1. ASSESSMENT OF THE E-MODULUS OF RECYCLING CONCRETE WITH DIFFERENT REPLACEMENT RATE
Luc BOEHME , Miquel JOSEPH
KU Leuven – Faculty of Engineering Technology - Department of Civil Engineering, Ostend, Belgium –

2. content Sustainable material cycles: let’s recycle CDW
Recycling - yes, we can !
A closer look at the E-modulus
Observations & conclusions

3. KU Leuven – Faculty of Engineering Technology Department of Civil Engineering
Technology Cluster Construction
Technology Campus De Nayer
Materials & Structures
Technology Campus Ostend
Coastal & Geotechnical Engineering
RecyCon
De Technologiecluster Bouw groepeert het onderzoek op drie technologiecampussen in Oostende, Gent en De Nayer. Deze technologiecampussen stemmen overeen met de voormalige hogescholen met de opleiding Industrieel Ingenieur die sinds 2013 geïntegreerd zijn in de nieuwe faculteit Industriële Ingenieurswetenschappen van KU Leuven. Qua onderzoek valt dit onder het departement Burgerlijke Bouwkunde en in de meeste gevallen is er ook een goede samenwerking met de afdelingen van het departement zoals die net aan bod gekomen zijn.
De volgende slides geven per onderzoeksgroep een overzicht van de betrokken onderzoekers, de onderzoekstopics, de infrastructuur en het netwerk.
Technology Campus Ghent
Sustainable Buildings
Structural Mechanics & Building Materials
Geomatics

4. Sustainable material cycles: let’s recycle CDW
Waste problem
Construction sector : 25% waste generation
Landfilling of C&DW = banned !
Depletion of Raw Materials
Construction sector uses 40 to 50 % of all resources
Depletion of Raw materials:
Restrictions on excavation of
new clay !
sand & gravel from riverbed & seabed

5. Let’s recycle CDW Landfilling of C&DW (inert waste) = banned
Taxes imposed on landfilling: > 150 €/ t
C&DW  285 recycling centres in Flanders  95% recycling
gate depends on content / composition  (-3 €) +3 to +8 €/ t
C&DW:
14 x 106 t/y
(mixed) recycled aggregate 0/32 – 0/40
Coarse recycled concrete aggregate (RCA) 4/20 - 8/20
Fine fraction 0/4 – 0/8
RCA: 12 €/t v/s natural aggregates 18 €/t
No quarries  75% import for construction sector
Cost of imported aggregates increases due to price of petrol (transportation distance is large!!!)( + more CO2-emissions)
Transportation distance for C&DW is short

6. Recycling – yes, we can!  better: Selective demolition
Total demolition  bad quality RCA
 better: Selective demolition

7. Recycling – yes, we can !

8. Recycling – yes, we can ! State of the art processing =
Crushing – sieving – separation of contaminations / multiple steps

9. Recycling – yes, we can ! Since 2012 in Belgium: Standards changed
NBN EN 12620: aggregates for concrete  RCA
NBN EN 206-1: specifications for concrete
BENOR-certification: TRA550
20% RCA in products (concrete blocks, ,,,)
use in concrete C25/30
For indoor applications in structural elements

10. Recycling – yes, we can ! Use in structural elements
Mechanical properties
Compressive strength
Flexural strength
Static E-modulus
Influence of RCA material properties
On properties of fresh concrete (workability)
On properties of hardened concrete (compressive strength)
with proper mix-design the requirements for strength-class can be reached

11. Recycling – yes, we can ! More difficult to reach: E-modulus
Influenced by
Nature of the aggregates
Pores ( W/C , RCA, mixing, …)
Amount of mortar paste (recycling = new + old mortar)
Concrete quality ( compressive strength Cxx/yy )
Parameters needed for design structural elements
Compressive strength  can be reached in production
Static E-modulus  ??? Rule of thumbs
How can we estimate E-modulus ?

12. Recycling – yes, we can ! How can we estimate the static E-modulus
 in relation to the influencing parameters
W/C-ratio WA24 RCA WA equivalent
Compressive strength %RCA, W/C
Density pores W/C, WA24 RCA, %RCA
Research  narrowing down to values for practical use
W/C: 0,45 – 0,50 – 0,55
%RCA: 0 (ref) – 25 – 50
Strength class C25/30

13. Estat-modulus of RC
methodology
Limestone RCA

14. Estat-modulus of RC Typical composition of recycling concrete mixture
25% RCA and W/C=0,45
RCA 25-45
amount
density
volume
mass
moisture
absorption
1m³ mix
component
[kg/m³]
[L]
[kg]
[%]
CEMI 42,5
300 kg
3100
96,8
300
W/C = 0,45
135 L
1000
135
119,52
air
1,50 15
sand 0-4mm
29,88
2630
225,1
592
3,32
0,52
611,57
limestone 4-8mm
10,14
2650
76,4
202
2,04
1,07
206,53
limestone 6-20mm
45,37
2660
341,7
909
1,27
1,16
920,57
RCA 8-20mm
14,60
2730
110
4,66
6,01
314,21
Sum Concrete
1m³
2438
2472,39

15. Estat-modulus of RC v/s %RCA & WA equivalent
Similar trend & formulas

16. Estat-modulus v/s density  W/C & %RCA

17. Estat-modulus v/s Compression strength

18. Estat-modulus of RC – different authors

19. Estat-modulus of RC - Conclusion
Estat-modulus v/s
Replacement rate %RCA & W/C –ratio
Equivalent water absorption & W/C-ratio
Density of RC
Density & compressive strength
Overestimating E-stat  under-dimensioning structural elements
Underestimating E-stat  over-dimensioning structural elements
50% RCA  compressive strength: - 16% & E-stat : - 12%

20. Special thanks to the lab-technicians Zeger Sierens & Martijn Vandecasteele

21. references

22. Thank you for your attention !
Nieuwe tendensen in de wereld van de betontechnologie - Recyclage beton
Thank you for your attention !
Contact:
Luc Boehme
Program Director Construction Campus Ostend
Head of Research Group RecyCon
KU LEUVEN – Technology Campus Ostend
Zeedijk Oostende
Tel:
iiw.kuleuven.be/onderzoek/recycon