12TH INTERNATIONAL

BRICK/BLOCK Masonry c O N F E R E N C E

Fio

ANAlYSIS OF OlD MORTARS FROM ANCIENT AGORA OF THESSAlONIKI, GREECE

Florez de la Colina, M. A. 1; OK, 1. 2

ABSTRACT:

This paper is written with the information contents of the Analysis of Old Mortars from the Ancient Agora of Thessaloniki in Greece, done during the 1st International Cour­se on the Conservation of Andent Masonry in Byzantine Architecture, held in the­Technical School, AUTH, from August 17 to October 10, 1998, with the colabora­tion of ICCROM. The purpose of this analysis is to study the characteristics of the old mortars, to be able to establish the parameters to design a repair mortar. The mortars which are stu­died here are used mainly as renders or coat of the margarita shaped baths founded in the Ancient Agora (3rd. century A. O.)

Key words: Masonry restoration, repair; Mortar; Masonry training, education; Heri­tage.

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1. INTRODUCTION

1.1 Historical facts

In 168 ad. I.C, after the battle at Pydna lost by the Makedonian King, Thes­saloniki surrenders to the Roman Consul Paulus Emilius. It is the begining of the Roman control over the city. From this period, there are some important buidings and other remains which have reached us though the barrier of time: Rotonda, Galerius Arch, some remains of the Hyppod rome, some parts of Ga­lerius Palace complex located in Gounari street and Navarinou square, some parts of the city walls used in the Byzantine period, and a part of the Roman Agora .

Excavations have being carried out in the Ancient Forum in the past eight ye­ars (1989-1997), and are still going on. The part which has been excavated and is now under restoration work, being located near Dikastirion square, and clo­se to Via Egnatia, a major road bui lt between 146 and 120 BC communicating Thessaloniki with both the Balkans and the Black Sea. The large agora or forum covered two hectares around a paved courtyard, leaving open the north side. Built in the second century AD, the main period is considered to be the 3rd. century A.D .; in early Byzantine Period the ancient agora was no more than a rich quarry.

The setting of this part of the city, does not seem to be the best for a Forum. The diagonal fali towards the south-east corner leads to urban complexity. A crypto­porticus was built and also two leveis of streets, one of them being 3.3m below the portico floors and the other at the higher levei on the south side. Our sam­pies are taken from the margharita shaped bath, found below Agn .Stratiotou and Filippou streets, in the area located in the south-east of the excavation.

1.2 Building techniques and materiais

The unexpected find of this unique bath, makes it difficult to relate it to other buildings , and it is not our purpose to do so, except, may be , in relation to the building techniq ues and materiais used in Late Roman Times.

The "banieras" are disposed between two concentric circles, with a stone frag­ment mosaic in the floor of the inner circle. The same floor is found connecting the two diameter opposed access to the bath, in a line paralle l to Agn. Stratiotou street. In the central point, again, there is a circular shaped elevated base.

The bath enclosure is now made of stone masonry walls, rectangu lar shaped, which seem to be from a later period due to the fact that they are built over a part of the "banieras". In the circular part of the externai circle inside wh ich the "banieras" are located, there are traces of a vertical rendering (2-3 cms high), which look quite similar at first sight to the render used in the "banieras".

The shape of the "banieras", organized as it is said above in a circular shaped pat­tern, is achieved by using both bricks and mortar. Then severa I layers of different kinds of render are applied to obtain a smooth, waterproof surface. The coat is done using several layers of lime mortars, with a technique quite well known and documented, as a water proofing system.

2. DOCUMENTATION OF SAMPLES

2.1. Location of samples

The exact location of the seven samples brought to the Civil Engineering School was not known with precision . A visit to the site, with the indication of the area from which the samples were taken by the person who had done it, allows us to relate the samples with the different layers of mortar, based on the visual inspec­tion already done on the samples.

