table (4) Weight loss per temperature range for mortars from Loom Factory site
Weight loss per temperature range %
Sample 0-200 °C 200-600 °C 600-900 °C Total weight
loss % Carbonates %
AN1 2.00 7.16 21.49 30.65 48.89
AN2 3.10 7.47 22.00 32.57 50.03
AN3 1.10 7.72 22.90 31.72 52.30
AN4 2.00 6.26 22.90 31.16 52.30
104
-
Figure (7) Shows DTA and TG curves of samples a. AN1, b. AN2, c. AN3, d. AN4.
3.8. Results of physical properties tests
The results of these tests are
relatively similar. Density values for all
samples are very close representing
1.21, 1.27, 1.30 and 1.24 g/cm3 for
samples AN1, AN2, AN3 and AN4
respectively. As for porosity measurem-
ents, the results of all samples ranged
from the minimum 34.1 % of sample
AN1 (the southern wall of the Loom
Factory) to the maximum 42.7 % of sample
AN4 that belongs to loom pit. These
measurements are presented in tab (5).
Table (5) Physical and mechanical measurements of Loom Factory site.
Sample Location Density g/cm3
Water
content % Porosity % Compressive
Strength (MPa)
AN1 Southern wall 1.21 3.47 34.1 -
AN2 Western wall 1.27 3.05 39.03 1.72
AN3 1st loom pit 1.30 2.89 34.22 1.83
AN4 2nd loom pit 1.24 3.46 42.7 -
Grain size distribution results,
fig. (8-a) have revealed that mortar
samples of Loom Factory have similar
distribution of grain size. The most
abundant fraction proportion for all
samples is 0.5 mm with percentages
23.10 %, 26.19 %, 24.14 % and 25.49
for samples AN1, AN2, AN3 and AN4
respectively. Cumulative curves for all
samples from Loom Factory site are
almost identical, fig. (8-b).
Figure (8) Shows a. Grain size distribution of mortar samples, b. Cumulative percentage curve for
mortar samples.
a
b
a
b
c
d
!!
105
4. Discussion
All samples from Loom Factory
present similar characteristics when
examined by naked eye, stereomicroscope,
and further analysis. Similarities between
different samples in terms of physical,
chemical, and mineralogical characteristics
which are rather typical as in sieving
analysis suggest that the whole building
has been erected during single construction
phase without further modifications.
The petrographic feature of abundant
lime lumps inclusions in combination
with their big size, may point to non-
sufficient calcination process, or imply
a hot lime mixing technology/dry slaking
method [15]. This observation leads to
the conclusion of dealing with material
of low quality and technology. Since in
the Loom Factory there is rather limited
need for water to be used, except perhaps
for cleaning purposes, the observed abundant
amount of charcoal may indicate rather
impurities coming from a kiln (remnants of
its fuel) together with burned lime but
not intentional use, to modify mortar
properties. Based on petrographical ch-
aracteristics, all samples have similar
mineralogical composition of the filler.
This indicates the same source of raw
material for the filler of all samples,
belonging to single building phase.
Presence of lime associated with organic
matter, ranging from fresh pieces to
typical charcoals in samples AN1 and
AN3 indicates to relationship between
presence of those various organic matters
and the appearance of vaterite phase.
That is reported in literature, that vaterite
may develop with time in a hot climate
enhanced by the presence of combustion
gases [16]. In addition, it was mentioned
that it can be associated with the presence
of the organic compounds, which were
added to the mixture, and their
degradation products as in stucco used
in Saint Peter basilica in Rome [17].
Their presence (i.e. organic compounds)
may lead to changes in other properties,
specifically, larger distribution of pore
size [18]. The presence of aragonite,
detected by means of XRD, could be a
result of the occurrence of bioclasts
(shells of mollusc or brachiopod). These
shells could be one of the components
of the aggregates, used as filler. Furthermore,
both aragonite and vaterite could result
from presence of furnace slag [18].
Some of those features and conditions
may apply to our case, specifically the
presence of various organic matter and
relatively hot climate. Detecting of
halite NaCl and observing its relative
high values refers to that site was
affected by salt (chlorides) crystallization.
As for cementation index (Ci), all
samples are below 0.15 referring to
using pure lime. Binder amount, which
is higher than amount of aggregates,
refers to abundant use of lime, which in
turn may refer to be obtained from near
local quarry at the west bank of the
Nile. That similarity in the results of the
thermal analysis stands in good agreement
with similarity in results of other kinds
of analysis of sample from Loom
Factory, confirming use of the same
materials, and pointing to one phase of
construction. According to the weight
losses of samples at certain temperature
range 600 °C - 900 °C, it can be concluded
that contents of carbonates in all mortars
are close to or equal 50 %. That indicates
using high amount of lime in preparation of
mortars. Similarity between all samples
in terms of density and porosity and
grain size distribution leads to similar
results of compressive strength tests,
suggesting the possibility of using the
same composition of mortar for head and
bed joints with no later amendments.
