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