In order to relate our work to the Program already developed by the Division of Structural Engineering, from the Civil Engineering School of Aristotle University of Thessaloniki, to develop a Data Base with the Characteristics of Old Mortars studied with the NATO sponsored Program, we have filled in the Forms developed in their Laboratory by Mrs. I Papayianni. Unfortunately, not ali the data of the samples was available; 50, some of them are missing from the file. We have also taken a photo of each of the samples given to us, with a scale and their reference code (given to them on site) in each of them, with the Greek reference translated to English.

2.2. Visual observation

Visual inspection give us the first information about the samples. It provides a background on similarities and differences between samples, which allows some basic ideas on how the samples should be tested .

The results of visual observation for the seven studied samples, have being des­cribed as follows:

• SAMPLE 1 A: Ancient Agora rendering mortar, from the bath . Number of items: one bigger piece and another smaller. Colou r: light pink. Size and type of sam­pie: the bigger piece has a 3 mm thick layer (Iight pink colou r), with very good bond with a mortar layer (white grey colour, as described in sample 2 A); thick­ness on pink layer is quite homogeneous. Other remarks: easy to break by hand, very well worked surface on pink layer with a thin layer of white coating but only in some areas of this surface, aggregate distribution appear to be homogeneous and with visible brick fragments.

• SAMPLE 2 A: Ancient Agora, layer under rendering mortar, from the bath. Number of items: severa I pieces. Colour: white grey. Size: piece around one to

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two centimeters and smaller, ali seem to be from the same kind of composition. Other remarks: easy to break by hand.

• SAMPLE 3 A: Ancient Agora, structural mortar of the bath, under layer A. Num­ber of items: one bigger piece and two smaller ones. Colour: pinkish mortar co­vered with brownish layer (seems to be earth), non homogeneous in colou r on surface (some pinkish, some brownish areas). Size: pieces around three centime­ters and smaller, ali seem to be from the same kind of mortar composition. Other remarks: not 50 easy to break by hand.

• SAMPLE 4 A: Ancient Agora, structural mortar of the bath, under layer B. Num­ber of items: severa I pieces. Colour: whitish pink mortar. Size and type of sample: pieces around three centimeters and smaller, ali seem to be from the same kind of composition. Other remarks: breakable by hand.

• SAMPLE 5 A: Ancient Agora, white thin coating over pink mortar of the bath. Number of items: powder. Colour: whitish. Type of sample: non consistent. Ot­her remarks: breakable by hand. [Thin coating 0.1 mm thick, applied on the sur­face of reddish / pink layer, found in samples 1 A and 1 M]

• SAMPLE 1 M: Ancient Agora red mortar rendering of baniera, from the bath. Num­ber of items and size: several samples of two types, some bigger (up to 1.5 cms.) and others smaller, non homogeneous and with two layers of mortar in the same piece. Colour: pink with rough surface, white and rougher behind (most of the pieces); pink with even surface, white and rough behind. (two to tree small pieces). Type of sam­pie: the pieces have a 3 mm thick layer (pink colour), with very good bond to a mor­tar layer (whitish colou r); thickness on pink layer is quite homogeneous in samples with even surfaces, but varies very much (0.9 tol.9 mm) on the others. Other re­marks: easy to break by hand, aggregates distribution seems homogeneous and with visible brick fragments, specially in samples with rougher surface.

• SAMPLE 2 M: Ancient Agora, white mortar layer under rendering of baniera, from the bath. Number of items and size: several pieces, up to 2.5 cms. Colou r: light grey, with stains of brownish colour. Type of sample: pieces seem ali from the same kind of composition. Other remarks: easy to break by hand.

• SAMPLE 3 M: Ancient Agora, structural mortar of the baniera, from the bath. Num­ber of items: one piece, triangular shaped, and some powder. Colou r: pinkish morta r covered with brownish layer (seems to be earth), non homogeneous in colour in sur­face (some pinkish, some brownish areas). Type of sample: ali pieces seem to be from the same kind of composition. Other remarks: not 50 easy to break by hand.