The relatively low values of compressive
strength for tested samples present rather
weak state of preservation.
106
5. Conclusions
The present study contributed with some observations, which may help in analysis of building
structure, specifically its chronology. Since all samples from Loom Factory site near Sohag
presented similar characteristics in terms of composition and manufacturing procedures, they
are possibly pointing to the fact that all the samples belong to one building phase using the
same source of materials. This work reveals significant aspect related to damage represented
by crystallization of salts which affects not only the mortar, but also the surrounding building
materials (red bricks and plasters). Gathered data of various characteristics have led to
documentation of its composition, technology, and damage aspects to composition of mortar
and its state of preservation as well as helping as a guide for further conservation works.
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... Regarding the presence of C, in sample (2) it mainly generates in two major forms (CO and/or CO 2 ) and it is due to firing of clays in conventional furnaces using fuels such as wood, charcoal, etc… as reported previously by Faria et al. [90]. The existence of Na and Cl in the most of the samples is related to salt contamination through effects of (NaCl) characterized groundwater dominated in Egyptian land [91,92]. Furthermore, the presence of sulphur (S) and phosphorous (P) with lower ratios prove the existence of their salts being buried in the soil and the presence of fly ash [14]. ...
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Many archaeological potteries in Sheikh Hamad (Athribis) Sohag, Egypt suffer from different processes, which led to many deterioration forms. Samples collected from Athribis were submitted to qualitative and quantitative measurements through using different techniques to evaluate their durability states. Significant information derived from these techniques prove that our materials are composed of Si, Al, Fe, Mg, K, Ca, Na and Cl as the main elements of Quartz Albite, Microcline, Calcite and Hemetite (main components of Nile clays) and Halite (main salt characterizes Egyptian land). In addition, SEM reveals that the samples are characterizes by cohesion of the granules, non homogeneous texture and different size pores in addition to degradation, dissolution features and cracks. Finally, it can be concluded that most of these artifacts are affected by two main aggressive mechanisms: their burial environment (before excavation) and aired environment (after excavation). These process that finally led to some aggressive deterioration forms.
... In addition to petrographic examination [32,41] and observations of the rate and course of leaching reactions of different mortars components [20], other criteria are also valuable in determining the reliability of 14 C mortar analysis. The first attempt to define a criteria was made by a team with almost 20 years of experience in mortars dating [14,36]. ...
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The methods of production of anthropogenic carbonaceous mortars makes them a valuable material for radiocarbon dating. The probability of successful application of ¹⁴C dating to mortars is related to the sample composition, not just the binder and added admixtures, but also the type, amount, and preservation state of the aggregate. The influence of different mortar components and applied pretreatments on dating results were demonstrated by ¹⁴C measurements on samples for which the preparation technique was either chosen on the basis of their composition or applied in an arbitrary and pre-defined manner. Mortars from 7 different locations are presented here (37 samples analysed and compared). The preparation procedures utilize mechanical and chemical selection of material for ¹⁴C measurements; collection of CO2 at different times, during decomposition in orthophosphoric acid, is applied to carbonates obtained, for example, from grain size selection or from different portions of forced suspensions. An important point is that aside from detailed analysis and applied preparation, the sampling of a mortar from a well-defined position, not suspected of any reworking, is crucial. In presenting ¹⁴C measurement results from different types of mortars and pretreatments, this paper illustrates the development of preparation methods over the years and the impact of their application on samples with different compositions.
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The design of new renders and repair mortars requires a certain knowledge about the mechanical properties of historic materials. The common problem is that the extracted samples of historic mortars often have an irregular shape not suitable for standardised physical and mechanical laboratory tests. This is for example a problem with the testing of bedding mortars from historic brick masonry and/or renders where a typical sample width is around 10-15mm. Typical samples from wall cores are mortar bulks of very irregular shapes. In addition to the various non-standard sizes and shapes there is often a need for minimum intervention which leads to minimalisation of samples in numbers and sizes. The experimental part describes testing of specimens made of irregular samples of historic and modern mortars in compression and bending. The key problem was obtaining a certain measurable shape. This was done by cutting of the sample or by adding some material. The determined properties are compared to the properties obtained from the tests on standard specimens. The methods of testing are discussed and evaluated.
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This paper aims to characterize lime based-binding mortars originating from ruins of industrial workshop associated with Anba Bishoi monastery near Sohag (Egypt) in respect to their possible conservation process. The ruins of the industrial part of this monastic compound are still neglected, while care has been given only to the church. Representative samples of binding mortar were collected from the well, adjacent walls, cistern, dyeing basins’ walls and cladding mortar of ceramic drainage pipes. A multidisciplinary approach has been adopted for investigations such as visual inspection, thin sections, SEM coupled with EDS, XRD, HCl attack, sieving analysis, DTA and compressive strength tests. Obtained results characterize mineralogical, chemical and mechanical properties of selected mortar samples. They show a diversity of type, and binder/aggregate ratio. According to the author’s opinion, this variety can be attributed not only to different building periods, but also to differences in building types and their functions.
