01 Low Carbon South West january LCBB Uni of Bath kevin paine 21jan14
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Transcript of 01 Low Carbon South West january LCBB Uni of Bath kevin paine 21jan14
Kevin Paine
BRE Centre for Innovative Construction Materials
Innovations in concrete and
mortar materials
Research topics
Low carbon cements
Nanotechnology enhanced cements
Self-healing mortars and concrete
Low carbon cements
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
Common cements
Cem en t /
com bin at ion
d esign at ion
Nam e Secon d ary m ain
con st ituen t or ad d it ion
(Lo w – h igh con ten t , %)
Em bo d ied CO 2
Kg CO 2/ t on n e
CEM I Port lan d cem en t 930
II/A-LL or L Port lan d lim eston e
cem en t
6 – 20 lim eston e 880 - 750
II/A-V
Port lan d fly ash cem en t
6 – 20 fly ash 870 - 750
II/B-V 21 – 35 fly ash 730 - 610
III/A
Blastfu rn ace cem en t
36 – 65 ggbs 610 - 360
III/B 66 – 80 ggbs 340 - 230
IV/B-V Siliceous fly ash cem en t 36 – 65 fly ash 590 - 420
UK Environment Agency Policy on
Carbon Reduction in Concrete
Carbon cap of 250 kg.CO2/m3
Non-Portland cements
Calcium sulfoaluminate cements
Geopolymers and alkali-activated cements
Supersulfated cements
Lime-Pozzolans
Lime-Pozzolans
Potential embodied CO2
of lime-pozzolans
250 kgCO2/t
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.
Embodied CO2 to achieve concrete strength of 33 MPa
Low Carbon Concretes
Lower
carbon footprints!!
Sanchez et al. Construction and Building materials 24 (2010)
NANOTECHNOLOGY MODIFIED CEMENTS
Nanosilica Nanoclay
Nanosilica
Nanoclay
Dihydrogenatedtallowmethylammonium salt
How they work
Seeding of hydration reactions (nuclei for
cement phases)
Promote cement
hydration due to their high
reactivity
Act as fillers densifying the microstructure
Highly reactive pozzolans.
Faster setting Stronger
(early age and long-term)
Less permeable
Without adversely affecting constructability or sustainability
SELF-HEALING
CONCRETE
Concept
Options
Unhydrated cement
Epoxy resins and glues
Bacterial spores
Superabsorbent polymers
others
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
Spore producing bacteria
Calcite precipitating bacteria
Preliminary work @Bath