3. EXPERIMENTAL ANALYSIS: PHYSIC AND MECHANICAL CHARACTERISTICS

Experimental analysis gives us deeper information about the samples. It can con­firm or reject the first impressions provided by Visual Observation.

In order to determine the physical and mechanical properties of old mortars and plasters, density, porosity, water absorption, compressive strength and adhesion should be studied. There is not a standard procedure to test them and if you try to apply a method used to test other similar new materiais, one of the problems you may find is the difficulty in cutting a standard sample from the mortars of an old structure, or those due to a crumbling state of the mortars. Aesthetic reasons and conservation ideas may also be a problem if you want to preserve the origi­nai materiais which were used and not only the building methods or the shape of the remains found on the archaeological site.

3.1. Microscope observation

This analysis can be done with different kinds of equipment: in the Reinforced Concrete Laboratory of Civil Engineering School, AUTH, we have used LEICA WILD M-10 stereoscope.

The results of microscope observation for the seven first studied samples, and tho­se of the new samples brought to us after to complete our analysis, have been described as follows.

SAMPLE 1 A: Ancient Agora rendering mortar, from the bath.

• matrix: some white nodulous which look like lime; cracks on so­me of them with secondary crystallization around the crack; ma­trix is based on lime (content approximately: 25%; must be con­firmed by further analysis); some pieces of the smaller samples have thin cracks (80 magnification).

• aggregates: type: brick (20%) and brick dust (12.5 magnifica­tion): quartz (8-10%); small amount of charcoal; some small amounts of stone; shape: uneven.

• other remarks: greenish colou r stains which look like biological at­tacks on the surface; thin coating which looks like some protec­tion, detached from surface; very thin fibers at the side of the sample can be found with 80 magnification.

SAMPLE 2 A: Ancient Agora, layer under rendering mortar, from the bath.

• matrix: cracks in it; poor quality; quite porous; lime concentration and cracks due to unslacked lime; cracks between aggregates and binding medium.

• aggregates: size: with big particles up to 0,9mm x O.4mm, dark grey; smaller particles 500mm; type: quartz: small amount of char­coai; some darker colour (could be volcanic); shape: uneven; "suba­rrotondo", from "molto bassa" to "alta"; total amont: around 40%.

• other remarks: biological grows ( like flowers).

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SAMPLE 3 A: Ancient Agora, structura l mortar under layer "A", from the bath.

• matrix: horizontal cracks parallel to surface; cracks perpendicular to surface w ith earth inside but not crystals; white colour "sheet" shaped cracks; secondary re-crystallization near the surface and in cracks; lime nodulous and cracks due to unslacked lime; good, compact bond between aggregates and matrix; lime, about 30%.

• aggregates: type: sand , about 5 mm maximum size, brick, about 1 mm max. Size; total amount brick and sand: 10%; charcoal, small amount, different sizes; shape: uneven; "subarrotondo", from "molto bassa" to "alta".

SAMPLE 4 A: Ancient Agora, structural mortar under layer "B", from the bath.

• matrix: many cracks, specially in areas where lime is concentrated (unslaked lime); in some places, contact with aggregates is not good; lime, about 30 % to 35 %; brick dust used as filler; max. pore size: 85.4 Ilm length; 30.22 Ilm width; mino pore size: 35.21 Ilm length; 16 Ilm width

• aggregates: type: sand, quartz 4 to 5 Ilm maximum size; brick, small amount: about 2.5 to 3 mm max. Size; total amount brick and sand: 30 to 35 %; charcoal, about 2 mm max. size.

• other remarks: re-crystallization orientated in "stripes" ("macro­orientated", you can see orientation even w ith the naked eye).

SAMPLE 1 M: Ancient Agora red mortar rendering of baniera, from the bath.

• matrix: accumulated white crystals on outer surface (not in con­nection with inner layer); contact between matrix and aggrega­tes very good.

