ANALYSES ON BUILDING MORTAR SAMPLES USED IN THE WORKS OF MASONRY
OF THE JASOS ARCHAEOLOGICAL SITE, TURKEY.
P.Pierattini 3
a Dipartimento Scienze della Terra, Via La Pira 4, 50100 Firenze - pierattini@steno.geo.unifi.it
Keywords: Archaeological Heritage Conservation, Survey and Mapping, Data collection Information Technology
Abstract
Mineralogical and petrographical analyses of mortar samples coming from different stratigraphic units of the walls,have been
attempted. The importance of a deep knowledge of the materials used as mortars in the works of masonry is due to the need of
characterising their composition and quantifying the percentage of the different components, suche as aggregate and/or binder.
The comparison of the samples and the evaluation of data from both excavation samples and stratigraphical analyses of the walls
could allow to define relative or absolute chronologies. These temporal data could be useful for the study of manufacts of the lasos
archaeological site. The large use of these methodologies in the survey could add useful information on both the technological
processes and on the sites the studied materials come from. The research will also represent an important documentation for a reliable
chronological reconstruction of the different phases of development of the ancient urban site.
1. Analytical methodologies
The analytical methodologies used for the purpose follow the
UNI-NORMAL 12/83 rules (artificial aggregates of clasts with
a not clayey binder matrix: scheme of description).
Materials have been described and classified through the
observation of thin sections - thin sections are 30 micron thick -
. The observation are made through an optical microscope at
trasmission light. The observations allow to recognize both
mineralogical, and textural and structural differences among the
samples.
The mineralogical and petrographical description of the samples
follows. Photos of thin sections are enclosed.
2. Results
Sample UF10 USM3: mortar made of an aggregate with a little
omogeneous granulometry, not oriented, omogeneously
distributed and with dimensions between 50 micron and few
millimeters. The mineralogical anlysis suggests the presence of
vulcanic and sedimentary rocks - sandstones -. The vulcanic
rocks have a porfiric structure, with fenocrystals included in a
microcrystalline to vitreous ground mass. Brick fragments are
also present. The granes of the aggregate have different forms
and are quite rounded. The aggregate/binder ratio is high -
about 50% - , and the adhesion of clasts and binder along the
grain boundary is good. The hazel binder is quite omogeneous;
its composition is calcitic, with micro-cristalline dimensions;
some lumps are also present. Many pores of different forms and
dimensions occurr; porosity is high and shrink fissures are rare
(See Fig. 1-2).
Sample UF1 USM6: mortar made of an aggregate with a little
omogeneous granulometry, not oriented, omogeneously
distributed and with dimensions between 50 and 100 micron
and few millimeters -this fraction is less abundant -. The
mineralogical analysis suggests the presence of quartzose-
micaceous to carbonatic rocks -calcschists -, brick fragments
and parts of microorganism shells. Polycristalline quartzose
crystals and rare felspars also occurr. The granes of the
aggregate have different forms and are generally well rounded.
The aggregate/binder ratio is made by 30-40% aggregate and
60-70% binder, and the adhesion along the grain boundary of
clasts and binder is good. The binder is not omogeneous, with
dark hazel colourportions; some lumps and cooking remains are
also present. The binder has a calcitic composition, and the
texture is from cripto- to micro- crystalline.Many pores of
different forms and dimensions occurr; porosity is quite high
and shrink fissures are also present (See Fig.3-4).
Sample UF10 USM1: mortar made of an aggregate with a
little omogeneous granulometry, not oriented, omogeneously
distributed and with dimensions between 50 micron and few
centimeters. The mineralogical anlysis suggests the presence of
calcschists, arenaceous fragments, rare carbonatic fragments,
some brick fragments and parts of microorganism shells. Quartz
and feldspar crystals are also present: quartz crystals are often
policrystals with wavy extinction. The granes of the aggregate
shows many different forms and are generally well rounded.
The aggregate/binder ratio is made by 30-40% aggregate and
60-70% binder, and the adhesion along the grain boundary of
clasts and binder is scarce. The binder is characterized by a
quite omogeneous hazel colour alternating with pale grey bands;
lumps also occurr. The binder is calcitic, and the texture is
micro crystalline. Many pores are present; porosity is quite high
and many shrink fissures also occurr (See Fig.5-6).
Sample UF1 USM5: mortar made of an aggregate with a little
omogeneous granulometry, not oriented, omogeneously
distributed and with dimensions between 100 micron and few
millimeters. The granulometric class of about 100 micron is
scarcely represented; the most represented one is that between
about 200 and 600 micron.The mineralogical anlysis suggests
the presence of calcschists, arenaceous rock fragments and rare
carbonatic fragments. Rare brick fragments and parts of
microorganism shells also occurr. Quartz and feldspar crystals
are also present: their dimensions are between 200 and 400
micron. Quartz crystals are often policrystals with wavy
extinction. Crystals have different forms and are generally
subrounded and/or subangular. The aggregate/binder ratio is
about 40-50% and the adhesion along the grain boundary
between clasts and binder is quite good.. The binder is
characterized by a not omogeneous colour and apparance, with
the presence of lumps. The dominating colour is dark hazel; the
binder composition is calcitic, and the texture is micro
crystalline. Many pores with different forms and dimensions are
present. Many shrink fissures also occurr in correspondance
with lumps (See Fig.7-8).