EXPERIMENTAL STUDY OF FLY ASH - BASED GEOPOLYMER CONCRETE : STRUCTURAL APPLICATIONS Linda Monfardini, PhD Student [email protected]UNIVERSITY OF BRESCIA Department of Civil Engineering, Architecture, Environment, Land Planning and of Mathematics PhD Course in: CIVIL AND ENVIRONMENTAL ENGINEERING
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EXPERIMENTAL STUDY OF FLY ASH- BASED GEOPOLYMER CONCRETE… · Alakaline Solution/Fly ash=0.35 Liquid/Fly Ash = 0.44 Compressive Strenght [MPa] Mixing Time Compressive Strenght [MPa]
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EXPERIMENTAL STUDY OF FLY ASH-BASED GEOPOLYMER CONCRETE:
J.Davidovits, High-alkali cements for 21st century concretes, in "Concrete technology, past present and future", Proceedings of V. Mohan Malhotra symposium, Ed. P. Kumar Metha, ACI SP-144, 1994, pp. 383-397.
Structural applicationsSi:Al = 2
LOI:It should be less than
5%Inhibition of reaction
Low contentof CaOAvoid fast
settingJ. Davidovits, M. Izquierdo, X. Querol, D. Antennucci, H.
Nugteren, V. Butselaar-Orthlieb, C. Fernández-Pereira, Y.
Luna, The European Research Project GEOASH:
geopolymer cement based on European coal fly ashes,
Technical Paper #22, Geopolymer Institute Library,
www.geopolymer.org, 2014.
EXPERIMENTAL STUDY OF FLY ASH-BASED GEOPOLYMERCONCRETE: STRUCTURAL APPLICATIONS
10/25Saint QuentinJuly 6-8,2015 Linda Monfardini - [email protected]
Rest period Curing time (60°C)
Extra water content27 26 27
8
0
5
10
15
20
25
30
GC27 (23kg/m3)
GC28 (25kg/m3)
GC30 (30kg/m3)
GC26 (80kg/m3)
Res
isten
za a
com
pres
sione
Rcm
2729
0
5
10
15
20
25
30
35
40
Curing 24 h Curing 48 h
Res
isten
za a
com
pres
sione
Rcm
27
35
0
5
10
15
20
25
30
35
40
Rest period 24 h Rest period 48 h
Res
isten
za a
com
pres
sione
Rcm
22
25
26 26
15
18
21
24
27
30
3 4 5 6 7 8 9 10 11
Res
isten
za a
com
pres
sione
Rcm
Tempo di miscelazione [Minuti]
Materials [kg/m3]
Coarse Aggregate (6-10 mm) 1201
Sand 647
Tot. Aggregates 1848
Class F Fly Ash 408
Sodium Hydroxide 8 M 41
Sodium Silicate 103
Extra H2O 35
Total 2435
Aggregates: 80% by mass
Coarse Aggregate/Sand = 2
Silicate/ Hydroxide= 2.5
Alakaline Solution/Fly ash=0.35
Liquid/Fly Ash = 0.44
Mixing Time
Com
pres
sive
Str
engh
t [M
Pa]
Com
pres
sive
Str
engh
t [M
Pa]
Com
pres
sive
Str
engh
t [M
Pa]
Com
pres
sive
Str
engh
t [M
Pa]
25-35 kg/m3
MIX DESIGN & CURING PARAMETRES
EXPERIMENTAL STUDY OF FLY ASH-BASED GEOPOLYMERCONCRETE: STRUCTURAL APPLICATIONS
11/25Saint QuentinJuly 6-8,2015 Linda Monfardini - [email protected]
39 (5656) 40 (5801) 41 (5946) 40 (5801)43 (6236)
42 (6091) 43 (6236)45 (6526)
8 (1160)
14 (2030)
20 (2900)
0
1000
2000
3000
