ARISTOTLE UNIVERSITY OF THESSALONIKI LAB. OF BUILDING...
Transcript of ARISTOTLE UNIVERSITY OF THESSALONIKI LAB. OF BUILDING...
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.