sustainable concrete construction more than co2 reduction...

Sustainable Concrete Construction –

more than CO2 reduction in cementPer Fidjestol

Elkem AS Silicon Materials

ScopeScope

• Sustainability discussions have a tendency to gravitate• Sustainability discussions have a tendency to gravitate towards CO2 release during cement and concrete production and means to reduce this.

• The concept of more sustainable construction obviously is• The concept of more sustainable construction obviously is more complex than this. E.g.• Raw material resources, • LCA and • LCCA.• Reduce embodied energygy• Reduce water use• Increase the use of recycled material• Reduce materials to landfill• Reduce materials to landfill• Reduce use of non-recycled material

21.11.20112

BasicBasic

S t i bilit• Sustainability concerns:• availability of materials, testing of alternate

s pplementar cementing materials bindersupplementary cementing materials, binder optimization and the minimization of concrete consumption as a means to save resources andconsumption as a means to save resources and minimize environmental impact.

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Raw MaterialsRaw Materials

C t d• Concrete needs:• Cement

A t• Aggregates• Addition and admixtures• Water• Water

• So what are the concerns?So what are the concerns?

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Cement - Availability of raw materialsCement Availability of raw materials

C l i d ili tl b d t!• Calcium and silica apparently abundant!

• Not so necessarily• Issues

• Quality• Location/transport• Environmental issues including landscape protection

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Consequences for cement productionConsequences for cement production

• As good original sources get exhausted transport• As good, original, sources get exhausted, transport gets into the picture• New sources can be diffucult to exploit – for location,New sources can be diffucult to exploit for location,

environment etc• Citizen pressures can force closure of plants• Ditto hinder new plants

• On a medium timescale, availability of raw materials, in particular limestone will be increasingly challenging

E I di h lf th h t d li t i t l• E.g. India: half the charted limestone reserves are in natural preserves

• Even in Scandinavia, limestone supply is becoming an issue

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AggregatesAggregates

• A pressing problem in many localities• A pressing problem in many localities• Key issue is natural aggregates (mainly sand)

• QualityQuality– Strength– Reactivity

E i t l• Environmental– Landscape protection– Particle pollution of water– Citizen’s protests– Example: RMC producer in Mumbai: Previously 2 km to go; now 130

km to go for sand

• Coarse aggregates less of a problem

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The CO2 challengeThe CO2 challenge

C t i h• Current main approach• Dilution of binder using mainly SCM’s and/or fillers

• How sustainable is that approach?

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NeedNeed

A h i ttit d t t t t d th i• A change in attitude to concrete structures and their design• Use high strength to minimize concrete volume• Use high strength to minimize concrete volume• Ensure flexible-use structures with long service life• Targets; Authorities owners and designers!Targets; Authorities, owners and designers!• Carrot and stick?

• For concrete materialsFor concrete materials• Develop use of manufactured sand• Develop alternate sources of large-volume SCMp g• Accelerate and focus development of binders with less CO2,

(geopolymers?)• Develop optimized mixes; ternary/quaternary etc

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Ensure flexible-use structures with long service lifeservice life

Ab l lit d h t i li• Abysmal quality and short service lives cause a significant part of present day demand for new concreteHPC ith ma im m ser ice li es can create lastingE l Chi• HPC with maximum service lives can create lasting structuresArchitects can design flexible building frames whose

Example: ChinaVisiting an Institute in Nanjing, 4 year old concrete building, through cracks in the stairwell outside wall• Architects can design flexible building frames whose

interiors can be upgraded with technological development

In Shenyang; at the University, a few year old structures: Outdoor columns cracked at corners, large wall panels had “beautiful” D-

kidevelopment

• There should be incentives for this

cracking

Statement by senior Chinese: Residential construction often has service life of only 5 10 years• There should be incentives for thislife of only 5-10 years

21.11.201110

Authorities owners and designers!Authorities, owners and designers!

C t d ti k?• Carrot and stick?• Premium for sustainable design – i.e.

High strength long service life– High strength, long service life

• Refuse building permits for other structures

• Or

• Fees depending on estimated service life

• Or

• ????21.11.201111

Develop use of manufactured sandDevelop use of manufactured sand

N t l d i i t• Natural sand is running out

• “Machine sand” is used today, but often cause huge challenges

• Equipment, procedures, guidance needed

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Develop alternate sources of large-volume SCMSCM

I• Issue• Germany has started investigations into “other” forms of low

CO2 cements; triggered by economic crisis in 2008CO2 cements; triggered by economic crisis in 2008– Energy need down – power plants closed – less fly ash

– Specified material could not be had– Demand for steel down – furnaces closed

– Specified slag cement unavailable

L ki i t th f t• Looking into the future:– Slag unavailable (production moved to Asia)– Less and less fly ash availableLess and less fly ash available

– Move to renewable energy sources– Detrimental production routines in power plants (Mercury etc)

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Alternative to by-product SCM’sAlternative to by product SCM s

W t lki + 15 h i• We are talking + 15 years horizon

• Totally different cement chemistries

• Natural pozzolans

• Ash from “other” processes

• ????????