4000
5000
6000
7000
0
5
10
15
20
25
30
35
40
45
50
0 7 14 21 28 35
Com
pres
sive
cub
ic st
reng
ht [p
si]
Com
pres
sive
cub
ic st
reng
ht [M
Pa]
Time [days]
GC1, HCGC2, HCGC2, AC
fcm=0.83 Rcm
Cylinder compressive strength:
33-37 MPa
HC:Heat CuringAC: Ambient Curing
STEP 2: MATERIAL CHARACTERIZATIONCUBIC COMPRESSIVE STRENGHT
3 Days: End of Curing
EXPERIMENTAL STUDY OF FLY ASH-BASED GEOPOLYMERCONCRETE: STRUCTURAL APPLICATIONS
12/25Saint QuentinJuly 6-8,2015 Linda Monfardini - [email protected]
STEP 2: MATERIAL CHARACTERIZATIONYOUNG’S MODULUS
UNI 6556BEAM 1
GC1BEAM 2
GC2
24 GPa 25 GPa
3.0
1022000
cm
cmfE
For ordinary concrete, Eurocode 2 recommends the following relation:
EXPERIMENTAL RESULTS
ANALYTICAL RESULTS
Ecm = 31- 32.5 GPaMaximum Aggregate size = 10 mm
EXPERIMENTAL STUDY OF FLY ASH-BASED GEOPOLYMERCONCRETE: STRUCTURAL APPLICATIONS
13/25Saint QuentinJuly 6-8,2015 Linda Monfardini - [email protected]
ANALYTICAL FORMULAS
UNI 6556
STEP 2: STRESS-STRAIN RELATIONSHIP
THORENFELDT et al.
EUROCODE 2
Test run in stroke control
EXPERIMENTAL STUDY OF FLY ASH-BASED GEOPOLYMERCONCRETE: STRUCTURAL APPLICATIONS
14/25Saint QuentinJuly 6-8,2015 Linda Monfardini - [email protected]
GC1-#1
GC1-#2
GC1-#3
GC1-#4
0
1000
2000
3000
4000
5000
0
5
10
15
20
25
30
35
0 2 4 6 8 10 12 14 16
Stre
ss σ
[psi]
Stre
ss σ
[MPa
]
Strain ε [‰]
Thorenfeldt et al.Eurocode 2Mean Curve
fcm = 29 MPa [4206 psi]εcm = 2.24 ‰
Ductile behavior in the post-peak phase
STEP 2: STRESS-STRAIN RELATIONSHIP
EXPERIMENTAL STUDY OF FLY ASH-BASED GEOPOLYMERCONCRETE: STRUCTURAL APPLICATIONS
15/25Saint QuentinJuly 6-8,2015 Linda Monfardini - [email protected]
• CMOD (Crack Mouth Opening Displacement)
• 2 CTOD (Crack Tip Opening Displacement)
• 2 MPD (Mid Point Displacement)
UNI EN 14651
STEP 2: MODULUS OF RUPTURE (MOR)
Goal:
Indirect analysis of tensile strenght
MODULUS OF RUUTURE
EXPERIMENTAL STUDY OF FLY ASH-BASED GEOPOLYMERCONCRETE: STRUCTURAL APPLICATIONS
16/25Saint QuentinJuly 6-8,2015 Linda Monfardini - [email protected]
0.00 0.01 0.02 0.03 0.04 0.05
0
100
200
300
400
500
0
1
2
3
4
0.0 0.3 0.6 0.9 1.2 1.5
CMOD [in]
Nom
inal
Str
ess σ
N[p
si]
Nom
inal
Str
ess σ
N[M
Pa]
CMOD [mm]
GC1OPC 40
Geopolymer Concreteσn= 3.3 MPaFL=10.6 kN
STEP 2: MODULUS OF ROPTURE
EXPERIMENTAL STUDY OF FLY ASH-BASED GEOPOLYMERCONCRETE: STRUCTURAL APPLICATIONS
17/25Saint QuentinJuly 6-8,2015 Linda Monfardini - [email protected]
STEP 3: FULL-SCALE TESTS
As = 4.02 cm2 fsy = 545 MPa
A’s = 0 σst,max,es = 260 MPa
ρl = 0.77 %ρv = 0.67 % Ast = 0.50 cm2
Mu = 0.9·d·As·fsy=51 kNmPu = 2 Mu / a = 89 kN
StirrupsØ 8/7.5
Four point bending test
