An Investigation on the Alkali-Silica Reactivity of Đzmir...
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An Investigation on the Alkali-Silica Reactivity of Đzmir Region Aggregates Cement and Concrete Technology in the 2000 s Second International Symposium, 6-10 September, 2000. Istanbul, Turkey Halit Yazıcı Research Assistant Dokuz Eylül University, Department of Civil Engineering, Đzmir, Turkey Selçuk Türkel Assist. Prof. Dr. Dokuz Eylül University, Department of Civil Engineering, Đzmir, Turkey Bülent Baradan Prof. Dr. Dokuz Eylül University, Department of Civil Engineering, Đzmir, Turkey
Transcript of An Investigation on the Alkali-Silica Reactivity of Đzmir...
An Investigation on the Alkali-Silica
Reactivity of Đzmir Region Aggregates
Cement and Concrete Technology in the 2000 s
Second International Symposium, 6-10 September, 2000. Istanbul, Turkey
Halit YazıcıResearch Assistant
Dokuz Eylül University, Department of Civil Engineering, Đzmir, Turkey
Selçuk TürkelAssist. Prof. Dr.
Dokuz Eylül University, Department of Civil Engineering, Đzmir, Turkey
Bülent BaradanProf. Dr.
Dokuz Eylül University, Department of Civil Engineering, Đzmir, Turkey
ALKALI-SILICA REACTION IN CONCRETE
WITHIN TIME (∼ after 1 year)
ALKALI OXIDES FROM HIGH ALKALI
CONTENT CEMENTS
FORMATION of GEL (sodium + potassium +
calcium silicate)
VOLUME EXPANSION
CRACKING (MAP)
SILICEOUS CONSTITUENTS ( Opal, Calceduan,
Tridymite, etc. ) of SOME AGGREGATES
The mechanism of the alkali-silica reaction
Diffusion of water and alkalis into concrete
Water and/or alkalis from the environment (e..g. From de-
icing salts)
Crack formation (map cracking and surface
parallel cracking)
Diffusion of alkalis present in pore system (e.g. From cement
and admixtures)
Conversion of reactive
aggregate (formation of
gel); expansion
ReactiveAggregate
GEL FORMATION
The gel is usually transparent and resinous in appearance
Local pop-out: spalling or
micro-cracking due to ASR
GEL
CRACKING and SPALLING
ASTM C 227 Standard Test Method for Potential Alkali
Reactivity of Cement Aggregate Combinations (Conventional
long term- 6 Months)
CSA A23.2-25A Test Method for Detection of Alkali-
Silica Reactive Aggregate by Accelerated Expansion of
Mortar Bars (Canadian Method, Accelerated, 2 weeks)
ASTM C289 Standard Test Method for Potential
Reactivity of Aggregates (Chemical Method)
ASTM C295 Guide for Petrographic
Examination of Aggregates for Concrete
Not too
reliable
TEST METHODS FOR ALKALI-SILICA REACTION
Map-like cracking at abutment Buca Motorway Bridge in Đzmir
(Reported by Turkish General Directorate of Highways)
Alkali-Silica Reaction in Đzmir Region
EXPERIMENTAL PROGRAM
Test Methods
ASTM C227 (Conventional mortar bar test)
CSA A23.2-25A (Accelerated mortar bar test)
Materials
Aggregate: 5 different sand and non-reactive
reference aggregate (crushed limestone)
General Aim - To control the reliability of CSA Method
- To test sand samples procured from different quarries
Water: tap water
Cement: PC42.5
Alkali content: Na2O = 0.14 %, K2O= 1.12 %
Equivalent Sodium Oxide: (Na2O)e = Na2O + 0.658 K2O
(Na2O)e = 0.88 %
0.88 % > 0.6 % for ASTM
> 0.9 ± 0.1 for CSA
Measuring equipment
Specimens25x25x285 mm standard test prism
0
0,01
0,02
0,03
0,04
0,05
0,06
0,07
0,08
0,09
0,1
0 30 60 90 120 150 180
Time (days)
Avera
ge E
xp
an
sio
n (
%)
Çine
Gölmarmara
Turgutlu
Nazilli
Söke
Crushed limestone
Allowance limit
Expansion in Conventional Method (ASTM C227)
Expansion in Conventional Method (ASTM C227)
Allowance limit
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0 3 6 9 12 15
Time (days)
Av
era
ge
Ex
pa
ns
ion
(%
)
Çine
Gölmarmara
Turgutlu
Nazilli
Söke
Crushed limestone
Expansion in Accelerated Method (CSA)
Expansion in Conventional Method ( CSA A23.2-25A)
Relationship Between The Expansions Measured in the Accelerated and
Conventional Mortar Bar Tests
y = 0,7771x + 0,0121
R = 0,769
y = 0,9234x + 0,0471
R = 0,676
0
0,02
0,04
0,06
0,08
0,1
0,12
0 0,02 0,04 0,06
6 months mortar bar expansion in ASTM C227 (%)
14
da
ys
mo
rta
r b
ar
ex
pa
ns
ion
in
CS
A A
23
.2-2
5A
(%
)
without
thermal
expansion
with
thermal
expansion
Comparison the results of ASTM C227 and CSA A23.2-25A Methods
CONCLUSIONS
RATHER GOOD CORRELATION BETWEEN THE
CONVENTIONAL (ASTM) and ACCELERATED (CSA)
MORTAR BAR TEST RESULTS.
HIGHER EXPANSION VALUES ( ∼25 %) for CSA TEST
METHOD
NO POTENTIAL ASR RISK for ALL TESTED SAND
SAMPLES
An Investigation on the Alkali-Silica
Reactivity of Đzmir Region Aggregates
Cement and Concrete Technology in the 2000 s
Second International Symposium, 6-10 September, 2000. Istanbul, Turkey
Halit YazıcıResearch Assistant
Dokuz Eylül University, Department of Civil Engineering, Đzmir, Turkey
Selçuk TürkelAssist. Prof. Dr.
Dokuz Eylül University, Department of Civil Engineering, Đzmir, Turkey
Bülent BaradanProf. Dr.
Dokuz Eylül University, Department of Civil Engineering, Đzmir, Turkey