• aggregates: type: brick (25%) up to 1.5 mm size and brick dust; small quartz crystals; unslaked lime or crushed limestone used as aggregate, about to 5%; small amount of charcoal.

• other remarks: "jelly" coating on the surface, as in sample 1 A.; con­tact between two layers of sample seems good; very thin fibers, as in sample 1 A; brick used as filler (dust), and as aggregate (bigger size)

SAMPLE 2 M: Ancient Agora, white mortar layer under rendering of baniera, from the bath.

• matrix: cracks in it, small and big; quite porous; cracks inside po­res; lime amount about 35%; fibers, as in sample 2 A.

• aggregates: type: sand from 500l1m to 5-6 mm; quartz; colour: from greenish to brownish; total amount: around 40 to 45%.

• other remarks: biological grows (Iike flowers) , as in sample 2 A.

5AMPLE 3 M: Ancient Agora, structural mortar of the baniera, from the bath.

• matrix: big pores with secondary re-crystallization near the surfa­ce and in cracks; cracks in matrix; in some big pores, the matrix is pinkish and totally cracked; good, compact bond between ag­gregates and matrix.; white lime nodulous; lime, about 30 to 35%; max. pore size: 132.52 11m length; 71,94 11m width; fine pore size: 100 11m

• aggregates: type: river sand , about 15 to 20%; brick, about 7 to 10%; shape: uneven, broken pieces (green stone); charcoal, small amount.

• other remarks: some pieces with rust colour stains around them in the brownish areas.

3.2. Mechanical strength

To have a better understanding of the quality characteristics and durability of old mortars, mechanical test should be carried out.

This test is done using a 4 x 4 x 4 cms sample, filling the mould if necessary with gypsum. If the sample is too small, results are not reliable. If the mortars are di­saggregated, it is almost impossible to cut standard size samples to test mecha­nical properties. Some of our samples were too small to provide accurate results. Most of them were only small fragments, breakable by hand or even powder. 50, we could not realize Mechanical strength Tests.

3.3. Porosity

Porosity has a great influence on properties of ancient materiais used on masonry. Permeability, related to high porosity, can create problems due to water absorption and freezing conditions, causing stress inside the material. Several ways can be used to measure porosity: One of them is Mercury Porosimetry, which gives us total po­rosity as well as pore size distribution. A simple way to obtain porosity characteristics, is the Water Absorption method. The quickest, but also less reliable system, is th­rough Image Analysis, which should only be used for pores larger than six microns.

As we are dealing with small amounts of samples, we have used Water Ab­sorption measured with Vacuum Method, according to RILEM CPC 11.3, to

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obtain Open Porosity. With this system, we should proceed as follows: The samples are dried in an oven at 105 - 110 00 C, and the weight is measured until it is constant. After that, the samples are placed in the desicator and the air is evacuated by a vacuum pump, to a steady state which has been reached on manometer indication. Then, the pump is disconnected and the water is allowed to enter in the container by atmospheric pressure, until the sample is completely covered with water. After 24 hours of being soaked in water, wa­ter saturated samples are taken out and weighed with spring balance. Then, the samples are dried quickly and measured in dry air, which allow us to ob­tain their volume.

Porosity and specific gravity are calculated using the following equation:

% Porosity = (B2 - B1 / B1) x 100 • B1 = dry weight (gr.) • B2 = surface dry saturated

specific gravity (gr./ cm 3) = B1 / B3

• B3 = equivalent weight of water to volume of the sample

From our samples, only four of them were consistent enough to be able to use them to measure porosity (3A, 4A, 2M, 3M). The others didnrtt allow measure­ments to be taken.The results of the four samples analysed are shown in the ta­ble:

Table 7. Physical Properties: Porosity and Specific gravity.

Sample Code: Porosity %

2M 18.48

3/\ 29.34

3M 24 .08

4/\ 15.96

Graphic for comparison of porosity between samples.

35 30 25 20 15 10 5 O

2M 3 3M

Specific Gravity gr/cm'

1.1 94

1.327

1.384

1.241

4

As there was not enough sample for testing and samples which were available were crumbling, it was not possible to measure porosity on ali samples.

