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

1. Innovations in concrete and
mortar materials
Kevin Paine
BRE Centre for Innovative Construction Materials

2. Research topics
Low carbon cements
Nanotechnology enhanced
cements
Self-healing mortars and
concrete

3. Low carbon cements

5. 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

6. 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

7. UK Environment Agency Policy on
Carbon Reduction in Concrete
Carbon cap of 250 kg.CO2/m3

8. Non-Portland cements
Calcium sulfoaluminate cements
Geopolymers and alkali-activated cements
Supersulfated cements
Lime-Pozzolans

9. 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

13. Embodied CO2 to achieve concrete strength of 33 MPa

15. Low Carbon Concretes
Lower
carbon footprints!!

16. NANOTECHNOLOGY MODIFIED CEMENTS
Sanchez et al. Construction and Building materials 24 (2010)

17. Nanosilica
Nanoclay

18. Nanosilica

19. Nanoclay

20. Dihydrogenatedtallowmethylammonium salt

21. 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.

24. Faster setting
Stronger
(early age and
long-term)
Less
permeable
Without adversely affecting constructability or sustainability

25. SELF-HEALING
CONCRETE

26. Concept

27. Options
Unhydrated cement
Epoxy resins and glues
Bacterial spores
Superabsorbent polymers
others

28. 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

29. Spore producing bacteria

30. Calcite precipitating bacteria

32. Preliminary work @Bath