This workshop is a deliverable of TRAC project which has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement Nº777823.
Presentation 2:
Utilization of Fine RCA together with MSWI Bottom Ashes
TANG Luping, Chalmers University of Technology, Sweden
Prof Tang received his PhD in 1996 at Chalmers University of Technology, Gothenburg, Sweden. Since then he has worked at SP Technical Research Institute of Sweden for 12 years and rejoined Chalmers since 2008 as professor and leader of research group for building materials. His main research interest is new types of cementitious materials and durability of concrete, especially chloride transport mechanisms and chloride induced corrosion of steel in concrete. In the past years he has been involved in several research projects dealing with greener cementitious materials including nano-technology and chemical activations.
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TRAC Project Workshop 2 Presentation 2
1. Acknowledgement:
This project that has received funding from the European Union’s Horizon 2020 Research and Innovation
Programme under grant agreement no. 777823
TRAC 2nd International Workshop, online, 30th Dec 2020
Grant reference: 777823
Project acronym: TRAC
Size of funds: €450,000
Period: 1st July 2018 to 30th June 2022
Utilization of Fine RCA together with MSWI
Bottom Ashes
LupingTANG, Liming Huang & Emma ZHANG (Chalmers)
4. Concrete Recycling
4
0.063 0.125 0.25 0.5 1 2 4 8 16 32 64
Particle size, mm
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
Chalmers Master’s thesis by Erik Johansson, 2011
Easier for reuse
Difficult for reuse
5. Ashes from Municipal Solid Waste Incineration (MSWI)
5
Source: Confederation of European Waste-Energy Plants, 2016
20% bottom ash per
incinerated waste!
6. Alkali-Activation Techniques
6
Using alkaline metal or alkaline
earth metal to activate the latent
hydration of minerals containing
silicon dioxide (SiO2) and
aluminum oxide (Al2O3) which
widely exist in the earth
as ”green” cementitious materials
7. Effect of Combined Additions for Shrinkage Control
7
Shrinkage (‰) = a1·Na2O% + a2 · SiO2% + a3 ·Gypsum% + b
-50
-40
-30
-20
-10
0
10
20
0 100 200 300 400
Drying duration, days
a1
a2
a3
SiO2
Na2O
Gypsum Expansion
Shrinkage
9. Laboratory Experiments
Swedish RCA from an old road bridge
• Coarse RCA (>4 mm) has been tested in another project
with reasonably good results
• Our focus is on the fine part of RCA (0-4 mm)
Average density about 2100 kg/m3
Water absorption about 9% by dry mass of RCA
11. Adsorption of Moisture by RCA Sand
• In general, fine particles adsorb more moisture
• Adsorption needs a long time to reach equilibrium
0%
1%
2%
3%
4%
5%
6%
7%
8%
9%
10%
< 0.075 0.075-0.125 0.125-0.25 0.25-0.5 0.5-1.0 1.0-2.0 2.0-4.0
Moisturecontentbymassofdrysample
Particle size, mm
6 days
16 days
32 days
63 days
262 days
12. 0 10 20 30 40 50 60
OPC-NS (Ref)
OPC-RFA0-4+2.5%w
OPC-RFA0-4+2.5%A
OPC-RFA0-4+3%A
CompressiveStrength [MPa]
(std curing)
7 days
28 days
Previous Results from Mortar Prisms
Almost just the effect of w/c ratio!
Eq. w/c 0.5
Eq. w/c 0.56
Eq. w/c 0.55
Eq. w/c 0.56
14. Bottom Ashes from Two Swedish MSWI Plants
14
Size Renova Fint 0-10 Stena Fint 0-10
0-0.5 mm 31.0% 23.3%
0.5-2 mm 39.3% 42.0%
2-10 mm 29.6% 34.7%
Moisture content
Renova Fint 0-10 15.32%
Stena Fint 0-10 14.40%
R-0-10 mm
S-0-10 mm
R-0-10 mm S-0-10 mm
R-0-10 mm
S-0-10 mm
16. Harmful elements in Bottom Ashes
16
0
2000
4000
6000
8000
10000
12000
14000
As Ba Be Cd Co Cr Cu Hg Mo Nb Ni Pb S Sc Sn Sr V W Y Zn Zr
[mg/kg]
Stena
S-0-05 S-05-2 S-2-10
0
2000
4000
6000
8000
10000
12000
14000
As Ba Be Cd Co Cr Cu Hg Mo Nb Ni Pb S Sc Sn Sr V W Y Zn Zr
[mg/kg]
Renova
R-0-05 R-05-2 R-2-10
R-0-10 mmS-0-10 mm
17. Hydraulic Activities (The Solution Test)
17
Mix 2 g sample with 40 g NaOH (1 M),
rotated (12 rpm) at 40 °C for 7 days
Stop hydration acc to RILEM
recommendation
Heat at 105 °C and 350 °C,
respectively
Determine the mass change between
18. Results from The Solution Test
18
0%
1%
2%
3%
4%
5%
R005 R052 R210 S005 S052 S210
Hydrates
(massdifferencebtween105-350°C)
Samples
Raw
1M NaOH
Low hydraulic activity in all sorts of ashes!
Finer ashes revealed a relatively higher hydrates, possibly due to the wet storage
19. Manufacturing Green Sands
19
Ratio of RCA(0-2mm) to bottom ash: 1:0.5
Alkali-activator (water glass based): 30-40% by mass of bottom ash
before gas release after gas releaseMixing in a drum under rotation
25. Concluding Remarks
Mixing RCA 0-4 mm with 2.5-3% alkali-activator can effectively keep the strength of AAS
mortar at the same level as using natural sand, but not for the OPC binder.
Pre-treating RCA 0-2 mm with ground MSWI bottom ash by means of alkali-activation
technique can
effectively overcome the problem of fine RCA in workability of concrete, and
replace natural sand by 70-100% without markedly imparing compressive strength.
Our preliminary experimental results show that