H d h bl f hi hHydrate phase assemblages for high performance low clinker cementsHydrate phase assemblages for low

clinker fit for purpose cementsDuncan Herfort

Cementir Holding

p p

Duncan HerfortCementir HoldinggCementir Holding

Introduction

H d h bl f hi h

Can we replace 50% clinker by a non-calcareous pozzolana (e.g. class F FA) for same concrete performance?

Hydrate phase assemblages for high performance low clinker cements

At first glance the answer is no, because the

• maximum replacement with a non-calcareous pozzolana for same

Duncan HerfortCementir Holding

p pstrength is c. 25%, and

• Except for N.America production of industrial SCMs falls well short of this in any event gy

Solutions to overcome this include developing

• natural pozzolana including calcined clays,• the synergy between limestone and alumino silicate pozzolana for

replacement up to 50%, andreplacement up to 50%, and• alkali activation for replacement higher than 50%

44

oduc

tion

improved kiln efficiency,biofuel,n.gas where practicable

Improved kiln efficiency, use of bio fuels & natural gas (0.93 109 t CO2)

3

cem

ent p

ro p

a

40% SMC for same concreteperformance

40% SCM for same concrete performance (0.88 109 t CO2)

2

issi

on fr

om

109 to

nne

1/3 of RM CO2 recarbonated

1/4 f CO2 i i t d

1/5 of RM CO2 recarbonated (0.34 109 t CO2)

2/5 of CO2 emissions captured

1

obal

CO 2

em

i 1/4 of CO2 emissions storedand captured

Serie1

and stored (0.83 109 t CO2)

Currently 25% is about the limit for non calcareous SCMs

02008 2050

Glo non calcareous SCMs

2008 2050

7580

a

606570

hs, M

Pa

45505560

stre

ngth

30354045

28d

s

300 10 20 30 40

clinker replacement, %clinker replacement, %

silica gelSiO2

20% Silica fume clays

C0 8SHy

pozzolans

0.8 y

C SH

70% GBFS35% basaltic pozzolan25% granitic pozzolan25% calcined clay or PFA

C-S-Hss

C1.7SHx 25% calcined clay or PFA

stratlingite

C3A.CS.H12

C3A.CC.H12

C3A.3CS.H32

CH

gibsite

C3APortland cement

g

CaO Al2O3

silica gel

Max clinker replacement by non calcareous pozzolana for equal concrete performance

20% Silica fume clays

concrete performancec. 25%

C0 8SHy

pozzolans

0.8 y

C SH

70% GBFS35% basaltic pozzolan25% granitic pozzolan25% calcined clay or PFA

C-S-Hss

C1.7SHx 25% calcined clay or PFA

stratlingite

C3A.CS.H12

C3A.CC.H12

C3A.3CS.H32

CH

gibsite

C3APortland cement

g

CaO Al2O3

silica gel

Max clinker replacement by non-calcareous pozzolans for equal concrete performance

20% Silica fume clays

c. 25%

Availability c. 10%

C0 8SHy

pozzolans

0.8 y

C SH

70% GBFS35% basaltic pozzolan25% granitic pozzolan25% calcined clay or PFA

C-S-Hss

C1.7SHx 25% calcined clay or PFA

stratlingite

C3A.CS.H12

C3A.CC.H12

C3A.3CS.H32

CH

gibsite

C3APortland cement

g

CaO Al2O3

World wide availability of Supplementary Cementitious Materials

Metakaolin

x

IEA production data

Silica fume

Rice husk ashIEA production data published 2008:

Cement 2500 tpa

Natural pozzolana

Burnt shale Used in cement

Reserve

Fly ash 300 tpa

BF slag 220 tpa

Blast furnace slag

Natural pozzolana

i.e. max 20% of cement

Cement

Fly ash

Limestone

0 100 200 300 400 500 600Mill. tons/year

World wide availability of Supplementary Cementitious Materials

Metakaolin

x

IEA production data

Silica fume

Rice husk ashIEA production data published 2008:

