Embed Size (px)
Citation preview
Korkean ilmamääränvaikutus betoninpuristuslujuuteen
L. Fülöp, M. Ferreira, E. Bohner, M. Leivo, M. Niemelä
Betonitutkimusseminaari 201930.10.2019
30.10.2019 VTT – beyond the obvious 1
Outline Background and aims of the EXACT project
Project structure
Results on mechanical properties (only few illustrative examples)
Results on durability properties (only few illustrative examples)
Concussions / Discussion
30.10.2019 VTT – beyond the obvious 2
Background to EXACT
30.10.2019 VTT – beyond the obvious 3
Concrete bridges cast with excessive amount of air entrainment (AE). The effects on mechanical and durability properties is not always well understood.
The 2018 “100 siltaa” project showed that there is no immediate safety concern due to AE.
Mita
ttu
ilmam
äärä
(ilm
a-ja
tiiv
isty
shuo
kose
t)
Poranäytteiden tutkimukset.Ilmamäärä vs. valuaika
y = 8E-06x - 0,2665R² = 0,2446
1.1.2003 27.9.2005 23.6.2008 20.3.2011 14.12.2013 9.9.2016
15
10
5
0
%
Valupäivä
Tässä tutkimuksessa asetettuohjeellinen yläraja, 7,5 %
Source: 100 siltaa - mitä opittiin, L. Salparanta, L. Fülöp, M. Ferreira, E. Bohner, M. Leivo, M. Niemelä, S. Kunttu, VTT Oy, Betonitutkimusseminaari 2018
25
35
45
55
65
75
85
35 37 39 41 43 45 47 49
VTT – beyond the obvious 5
85
75
65
55
45
35
25
Mita
ttu
ikäk
orja
ttu
luju
us, K
k/ 0
,85
35 37 39 41 43 45 47 49Suunniteltu lujuus K
Poranäytteiden tutkimukset. Ikäkorjattu
Livin tarkastelu
VTT – beyond the obvious
6 alitusta
Source: 100 siltaa - mitä opittiin, L. Salparanta, L. Fülöp, M. Ferreira, E. Bohner, M. Leivo, M. Niemelä, S. Kunttu, VTT Oy, Betonitutkimusseminaari 2018
Aims of the EXACT project
30.10.2019 VTT – beyond the obvious 6
However, it is not possible to confidently re-assess the integrity and durability of RC structures built with excessive AE.
The project EXACT “Performance of reinforced concrete structures with excess air entrainment “ aims to develop understanding of the properties and guide the re-assessment of AE bridges.
EXACT is financed by the Finnish Transport Infrastructure Agency.
Project structure
WP1 – Characterization of the basic mechanical properties
WP2 - Characterization of the basic durability properties
WP3 - Design and testing of structural elements
WP4 - Recommendations for re-assessing the concrete structures with AE
30.10.2019 VTT – beyond the obvious 7
Results on mechanical properties For mixes – 0%AE, 5%AE and 10%AE and 15%AE. Results:
• Static compression - strength EN 12390-3 and stress-strain curve (fcm, fck, fck,cube, Ecm, εc1, εcu1, εc2, εcu2) & strength development with age (7, 28, 91, 356 days)• Static tension - split test EN 12390-6 (fctm, fctk,0.05 and fctk,0.95)• Confined static compression and extension• Static shear over cracks (τs) Sorry no time... • Cyclic compression (fc & Ecm , degradation of strength and stiffness, cyclic energy)• Cyclic notched bending (bending tension fcbm, degradation & fracture energy)• Creep and shrinkage (ASTM C512/C512M-15) Sorry no time... • Reinforcement pull-out (Φ12 and Φ25) Sorry no time...