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Particle size distributionsParticle size distributions9.00 Flyash class f, 11. april 2006

VC-ground

7.00

8.00 Metakaolin, GP procedure

EM 920D

Rice Husk USA, Primary agg method

Superpozz gulf p metode

5.00

6.00

Superpozz gulf p metode

4.00

2.00

3.00

0.00

1.00

Developing people -creating value

15

0.01 0.10 1.00 10.00 100.00

Natural pozzolansNatural pozzolans

C l i d ( d ill d)• Calcined (and milled)• Metakaolin

M l• Marl• ……..

• 4-500 kg CO2/ton

• Milled only• Santorini earthSantorini earth• Trass• Perlite

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MW-Perlite: TEM


17

Crystalline and amorphous phases intermixed on a nanoscale

Milled Perlite Typical particle size distribution (?)

St d dStandard progr.(30 sec. ultrasound,

25 % amplitude)

P i lPrimary aggl.(8 min. ultrasound, 100 % amplitude)


18

Chloride profiles – Perlite SCMChloride profiles Perlite SCM

0 9

1

0.8

0.9

White Cement Control

10% MW t A

0.6

0.7

%

10% MW type A

20% MW type A

10% MW type B

0.4

0.5

CL

% 20% MW type B

15% MW type A plus 5% silica fume

10% silica fume

0.2

0.310% silica fume

0

0.1


19

0 5 10 15 20 25mm

Diffusion coefficients, Perlite SCM

3E 113E-11

M2/sec

2.5E-11

3E-11

2.5E-11

1.5E-11

2E-11

2E-11

1E-11

1E 11

1.5E-11

0

5E-12

White CementControl

10% MW type A 20% MW type A 10% MW type B 20% MW type B 15% MW type Aplus 5% silica

10% silica fume5E-12

1E-11

Control plus 5% silicafume

0White 10% MW 20% MW 10% MW 20% MW 15% MW 10% silica


20

Cement Control

type A type A type B type B type A plus 5% silica

fume

fume

ASR: ASTM C1567 – Perlite SCMASR: ASTM C1567 Perlite SCM

0.50

0.40

0.45

%

100Cem

0.30

0.35

ansi

on, % 10 MW A

20 MW A

0.20

0.25

ge E

xpa

0.10

0.15

Ave

rag

0.00

0.05By Hooton


21

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28Time, days

Ash/waste from “other” processesAsh/waste from other processes

• Rice Husk Ash• Rice Husk Ash• Bagasse ash•• …….

• Municipal wasteMunicipal waste• Bioenergy power plants

• Ground waste glass• ……

• Documentation effort needed for all these

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Rice Husk Ash and Microsilica - StrengthRice Husk Ash and Microsilica Strength100

8080

60

MPa 100% PC

5% MS

40

10% MS5% RHA10% RHA10% RHA20% RHA

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200 10 20 30 40 50 60

ASTM C1202ASTM C12025000

Kontrollblanding

4000

450056 days

Kontrollblanding5% Silika10% Silika

3000

3500

b

20% Silika5% RHA10% RHA

2000

2500

oulo

mb

20% RHA

1000

1500C

0

500

1


24

Other SCM’sOther SCM s

A il bilit ?• Availability?• Flyash is available in huge

volumes comparable to clinkervolumes, comparable to clinker consumption

• RHA only maximum 5 mio tons• Natural pozzolans?

– Global reservesL i

1000 tonsPerlite, app 8 billion tons

– Location– Milling– Deposit volume

Greece 300 000

Turkey 5 700 000Deposit volumeUSA 200 000Other

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countries 1 500 000

Accelerate and focus development of binders with less CO2 (geopolymers?)binders with less CO2, (geopolymers?)

A l d l t d d t ti• A long development and documentation process• Technology• Stable quality• Long term performance

• General• Structural• Durability

• Until then……

21.11.201126

Sure steps to remove CO2:Sure steps to remove CO2:

• Minimize the amount of concrete using high strength

• Optimize mix design and use SCMOptimize mix design and use SCM• Use “any” means to remove superflous

concrete e g Bubbledeckconcrete, e.g. Bubbledeck

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Exercise done for local structure near University of Agder• Exercise done for local structure near University of Agder

45 Mpa SD 100 Mpa SD 45 Mpa BD 100 Mpa BD

Total cost [MNOK] 5.8 6.6 5.2 5.0Total CO emissions 532 354 380 242Total CO2 emissions [tonnes] 532 354 380 242Service life [yrs.](Life 365 default 53 206+ 53 206+ situation

SD: Standard beam/slab deckBD B bbl d k fl d kBD: Bubbledeck flat deck

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Short termShort term

U hi h t th ti i d (t ) i• Use high strength, optimized (ternary) mix• Saves raw materials

R d i i• Reduces emissions

• Long term/Urgent R&D needsAlt t SCM’• Alternate SCM’s

• Ensure fly ash useful• New binders with proven performance• New binders with proven performance

21.11.201130

sustainable concrete construction more than co2 reduction...

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