Cement 2500 tpaPotentially 25% for same concrete

Natural pozzolana

Burnt shale Used in cement

Reserve

Fly ash 300 tpa

BF slag 220 tpaperformance, but only 10% availability.Solution is to exploit existing

Blast furnace slag

Natural pozzolana

i.e. max 20% of cementSolution is to exploit existing landfilled PFA, natural pozzolana, or calcined clay

Cement

Fly ash

Limestone

or calcined clay

0 100 200 300 400 500 600Mill. tons/year

World wide availability of Supplementary Cementitious Materials

Metakaolin

x

IEA production data

Silica fume

Rice husk ashIEA production data published 2008:

Cement 2500 tpaThat still leaves us well short of

Natural pozzolana

Burnt shale Used in cement

Reserve

Fly ash 300 tpa

BF slag 220 tpaour target of 50% replacement

Blast furnace slag

Natural pozzolana

i.e. max 20% of cement

Cement

Fly ash

Limestone

0 100 200 300 400 500 600Mill. tons/year

7580

606570

hs, M

Pa

45505560

stre

ngth

354045

28d

300 10 20 30 40

clinker replacement %clinker replacement, %

The carboaluminate reaction suggests a way out.

7580

606570

hs, M

Pa

45505560

stre

ngth

354045

28d

300 10 20 30 40

clinker replacement %clinker replacement, %

CaSO4gypsum+ CSH + CH + FH+ CSH + CH + FH3+ pore solution

ettringite

monosulfate

thaumasite

Reduced porosity

Ms-ss

porosityIncreased porosity

C4AH13

calcite

MonocarbonateHemicarbonateC3A CaCO3

calcite

higher aluminate content = higher strengths

10

15nd

]

compressive strength measured

5

10

poro

sity

atre

ngth

[%]

increase

-5

0

chan

ge o

f pr

essi

ve s

t

decrease

15

-10

rela

tive

cco

m

total porosity calculated

-150 2 4 6 8 10 12 14 16 18 20 22

amount of CaCO3 added [wt.-%]

Very good correlation between predicted changes of relative porosityand measured compressive strength

H d h bl f hi hHydrate phase assemblages for high performance low clinker cements

Li t d l i d lDuncan Herfort

Cementir Holding

Limestone and calcined clayg

65

55

60

50

55

ngth

, MPa

+ 20%

40

45

28 d

str

en

calcined mixed clay

35

2 calcined mixed clay

Metakaolin

calcined Na bentonite30

0 0,2 0,4 0,6 0,8 1

clay content (wt. fraction of clay/(clay+limestone), clinker + gypsum constant at 65%)

65

55

60

50

55

ngth

, MPa

+ 26%

40

45

28 d

str

en

calcined mixed clay

35

2 calcined mixed clay

Metakaolin

calcined Na bentonite30

0 0,2 0,4 0,6 0,8 1

clay content (wt. fraction of clay/(clay+limestone), clinker + gypsum constant at 65%)

300

240

260

280

nsta

nt

CEM I at same fineness

- 18 %

200

220

240

ete

at c

on

- 33%

160

180

200

m3

conc

retr

engt

h

120

140

ssio

n kg

/m st

mixed clayMetakaolin

1000 0,2 0,4 0,6 0,8 1

CO

2em

is

clay content (wt. fraction of clay/(clay+limestone), clinker + y ( y ( y )gypsum constant at 65%)

300

240

260

280

nsta

nt

CEM I at same fineness

- 18 %

200

220

240

ete

at c

on

- 33%

Most studies have shown that 40% replacement is about the limit before the

160

180

200

m3

conc

retr

engt

h supply of Ca is exhausted.To go further other hydrate phases need to form

120

140

ssio

n kg

/m st

mixed clayMetakaolin

to form.