30.10.2019 VTT – beyond the obvious 8
Static compression (e.g. 0%AE, 28 days)
30.10.2019 VTT – beyond the obvious 9
εL
σ
εD
0
10
20
30
40
50
60
0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008
σ(N
/mm
2 )
εL(), contraction
0% AE Photo: L Fülöp, VTT Oy
y = 0.0898x - 165.38
y = 0.0999x - 180.46
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
2000 2050 2100 2150 2200 2250 2300 2350 2400 2450
com
pres
sion
str
engt
h (N
/mm
2)
Density (kg/m3)
fc (cylinder) fc (cubes)
Cylinder to cube constants. 1% extra AE ~3MPa strength
Splitting tensile (0%AE, 28 days)
30.10.2019 VTT – beyond the obvious 10
Splitting tensile strength calculated using the equation
𝑓𝑓𝑐𝑐𝑐𝑐 =2 � 𝐹𝐹𝑚𝑚𝑚𝑚𝑚𝑚𝜋𝜋 � 𝐿𝐿 � 𝑑𝑑
fctm decreases with the same slopeas predicted in Eurocode 2 (fctm=0.3*fck^(2/3)
y = 0.0049x - 8.0674
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
2050 2100 2150 2200 2250 2300 2350 2400 2450
Tens
ile st
reng
th (N
/mm
2)
Density (kg/m3)
Cyclic compression (0%AE, 28 days)
30.10.2019 VTT – beyond the obvious 11
σ
εL
0
10
20
30
40
50
60
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
Stre
ss (N
/mm
2 )
ec (%)
0C60C70C8
εD
Photo: Veli-Matti Hakala, Aalto ENG
Confined test (0%AE, 28 days)
30.10.2019 VTT – beyond the obvious 12Photos: P. Eloranta, Aalto ENG
σ
εL
εD
Notched bending tensile (0%AE, 28 days)
30.10.2019 VTT – beyond the obvious 13Photos: Ari Lehtonen, Eurofins Oy
CMOD
Force
Results on durability properties For EA mixes – 0%AE, 5%AE and 10%AE and 15%AE. Results:
• Freeze-thaw testing – scaling: CEN/TS 12390-9 with NaCl solution on surface (wtSC, RDMFF and RDMUPTT)• Freeze-thaw testing – internal damage: CEN/TR 15177 with water solution on surface (wtSC, RDMFF and RDMUPTT)• Chloride diffusion: CEN/TS 12390-11 (chloride diffusion coefficient)• Chloride migration: prEN 12390-18 (chloride migration coefficient)• Electrical resistivity : RILEM TC-154 technical recommendation (ER) Sorry no time... • Ultrasonic pulse velocity: VTT internal procedure (UPV) Sorry no time... • Carbonation – accelerated testing: SFS-EN 13295 (kCA) Sorry no result yet... • Carbonation – natural testing: VTT internal procedure (kCN) Sorry no result yet... • Capillary absorption: VTT- 385-86 (p, wt, kABS) Sorry no result yet...
30.10.2019 VTT – beyond the obvious 14
30.10.2019 15
Results on durability properties - Thin section analysis
0A37 5B71
10B86 15A42
VTT – beyond the obvious
30.10.2019 VTT – beyond the obvious 16
Freeze-thaw resistance0B99
15B79
30.10.2019 VTT – beyond the obvious 17
Chloride ingress – Diffusion vs Migration
Mixes 0 % 5 % 10 % 15 %Average 10.9 9.3 10.2 11.5Cov (%) 5.7 6.7 17.5 3.9
Detailed results (becoming public soon)..
“M. Niemelä, L. Fülöp, Excessively air entrained concrete –Characterization of the basic mechanical properties, VTT Technical Research Centre of Finland Oy, VTT-R-06996-18”
“M. Ferreira, L. Fülöp, Excessively air entrained concrete –Characterization of the basic durability properties, VTT Technical Research Centre of Finland Oy, VTT-CR-00988-19”
30.10.2019 VTT – beyond the obvious 18
DiscussionMechanical properties are adversely affected by the AE.
Uniaxial compression is one of the most affected ones. This is good, because uniaxial compression is benchmark test.
Creep is increased (~doubled at 40% load). In applications, the high % AE concrete is exposed to proportionally more load!
30.10.2019 VTT – beyond the obvious 19
Discussion Freeze-thaw durability is not compromised with access AE,
when air characteristics are good.
Chloride ingress by diffusion increases with increasing amounts of AE. When measured using migration test no difference was detected.
Planning of component scale test is ongoing.
30.10.2019 VTT – beyond the obvious 20
KIITOS!
30.10.2019 VTT – beyond the obvious 21
