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01 Low Carbon South West january LCBB Uni of Bath kevin paine 21jan14

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Dr Kevin Paine explains the research that the University of Bath are conducting into sustainable concrete technology including lime-pozzolan and self healing concrete.

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01 Low Carbon South West january LCBB Uni of Bath kevin paine 21jan14

  1. 1. Innovations in concrete and mortar materials Kevin Paine BRE Centre for Innovative Construction Materials
  2. 2. Research topics Low carbon cements Nanotechnology enhanced cements Self-healing mortars and concrete
  3. 3. Low carbon cements
  4. 4. Opportunities to reduce eCO2 1. Using concrete selectively, after considering all options, and minimising the strength required 2. Using low carbon alternatives to Portland cement 3. Selecting precast concrete where appropriate 4. Using cladding effectively where required 5. Specifying locally sourced recycled aggregate 6. Minimising reinforcement steel through good design and detailing
  5. 5. Common cements C em en t / co m b in at io n d esign at io n Nam e Seco n d ary m ain co n st it uen t o r ad d it io n (Lo w – h igh co n t en t , % ) CEM I Portlan d cem en t II/ A-LL or L Portlan d cem en t Em b o d ied CO2 Kg C O 2 / t o n n e 930 6 – 20 lim eston e 880 - 750 6 – 20 fly ash 870 - 750 II/ B-V 21 – 35 fly ash 730 - 610 III/ A 36 – 65 ggbs 610 - 360 66 – 80 ggbs 340 - 230 36 – 65 fly ash 590 - 420 lim eston e II/ A-V Portlan d fly ash cem en t Blastfu rn ace cem en t III/ B IV/ B-V Siliceou s fly ash cem en t
  6. 6. UK Environment Agency Policy on Carbon Reduction in Concrete Carbon cap of 250 kg.CO2/m3
  7. 7. Non-Portland cements Calcium sulfoaluminate cements Geopolymers and alkali-activated cements Supersulfated cements Lime-Pozzolans
  8. 8. Lime-Pozzolans Lime-pozzolans are not a single material but a “new” binder technology. Future lime-pozzolan concretes may use different combinations of pozzolanic additions and aggregates to create optimised mix designs for specific applications. Potential embodied CO2 of lime-pozzolans 250 kgCO2/t
  9. 9. Embodied CO2 to achieve concrete strength of 33 MPa
  10. 10. Low Carbon Concretes Lower carbon footprints!!
  11. 11. NANOTECHNOLOGY MODIFIED CEMENTS Sanchez et al. Construction and Building materials 24 (2010)
  12. 12. Nanosilica Nanoclay
  13. 13. Nanosilica
  14. 14. Nanoclay
  15. 15. Dihydrogenatedtallowmethylammonium salt
  16. 16. How they work Seeding of hydration reactions (nuclei for cement phases) Act as fillers densifying the microstructure Promote cement hydration due to their high reactivity Highly reactive pozzolans.
  17. 17. Faster setting Stronger (early age and long-term) Less permeable Without adversely affecting constructability or sustainability
  18. 18. SELF-HEALING CONCRETE
  19. 19. Concept
  20. 20. Options Unhydrated cement Epoxy resins and glues Bacterial spores Superabsorbent polymers others
  21. 21. Proposed Bacteria-based Healing agent Spores from Alkali-resistant bacteria (bacillus?) Precursor e.g. calcium lactate (CaC6H10O6) Nutrients C, N and P CaC6H10O6 + 6O2 → CaCO3 + 5CO2 + 5H2O
  22. 22. Spore producing bacteria
  23. 23. Calcite precipitating bacteria
  24. 24. Preliminary work @Bath

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