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 – luc.boehme@kuleuven.be

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

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

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

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 fee @the 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

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

Recycling – yes, we can !

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

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

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

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 ?

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

Estat-modulus of RC methodology Limestone RCA

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

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

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

Estat-modulus v/s Compression strength

Estat-modulus of RC – different authors

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%

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

references

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 101 - 8400 Oostende Tel: +32 50 405945 luc.boehme@kuleuven.be iiw.kuleuven.be/onderzoek/recycon