3.4. Sieve analysis

Sieve analysis is done to obtain information on size distribution of puzzolanic ma­teriais which are used as fillers and additives, and also on the siliceous aggregates content. This analysis requires 10 grs of sample which is dried in a climatic cham­ber at 105°C temperature and then is put in diluted HCI (hidrocloric acid) solu­tion for 10-20 hours. After the dissolution of binding medium, the solution is ex­tracted through black bloating paper and is washed with distilled water to eliminate chlorite. Then the insoluble part is dried again in a climatic chamber at 105°C and the total remaining insoluble part is measured before the sieving pro­cesso Gradation is achieved by using 4mm, 2mm, 1 mm, 7S0~m, 300~m, lS0flm, 75~m, 4SIlm sieve size. Results obtained are as follows:

Table 2. Relative humidity and insoluble parts after acid testo

Sample Code: % RH % Insoluble < % Loss

1M· 1.6 46.27 52.13

2M· 3.5 31.47 65.02

3/\· 1.9 45.14 52.95

Table 3. Partic/e Size Distribution. Samples are dissolved in % 10 HCL, insoluble parts are sieved and graded.

Sample 4mm 2mm 1 mm 750~m 300~m 150~m 75~m 45~m

(ode:

1M· 11.58 23.17 9.87 21.8 15.45 12.44 7.72

2M· 8.85 28.11 24.04 10.76 18.06 6.1 2.9 1

3/\· 12.06 30.96 12.63 22.43 13.11 6.47 2.36

Note: These three samples which are used for this test are brought from the archaeological site later due to the lack of samples being brought before, and are considered to be taken from the same place as the first samples 1 M, 2M, 3/\

Table 4. Total retained, total amount and total percentage of passing for 7 M, 2M and 3L after acid analysis.

1M· 311· 2M·

Sieve size Total T.w. 01 T.%ol Total T.w.of T.%of Total T.w.ol T. %01 Retained passing passing Retained Passing passing retained passing passing

4mm 0.74 7.62 91.95

2mm 0.27 2.11 88.66 0.76 5.57 87.99 3.09 5.27 63.04

1mm 0.81 1.57 65.97 2.72 3.61 57.03 5.1 3.26 38.99

750~m 1.04 1.34 56.30 3.52 2.81 44.39 6.0 2.36 28.23

300m~m 1.55 0.83 34.87 4.94 1.39 21.96 7.51 0.85 10.17

150~m 1.91 0.47 19.75 5.77 0.556 8.856 8.02 0.34 4.07

75~m 2.2 0.18 7.56 6.18 0.15 2.37 8.27 0.09 1.08

45m~m 2.38 6.33 8.36

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Table 5. Camparisan af the Characteristic af the three Martar Samples After Acid Test:

Sample Code: Binder Aggregate ratio: Characteristic of the Aggregates: (after acid test)

1M' 1.1; 1 size distribution from 2mm up to 150l1m. Mostly brick agg regates some of them covered with earth ar clay, crushed green stone aggregate (gneiss), and approximately lame amount of river sand , in smaller particles few grai ns of cha rcoal.

2M' 2; 1 Size distribution from 4mm up to 150 11m. Higher amount of river sand and crushed green stone. Some altered fragments.

3Á' 1.1; 1 Size distribution from 2mm up to 150l1m, approximately same amount of crushed brick and crushed green stone, and higher amount of river sand.

Pet rografic analyses have a great importance on studying t he minera logical structure and characteristics of heterogenous materiais such as mortars, plas­ters, some ki nd of stones ... It can be done on the samples prepared w ith the above described proced ure. It is important to know, the acid dissolved binding medium is not the only lime but can be also the crushed marble used as ag­gregate. For this reason, it is very convenient to complete this analysis with the information provided by petrografic analysis on Thin Sections prepared with other pa rts of the same sample. Unfortunately, the lack of samples and the ti­me available didn't gave us t he possibili ty to prepare t hin sect ions for this study.