1000 0,2 0,4 0,6 0,8 1

CO

2em

is

clay content (wt. fraction of clay/(clay+limestone), clinker + y ( y ( y )gypsum constant at 65%)

silica gelSiO2

20% Silica fume clays

C0 8SHy

pozzolans

0.8 y

C SH

70% GBFS35% basaltic pozzolan25% granitic pozzolan25% calcined clay or PFA

C-S-Hss

C1.7SHx 25% calcined clay or PFA

stratlingite

C3A.CS.H12

C3A.CC.H12

C3A.3CS.H32

CH

gibsite

C3APortland cement

g

CaO Al2O3Ca needed to form AFm, AFt phases

300

240

260

280

nsta

nt

CEM I at same fineness

- 18 %

200

220

240

ete

at c

on

- 33%

Calcined clays normally require more water for the same consistency and

160

180

200

m3

conc

retr

engt

h therefore more cement for the same strength.However this can be overcome by the

120

140

ssio

n kg

/m st

mixed clayMetakaolin

However, this can be overcome by the correct sequence of mixing with water reducers.

1000 0,2 0,4 0,6 0,8 1

CO

2em

is

clay content (wt. fraction of clay/(clay+limestone), clinker +

reducers.

y ( y ( y )gypsum constant at 65%)

0.6% SP w/b = 0.535% replacement

80

100 cement without SP cement + SP early addition (reference) cement + SP late addition

60

80

Pa)

40

ar S

tress

(P

20

She

a

0 50 100 150 200

0

Shear Rate (s-1)

60

50

55

60

35

40

45

Pa)

25

30

ear S

tress

(

10

15

20

cement early addition

She

0 50 100 150 2000

5

y cement+CB early addition cement+CB late addition

Shear Rate (s-1)

NatroliteNa2Al2Si3O10·2H2O

Alkali activated calcined clay and portland cement

STRUCTURAL EVOLUTION ASSESSMENT

Increasing NS (0 16%)

Futurecem –Workshop 7Aalborg – August 26 -2010

40% clinker, MK/(MK+ls) ratio = 0.96, sodium sulfate content = 0, 4, 10, 16%

Constant water/binder ratio of 0.57

EFFECT OF MK/LIMESTONE RATIO ON STRUCTURE

X-RAY DIFFRACTION – 90 DAYS OF CURING – 40% CLINKER

MK/(MK+ls) ratio: a) 0.80 and b) 0.96

Futurecem –Workshop 7Aalborg – August 26 -2010

STRUCTURAL EVOLUTION ASSESSMENT2

Aluminosilicategel

27Al MAS NMR – 40% CLINKER14.1T, R = 13.0 kHz4 3

2

1

180 days

g

90 days

1

2

Third aluminate

AFm phases

28 days

90 days

3

4

AFt phases

Al(IV) in C-S-H

7 days

28 days

7 days

Futurecem –Workshop 7Aalborg – August 26 -2010

NS = 0% NS = 16%

STRUCTURAL EVOLUTION ASSESSMENT2

Aluminosilicategel

27Al MAS NMR – 40% CLINKER14.1T, R = 13.0 kHz4 3

2

1

180 days

g

Sodium sulfate is an effective activator in mixed CSH – zeolitic systems if the right b l b f d f ffi i tl

90 days

1

2

Third aluminate

AFm phases

balance can be found for a sufficiently high pH for activation and the content of Na needed to balance Al in the framework

28 days

90 days

3

4

AFt phases

Al(IV) in C-S-H

Na needed to balance Al in the framework silicates (must be 1:1).

7 days

28 days

7 days

Futurecem –Workshop 7Aalborg – August 26 -2010

NS = 0% NS = 16%

Conclusion

By combining limestone and alumino silicate pozzolana (FA, calcined clay etc.), the levels of clinker replacement for the same concrete performance canreplacement for the same concrete performance can be extended from about 25% to 40%.

F f th l l f l t lk li f ti tiFor further levels of replacement, alkalis for activation and stabilisation of framework silicates are needed.