Sustainable Cements and Sustainable Cements and Concretes for the - - PowerPoint PPT Presentation

Sustainable Cements and Sustainable Cements and Concretes for the Future Concretes for the Future

Jay Sanjayan Professor of Concrete Structures Centre for Sustainable Infrastructure Swinburne University of Technology Swinburne University of Technology

Global Materials Consumption p

22.4 Concrete 6.8 l Coal 3.8 Oil

. .

1.5 Steel 0.3 Plastic

5 10 15 20 25

Billion Tons / Year

Sustainability?

CO2 Emissions Breakdown

0 4000 0.3500 0.4000 0 2500 0.3000

3

0.2000 0.2500 CO2-e/m3 0.1000 0.1500 t C 0.0500 0.1000 0.0000 25MPa 32MPa 40MPa 50MPa GP Cement Coarse Aggregates Fine Aggregates GP Cement Coarse Aggregates Fine Aggregates Concrete Batching Construction Activities Concrete Transport

CO2 Emissions Breakdown

0 3500 0.3000 0.3500 0 2000 0.2500 m3 0.1500 0.2000 t CO2-e/m 0.1000 t 0.0000 0.0500 25MPa (FA) 32MPa (FA) 25MPa (GGBFS) 32MPa (GGBFS) 25MPa (GP) 32MPa (GP) GP Cement Fly Ash GGBFS GP Cement Fly Ash GGBFS Coarse Aggregates Fine Aggregates Concrete Batching Construction Activities Concrete Transport

Cements without Portland cements Cements without Portland cements

• Geopolymer / alkaline activated cements
• Supersulfated cements

Supersulfated cements

• Calcium aluminate cements (CAC)
• Calcium sulfoaluminate cements (CSA)
• Magnesium oxy‐carbonate cements (MgO)

Magnesium oxy carbonate cements (MgO)

Research in Geopolymer and/or Alkali A ti t d C t Activated Cements

150 s 100 blications 50 earch Pub 50 Rese 1990 1995 2000 2005 2010 Year

Geopolymer Geopolymer

• Alumino silicate source

– metakaolin – fly ash slag – slag

+

• Alkaline activators

sodium hydroxide – sodium hydroxide – sodium silicate

No large capital investments in cement manufacture

Tensile Strength Tensile Strength

Elastic Modulus Elastic Modulus

Poisson’s ratio

Fracture Energy Fracture Energy

Characteristic Length g

2 F ch

f E G l =

t

f

Sorptivity

Fire Resistance

Moisture Release in Concrete

Supersulfated cements Supersulfated cements

• Slag (70‐80%) + Calcium sulfate (10‐20%) +

Alkaline activator (<5%)

• Alkaline Activator = Portland cement (<5%)
• Alkaline Activator = Portland cement (<5%)
• Slags, ideally >14% Al2O3
• French standard: NF EN 15743:2010
• High sulphate resistance
• High sulphate resistance

Biogas Tank

Calcium aluminate cements (CAC) Calcium aluminate cements (CAC)

• High Alumina Cement
• Conversion:

Conversion:

– Metastable hydrates Stable hydrates

( )

• Expensive (uses bauxite)

Calcium sulfoaluminate cements (CSA) Calcium sulfoaluminate cements (CSA)

d d d di d i Chi f 30

• Used and standardized in China for 30 years
• Limestone + Bauxite + Gypsum
• Expensive
• Clinkering temperature is reduced by 200oC

Clinkering temperature is reduced by 200 C

• Expansive

shrinkage compensation – shrinkage compensation – self prestressing

L f d bi d P tl d t/CSA

• Lafarge produces combined Portland cement/CSA

– AetherTM (20‐30% less CO2)

Magnesium oxy carbonate cements Magnesium oxy‐carbonate cements

• Sorel cements
• Tec‐Eco cement

Tec Eco cement

• Novacem

What it means to Structural Engineers?

d i i l l i i l b d

• Concrete design is largely empirical, based on

200 years of experience, e.g.

– Reinforcement detailing – Crack widths, <0.1 mm self‐healing – Crack width design: 300 mm reo spacing – Long‐term creep and relaxation Long term creep and relaxation – Cover

• Empirical design is built on “standard”
• Empirical design is built on standard

Portland cement

Portland cement

• Very tightly standardised: eg AS 3972
• Very tightly standardised: eg.,AS 3972

Empiricism in Concrete Structural Design

Poisson’s ratio, ν =0.2 Thermal expansion = 10 με/oC Thermal expansion 10 με/ C

Empiricism in Concrete Structural Design

Does AS3600 permits the use of alternative concretes?

AS1379 – 2007, page 15

Conclusions

• The emergence of low carbon and alternative

bl cements are inevitable.

• We (concrete industry, structural designers,

e (co c ete dust y, st uctu a des g e s, specifiers, educators) should embrace the new cements by cements by

– knowledge and education – standards – caution