Petrograf ic analysis of insoluble parts under binocu lar microscope have being al­so done to the three samples prepared with Hei for sieve analysis with the foi 10-wing resu lts:

Table 6. Observatian af Insaluble Parts Under Sterea Micrascope (Wild MIO).

Sample Code: 4mm 2mm 1mm 75011m 3OO11m 15011m

1M' brick aggregate brick aggregate, brick aggregate, same amount of higher proportion and some brick some gneiss and same amount of brick, quartz and of brick, sma ll aggregate some quartz quartz and gneiss, gneiss small amount of covered with some earth amount of feldspar, mica may be earth particles. feldspar and and charcoal, or clay lilosi licates (mica also some

and muscovit) feldspa r.

2M' same amount of few grains of same amount of higher amount 01 95% 01 si liceous high amount 01 gneiss and some quartz, high si liceous gneiss, some aggregate, few siliceous altered fragment amount of gneiss aggregate and quartz and gneiss aggregate aggregates. which are not and some non gneiss feldspar few and some musco distinguishable. distinguishable fi losil icate

fragment.

3A' brick, quartz and mainly si liceous brick aggregate, same quantity of mostof it is gneiss material brick quartz, feldspar brick and gneiss, si liceous material,

aggregate and and some gneiss. leldspar and some grains of high proportion quart brick and few of gneiss grains of charcoa l.

4. CHEMICAl ANAL YSIS

4.1. Salts content

The most common and most destructive soluble salts found in old masonry ma­teriais are sulfates (S04-), nitrates (N03-) and chlorides (CI -), which by dissolu­tion and re-crystallization can cause cracking, powdering, pitting . The main sour­ces provoking the destruction on masonry can come from cement used in later restoration, air pollutants, sea water, burial sites ...

The chemical analysis for measuring the soluble salts contents in seven samples is carried out by using hight performance liquid chromatography "HPLC". Samples are grained and a small quantity (1 gr.) of filler (75~m) is taken and dissolved in distilled water. Solution is kept mixing for two hours on magnetic mixer; then the solution is filtered and diluted up to 250 mio A small quantity of solution (1 mio) is taken and injected in the cationic column (solid phase) with the eluant solution (mobile phase).

The results are calculated in Metric System Units from the chromatogram of sam­pie in relation to a standard chromatogram. The quantitative amount of salts is obtained in percentage by the following equation :

wt % = (C . d v. df / W sample) x 0.0001 • C = concentration of the anion (gr/I) • v = volume of undilluted sample solution (mio) • W = sample weigh (gr.) • df = dilution factor

Results obtained are given in table 7.

4.2. loss of ignition

For measuring the amount of calcium oxide (CaO) and indirectly silicium oxide (Si02) in the sample, the loss of ignition test is carried out. A small quantity of fi-

Toble. 7 Soluble 50ft Contento

SALTS W.t %

Sample Code: (I SO"4 NO,'

lA 0.04 0.08 0.009

2A 0.32 0.006 0.12

3A 0.02 0.053 0.022

4A 0.04 0.11 0.05

1M 0.04 0.13 0.04

2M 0.02 0.03 0.013

3M 0.02 0.02 0.04

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lIer (1 gr.) is put in oven at 1000 °C until its weight becomes stable. After that, the sample is taken out and weighed again . The ignition loss percentage is calculated w ith the following equation:

I.L.% = (W1 - W2 / W1) x 100 • W1 = f irst weigh • W2 = weigh after ignition loss

The results are given in table 8a.

4.3. Atomic absortion

Determination of composition of old mortar in oxides such as Si02, AI03, Fe203, CaO, MgO, Na20, K20, has been done by using sim pie beam Atomic Absorp­tion spectrometer. The results obtained by this instrument is given in concentra­t ion (ppm) and then calculated by equation given below in order to have weight percentage:

wt % = (C x V x df) / w x 0.0001

Table 8a. Chemical Analysis by Atomic Absorption.