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Historical evidence on the use of mortars to meet several needs has existed for millennia. With reference to the characteristic historical periods of the city of Rhodes, mortar sampling was performed on historical constructions, masonry and architectural surfaces. In the present work the different mortar technologies are investigated aiming to answer questions regarding their finality, i.e. whether their differences arise mainly from the various historical periods of construction or from the purposes they had to serve, imparting to the mortars the properties required by their function in the structure. Mineralogical, chemical, physical and mechanical investigations have been performed on characteristic samples after gradation. The exponentially declining function of the ratio CO2/H2O structurally bound to the CO2 content shows a continuous evolution of the kinetics governing the various mechanisms of carbonation of the binder or the formation of hydraulic components during setting, hardening and ageing of the mortars. The grouping of mortars in well-distinct ‘hydraulic levels’ is ascribed to the physico-chemical cohesion and adhesion bonds developed at the matrix and matrix/aggregate interfaces, respectively, allowing for the mortars to either bear continuous stresses and strains as joint mortars or provide compact impermeable renderings which harden even more on contact with water. Hence, parameters determining the diversification of the resulting mortar/matrix types concern the raw materials employed as binding materials and the production processing.
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In addition to the mineralogical characterisation of components of binder and aggregate in historic mortars, it is sometimes necessary to perform a chemical analysis on the materials in historic mortars. Acid dissolution/separation of binder from aggregate is the simplest method, and allows the determination of the chemical composition of the acid-soluble binder and, after separation, information on the mortar's aggregate. It is limited, when aggregate is acid-soluble. A range of significant analysis can be made including for soluble silica that relates to hydrated calcium silicates in the binder, and thus the hydraulicity of the binder. Other wet chemical analyses can be performed on the acid filtrate for soluble oxides of Fe, Al, Ca, Mg, S, Na and K. There may also be a requirement for the identification of organic substances, pigments and salts within a historic mortar. Chemical analysis forms a 2nd part of a possible scheme of characterisation of historic mortars that is presented as a flowchart. Chemical analysis also satisfies requirements for information input to conservation, repair and restoration works on historic buildings for the choice of compatible replacement materials. Corroboration of evidence of identification and quantification for chemical composition is best supported by a combination of methods, including mineralogical analysis methods. All methods of characterisation require qualified and experienced people to carry out the analyses.
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The mineralogical characterisation of historic mortars is performed for a number of reasons related to the conservation of traditional structures. The reasons for analysis and the questions posed during the conservation, repair or restoration of an old building determine the analysis methods that will be chosen. A range of mineralogical characterisation methods is available for the study of historic masonry mortars. These include X-ray Diffraction (XRD), Optical Microscopy, Scanning Electron Microscopy (SEM), Thermal and Infra-Red methods. Sample preparation is important; adequate separation of binder from aggregate is required for instrumental as opposed to microscopic investigation methods. An ordered scheme of analysis can be developed and is presented in flowchart form. It is difficult, and perhaps unwise, to analyse a mortar with only one method of characterisation. Corroboration of evidence of identification and quantification for mineralogical composition is best supported by a combination of methods, including chemical analysis methods. All methods of characterisation require qualified and experienced people to carry out the analyses.
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This research focuses on the characterization of nineteenth century hydraulic restoration mortars used in the Saint Michael's Church in Leuven (Belgium). The mortars were used as restoration mortars for weathered mortar joints. A historical study of old work descriptions and mineralogical, petrographical and chemical analyses have been used to characterize these hydraulic mortars. The different hydraulic phases are identified using petrographical analysis, X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectrometer (EDX) and chemical analyses. Based on the presence of gehlenite (C2AS), the dominance of C2S, the large amounts of portlandite, the chemical analyses and on the historical sources, these hydraulic mortars are characterized as natural hydraulic lime mortars.
Excavations at Abydos in 1977: A Byzantine loom factory
  • R Farag
Farag, R., (1983). Excavations at Abydos in 1977: A Byzantine loom factory, Mitteilungen des Deutschen Archäologischen Instituts Abteilung Kairo, Vol. 39, pp: 51-57.
The missing link: Filling the gap in the evolution of medieval domestic looms
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Ball, J., (2009). The missing link: Filling the gap in the evolution of medieval domestic looms, in: Alchermes, J., Evans, H. & Thomas, T. (eds.) ÁíáèÝìáôá ÅïñôéêÜ: Studies in Honor of Thomas F. Mathews, Mainz, pp: 40-46.
A code of practice for the petrographic examination of mortars, plasters, renders and related materials
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Leslie, A. & Eden, M., (2008). A code of practice for the petrographic examination of mortars, plasters, renders and related materials, Technical report, Applied Petrography Group, UK.
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Middendorf, B., Baronio, G., Callebaut, K., Hughes, J., (2000). Chemicalmineralogical and investigations of old mortars. In: RILEM (ed.) Proceedings of an International Workshop Historic Mortars: Characteristics and Tests. Paisley, pp: 53-61.