ARISTOTLE UNIVERSITY OF THESSALONIKI

LAB. OF BUILDING MATERIALS

PROJECT: EC FORTMED

MONUMENT: CASTLE OF SERVIA

SUBJECT: TRIAL MIXES FOR THE SELECTION OF

NEW REPAIR MORTARS

COMPATIBLE TO THE OLD ONES

AIM

The aim of this phase of the project was :

To manufacture and test a series of compositions

of repair mortars, from which the most suitable

would be selected for the interventions so as

to be compatible with the existing structure and

be resistant to the environmental conditions.

STEPS FOLLOWED

A) Selection and testing of the available raw

materials

BINDERS

The binding agents used were :

Hydrated lime (powder)

Ground natural pozzolana from Milos

island (Retained on 45μm sieve 10%)

White Cement

Clay

Hydrated Lime

The hydrated lime (powder), available at the

market, was tested before its use. The

characteristics of it, are shown in the following

table

Content in Ca(OH)2 58,5 (%w.w.)

(measured by

DTA-TG)

Specific Gravity 2,014

Fineness See diagram

attached

Pozzolana

The natural pozzolana from island Milos was

used after grinding, so as its residue retained on

the 45μm sieve to be 10%.

The pozzolan was used to enhance the strength

development since the pure lime mortars

develop very slowly the strength which is

generally low 1.0 –1.5 MPa

The other characteristics are shown in the table

Chemical

composition

Soluble oxides

(%w.w)

K2O Na2O

2,43 1,46

Soluble salts Cl- NO3- SO4

--

0,04 0,02 0,07

Pozzolanicity

index(with lime)

(ASTM C 618-83)

Compressive strength: 4.5MPa

Specific gravity 2,220

Porosity (%)

of standard

mortar with lime (RILEM OPC 11.3)

18,87%

Clay

The fines (fragment < 250μm) of the sand of the

Aliakmon river, which is near the Servia Castles,

exhibit pozzolanic reactivity.

This was previously observed during the

evaluation of the river sand.

The characteristics of the clay are depicted in the

table.

Composition

K2O

Na2O

SiO2 (total soluble)

Al2O3

Fe2O3

Soluble salts

Cl-

NO3-

SO4--

1,43

1,71

67,6

12,4

5,52

0,00

0,00

0,02

Specific gravity : 2,496

Fineness: 90% passes 200μm

sieve

Organic Substances: no exist

(ASTM C 40-79)

Color (Munsell scale): HUE

2,5Y 8/2 pale yellow

Particle size analysis of clay used for the mortar mixtures

(Malvern Mastersizer 2000)

Particle Size Distribution

0.1 1 10 100 1000 3000

Particle Size (µm)

0

1

2

3

4

5

6

Volu

me (

%)

POZZOLANA, 19 Feb 2002 11:45:09

Particle Size Distribution

0.1 1 10 100 1000 3000

Particle Size (µm)

0

1

2

3

4

5

Volu

me (

%)

claydry2, 03 Jun 2002 10:40:16

Particle size analysis of lime dust used for the mortar mixtures

(Malvern Mastersizer 2000)

Particle size analysis of grained pozzolana used for the mortar mixtures

(Malvern Mastersizer 2000

White cement

This type of cement was selected because of its

color and low content in alkalis (<0,6%).

Water

Drinking water was used for the mixing. Its

content of soluble salts was:

Soluble salts (% w.w.)

Cl- : 0,06

NO3- : 0,00

SO4-- : 0,02

Special care was taken in order the mixtures

to have low content in soluble salts to avoid

efflorescence as much as possible.

Admixtures

A superplasticizer, free of sulfates, based on

polycarboxylic compounds was used in low

percentage (1% by weight of binders), in order to:

increase the plasticity of the mixture

and reduce the water requirement of the mortar

mixtures.

Air entrancing agent was used in very small

quantity 0,01-0,02% w/w, of the binder in order:

• to increase the resistance of these lime-based

mortars to freezing- thawing cycles.

Aggregates

• The aggregates used were of the same origin with

those of the old mortars. They came from the near

the castles river Aliakmon, and are mainly silicious

and of dark color.