DISSOLVED IN AClDS W.t %

Sample Na,O K,O CaO MgO Fe,O, AI,O, SiO, L.I %

Code:

lA 1.294 1.228 35.39 1.724 3.66 8.01 19.9 28.8

2A 1.509 0.795 39.31 1.575 3.20 3 7.48 22.3 23.8

3A 1.186 1.951 30.64 2.122 3.489 8.50 30.4 23.5

4A 1.213 1.06 45.33 1.343 1.972 5.59 10.6 32.9

1M 1.34 7 1.325 32.74 1.84 3.574 7.9 27.6 23.7

2M 1.833 0.795 36.37 1.674 3.374 7.93 23.3 24.7

3M 1.024 1.638 26.86 3.4 3.43 8.16 30.1 25.3

5A 0.277 0.09 55.26 1.558 0 .180 1.09 0.11

Table 8b. Chemical Analysis by Atomic Absorption.

DISSOLVED IN 0.1 N W.t %

Sample Na,O K,O CaO MgO Fe,O, AI,O, SiO,

Code:

lA 0.21 0.63 23.6 0.50 0.52 2.04 1.17

2A 0.23 0.43 28.3 0.32 0.321 1.28 0.75

3A 0.25 1.23 19.6 0.84 0.79 3.1 9 1.31

4A 0.24 0.40 38.3 0.47 0.158 0.72 0.46

1M 0.17 0.52 25.0 0.49 0.488 2.10 1.06

2M 0.20 0.43 25.5 0.31 0.388 1.59 0.67

3M 0.21 0.94 20.0 1.79 0.577 2.87 1.44

5A 0.07 0.09 52.5 1.04 0.021 0.36 0.06

A small quantity of samples filler whieh is taken after sieving, is disolved in dilu­ted hydroehlorie aeid solution (0.1 N. Hei ). After filtration, it is diluted again in 250 mio to measure the disolved oxides. Eaeh element analysis should be done eomparing it with the standard solution. Another small quantity of samples filler (0.25 gr.) is disolved until dryed up in eoneentrated solution of hydrofluorie aeid (HF) + hydrogen perclorie aeid (HCI 04). After the evaporation of acids, 0.1 N hy­droehlorie aeid is added . It is then neeessary to wait for two hours before dilu­ting it again by adding distilled water in the bottle until the 500ml levei, to me­asure the total eontent in oxides. The results obtained from this analysis are given in the following tables.

5. CONClUSIONS

Historie mortars are composite materiais formed by a binder (or mixture of bin­ding medium) and a variety of inert materiais (mostly a mixture of inorganie eom­pounds, not always of erystaline nature) and some additives (sometimes of orga­nie nature) added in small quantities for the improvement of meehanieal strength of the mortar.

For our analysis, samples were not enough to give an accurate report and to draw a reliable eonclusion on it. Nevertheless, we would like to give here some very basie guidelines on our provisional eonclusions, whieh should be verified by further analysis.

The ehemieal results proved that estimation made for 1 M= 1 A, 2M=2A, 3M=3A is eorreet. 50 aeeording to the results obtained from ehemieal analysis, the compo­sition of our samples:

• 1 M and 1 A is a lime mortar with some puzzolanie additives and briek dust, whieh eontains approximately 40% lime in it.

• Also 3M and 3A are lime mortars eontaining puzzolanie additives and some briek dust, but slightly lower amount of lime and higher amount of puzzolanie additives and some briek dust from 1 M and 1 A.

• Whereas 2M and 2A is also lime mortar with some puzzolanie additives but do­es no't include any briek dust.

• 5ample with eode number 4 A has shown that it is also a lime mortar with a high quantity of lime; but the porosity test showed the lower pereentage of po­rosity, whieh is unusual for lime mortars. These irregularities have lead us not to include the results of this sample in our eonsideration.