EXPERIMENTAL STUDY OF FLY ASH-BASED GEOPOLYMERCONCRETE: STRUCTURAL APPLICATIONS
18/25Saint QuentinJuly 6-8,2015 Linda Monfardini - [email protected]
CURING CHAMBER
EXPERIMENTAL STUDY OF FLY ASH-BASED GEOPOLYMERCONCRETE: STRUCTURAL APPLICATIONS
After a rest period of 48 hours Curing: 60° C for 24 hours
19/25Saint QuentinJuly 6-8,2015 Linda Monfardini - [email protected]
TEMPERATURE MONITORING
EXPERIMENTAL STUDY OF FLY ASH-BASED GEOPOLYMERCONCRETE: STRUCTURAL APPLICATIONS
20/25Saint QuentinJuly 6-8,2015 Linda Monfardini - [email protected]
COMPARISON OF RESULTS
Test Day:
31 days
Pu = 95 kN
δu = 156 mm
E = 24 GPa
Test Day:
8 days
Pu = 92 kN
δu = 127 mm
E = 25 GPa
Beam GC1
Beam GC2
EXPERIMENTAL STUDY OF FLY ASH-BASED GEOPOLYMERCONCRETE: STRUCTURAL APPLICATIONS
21/25Saint QuentinJuly 6-8,2015 Linda Monfardini - [email protected]
LOAD-DISPLACEMENT
0 1 2 3 4 5 6 7
0
5000
10000
15000
20000
0
10
20
30
40
50
60
70
80
90
100
0 50 100 150 200
Mis-span displacement [in]
Loa
d [lb
]
Loa
d [k
N]
Mid-span displacement [mm]
GC1GC2
Pu,GC1 = 95 kN
Pu,GC2 = 92 kN
δu,GC1 = 156 mm
δu,GC2 = 127 mm
Py,GC1 = 85 kN
Py,GC2 = 86 kN
δy,GC1 = 37 mm
δy,GC2 = 38 mm
Pu, predicted = 89 kN
Ductility: δu / δyGC1 = 4.16GC2= 3.26
EXPERIMENTAL STUDY OF FLY ASH-BASED GEOPOLYMERCONCRETE: STRUCTURAL APPLICATIONS
22/25Saint QuentinJuly 6-8,2015 Linda Monfardini - [email protected]
Beam GC1 Baem GC2
Experiental result
Srm = 113 mm
Experimental result
Srm = 102 mm
CRACK PATTERN
EXPERIMENTAL STUDY OF FLY ASH-BASED GEOPOLYMERCONCRETE: STRUCTURAL APPLICATIONS
23/25Saint QuentinJuly 6-8,2015 Linda Monfardini - [email protected]
EXPERIMENTAL STUDY OF FLY ASH-BASED GEOPOLYMERCONCRETE: STRUCTURAL APPLICATIONS
COLLAPSE
24/25Saint QuentinJuly 6-8,2015 Linda Monfardini - [email protected]
• Compression strength had a limited increase in time after the heat curing;• Experimental Young’s modulus is lower than ordinary concrete;• Constitutive law: in pre-peak phase, a trend similar to analytical formulas proposed
for ordinary concrete. In post-peak response GC presented a more ductile behavior;• MOR tests pointed out a rather brittle behavior coincident to ordinary concrete;• Despite difference in testing time, flexural behavior of full-scale beams did not
show differences in terms of ultimate load; on the contrary there are minordifference in terms of ultimate displacement and ductility;
• As expected for ordinary concrete, full-scale beams reached failure because ofconcrete crushing with yielded steel;
• Experimental mean crack spacing fits well with analytical formulas for ordinaryconcrete.
CONCLUSIONS
EXPERIMENTAL STUDY OF FLY ASH-BASED GEOPOLYMERCONCRETE: STRUCTURAL APPLICATIONS