• The binder/aggregate ratios found in the old

mortars were kept as well the gradation found by

sieve analysis.

The characteristics of aggregates are given in

the table below and the gradation of them is given in

fig.1, in comparison with a characteristic gradation

of one of the old mortars.

Soluble salts

Specific

gravity

Cl- NO3- SO4

--

Sand

0-2mm2,65 0,00 0,00 0,01

Sand

2-6mm2,65 0,01 0,00 0,03

Gravel

6-20mm2,64 0,01 0,00 0,02

0.01 0.10 1.00 10.00 100.00

0.00

20.00

40.00

60.00

80.00

100.00

0.00

20.00

40.00

60.00

80.00

100.00

0.00

2.00

4.00

6.00

8.00

10.00

0.00

20.00

40.00

60.00

80.00

100.00

------: Mortar No 83

------: New composition

Figure1: Granulometric curve of aggregates – old mortar

B) The preparation of mortar mixtures

Three series of synthesis were prepared:

A: with binder/aggregate 1:2

binding agents: lime-pozzolana 1:1 (A1),

lime-pozzolana-white cement 1:0.8:0.2 (A2)

lime-pozzolana-white cement 1:0.6:0.4 (A3)

B. with binder/ aggregates 1:3

binding agents: lime-pozzolana 1:1 (B4),

lime-pozzolana-white cement 1:0.8:0.2 (B5)

lime-pozzolana-white cement 1:0.6:0.4 (B6)

C. with binder/aggregates 1:3

binding agents:

lime – pozzolana –clay 1:0.6:0.4 (C7)

lime-pozzolana-white cement-clay 1:0.4:0.2:0.4 (C8)

lime-pozzolana-white cement-clay 1:0.2:0.4:0.4 (C9)

These three main series were repeated by using

superplastisizer and air-entraining agents.

Therefore, the synthesis

AS10, AS11, AS12 / BS13, BS14, BS15 / CS16,

CS17, CS18, as well as the

AE19, AE20, AE21 / BE22, BE22, BE23 /

CE24, CE25, CE26,

were also produced to check the effectiveness of

admixtures.

The proportion of the mixtures, are shown in the

diagrams, while in the tables, some additional

parameters are given (see APPENDIX).

A total number of 243 specimens

(4x4x16 cm), was cast for the needs of different

tests, which have to be applied.

Plasticity was also measured by using

flow table, according to DIN 81555

COMPOSITION No A1

Lime

Pozzolan

Sand (0-2mm)

Sand(0-4mm)

Grav el (4-20mm)

Water

Lime

Pozzolan

Sand (0-2mm)

Sand(0-4mm)

Gravel (4-20mm)

Water

COMPOSITION No B4Lime

Pozzolan

Sand (0-2mm)

Sand(0-4mm)

Gravel (4-20mm)

Water

Lime

Pozzolan

Sand (0-2mm)

Sand(0-4mm)

Gravel (4-20mm)

Water

COMPOSITION No C7

Lime

Pozzolan

Sand (0-2mm)

Sand(0-4mm)

Gravel (4-20mm)

Water

Clay

Lime

Pozzolan

Sand (0-2mm)

Sand(0-4mm)

Gravel (4-20mm)

Water

Clay

Graphics 1-3: Proportions of weight

TESTS

The specimens of all mixtures were subjected to the

measurement of:

• Flectural – Compressive strength,

at 14-d 28-d age, (ASTM C 19-81)

• Modulus of Elasticity,

at 14-d 28-d age, by using ultrasonic pulse velocity,

(ASTM C 597-71)

• Porosity

at 28-d age, (RILEM CPC 11.3)

• Capillary Suction

at the age of 28 days, (NORMAL 11/85)

• Shrinkage deformation

at 14-day age, (ASTM C 157-80)

CORROSION TESTS

(according to RILEM recommendations)

28 days after the manufacture of the repair

mortars, some corrosion tests took place.

• Influence of humidity

• Influence of salts (Na2SO4 10% w.w.)

• Influence of frost

RESULTS

The results of all these tests are given below, in the

form of tables and graphics.

Analytically, the measurements are included in the

appendix.