From the optieal microscopy and from results of those done on insoluble parts of samples, it eould be seen that river sand, crushed green stone (gneiss) and crus­hed briek are used as aggregates for samples 1 M* and 3A *, and the aggregates for sample 2M* are river sand and erushed briek stone.

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From the gradation of these samples, it is noted that binder/aggregate ratio is: • (l,l;10)for1M* • (2;1) for 2M* • (1,1; 1) for 3A *.

The aggregate size distribution: • for 1 M* is from 15011 up to 2mm • for 2M* is from 15011 up to 4mm • for 3A * is from 15011 up to 2mm

In relation from the above data, and looking at the graph done to show size dis­tribution, 1 M* and slightly 3A * are richer in fines, whereas 2 M* have a higher proportion of bigger aggregates.

The salt analysis of the samples indicated that the percentage of salts which exis­ted in the samples are within the acceptable limits, except 2A which has a signi­ficant amount of nitrate and over limits chlorite. Also samples 4A and 1 M have an amount of salts over the limit.

As the JJbanierasJJ were covered with earth, this can be one reason for existing salts; it could also be due to products used for bath in an earlier period.

5.2. Proposals for repairing mortars

I relation with these banieras two main ideas can be followed: to repair them with only a new mortar or to use several compositions of new mortars related with existing ones', and thus obtaining better compatibil ity. We propose the second one, and so, we have four main compositions:

• a structural mortar (samples 3A and 3M) • binder: lime + pozzolana: 1, 2; 1 • aggregate: 1 (originated from river sand, crushed brick and green stone) • aggregate size: from O up to 2mm • binder: aggregate: 1.2; 1

• a white render mortar, for a 2 / 3 cms thick layer (samples 2A and 2M) • binder: lime + pozzolana (1 .5; 1) • aggregate: 1 (originated from river sand and crushed green stone ) • aggregate itself (3 part river sand and 2 part crushed green stone) • aggregate size: from O up to 4mm

• a pink render mortar, to be under white render mortar, for a 3 mms thick layer (samples 1 A and 1 M) • binder: lime + pozzolana (1.6; 0.4): 1 • aggregate: 1,1 • aggregate type: river sand 1 part, 0.6 river sand, 0.4 crushed green stone.

• a white coating, for a 0.5 / 1 mm thick layer (sample 5A) • binder: 3 lime • aggregate: 1 very fine marble dust.

[Sample 4 A has not being taken into consideration].

Ali these compositions should be used to make trial mixtures, with available ma­teriais, and then after new study and further analyses, choose the best compati­ble materiais.

6. REFERENCES

ADAM, J.P. La Construction Romaine: materiaux et techniques" Ed. Picard, Paris 1984. [ISBN 2 708401041

ADAM VELENI, P. The Ancient Agora of Thessaloniki: 5tratigraphy and small finds. in AE.M0 10 Thessaloniki 1997 (in Creek, with English summary)

COLLEPARDI, M. Degradation and restoration of masonry walls of historical buildings, in Mate­riais and Structures / Materiaux et Constructions. CAMBA 98 Document.

ERSEN, A.; KARACULER, M.; CULEC, A. Possible sustitutes for Khorasan mortar in Byzantine and Ottoman monuments , in International Colloquium. Methods for evaluating products for the ConseNation of porous building materiais in Monuments, Rome 19-21 June 1995.

MOUTSOPOULOS, N .C. Contribution a I ' Etude du plan de la vil/e de Thessalonique a I'Epoque romaine, in I'architecttura in Grecia, Atti dei XVI Congresso di Storia deU' Architecttura, Atene 1969, (Roma 1977)

PAPAYIANNI, I. A holistic way of studying mortars and bricks of ancient masonries for manufac­turing compatible repair materiais. CAMBA 98 Lecture.

VELENIS, C.: ADAM VELENI, P. Ancient Agora. Thessaloniki. Ed. University Studio Press A. E., Thessaloniki 1997 (in Creek, with English summary).

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